Chapter 23 - Multiple System Atrophy

Abstract

A progressive neurodegenerative disorder, multiple system atrophy (MSA) presents clinically with varying degrees of Parkinsonism, autonomic dysfunction, and impaired cerebellar function. The current nomenclature utilizes the abbreviations MSA-P to indicate that parkinsonism dominates the clinical presentation, and MSA-C to indicate that cerebellar ataxia predominates. Current diagnostic criteria utilize clinical domains, features, and criteria to define possible, probable, and definite MSA. Diagnosis can be aided by anatomical imaging with magnetic resonance imaging (MRI), which reveals hypo intensity in the putamen and a hyperintense rim lateral to the putamen in T2 weighted MRI scans in many cases of MSA. Functional imaging with positron emission tomography (PET) utilizing ligands to study cerebral glucose metabolic rates, striatal dopaminergic terminals, and striatal dopaminergic and opiate receptors can also assist diagnosis. Functional imaging with single photon emission computed tomography (SPECT) using striatal presynaptic and postsynaptic dopaminergic ligands also provides helpful diagnostic information. SPECT studies of cardiac innervation reveal postganglionic autonomic failure in Parkinson's disease but not in MSA, as autonomic failure occur in the preganglionic neuron in MSA. The neuro-pathological features in MSA include neuronal degeneration affecting principally the nigrostriatal, olivopontocerebellar, and central autonomic structures and very large numbers of abnormal tubular structures termed glial cytoplasmic inclusions (GCIs). These abnormal structures also appear in oligodendrocyte cytoplasm, oligodendrocyte nuclei, neuronal cytoplasm, neuronal nuclei, and axons.