The illness usually resolves spontaneously, albeit slowly; 80% of patients recover normal function within 1 to 12 months. Twenty percent of patients are left with mild to moderate residual weakness. Some children will suffer acute relapse or chronic symptoms.
CIDP is an immune-mediated peripheral neuropathy and canaffect patients of all ages. Patients present with both proximal and distal weakness (usually in an episodic, relapsing-remitting pattern) affecting the extremities. Patients may alsoexperience sensation changes such as numbness, tingling, or pain. The diagnosis is clinical, although EMG or nerve biopsymay confirm the diagnosis. The mainstays of treatment forCIDP are IVIG, glucocorticoids, and plasmapheresis. Prognosis varies, with some patients undergoing complete remission, whereas others experience partial remission or severedisability.
HMSN (also called Charcot-Marie-Tooth Disease [CMT]) is a group of progressive peripheral nerve diseases. Motor components generally dominate the clinical picture, with sensation and autonomic functions affected later. The most common HMSN is CMT type 1A. Other forms may have milder symptoms. Some subtypes present with severe symptoms starting in infancy.
The peroneal and tibial nerves are the earliest and most severely affected. Most often, complaints begin in the preschool to early adolescent years, with weakness of the ankles and frequent tripping. Examination shows pes cavus deformity of the feet (high-arched feet), bilateral weakness of foot dorsiflexors, and normal sensation despite occasional complaints of paresthesia. Peripheral nerves can become markedly enlarged and may be palpable on exam. Progression of HMSN is slow, extending over years and decades. Eventually, patients develop weakness and atrophy of the entire lower legs and hands and mild to moderate sensory loss in the hands and feet. Some patients never have more than a mild foot deformity, loss of ankle reflexes, and electrophysiologic abnormalities. Others in the same family may be confined to a wheelchair and have difficulties performing everyday tasks with their hands.
HMSN can be either demyelinating (CMT1, with severelydecreased NCV and hypertrophic changes on sural nervebiopsy) or axonal (CMT2, with normal NCV but decreased action potential amplitudes and axonal degeneration onbiopsy). Specific genetic testing is available for many subtypes of HMSN. Specific treatment for HMSN is not available,but braces that maintain the feet in dorsiflexion can improvefunction.
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Tick paralysis produces an acute lower motor neuron pattern of weakness, clinically similar to Guillain-Barré syndrome. An attached female tick releases a toxin, similar to botulism, blocking neuromuscular transmission. Affected patients present with a severe generalized flaccid weakness, including ocular, papillary, and bulbar paralysis. A methodical search for an affixed tick, particularly in hairy areas, must be made in any child with acute weakness. Removal of the tick results in a prompt return of motor function.
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Myasthenia gravis is an autoimmune condition. Most commonly, antibodies block the acetylcholine receptors (AChR) at the neuromuscular junction, decreasing the number of effective receptors, which results in rapid fatigability of striated muscle, though other types of auto-antibodies exist. The three childhood varieties are juvenile myasthenia gravis in late infancy and childhood, transient neonatal myasthenia, and congenital myasthenia.