Study of motor and sensory nerve conduction velocities, late responses (F-wave and H-reflex) and somatosensory evoked potential in latent phase of intermittent acute porphyria.

Twenty-five patients of intermittent acute porphyria (IAP) in latent period were studied neurophysiologically by assessing motor and sensory nerve conduction velocities, late responses (F-wave and H-reflex) and somatosensory evoked potentials of median nerve and were compared with 15 age and sex matched control group. All the patients had at least one classical attack of IAP during which Watson Schwartz test was positive. None of them had any evidence of neurological defecit at the time of examination. Compared with the controls, patients of AIP had significantly slower motor and sensory conduction velocities of median nerve (P < 0.001) and it was more marked in the distal segment of the nerve. Nineteen out of 25 had one or the other abnormal neurophysiological parameter. Reduced nerve conduction velocity was not found to have any relation with age, sex or duration of the illness or number of attacks. Present study shows evidence of subclinical neuropathy in patients of intermittent acute porphyria in latent phase.