Proximal femoral conductions in patients with lumbosacral radiculoplexus neuropathy

Objectives Lumbosacral radiculoplexus neuropathy (DLRPN) is a rare form of neuropathy observed in diabetic and rarely non-diabetic patients. Pathophysiology and lesion location are not clearly understood. Our aim was to analyze proximal and distal femoral conductions in patients with DLRPN. Methods Six patients with DLRPN, 14 patients with diabetic polyneuropathy and 25 healthy subjects were included in the study. We performed L3 monopolar root stimulation and femoral nerve trunk stimulation at the inguinal region and calculated lumbar plexus conduction time by subtracting the latency of compound muscle action potential (CMAP) of the vastus medialis evoked by femoral nerve stimulation from the latency of CMAP of vastus medialis evoked by L3 root stimulation. Additionally peak to peak amplitudes and areas of CMAPs were analyzed. Results Electrophysiological examination showed that there was an axonal involvement in all patients with DLRPN. Prolonged lumbar plexus conduction time (in five extremities), and prolonged distal latency of the femoral nerve (in five extremities) probably due to secondary demyelination were also observed. Similar abnormalities were not observed in the diabetic polyneuropathy group. Conclusions DLRPN may affect different localizations on the peripheral nerves. L3 root stimulation may have an important role in the electrodiagnosis of DLRPN.