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Animal models of colitis commonly use inflammatory agents like dextran sodium sulfate (DSS) or 2,4,6-trinitrobenzenene sulfonate (TNBS) along the luminal membrane. Electrical vagal stimulation has been demonstrated in two studies to decrease inflammation in these kinds of models, but neither study looked into which vagal neurons are involved [78,168]. In a small pilot trial, seven patients with ileocolonic Crohn's disease were placed with cervical vagus nerve electrodes and continuously stimulated for 6 months [79]. The device was well tolerated, with only a few reports of throat pain and vocal changes during the ON phases. Two patients with a more severe form of Crohn's disease dropped out due to worsening symptoms; however, the remaining five patients achieved clinical and endoscopic remission, one of whom stayed in remission for 42 months after surgery and no longer required azathioprine.

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Ileus, also known as gut stasis, is a serious illness which commonly occurs after abdominal surgery or injury [169]. Previously, drugs that target inflammatory processes (such as nonsteroidal anti-inflammatory drugs), inhibitory neural pathways (such as antiadrenergic), or motility-stimulating mechanisms (such as metoclopramide) were utilised to prevent and treat this condition [170]. VNS has been successful in the prevention and management of ileus in a rat model caused by small intestine manipulation [171,172]. The efficacy of stimulating vagal pathways to treat ileus was also demonstrated in a rat model in which the vagus nerve was activated through pharmacological stimulation (injection of a thyrotropin-releasing hormone agonist across the CNS) [173]. Vagal stimulation inhibited inflammation, which prevented gut transit from slowing down. Another study, in which ileus was induced in rats via intestinal manipulation, found that indirect electrical stimulation of vagal pathways could prevent ileus without preventing inflammation [174]. Gastroparesis is a chronic disorder marked by delay in gastric emptying despite the absence of obstruction, in addition to postprandial discomfort, nausea, and vomiting [175]. Pharmaceutical treatments for this condition are ineffective[176,177]. Electrical stimulation to the gastric corpus with variables that stimulate vagal afferent fibres has been shown to reduce nausea and postprandial satiety [178,179]. One review and one meta-analysis of Gastric Electrical Stimulation (GES) for the management of gastroparesis published in recent years found that it was only effective in some trials [176,180]. The meta-analysis discovered that even though 16 open label, follow-up trials indicated overall symptom score reductions (nausea or nausea and vomiting, postprandial discomfort), 5 studies assessing symptoms with stimulation turned on or off randomly (patients serving as controls) found no difference between the on and off conditions[181].