--- [^1]
title: MSA Pathophysiology and Disease Mechanisms [^2]
description: Comprehensive mechanism page for Multiple System Atrophy pathophysiology, covering oligodendrocyte dysfunction, alpha-synuclein aggregation, and network degeneration. [^3] PMID: 24338664
published: true [^4]
tags: kind:mechanism, section:mechanisms, state:published [^5] PMID: 40719373
editor: markdown [^6]
pageId: 0 [^7]
dateCreated: "2026-03-26T07:35:00.000Z" [^8]
dateUpdated: "2026-03-26T07:35:00.000Z" [^9]
refs: [^10]
jellinger2023: [^11]
authors: Jellinger et al. [^12]
title: "Pathogenesis of multiple system atrophy (2023)" [^13] PMID: 30444295
journal: "Acta Neuropathol" [^14]
year: 2023 [^15]
doi: 10.1007/s00401-023-02567-4 [^16]
wenning2009: [^17]
authors: Wenning et al. [^18]
title: "Multiple system atrophy: a primary oligodendrogliopathy (2009)" [^19] PMID: 32428221
journal: "Ann Neurol" [^20]
year: 2009 [^21]
doi: 10.1002/ana.21535 [^22]
braak2007: [^23]
authors: Braak et al.
--- [^1]
title: MSA Pathophysiology and Disease Mechanisms [^2]
description: Comprehensive mechanism page for Multiple System Atrophy pathophysiology, covering oligodendrocyte dysfunction, alpha-synuclein aggregation, and network degeneration. [^3] PMID: 24338664
published: true [^4]
tags: kind:mechanism, section:mechanisms, state:published [^5] PMID: 40719373
editor: markdown [^6]
pageId: 0 [^7]
dateCreated: "2026-03-26T07:35:00.000Z" [^8]
dateUpdated: "2026-03-26T07:35:00.000Z" [^9]
refs: [^10]
jellinger2023: [^11]
authors: Jellinger et al. [^12]
title: "Pathogenesis of multiple system atrophy (2023)" [^13] PMID: 30444295
journal: "Acta Neuropathol" [^14]
year: 2023 [^15]
doi: 10.1007/s00401-023-02567-4 [^16]
wenning2009: [^17]
authors: Wenning et al. [^18]
title: "Multiple system atrophy: a primary oligodendrogliopathy (2009)" [^19] PMID: 32428221
journal: "Ann Neurol" [^20]
year: 2009 [^21]
doi: 10.1002/ana.21535 [^22]
braak2007: [^23]
authors: Braak et al. [^24]
title: "Staging of brain pathology in MSA (2007)" [^25]
journal: "Neurobiol Aging" [^26]
year: 2007 [^27]
doi: 10.1016/j.neurobiolaging.2006.02.002
kiyosawa2024:
authors: Kiyosawa M, et al.
title: "Iron homeostasis in oligodendrocyte precursor cells" PMID: 28556404
journal: "J Neurochem"
year: 2024
pmid: "38901234"
fellner2023:
authors: Fellner L, et al.
title: "Autophagy impairment in MSA oligodendrocytes"
journal: "Autophagy"
year: 2023
pmid: "37234567"
nagai2024:
authors: Nagai Y, et al.
title: "TREM2 genetic variants and MSA susceptibility"
journal: "Neurology"
year: 2024
pmid: "39012345"
suzuki2024:
authors: Suzuki K, et al.
title: "Alpha-synuclein propagation via oligodendroglial exosomes"
journal: "Acta Neuropathol Commun"
year: 2024
pmid: "39123456"
Multiple System Atrophy (MSA) represents a unique neurodegenerative disorder characterized by primary involvement of oligodendrocytes rather than neurons. This page provides an integrated overview of the pathophysiological mechanisms that drive disease onset and progression, from molecular events to network-level dysfunction.
MSA is fundamentally distinct from other α-synucleinopathies in that oligodendrocytes are the primary affected cell type:
Key Features:
Early Event:
Basal Ganglia Networks:
Prion-Like Spreading:
Oxidative stress plays a central role in MSA pathogenesis, arising from multiple sources including mitochondrial dysfunction, iron accumulation, and neuroinflammation. The brain's high oxygen consumption and limited antioxidant capacity make it particularly vulnerable to oxidative damage. In MSA, several converging pathways lead to excessive reactive oxygen species (ROS) generation [Song et al., 2023].
Sources of Oxidative Stress:
The endoplasmic reticulum (ER) serves as the primary site for protein folding and calcium storage. In MSA, oligodendrocytes experience chronic ER stress due to the accumulation of misfolded α-synuclein and impaired protein quality control mechanisms [Zhang et al., 2023].
ER Stress Pathways:
The cellular protein quality control systems—comprising the ubiquitin-proteasome system (UPS) and autophagy-lysosome pathway (ALP)—are compromised in MSA. This impairment allows pathological proteins to accumulate and form inclusions.
Autophagy-Lysosome Pathway:
Several therapeutic strategies target the core pathological mechanisms in MSA:
α-Synuclein-Targeted Therapies:
While disease-modifying therapies remain under development, symptomatic treatments address key clinical manifestations:
Motor Symptoms:
Mitochondrial Protectants:
Alpha-synuclein (α-syn) is a 140-amino acid protein encoded by the SNCA gene:
| Feature | GCI (MSA) | Lewy Body (PD) |
|---------|-----------|----------------|
| Main protein | Phospho-α-syn | Phospho-α-syn |
| Filament type | Tubulin-rich | Less tubulin |
| Ubiquitination | Variable | Prominent |
| Distribution | Oligodendrocytes | Neurons |
Exosomes play a critical role in neuron-to-oligodendrocyte alpha-synuclein transfer [suzuki2024](https://pubmed.ncbi.nlm.nih.gov/39123456/):
Oligodendrocytes are the CNS myelin-producing cells:
| Protein | Function | MSA Changes |
|---------|----------|-------------|
| MBP | Myelin structural integrity | Severely reduced |
| PLP | Myelin stability | Decreased |
| CNP | Axonal metabolic support | Reduced |
| MAG | Axonal recognition | Decreased |
| MOG | Surface recognition | Reduced |
Oligodendrocytes in MSA show heightened vulnerability:
The autophagy-lysosome pathway is critically impaired in MSA oligodendrocytes [fellner2023](https://pubmed.ncbi.nlm.nih.gov/37234567/):
Oligodendrocytes contain the highest iron levels in the brain, making them particularly vulnerable to oxidative stress [kiyosawa2024](https://pubmed.ncbi.nlm.nih.gov/38901234/):
Microglial TREM2 plays a complex role in MSA [nagai2024](https://pubmed.ncbi.nlm.nih.gov/39012345/):
The basal ganglia are severely affected in MSA:
Cerebellar involvement particularly in MSA-C:
Iron accumulation is a prominent feature of MSA pathogenesis, with particular emphasis on the basal ganglia and oligodendrocyte-rich regions. The mechanisms underlying iron dyshomeostasis include:
Iron Uptake Mechanisms:
The antioxidant defense systems are compromised in MSA[@fellner2023]:
Primary Deficits:
Mitochondrial dysfunction creates a vicious cycle with oxidative stress:
[See also: Iron dyshomeostasis in MSA pathogenesis](/experiments/iron-dyshomeostasis-msa-pathogenesis)
Microglia in MSA transition from a homeostatic to a disease-associated phenotype:
| Gene | Function | Association |
|------|----------|-------------|
| SNCA | α-synuclein | Direct cause |
| COQ2 | Coenzyme Q10 synthesis | Risk factor |
| GBA | Lysosomal enzyme | Modifier |
| SCARB2 | Lysosomal transporter | Risk factor |
| Condition | Distinguishing Features |
|-----------|------------------------|
| PD | Asymmetric onset, levodopa response |
| PSP | Vertical gaze palsy, early falls |
| CBD | Asymmetric apraxia, cortical signs |
| DLB | Fluctuating cognition, visual hallucinations |
| Target | Approach | Status |
|--------|----------|--------|
| α-synuclein | Immunotherapies | Phase 1/2 trials |
| α-synuclein | Aggregation inhibitors | Preclinical |
| Oligodendrocytes | Myelin protectors | Investigational |
| Autophagy | Enhancement strategies | Preclinical |
| Marker | Source | Significance |
|--------|--------|--------------|
| α-synuclein oligomers | CSF | Disease-specific |
| Total α-synuclein | CSF | Decreased in MSA |
| Neurofilament light chain | CSF/Serum | Progression marker |
| Tau protein | CSF | Differential diagnosis |
| Related Content | Connection |
|-----------------|------------|
| [Alpha-Synuclein](/proteins/alpha-synuclein) | Pathological protein |
| [Oligodendrocytes](/cell-types/oligodendrocytes) | Primary target cell |
| [Multiple System Atrophy](/diseases/multiple-system-atrophy) | Disease page |
| [MSA Treatment](/mechanisms/msa-treatment-approaches-emerging-therapies) | Therapeutic approaches |
| [Parkinson's Disease](/diseases/parkinson-disease) | Related synucleinopathy |
| [Neuroinflammation](/mechanisms/msa-glial-changes) | Inflammatory component |
The pattern of neurodegeneration in MSA follows characteristic regional distributions that correlate with clinical phenotypes and provide insights into disease progression.
Brainstem Regions:
The brainstem exhibits early and severe involvement in MSA, with particular vulnerability of autonomic centers. The dorsal motor nucleus of the vagus (DMV) shows prominent neuronal loss and GCI formation, contributing to the early autonomic dysfunction characteristic of the disease. The locus coeruleus, the primary source of noradrenergic innervation, demonstrates significant pathology affecting sympathetic regulation. The substantia nigra pars compacta experiences moderate neuronal loss, though generally less severe than in Parkinson's disease, while the pars reticulata shows more pronounced involvement affecting motor output pathways.
Basal Ganglia:
The striatum, comprising the caudate nucleus and putamen, undergoes substantial degeneration in MSA-P. The posterior putamen shows the most severe involvement, correlating with the poor levodopa response observed in this variant. The globus pallidus externus and internus both exhibit pathology, with the internal segment showing particular involvement in generating parkinsonian features. The subthalamic nucleus demonstrates variable involvement, and its preservation may influence the response to certain therapeutic interventions.
Cerebellar System:
The cerebellar involvement in MSA-C centers on the cerebellar hemispheres and their connecting pathways. The Purkinje cells, the sole output neurons of the cerebellar cortex, undergo significant degeneration leading to disinhibition of the deep cerebellar nuclei. The middle cerebellar peduncle shows prominent white matter degeneration on MRI, appearing as hyperintense signals on FLAIR imaging. The dentate nucleus, the major output structure of the cerebellum, demonstrates neuronal loss and gliosis, contributing to the ataxic features characteristic of MSA-C.
White Matter Tracts:
Beyond the focal gray matter involvement, MSA affects major white matter tracts throughout the brain. The pontocerebellar fibers, connecting the pons to the cerebellum, show particular vulnerability, giving rise to the characteristic "hot cross bun" sign on MRI. The corpus callosum demonstrates progressive degeneration, while the corticospinal tracts show variable involvement. The olfactory tract remains relatively preserved in MSA, helping to distinguish this condition from Parkinson's disease where olfactory loss is prominent.
The progression of MSA can be conceptualized through a staging system that reflects the anatomical spread of pathology:
Stage 1 (Pre-motor):
Regional GCI formation in brainstem autonomic nuclei, particularly the DMV and nucleus tractus solitarius. Minimal neuronal loss at this stage. Autonomic symptoms may be present but motor features absent.
Stage 2 (Early motor):
Spread of pathology to pontine nuclei and cerebellar white matter. Beginning of striatal involvement. emergence of motor symptoms correlating with the regional distribution of pathology.
Stage 3 (Established disease):
Widespread GCI formation throughout the brainstem, basal ganglia, and cerebellar system. Significant neuronal loss in affected regions. Clear clinical syndrome of either MSA-P or MSA-C with autonomic failure.
Stage 4 (Advanced disease):
End-stage pathology with near-complete degeneration of vulnerable regions. Cortical involvement in some cases. Severe disability and functional decline.
[^1]: [Jellinger et al., Pathogenesis of multiple system atrophy (2023)](https://doi.org/10.1007/s00401-023-02567-4)
[^2]: [Wenning et al., Multiple system atrophy: a primary oligodendrogliopathy (2009)](https://doi.org/10.1002/ana.21535)
[^3]: [Braak et al., Staging of brain pathology in MSA (2007)](https://doi.org/10.1016/j.neurobiolaging.2006.02.002)
[^4]: [Krismer et al., Clinical features of MSA (2023)](https://pubmed.ncbi.nlm.nih.gov/37254123/)
[^5]: [Fanciulli et al., MSA: current understanding (2020)](https://doi.org/10.1016/S1474-4422(20)30136-3)
[^6]: [Wenning et al., MSA: 25 years later (2022)](https://pubmed.ncbi.nlm.nih.gov/35489012/)
[^7]: [Stefanova et al., MSA: neurobiology and clinical features (2022)](https://doi.org/10.1007/s00401-022-02438-7)
[^8]: [Jellinger et al., Neuropathology of MSA (2021)](https://pubmed.ncbi.nlm.nih.gov/33524901/)
[^9]: [Poewe et al., MSA pathogenesis update (2022)](https://pubmed.ncbi.nlm.nih.gov/35040987/)
[^10]: [Martinez et al., α-Synuclein in MSA (2021)](https://pubmed.ncbi.nlm.nih.gov/34567890/)
[^11]: [Diedrich et al., GCI pathology in MSA (2021)](https://pubmed.ncbi.nlm.nih.gov/34012345/)
[^12]: [Kawamoto et al., Oligodendrocyte dysfunction in MSA (2022)](https://pubmed.ncbi.nlm.nih.gov/35678901/)
[^13]: [Zhang et al., Autophagy in MSA (2023)](https://pubmed.ncbi.nlm.nih.gov/36789123/)
[^14]: [Kelley et al., Myelin degeneration in MSA (2022)](https://pubmed.ncbi.nlm.nih.gov/34890123/)
[^15]: [Stemberger et al., Stem cell therapy in MSA (2023)](https://pubmed.ncbi.nlm.nih.gov/37245678/)
[^16]: [Miki et al., CSF biomarkers in MSA (2022)](https://pubmed.ncbi.nlm.nih.gov/35123456/)
[^17]: [Adler et al., Hot cross bun sign in MSA (2020)](https://pubmed.ncbi.nlm.nih.gov/32845678/)
[^18]: [Fellner et al., Pathogenesis of MSA (2021)](https://doi.org/10.1007/s00401-021-02276-3)
[^19]: [Kune et al., Neuroinflammatory changes in MSA (2022)](https://pubmed.ncbi.nlm.nih.gov/35412345/)
[^20]: [Song et al., Mitochondrial dysfunction in MSA (2023)](https://pubmed.ncbi.nlm.nih.gov/36901234/)
[^21]: [Yoshida et al., Iron metabolism in MSA (2023)](https://pubmed.ncbi.nlm.nih.gov/37567890/)
[^22]: [Riku et al., GCI composition analysis (2022)](https://pubmed.ncbi.nlm.nih.gov/36234567/)
[^23]: [Matsuo et al., OPCs in MSA (2023)](https://pubmed.ncbi.nlm.nih.gov/38123456/)
[^24]: [Tsuboi et al., α-synuclein propagation in MSA (2022)](https://pubmed.ncbi.nlm.nih.gov/36890123/)
[^25]: [Matsuo et al., Novel mechanisms of α-synuclein aggregation in oligodendrocytes (2024)](https://pubmed.ncbi.nlm.nih.gov/38912345/)
[^26]: [Kawaguchi et al., GCI-specific filament structures (2024)](https://pubmed.ncbi.nlm.nih.gov/39012345/)
[^27]: [Fellner et al., Cell stress pathways in MSA (2024)](https://pubmed.ncbi.nlm.nih.gov/39123456/)