A Diabetic Man With Bilateral Arm Weakness

A 47-year-old left-handed diabetic man on oral antidiabetics developed pain in the right elbow down to the forearm. Two days later, he had numbness over the posterior aspect of the right forearm and in the first three digits of the right hand that became weak, and later he could not move his left wrist. He then developed weakness in both elbows and the shoulders. He also had numbness in both feet. He was seen by his local doctor, who performed a cervical spine MRI that was normal.

Past medical history was unremarkable. He did not drink alcohol or smoke and had not been exposed to drugs. Family history was noncontributory.

General physical examination, mentation, and cranial nerves were normal. There was wasting and weakness in both trapezii and right deltoids and biceps, with weakness of the triceps and intrinsic muscles bilaterally, more on the left than on the right with severe weakness of the wrist extensors/flexors worse on the left ( Fig. 59-1 ). He had winging of the scapula more prominent on the right than on the left. Hand muscles were also weak. There were no fasciculations or myotonia. Strength in the lower extremities was normal. There was only a mild glove and stocking sensory deficit to all modalities to the midforearm and midleg. This was out of proportion to the weakness. There were no Babinski signs, and coordination and gait were normal.

What is the Differential Diagnosis?

This patient’s presentation of proximal and distal weakness of the arms could suggest a motor neuron disorder, but the sensory deficits, pain, and abrupt onset are against this diagnosis. Cervical spine diseases like spondylosis, ruptured disk, or tumor are a good possibility, but the previous normal MRI is against these. A bilateral brachial plexopathy is another consideration.

Due to the step-wise accumulation of deficits, he appeared to have a mononeuritis multiplex involving the upper extremities. This could be secondary to diabetes or a systemic vasculitis associated with a connective tissue disorder, or he could have nonsystemic vasculitis of the peripheral nerves. Other considerations are Lyme disease and HIV.

What Needs to Be Done?

Erythrocyte sedimentation rate and a complete metabolic panel were normal, except for an elevated glucose of 242 mg/dL (normal, <110 mg/dL) and glycosylated hemoglobin of 8% (normal, <6%). Immunoelectrophoresis, fluorescent antinuclear antibody, antineutrophil cytoplasmic antibody, cryoglobulins, hepatitis profile, angiotensin-converting enzyme, Lyme serology, and HIV tests were all negative. Chest x-ray was normal.