Tonic vibration reflex in Holmes-Adie syndrome: an electrophysiological study.

The pathophysiological mechanisms underlying benign areflexia were studied in six patients with Holmes-Adie syndrome. No impairment of sensory conduction velocity of sural nerve was found. A normal tonic vibration reflex was obtained in all patients. H reflex was absent in five patients, but responses like F waves were recorded in three subjects. These findings suggest that muscle spindles are not affected and that spinal motoneurone excitability is normal.