areflexia, without motor weakness of the extremities The most common cranial nerve deficit is a seventh (facial) nerve palsy, followed in decreasing frequency by impairment of cranial nerves IX, X, and XI and oculomotor abnormalities Autonomic dysfunction occurs commonly and results in blood pressure lability, postural hypotension, and cardiac abnormalities; autonomic dysfunction is a disproportionate cause of morbidity and mortality Urinary retention, if it occurs, is usually seen late in the illness As the paralysis ascends, muscles of breathing may become involved, leading to respiratory embarrassment The primary aid in diagnosis is LP, which demonstrates an elevated protein level and fewer than 10 white blood cells per cubic millimeter—the so-called albuminocytologic dissociation CSF glucose is normal The protein elevation occurs in almost all cases but may be delayed for weeks, usually peaking in the second or third week of illness Emergency electromyography (EMG) and nerve conduction velocity testing are not indicated EMG may detect the presence of nerve conduction velocity delay; however, it is usually not demonstrable until the second or third week of illness Contrast-enhanced MRI imaging has been shown to be a sensitive and useful diagnostic adjunct, and imaging will typically demonstrate enhancement of the spinal nerve roots Because of the potential for progression to life-threatening respiratory compromise, the child with Guillain–Barré syndrome should be hospitalized and observed closely Impending respiratory distress must be anticipated, and routine respiratory monitoring should be aided by specific measures of respiratory function, particularly measurement of negative inspiratory force Because autonomic dysfunction is common, blood pressure must be monitored closely and abnormalities treated vigorously Acute polyneuritis is generally self-limiting, with more than 90% of children in most series having complete or near-complete recovery In mild cases, in which children retain the ability to ambulate, only supportive care is required However, immunomodulatory therapy may be of benefit in more severely affected children Plasmapheresis and IV immunoglobulin both have been used Although wellcontrolled, blinded studies of these treatments in children are lacking, the available data suggest that both are effective in reducing the duration and severity of illness in those most severely affected Corticosteroids have not been shown to be beneficial in acute Guillain–Barré syndrome, and some evidence suggests they may actually delay recovery Myasthenia Gravis