Autonomic dysfunction in multiple system atrophy: from pathophysiology to clinical manifestations

Multiple system atrophy (MSA) is a sporadic, fatal, and rapidly progressive neurodegenerative disease of unknown etiology, pathologically characterized by the presence of α-synuclein (α-syn) immunoreactive cytoplasmic inclusions in oligodendrocytes. The deposition of α-synuclein in highly interconnected neuronal networks with different neurochemistry properties in different regions of the cortex, diencephalon, brain stem and spinal cord leads to early onset and extensive autonomic dysfunction in MSA. Mainly affected areas include the hypothalamus, pons, raphe nucleus, locus coeruleus, arcuate nucleus, dorsal vagus nucleus, fuzzy nucleus, the thoracolumbar middle lateral column and Onuf's nucleus of the spinal cord. Clinical manifestations include orthostatic hypotension, incomplete bladder emptying, erectile dysfunction, and constipation.

In this review, we aim to discuss and summarize the clinicopathological correlation of MSA autonomic dysfunction, and focus on the pathophysiological mechanisms of various autonomic dysfunction, from neural control networks under normal physiological conditions to specific pathological involvement structures in MSA. In addition, we also elaborated on the corresponding clinical manifestations caused by various pathological structures.

In summary, the autonomic dysfunction of MSA involves the comprehensive control of cardiovascular, urinary, reproductive, and gastrointestinal functions by the autonomic nervous network in the central nervous system (CNS). The currently summarized physiology and pathophysiology of MSA have not been fully clarified. Further and deeper studies are needed to elucidate the relationship between pathogenesis and clinical manifestations of MSA.