Phyllis A. Vallee and Christopher A. Lewandowski
The peripheral nervous system begins within the spinal canal with the ventral and dorsal nerve roots. These merge to form the spinal nerves, which then supply the visceral nerves, nerve plexuses, and peripheral nerves. Several generalizations can be made about the findings attributed to each of these areas. Lesions affecting the dorsal (afferent) roots produce pain, sensory loss, and decreased reflexes, but muscle strength is preserved. Ventral (efferent) root lesions produce muscle weakness, spasm, and autonomic symptoms without pain. A combination of all these symptoms occurs when spinal nerves are affected. Disorders affecting the visceral fibers will produce autonomic symptoms, which include extreme fluctuations in cardiac rhythm, blood pressure, gastrointestinal (GI) motility, urogenital function, sweating, and salivation.
Peripheral neuropathies are confusing entities; nevertheless, only 13% to 25% of patients undergoing intensive evaluation fail to have a diagnosis made (1,2). Emergency physicians evaluating patients complaining of symptoms consistent with peripheral neuropathy should determine the chronicity, pattern, and symmetry of symptoms to establish a working differential diagnosis (1,3,4). In general, peripheral neuropathies can be divided into several basic categories: polyneuropathy, plexopathy, radiculopathy, and mononeuropathy.
ACUTE POLYNEUROPATHY
Polyneuropathy results from the simultaneous dysfunction of multiple peripheral nerves. Symptoms include diffuse motor and/or sensory loss, with variable autonomic dysfunction. Polyneuropathies that develop over several days to 2 to 4 weeks are considered acute. Of these, Guillain–Barré syndrome (GBS) is the most common (4–6).
CLINICAL PRESENTATION
GBS, also known as acute inflammatory demyelinating polyradiculoneuropathy (AIDP), is a worldwide, nonseasonal, acute polyneuropathy that affects all ages, with a yearly incidence of 0.4 to 2.0 cases per 100,000 population (4,5,7,8). Pathologic examination reveals inflammation and segmental demyelination as the primary defect in about 90% of cases in North America and Europe (4,5,7,9). Primary axonal degeneration presenting as acute motor axonal neuropathy (AMAN) or acute motor and sensory axonal neuropathy (AMSAN) occurs in only 10% of cases in this region (7,9), but accounts for 30% to 65% of cases in China, Japan, Bangladesh, and Central and South America (5,9).
In classic GBS (AIDP), patients experience a prodromal event such as an upper respiratory tract infection, gastroenteritis surgery, vaccination, or infection with agents such as Mycoplasma, the herpes viruses, CMV, EBV, hepatitis B and C, and HIV. Overall, Campylobacter jejuni infection is the most commonly identified pathogen associated with GBS (4,5,8). In 1 to 3 weeks patients develop the onset of distal paresthesias and a symmetric ascending motor paralysis that progresses to its peak over 10 to 14 days. Motor weakness is both proximal and distal, with legs being involved prior to the arms and trunk. Additional findings include hyporeflexia or areflexia within 7 to 10 days of symptom onset, mild sensory losses, cranial nerve palsies (facial diplegia occurs in 50% of cases) (4), and autonomic dysfunction. Bowel and bladder disturbances are uncommon (15%) and brief in duration (4). Patients are afebrile and mental status is unaffected. It is not unusual for patients to initially present with low back, hip, and thigh pain that is confused with disc disease or lumbar strain.
The axonal variants of GBS (AMAN and AMSAN) tend to present in a more acute manner than AIDP and tend to have a worse prognosis (4). They also have a stronger association with preceding C. jejuniinfection. The Miller-Fisher variant of GBS presents with ophthalmoplegia, ataxia, and areflexia. Other less common variants include pure sensory GBS, pure pandysautonomia, and pharyngeal–cervical–brachial GBS. These variants may make diagnosis difficult; however, when considering the differential diagnosis of classic GBS, marked or persistent asymmetry of weakness, lack of facial and respiratory muscle weakness in a patient with generalized paralysis, prolonged incontinence, a sharp sensory level, or fever strongly suggest an alternative diagnosis (7).
DIFFERENTIAL DIAGNOSIS
Tick Paralysis
Tick paralysis typically affects children in the spring and summer months. An acute ascending motor paralysis nearly identical to GBS results from a toxin present in the saliva of ticks (usually Dermacentor in the United States) that have been attached to a human host for a period of 5 to 7 days. Unlike GBS, sensory loss and CSF abnormalities are not seen in tick paralysis (10). The diagnosis is made when the offending tick is located, and treatment consists of its removal and supportive care. Symptoms begin to improve within hours of tick removal and generally resolve completely within 2 to 3 days. Ixodes holocyclus, a tick species found in Australia, is associated with paralysis that can progress despite tick removal. For this species, a hyperimmune serum has been developed (1,10).
Botulism
Exposure to botulinum toxin, which inhibits the release of acetylcholine at neuromuscular junctions, usually results from the ingestion of improperly canned foods, GI tract colonization in young infants fed raw honey, or rarely, from cutaneous infection with Clostridium botulinum. The toxin is a potential weapon of mass terror, and exposure may be via ingestion or inhalation. Initial symptoms of botulism begin hours to several days after exposure and include nausea, vomiting, and dry mouth in patients who have ingested the toxin. Neurologic symptoms begin with cranial nerve palsies with prominent ocular findings (e.g., blurred vision, dilated pupils, diplopia). These are rapidly followed by symmetric, descending motor weakness and autonomic dysfunction. Sensation and mental status are not affected and fever is absent. Treatment consists of antitoxin therapy (available through the Centers for Disease Control [CDC]) and supportive care (1,10).
Poliomyelitis-Like Syndromes
In the United States, poliomyelitis is rare and nearly all cases are imported or related to the use of the live attenuated oral vaccine. Patients with polio first develop an acute viral illness with fever, headache, meningeal signs, muscle pain, and tenderness. These symptoms are present 1 to 2 days before weakness develops. Polio paralysis is more proximal than distal, legs are involved more than arms, and classically, involvement is asymmetric. Sensory loss is extremely rare, and its presence should raise the suspicion of other diagnoses. The most serious complication of polio is respiratory muscle paralysis. Progression of paralysis abates when patients become afebrile. A similar paralytic syndrome may occur following infection with other nonpolio enteroviruses or with the West Nile virus, a flavivirus introduced into the United States in 1999 (1,10,11).
Diphtheria
Diphtheria begins as a pharyngeal infection caused by an exotoxin-producing Corynebacterium diphtheriae. Subsequent toxicity, both cardiac and neurologic, correlates with the severity of the pharyngeal disease. Paralysis of local pharyngeal muscles, followed by cranial nerve palsies, occurs in the first or second week of infection. Cardiac toxicity begins 1 to 2 weeks after the onset of illness. The polyneuropathy, which is mainly motor, does not develop for 5 to 8 weeks. Weakness may begin in all extremities simultaneously, or it may first appear in proximal muscles and then spread distally. Occasionally, the primary site of infection is a skin wound, in which case sensorimotor changes are first noted near the infected wound. Treatment of diphtheria involves use of antitoxin within the first 48 hours of acute infection. Treatment of the neuropathy consists of supportive care (4,10).
Acute Intermittent Porphyria
In this disorder, stimulation of an enzymatically deficient heme synthesis pathway results in the buildup of neurotoxic precursors. An acute attack classically begins with severe abdominal pain, which is followed by tachycardia, hypertension, and mental status changes. Seizures may occur. Within days, a sensorimotor polyneuropathy that can be symmetric or asymmetric, and ascending or descending, may develop and can progress to respiratory failure and death. Treatment consists of intravenous glucose and hematin to shut down the defective pathway, β-blockers to control hypertension, and supportive care (1,4).
Heavy Metals/Toxins
Most neuropathies due to heavy metal poisoning are subacute or chronic. Acute presentations are associated with thallium, massive arsenic, and organophosphate exposure. Thallium ingestion produces abdominal pain, vomiting, and diarrhea, followed by painful paresthesias and the rapid onset of diffuse motor weakness. Differentiation from GBS is often made 1 to 2 weeks after the onset of symptoms, when thallium-induced alopecia becomes apparent. Acute arsenic polyneuropathy, which is also clinically similar to GBS, begins 8 to 20 days after a large exposure and is associated with GI symptoms, renal failure, hepatic failure, and mental status changes. Organophosphates initially produce a cholinergic syndrome, but in 2 to 5 weeks a predominantly motor, distal symmetrical polyneuropathy may develop (4).
Others
Acute polyneuropathy may develop as a complication of critical illness, uremia and dialysis, malignancy, nutritional deficiencies, collagen vascular disease, infectious agents, or a host of toxins and drugs. These should be considered in patients with a presumptive diagnosis of GBS.
Neurologic and muscular disorders that produce weakness and must be differentiated from GBS include myelopathy, transverse myelitis, lumbar disc disease, myasthenia gravis, and acute myopathy. Within this category, cervical myelopathy deserves added attention. It presents with an ascending paraplegia or quadriplegia and a sensory level. Unlike GBS, it is associated with localized neck pain or tenderness, hyperreflexia (unless spinal shock is present), pathologic reflexes (e.g., Hoffman sign), and loss of sphincter tone. Respiratory compromise is not seen unless the cord is involved above the C5 level. Active or passive neck motion may exacerbate symptoms. Acute myelopathy is usually the result of trauma. Subacute myelopathy is seen with neoplasm, subdural, or epidural abscess, disc herniation, and hematoma; however, these etiologies may present with acute onset of symptoms, especially if the vascular supply to the cord is compromised. Patients who have symptoms suggestive of a myelopathy must undergo rapid imaging with a magnetic resonance imaging (MRI) or computed tomography (CT) myelogram as correct diagnosis, and intervention may prevent permanent deficits.
Metabolic disorders such as acute hypophosphatemia, hypokalemia, hypermagnesemia, hyperkalemia, and periodic paralysis may produce severe generalized weakness that may mimic GBS. Hysteria and malingering should also be considered in the differential diagnosis.
ED EVALUATION AND MANAGEMENT
Patients presenting with the acute onset of weakness warrant rapid assessment of airway, ventilatory capacity, and cardiovascular status. Following stabilization, history and physical examination, including a detailed neurologic examination, are the principal methods of emergency department (ED) evaluation. The emergency physician should obtain a complete blood count, serum electrolytes, calcium, magnesium, phosphate, glucose, blood urea nitrogen, creatinine, chest radiograph, and electrocardiogram on all patients.
Additional studies might be obtained by the emergency physician if clinical evaluation raises the suspicion of a specific disease process. Otherwise, additional testing should be left to the consulting neurologist following characterization of the neuropathy by nerve conduction studies and electromyography (3).
Patients suspected of having GBS should undergo lumbar puncture. The characteristic findings are normal pressure and albuminocytologic dissociation (elevated protein levels with fewer than 10 mononuclear cells/μL). Cerebrospinal fluid changes may be delayed 1 to 2 weeks after the onset of symptoms. An increased cell count should raise the suspicion for HIV, West Nile virus, or Lyme disease as the precipitating event (1,4).
Baseline measurements of pulmonary function are important, because 25% to 33% of patients with GBS eventually require mechanical ventilation (1,4,5,9). Forced vital capacity (FVC) or negative inspiratory force (NIF) should be tested in the ED. A brief bedside test is to have the patient take a single deep inspiration and then quickly count for as long as possible; the ability to count to 20 correlates with an FVC of 1.5 L (4). FVC of <15 to 20 mL/kg or an IF of <20 to 30 cm H2O are indications of imminent respiratory failure and the need to initiate mechanical ventilation (1,4,5,12). Patients who remain in the ED for several hours should have serial pulmonary function testing. Bulbar muscle strength should also be followed, as intubation may be required to maintain a patent airway and prevent aspiration. Frequent vital signs and continuous cardiac monitoring are essential to identify life-threatening cardiovascular autonomic dysfunction. Blood-pressure fluctuations should be treated, as needed, with fluids and short-acting agents.
DISPOSITION
Every patient with an acute polyneuropathy should be evaluated by a neurologist. Admission to the hospital for further diagnostic studies and continued monitoring of vital signs and respiratory status is required. Whether an intensive care unit (ICU) is necessary for all patients is controversial. Any patient with significant respiratory impairment, inability to protect the airway, or autonomic instability should be admitted to an ICU. Several clinical findings have been associated with a high rate of mechanical ventilation: FVC <20 mL/kg, NIF <30 cm H2O, EF (expiratory force) <40 cm H2O, more than a 30% reduction in FVC from baseline, <7 days from symptom onset to hospital admission, and the inability to cough, stand, or lift the elbows or head off the bed (12,13). The presence of any of these should prompt an ICU admission. For all other patients, the admission destination depends on the adequacy of monitoring in other settings. Patients with severe or rapidly progressive GBS benefit from early plasma exchange or immune globulin therapy (1,3,4,5,9); therefore, these patients should be transferred to a facility capable of providing such therapies.
Although the majority of patients with GBS recover completely or with minimal deficits, it should be noted that GBS has a 3% to 5% mortality (4,5). Ten percent to 20% of patients will have severe persistent deficits (3,4,5,9). In addition, 5% to 10% will have recurrent episodes of acute peripheral neuropathy (4,14).
Common Pitfalls
• Mistaking the low back pain of GBS for disc disease or back strain.
• Mistaking the symptoms of cervical myelopathy or other spinal cord pathology for GBS.
• Failing to admit patients with minimal, but suggestive, symptomatology.
• Inadequately monitoring for respiratory and autonomic dysfunctions.
• Ascribing the symmetric weakness of GBS or other acute polyneuropathies to a psychiatric disorder.
• Failing to recognize variant presentations of GBS.
SUBACUTE POLYNEUROPATHY
CLINICAL PRESENTATION
Polyneuropathy that develops over a period of several weeks to months is said to be subacute; however, the distinction between subacute polyneuropathy (SPN) and acute polyneuropathy is not always clear. SPN may be symmetric or asymmetric. Symmetric disease generally begins with distal sensorimotor losses and tends to produce marked sensory impairment. Asymmetric SPN is frequently the result of neuronal ischemia; nerves are randomly affected, producing patchy sensorimotor losses.
DIFFERENTIAL DIAGNOSIS
The differential diagnosis of SPN includes subacute or chronic inflammatory demyelinating polyneuropathy (CIDP), mononeuritis multiplex, and other neuromuscular diseases that produce subacute weakness such as myelopathy, myasthenia gravis, amyotrophic lateral sclerosis, Parkinson disease, and depression. However, perhaps more important to consider are the numerous toxic, nutritional, and systemic disorders that can result in SPN.
The etiologies for symmetric SPN include diabetes mellitus, alcoholism, nutritional deficiencies, uremia, amyloidosis, heavy-metal intoxication, industrial solvents (e.g., glue sniffing), paraneoplastic syndromes, and a multitude of toxins and medications. Collagen vascular disease, autoimmune diseases, and infections such as Lyme disease and HIV are much less common causes.
The etiologies of asymmetric SPN include diabetes mellitus (e.g., diabetic amyotrophy), collagen vascular and autoimmune diseases, peripheral vascular disease, sarcoidosis, neoplastic disease, paraproteinemia, leprosy, Lyme disease, and HIV infection.
ED Evaluation and Management
History and physical examination are the principal methods of evaluation. Key historic elements to elicit are a history of neuromuscular or systemic disease, medications (prescription and nonprescription), and potential infectious or toxic exposure. Laboratory studies should include complete blood count, serum electrolytes, calcium, magnesium, phosphate, glucose, blood urea nitrogen, creatinine, and a screening chest radiograph. As with acute neuropathies, further studies should be obtained only if a specific etiology is suspected following initial evaluation (3).
If a medication is suspected as the etiology, it should be discontinued or changed after consultation with the primary care physician. Short-term follow-up should be arranged.
DISPOSITION
Most patients with SPN may be referred to their primary care physician for outpatient evaluation and referral to a neurologist. A recent review found that optimal, evidence-based, outpatient diagnostic tests are often not done (15); therefore, it may be of value to discuss these with the patient’s provider or mention them in discharge recommendations. These tests are as follows: glucose tolerance test, serum B12 with metabolites, and serum protein electrophoresis (2).
Common Pitfall
• Attributing SPN to a chronic medical condition, thus overlooking potentially treatable causes such as nutritional deficiencies, medication exposure, toxin exposure, infection, or vasculitis.
PLEXOPATHY AND RADICULOPATHY
CLINICAL PRESENTATION
A plexopathy is a disorder that affects the brachial or lumbosacral plexus. Symptoms include pain and mixed motor and sensory deficits in a pattern that cannot be attributed to individual peripheral nerves or nerve roots.
Acute or subacute plexopathies are associated with local trauma (e.g., shoulder dislocation), compression (e.g., retroperitoneal hematoma or abdominal aortic aneurysm), vascular disease (usually due to diabetes or collagen vascular disease), infection (e.g., Lyme disease), or they may be idiopathic. Idiopathic lumbosacral plexopathy is uncommon (16), but acute idiopathic brachial plexopathy (Parsonage–Turner syndrome) though rare is well described (4,17). It is seen most commonly in young adults with a slight male predominance, and there appears to be some association with recent viral illnesses and immunizations (1,17). Symptoms of brachial plexopathy begin with the sudden onset of severe shoulder pain that may extend into the neck and upper arm. Less commonly, the lower plexus cords may be affected, producing symptoms in the forearm and hand. Within days to weeks, motor weakness and sensory loss develop, usually coinciding with resolution of pain (11,17). About 90% of patients recover good neurologic function by 3 years (17). There is recent evidence to suggest that this syndrome is heterogeneous, including both plexopathy and multiple mononeuropathies (17,18). Chronic plexopathy is associated with infections, vascular disease, collagen vascular disease, tumor, infiltrative processes, and radiation therapy.
In contrast to plexopathy, a radiculopathy affects spinal nerve roots or spinal nerves. Symptoms include pain and sensorimotor deficits in a pattern consistent with the involved nerve root (e.g., lancinating pain along the L-5 nerve root dermatome). Frequently, several adjacent roots are affected, making differentiation from a plexopathy or multiple mononeuropathies clinically impossible. The etiologies of radiculopathy include all those of a plexopathy, as well as specific spinal canal or cord disorders such as herniated disc, spinal stenosis, and epidural tumor, abscess, hematoma, granuloma, and infection (1,4).
DIFFERENTIAL DIAGNOSIS
The differential diagnosis of plexopathy includes polyneuropathy, multiple mononeuropathies, and spinal cord and nerve root disorders. Brachial plexopathy can easily be confused with cervical radiculopathy, and lumbosacral plexopathy with lumbosacral radiculopathy. The pain of idiopathic brachial plexopathy tends to resolve as motor symptoms develop, unlike the persistent pain of cervical radiculopathy. In addition, pain from cervical radiculopathy increases with neck movement, coughing, and sneezing, whereas brachial plexopathy pain does not. Pain from both lumbosacral plexopathy and lumbosacral radiculopathy is persistent; however, back pain is not a prominent feature of lumbosacral plexopathy (16).
Thoracic outlet syndrome can mimic brachial plexopathy by producing pain and weakness in the arm. Other local joint or tendon disorders, muscular disorders, and amyotrophic lateral sclerosis may also mimic plexopathy but can usually be differentiated by their lack of sensory abnormalities. Abdominal or retroperitoneal processes may cause irritation and pain in a distribution consistent with either a radiculopathy or plexopathy.
ED EVALUATION AND MANAGEMENT
The history and physical examination, including a detailed neurologic examination, are essential in management decisions. Motor findings are more reliable than sensory findings when evaluating the upper extremity (14). The pattern of muscle weakness is unique for each nerve root (C5–T1) and peripheral nerve. In the lower extremity, the sensory examination is more reliable than the motor examination when evaluating root disorders (14). The lower extremity sensory examination reveals root dermatomes that run horizontally or diagonally across the anterior leg, whereas the peripheral nerve dermatomes run vertically. A plexopathy will produce a pattern of muscle and sensory deficits that are a blend of both root and peripheral nerve pathology. Patten’s Neurological Differential Diagnosis provides a detailed review of the complex clinical examination findings that will help differentiate spinal nerve root versus plexus versus peripheral nerve disorders (14).
Patients with symptoms of acute brachial plexopathy should have cervical spine, chest, and shoulder radiographs. Laboratory studies such as complete blood cell count, serum electrolytes, glucose, blood urea nitrogen, creatinine, and sedimentation rate should be obtained if the history or physical examination suggests infection, diabetes, or collagen vascular disease.
Acute lumbosacral plexopathy generally occurs secondary to another disease process. A complete blood cell count, serum electrolytes, glucose, blood urea nitrogen, creatinine, erythrocyte sedimentation rate, and lumbosacral films are appropriate. An abdominal ultrasound or CT is indicated if an aortic aneurysm or other retroperitoneal pathology (e.g., bleed, tumor) is suspected. A determination of postvoid residual urine volume will aid in defining the extent of the neurologic deficit.
The approach to an acute radiculopathy is dictated by the history and physical examination. Whereas an evaluation consistent with an acute herniated disc and no objective neurologic deficits may require only conservative management with analgesia, muscle relaxants, limited activity, and close follow-up, the presence of objective deficits or another etiology will require an aggressive evaluation, including blood testing, a determination of postvoid residual urine volume, spinal imaging, and consultation.
In patients with chronic symptoms, minimal immediate diagnostic workup is necessary. A chest and neck radiograph or lumbosacral films are reasonable screening tools for such patients.
DISPOSITION
Acute symptoms resulting from plexopathies are often difficult to distinguish from root and spinal cord disorders (4); therefore, they generally require urgent neurosurgical consultation. Spinal CT, MRI, or myelography may be required to determine the correct diagnosis, and hospital admission to complete such testing is recommended. Outpatient follow-up is appropriate for patients with chronic symptoms.
Common Pitfalls
• Attributing symptoms to mononeuropathy, and thereby failing to proceed with the appropriate diagnostic evaluation required for plexopathies and radiculopathies.
• Failing to consider potentially catastrophic etiologies for acute plexopathies (e.g., abdominal aneurysm).
• Failing to consider potentially catastrophic etiologies for acute radiculopathies (e.g., spinal epidural abscess or acute cord compression).
MONONEUROPATHY
CLINICAL PRESENTATION
Mononeuropathies produce variable symptoms of pain and sensorimotor loss in the distribution of a single peripheral nerve. Nerve compression (e.g., Saturday night palsy and meralgia paresthetica) and nerve entrapment (e.g., carpal tunnel syndrome) are the most frequently encountered etiologies for mononeuropathies seen in the ED. Entrapment syndromes have been associated with repetitive activity, pregnancy, rheumatoid arthritis, osteoarthritis, gout, hypothyroidism, acromegaly, amyloidosis, multiple myeloma, collagen vascular disease, and local tumors (5,15). Other causes of mononeuropathies are trauma, diabetes mellitus, peripheral vascular disease, collagen vascular disease, infection, granulomatous disease, infiltrative disorders, neoplasia, radiation therapy, and primary nerve tumors.
A unique form of mononeuropathy is mononeuritis multiplex. This entity involves the simultaneous or near-simultaneous dysfunction of two or more peripheral nerves. It may result from diabetes, multiple pressure palsies, infections (e.g., leprosy, Lyme disease, HIV infection), infiltrative or neoplastic disease, vascular disease, or collagen vascular disease (1). Overall, greater than 50% of cases result from systemic vasculitis of the vasa nervorum (4). Abrupt onset of mononeuritis multiplex in patients with a collagen vascular disease or other vasculitis generally indicates an acute necrotizing vasculitis that requires aggressive treatment (14).
DIFFERENTIAL DIAGNOSIS
The differential diagnosis of a mononeuropathy includes radiculopathy, plexopathy, polyneuropathy, local joint or muscular disorders, hysteria, and malingering.
ED EVALUATION AND MANAGEMENT
The evaluation of a mononeuropathy should focus on the nature of the deficit and historical factors such as duration, any traumatic injury, occupational factors (e.g., repetitive activity), or symptoms suggestive of diabetes, collagen vascular disease or vasculitis. The physical examination should determine whether the deficit fits the distribution of a single peripheral nerve. Provocative symptoms (e.g., Tinel sign and Phalen sign) may help elicit symptoms that are only episodic. Palpation along the course of the nerve may reveal areas of compression. Evidence of systemic disease should also be sought.
Complete blood cell count, electrolytes, blood glucose, erythrocyte sedimentation rate, antinuclear antibody testing, thyroid function tests, and serum protein electrophoresis are indicated only if a systemic disorder is suspected. Radiographs may be helpful in cases associated with trauma or when bone abnormalities are a possible cause of entrapment.
Identified etiologies, such as diabetes or repetitive activities, should be addressed. Patients with symptoms consistent with carpal tunnel syndrome may benefit from use of wrist cock-up splints.
DISPOSITION
Most patients with a mononeuropathy can be discharged with outpatient follow-up. Patients in whom the etiology is unclear should be referred to their primary care physician or a neurologist for further testing, which may include nerve conduction studies and electromyography.
Urgent evaluation by a plastic surgeon, orthopedic surgeon, or neurosurgeon is indicated for posttraumatic mononeuropathy. Hospital admission is indicated for acute mononeuropathy multiplex in patients with known or suspected collagen vascular disease or vasculitis because this disorder usually indicates an acute necrotizing vasculitis, which requires aggressive steroid or other immunosuppressive therapy (15,19).
Common Pitfalls
• Failing to differentiate a mononeuropathy from a polyneuropathy, plexopathy, or radiculopathy.
• Failing to detect systemic signs of collagen vascular disease or other vasculitic disorder in patients with mononeuropathy multiplex.
KEY TESTING
Polyneuropathy:
• Acute onset: CBC, serum electrolyte, calcium, magnesium, phosphate, glucose, BUN, creatinine, lumbar puncture, CXR, EKG and pulmonary function testing
• Subacute onset: CBC, serum electrolyte, calcium, magnesium, phosphate, glucose, BUN, creatinine, lumbar puncture, CXR
Plexopathy:
• Acute Brachial Plexopathy: CXR, shoulder radiograph, cervical spine imaging
• Acute Lumbar Plexopathy: CBC, serum electrolyte, glucose, BUN, creatinine, ESR, lumbosacral spine imaging, postvoid residual urine volume
For All Peripheral Neuropathies:
• Testing done if clinical evaluation raises the suspicion of a specific disease process
• May include: MRI, CT scan, abdominal ultrasound, toxicology studies, thyroid studies, ESR, collagen vascular evaluation
CRITICAL INTERVENTIONS
• Perform rapid assessment of airway and ventilatory capacity, including measurements of pulmonary function, for patients with suspected GBS; repeat periodically and intubate when indicated.
• Perform lumbar puncture on patients suspected of having GBS.
• Recognize neurologic distribution (ascending vs. descending, proximal vs. distal, symmetric vs. asymmetric).
• Always consider and evaluate for the catastrophic causes of any acute radiculopathy or plexopathy.
• Admit patients with acute mononeuropathy multiplex and known or suspected collagen vascular disease or vasculitis.
• Elicit symptom onset, evolution of symptoms and prodromal illness or symptoms. Pay particular attention to medications and potential environmental, toxic or occupational exposures.
REFERENCES
1. Dyck PJ, Thomas PK, eds. Peripheral Neuropathy. 4th ed. Philadelphia, PA: Elsevier Saunders; 2005.
2. England JD, Gronseth GS, Franklin G, et al. Practice parameter: Evaluation of distal symmetric polyneuropathy: Role of laboratory and genetic testing (an evidence-based review). Neurology.2009;72:185–192.
3. Bromberg MB, Smith AG. Toward an efficient method to evaluate peripheral neuropathies. J Clin Neuromuscular Dis. 2002;3:172–182.
4. Ropper AH, Brown RH, eds. Adams and Victor’s Principles of Neurology. 9th ed. New York, NY: McGraw-Hill; 2009.
5. Yuki N, Hartung H. Guillain-Barre syndrome. N Engl J Med. 2012;366:2294–2304.
6. Crone C, Krarup C. Diagnosis of acute neuropathies. J Neurol. 2007;254:1151–1169.
7. Cosi V, Versino M. Guillain-Barre syndrome. Neurol Sci. 2006;27:S47–S51.
8. Sejvar JJ, Kohl KS, Gidudu J, et al. Guillain-Barre syndrome and Fisher syndrome: Case definitions and guidelines for collection, analysis and presentation of immunization safety data. Vaccine.2011;29:599–612.
9. Hughes RA, Cornblath DR. Guillain-Barré syndrome. Lancet. 2005;366:1653–1666.
10. Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2010.
11. Peterson LR, Marfin AA, Gubler DJ. West Nile virus. JAMA. 2003;290:524–528.
12. Sharshar T, Chevret S, Bourdain F, et al. Early predictors of mechanical ventilation in Guillain-Barre syndrome. Crit Care Med. 2003;31:278–283.
13. Lawn ND, Fletcher DD, Henderson RD, et al. Anticipating mechanical ventilation in Guillain-Barre syndrome. Arch Neurol. 2001;58:893–898.
14. Patten J. Neurological Differential Diagnosis. 2nd ed. London: Springer-Verlag; 1996.
15. Callaghan B, McCammon R, Kerber K, et al. Tests and expenditures in the initial evaluation of peripheral neuropathy. Arch Intern Med. 2012;172(2):127–132.
16. Tarulli A, Rutkove SB. Lumbosacral plexitis. J Clin Neuromuscular Dis. 2005;7:72–78.
17. Tjoumakaris FP, Anakwenze OA, Kancherla V, Pulos N. Neuralgic amyotrophy (Parsonagae-Turner syndrome). J Am Acad Orthop Surg. 2012; 20:443–449.
18. Sumner AJ. Idiopathic brachial neuritis. Neurosurgery. 2009;65:A150–A152.
19. Vrancken AF, Hughes RA, Said G, et al. Immunosuppressive treatment for non-systemic vasculitic neuropathy. Cochrane Database Syst Rev. 2007;(1):CD006050.