Gastrocolonic Response

Sacral nerve stimulation effect on colonic motility in pediatric patients

BACKGROUND

Sacral nerve stimulation (SNS) is a minimally invasive surgical procedure used to treat refractory constipation in children. While its efficacy in improving symptoms has been studied, its effect on colonic motor function remains unclear. This case series explores SNS's impact on colonic motor function in pediatric patients with idiopathic constipation, using high-resolution colonic manometry (HRCM).

METHODS

Four pediatric patients with chronic idiopathic constipation underwent SNS placement for intractable symptoms and were subsequently evaluated via HRCM. Clinical characteristics, comorbidities, treatment regimens, and outcomes were reviewed. HRCM was conducted during the SNS-off and SNS-on phases. The motility index (MI) was measured during the SNS-off (fasting and postprandial) and SNS-on phases.

RESULTS

Four pediatric patients aged 8 to 21 years met the inclusion criteria. In three patients, SNS-induced high-amplitude propagating contractions (HAPCs) were noted, and in one patient, low-amplitude propagating contractions (LAPCs) were noted. In one patient, propagating contractions were induced only when SNS was turned on. MI changes with SNS-on were variable among different patients with an increase in MI in two patients after turning SNS on and a decrease in the other two compared with baseline. Adverse effects following SNS placement remained minimal across all cases.

CONCLUSION

This case series is the first to report SNS effects on colonic motility evaluated by HRCM in pediatrics. We demonstrate that propagating colonic contractions are promptly induced when SNS is turned on. Although the initial effects of SNS on colonic motility were observable, additional investigation is necessary to comprehend the fundamental mechanisms and long-term effectiveness of SNS in pediatric patients.

Exploring Diagnostic Priorities: The Role of Colonic Manometry in Evaluating Pediatric Patients with Intractable Idiopathic Constipation Prior to Sacral Nerve Stimulation

BACKGROUND

Despite the limited understanding of its precise mechanism of action, sacral nerve stimulation (SNS) has proven to be helpful for pediatric patients with constipation, particularly those with fecal incontinence. It is unclear whether the outcome of SNS is impacted by normal or abnormal colonic motility. Our study aimed to determine whether colonic manometry results had an impact on the outcome of SNS as a treatment in pediatric patients with refractory idiopathic constipation.

METHODS

Electronic medical records of patients with idiopathic constipation who underwent colonic manometry and SNS placement at our center over 6 years were reviewed. A comparison of post-SNS outcomes was performed between patients with normal and abnormal colonic manometry studies.

RESULTS

Twenty patients [12 (60%) females, median age of 10.2 years] met inclusion criteria, with fecal incontinence in 12 (60%) and abnormal colonic manometry in 6 (30%). Significantly more patients had an improvement in fecal incontinence following SNS placement (p = 0.045). There were no significant differences in post-SNS constipation outcome measures between patients with normal versus abnormal colonic manometry.

CONCLUSIONS

Colonic manometry did not help with patient selection for those being considered for SNS therapy. Our findings do not support performing colonic manometry as a screening prior to SNS placement.

Diagnostic yield of left-sided colonic manometry in identifying colonic dysmotility in pediatric patients

BACKGROUND

Colonic manometry (CM) is a diagnostic procedure utilized in the evaluation of intractable constipation and involves endoscopic insertion of a manometry catheter with the tip placed in the cecum. Difficulty in advancing the colonic manometry catheter to the right colon and/or distal displacement of the catheter after appropriate placement can result in partial evaluation of the colon. Our study aimed to assess the value of limited left CM in identifying motility disorders.

METHODS

We evaluated CM studies conducted at a tertiary pediatric center (2019-2022). Abnormal CM studies with catheter tips located in the cecum or ascending colon were included.

KEY RESULTS

Of 161 CM studied, 68 with abnormal CM studies met inclusion criteria (29 [42.7%] females, median age 10.3 years). Pan-colonic dysmotility was noted in 29 (42.7%) studies and segmental dysmotility in 39 (57.4%) studies. Dysmotility of the descending and/or sigmoid colon was the most common segmental dysmotility (30, 76.9%). Isolated dysmotility of the ascending colon was noted only in patients with a cecostomy (6/13, 46.2%). The diagnostic sensitivity for dysmotility by left CM was 91.2%, which increased to 100% when excluding patients with cecostomy.

CONCLUSIONS AND INFERENCES

Left CM is a valuable and sensitive diagnostic tool for identifying abnormal colonic motility in most pediatric patients with constipation without cecostomy. Our study results provide reassurance when the manometry catheter becomes dislodged from the cecum and moves distally. Those with cecostomy have a high prevalence of dysmotility in the ascending colon and need a complete CM to identify it.

Circadian rhythms in colonic function

A rhythmic expression of clock genes occurs within the cells of multiple organs and tissues throughout the body, termed "peripheral clocks." Peripheral clocks are subject to entrainment by a multitude of factors, many of which are directly or indirectly controlled by the light-entrainable clock located in the suprachiasmatic nucleus of the hypothalamus. Peripheral clocks occur in the gastrointestinal tract, notably the epithelia whose functions include regulation of absorption, permeability, and secretion of hormones; and in the myenteric plexus, which is the intrinsic neural network principally responsible for the coordination of muscular activity in the gut. This review focuses on the physiological circadian variation of major colonic functions and their entraining mechanisms, including colonic motility, absorption, hormone secretion, permeability, and pain signalling. Pathophysiological states such as irritable bowel syndrome and ulcerative colitis and their interactions with circadian rhythmicity are also described. Finally, the classic circadian hormone melatonin is discussed, which is expressed in the gut in greater quantities than the pineal gland, and whose exogenous use has been of therapeutic interest in treating colonic pathophysiological states, including those exacerbated by chronic circadian disruption.

Novel sensory trigger for gastrocolonic response

BACKGROUND

Gastrocolonic response (GCR) is a physiologic increase in motor activity of the colon following meal ingestion. The presence of GCR, in colonic manometry (CM) studies, is used as a marker of normal colonic motor activity. Our aim was to investigate whether GCR could be induced by sensory stimulation (visual or olfactory) prior to food ingestion, and to describe the characteristics of patients with this response.

METHODS

We prospectively marked time of meal presence and initiation on CM tracings of patients with idiopathic constipation. We reviewed electronic medical records and normal CM studies. Presence of sensory GCR was defined as an increase by at least 25% of the baseline motility index (MI) after exposure to meal, prior to food ingestion. Manometry characteristics of patients with a sensory GCR response were compared to those without.

KEY RESULTS

Eighty-nine patients, (47% females, median age 9 years) met the inclusion criteria. Forty-seven (52.8%) patients had a positive sensory GCR. This cohort had a higher proportion of postprandial GCR (93.6% vs. 76.2%, p-value = 0.02) and lower fasting MI (2.08 mm Hg vs. 3.54 mm Hg, p < 0.01). Thirteen (14.6%) patients who had no postprandial GCR had higher baseline MI (median of 3.69 vs. 2.46 mm Hg, p < 0.05).

CONCLUSIONS & INFERENCES

Visualizing or smelling food resulted in a significant increase in baseline MI in more than 50% of patients. Our findings propose a novel, alternate pathway that can induce GCR. This central sensory pathway may have clinical relevance in the diagnosis and management of patients with colonic dysmotility.