The most sensitive nerves and parameters in electrodiagnosis of polyneuropathies. Issue 3 (March 2016) - Jacobsen, A.B.
Abstract : Objective: To examine the most sensitive nerve and parameter in polyneuropathy electrodiagnosis. Methods: A total of 157 consecutive patients diagnosed with polyneuropathy were included. In all patients, bilateral peroneal and tibial motor nerve conduction studies (NCSs) and sural sensory NCSs with surface electrodes and near-nerve technique. (NNT) were done. The sensitivities were compared using chi-square statistics. Results: Sural NCSs with NNT was more sensitive than surface NCSs for conduction velocity (CV) (29% versus 11%) and amplitude (80% versus 28%) ( p < 0.01). F-wave latencies were more often abnormal in tibial (61%) than in peroneal (37%) nerve ( p < 0.01). CMAP amplitudes tended to be more frequently abnormal in peroneal (46%) than tibial (39%) nerves ( p = 0.08). Distal motor latency was equally sensitive in peroneal (28%) and tibial (31%) nerves similarly to CV, 58% and 60% respectively. Conclusion: Sural nerve amplitude with NNT is the most sensitive parameter in polyneuropathy electrodiagnosis. Tibial nerve F-wave latency is the most abnormal parameter when sural nerve is examined with surface electrodes only. Tibial nerve F-wave latency and peroneal and tibial CVs are the most common motor abnormalities. Key message: Sural nerve preferentially with needle electrodes should be examined in addition to motor nerves in polyneuropathy electrodiagnosis.