A Diabetic Man With Back and Leg Pain

A 60-year-old, type 2 diabetic man woke up 2 months prior to admission with back pain that radiated to the left leg below the knee, particularly in the inner side of the leg. It was a nonspecific ache, not a shooting pain. This worsened when having bowel movements. He was more uncomfortable when he sat or stretched out his legs to sleep at night. He took nonsteroidal antiinflammatories without relief.

Past medical history was unremarkable. His diabetes was controlled with oral agents. Family history was noncontributory. He did not smoke, drink, or use recreational drugs.

General physical examination was essentially unremarkable. Neurologic examination showed normal mentation, cranial nerves, and muscle strength; reflexes were 2+ in the upper extremities and the right knee, the left knee reflex was absent, and they were trace at both ankles. There were no pathologic reflexes. Sensory examination showed diminished vibration and touch sensations in the toes and normal pinprick sensation throughout, except for the left anterior thigh. Straight leg raising and femoral stretch were negative. Coordination was normal.

What is the Differential Diagnosis?

This diabetic patient presented with pain in the back and leg, decreased sensation in the anterior left thigh, and an absent knee jerk, which are highly suggestive of an L3–L4 root disease. A mild femoral neuropathy or lumbosacral plexopathy could not be ruled out clinically.

The increased pain with effort might suggest a root compression, and clinically the patient also had signs of a peripheral neuropathy.

Various etiologies should be considered for his presentation, including a ruptured disk, facet hypertrophy, spinal or plexus tumor, and diabetic lumbosacral radiculoplexopathy. However, the back pain and lack of significant weakness are against this diagnosis.

What Diagnostic Tests should be Done?

His fasting blood sugar was 180 mg/dL (normal, 65–120 mg/dL) and his glycosylated hemoglobin was 6.2% (normal, 5%–9%). Erythrocyte sedimentation rate, chemistry profile, and thyroid-stimulating hormone levels were normal.