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The case of the vanishing vim

Diagnostic Challenge

Kirk Hollohan, MD

St. Paul’s Hospital, Vancouver, BC

CJEM 1999;1(3):164

A 39-year-old Asian male presented to the ED complaining of weakness that began gradually after eating a large meal. His legs were affected more than his arms and, over 3 to 4 hours, the weakness progressed to the point that he could no longer bear weight. He also noted palpitations and tingling in both legs, but there was no headache, dizziness, diplopia, dysphagia, dysarthria or shortness of breath. On further questioning, he reported a tremor, heat intolerance, diaphoresis and palpitations, and a loss of 20 pounds over a 2-month period.

The patient denied previous attacks of weakness, but remembered a similar episode of weight loss and heat intolerance 15 years earlier while he was living in China. This episode resolved after treatment with an unknown medicine. His current medications included some Chinese preparations (which he did not bring to the ED). He did not smoke, nor drink alcohol, and he denied illicit drug use.

On exam, he was alert, oriented and anxious but in no distress. Heart rate was 92 beats/min and irregular. Blood pressure was 112/60 mm Hg, respiratory rate 24 breaths/min, and temperature 35.3ºC. Physical findings included lid lag, exopthalmos, and a nontender, enlarged (15 cm) nodular thyroid gland with audible bruit. Cranial nerves were normal, and upper extremity strength was 4/5 bilaterally. Lower extremity strength was 2/5 proximally and 3/5 distally. Muscle bulk was normal and no tenderness was noted, but tone was decreased in all 4 limbs. Reflexes were 1+ in the upper limbs and absent in the lower limbs. Touch, pin and position sense was normal in all 4 limbs, and the rest of the physical examination was unremarkable. The ECG revealed atrial fibrillation at 92 beats/min. The most likely diagnosis is

  1. myasthenia gravis related to thyrotoxicosis
  2. Guillian–Barré syndrome complicated by thyrotoxicosis
  3. myopathic weakness secondary to hyperthyroidism
  4. thyrotoxic periodic paralysis

For the Answer to this Challenge, see page 192.

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