Chapter 10 - Autonomic neuropathies and gastroparesis

Abstract

Gastroparesis and other gastrointestinal motility diseases can be associated with various autonomic neuropathies. The gastrointestinal tract has its own enteric nervous system, a branch of the autonomic nervous system (ANS), and exchanges modulatory signals with the extrinsic autonomic systems. Autonomic neuropathies impairing functions of the extrinsic autonomic pathways can contribute to gastroparesis. Neurological evaluation is needed in patients with gastroparesis to assess systemic or extra-intestinal autonomic involvements as well as to identify an underlying neurological etiology. Self-assessed autonomic questionnaires such as composite autonomic symptom score (COMPASS) are feasible tools for such purposes. Autonomic reflex tests can localize impaired branches of the ANS and to support a diagnosis of autonomic neuropathy. Because autonomic reflex tests clinically available at most autonomic laboratories are relevant to cardiovascular and sudomotor (sweating) autonomic systems, findings of tests do not always have a strong association with the presence and severity of gastroparesis or other localized autonomic/neurological conditions. Skin biopsy to estimate sensory small-fibers in the epidermal layers and autonomic fibers innervating sweat glands is a pathological diagnostic method for small-fiber neuropathy. Autonomic neuropathies associated with gastroparesis include diabetic autonomic neuropathy, Guillain-Barré syndrome, autoimmune autonomic ganglionopathy, paraneoplastic autonomic neuropathy, hereditary amyloid neuropathy. Other autonomic disorders with or without evidence of peripheral autonomic nerve involvements such as postural orthostatic tachycardia syndrome are discussed. Ehlers-Danlos Syndrome is a hereditary connective tissue disorder with multiple subtypes but it is worth mentioning due to its high association with postural orthostatic tachycardia syndrome.