Porphyric polyneuropathy and its pathogenesis in the light of electrophysiological investigations.

Twenty-four patients with acute intermittent porphyria were examined by means of routine electromyographic (EMG) tests, measurements of motor and sensory conduction in peripheral nerves and stimulation fatigue tests. The EMG results gave evidence of an initial, reversible disorder of function of the peripheral neuron, only sometimes followed by evidence of axonal degeneration of the "dying back" type. In stimulation fatigue tests there was some evidence of potentiation but none of fatigue. Attention is drawn to some analogies between the electrophysiological changes in porphyric polyneuropathy and in botulism. It seems that the pathogenesis of porphyric polyneuropathy may be dependent upon a block of cholinergic endings.