Spinal and bulbar muscular atrophy with pseudomyotonia phenomena: a clinical case report

Abstract

A clinical description of a 28-year-old man with spinal and bulbar muscular atrophy diagnosed on the basis of the CAG-trinucleotide expansion in the gene coding androgen receptor is presented. He exhibited skeletal muscles and tongue fasciculations, gynecomastia, increased serum testosterone and creatine kinase levels. The peculiarities of the case were the gynecomastia under the age of 7, development of fasciculations at the age of 11 and appearance of hard muscle stiffness with delayed muscle relaxation after voluntary contraction at the age of 15, which resembled typical myotonia. Electromyography showed few signs of mild without myotonic discharge, contrasting with giant motor unit potentials and reduced recruitment. The cause of myotonia-like symptom without myotonic discharge as a feature of skeletal muscles disorder is discussed with the modern view of spinal and bulbar muscular atrophy as a multisystem genetic pathology.