Chapter 147. Chronic Neurologic Disorders

Acute ED management of these disorders centers on the care of acute respiratory failure as the most notable complication.

Clinical Features

Amyotrophic lateral sclerosis (ALS) causes progressive muscle atrophy and weakness. Upper motor neuron dysfunction causes limb spasticity, hyperreflexia, and emotional liability. Lower neuron dysfunction causes limb muscle weakness, atrophy, fasciculations, dysarthria, dysphagia, and difficulty in mastication. Symptoms are asymmetric. Patients may appear to have an acute compressive radiculopathy. Respiratory muscle weakness causes progressive respiratory depression.

Diagnosis and Differential

The diagnosis is suggested by upper and lower motor neuron dysfunction without other central nervous system dysfunction. The differential includes myasthenia gravis, diabetes, thyroid dysfunction, vitamin B12 deficiency, lead toxicity, vasculitis, and CNS or spinal cord tumors.

Emergency Department Care and Disposition

Respiratory failure, pneumonia, choking, and trauma are the common ED presentations. Optimize pulmonary function with nebulizer treatments, steroids, antibiotics, and intubation, as indicated. Admit patients with pneumonia or inability to handle secretions.

Clinical Features

Myasthenia gravis (MG) is characterized by muscle weakness and fatigue. Most MG patients have weakness of the proximal extremity muscles, neck extensors, and facial or bulbar muscles. Ptosis and diplopia are common presenting symptoms; 10% of patients have ocular muscle weakness only. Symptoms worsen as the day progresses and improve with rest. Severe respiratory muscle weakness causing respiratory failure is seen in myasthenic crisis.

Diagnosis and Differential

The differential for MG includes Lambert-Eaton, thyroid disorders, and stroke. MG is confirmed through administration of edrophonium, electromyogram, and serum testing for acetylcholine receptor antibodies. The edrophonium (Tensilon) test can differentiate a myasthenic crisis (inadequate treatment) from a cholinergic crisis (overmedication). Edrophonium has a rapid onset and short duration of action. First, a test dose of 1 to 2 milligrams IV is given and, if symptoms such as muscle weakness or respiratory depression worsen (cholinergic crisis), then the test is stopped. Emergent intubation may be necessary. Otherwise, the test is considered positive, indicating myasthenic crisis. Edrophonium can cause bradycardia, which responds to atropine.

Emergency Department Care and Disposition

MG is treated with airway management, avoidance of drugs that worsen MG, and administration of acetylcholinesterase inhibitors, high-dose steroids, plasmapheresis, or IV immunoglobulins.

1. Administer supplemental oxygen. Etomidate can be used if rapid sequence intubation is considered. Avoid depolarizing or nondepolarizing paralytic agents.

2. If the Tensilon test is positive, neostigmine should be given (0.5 to 2 milligrams IM, IV, SC or increments of 15 milligrams po). MG patients treated for other concerns should receive their usual cholinergic inhibitors.

3. Many drugs can exacerbate MG. Check carefully for drug interactions. Consult with a neurologist to aid in decision-making (Table 147-1).

Clinical Features

Multifocal areas of CNS demyelination causing motor, sensory, visual, and cerebellar dysfunction are seen in multiple sclerosis (MS). Types include relapsing and remitting (90%), relapsing and progressive, and chronically progressive. Lhermitte sign is described as an electric shock sensation going down into the arms or legs from neck flexion. Physical examination shows decreased strength, increased tone, hyperreflexia, clonus, decrease in vibratory sense and joint proprioception, and reduced pain and temperature sense. Increases in body temperature may worsen symptoms. Optic neuritis is the presenting symptom in 30% of cases and may cause an afferent papillary defect (Marcus-Gunn pupil). Acute or subacute central vision loss occurs over days and is usually unilateral. Retrobulbar or extraocular pain usually precedes vision loss. Internuclear ophthalmoplegia causes abnormal adduction and horizontal nystagmus, often bilaterally and is strongly suggestive of MS. Cognitive and emotional problems are common. Rarely, acute transverse myelitis occurs.

Diagnosis and Differential

The diagnosis is suggested by 2 or more episodes of neurologic dysfunction. MRI shows lesions including in the supratentorial white matter or periventricular areas. CSF protein and γ-globulin levels are often elevated. The differential includes SLE, Lyme disease, neurosyphilis, and HIV disease.

Emergency Department Care and Disposition

Treatment is directed at the complications of acute MS exacerbation. Consult a neurologist for care of a preexisting diagnosis and refer to a neurologist for new onset symptoms.

1. High-dose methylprednisolone has been shown to shorten duration of exacerbations.

2. Reduce fever to minimize symptoms and investigate for sources of infection. Evaluate for acute UTI or pyelonephritis; postvoid residuals >100 mL require intermittent catheterization.

3. Admit toxic-appearing patients with exacerbations requiring steroids or antibiotics.

Lambert-Eaton syndrome causes fluctuating proximal limb muscle weakness and fatigue and is seen mainly in older men with lung cancer. Strength improves with activity. Patients complain of myalgias, stiffness, paresthesias, metallic tastes, and autonomic symptoms. Eye movements are unaffected. Electromyography is abnormal, and serum tests are specific for antibodies to voltage-gated calcium channels. Treatment of the underlying neoplasm improves symptoms. Pyridostigmine and immunosuppressive drugs may reduce symptom severity.

Clinical Features

Parkinson's disease (PD) presents with 4 classic signs: resting tremor, cogwheel rigidity, bradykinesia or akinesia, and impaired posture and equilibrium. Initially, most patients complain of a unilateral resting arm tremor, described as “pill rolling,” which improves with intentional movement.

Diagnosis and Differential

The diagnosis is clinical and based on the presence of the 4 classic signs. Parkinsonism can result from street drugs, toxins, neuroleptic drugs, hydrocephalus, head trauma, and other rare neurologic disorders. Drug-induced PD most commonly presents with akinesia. No neuroimaging or laboratory study is pathognomonic.

Emergency Department Care and Disposition

Most patients are on medications that either increase central dopamine, are anticholinergics, or act as dopamine receptor agonists. Medication toxicity includes psychiatric or sleep disturbances, cardiac dysrhythmias, orthostatic hypotension, dyskinesias, and dystonia. With significant motor or psychiatric disturbances or decreased drug efficacy, a “drug holiday” for 1 week should be initiated in consultation with a neurologist.

Clinical Features

Poliomyelitis is caused by an enterovirus that induces paralysis by motor neuron destruction and muscle denervation and atrophy. Most patients have a mild viral syndrome and no paralysis. Major illness most commonly involves the spinal cord, resulting in asymmetric proximal limb weakness and flaccidity, absent tendon reflexes, and fasciculations. Maximal paralysis occurs within 5 days and is followed by muscle wasting. Autonomic dysfunction is common. Paralysis will resolve within the first year in nearly all patients. Other sequelae include bulbar polio (speech and swallowing dysfunction) and encephalitis. Polio is still endemic in Nigeria, Pakistan, Afghanistan, and India.

Postpolio syndrome is the recurrence of motor symptoms after a latent period of several decades. Symptoms may include muscle fatigue, joint pain, or weakness of new and previously affected muscle groups. Patients may have new bulbar, respiratory, or sleep difficulties.

Diagnosis and Differential

Polio should be considered in a patient with an acute febrile illness, aseptic meningitis, and asymmetric flaccid paralysis with loss of deep tendon reflexes and normal sensation. CSF shows a pleocytosis and positive cultures for poliovirus. Throat and rectal swabs are higher yield tests.

The differential diagnosis includes Guillain-Barré syndrome, peripheral neuropathies (eg, mononucleosis, Lyme disease, or porphyria), abnormal electrolyte levels, toxins, inflammatory myopathies, and other viruses (eg, Coxsackie, mumps, echo, and various enteroviruses).

Emergency Department Care and Disposition

Acute care is supportive. Lamotrigine may improve quality of life. Disposition should be made in consultation with a neurologist.