CRITICAL ILLNESS POLYNEUROPATHY - CLINICAL FINDINGS AND OUTCOMES OF AFREQUENT CAUSE OF NEUROMUSCULAR WEANING FAILURE

Objective: To describe clinical and electrophysiologic features and ou tcomes of critically ill patients with neuromuscular causes of failure to wean from mechanical ventilator support. Design: A prospective, co nsecutive, case series. Setting: Neurological, neurosurgical, and medi cal intensive care units in a university hospital. Patients: Seven pat ients during a 3-yr period with failure to wean from mechanical ventil ation not explained by pulmonary complications. Interventions: Muscle and nerve biopsy in three patients. Measurements and Main Results: Det ailed electrodiagnostic studies were done in all patients 3 to 6 wks ( median 4.5) after the onset of the acute illness and were repeated 3 m onths to 3.5 yrs later in those patients who survived, primary illness es included various intracranial and medical conditions. All patients had moderate-to-severe limb weakness with marked muscle atrophy, Tendo n reflexes were decreased in three patients, exaggerated in two patien ts with intracranial lesions, and absent in two patients, Electromyogr aphy demonstrated severe acute denervation, with striking involvement of proximal muscles, Muscle and nerve biopsies showed severe neurogeni c atrophy and axonal degeneration without inflammation. There was no e vidence of primary myopathy. Two patients died of complications of sep sis, Of the survivors, three patients had no further weakness at the t ime of reexamination, except for peroneal nerve palsy in one patient, Two patients, still in the recovery period, showed markedly improved c onditions but still showed slight weakness of the proximal muscles. By electrophysiology, signs of chronic neurogenic damage were demonstrab le in all survivors at follow-up. Conclusions: Critical illness polyne uropathy is a frequent cause of neuromuscular weaning failure in criti cally ill patients, regardless of the type of primary illness, Involve ment of proximal (including facial and paraspinal) muscles is striking . Tendon reflexes are often preserved. Patients with central nervous s ystem injury may likewise develop critical illness polyneuropathy, In these latter patients, tendon reflexes may even be exaggerated, Recove ry from critical illness polyneuropathy is usually rapid and clinicall y complete, although incomplete on electrodiagnostic study. Residual p eripheral nerve lesion, generally of the peroneal nerve, is the most f requent feature of incomplete recovery, The need for careful electroph ysiologic testing is emphasized to clarify the nature and extent of ne uromuscular disturbances in critically ill patients, Failure to recogn ize the development of neuropathy in these patients may read to errone ous conclusions about the ability to wean them from the ventilator.