Hypoparathyroidism: A rare mimic of amyotrophic lateral sclerosis

Introduction: Amyotrophic lateral sclerosis (ALS) carries a grim prognosis. Various ALS mimics have been reported and should be excluded before confirming this diagnosis. Methods: We report the case of a 61-year-old man who presented with progressively worsening limb weakness and dysphagia. His examination showed mixed upper and lower motor neuron signs without sensory impairment. ALS was suspected, however, atypical diffuse pain prompted diagnostic work-up to exclude other causes. Results: Electrodiagnostic testing was suggestive of a sensorimotor polyneuropathy with superimposed diffuse active denervation suspicious for anterior horn cell degeneration. Brain MRI showed bilateral basal ganglia and thalamic calcifications. Laboratory studies confirmed the diagnosis of hypoparathyroidism. Treatment with calcium and vitamin D resulted in significant improvement at 6 months follow-up. Conclusions: Hypoparathyroidism, a treatable endocrinopathy, can rarely present clinically as ALS. In atypical cases, this should be ruled out before making a final diagnosis. Muscle Nerve, 2016 Muscle Nerve 55: 437–439, 2017.