Electrodiagnostic findings in acute porphyric neuropathy.

Of 115 patients with acute intermittent porphyria seen during a 20-year period, 11 had experienced an acute episode of quadriparesis. Nerve conduction studies performed on 8 of these 11 patients showed low-amplitude compound action potentials and normal velocity measurements. Needle electromyography demonstrated prominent fibrillation potentials, especially in proximal muscles. The changes in these findings with time confirm that this disorder is an acute axonal neuropathy.