A Man With Diabetic Polyneuropathy Who Developed Rapidly Progressive Weakness

A 53-year-old obese, insulin-dependent, hypertensive diabetic man presented initially with a diabetic polyneuropathy characterized by numbness and burning paresthesias in the feet. His examination at that time was remarkable only for absent ankle reflexes, absent vibration sense in the toes and ankles, and decreased pinprick to the mid-calf and wrists. His electrodiagnostic tests showed borderline slow peroneal motor conduction velocities, mildly prolonged median distal motor latency, and absent sural SNAPs and H-reflexes. Median and ulnar nerve conduction velocities, CMAPs, and SNAPs were normal. The needle EMG showed scattered large motor unit potentials in the distal legs. He was treated with ibuprofen and amitriptyline.

He presented 2 years later with a 5-week history of progressive weakness in the lower extremities causing significant difficulty walking; he also had mild weakness in the upper extremities. His numbness had progressed to the distal shins.

Past medical history included back surgery for disk disease and polycythemia secondary to fluoxymesterone, given for impotence; this was discontinued 4 years prior to this presentation. Later, he had a penile implant.

The patient stopped using alcohol and tobacco 2 years previously after a myocardial infarction and coronary bypass surgery. Family history was noncontributory. Review of systems revealed excessive daytime sleepiness, snoring, and some jerking movements in the legs at night.

Physical examination revealed normal mentation and cranial nerves. Upper extremity strength was 4+/5 in the shoulder muscles, biceps, and triceps, and 3+/5 in the finger extensors, flexors, and hand muscles. Lower extremity strength was 3−/5 in the hips and 4/5 in the quadriceps and hamstrings; foot extensors were 2/5; foot dorsiflexors and evertors were 4/5. He was areflexic throughout. He had decreased touch and pain sensations to the distal shins and wrists. Vibration sense was absent in the toes and ankles and decreased in the knees and fingers. Position sense was absent in the toes and decreased in the ankles. Romberg test was negative. Coordination was normal. There were no Babinski signs. The rest of the examination was normal.

What Tests were Done?

The chemistry profile was normal except for sugar of 249 mg/dL (normal, <110 mg/dL); he had normal serum immunoelectrophoresis, HIV, fluorescent antinuclear antibody test, erythrocyte sedimentation rate, B ₁₂ angiotensin-converting enzyme, and thyroid-stimulating hormone.

What is the Differential Diagnosis?

This diabetic man had rapidly progressive weakness, and although this could be related to diabetic polyneuropathy, it also included proximal muscles. A superimposed myopathy, such as polymyositis, is a consideration, but the areflexia, particularly of the proximal reflexes and the prominent proprioceptive sensory deficit, suggests the weakness was secondary to a neuropathy. The rapidly progressive weakness with proprioceptive deficit is also against a motor neuron disorder. He could have had hypothyroidism causing a neuropathy in addition to his diabetic neuropathy. B ₁₂ deficiency might present with numbness, some weakness, and areflexia, but there could also be evidence of long tract signs. Other possibilities include a subacute form of inflammatory demyelinating polyneuropathy, a vasculitic neuropathy, sarcoidosis, HIV- or monoclonal gammopathy–associated demyelinating neuropathy, and a neuropathy associated with lymphoma.

He also appeared to have had sleep apnea.