Clinical Reasoning: A 48-year-old woman with generalized weakness

Abstract

A 48-year-old woman was referred to the neuromuscular clinic because of progressive generalized weakness for 4 months. Her symptoms started after she had a thyroidectomy and radioactive iodine treatment for a thyroid papillary carcinoma. She had proximal arm weakness when washing her hair and had trouble climbing steps and getting out of her chair without using her arms. About 2 months later, she developed fluctuating bilateral ptosis and blurred vision. Her symptoms were associated with episodes of transient horizontal binocular diplopia that would last for a couple of minutes and get worse by the end of the day. She also had dry eyes and mouth. A month later, she started having episodes of transient dysarthria. At that time she was found to have a low am cortisol level by the medical team while being evaluated for her symptoms. She was treated with a hydrocortisone taper which partially improved her weakness and a follow-up cortisol level suggested resolution of the adrenal insufficiency. The patient was on levothyroxine with normal thyroid gland function. She smoked 1 or 2 cigarettes daily for 10 years. She denied head drop, shortness of breath, lightheadedness, constipation, or weight loss. Her general examination, including orthostatic blood pressure, was normal. Her mental status was normal; visual acuity could be corrected to 20/20. Her pupils were symmetric with a sluggish response to light. Extraocular movements were intact and there was no ocular misalignment on alternate cover testing. There was no lid-twitch. She had mild right ptosis that worsened with sustained upgaze. Facial sensation was intact. There was no facial weakness, dysarthria, or dysphagia. The palate was midline and elevated symmetrically. The tongue movements were normal. No fasciculations were observed. Her strength was 4/5 in both biceps and psoas, which improved on repeated testing. The remaining neurologic examination, including deep …