A Woman With Leg Numbness, Pain, Weakness, and Slow Nerve Conduction Velocities

A 41-year-old woman was referred by another neurologist because of leg pain with numbness and tingling in the feet for 4 years. In the last 2 years, she developed leg weakness and difficulty walking.

Her previous workup revealed EMG and nerve biopsy findings consistent with a demyelinating neuropathy with slow nerve conduction velocities. Spinal fluid protein was normal at 36 mg/dL. She had normal serum B ₁₂ , fasting blood sugar, glycosylated hemoglobin, immunoelectrophoresis, FANA, and thyroid function tests, and her HIV test was negative.

Past medical history was significant only for gallbladder surgery and appendectomy. Family history was negative.

The patient was infused with 2 g/kg of gamma globulin without benefit and was subsequently referred for evaluation.

Neurologic examination revealed normal mentation and cranial nerves. She had difficulty walking on heels or toes. Muscle strength in the upper extremities was normal except for 4/5 weakness in the hand interosseous muscles. In the lower extremities iliopsoas strength was 4+/5, glutei 4/5, quadriceps 5/5, tibialis anterior and peronei 4−/5, foot flexors and evertors 5/5, and toe extensors 4−/5. There was no evidence of muscle atrophy or fasciculations. Reflexes were absent throughout. Vibration sense was absent in the toes and ankles and diminished in the knees and fingers. Pinprick sensation was decreased up to the ankles. Two-point discrimination was abnormal in the fingers and toes. Position sense was decreased in the toes. Coordination was intact. There were no Babinski signs. She did not have visceromegaly, high arches ( Fig. 62A-1 ), hammertoes, or nerve hypertrophy. No Mees lines were seen. The rest of the examination was normal.

What is the Differential Diagnosis?

This patient had a polyneuropathy with a fairly recent onset of symptoms, a negative family history, lack of exposure to medications or toxins, and normal blood work for common causes of polyneuropathy.

She was previously diagnosed with a demyelinating polyneuropathy. The small nerve fiber involvement is not classical but can occur in those neuropathies. A presumptive diagnosis of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) was made initially, but she did not improve with IgG treatment. Other possibilities include a hereditary neuropathy, such as Charcot–Marie–Tooth (CMT) disease, although family history and stigmata were absent, she was not exposed to toxins and was not a diabetic.