Gastric dysfunction in patients with chronic nausea and vomiting syndromes defined by a noninvasive gastric mapping device

Abstract

Chronic nausea and vomiting syndromes (NVSs) are prevalent and debilitating disorders. Putative mechanisms include gastric neuromuscular disease and dysregulation of brain-gut interaction, but clinical tests for objectively defining gastric motor function are lacking. A medical device enabling noninvasive body surface gastric mapping (BSGM) was developed and applied to evaluate NVS pathophysiology. BSGM was performed in 43 patients with NVS and 43 matched controls using Gastric Alimetry (Alimetry), a conformable high-resolution array (8 × 8 electrodes; 20-mm interelectrode spacing), wearable reader, and validated symptom-logging app. Continuous measurement encompassed a fasting baseline (30 minutes), 482-kilocalorie meal, and 4-hour postprandial recording, followed by spectral and spatial biomarker analyses. Meal responses were impaired in NVS, with reduced amplitudes compared to controls (median, 23.3 microvolts versus 38.0 microvolts, P < 0.001), impaired fed-fasting power ratios (1.1 versus 1.6, P = 0.02), and disorganized slow waves (spatial frequency stability, 13.6 versus 49.5; P < 0.001). Two distinct NVS subgroups were evident with indistinguishable symptoms (all P > 0.05). Most patients (62%) had normal BSGM studies with increased psychological comorbidities (43.5% versus 7.7%; P = 0.03) and anxiety scores (median, 16.5 versus 13.0; P = 0.035). A smaller subgroup (31%) had markedly abnormal BSGM, with biomarkers correlating with symptoms (nausea, pain, excessive fullness, early satiety, and bloating; all r > 0.35, P < 0.05). Patients with NVS share overlapping symptoms but comprise distinct underlying phenotypes as revealed by a BSGM device. These phenotypes correlate with symptoms, which should inform clinical management and therapeutic trial design.

Figure 1:

BSGM system and analysis pipeline. A) Outline of standardized BSGM test procedure.(27) B) The Gastric Alimetry Device, shown in closed and open profiles, during setup of the high-resolution array (8×8 pre-gelled Ag/AgCl electrodes), and in position overlying the epigastrium. C. Signal strength is visualized on an 8×8 electrode grid corresponding to the array, with the region of high-power activity corresponding to the gastric position in the mapped field.(27) D. BSGM analytics employed in this study comprised spectral metrics (power ratio, rhythm, dominant slow wave frequency; used for test classifications) and spatial metrics (measures of spatial slow wave stability; spatial frequency stability and average spatial covariance). Refer Methods for further detail.

Figure 2:

Average BSGM spectral plots (frequency-amplitude graphs), showing dominant frequencies on a scale from low power (dark blue) to high power (bright yellow), indicating gastric meal responses and rhythm, and with amplitude plots beneath, for healthy controls, NVS-N and NVS-Abn groups. The meal time and duration is indicated by a vertical blue bar at 30 min. Normal spectral plots (A, B) show a clear meal response (post-prandial power increase), a consistent and sustained frequency band, and a regular gastric rhythm (Methods and Fig. S1). C) Abnormal cases lacked these features. Individual subject examples from each category are provided in Fig. 3, and examples of normal and patient variations are provided in Fig. S3

Figure 3:

BSGM spectral plots (frequency-amplitude graphs), showing dominant frequencies on a scale from low power (dark blue) to high power (bright yellow), indicating gastric meal responses and rhythm, and with amplitude plots beneath. The mealtime and duration are indicated by a vertical blue bar. Normal spectral plots (A, B) show a clear meal response (post-prandial power increase), a consistent and sustained frequency band, and a regular gastric rhythm (Methods and Fig. S1). C) Abnormal cases lack these features. Examples of normal variants are provided in Fig. S3.

Figure 4:

Box plots of symptoms and metrics across controls, and those that had a positive (abnormal) and negative (normal) BSGM test in the NVS cohort. PAGI-SYM, Patient Assessment of Upper Gastrointestinal Disorders–Symptom Severity Index; GCSI, Gastroparesis Cardinal Symptom Index. STAI-SF; State-Trait Anxiety Inventory Short Form. ns; p>0.05, *; p≤0.05, **; p<0.01, ***; p<0.001, ****; p<0.0001.

Figure 5:

Top: Principal component analysis of healthy controls and NVS patients utilizing body surface gastric mapping metrics, symptom scores, and health psychology data. Below: case classifications.

Figure 6:

Wheel plot showing correlations between demographics, BSGM metrics, symptoms as measured by the PAGI-SYM subscales, quality of life and health psychology metrics in NSV groups. Correlations between quality-of-life metrics and symptoms are not reported, and only statistically significant correlations between categories are shown (after Hochberg correction). A: NVS-N cohort and controls; B: NVS-Abn cohort and controls.