TRANSIENT RADICULAR NERVE-CONDUCTION BLOC K IN PATIENTS WITH INTERMITTENT NEUROGENIC CLAUDICATION

Patients with neurogenic claudication do not usually exhibit symptoms at rest. The diagnosis is uncertain when there are no signs of lumbar radiculopathy. However, the functional deficiary could show up during a brief time at presentation of the symptoms if appropriate electrophy siological techniques are used to measure nerve conduction at the radi cular segment. In 8 patients with neurogenic claudication, we examined the curve of recruitment of the soleus H reflex and in four of then t he chronodispersion of the F wave of the posterior tibial nerve, befor e and after walking was also examined. Both studies showed normal resu lts before walking in all patients. The H wave showed a transient dimi nution of excitability in 6 patients after walking, which lasted for a mean periof of 7 min. Only one of these patients also showed an incre ase in the chronodispersion of the F wave. Our data suggest that condu ction is transiently blocked in large myelinated fibers at a radicular level in patients with neurogenic claudication after walking. This co uld partially explain the symptoms of neurogenic claudication.