Electrodiagnostic abnormalities in 15 patients with posttraumatic syringomyelia: pre- and postoperative studies.

A review of 15 patients with posttraumatic syringomyelia indicates that the most reliable electrodiagnostic criteria for the diagnosis of syrinx are the loss of motor unit numbers with increase in motor unit amplitude and duration nd synchronous firing. Prolongation of F wave latency in a previously stable patient is a useful observation. Return of function and improvement of F wave latencies can occur rapidly following decompression of the syrinx. Forty per cent of the patients studied had concomitant involvement of at least one peripheral nerve as one would expect invoking the double crush hypothesis.