Introduction
Femoral nerves originate from the L2, L3, and L4 nerve roots and have muscular branches, as well as thigh sensory nerves of medial and intermedius area of thigh and saphenous nerve. Isolated femoral neuropathy rarely occurs due to abdomen, hip, or pelvis surgery or stretch stress, compression. Bilateral spontaneous femoral neuropathy is not reported yet. We present a case with spontaneous bilateral femoral neuropathies.
Case report
A 25-year old man admitted the neuropsychiatric inpatient clinic with drug intoxicification, with weakness of bilateral knee extensor. He had taken medication during several years for depression. He took overdose of medication for severe stress, at army recruit training center for beginning military service. And, he had slept more than 24 hours. After wake up, weakness of both lower extremities had developed. Electrodiagnostic study demonstrated bilateral femoral neuropathies with axonal injury (Table 1, 2). Two months later, his weakness showed partial improvement, and, follow up electrodiagnostic examination revealed partial electrodiagnostic recovery. D, L-spine magnetic resonance imaging (MRI) showed small loculated hematoma surrounded with left psoas and quadratus lumborum muscles. Hip MRI showed no abnormality of lumbosacral plexus and proximal sciatic nerve, but a change in signal intensity was observed in the left vastus intermedius, lateralis, psoas, and pectineus muscles (Figure 1). After 3 months of symptom onset, there was still difficulty in walking and stair up and down due to muscle weakness, and bilateral anterior thigh muscle atrophies, left side dominant, were observed. On the 204th day of symptom development, a third follow up electromyography was performed, and improved compared to previous examination. In the long-term follow up, symptoms improved and independent gait was possible.
Discussion
Femoral neuropathy has been rarely reported, and most cases are caused by external factors such as stretch and compression. In this case, small hematoma was observed in psoas and quadratus lumborum muscles, but it was not enough to cause nerve compression. The sleeping posture was also not the one causing the stretch. When patients complain of knee extensor weakness, spontaneous femoral neuropathy also needs to be in consideration. |
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Rt.: Right, Lt.: Left, EDB: Extensor digitorum brevis, TA: Tibialis anterior, LFCN: Lateral femoral cutaneous nerve, ms: millisecond, mV: millivolt, μV: microvolt, CV: conduction velocity, m/s: meter/second
IA: insertional activity, Fib: Fibrillation, PSW: Positive sharp wave, MUAP: motor unit action potential, NL: normal, Poly: Polyphasic
Figure 1. Magnetic resonance T2 weighted image showing loculated hematoma (arrow) surrounded with psoas and quadratus lumborum muscles, focal muscle fiber tear, and strain (A) and a high signal intensity lesion (arrowhead) in left vastus lateralis muscle (B).
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