Electrodiagnostic / Neuromuscular Medicine
Abraham Ko, BA
Medical Student
Midwestern University, Arizona College of Osteopathic Medicine
Fullerton, California, United States
Edward Chang, DO
Resident Physician
University of California, Irvine
Orange, California, United States
Gilbert Hernandez, DO
Resident Physician
University of California, Irvine
Orange, California, United States
Anthony Nazaryan, DO
Resident Physician
University of California, Irvine
Glendale, California, United States
Bao Q. Tran, MD
Physician
University of California, Irvine
Orange, California, United States
Abraham Ko, BA
Midwestern University, Arizona College of Osteopathic Medicine
Cerritos, California, United States
Sciatic neuropathy, peroneal division
Case Description:
A 78-year-old male with atrial fibrillation, osteoarthritis, and prior lacunar stroke developed acute left foot drop following chiropractic manipulation. He reported eight weeks of sciatica-like pain that progressed to complete foot drop over one month. MRI revealed right L4-L5 disc extrusion with neuroforaminal narrowing, suggesting radiculopathy. On examination, there was complete loss of ankle dorsiflexion, eversion, and extensor hallucis longus function, with preserved inversion and plantarflexion. While electrodiagnostic workup had findings suggestive of remote multilevel L4-S1 radiculopathy, there was evidence of acute neuropathy in the left common peroneal division of the sciatic nerve. It was then isolated proximal to biceps femoris short head innervation, with findings of active denervation of all peroneal-innervated muscles. Electrodiagnostic studies, particularly examination of the biceps femoris short head, are crucial for differentiating sciatic neuropathy from lumbosacral radiculopathy in cases of acute foot drop. Accurate localization prevents diagnostic error and guides appropriate management.
Discussions: Sciatic neuropathy is the second most common neuropathy of the lower extremity, often presenting with foot drop and mimicking L5 radiculopathy or common fibular neuropathy. Because the fibular division has fewer fascicles and less supportive tissue, it is particularly vulnerable to injury and difficult to distinguish clinically. This case demonstrates the importance of comprehensive EMG protocols in foot drop evaluation. Testing the biceps femoris short head, though technically challenging due to its deep location, is essential because it is the only muscle proximal to the knee innervated by the fibular nerve. MRI alone may mislead; studies show MRI has higher sensitivity (74% vs. 54%) but lower specificity (39% vs. 61%) compared with EDX. Inclusion of the short head in EMG protocols improves diagnostic accuracy and prevents misattribution of imaging findings.
Conclusions:
