H-reflex recovery curve in syringomyelia

H-reflex recovery curves were obtained from 13 patients with cervical syringomyelia to assess motor neurone excitability, and results were compared with control subjects and patients with spasticity due to stroke. The median nerve was stimulated at the elbow and the H-reflex was recorded from the flexor carpi radialis muscle. Double pulses with interstimulus intervals ranging from 75 to 900 ms were delivered. The H-reflex was unobtainable from either limb in two patients with advanced disease and loss of all sensory modalities. H-reflex recovery curves from syrinx patients showed marked facilitation with interstimulus intervals ranging from 150 to 300 ms. Facilitation was higher than in patients with spasticity due to stroke. Results are indicative of an increased motor neurone excitability in patients with cervical syringomyelia.