John H. Greinwald Jr., Margaret A. Kenna, and Blake C. Papsin
THE NORMAL EAR
ANATOMY
The ear is divided into the external, middle, and inner ear compartments (Fig. 369-1). The external ear consists of the auricle and the external auditory canal. The primary function of the auricle is to channel sound energy toward the middle ear conducting apparatus. The lateral opening of the external auditory canal is the external meatus, which is bordered medially by the tympanic membrane. The lateral one third of the external canal is cartilaginous, and the medial two thirds are bony. The canal is lined by skin that possesses cerumen glands and other adnexal structures (hair follicles, sebaceous glands) in its lateral half.
The normal tympanic membrane (Fig. 369-2) seals the opening between the external auditory canal and the middle and inner ear. The portion of the tympanic membrane inferior to the short process of the malleus (pars tensa) is a three-layered structure composed of a medial mucosal epithelium continuous with the middle ear mucosa, a middle fibrous tissue layer, and, finally, a lateral surface of squamous epithelium continuous with the external ear canal skin. The region of the tympanic membrane superior to the short process of the malleus (pars flaccida) does not have a middle fibrous layer, which is clinically significant because it allows the development of retraction pockets and acquired cholesteatomas.
The middle ear compartment is an aerated cavity that houses the three ossicles: malleus, incus, and stapes. The function of the ossicles is to efficiently transmit sound energy to the inner ear. The middle ear is connected to the nasopharynx anterosuperiorly via the eustachian tube. Posterior and superiorly, the middle ear cavity is connected to the mastoid air cell system by means of the mastoid antrum. These connections provide a pathway for extension of middle ear infection into the mastoid. This can cause coalescent mastoiditis.
The inner ear is divided into an auditory portion (the cochlea), a vestibular portion (three semicircular canals, the utricle, and the saccule), and the endolymphatic apparatus (the endolymphatic duct and sac). The cochlea is a coiled structure that houses the machinery responsible for transducing sound energy into neural impulses. The actual transducers are hair cells, which are precisely arranged in the organ of Corti. The organ of Corti, in turn, rests on the basilar membrane, which resonates in response to the incoming acoustic stimuli. The cochlea maintains a very specific fluid balance. The endolymph has a composition similar to intracellular fluid (ie, high potassium and low sodium), whereas the perilymph has a composition similar to that of extracellular fluid (ie, low potassium and high sodium). The establishment of this electrochemical gradient is critical for signal transduction and hearing. Clinical disorders that perturb this fluid homeostasis result in hearing loss and/or balance dysfunction.
The semicircular canals are oriented at approximately 90 degrees to each other, allowing detection of angular head motion in any given plane. Hair cells within the sensory portions of the semicircular canals are deflected in response to head movement in a particular plane of motion. The utricle and saccule represent organs for the detection of linear or gravitational acceleration. Congenital deformities affecting only the vestibular portion of the inner ear are rare but have been reported in association with other ear anomalies such as Goldenhar syndrome. Children with congenital vestibulopathy usually present with a delay in development of motor skills.
The endolymphatic duct and sac are believed to play a role in the maintenance of the specific fluid homeostasis of the inner ear. The vestibular aqueduct serves as the bony channel that transmits the endolymphatic duct and sac. Abnormalities of the endolymphatic sac are found in patients with Pendred syndrome. Enlarged vestibular aqueduct (EVA) is the most common bony abnormality of the inner ear and is present in about 25% of patients with sensorineural hearing loss (SNHL). The presence of an EVA has also been linked to hearing loss following relatively mild head trauma in children.
EMBRYOLOGY
At approximately 6 weeks of gestation, the mesoderm of the first and second branchial arches condense, giving rise to six hillocks of His. These hillocks are responsible for the formation of the auricle, which is mature in shape by 20 weeks. The external auditory canal is initially a solid core of ectoderm that invaginates medially at about 8 weeks. This core then undergoes resorption and canalization to leave a tubelike structure by 28 weeks. The most medial ectoderm remains intact to serve as the surface epithelium of the tympanic membrane. Congenital microtia reflects an abnormal development process and is estimated to occur in up to 1 in 20,000 births. Atresia of the external auditory canal similarly points toward a development problem, typically believed to occur during the end of the first or beginning of the second trimester.
Figure 369-1. Anatomy of the ear: external, middle, and inner components.
The eustachian tube forms from the space between the second arch and the first pharyngeal pouch (pharynx). The middle ear cavity then develops from an outpouching at the lateral end of the eustachian tube primordium. The mastoid air cell system begins with the antrum. The middle ear system is filled with mucoid mesenchyme and secretions until close to the time of birth. The malleus and incus are derived from first and second branchial arch mesoderm and begin ossification as early as 16 weeks of gestation, when they are already of adult size. Auricular malformations such as microtia are of clinical relevance. Because the auricle forms early, it may be associated with concomitant malformation of the middle ear and mastoid. In contrast, a normal auricle with canal atresia suggests a developmental defect occurring around 28 weeks, a time when the ossicles and middle ear are already formed.
Figure 369-2. Normal tympanic membrane anatomy and landmarks. (Source: Knoop KJ, Stack LB, Storrow AB, Thurman RJ. The Atlas of Emergency Medicine. 3rd ed. New York: McGraw-Hill; 2010. Photo contributor: Richard A. Chole, MD, PhD.)
The inner ear develops from a thickening of the surface ectoderm, the otic placode, and forms the primitive otocyst at approximately 4 weeks of gestation. This otocyst forms the membranous labyrinth, including the cochlea, vestibular structures, and endolymphatic apparatus. By 6 weeks, the semicircular canals are well formed, and by 12 weeks, the cochlea completes its two and a half turns. Ossification of the inner ear structures begins at 15 weeks and is typically complete by 23 weeks of gestation. With the exception of the endolymphatic apparatus, the inner ear is approximately adult size by the end of 24 weeks.
PHYSIOLOGY
The length and shape of the external auditory canal imparts a particular optimal resonance frequency that affects an individual’s maximum sensitivity to sound. For most people, the ear demonstrates maximum sensitivity in the range of speech frequencies. The tympanic membrane and ossicles then further refine that sound energy conduction by means of focusing the energy onto the oval window and by employing a lever mechanism that confers a mechanical advantage to the system. Once the sound energy reaches the cochlea, it causes a specific portion of the basilar membrane to vibrate according to the frequency of the sound. This resonance of the basilar membrane then results in deflection of a specific set of hair cells and generation of an action potential. The “tonotopic” or frequency-specific arrangement of the basilar membrane and the cochlear hair cells is mirrored in the central auditory pathway of the brainstem and brain, where specific neurons are activated depending on the frequency of sound detected.
In the vestibular system, deflection of hair cells again forms the basis for signal transduction. Flow of endolymph either toward or away from the vestibule causes either an increase or decrease in firing rate of vestibular sensory cells, depending on which particular semicircular canal is involved.
EVALUATION OF THE AUDITORY AND VESTIBULAR SYSTEMS
HISTORY
Behaviors such as inattentiveness, constant use of an inappropriately loud voice, excessive volume on televisions or radios, or even difficulty in classrooms can all be indicators of hearing loss. The onset and duration of hearing losses should be noted because the workup and management of congenital and acquired hearing losses differ. Associated symptoms such as pain, pressure, or drainage from the ears may also be significant features guiding the differential diagnosis. Symptoms of dizziness in the child are difficult to elicit and evaluate but if suspected they should be evaluated in order to rule out an inner ear vestibular disorder. Occasionally, the child with vestibular pathology presents with a developmental delay in motor skills or ambulation. A thorough history should also include inquiries into possible trauma. Foreign bodies in the ear canal or insertion of small objects into the ear can damage the tympanic membrane or even the ossicular chain, possibly resulting in hearing loss.
Social factors such as daycare attendance and exposure to second-hand smoke have been linked to an increased incidence of otitis media with effusion with hearing loss. A family history of hearing loss, particularly if in first-degree relatives is important when considering genetic causes of hearing loss.
Although universal newborn hearing screening is the standard across the United States, a complete history for the auditory system should explore prenatal and perinatal complications such as preeclampsia, infections including cytomegalovirus and toxoplasmosis, premature delivery, low Apgar scores, hyperbilirubinemia, low birth weight, neonatal intensive care unit admission, and ventilatory support.1 All are associated with an increased risk of hearing loss. At present, most newborn hearing screening programs use the auditory brainstem response (ABR) and/or otoacoustic emissions (OAEs) to evaluate those children at risk. (These are described later in this chapter.)
PHYSICAL EXAMINATION
Evaluation of the auditory system begins with observation of the overall craniofacial appearance. Shape of the auricle, position of the auricle, or any associated skin tags or preauricular pits suggest a possible abnormality of the auditory system. One of the more common causes of hearing loss in children is an accumulation of cerumen. A thorough exam of the ear requires gentle removal of any debris in the external auditory canal. Pulling the auricle posteriorly and superiorly can straighten the ear canal to facilitate examination.
A pneumatic otoscope is used to examine all structures from the external meatus to the tympanic membrane. Careful choice of the largest speculum that can comfortably fit within the child’s ear also facilitates this examination. The normal anterior canal wall of the external auditory canal demonstrates a “bulge” that obscures the anterior one third to one half of the tympanic membrane. To fully view the tympanic membrane, it is necessary to position the tip of the speculum accurately at this juncture and to angle the examiner’s view in an anterior direction.
The skin of the external meatus and external auditory canal should be surveyed for erythema, edema, lesions, or drainage. A reddened and swollen external canal with clear or purulent drainage suggests an external otitis, commonly referred to as “swimmer’s ear,” or secondary infection from middle ear drainage. The tympanic membrane should be evaluated for its overall integrity, color, vascularity, translucency, and mobility. Particularly significant areas to examine include (1) the superior part of the tympanic membrane (pars flaccida), where retraction pockets and acquired cholesteatomas frequently originate; (2) the anterior tympanic membrane, an area medial to which congenital cholesteatomas are noted; and (3) the remaining pars tensa, which is the most readily visualized portion of the tympanic membrane.
The tympanic membrane is normally a pale white or grayish structure. An erythematous tympanic membrane most commonly suggests an inflammatory process involving either the middle ear space or the drum itself. Subtle color changes in the tympanic membrane may suggest underlying vascular abnormalities of the middle ear. A bluish hue to the tympanic membrane can indicate a high jugular bulb protruding into the middle ear space, and a reddish coloration or mass seen in the tympanic membrane might raise the suspicion of an anomalous internal carotid artery in the middle ear. The vascularity of the tympanic membrane itself can also be an indicator of the status of the tympanic membrane and the middle ear space. The normal partial translucency provides some indication of the status of the middle ear structures and space. In the healthy ear, the short process, manubrium, and umbo of the malleus are readily visible (Fig. 369-2). The shadow or outline of the incus and the dense bone of the promontory are also discernible. Middle ear effusions, thickening of the tympanic membrane, or other middle ear pathology such as cholesteatoma may obscure these structures. The integrity of the tympanic membrane should also be assessed. Finally, with a speculum that is large enough to seal off the external auditory canal, a pneumatic otoscope should be used to gently move the tympanic membrane with a puff of air. Decreased mobility of the tympanic membrane is most commonly a result of fluid in the middle ear space and can be one of the most useful clinical findings for diagnosing otitis media with effusion.2
TESTS OF FUNCTION
Audiometry provides a quantitative measure of hearing and functionally assesses the entire auditory system. A trained audiologist uses one or more of a battery of testing techniques available, depending on the child’s age and development. All children with suspected or confirmed ear pathology, suspected congenital hearing loss, or a delay in the development of communication skills should undergo formal audiologic testing as early as possible. Physical exam screening tests such as making noise and looking for a head turn in a young child are inadequate in the setting of parental concern for hearing loss or delayed speech. No child is too young to have a hearing test.
Conventional Audiometry
For the cooperative child, typically 5 years of age or older, an audiometer can be used to measure ear-specific sensitivity to individual pure tones ranging from low tones at 256 Hertz to high tones at 8000 Hertz (Fig. 369-3). In most instances, pure tones can be heard at less than 20 to 25 decibels sound pressure level. In addition to pure tone thresholds, speech audiometry can be performed in these children. The speech reception threshold (SRT) refers to the intensity required to detect speech, as opposed to simple pure tones. The SRT is usually similar in value to the pure tone average, which is the average of the pure tone thresholds at 500, 1000, and 2000 Hertz. The speech recognition score refers to the child’s ability to recognize and repeat a standard set of phonetically balanced words presented at an intensity that can be heard comfortably, based on pure tone thresholds and SRT. These standard tests are invaluable in documenting a child’s baseline hearing level, determining whether the hearing level will affect the child’s development, and providing an objective means of assessing a child’s response to treatment for ear disease. For children who are too young to cooperate with these auditory techniques, behavioral testing represents a relatively inexpensive and noninvasive means of assessing a child’s hearing levels. Between the ages of 18 months and 5 years, children can be motivated to participate in activities that reflect whether a test stimulus was heard. Visual reinforcement audiometry involves testing the child in a sound-treated room with loudspeakers positioned at each side of the child. To maintain the child’s interest or to condition the child to respond when auditory stimuli are heard, a toy is typically activated near the speaker that elicited the response. By combining behavioral observation and visual reinforcement audiometry, the audiologist can usually obtain a reasonable impression of a child’s auditory capabilities.
Figure 369-3. Conventional audiogram with left-sided hearing loss. O, right; X, left; SRT, speech reception threshold.
Evoked Auditory Brainstem Response and Otoacoustic Emission Testing
Auditory brainstem response (ABR) uses scalp electrodes placed on the skin to detect neural impulses following the delivery of various auditory stimuli to the ear. Computer-based averaging of neural activity allows for the calculation of “latencies” between distinct wave peaks. Evaluation of waveform morphology, the stimulus intensities required to elicit responses and the latencies of the wave peaks provide a qualitative assessment of the child’s auditory system.
Otoacoustic emission (OAE) testing is used to evaluate the peripheral auditory system. This method uses an extremely sensitive microphone that is placed in the external ear canal close to the tympanic membrane. Faint sounds generated by the outer hair cells of the cochlea are recorded. These sounds are generated either spontaneously or in response to auditory stimuli. The stimuli are referred to as transient evoked OAEs or distortion product OAEs. Because OAEs are believed to be generated by the outer hair cells of the cochlea, they may help identify or rule out the cochlear hair cells as the site of pathology in patients with sensorineural hearing loss (SNHL).
Immittance Audiometry/Tympanometry
Acoustic immittance is a generic term used to refer to either the opposition (impedance) or ease of entry (admittance) of acoustic energy into the middle ear transmission system. By means of a specialized earplug that seals off the external auditory canal, it is possible to measure the acoustic immittance of the ear. Contained within the earplug are a miniature speaker, air pump, and microphone. The ear normally absorbs sound energy through the tympanic membrane and middle ear structures. Impedance provides an indirect measure of this sound absorption function by measuring the reflected sound energy. The speaker delivers sound into the external auditory canal while the pressure is varied by the air pump. The microphone then detects the sound reflected back from the ear.
Several patterns of tympanograms are routinely encountered and reflect varying states of middle ear function (Fig. 369-4). The type A tympanogram is normal, with the curve peaking at approximately 0 cm H2O. The type B tympanogram is typically flat or shows only a very shallow peak. Such tympanograms are seen in cases of otitis media with effusion or ossicular fixation. A tympanic membrane perforation can also result in a flat tympanogram but is usually associated with an abnormally large canal volume; this volume is measured routinely during tympanometry. The type C tympanogram most commonly reflects a retracted tympanic membrane and shows a curve that peaks at pressures less than –150 cm H2O. Less reliably, tympanosclerosis and otosclerosis (caused by fixation of the stapes footplate) may be reflected in the type AS tympanogram. Last, the type AD tympanogram shows an abnormally high peak in an otherwise normal curve and is usually associated with ossicular discontinuity or an unusually mobile, atelectatic or atrophic tympanic membrane.
Vestibular (Balance) Testing
Several advances in the diagnosis of vestibular dysfunction have improved the diagnostic evaluation of children with dizziness. Electronystagmography (ENG) is extremely useful and is performed by applying electrodes around the eyes that detect the corneoretinal potential, which assesses eye movements. The function of the inner ear vestibular apparatus is evaluated by stimulating the inner ear with warm and cold water or air irrigation, which normally produces a characteristic nystagmus based on the vestibuloocular reflex. Cold irrigations in one ear normally cause a nystagmus in the opposite direction, whereas warm irrigations produce a nystagmus toward the ipsilateral ear. Quantification of the eye movements allows an objective measure of the vestibular function of each inner ear and can provide data for discriminating between peripheral and central vestibular dysfunction. More recent improvements in ENG testing include the use of video-infrared ENG systems, referred to as VNG. These systems involve video cameras mounted inside a pair of goggles that “lock onto” the retina by means of a computer-controlled mechanism.
Figure 369-4. Illustration of various types of tympanograms. A, normal tympanogram, maximal peak (compliance) seen at 0 mm H2O; AD, deep (hypermobile tympanic membrane as seen with atelectasis or ossicular discontinuity); AS, shallow (stiff tympanic membrane as seen with tympanosclerosis or otosclerosis); B, nonmobile tympanic membrane, normal canal volume (a middle ear effusion); type B high canal volume, nonmobile tympanic membrane has no pressure differential across it (tympanostomy tube or perforation); C1, mild negative middle ear pressure (eustachian tube dysfunction); C2, negative middle ear pressure below –200 mm H2O (usually a middle ear effusion).
Computerized platform posturography also represents a significant advance in vestibular testing. By using a platform that the test subject stands on, the child’s center of gravity can be recorded both statistically as well as in response to movement of the platform. Data from such tests provide insight into the child’s overall balance function, be it centrally or peripherally controlled. Certain patterns of body movements or failures to compensate for platform movement can indicate cerebellar dysfunction.
In addition, rotary chair testing allows for the audiologist to provide data on the function of the vestibular system, even when there is minimal patient cooperation. The child sits with or without the parent in a slowly rotating chair while eye measurements are recorded.
RADIOGRAPHIC EVALUATION
Computed tomography (CT) and magnetic resonance imaging (MRI) are currently the standard of care in evaluating children with otologic disease.3 Optimal axial and coronal CT images of the ear using 1-millimeter cuts through the temporal bone identify minute pathology that can be significant in the middle ear, mastoid, and inner ear regions. Bone window images typically provide the greatest information regarding the external, middle, and inner ear regions. In the external and middle ear, CT can demonstrate opacification of the air spaces, erosion of bony structures or ossicles, atretic plates of the external canal, and other middle ear congenital abnormalities. In the inner ear, CT can clearly show the auditory and vestibular structures of the inner ear labyrinth, as well as the internal auditory canal that transmits the facial, cochlear, and vestibular nerves. CT also readily demonstrates aplasias and other malformations of the inner ear. Notably, an enlarged vestibular aqueduct (EVA) is best demonstrated by CT.
Gadolinium-enhanced MRI provides an excellent means for assessing the soft tissue structures of the ear. One-millimeter cuts through the temporal bone accurately visualize critical neural structures, including the facial, cochlear, and vestibular nerves. With the use of gadolinium, these structures can also be evaluated for signs of inflammation or neo-plastic involvement. Enlargements of the endolymphatic sac are best seen on MRI studies.4
DISORDERS OF THE EAR
CONGENITAL AND ACQUIRED HEARING LOSS
EPIDEMIOLOGY
Approximately 1 in 1500 children has a severe to profound hearing loss at birth or in early childhood. This relatively high incidence, the high likelihood of significant negative developmental impact in children with hearing loss, and the significant technological capabilities to habilitate children with hearing loss have lead to most developed countries instituting universal newborn hearing screening protocols. These protocols are designed to identify all children with hearing loss at an early age so that intervention can be provided during the critical early periods of speech and language development.5,6 The most common causes of acquired hearing loss in children is a conductive hearing loss that results from abnormalities of the middle ear (especially otitis media and ossicular abnormalities), whereas congenital hearing loss is often a result of sensorineural deficits.
PATHOPHYSIOLOGY AND GENETICS
eTable 369.1 lists common causes of congenital hearing loss. Various series estimate that upward of 50% of these cases are genetic in origin (eFig. 369.1 ). Of these patients, approximately 70% have isolated hearing loss as the only phenotypic manifestation (ie, nonsyndromic hereditary hearing impairment). The remaining have hearing loss in conjunction with other abnormalities (ie, syndromic hearing impairment associated with Pendred, Usher, Wardenburg, Brachio-oto-renal, and other syndromes). In patients with nonsyndromic hereditary hearing impairment, the vast majority (∼80%) display an autosomal-recessive mode of transmission. Another 15% are estimated to have an autosomal-dominant mode of inheritance, with the remainder being X linked or mitochondrial in nature. The known genetic disorders associated with hearing loss are found in Table 369-1.
Studies of large kindreds with hearing loss have identified multiple genetic loci associated with nonsyndromic hearing impairment. To date, 21 autosomal-dominant (DFNA) genes, 22 autosomal-recessive (DFNB) genes, and 1 X-linked (DFN) gene have been identified. An illustrative example of the clinical relevance of these genetic discoveries can be seen with the gene GJB2 (gap junction ?-2 protein), which is also known as connexin 26 (CX 26).7 Studies have identified more than 100 different mutations in GJB2 as a cause for hearing loss. The most common mutation is 35delG, which accounts for about one third of all mutations. Routine lab testing is now used to identify CX 26 mutations, which subsequently helps predict future hearing deterioration and success with cochlear implantation. Mutations in genes such as SLC26A4, 12SrRNA, MYO7A, OTOF, and CDH23 are also believed to account for a significant proportion of hearing loss in the general population.
A history of maternal “TORCH” infections (Toxoplasmosis, Other agents such as Coxsackie virus and Listeria, Rubella, Cytomegalovirus [CMV], Herpes simplex) during pregnancy can indicate a likely etiology for congenital hearing loss in a child. Rubella, for example, is particularly associated with cochleosaccular dysplasia and congenital deafness. Prenatal CMV infection may account for up to 40% of all children with sensorineural hearing loss (SNHL) (see Chapter 310). SNHL is seen in 5% to 10% of children with asymptomatic CMV infection and in more than 50% of children with symptomatic CMV infection. A history of maternal drug use during pregnancy may also be important. For example, isotretinoin causes congenital hearing loss with associated malformations of the cochlea. Substances such as alcohol, cocaine, and other “recreational” drugs may also cause congenital hearing loss. Perinatal factors such as prematurity, low birth weight, low Apgar scores, and the need for neonatal intensive care unit (NICU) admission have all been correlated with SNHL. Complicated delivery with infant anoxia or severe dystocia requiring forceps delivery may provide insight into the cause of congenital hearing loss. Traumatic deliveries can cause mastoid and middle ear damage that result in conductive hearing loss and/or SNHL.
Table 369-1. Common Genes Associated with Nonsyndromic Sensorineural Hearing Loss
During the very early postnatal period, routine screening of infants for problems such as hypothyroidism or phenylketonuria is now commonplace. Therefore, the likelihood of missing these possible etiologies of hearing loss is minimal. Other risk factors for hearing loss at this time include hyperbilirubinemia (typically > 17.0 mg/dL), metabolic defects, and a wide range of hereditary congenital processes that manifest with hearing loss.
DIAGNOSIS
The physical examination of the ear in infants should focus on identifying features that might suggest associated inner ear anomalies. For example, stenosis or atresia of the external auditory canal associated with preauricular pits or skin tags can suggest branchio-oto-renal syndrome, a fairly common congenital deafness syndrome associated with malformation of the cochlea. Early audiometric testing is essential in suspected congenital hearing loss. As discussed previously, accurate audiometric results can be obtained on any age child through behavioral testing and/or auditory brainstem response (ABR) and otoacoustic emission (OAE) testing. Figure 369-5 is an algorithm for the diagnostic assessment and treatment of patients with either conductive or sensorineural hearing loss.
MANAGEMENT OF CHILDREN WITH CONFIRMED HEARING LOSS
The management options for children with confirmed hearing loss have changed dramatically over the past decade. Figure 369-5 provides an algorithm for the evaluation and management of children with suspected hearing loss, and eFigure 369.2 provides an approach to the management of children with hearing loss detected at infant screening. Once hearing loss is confirmed using an age-appropriate audiologic modality described earlier in this chapter (behavioral audiometry, auditory brainstem response [ABR], otoacoustic emissions [OAEs]), evaluation next is focused upon determining if the hearing loss is due to a sensorineural hearing loss (SNHL) or conductive hearing loss (CHL).
Figure 369-5. Algorithm for the evaluation of suspected hearing loss. BAHA, bone anchored hearing aid; HL, hearing loss.
Identifying a child SNHL mandates referral to an otolaryngologist and consideration of vaccination against Streptococcus pneumoniae. Vaccination is recommended in this population because children with congenital SNHL have an increased incidence of underlying cochleovestibular anomaly and a small increased risk of otogenic meningitis. Identificacation of those children in whom there is progression of the hearing loss or severe to profound SNHL is a priority because children in these groups are more likely to require surgical intervention (cochlear implantation). In children with less severe hearing loss, follow-up by an audiologist is crucial to monitor for progression of loss, and to monitor the efficacy of hearing aids. Continued follow-up by the audiologist and otolaryngologist should continue until children are able to reliably report hearing changes and are able to engage in behavioral testing for each ear individually. All children with sensorineural hearing loss should also undergo opthamalologic evaluation prior to since over 14% to 20% will have abnormalities. These are particularly common in children with mutations in GJB2.8An electrocardiogram should also be performed to identify those children with Jervell and Lange-Neilsen syndrome, which is a rare disorder consisting of profound SNHL and syncopal episodes resulting from cardia conduction defects (associated with disorders of KVLQT1 and KCNE1 genes).
The timing of imaging and genetic evaluation varies among individual practitioners. If there is progression of hearing loss or a severe to profound hearing loss present, imaging of the temporal bone (CT and MRI are complimentary) and genetic evaluation should be performed to allow diagnosis of the underlying cause of hearing loss (35% of deaf children have anomalous cochleovestibular anatomy) or to prepare for possible surgical intervention. Routine imaging of infants with SNHL incurs the risk of sedation and radiating the developing central nervous system for little immediate benefits except in the profoundly deaf child being assessed for cochlear implantation.
Figure 369-5 and eFigure 396.3 show the far simpler algorithm for managing conductive hearing loss (CHL). CHL occurs when sound transmission is physically impeded in either the external and/or the middle ear. Evaluation includes physical examination to assure the external ear canal is patent. Otoscopy may reveal cholesteatoma, otosclerosis, or an abnormality of the tympanic membrane, malleus or incus. CT is useful for diagnosis of abnormalities of the middle ear structure.
Rehabilitative options include training that emphasizes audition enhanced by technologic approaches to the development of spoken language (eg, auditory-verbal or auditory-aural therapy), the use of manual forms of communication (eg, sign language), or both (eg, total communication, cued speech). All approaches are directed by specialized professionals such as auditory verbal therapists or special education teachers, but they require a significant commitment by parents and caregivers. The decision of parents and caregivers to choose oral or manual communication mode for their child is based on a number of factors, including the severity of the loss, attitudes about deafness, professional recommendations, and costs.
If oralism is desired, hearing aids are prescribed immediately after the diagnosis of hearing loss is made, even in small infants.9 When bilateral conductive losses are present (ie, aural atresia/microtia), a bone conducting hearing aid is prescribed. There is some controversy about the need for rehabilitation in unilateral CHL and SNHL because the outcome depends upon a number of other factors. Therefore in cases of unilateral hearing loss, with documented normality in one ear, the decision to utilize a hearing aid can be deferred.
Most children with hearing loss can be managed fully with hearing aids that come in an increasingly acceptable array of designs. FM systems and telecoils allow the children to attend to important stimuli (ie, teachers, phone conversations, public performances) and diminish background noise in learning environments. Studies have shown that even children with normal hearing demonstrate academic improvement when placed in classrooms equipped with FM systems broadcasting so as to diminish background noise.
The surgical rehabilitation of children with SNHL using cochlear implants has totally revolutionized our management during the past decade.10 The cochlear implant is a device that digitizes acoustic information and converts it to an electrical signal that is then sent into the cochlea, where stimulation of the auditory system occurs. The auditory system is tonotopic along its entire course through the cochlea, auditory nerve, and brainstem and even up to the cortex, thus making stimulation of the surviving spiral ganglion and auditory nerve fibers at discrete locations within the deaf cochlea sufficient to allow auditory perception of specific frequencies and patterns of sound. Remarkably, the human can quickly and reliably make use of this information and codify speech and language because the child’s auditory system is tremendously plastic, and there exist sensitive periods within which, development can maximally occur to increase the chance that the child will obtain oralism (spoken language without non-auditory cues). Capitalizing on this plasticity has led to routine early implantation, with surgery commonly being performed on children as young as 8 months of age. The linguistic performance achieved by these children born profoundly deaf and implanted early are astounding with well more than 80% attending first grade in a mainstream classroom setting. Bilateral cochlear implantation provides possibly an even better way of allowing optimal auditory development, in this case for binaural auditory fusion of the auditory environment in the central auditory system.11 Early study results show improved speech in noise and some improvement in the ability to localize sounds in space after bilateral implantation.
Management options for CHL have also undergone significant advances recently with the introduction of bone anchored hearing aids (BAHA).12 Initially indicated for bilateral congenital CHL (aural atresia/microtia [eg, Treacher-Collins syndrome], syndromic CHL without atresia [eg, branchial-oto-renal syndrome]), BAHA is now more liberally applied based on its success and is used in the rehabilitation of CHL due to bilateral cholesteatoma, chronic suppurative otitis media, and even in some cases of unilateral SNHL to remove the head shadow effect. Application in some children with nonre-solving (permanent) otitis media with effusion (eg, Down syndrome) has been shown to be tremendously successful. These implants consist of a titanium fixture that is implanted into the skull posterosuperior to the external auditory canal (or where it will be after microtia repair) and allowed to osseointegrate. In children, the interval between this first surgical stage and the second (the interstage interval) is determined by the thickness of the cortical bone (the thinner the bone, the longer the interval). At the second surgical stage, the skin is thinned, elevated, and then replaced, but now with a steel abutment penetrating through it; on this abutment, after healing of the skin has occurred, the BAHA is attached. The BAHA effectively eliminates CHL and delivers sound at the level of the sensorineural thresholds (which are almost always near-normal in congenital CHL in children). There are new middle ear implants that will be available in the next decade; however, they are not yet durable enough to routinely implant them into children, and BAHA remains the standard prosthetic surgical option for these children.
VERTIGO
Vertigo often presents with a complaint of “dizziness.” The approach to diagnosis is outlined in Figure 369-6.13 Differentiating the variety of experiences that may be termed “dizziness” by a child or parent is challenging. Even adults have difficulty describing the experience of a vertiginous attack accurately. In a child, vertigo may not be described at all but rather may be reflected in unusual behaviors. Sudden falls, grasping for support, or even an unwillingness to move can all represent signs of vertigo. True vertigo implies an overwhelming sensation of the world spinning, often accompanied with nausea and vomiting. “Dizziness” that is sometimes seen with postural hypotension or cardiac arrhythmias is often not related to vertigo. Similarly, a history of visual disturbance rarely supports a diagnosis of vertigo. The history should include questions regarding accompanying ear symptoms and other systemic symptoms. A review of systems should address possible head trauma or barotrauma that may result in a perilymphatic fistula. The family history should focus on any family members with migraine or seizure disorders because either (especially migraine) can present with vertigo as a primary symptom in children.
Figure 369-6. Algorithm for the evaluation of vertigo. PLF, perilymphatic fistula.
Physical examination findings of pigmentary lesions or neurofibromas, signs of trauma, abnormal facies, or congenital abnormalities of the external ear or eyes are meaningful. The otologic exam must rule out middle ear disease as a possible cause for the vertigo. Acute otitis media (AOM), otitis media with effusion (OME), or chronic suppurative otitis media (CSOM) can cause vertigo or, more frequently, a subtle compromise of balance. Cranial nerve deficits suggest possible brainstem lesions or tumor as an etiology. Abnormal visual tracking, convergence, or saccades as well as spontaneous nystagmus are important findings in a child with vertigo. Simple tests of balance and coordination are extremely informative in children. Tasks such as hopping on one foot, performing a tandem gait, standing on a foam cushion, or simply standing from a seated position on the floor may uncover neurologic deficits. Repeating the tasks with eyes closed helps identify those children who have compensated for vestibular deficits by relying on visual cues.
Causes of vertigo are most easily considered as being of either a central or a peripheral etiology (Table 369-2). Congenital anomalies, central nervous system infections or neoplasms, trauma, and vascular anomalies may present with vertigo. Peripheral disorders involve the labyrinth or eighth nerve. These can either result from congenital abnormalities or may be acquired. The most common peripheral disorders causing vertigo in a child include a posttraumatic perilymphatic fistula (a leakage of inner ear fluid into the middle ear, usually from the oval or round windows), ototoxic medications, cholesteatoma, otitis media, benign positional vertigo, and benign paroxysmal vertigo of childhood. True Ménière’s disease in children is very rare.14 Although the underlying etiology should be addressed when possible, temporary symptomatic improvement may be obtained with vestibular suppressants such as diazepam or meclizine. This also applies in cases in which the underlying etiology is unclear. Systemic steroids may be of benefit with central neoplasms and demyelinating disorders, viral labyrinthitis, vestibular neuronitis, and syphilitic inner ear disease. Based on the history and physical examination, appropriate hematologic and serologic tests, audiovestibular testing, imaging studies, or electroencephalographic (EEG) studies can be performed to help pinpoint a likely diagnosis. All patients with vertigo should undergo routine audiologic testing. Because of the anatomic, physiologic, and pathologic associations of hearing loss with vestibulopathy, audiologic studies often provide either diagnostic or supportive data for a diagnosis. Similarly, electro-nystagmography (ENG) is a critical diagnostic tool for evaluating a child’s vestibular function. Other tests that are helpful are moving platform posturography (MVP), to attempt to quantify balance and the vestibular evoked myogenic potential test (VEMP); this test assesses the vestibulospinal pathway by means of acoustic or galvanic stimuli. The functional status of the vestibular system as measured by ENG can help distinguish central from peripheral etiologies, identify asymmetries in responses of a patient’s inner ears, and define the percentage reduction in vestibular response for a pathologic inner ear. Potentially useful laboratory tests include a spot glucose to rule out diabetes or hypoglycemia, electrolyte studies, thyroid function tests, and serology for HIV-1, Borrelia burgdorferi (Lyme disease pathogen), Mycobacterium tuberculosis, and Treponema pallidum (FTA-ABS).
Table 369-2. Causes of Vertigo
|
Central Vertigo Etiologies |
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Congenital |
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Chiari malformations |
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Infections |
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Meningitis |
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Encephalitis |
|
Brain abscess |
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Neoplasm |
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Tumors of the cerebellum |
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Tumors of the cerebellopontine angle |
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Tumors of the brainstem |
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Trauma |
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Vascular |
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Arteriovenous malformations |
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Basilar artery migraine |
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Migraine equivalent |
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Demyelinating disorders |
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Cerebellar ataxias |
|
Seizure disorders |
|
Peripheral Vertigo Etiologies |
|
Congenital |
|
Labyrinthine dysplasia/aplasia |
|
Stenosis of the internal auditory canal |
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Congenital cholesteatoma |
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Genetic |
|
Waardenburg syndrome |
|
Usher syndrome |
|
Pendred syndrome |
|
Alport syndrome |
|
Down syndrome |
|
Infection |
|
Otitis media with effusion |
|
Suppurative otitis media |
|
Cholesteatoma |
|
Bacterial labyrinthitis |
|
Viral labyrinthitis |
|
Syphilitic inner ear disease |
|
Lyme disease |
|
Vestibular neuronitis |
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Trauma |
|
Perilymphatic fistula |
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Labyrinthine concussion |
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Iatrogenic/surgical |
|
Otoxins |
|
Aminoglycosides |
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Chemotherapeutic drugs |
|
Radiation |
|
Benign positional vertigo |
|
Benign paroxysmal vertigo of childhood |
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Benign paroxysmal torticollis |
LABYRINTHITIS
Labyrinthitis refers to an inflammatory process involving the inner ear (membranous labyrinth). Accordingly, the manifestations of labyrinthitis are typically vertigo, hearing loss, and tinnitus. The severity of symptoms correlates with the intensity and etiology of the inflammatory process in the inner ear. In cases of serous labyrinthitis, symptoms are typically mild, with the child complaining of “dizziness” without any substantial hearing loss. Most cases of serous labyrinthitis are associated with concomitant acute or chronic otitis media.
Management of children with serous labyrinthitis is symptomatic and supportive, with treatment of the middle ear disease if present. In contrast, viral labyrinthitis is often associated with a preceding systemic viral illness or upper respiratory tract infection. Patients often report a sudden onset of vertigo or progressive dizziness. Sensorineural hearing loss (SNHL) is rarely a feature of viral inner ear infection in children. The use of corticosteroids may be beneficial. Usually, symptoms abate over 1 to 2 weeks.
Bacterial labyrinthitis is usually a consequence of meningitis and presents as a much more acute process than serous labyrinthitis, with severe vertigo and acute hearing loss. Inoculation of the inner ear fluids by pathogenic bacteria through preformed pathways and/or the cerebrospinal fluid is the most likely mechanisms of infection. Loss of cochlear and vestibular hair cells, secondary scarring, and ossification of the labyrinth often follow bacterial labyrinthitis, which explains why spontaneous recovery of hearing is unlikely. If bacterial labyrinthitis is suspected, parenteral antimicrobial therapy is indicated, along with antiemetics. When this condition is seen in conjunction with other acute infectious processes such as meningitis, treatment is directed at the primary pathologies.
NEOPLASMS OF THE EAR
Neoplasms of the ear are rare in childhood, with benign lesions being far more common than malignancies. Osteomas can present as smooth bumps or masses in the external auditory canal (Fig. 369-7). These are most commonly noted in swimmers and result from cold-water exposure. Exostoses are also benign bony outgrowths in the external canal and require intervention only if they occlude the canal, causing hearing loss or other problems. Although middle ear masses are unusual in the pediatric population, anatomic variants sometimes masquerade as masses. For example, aberrant internal carotid arteries sometimes present as a reddish pulsatile mass through the tympanic membrane on otoscopy. Similarly, a bluish mass seen in the middle ear space by otoscopy may represent a highriding jugular bulb. Such lesions can cause middle ear symptoms, including hearing loss, otalgia, and otorrhea. Any suspected middle ear mass should be evaluated by imaging studies. Eosinophilic granuloma has been reported to manifest in the temporal bone, and other lesions such as histiocytosis, rhabdomyosarcomas, and lymphomas may also present atypically as ear disease. Leukemic or lymphomatous involvement of the petrous apex marrow spaces has also been reported as a site of neoplastic disease in children. Ear-specific sequelae of neoplasms of the ear include facial paralysis, refractory otalgia, and otorrhea.
Inner ear tumors seen in the pediatric population most commonly involve the seventh and eighth cranial nerve complexes. Facial nerve neuromas or hemangiomas of the geniculate ganglion of the facial nerve represent temporal bone neoplasms that would likely present as facial nerve dysfunction. Pediatric patients with neurofibromatosis type II often have dizziness or hearing loss. These tumors often present bilaterally. Early identification of this disease and surgical intervention may allow preservation of hearing and facial nerve function in these patients.
Figure 369-7. Multiple osteomas almost occlude the external auditory canal. The tympanic membrane can be seen in the center, past the osteomas. (Source: Knoop KJ, Stack LB, Storrow AB, Thurman RJ. The Atlas of Emergency Medicine. 3rd ed. New York: McGraw-Hill; 2010. Photo contributor: C. Bruce MacDonald, MD.)
OTOTOXICITY
Many commonly used over-the-counter and prescription medications can cause damage to the inner ear. The manifestations of ototoxicity can include hearing loss, tinnitus, and vestibulopathy, with different drugs causing one or more of these symptoms depending on the pharmacologic properties of the particular drug. For many drugs, ototoxicity is a well-known risk, and the benefits of treatment must be weighed against the risks of their use to the inner ear. A partial list of drugs that have ototoxic potential is shown in Table 369-3.
Several groups in the pediatric population require increased vigilance for signs of ototoxicity. The high neonatal incidence of serious gram-negative infections such as sepsis, meningitis, and pneumonias requires the frequent use of potentially ototoxic medications. In part, this explains the high risk of ototoxicity in children with a history of prematurity and neonatal intensive care unit admission. It has been reported that some patients who have undergone renal or other organ transplants also show a higher incidence of hearing and balance disorders; however, it is unclear as to whether inner ear problems result from the frequent need for ototoxic medications or dialysis in these patients. Children with cystic fibrosis often require aminoglyco-sides for exacerbations of their pulmonary disease. Finally, children receiving chemotherapy are also at increased risk for inner ear damage from chemotherapeutic agents. Cisplatin, for example, has a well-documented effect on cochlear hair cells and is most commonly associated with a high-frequency hearing loss.
Table 369-3. Drugs with Ototoxic Potential
Drugs such as aspirin and other salicylates demonstrate reversible ototoxicity if stopped in a timely manner after onset of inner ear symptoms. Furosemide alone has been reported to cause sensorineural hearing loss (SNHL), but it has also been shown to potentiate the ototoxic effects of other drugs such as aminoglycosides. Occasionally, the macrolides (erythromycin, azithromycin, clarithromycin) have been reported to be associated with hearing loss; this is usually reversible. Complaints of subjective hearing loss, tinnitus, or disequilibrium may be the earliest signs of ototoxicity. Patients at high risk should undergo routine audiologic testing before, during, and after treatment to measure and document any hearing changes. Similarly, serial electronystagmography (ENG) testing may be useful in cases of vestibulotoxicity.
Many eardrops contain potentially ototoxic components, whether the active ingredients, solutes or preservatives. However, documented cases of permanent SNHL or vestibulopathy resulting from ototoxic medications are rare. Currently, the mainstay of topical otic therapy uses fluoroquinolone eardrops (Floxin and Ciprodex). These are not ototoxic and may be used safely even in the middle ear via a tympanostomy tube or tympanic membrane perforation.
OTITIS MEDIA
Acute otitis media (AOM), otitis media with effusion, and complications of otitis media including chronic suppurative otitis media and mastoiditis are discussed in Chapter 243.
CHOLESTEATOMA
A cholesteatoma is an expanding epithelial-lined sac containing squamous debris, often infected with purulent discharge. Cholesteatomas may be congenital or acquired. They are uncommon and are characterized by a pearly-white keratin mass seen in the middle ear space behind an intact tympanic membrane (Fig. 369-8). The most commonly affected areas for acquired cholesteatomas are the attic region, superior to the short process of the malleus, and the posterior-superior quadrant of the tympanic membrane in the region of the incudostapedial joint. Congenital cholesteatomas are most commonly found in the anterior-superior middle ear space.
ETIOLOGY
The most likely congenital etiology is the embryologic retention of an epithelial cell rest in the middle ear space. Acquired cholesteatomas may occur as the result of perforation or severe tympanic membrane retraction. Rarely, they can occur at the site of a tympanostomy tube insertion.
Chronic negative middle ear pressure may cause a segment of weakened tympanic membrane to retract either in the attic region or in the posterior-superior quadrant. These retractions can cause the inhibition of the natural epithelial migration of desquamated squamous debris. Debris may become wet and infected, producing foul-smelling otorrhea and an expansile mass lesion of squamous debris. The expansion and destruction caused by cholesteatomas may be related to inflammatory mediators secreted by the cholesteatoma itself. Especially in children, who may not complain of the hearing loss often associated with cholesteatoma, these lesions may grow quite large before becoming symptomatic.
Figure 369-8. A cholesteatoma is seen in this ear. Primary acquired cholesteatomas are thought to arise from gradual invagination of the pars flaccida, usually secondary to trauma. Note the yellow epithelial debris from the cholesteatoma in the area of the pars flaccida (arrow). Often there is an effusion and debris, which can distort the anatomy on otoscopy. (Source: Knoop KJ, Stack LB, Storrow AB, Thurman RJ. The Atlas of Emergency Medicine. 3rd ed. New York: McGraw-Hill; 2010. Photo contributor: C. Bruce MacDonald, MD.)
DIAGNOSIS
In a patient with a history of chronic otorrhea, pneumatic otoscopy can help differentiate whether the affected portion of the tympanic membrane is a perforation or a retraction pocket. It may also be possible to observe squamous debris or granulation tissue within a perforation or a retraction pocket. This is suggestive of cholesteatoma. Squamous epithelium desquamating from a cholesteatoma has an appearance resembling cheese. This diagnosis is best made with otomicroscopy using an operating microscope and suction debridement. If a cholesteatoma is suspected, CT scanning of the temporal bone may provide information on the size of the mass and whether surrounding landmarks are involved.
TREATMENT
The treatment of a cholesteatoma involves surgical removal of squamous epithelium in the middle ear and mastoid. Although several different surgical approaches are used to achieve this, almost all of these approaches involve a mastoidectomy. Surgical removal of cholesteatoma is performed initially. This is followed by second procedure allowing confirmation of squamous epithelial removal and subsequent reconstruction of the ossicles. This second stage of treatment is performed approximately 6 to 12 months after the initial procedure.
COMPLICATIONS
A cholesteatoma may cause sensorineural hearing loss (SNHL) or a conductive hearing loss through ossicular erosion. Disequilibrium may occur if a cholesteatoma has invaded the labyrinth. Cholesteatomas have the potential for central nervous system complications. In addition, the potential complications of acute otitis media (AOM) may occur, particularly facial nerve palsy, meningitis, intracranial abscess formation, and sigmoid sinus thrombosis.
TYMPANIC MEMBRANE PERFORATION
ETIOLOGY
Permanent perforations of the tympanic membrane may occur following extrusion of a tympanostomy tube, following acute otitis media (AOM) with tympanic membrane perforation or from direct or indirect trauma to the tympanic membrane. A conductive hearing loss may be the only symptom of a perforation, although recurrent episodes of otorrhea may also occur.
DIAGNOSIS
A small perforation may be asymptomatic or may be associated with a significant conductive hearing loss. Small perforations aerate the middle ear in some patients with chronic eustachian tube dysfunction, in much the same way as a tympanostomy tube. Large perforations are virtually always associated with a conductive hearing loss. Perforation of the tympanic membrane warrants audiologic assessment to estimate the degree of conductive hearing loss. Tympanometry can confirm the presence of a perforation.
TREATMENT
In the presence of otorrhea, treatment with topical antimicrobial eardrops is appropriate. The new generation of quinolone eardrops is particularly effective and nonototoxic. Obtaining a sample for culture and sensitivity is appropriate for persistent otorrhea. Definitive treatment of a tympanic membrane perforation requires surgical repair. In younger children, it is reasonable to delay this repair if ongoing eustachian tube dysfunction is suspected.
COMPLICATIONS
Perforations of the tympanic membrane are usually associated with conductive hearing loss. This hearing loss is exacerbated if the perforation overlies the round window membrane. In the presence of chronic membrane retraction, ossicular discontinuity may also contribute to hearing loss. Rarely, sensorineural hearing loss (SNHL) may occur if there has been long-term chronic suppurative otitis media (CSOM) or external trauma as the cause of the perforation.
OTITIS EXTERNA
Otitis externa (OE) is an inflammatory condition of the external ear, often related to environmental conditions in the outer ear. The healthy external ear is a self-cleaning environment. Cerumen is a protective antibacterial and waterproofing agent produced by the cerumen glands of the outer third of the external ear canal. Normally, cerumen slowly migrates laterally and spontaneously extrudes. The medial two thirds of the external ear canal is bony, with a thin layer of skin that has no cerumen glands. Failure of the cerumen to extrude spontaneously may be due to a number of factors, including (1) hearing aid usage in which the ear mold blocks extrusion, (2) cotton-tip applicator usage where the patient pushes the cerumen medially, or (3) anatomic abnormalities of the ear canal with narrowing and subsequent trapping of the cerumen. The actual volume and consistency of cerumen also affects migration. Pain and conductive hearing loss are the most common symptoms of OE.
ETIOLOGY
The two most common causes of otitis externa (OE) are related to trauma and water exposure. The most common mechanisms of trauma include cotton-tip applicators, fingernails, or foreign bodies. Organic foreign bodies are more irritating than nonorganic foreign bodies. Insects can be especially problematic. Water exposure may cause excessive retained moisture due to desquamation of squamous epithelium and retained cerumen, thus predisposing a child to OE. Anatomic factors such as canal exostoses may also predispose to water trapping. Approximately 30% of OE cases as associated with water exposure, 30% with ear canal trauma and 30% are idiopathic. The remaining 10% have less common etiologies, including skin disorders such as eczema or dermatitis. Occasionally, there may be an infection of the sebaceous glands of the outer third of the ear canal with formation of a furuncle, which is a small staphylococcal abscess with symptoms disproportionate to its size. Vesicles of the ear canal may be associated with herpes zoster infection. The most common organisms associated with OE are Staphylococcus aureus or Pseudomonas aeruginosa. Resistance to treatment may be due to an underlying fungal infection, frequently Candida albicans.
DIAGNOSIS
In its initial stages, otitis externa (OE) usually presents with itching and a sensation of fullness in the ear. This rapidly progresses to severe pain and associated ear discharge. Blockage of the external ear canal will cause a conductive hearing loss. Unlike acute otitis media (AOM), movement of the pinna will greatly exacerbate the pain. There may be associated pain with chewing. Fever is uncommon. On physical examination, there may be frank discharge from the ear, and visualization by otoscopy may be limited either because of pain or swelling of the external ear canal. In severe cases, the external ear canal may be completely closed. If a furuncle is present, there will be localized swelling and erythema with extreme pain on palpation of the affected area. Whenever possible, it is advisable to inspect the tympanic membrane to ensure that there is no underlying cause for the discharge, such as chronic suppurative otitis media (CSOM) or a perforation following AOM. This may not be possible at initial assessment because of edema of the external ear canal and associated pain on inspection. As such, follow-up examination is essential.
TREATMENT
Otitis externa (OE) requires prompt treatment of both the infective organism and the underlying cause. Foreign bodies should be removed, the use of cotton-tip applicators should be discontinued, and the patient should be advised not to swim. Debris in the ear canal should be removed. Patients should receive antibiotic eardrops that are effective against the presumed underlying organisms. Topical steroids may alleviate the inflammation, pain, and swelling. However, steroid drops should be discontinued in the presence of a fungal OE. Eardrops should be administered several times a day in the initial stages. If the external canal is extremely edematous, placement of a sponge or wick in this canal is useful to ensure antibiotic penetrance. Systemic antibiotics are also warranted if there is surrounding cellulitis of the soft tissues adjacent to the ear or cervical adenitis. Adequate analgesia is warranted, and in severe cases, narcotic administration may be justifiable.
If OE is unresponsive to initial treatment, a microbiologic sample for culture and sensitivity should be obtained. The most likely organisms under these circumstances are multiply drug-resistant P aeruginosaor fungi. Quinolone eardrops are usually the most effective treatment for Pseudomonas. Antifungal drops or creams are indicated for fungal OE. A furuncle may require topical and systemic antistaphylococcal antibiotics. If the abscess is pointing, then drainage with an 18-gauge needle may dramatically alleviate pain.
Once the acute infection has resolved, it is prudent to reassess the ear to ensure that there is no underlying predisposition to infection such as eczema or a cholesteatoma. In individuals predisposed to OE, prophylactic measures may be undertaken to prevent recurrence. This may include treatment of underlying skin conditions, regular toilet of the external ear canal to prevent water trapping, surgical removal of bony exostoses, and use of alcohol eardrops after swimming to promote drainage of water from the ear.
COMPLICATIONS
Recurrent otitis externa (OE) may be due to canal stenosis, which requires surgical intervention. Rarely, there may be cerumen and squamous epithelial retention with ballooning of the bony ear canal (keratitis obturans). This may also be associated with an underlying ciliary dyskinesia or congenital or acquired narrowing of the ear canal. The most serious complication is the development of necrotizing or “malignant” OE. This is often seen in patients who are diabetic or immunocompromised, and the offending organism is often pseudomonas. The infection spreads via the fissures of Santorini, causing osteomyelitis of the skull base. This osteomyelitis presents with pain and possible cranial nerve palsies. Patients who do not receive appropriate treatment have a high mortality rate.
CHONDRITIS AND PERICHONDRITIS
Perichondritis is an infection of the perichondrium of the auricular cartilage (Fig. 369-9). Infection typically follows local trauma (eg, ear piercing, burns, or lacerations). Occasionally, when the infection spreads down to the cartilage of the pinna itself, patients may also have chondritis (eFig. 369.4 ). The infection may closely resemble auricular cellulitis, with erythema, swelling, and extreme tenderness of the pinna, although the lobule is less often involved in perichondritis. The most common pathogens are P aeruginosa and S aureus, although other gram-negative and gram-positive organisms are occasionally involved. Treatment consists of systemic antibiotics active against both P aeruginosa and S aureus. An antipseudomonal penicillin or a combination of a penicillinase-resistant penicillin plus an antipseudomonal quinolone is typically used. Incision and drainage may be helpful for culture and for resolution of infection, which often takes weeks. If perichondritis fails to respond to adequate antimicrobial therapy, or is relapsing, a noninfectious inflammatory etiology should be considered such as relapsing polychondritis associated with rheumatologic disorders.
EAR TRAUMA
EXTERNAL EAR
Blunt trauma to the auricle is a common injury sustained during athletic activities and routine childhood play. These injuries are best prevented with the routine use of bike helmets and sport-specific head protection. Because of the thin skin covering and delicate perichondrium, hematomas and seromas of the auricle are common. When undiagnosed or untreated, these injuries can result in auricular cartilage damage and auricular deformity. Appropriate treatment consists of drainage of the fluid collection and subsequent application of a pressure dressing to prevent reaccumulation of fluid. The child should be reevaluated at close intervals for signs of perichondritis. The use of prophylactic broad-spectrum antibiotics may be indicated.
Penetrating trauma to the ear (most commonly, bite wounds) requires repair of the soft tissue defect and prophylactic antibiotic treatment. Because perichondritis is a significant risk that can cause necrosis of cartilage and substantial auricular deformity, close patient follow-up is necessary. In rare cases of subtotal avulsion with extensively exposed auricular cartilage and cartilage of questionable viability, hyperbaric oxygen treatment may be considered.
Frostbite injuries to the auricle are common in colder climates and should be treated by re-warming the affected area using warm, sterile saline-soaked gauze. Following this, treatment of the area should be similar to treatment of a burn, using topical sulfadiazine and analgesics. Close follow-up for signs of chondritis is essential. If burns of the auricle are superficial, they may require only topical treatment with sulfadiazine. More extensive burns may require debridement, systemic antibiotics, and soft tissue reconstruction.
Trauma to the external auditory canal usually involves foreign objects inserted into the canal. Laceration of the canal skin may require analgesics but may not require any specific treatment. In the primary care setting, foreign bodies in the cartilaginous portion of the canal can typically be removed. Those located medially in the canal or abutting the tympanic membrane are difficult to remove and generally require an operating microscope, suction, and specific otologic instruments. Following removal of the foreign body, a complete exam of the external auditory canal and tympanic membrane is necessary to rule out perforation.
Figure 369-9. Perichondritis of the ear. The pina is swollen and erythematous. There is no concomitant otitis externa, mastoiditis, or furuncle. (Source: Knoop KJ, Stack LB, Storrow AB, Thurman RJ. The Atlas of Emergency Medicine. 3rd ed. New York: McGraw-Hill; 2010. Photo contributor: Lawrence B. Stack, MD.)
MIDDLE EAR
Traumatic injuries of the middle ear are often caused by direct trauma via the external auditory canal. The mechanisms of these injuries include foreign body insertion in the external auditory canal or “slapping” of the ears. Tympanic membrane perforation may result in pain, bloody drainage, and hearing loss. Although these traumatic perforations typically heal over 3 to 4 weeks, trauma can also induce a middle ear effusion and/or hemotympanum behind an intact tympanic membrane. Such middle ear effusions clear spontaneously over the course of 10 to 14 days without treatment; however, careful examination and audiologic testing should be performed to rule out ossicular damage. In cases in which there is a significant and persisting conductive hearing loss, middle ear exploration may be indicated to identify and correct an ossicular discontinuity. Very rarely, severe trauma results in subluxation of the stapes footplate into the vestibule of the inner ear. Such patients present with sensorineural hearing loss (SNHL) and vertigo, and may require surgical intervention.
Barotrauma to the middle ear may result from scuba diving, routine plane flights, or even from excessively strong Valsalva-type maneuvers such as sneezing or coughing. Common findings after barotrauma are a middle ear effusion or hemotympanum. Less frequently, barotrauma may cause damage to the oval or round windows, resulting in leakage of perilymphatic fluid, called perilymph fistula. These patients may present with SNHL with or without vertigo. Perilymphatic fistulas are difficult to demonstrate intraoperatively and are often treated empirically after ruling out other pathologies.
Injury to the facial nerve via middle ear trauma is exceedingly rare. It most commonly occurs secondary to temporal bone fractures with resultant middle ear and mastoid trauma. For a patient presenting with a history or signs of middle ear trauma and facial paralysis, audiologic testing, temporal bone imaging, and immediate middle ear exploration may be warranted.
INNER EAR
Trauma to the inner ear structures can occur in association with severe blunt head trauma and temporal bone fracture. Approximately 75% of temporal bone fractures are longitudinal, with the fracture line running along the long axis of the petrous bone; the remaining 25% of these fractures are transverse. Although 20% of longitudinal fractures are associated with facial nerve injuries, up to 80% of transverse fractures may be associated with such injuries. Fractures through the cochlear or vestibular structures of the inner ear often cause symptoms of sudden SNHL and vertigo, and can be difficult to evaluate in severely injured or cognitively impaired patients. Longitudinal fractures are commonly associated with fracture lines that cross the external auditory canal and/or tympanic membrane, resulting in bloody otorrhea or hemotympanum. Conductive hearing loss secondary to ossicular disruption or fluid (ie, cerebral spinal fluid [CSF] or blood) may also result from trauma. Management of CSF and some facial nerve injuries may require immediate middle cranial fossa and middle ear/mastoid exploration, whereas other problems such as ossicular discontinuity and tympanic membrane perforations must wait until the patient can tolerate an elective procedure.
Barotrauma can also cause inner ear damage by inducing a perilymph fistula. Symptoms of vertigo or worsening hearing loss during times of intracranial pressure (eg, straining or Valsalva) are typical characteristics of perilymphatic fistula. Surgically placing soft tissue “patches” over the oval and round windows provides a simple yet effective treatment for these patients.