A case of late-onset proximal and distal muscle weakness

Abstract

At initial presentation, our patient was a 49-year-old woman with 3 years of progressive weakness. She noted difficulty standing up straight and climbing stairs. Over the next 2 years, she had “winging” of her shoulder blades and difficulty lifting her arms over her head. She denied fatigue, fasciculations, myalgias, cramps or stiffness, ptosis, double vision, difficulty chewing or swallowing, dysarthria, dyspnea, sensory symptoms, incontinence, rash, arthralgias, and bone pain. The patient’s mother developed difficulty walking in her late 50s, with “flapping of her feet,” winging of the scapulae, dysphagia, and dysarthria. A maternal uncle also used a wheelchair in mid-adult life, and the patient’s maternal grandmother was diagnosed with Roussy-Levy syndrome. The patient has one 48-year-old brother and 6 adult children without medical problems. Her family history and medical history were otherwise unremarkable. She was taking no medications. General examination was unremarkable. Mental status was normal. Cranial nerves were intact. Motor examination revealed bilateral scapular winging and paraspinal muscle atrophy. No fasciculations, myotonia, or paramyotonia were appreciated. Manual muscle testing demonstrated Medical Research Council (MRC) grades of 4 proximally and 4+ distally in the arms and legs. Sensation and muscle stretch reflexes were intact. Plantar responses were flexor. The patient had a hyperlordotic, wide-based, and waddling gait. The patient’s weakness progressed over the next several years. At the age of 54 years, she had the following MRC scores: neck flexion 5−, neck extension 5−, shoulder abduction 3−, elbow flexion 4 on the right and 2 on the left, elbow extension 5, wrist extension 4+ on the right and 4 on the left, wrist flexion 5, finger extension 4+, and finger flexors 5. In the lower extremities, she had hip flexion, abduction, and extension 2, knee extension 3−, ankle dorsiflexion and plantar flexion 1 on right and 4− on left. Workup …