The Diagnostic Value of the F-wave in Patients with Lumbosacral Radiculopathy

ABSTRACT

OBJECTIVE: The purpose of this study was to examine the sensitivity and characteristics of F-wave abnormalities detected by various parameters in patients with lumbosacral radiculopathies and to evaluate the relationship of F-wave with needle EMG. METHOD: The study was performed on 37 patients with lumbosacral disc herniation, which was confirmed by MRI and the patients with clinical lumbosacral radiculopathies (single lesion of L5 in 28 cases, S1 in 1 case, double lesion of L5 and S1 in 8 cases). F-waves were recorded by stimulating peroneal and tibial nerves at the ankle. Minimal latency (F min), maximal latency (F max), latency difference between F min and F max (F dif), mean duration (F dur) and side to side difference between sides in F min and F max were measured. Conventional nerve conduction study and needle EMG were also examined. RESULTS: The abnormal parameters of F-wave were so varied that the results could not lead any apparent conclusions as to which parameters were the most sensitive. However, F min and F dur seemed to be abnormal more frequently than F max and F dif. While the needle EMG showed abnormalities in 28 patients (75.7%), at least one of the different F-wave parameters was found to be abnormal in 18 patients (48.6%). Moreover, no significant relationship was observed between the abnormal findings of EMG and F-wave (p>0.05). CONCLUSION: The conventional needle EMG appears to be the more useful electrophysiological technique in the diagnosis of lumbosacral radiculopathies. Concerning the additional usefulness of F-wave, further study will be necessary.