While a recent study (A Darbari et al JPGN 2016; 63: 329-35) provides some interesting data regarding the potential origin of gastrointestinal symptoms in the setting of orthostatic intolerance, I cannot support their conclusion that antroduodenal manometry (ADM) “should” be part of the evaluation of these affected children.
- Retrospective study which included only subjects with a positive tilt test
- Among 35 children with orthostatic intolerance due to either neurally mediated hypotension (NMH) or postural orthostatic tachycardia syndrome (POTS), ADM was abnormal at baseline or during tilt table testing in 26 (75%).
- ADM studies were more often abnormal than gastric emptying studies, which were normal in 12 or 25.
- Specific findings included neurogenic intestinal dysmotility in 15, antral hypomotility in 4, visceral hyperalgesia in 2, and regurgitation in 5.
- GI symptoms of nausea, abdominal pain or vomiting were reproduced during tilt testing in 31 of 35 patients (89%).
Based on the discussion, the authors imply that ADM testing could help determine if the symptoms are due to neurogastrointestinal pathology or if normal, could indicate a central origin for the GI symptoms. Thus, they conclude that motility testing “should” be part of comprehensive” orthostatic intolerance evaluation.
I would argue that this study does not show that ADM testing can reliably distinguish whether symptoms are due to a neurogastroenterological pathology or central pathology. And, in fact, there are better tests to examine for central origin. I wouldn’t be surprised if many of their subjects had brain imaging, though this is not reported.
In addition, the authors acknowledge that ADM testing may not influence therapeutic decisions. “The clinical response to promotility agents in children with POTS is generally low.”
My take: This study provides a useful mechanistic explanation of symptoms associated with orthostatic intolerance. However, “I’m not there yet” on supporting ADM for all children with OI.
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