Pathological basis and clinical significance of Gerhardt syndrome in multiple system atrophy

Abstract

Multiple system atrophy (MSA) is a progressive neurodegenerative disorder characterized by autonomic failure, parkinsonism, and cerebellar ataxia. Gerhardt syndrome denotes inspiratory dyspnea with laryngeal stridor caused by vocal fold dysfunction. It occurs frequently in patients with MSA and has been associated with nocturnal, potentially fatal upper-airway obstruction and sudden death. Two principal mechanisms have been proposed: (1) dystonic overactivity of the adductor muscles of the vocal folds; and (2) neurogenic atrophy or denervation of the posterior cricoarytenoid, the sole abductor of the vocal folds. Recent studies indicate that these abnormalities are not mutually exclusive and may coexist within the same patient. This mini-review summarizes current histopathological findings encompassing laryngeal muscle pathology and brainstem changes relevant to Gerhardt syndrome in MSA and outlines their clinical implications. By integrating recent evidence, we highlight how a coexistence model of adductor dystonia and abductor denervation refines our understanding of pathophysiology and may guide individualized management strategies in clinical practice.