Intrapartum injury (n = 4, 8%), diabetes (n = 2, 3%), herpes zoster (n = 1, 2%), or unknown (n = 4, 5%) was seen in the remainder.Īmong the remaining 111 cases, lumbosacral radiculopathy or sciatic neuropathy could not be excluded based on electrodiagnostic studies, and no firm sacral plexus localization was possible.

Vasculitis, viral, and autoimmune disorders were suspected to underlie the former, while the latter were seen following lumbar laminectomy, and aortic or cardiac surgery. Trauma, including motorcycle or motor vehicle accidents, gunshot wounds, and falls, was the 2nd most common cause of plexopathy, followed by idiopathic (n = 10, 17%) and iatrogenic (n = 8, 14%) etiologies. Using the above EMG guidelines, 60 patients (35%) had abnormalities localizing to the sacral plexus, most often due to cancer, usually gynecologic, colorectal, or prostatic, and including direct tumor invasion, radiation, or chemotherapy associated injury. Electrodiagnosis of sacral plexopathy was confirmed by EMG if patients demonstrated: (a) absent or reduced sural or superficial peroneal sensory amplitudes, (b) denervation potentials in muscles innervated by the sacral plexus but not by the sciatic nerve, and (c) normal paraspinal muscle EMG. All patients experienced leg weakness, usually manifested as foot drop, hip, leg, or back pain, and occasionally distal sensory loss. Each patient had been evaluated clinically, and electrodiagnostically by nerve conduction studies and needle electromyography (EMG). 2007 35 725-729.Īre electrodiagnostic studies useful in the diagnosis of sacral plexopathy, allowing one to differentiate the former from sciatic neuropathy or radiculopathy? Retrospective review of 171 cases of suspected sacral plexopathy, seen at the Cleveland Clinic Foundation between 1975-2005, was undertaken to address this question. Pitfalls in the electrodiagnostic studies of sacral plexopathies.

Clinical examination and imaging provide more useful information. Synopsis: EMG studies are helpful in a minority of patients with suspected sacral plexopathy. Rubin is on the speaker's bureau for Athena Diagnostics, and does research for Pfizer and Merck. By Michael Rubin, MD, Professor of Clinical Neurology, NewYork-Presbyterian Hospital, Weill Cornell Medical Center.

Emg sciatic nerve