Multiple System Atrophy typically presents in 50-60 year old adults with autonomic dysfunction, parkinsonian features, and cerebellar ataxia. Pathologically, hallmark features include glial cytoplasmic inclusions and degeneration of multiple brain regions, while radiologically, it is characterised by atrophy of the putamen, cerebellum, and brainstem, with the “hot cross bun” sign on MRI.
Description
Multiple System Atrophy (MSA) is a progressive neurodegenerative disorder characterized by a combination of autonomic failure, parkinsonism, and ataxia. It is classified into two primary types based on the predominant symptoms: MSA-P, where parkinsonian features prevail, and MSA-C, with cerebellar ataxia as the main feature.
Pathogenesis
The exact cause of MSA is unknown, but the disease is characterised by the accumulation of alpha-synuclein protein within glial cells, leading to glial cytoplasmic inclusions. This pathological process results in the degeneration of multiple parts of the brain, including the basal ganglia, cerebellum, and brainstem.
Subtypes
- MSA-P (Parkinsonian type): More common, characterised by bradykinesia, rigidity, and tremors.
- MSA-C (Cerebellar type): Features cerebellar ataxia, unsteady gait, and impaired coordination.
Epidemiology, Risk Factors & Associations
- Typically affects individuals aged 50-60 years.
- Slightly more common in men than women.
- No specific risk factors identified; sporadic occurrence.
Clinical Features
- Autonomic dysfunction: Orthostatic hypotension, bladder dysfunction, sexual dysfunction.
- Parkinsonian features: Bradykinesia, rigidity, postural instability.
- Cerebellar ataxia: Impaired coordination, unsteady gait.
- Speech and swallowing difficulties.
Complications
- Progressive immobility leading to complications like falls and pneumonia.
- Severe autonomic dysfunction can lead to life-threatening complications.
- Progressive neurodegeneration leading to dependency in daily activities.
Pathological Features
Histopathology
- Macroscopic: Atrophy of the striatum, cerebellum, and brainstem.
- Microscopic: Glial cytoplasmic inclusions, neuronal loss, and neuroglian degeneration in multiple brain regions.
Serology
- Non-specific.
Biochemistry
- Non-specific.
Radiological Features
General Features
- Atrophy of the putamen, cerebellum, and brainstem.
- Hot cross bun sign on T2-weighted MRI, particularly in MSA-C. Classic sign but not pathognomic
CT
- Non-contrast: May show atrophy but less sensitive than MRI.
MRI
- T1: Atrophy of the putamen, cerebellum, and brainstem.
- T2: Hot cross bun sign – Cross-shaped hyperintensity within pons seen on axial; hyperintensities in the putamen.
- FLAIR: Shows atrophic changes and hyperintense signals in affected areas.
- SWI/GRE/T2*: May show iron deposition in the basal ganglia.
NM
- PET FDG: Can show reduced glucose metabolism in basal ganglia and cerebellum.
Grading and Staging
No specific grading or staging system; assessment is based on clinical severity and progression of symptoms.
Diagnosis
Diagnosis is primarily clinical, based on symptomatology and supported by MRI findings. Autonomic testing and neurophysiological studies can aid in diagnosis.
Differential Diagnosis
- Parkinson’s Disease: Absence of cerebellar signs and significant autonomic dysfunction.
- Progressive Supranuclear Palsy: Vertical gaze palsy, different pattern of neurodegeneration.
- Cerebellar Ataxia: Predominant cerebellar symptoms without significant autonomic or parkinsonian features.
Management
Management of MSA is symptomatic and supportive. This includes pharmacological treatment for parkinsonian symptoms, management of autonomic dysfunction, and physical therapy. Multidisciplinary care involving neurologists, urologists, and physical therapists is essential.