脱力、不整脈。心臓に異常な蓄積物が生じることに因る。
運動後に目眩と動悸を訴えた。心室細動を認め入院。除細動。
a 27-year-old man who had muscle weakness associated with the depletion of glycogen in skeletal muscle and cardiac arrhythmias associated with the accumulation of abnormal storage material in the heart. He presented with dizziness and palpitations after exercising, and was found to be in ventricular fibrillation that was cardioverted to normal sinus rhythm; during his hospitalization, he continued to have episodic ventricular tachycardia, and underwent placement of an implantable cardioverter-defibrillator (ICD). In childhood, he had always been slightly weak in the upper arms, and ran more slowly than peers due to shortness of breath. He had no sensory or cognitive symptoms, and there were no episodes of suspected myoglobinuria. At age 19, he was dismissed from military service due to reduced muscle mass and an abnormal electrocardiogram (ECG), with T-wave inversions in inferior leads and ST-segment elevations in V2 and V3; an echocardiogram was reportedly normal. Neurologic examination at 27 years of age revealed slight weakness in neck flexion, shoulder abduction, elbow flexion and extension, the abdominal muscles, and foot dorsiflexion, as well as slight scapular winging. Hip and thigh strength were normal. ECG showed incomplete right bundle branch block and inferior T-wave inversion. Echocardiogram revealed slightly increased posterior wall thickness and a normal ejection fraction. Nerve conduction velocities were normal, but needle electromyography showed slight myopathic changes. The patient's 3 older brothers and mother had no symptoms of neuromuscular impairment, but his father, paternal grandfather, and paternal grandfather's sister all had distal axonal neuropathy due to Charcot-Marie-Tooth disease type 2 (see 118210). Skeletal muscle biopsy in the patient showed a profound deficit of glycogen, with marked predominance of slow-twitch, oxidative muscle fibers and mitochondrial proliferation. Endomyocardial biopsy showed hypertrophic cardiomyocytes with enlarged nuclei and large centrally located vacuoles containing periodic acid Schiff (PAS)-positive material that was ultrastructurally different from glycogen. The remainder of the cytoplasm showed glycogen depletion.
