From the Guidelines
Dysautonomia causes nausea by disrupting the autonomic nervous system's control over digestion, leading to slowed gastric emptying, orthostatic hypotension, and vagus nerve dysfunction. The pathophysiological mechanism involves the autonomic nervous system's role in modulating gastrointestinal motor, sensory, and secretory functions, as described in the study by 1. When the autonomic nervous system malfunctions, it can cause gastroparesis, leading to nausea and vomiting. Additionally, dysautonomia often affects blood pressure regulation, causing sudden drops in blood pressure that can trigger nausea, especially when changing positions. The vagus nerve, which helps regulate digestive processes, may become overactive or underactive in dysautonomia, further contributing to nausea symptoms. Some key points to consider include:
- The autonomic nervous system provides extrinsic innervation of gut function, via parasympathetic and sympathetic nerves, as noted in the study by 1.
- Parasympathetic innervation is both excitatory and inhibitory, whereas sympathetic input is generally inhibitory.
- The pathogenesis of gastrointestinal 'autonomic neuropathy' is complex and multifactorial, involving the interaction of autonomic and enteric nervous systems. Medications that can help manage dysautonomia-related nausea include antiemetics like ondansetron, promethazine, or metoclopramide, which also helps with gastric emptying, as well as treatments for the underlying dysautonomia, such as fludrocortisone, midodrine, or beta-blockers, as mentioned in the context of managing autonomic dysfunction 1. Non-pharmacological approaches, such as small, frequent meals, avoiding trigger foods, staying well-hydrated, and using compression garments to help maintain blood pressure, may also provide relief. Understanding the direct relationship between nausea and autonomic dysfunction is crucial in developing effective treatment strategies.
From the Research
Pathophysiological Mechanism of Dysautonomia-Induced Nausea
The pathophysiological mechanism by which Dysautonomia causes nausea is complex and involves the interplay of multiple systems, including the autonomic nervous system, central nervous system, and gastrointestinal tract.
- The autonomic nervous system plays a crucial role in regulating various bodily functions, including digestion and gut motility 2.
- Dysautonomia, a disorder characterized by altered function of the autonomic nervous system, can disrupt these regulatory processes, leading to nausea and other gastrointestinal symptoms 3, 4.
- The central pathways of nausea and vomiting involve the nucleus tractus solitarius, which receives signals from the gastrointestinal tract via the vagus nerve and relays them to the central pattern generator, initiating downstream pathways that can lead to nausea 2.
- The autonomic nervous system modulates these central pathways, and dysfunction of the autonomic nervous system, as seen in Dysautonomia, can alter this modulation, contributing to the development of nausea 2, 5.
- Additionally, the extended autonomic system, which includes neuroendocrine, immune/inflammatory, and central components, may also play a role in the pathophysiology of Dysautonomia-induced nausea 5.
- The homeostat theory, which proposes the existence of comparators that receive information about regulated variables and sense discrepancies between the information and response algorithms, may also be relevant to understanding the pathophysiological mechanisms of Dysautonomia-induced nausea 5.