Neurophysiological evaluation of trigeminal and facial nerves in patients with chronic inflammatory demyelinating polyneuropathy.

Cranial neuropathy is clinically uncommon in patients with chronic inflammatory demyelinating polyneuropathy (CIDP), but there is little information on the neurophysiological examination of cranial nerve involvement. To determine the incidence of trigeminal and facial nerve involvement in patients with CIDP, the direct response of the orbicularis oculi muscle to percutaneous electric stimulation of the facial nerve and the blink reflex (induced by stimulation of the supraorbital nerve) were examined in 20 CIDP patients. The latency of the direct response was increased in 12 patients (60%) and an abnormal blink reflex was observed in 17 patients (85%). There was no correlation between electrophysiological findings and the latencies of the direct and R1 responses and disease duration or clinical grade in CIDP patients. Nevertheless, the prevalence of subclinical trigeminal and facial neuropathy is extremely high in patients with CIDP when examined by neurophysiological tests.