Spinal and bulbar muscular atrophy (SBMA) is an X-linked neuromuscular disorder primarily affecting adult males due to the expansion of CAG repeats in the androgen receptor gene. It manifests as progressive lower motor neuropathy and androgen deficiency. A Japanese man in his late 50s presented with gradually progressive muscle weakness over 6 years. Examination revealed muscle weakness and atrophy in upper and lower limbs, decreased deep tendon reflexes, involuntary facial movements, bilateral finger tremors, tongue atrophy, fasciculations and bilateral gynaecomastia. Blood tests indicated elevated creatine kinase and mild hepatic dysfunction. Nerve conduction studies showed decreased sensory nerve action potentials, and electromyography demonstrated neurogenic changes. Genetic testing confirmed SBMA with 47 CAG repeats despite no family history. Treatment included leuprorelin acetate and rehabilitation using a wearable cyborg hybrid-assistive limb. As SBMA progresses slowly and symptoms like hand tremors and decreased serum creatinine precede significant weakness, early recognition is critical for diagnosis.
Suzuki et al. (Fri,) studied this question.