Dynamic F waves in neurogenic claudication.

Serial F waves were elicited before and after ambulation in 2 patients with neurogenic claudication. In both patients dynamic changes in F wave parameters consisting of either unelicitability or increased latencies occurred postexercise. The time course of these changes and their subsequent rapid reversibility over 15 minutes suggest ischemic-induced conduction block and slowing in proximal motor axons. These physiological changes may account for some of the dynamic neurological symptoms of this disorder. Moreover, F wave exercise testing may provide corroborative information for the diagnosis of neurogenic claudication.