The etiology is suspected to be a vasculitic. NCS should include sensory studies of the saphenous nerve and motor studies of the femoral nerve. When evaluating femoral nerve conduction studies comparison to the asymptomatic side should be completed. On EMG, the quadriceps should show neuropathic changes. The adductor magnus and brevis, which share lumbar innervation with quadriceps and iliopsoas will be spared since they are innervated primarily by the obturator and sciatic nerves.
Treatment is dependent on the etiology of the lesion.
Most patients with a femoral mononeuropathy can be treated conservatively with physical therapy, avoidance of excessive hip abduction and external rotation and knee bracing to prevent buckling of the knee. In patients with femoral neuropathy associated with positional compression or retraction compression during surgery or delivery, recovery typically occurs over 3-4 months. When the cause of the neuropathy is a retroperitoneal hematoma, evacuation of the hematoma may be indicated but is controversial. In patients on anticoagulation therapy, stopping anticoagulation is required until the hematoma has resolved. Their outcome is worse than those with a hematoma due to trauma.