Pure autonomic failure and multiple system atrophy

Abstract

Pure autonomic failure (PAF) and multiple system atrophy (MSA) are neurodegenerative disease that present with severe autonomic dysfunction, and their diagnosis is often difficult. According to the current MSA diagnostic criteria, probable MSA requires a sporadic, progressive adult–onset disorder including rigorously defined autonomic failure and poorly levodopa–responsive parkinsonism (MSA–P) or cerebellar ataxia (MSA–C). MSA–P is thought to be almost the same as striatal substantia nigra degeneration (SND), MSA–C is thought to be almost the same as olivopontocerebellar atrophy (OPCA). On the other hand, there is no “MSA-A” equivalent to Shy–Drager syndrome. Even in case that autonomic failure is the main symptom and it is difficult to distinguish from PAF, it is necessary to diagnose MSA–P or MSA–C from slight motor symptoms.

PAF and MSA present with severe systemic autonomic dysfunction in the urinary system, cardiovascular system, gastrointestinal tract, skin, sweat glands, etc., and the autonomic failure worsens as the stage progresses. Pathologically, PAF mainly consists of sympathetic ganglion and postganglionic lesion, whereas MSA has central or preganglionic lesions such as vagal nerve lateral nucleus, locus coeruleus, spinal cord medial lateral nucleus, and sacral Onuf nucleus.

Therefore, it is effective to evaluate the lesion of autonomic dysfunction to diagnose PAF and MSA. In general, cardiovascular autonomic nervous function and urinary autonomic nervous function test are often used in combination. However, the diagnostic sensitivity is not particularly high in the early stage of the disease. So, we make a comprehensive diagnosis while evaluating other autonomic nerve function such as cutaneous sympathetic function and electrogastrrogram.