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Abstract
Background and Objectives To assess the clinical and electrophysiologic features of female carriers and early-stage male patients with spinal and bulbar muscular atrophy (SBMA) to elucidate the early pathophysiologic changes of the disease.
Methods Female carriers, early-stage male patients with SBMA, and age-matched male and female healthy controls were recruited. The results of motor functional scales, motor unit number estimation, dual-energy X-ray absorptiometry, and peripheral blood tests were compared between female carriers and healthy female controls and between patients with SBMA and healthy male controls. EMG was also investigated in female carriers.
Results We enrolled 21 female carriers and 11 early-stage male patients. Seventeen female and 14 male age-matched healthy controls were also enrolled. Female carriers experienced early-stage symptoms such as muscle cramps more frequently than healthy female controls. Decreased motor unit number estimation and EMG abnormalities including high amplitude or polyphasic potentials were observed in female carriers together with mild muscle weakness in neck flexion and a slow walking speed. Changes of muscle-related markers, including serum creatine kinase and dual-energy X-ray absorptiometry, were clearly detected in early-stage male patients with SBMA, but not in female carriers.
Discussion The present study revealed that female carriers of SBMA manifest mild muscular weakness associated with changes in neurogenic biomarkers. Conversely, male patients showed neurogenic and myopathic changes even at the early stage. These results suggest a testosterone-independent neurodegenerative pathophysiology in female SBMA carriers.
Glossary
- ALSFRS-R=
- revised Amyotrophic Lateral Sclerosis Functional Rating Scale;
- ALST=
- appendicular lean soft tissue;
- AR=
- androgen receptor;
- CK=
- creatine kinase;
- CMAP=
- compound muscle action potential;
- MMT=
- Manual Muscle Test;
- mQMG=
- modified Quantitative Myasthenia Gravis;
- MUNE=
- motor unit number estimation;
- NfL=
- neurofilament light chain;
- SBMA=
- spinal and bulbar muscle atrophy;
- SBMAFRS=
- SBMA Functional Rating Scale;
- SMUP=
- single motor unit potential
Footnotes
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
Submitted and externally peer reviewed. The handling editor was Anthony Amato, MD, FAAN.
- Received June 5, 2022.
- Accepted in final form August 17, 2022.
- © 2022 American Academy of Neurology
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