Leg weakness is most commonly a presentation of neuromuscular and orthopedic etiology.  Identification of the underlying pathology is essential is guiding treatment and prognosis.  Electrodiagnostic and imaging studies are essential.  Rarely, the clinical presentation and diagnostics may require us to consider medical etiology of the weakness.

Case report from a tertiary medical center.

A 48 year-old woman with history of sciatica presented right foot numbness/ tingling and leg weakness.  The symptoms started after she used a knee high cast for lateral malleolus fracture.  The left leg and the arms were unaffected.  On exam, right plantarflexion, EDB and inversion were 1/5.  There was right calf muscle atrophy and sensory loss in the posterior lateral leg and foot. Reflexes were normal and symmetric, plantar responses were flexor.  NCS/EMG demonstrated chronic neuropathic involvement of the tibial portion of the right sciatic nerve.  MRI of the lumbar spine showed small disk bulge at L5-S1.  MRI of the pelvis and the lower extremity showed enlargement and enhancement of the right sciatic nerve and osseous lesion in the inferolateral aspect of the femoral neck.  Sciatic nerve and femoral neck biopsy showed metastatic neuroendocrine tumor.  CT of the chest, abdomen and pelvis showed multiple pulmonary nodules.  PET scan confirmed hypermetabolic mass in the right sciatic nerve, femoral neck and bilateral pulmonary nodules.  Lung biopsy confirmed primary lung cancer.  The patient was treated with octreotide for metastatic neuroendocrine carcinoma and radiation to the right femur.  The lung lesions progressed and after unsuccessful trial of everolimus the patient was enrolled in a research study.