Clinical condition	Pathology	Characteristics	Diagnosis	Treatment
Amyloidosis (hereditary and primary)	Deposition of amyloid protein in neural tissue	Generalized polyneuropathy, prominent pain, and temperature abnormalities; carpal tunnel syndrome; cardiomyopathy; diarrhea; weight loss	Fat aspirate; rectal or gingival biopsy for amyloid deposits; genetic testing for hereditary amyloidosis; serum and urine protein electrophoresis for primary amyloidosis	—
Diabetic autonomic neuropathy	Neuropathic changes associated with poor glycemic control	Associated with generalized polyneuropathy; other autonomic symptoms, including gastroparesis, diarrhea, urinary retention, and erectile dysfunction	Fasting blood glucose, glucose tolerance test, A1C	Glycemic control with oral hypoglycemic, insulin
Lewy body dementia	Lewy bodies in CNS, predominantly neocortical and limbic system	Autonomic dysfunction occurs early in course; parkinsonism; progressive dementia precedes or accompanies parkinsonism; fluctuating cognitive impairment; visual hallucinations	Cardiac SPECT shows impaired uptake of iobenguane I 123, especially with autonomic failure	—
Multisystem atrophy (Shy-Drager syndrome)	α-Synuclein precipitates in glial cells and CNS neurons	Severe, early autonomic dysfunction; parkinsonism; dysarthria; stridor; contractures; dystonia	Magnetic resonance imaging of brain shows changes in putamen, pons, middle cerebellar peduncle, and cerebellum	Autonomic support
Parkinson disease	Lewy bodies in cytoplasm of CNS neurons, resulting in extrapyramidal motor symptoms	Autonomic dysfunction occurs later, often as adverse effect of disease-specific therapy; parkinsonism; dementia	Cardiac SPECT shows impaired uptake of iobenguane I 123; positron emission tomography shows impaired uptake of 18 F-dopa	—
Pure autonomic failure	Lewy bodies in pre- and postganglionic neurons of peripheral autonomic nervous system	Gradually progressive autonomic dysfunction; no motor symptoms	Cardiac SPECT shows impaired uptake of iobenguane I 123	—