The Parkinson's lookalike whose damage hides in the brain's support cells
Multiple system atrophy can look like Parkinson's disease, with stiffness, slowness and tremor, but it usually barely responds to Parkinson's drugs. The reason lies deep in the tissue: its misfolded protein clumps collect mainly inside oligodendrocytes, the brain's insulating support cells, rather than in neurons.
Milton Shy and Glen Drager first described the disorder in 1960, which is why it is also called Shy-Drager syndrome. It is rare, begins typically between 50 and 60, and about 55% of patients are men. Neurons are progressively lost in the basal ganglia, cerebellum, pons, inferior olivary nucleus and spinal cord. Current criteria, revised in 2022, require failure of the automatic nervous system, such as a blood pressure drop of at least 20/10 within three minutes of standing or unexplained urinary urgency, plus a movement problem: either parkinsonism, the MSA-P form, or unsteady coordination, the MSA-C form.
The earliest sign in 62% of patients is slowness and rigidity resembling Parkinson's; balance trouble opens the story in 22%, and bladder symptoms in 9%. Around one in five fall within the first year. In men erectile dysfunction can come first, and vocal cord palsy is sometimes an early clue. Only about 9% of those with tremor show the classic pill-rolling movement of Parkinson's.
Like Parkinson's and the Lewy body dementias, MSA is a synucleinopathy, driven by misfolded alpha-synuclein that may spread like a prion. But its clumps, called Papp-Lantos bodies, sit in oligodendrocytes, which make little of the protein themselves and probably absorb it from neurons. The shape of the protein differs from the Lewy body version, and experiments suggest the oligodendrocyte strain drives more aggressive disease. A mouse study comparing the two subtypes found no difference between their protein aggregates, supporting the idea that one strain simply starts in different brain regions.
Diagnosis is hard. Scans may show a shrunken cerebellum and pons or a hot cross bun pattern, but are often normal early, and certainty comes only at autopsy. In 2020 a Houston team reported a protein amplification test that could separate MSA from Parkinson's objectively. A retrospective study of 158 patients linked tube feeding with a modest survival advantage, which its authors tied to wider respiratory care.
Source: Multiple system atrophy
