Acute headache is a common chief complaint in the emergency department. Primary headache, such as migraine and cluster, is a condition in which headache is a primary manifestation and no underlying disease process is present. Secondary headache is a condition in which headache is a secondary manifestation of an underlying disease process. Most patients with acute headache have primary headache, particularly migraine. Performing an expensive battery of tests on all patients with acute headache is neither cost-effective nor appropriate. Failure to perform diagnostic tests in certain patients with acute headache, however, will result in failure to detect life-threatening, yet treatable, causes. The challenge to the clinician in the emergency setting is not to be lulled to sleep by the frequent migraine attacks and to remain vigilant for the other causes of acute headache.
Migraine is so common that many patients with a secondary headache have a history of migraine, making diagnosis in the acute setting quite difficult. Certain clues in the history and examination should lead to the performance of a diagnostic evaluation in search of the cause of secondary headache. The primary goals of the clinician treating a patient with acute headache are 3-fold: (1) diagnose the cause of headache, (2) provide emergency therapy, and (3) provide the patient with a means of long-term care. These goals apply for patients with primary or secondary headache. Primary headaches are chronic conditions that manifest as multiple acute attacks. Secondary headaches generally are caused by diseases that necessitate both urgent and prolonged care. This chapter deals with the diagnosis of acute headache. The diagnosis of chronic headache and therapy for conditions that cause headache are dealt with elsewhere in Chapter 21.
I. PATHOPHYSIOLOGY
The pathophysiology of head pain is likely the same no matter its cause. Among patients with brain tumor, patients with a past history of primary headache are more likely to have a tumor-related headache than those without a history of primary headache. Thus, the description of head pain alone is not a reliable predictor of whether a headache is primary or secondary. Hemicranial throbbing pain is not always a feature of migraine and can be a feature of intracranial disease. Dull aching head pain occurs in patients with primary headache and patients with brain tumors. Although current understanding of the cause of head pain is not complete, a plausible explanation of the pathophysiologic mechanism of headache that emphasizes the common final pathway of primary and secondary headaches is depicted in Figure 20.1. The schema provides an explanation for the “migrainous” characteristics of some secondary headaches.
II. HISTORY
A. A history of headaches, especially the relation of past headaches to the current headache, is the most important information needed to determine whether a diagnostic evaluation is necessary. A history of similar headaches for many years suggests a primary headache disorder. If, on the other hand, this headache is different in character from past headaches and especially if this is the first headache of the patient’s life, if this is the worst headache that the patient has had, or if the pain is persistent despite the use of measures that relieved previous headaches, a secondary headache is more likely (Table 20.1). If the patient has had similar headaches for only a few months, weeks, or days, then the possibility of secondary headache increases, and further investigation is warranted. Although it is common for the character of primary headache disorders to change throughout a lifetime, if the current headache differs from previous headaches, the clinician is obligated to investigate.
FIGURE 20.1 Plausible schema for pathophysiologic mechanism of headache depicts the common final pathway of primary and secondary headaches.
TABLE 20.1 Clinical Features Suggestive of Secondary Headache
Headache features
Different headache
First headache
Worst headache
Persistent headache
Exacerbation by head position
Onset
With Valsalva’s maneuver
With head trauma
After 50 years of age
Associated features
Focal neurologic signs (abnormal examination findings)
Change in consciousness
Fever
Seizure
Nuchal rigidity
Papilledema
Preretinal or retinal hemorrhages
History of
Bleeding diathesis
Hypercoagulable state
Cancer
Risk factors for HIV infection or AIDS
B. Age at onset of primary headache disorders is generally childhood to young adulthood. An age at onset older than 50 years is particularly suggestive of secondary headache.
C. Activity at onset of headache may suggest cause of headache. Although Valsalva’s maneuver, change in position, or head trauma can precipitate or exacerbate migraine, the presence of any of these features should raise the suspicion of secondary headache.
1. Valsalva’s maneuver may precipitate aneurysmal rupture and resultant subarachnoid hemorrhage (SAH). It can also precipitate or exacerbate a CSF leak and result in headache due to intracranial hypotension. Headache during coitus can occur as a result of aneurysmal rupture or as a result of coital migraine. The first time a person experiences coital headache, he or she needs a complete evaluation to rule out aneurysmal SAH.
2. Changes in position exacerbate several types of headache. Headaches worse in the supine position suggest increased intracranial pressure (ICP), for example, due to intracranial mass lesion, hydrocephalus, or cerebral venous thrombosis (CVT). Headaches worse when upright (and improved when supine) suggest decreased ICP due to a CSF leak. “Low-CSF-pressure headaches” are especially common after lumbar puncture (LP) but may occur spontaneously or after Valsalva’s maneuver. Mobile intraventricular tumors, such as third-ventricle colloid cyst, may cause intermittent hydrocephalus and headaches that occur only in a particular head position.
3. Head trauma can result in subdural hematoma but may also trigger migraines.
4. Exercise can precipitate migraine or another type of primary headache that is sensitive to indomethacin.
D. The characteristics of a headache are most helpful in determining whether the current headache is different from previous headaches experienced by the patient. Certain characteristics are suggestive of but not pathognomonic for certain causes of headache.
1. Severity of pain is important in that any patient who says he or she has “the worst headache of my life” needs an urgent and complete evaluation, with SAH highest in the differential diagnosis. Both primary headaches and secondary headaches, however, can manifest as very severe or very mild pain.
2. The time frame of onset of pain is more discriminating. Very rapid onset of headache suggests a sudden increase in ICP, particularly due to SAH. Mass lesions such as tumors, abscesses, and subacute or chronic subdural hematoma usually manifest gradually over days to months. Gradual onset of headache over minutes to hours is consistent with migraine. The headache of giant cell (temporal) arteritis tends to be subacute to chronic in presentation.
3. Duration of primary headaches is variable, although they typically last hours to days. Headaches that persist for longer periods despite treatment are worrisome and suggestive of secondary headache.
4. Location of headache and radiation of pain are nonspecific. Many posterior lesions cause frontal headache. Both primary and secondary headaches can be unilateral or bilateral. The pain of both migraine headaches and secondary headaches can radiate.
5. Quality of headache is nondiscriminating. Despite the traditional teaching that migraines must be pounding or throbbing, they are just as often pressure-like, squeezing, sharp, stabbing, or dull. Cluster headaches typically are described as boring, sharp, or lancinating, but so might the headaches associated with other pathologic processes.
6. Associated symptoms of the headache can offer important clues to the cause of headache (Table 20.1).
a. Nausea and vomiting are common features of migraine, but their presence in a person with new or sudden headache is worrisome because they suggest increased ICP or a posterior fossa lesion.
b. Photophobia and phonophobia can be part of migraine or a meningeal process such as SAH or meningitis.
c. Neck stiffness (anteroposterior nuchal rigidity) is typical of a meningeal process.
d. Change in consciousness rarely occurs in migraine, but its presence should alert the clinician to more serious causes of headache.
e. Focal neurologic symptoms (e.g., aphasia, visual symptoms, vertigo, ataxia, hemiparesis, or hemisensory deficit) can occur suddenly in association with headache in patients with stroke, seizure, subdural hematoma, and migraine. In this case, migraine is a diagnosis of exclusion, and the clinician is obliged to investigate for underlying disease. Transient ischemic attacks (TIAs) typically last 5 to 20 minutes. Stroke and subdural hematoma symptoms persist. Todd’s paralysis of partial seizures and the aura of migraine often last hours. Focal symptoms of ischemia or hemorrhage typically are “negative” and “static” (e.g., hemibody sensory loss), whereas focal symptoms of migraine typically are “positive” and “migratory” over minutes to hours (e.g., tingling in fingertips progressing to involve the ipsilateral hemibody). Partial seizures can result in symptoms that travel over seconds. Headache in a person older than 50 years with monocular blurred vision and a swollen optic disc suggests the anterior ischemic optic neuropathy (AION) of giant cell arteritis. Binocular visual symptoms can be migrainous or due to occipital pathologic conditions. Certain visual symptoms are classic for migraine, such as scintillating scotomata (blind areas surrounded by sparkling zigzag lines), photopsia (unformed flashes of light), and fortification spectra (slowly enlarging, sparkling, and serrated arcs).
f. Fever, diaphoresis, chills, or rigors suggest infection. Fever of any cause or generalized infection can cause headache, but if headache, neck stiffness, or decreased consciousness is a prominent symptom, meningitis is highest in the differential diagnosis.
E. Family history of headache is important yet extremely difficult to obtain when a patient has prominent pain, nausea, or cognitive dysfunction as can occur with either primary or secondary headache. Even if the patient is coherent or a relative is available, persons often are not aware of a family history of headache. Migraines tend to be most prominent in early adulthood, when children are too young to realize their parent has headaches, and the patient no longer lives under the same roof with parents or siblings. In addition, rationalization of relatives regarding the cause of headaches (e.g., “sinus” or “tension”) is usually believed by the patient, making a family history of “migraine” difficult to obtain.
III. PHYSICAL EXAMINATION
Physical examination may demonstrate signs of a disease that causes secondary headache. A detailed neurologic examination is particularly important; any subtle abnormality should be enough to stimulate a diagnostic evaluation (Table 20.1).
A. General examination.
1. Vital signs. Fever suggests an infectious cause of headache. The presence of arterial hypertension in a patient with headache is common but is rarely causative. Hypertension occurs as a result of migraine attacks, cerebral ischemia, and intracranial hemorrhage.
2. General appearance. Cachexia may be present among patients with chronic diseases such as cancer, AIDS, tuberculosis, and sarcoidosis. Headache due to tumor, abscess, granuloma, or meningitis may be the presenting symptom among such patients.
3. Head. Evidence of cranial trauma includes face and scalp abrasions and contusions and signs of skull fracture—depressed section of skull, Battle’s sign (postauricular ecchymosis), raccoon sign (periorbital ecchymosis), hemotympanum, CSF otorrhea, and CSF rhinorrhea. Skull tenderness to palpation can occur as a result of subdural hematoma. Poor dentition or dental abscesses may result in intracranial abscess. Although tenderness to palpation over the frontal sinus or maxillary sinus may suggest infection of these structures, migraine frequently results in external carotid territory vasodilatation with resultant sinus “fullness,” “pressure,” and tenderness. The presence of fever and purulent discharge from the sinuses is more helpful in diagnosing sinusitis. Tenderness to palpation over the mastoid process suggests mastoiditis, a possible precursor to CVT. Otoscopic examination may show ear infection as well as hemotympanum or otorrhea. Temporal tenderness or diminished temporal artery pulses in a person older than 50 years are consistent with giant cell arteritis. Auscultation of the skull may demonstrate cranial bruits that occur as a result of arteriovenous malformation (AVM).
4. Neck. Meningeal signs include anteroposterior nuchal rigidity, Kernig’s sign (inability to extend the knee after passive hip flexion in the supine position), and Brudzinski’s sign (involuntary hip flexion after passive flexion of the neck in the supine position) and imply the presence of meningitis or SAH. Evidence of neck trauma includes pain on lateral neck movement and neck immobility.
5. Skin. A petechial rash over the axillae, wrists, and ankles is consistent with meningitis due to meningococcus. Skin examination may reveal bruising suggestive of a bleeding diathesis, splinter hemorrhages of distal digits suggestive of cardioembolism, or lesions suggestive of a neurocutaneous disorder such as neurofibromatosis, tuberous sclerosis complex, or cutaneous angiomatosis; these conditions are associated with intracranial lesions that may cause headache. Melanoma suggests the possibility of cerebral metastasis causing headache. Lesions of Kaposi’s sarcoma are consistent with AIDS, which is associated with several intracranial diseases that cause headache.
6. Lymph nodes. Lymphadenopathy occurs among patients with cancer, AIDS, chronic infections, or chronic inflammatory diseases. The possible presence of any of these conditions should stimulate evaluation for a cause of secondary headache.
B. Neurologic examination. The neurologic findings are normal in patients with primary headache. A change in consciousness or focal deficit raises the possibility of secondary headache. The funduscopic examination may reveal papilledema in patients with ICP, AION in patients with giant cell arteritis, or preretinal hemorrhage in patients with intracranial hemorrhage. Headache in association with either partial third nerve palsy or complete but pupil-sparing third nerve palsy is worrisome because it suggests posterior communicating artery aneurysm. A patient with these findings needs urgent cerebral angiography—via catheter or computed tomography (CTA). The combination of proptosis, oculomotor findings, and headache suggests disease in the orbit, superior orbital fissure, or cavernous sinus; evaluation should be urgent. Acute glaucoma can manifest as headache, especially periorbitally. An injected conjunctiva and a hard globe are consistent with the diagnosis. Horner’s syndrome can occur in isolation ipsilateral to a carotid artery dissection.
IV. LABORATORY STUDIES
Laboratory studies are necessary in the evaluation of any patient believed to have a secondary headache (Fig. 20.2). There are no laboratories that identify primary headache.
A. Blood evaluation.
1. Complete blood cell count. Leukocytosis is consistent with infection, and marked leukocytosis is found in leukemia, which can cause headache through carcinomatous meningitis or cerebral venous occlusion. Leukopenia is found in AIDS. Anemia can occur in patients with cancer or giant cell arteritis. It also can be associated with a low-flow state that precipitates CVT. Essential thrombocythemia is a hypercoagulable state that can cause arterial or venous occlusions in the brain with resultant headache.
2. Chemistries. Renal failure can be associated with headache. Both renal function and liver enzyme abnormalities have implications regarding past drug use and options for future medical management. In general, however, abnormalities in serum chemistries may provide clues to a generalized, underlying disease process that can cause headache.
3. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are the initial tests to perform if giant cell arteritis is suspected. Moderate elevations in ESR (up to 50 mm per hour) are common among healthy elderly patients. Both ESR and CRP are nonspecific; elevations can be present in patients with infection, inflammatory disease, or cancer. Still, marked elevations of ESR or any elevation of CRP in a patient older than 50 years with new-onset headache should prompt administration of high-dose steroids and temporal artery biopsy.
FIGURE 20.2 Diagnostic algorithm for a patient with suspected acute secondary headache.
4. Prothrombin time and activated partial thromboplastin time may provide evidence of a bleeding diathesis that results in intracranial hemorrhage and headache.
5. Thyroid function tests. Thyroid disease can cause headache by serving as a trigger in a migraine patient or can cause headache by other mechanisms.
6. Hypercoagulable profile is indicated for patients with suspected CVT and for patients younger than 50 years with suspected ischemic stroke or TIA.
7. Arterial blood gas. Hypoxia can cause headache; arterial blood gas measurement should be performed if clinically indicated.
8. Drug screen. Use of sympathomimetic drugs such as cocaine and amphetamines can be associated with intracranial hemorrhage or cerebral ischemia and resultant headache. Salicylate toxicity can result in diffuse cerebral edema with headache worsening. The excessive use of analgesics, whether over-the-counter or narcotic, can cause medication-overuse (i.e., analgesic rebound) headache and interfere with acute headache management.
B. Urine evaluation may reveal nephrotic syndrome (which can be associated with a hypercoagulable state and resultant CVT), infection (organisms and WBCs), evidence of peripheral embolization (RBC casts), or use of illicit or analgesic drugs.
C. Radiography. A chest radiograph may reveal hilar adenopathy or pulmonary lesions that provide clues regarding the identity of intracranial lesions that cause headache. Radiographs of the cervical spine may reveal evidence of neck trauma.
D. A CT scan is a preferred initial cerebral imaging study because of convenience, ability to detect bony changes in head trauma, and sensitivity in the detection of acute blood. Noncontrast scanning is mandatory because both contrast material and blood present because of acute bleeding are white (hyperdense) on CT scans. If only a contrast scan is obtained, there may be confusion about whether a lesion is hemorrhage or an enhancing mass. With time, blood becomes increasingly dark on CT scans. Consequently, subacute (2 to 14 days) subdural hematoma is isodense with parenchyma on CT scans and may be difficult to detect. MRI is better in the detection of subacute bleeding. The odds of detecting SAH with CT decrease with time from the onset of symptoms. Within a few days, a large percentage of CT scans are normal. Even in the acute phase, at least 5% of patients with SAH have normal CT scans. For any patient with suspected SAH, if the CT findings are normal, the clinician is obliged to perform a LP. Once noncontrast CT is performed, if a mass lesion is suspected, a contrast scan should be obtained. Mass lesions such as tumors and abscesses disrupt the blood–brain barrier and cause seepage of contrast medium around or in the lesion. A mass lesion can be isodense with parenchyma on noncontrast CT scans and therefore difficult to detect. Contrast scanning greatly increases the chance of detecting such a lesion.
E. MRI is usually a secondary cerebral imaging procedure in the evaluation of acute headache due to inconvenience and a perception that it is unable to detect acute blood. With the advent of T2*-weighted imaging, however, MRI is now equivalent to CT in the detection of acute blood. Furthermore, it is superior to CT in the detection of subacute blood and is especially useful in examinations of patients with suspected subacute subdural hematoma. MRI is superior to CT and even angiography in the detection of vascular malformations. Any patient with suspected unruptured AVM as a cause of headache needs MRI. MRI is superior to CT in the detection of parenchymal lesions and the visualization of the posterior fossa and inferior temporal lobes. Unlike CT, MRI provides information regarding blood flow in cerebral vessels. MRI is the procedure of choice in examinations of patients with suspected CVT. It depicts both parenchymal and venous abnormalities and leads to a correct diagnosis of this condition approximately 75% of the time. In patients with intracranial hypotension and low-pressure headaches, MRI may demonstrate diffuse thickening of the pachymeninges with gadolinium enhancement, engorgement of venous sinuses, or subdural fluid collections.
F. Magnetic resonance angiography (MRA) is indicated in the evaluation of patients with suspected CVT who do not undergo conventional angiography. An MRA offers a noninvasive way of evaluating the cerebral vessels. In general, contrast medium is not necessary. It, however, can mislead the clinician if not performed and interpreted properly—vessels with abnormal flow are not depicted, slow flow can mimic occlusion, and subacute thrombus can mimic normal flow. Acquisition of images should be perpendicular to flow to avoid in-plane flow artifact. Selective MR venography (MRV) is performed by means of saturating arterial inflow.
G. LP.
1. Indications. LP for CSF analysis is indicated if one suspects acute or chronic meningitis, SAH, pseudotumor cerebri, or low-CSF-pressure headache.
2. Timing in relation to CT. It is preferable to perform CT before LP. If CT shows significant mass effect such as shift across the midline, obliterated basilar cisterns, or a compressed fourth ventricle, LP should be avoided to avoid precipitating uncal or central herniation of brain tissue through the foramen magnum. If CT shows SAH, LP is not necessary. If bacterial meningitis is suspected, antibiotics should be started on the way to CT, and LP performed after normal CT findings are obtained. If CT is to be delayed for hours and one suspects bacterial meningitis, it is necessary to treat the patient with appropriate antibiotics (and dexamethasone) even before CT and LP. The prognosis among patients with meningitis is heavily influenced by promptness of treatment.
3. CSF analysis. Opening pressure is most important in patients with suspected pseudotumor cerebri (generally >250 mm Hg) or low-CSF-pressure headaches. If SAH is suspected, one should obtain cell counts in the first and last tubes of CSF and test for xanthochromia. Knowing that the number of RBCs does not change significantly between the two tubes helps to confirm the diagnosis and avoids the common dilemma of determining whether or not a bloody tap is “traumatic.” Xanthochromia is the yellowish color of CSF supernatant that occurs because of either the presence of hemoglobin breakdown products or a very high-protein concentration. If the patient arrives for treatment days after a SAH, there may be no RBCs in the CSF, but xanthochromia due to hemoglobin breakdown persists for up to 2 weeks. Samples for culture of bacteria, fungus, and tuberculosis should be sent. Polymerase chain reaction is a sensitive means of determining the presence of infection. A Venereal Disease Research Laboratory test and cryptococcal antigen assessment should be performed as well. If cancer is suspected, at least 10 mL of fluid should be sent for cytologic analysis.
H. Cerebral angiography (catheter or CTA) should be performed urgently for any patient with evidence of SAH at CT or LP. A four-vessel arteriogram is mandatory because predictions of aneurysm location based on CT findings are not always accurate, and many patients have multiple aneurysms. Delayed venous-phase images may detect CVT, which can cause subarachnoid bleeding.
I. Electroencephalography is indicated if seizures are being considered, as in the evaluation of a patient with headache and associated loss of consciousness. Headaches often occur in association with seizures. Partial seizures can result in transient neurologic deficits and can be difficult to differentiate from migraine with aura and TIA.
V. DIFFERENTIAL DIAGNOSIS
A. Primary headache.
1. Migraine.
a. Definition. Migraine is a genetic condition in which a person has a predisposition to episodic headaches, gastrointestinal dysfunction, or neurologic dysfunction. Severe headache need not be a feature of migraine. The International Headache Society’s definition of migraine is quite specific for the purpose of research but is too limiting to be useful in clinical practice. Many investigators consider intermittent tension-type headache to be a form of migraine rather than a separate entity.
b. Triggers. A migraine attack occurs when a stimulus, or trigger, affects a person with the genetic predisposition to migraine. Examples of triggers are listed Figure 20.1. Women suffer more migraine attacks than do men because they are more frequently exposed to a trigger (estrogen level fluctuations of menstruation, pregnancy, oral contraceptives, and menopause), but they do not possess the gene more often than do men.
c. Phases. There are four main phases of migraine—prodrome, aura, pain, and postdrome. Not all phases need be present in any one migraine attack.
(1) The prodrome occurs hours to days before the headache and consists of mood changes (e.g., irritability and depression), excessive yawning, or food cravings (especially for chocolate, nuts, and bananas, mistakenly thought to be migraine triggers in the past).
(2) The aura can be visual, sensory, motor, or reflective of brainstem (e.g., vertigo and diplopia) or cerebral cortex (e.g., aphasia) involvement and occurs as a result of cortical spreading excitation and depression. As a consequence of the spreading chemical changes in the cortex, the symptoms typically migrate across the vision or body and progress from one type of symptom to another (e.g., floating or pulsating spots in the vision followed by hemibody tingling traveling down the body). The excitation phase leads to positive sensory symptoms such as photopsia and tingling. Visual symptoms can be any shape (spots, circles, wavy, or zigzag lines), any color (clear, silver, black, white, or brightly colored), and hemianopic or present throughout the visual field. An aura may be the only symptom of a migraine attack (aura without headache and acephalgic migraine); may occur before, during, or after the headache (headache with aura and classic migraine); or may not be present at all (headache without aura and common migraine).
(3) The pain of migraine may be in the head, abdomen, or chest. The headache characteristics are not as helpful in diagnosis as is generally believed. Not all migraine attaches are characterized by severe, throbbing, hemicranial headache. Migraine headaches may be mild, squeezing, dull, or bilateral. Typically, the headache onset is gradual over minutes to hours, and duration is hours to a few days. It may be associated with nausea, vomiting, photophobia, phonophobia, kinesiophobia, osmophobia, thermophobia, or difficulty concentrating. Gastrointestinal symptoms such as abdominal cramping, flatulence, and diarrhea may predominate during this phase (“abdominal migraine”). Chest pain may predominate during migraine attacks (“precordial migraine”). Transient dysautonomia often occurs during this phase and results in blood pressure changes, usually hypertension, but occasionally hypotension and the syndrome of “syncopal migraine.”
(4) The postdrome is marked by malaise for several hours after the headache. Mood changes, impaired concentration, and scalp or muscle tenderness may also be present. Sleep often helps migraine attacks, and patients tend to crave rest in a dark, quiet room.
d. Difficulties in migraine diagnosis. Migraine is a purely historical diagnosis. Aided by folklore and advertising for over-the-counter medications, patients tend to believe their recurrent headaches are due to “sinus,” “tension,” or “regular” headache. It is often beneficial to educate the patient regarding migraine before obtaining a history. If there is any doubt in the clinician’s mind regarding the diagnosis of migraine, a diagnostic evaluation is necessary to rule out other causes of headache.
2. Cluster headache is much less common than migraine. It occurs primarily among men and manifests as severe, stabbing, periorbital pain with associated ipsilateral tearing, injected conjunctiva, nasal congestion, and rhinorrhea. Alcohol often precipitates attacks. The attacks occur most frequently at night, last 30 minutes to 3 hours, and can occur several times per day. Unlike patients with migraine, patients with cluster headaches prefer to pace and keep active during the attacks. The term cluster refers to the seasonal occurrence of multiple episodes over weeks to months with intermittent periods of remission. There are episodic and chronic forms. Cluster headache is now considered to be one of the trigeminal autonomic cephalalgias, along with paroxysmal hemicrania and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing.
B. Secondary headache.
1. SAH is the most important consideration in the evaluation of patients with a first or worst headache, yet it is frequently missed: 25% of patients with SAH are initially treated for another condition. Most patients with SAH have headache as the initial symptom. The headache is unilateral in 30% of patients, and findings at neurologic examination may be normal. Many patients (estimates range from 20% to 95%) have a milder sentinel headache that precedes the cataclysmic event. The clinician should consider the sentinel headache of SAH in the evaluation of patients with mild, yet different headaches. CT usually provides enough information for a diagnosis, but if SAH is suspected clinically and CT findings are normal, LP is mandatory. One should examine the CSF as described in IV.G. Once SAH is diagnosed with CT or LP, urgent CTA or four-vessel catheter angiography is required to identify aneurysms amenable to surgical clipping or coiling.
2. Meningitis, particularly bacterial and viral meningitis, often manifests as acute headache. Fever, neck stiffness, confusion, decreased consciousness, and cranial neuropathy may be present. Bacterial meningitis is fatal if the patient is not treated. Administration of broad-spectrum antibiotics should be started as soon as there is clinical suspicion—before CT and LP are performed. If one suspects bacterial meningitis, CSF analysis is mandatory. If CT can be performed within minutes, one should perform CT before LP to rule out mass effect. Section IV.G. describes steps to take if CT cannot be performed immediately. Antibiotic therapy can be adjusted once culture results are known.
Aseptic meningitis and chronic meningitis can also manifest as acute, persistent headache. Cranial neuropathy and radiculopathy are more common, and neck stiffness is less common in chronic meningitis. Conditions associated with chronic meningitis include syphilis, fungal infection (especially cryptococcus), tuberculosis, sarcoidosis, Lyme’s disease, cancer, and lymphoma. Any patient with AIDS who has a headache and normal findings at contrast CT of the brain needs LP in search of cryptococcal meningitis. Patients with suspected neoplastic meningitis may need several LPs for cytologic analysis of CSF before the diagnosis is confirmed.
3. Subdural hematoma occurs as a result of the tearing of bridging veins. When acute, it presents as a rapidly progressive neurologic deficit, but headache may be the only symptom of subacute or chronic subdural hematoma. Although subdural hematoma typically is caused by closed head trauma, in many cases a history of trauma is absent especially in older patients. CT usually provides enough information for the diagnosis, but blood from subacute bleeding (2 days to 2 weeks) is isodense with brain parenchyma on CT scans, making it difficult to detect. MRI is superior in the detection of subacute bleeding. Epidural hematoma caused by the rupture of a meningeal artery, often in association with skull fracture, usually manifests as rapidly progressive neurologic deficit and decreased consciousness rather than as headache. The classic sequence of head trauma, brief loss of consciousness, lucid interval, and rapid progression to coma occurs in less than one-third of patients.
4. Intracerebral hemorrhage manifests as focal neurologic findings and usually a change in consciousness or cognition. Estimates of headache incidence with intracerebral hemorrhage vary depending on the size and location of the hemorrhage. Among patients who are able to communicate, headache is more common with larger hemorrhage and hemorrhage in the cerebellum and cortex (lobar hemorrhage). Cerebellar hemorrhage presents with acute posterior headache, nausea, vomiting, and inability to stand. CT provides enough information for the diagnosis, and emergency surgery may be lifesaving.
5. Ischemic stroke and TIA always manifest as focal neurologic deficit. Headache occurs in 15% to 20% of patients with acute cerebral ischemia. The presence of headache with acute cerebral ischemia suggests at least temporary ischemia of the large artery territory, even if only a subcortical “lacunar” infarct is seen on CT scans or MR images (not all small-artery “occlusions” are caused by small-artery “disease”). Despite traditional teaching, it is unclear whether headaches are more common in association with cardioembolic rather than atherosclerotic stroke. CT findings often are normal in the first several hours of ischemic stroke. Stroke should be the first thought when a patient has an acute focal neurologic deficit with headache. Patients with acute focal brain or brainstem dysfunction, headache, and normal CT findings or CT scans that show focal hypodensity need a thorough evaluation for a cause of ischemic stroke or TIA. The evaluation should include assessment of cerebral arteries and the heart for a source of embolism and, in certain circumstances, assessment of the aorta and blood (hypercoagulability or vasculitis profile).
6. Cervicocephalic arterial dissection is often—but not always—associated with trauma. When trauma is the cause, symptoms may be delayed for several minutes to hours. Headache, facial pain, or neck pain may be the only symptom. Carotid dissection usually results in ipsilateral, steady, nonthrobbing headache, and ipsilateral Horner syndrome. Pain in the throat and focal cerebral ischemia are also prominent. Vertebrobasilar dissection causes occipital headache or neck pain and may be associated with neck manipulation or whiplash injury. Definitive diagnosis of arterial dissection requires MRI or cerebral angiography. The optimal MRI sequence is fat-saturation cervical MRI—axial view of the artery shows a circle of increased signal intensity (subintimal blood) surrounding a small area of low-signal intensity (normal flow in a narrowed lumen). At cerebral arteriography, the classic finding is a tapered narrowing or occlusion.
7. Giant cell arteritis is almost exclusively a disease of persons older than 50 years and is much more prevalent among those older than 60 years. It should be considered when any person older than 50 years has a persistent or new headache. The term temporal arteritis is misleading because this condition often affects the short posterior ciliary arteries of the eye and branches of the external carotid artery other than the temporal artery. It can also affect the cerebral and coronary arteries. Possible associated symptoms include visual loss (arteritic AION), temporal tenderness, weight loss, malaise, fever, chills, polymyalgia rheumatica, and jaw claudication. Anemia, leukocytosis, and elevated liver enzyme levels may be present. The CRP elevation is more sensitive and more specific than is ESR elevation. Definitive diagnosis is made by means of temporal artery biopsy. Administration of steroids should be started as soon as serologic results are known. Treatment does not affect biopsy results for at least 2 weeks. Because of the frequent presence of skip lesions, long segments of artery should be obtained, and bilateral biopsy may be necessary.
8. CVT is not rare, often goes unrecognized, and occurs as a consequence of a predisposing disease. Diffuse headache due to increased ICP may be the only symptom. Other common symptoms include seizure, focal neurologic deficit, and change in consciousness. Predisposing conditions fall into one of three categories—hypercoagulable state, low-flow state, and vessel wall abnormality. A personal or family history of venous or arterial thrombotic episodes suggests a primary hypercoagulable state. All patients with CVT should undergo a detailed hypercoagulable evaluation. Secondary hypercoagulable states include those associated with late pregnancy, the puerperium, and cancer. Low-flow states include dehydration, anemia, congestive heart failure, sickle cell disease, and compression of cerebral sinus by tumor. Vessel-wall abnormalities can be caused by trauma, infection, cancer, or inflammation. Because the cerebral sinuses lie in the midline, lesions often are bilateral and parasagittal. Venous edema, infarction, or hemorrhage can occur; edema and infarct cannot be differentiated at cerebral imaging. CT findings often are suggestive but are not enough to make a diagnosis. MRI and MRV are the diagnostic studies of choice. One can also make the diagnosis with conventional cerebral angiography and delayed venous images. CVT should be considered in the evaluation of any patient with a “pseudotumor” syndrome, especially men and thin women (see V.B.9.), any patient with headache and a history consistent with hypercoagulable state, and any patient with headache and bilateral “infarcts” or hemorrhages on cerebral images.
9. Idiopathic intracranial hypertension (pseudotumor cerebri) occurs mainly among young obese women. Diagnosis is based on the clinical findings of headache and papilledema, normal findings at cerebral imaging, and elevated opening CSF pressure (more than 250 mm Hg) at LP. Brain tumor and CVT in particular must be ruled out. Papilledema need not be present for diagnosis. The serious sequela of idiopathic intracranial hypertension is blindness due to chronic papilledema. Several drugs can cause intracranial hypertension, mimicking the idiopathic condition; these include tetracycline, aminoglycosides, and vitamin A. The syndrome of intracranial hypertension in a patient taking oral contraceptives should stimulate investigation for CVT because oral contraceptives can exacerbate or cause a hypercoagulable state.
10. Unruptured AVM can cause migraine headaches. If an apparent migraineur always has hemicranial headaches on the same side and there is no known family history of migraine, one should use MRI to rule out unruptured AVM. It is likely that ischemia or rapid changes in cerebral blood flow incite spreading cortical excitation/depression and a migraine attack.
11. Postcarotid endarterectomy headaches occur in approximately 40% of patients undergoing the procedure. Similarly, headaches may occur in patients who have had postcarotid angioplasty and stenting. The headache usually develops several hours to days after the procedure, is ipsilateral to the side of the revascularization, and resembles a migraine. Patients with a history of migraine may have a typical attack, and nausea may be present. Although the headache usually lasts only a few hours and the neurologic symptoms usually resolve without sequelae, a migrainous headache may herald the onset of reperfusion syndrome with ipsilateral vasogenic cerebral edema, seizures, and intracerebral hemorrhage. Patients with bilateral high-grade carotid stenoses and chronic cerebral hypoperfusion pre-procedure are at particular risk for reperfusion syndrome. As is the case with AVM, the rapid change in cerebral blood flow may incite spreading cortical excitation/depression and migrainous phenomena.
12. Bell’s palsy, idiopathic or herpetic mononeuropathy of cranial nerve VII, often is associated with retroauricular pain. Pain may be the first symptom and may be severe enough to be the patient’s chief symptom, rather than the ipsilateral facial weakness involving the forehead, eye closure, and lips.
13. Cerebral tumors and abscesses usually manifest similarly as gradually progressive headache over weeks to months. They may also be associated with gradually progressive neurologic deficit. Both primary brain tumors and metastatic lesions can occur acutely if associated with hemorrhage or seizure. Abscesses frequently cause seizures and can be associated with fever and other signs of sepsis. Any patient with a known history of cancer and new headache should be evaluated for cerebral metastasis. Colloid cysts of the third ventricle may manifest as positional headaches, as in II.C.2.
14. Dental abscesses usually manifest as oral or jaw pain, but if the patient is not treated, these abscesses may cause more diffuse headache.
15. Sinusitis is a much less common cause of acute headache than is generally imagined. A sensation of nasal congestion is common in migraine owing to vasodilatation in the external carotid territory; this can even cause clear nasal drainage or nose bleed. Surgery for sinusitis should not be undertaken to manage the headache alone because the headache associated with sinus congestion is usually due to migraine. The diagnosis of sinusitis is more likely if the headache is associated with fever, purulent nasal discharge, and increased densities in the sinuses on CT scans.
16. Trigeminal neuralgia usually is described as a sharp or burning pain rather than an ache and most commonly occurs unilaterally in the maxillary distribution of the trigeminal nerve. It can occur sporadically or represent a symptom of multiple sclerosis (see Chapter 40).
17. Low-CSF-pressure headache can occur when CSF pressure is abnormally low, as occurs after LP (post-LP headache) or after nerve root sleeve trauma and subsequent CSF leak. Symptoms typically resolve in the supine position and recur when the patient is upright.
18. Acute glaucoma often manifests as periorbital headache. Pupillary changes, conjunctival injection, lens clouding, and a globe hard to palpation are typical. Elevated intraocular pressure confirms the diagnosis.
19. Arterial hypertension, per se, does not cause headache. Rather, it often occurs as a result of a syndrome also associated with headache such as migraine, stroke, hypertensive encephalopathy, eclampsia, pheochromocytoma, or ingestion of cocaine, amphetamines, phenylpropanolamine, or monoamine oxidase inhibitors.
VI. DIAGNOSTIC APPROACH
The diagnosis of primary headache conditions is based on a supportive detailed history and normal findings at neurologic examination. If the clinician has any suspicion at all that the patient may be having a secondary headache, a series of diagnostic tests is indicated to determine the cause of headache. Many of the conditions that cause secondary headache are fatal or disabling if the patient is left untreated. Fortunately, in many cases, the conditions can be managed. Figure 20.2 depicts a diagnostic algorithm for patients with suspected acute secondary headache. If a patient has any one of the clinical features suggestive of secondary headache, the diagnostic evaluation should be undertaken, beginning with laboratories and noncontrast CT.
VII. REFERRAL
A. Primary headache. Migraine, cluster, “tension-type,” and medication-overuse (analgesic rebound) headaches are chronic conditions that manifest acutely. The proper management of primary headache conditions requires long-term care. Once the acute-care clinician diagnoses primary headache and offers emergency treatment, he or she is obligated to counsel the patient regarding the importance of long-term care and to refer the patient to a neurologist or generalist for definitive treatment. Increased patient education leads to improved patient care and lower health care costs by not spending emergency department resources on patients with recurrent headache.
B. Secondary headache. After initial diagnosis and emergency management, the definitive treatment of patients with secondary headache usually requires admission to the hospital and referral to a specialist. Neurointerventionalists and neurosurgeons care for patients with SAH, neurosurgeons for patients with subdural or epidural hematoma. Patients with intracranial masses need immediate referral to a neurologist and often a neurosurgeon as well. If the mass is a tumor, referral to a neuro-oncologist may be necessary and, if the mass is an abscess, referral to a specialist in infectious diseases is appropriate. Most patients with sinusitis and headache are best cared for by a generalist or infectious disease expert. Referral to an otolaryngologist is appropriate if surgery is deemed necessary. Acute-care clinicians should initiate treatment for patients who have suspected giant cell arteritis with high-dose steroids, then refer immediately to a neurologist or rheumatologist for long-term steroid therapy and an ophthalmologist or neurosurgeon for temporal artery biopsy. Patients with CVT need immediate referral to a neurologist or primary-care physician for anticoagulation and hypercoagulability evaluation and to an ophthalmologist to follow visual fields carefully and perform optic nerve sheath fenestration if necessary.
Recommended Readings
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