Gastric Electrical Stimulation for Abdominal Pain in Patients With Gastroparesis

Change from baseline in seven-day average of daily worst abdominal pain score measured using an 11-point Numeric Rating Scale (0 = no pain, 10 = worst possible pain).

Change in Brief Pain Inventory (BPI) score from baseline to 8 weeks after randomization. The investigators will be using the Brief Pain Inventory (BPI) short form.

The Brief Pain Inventory (BPI) scoring assesses pain severity and its interference with daily life using an 11-point numeric rating scale (0 = "no pain/interference", 10 = "worst pain/complete interference").

It provides two main scores: a Pain Severity Score (average of 4 items) and a Pain Interference Score (average of 7 items), where higher scores indicate greater impairment.

Change in Gastroparesis Cardinal Symptom Index (GCSI) score from baseline to 8 weeks after randomization. The Gastroparesis Cardinal Symptom Index (GCSI) is a patient-reported tool measuring the severity of gastroparesis symptoms over 2 weeks, assessing 9 items group into 3 subclasses: nausea/vomiting, fullness/early satiety, and bloating on a 0-5 scale. A total GCSI score ≥18 generally indicates moderate to severe symptoms, with lower scores indicating better symptom control.

Change in use of opioid and non-opioid pain medications during the 8-week randomized treatment period.

Percent of responders defined as ≥30% reduction in pain score at 8 weeks.

The investigators will be using the Brief Pain Inventory (BPI) short form. The Brief Pain Inventory (BPI) scoring assesses pain severity and its interference with daily life using an 11-point numeric rating scale (0 = "no pain/interference", 10 = "worst pain/complete interference"). It provides two main scores: a Pain Severity Score (average of 4 items) and a Pain Interference Score (average of 7 items), where higher scores indicate greater impairment.

Measured via serum testing including including IL-6, TNF-α, IL-1β, IL-8, and IFN-γ.

For measurements of autonomic function, participants will undergo traditional autonomic testing, an established technique that has been extensively applied. This testing is reported a two main components: Vagal Cholinergic, via RR variation with deep breathing and Valsalva Ratio as well as Sympathetic Adrenergic, via postural adjustment ratio and vasoconstriction to cold stress.

The normal values for these are derived from extensive experience of nearly 3000 patients as well as normal controls. This testing is also performed with cutaneous electrograms, used as a combined autonomic enteric tool, for baseline, and response to cold and posture.

Measured via electrogastrogram (EGG). The investigators will record mucosal and serosal measures at the time of placement of temporary GES electrodes, and before a temporary GES device is connected to the leads. The technique of mucosal electrogram recordings uses 2 leads, a proximal one in the upper gastric body and a distal one near the body antral junction, which allows for low resolution mapping of the stomach. The recordings will be analyzed by signal averaging and reported as frequency, amplitude and their ratio. All patients will also have baseline cutaneous electrograms as well, for reference, analyzed in a similar manner.