Gastric neuromodulation with Enterra system for nausea and vomiting in patients with gastroparesis

Objective: Gastric electrical stimulation (GES) has been introduced for treating gastric motility disorders, such as gastroparesis, and obesity. A special method of GES using high frequency-short pulses, called Enterra® Therapy, has been clinically applied to treat nausea and vomiting in patients with gastroparesis. However, its mechanisms are not well understood. Materials and Methods: General methodologies of GES published in the literature are systematically reviewed and their main effects and application are presented. The major part of this review is focused on Enterra Therapy since this is the only method that has been used clinically. A number of different GES methods have been proposed. Results: GES with long pulses or dual pulses, but not short pulses, are able to alter (enhance or inhibit) such parameters of gastric motility as gastric slow waves and gastric emptying. Synchronized GES has been reported to improve antral contractions. GES with high frequency-short pulses, or Enterra Therapy, is known to improve nausea and vomiting in patients with gastroparesis and has a response rate of 50-70%. Improved gastric accommodation, direct enteric nervous system effects, enhanced vagal activity, and activation of central neurons are believed to be the underlying mechanisms involved in the antiemetic effect of this therapy. Conclusions: GES with high frequency-short pulses effectively reduces nausea and vomiting in patients with gastroparesis. This antiemetic effect could be mediated via enteric, autonomic, and/or central neural mechanisms. Further systematic and controlled studies are needed to improve the efficacy of Enterra Therapy and to understand its mechanisms of action.