Clinical Sympathetic Imaging

Publisher Summary This chapter explains how sympathetic imaging provides an important supplement to physiological, neurochemical, and neuropharmacological approaches in the evaluation of patients with clinical autonomic disorders. Neuroimaging assessments can be categorized in terms of anatomic, functional nonspecific, and functional specific. Examples of anatomic neuroimaging are computed tomography and magnetic resonance imaging of the brain. Cardiac sympathetic images therefore look like myocardial perfusion scans. Other thoracic organs and tissues possess much lower concentrations of sympathetic nerves. I-metaiodobenzylguanidine (I-MIBG) is an analog of the sympathomimetic amine, guanethidine, which differs structurally from norepinephrine, the neurotransmitter that mediates sympathetic regulation of the cardiovascular system. Lewy body diseases such as Parkinson's disease, dementia with Lewy bodies, and pure autonomic failure are characterized by intraneuronal precipitates of the protein alpha-synuclein. Cardiac sympathetic imaging and postmortem neuropathologic findings have linked alpha-synucleinopathy with noradrenergic denervation in Lewy body diseases. Thus, patients with familial Parkinson's disease from abnormalities of the gene encoding alpha-synuclein have cardiac sympathetic denervation.