Spontaneous Internal Anal Sphincter Relaxation During High-resolution Anorectal Manometry Is Associated With Peripheral Neuropathy and Higher Charlson Comorbidity Scores in Patients With Defecatory Disorders

Abstract

Background/AimsWe aimed to evaluate associations between comorbidities, peripheral neuropathy, and spontaneous internal anal sphincter relaxation (SAR) in patients with defecatory disorders. MethodsA patient was considered to exhibit SAR during high-resolution anorectal manometry (HR-ARM) when the nadir pressure is < 15 mmHg and the time from onset to relaxation was ≥ 15 seconds in the resting pressure frame. A case-control study was performed using HR-ARM data collected from 880 patients from January 2010 to May 2015. We identified 23 cases with SAR (median age 75 years; 15 females; 12 fecal incontinence and 11 constipation). We compared HR-ARM values, Charlson index comorbidity scores, neuropathy, and the prevalence of diseases that potentially cause neuropathy between controls and SAR patients. Each SAR case was compared to 3 controls. Controls were selected to match the age, gender, and examination year of each SAR case. ResultsCompared to controls (26.1%), SAR patients (52.2%) exhibited a significantly higher frequency of fecal incontinence. SAR patients also had higher Charlson index scores (5 vs 4, P = 0.028). Nine of 23 SAR patients (39.1%) exhibited peripheral neuropathy-this frequency was higher than that for the control group (11.6%; P = 0.003). Diseases that potentially cause neuropathy were observed in 17 of 23 SAR cases and 32 of 69 controls (P = 0.022). ConclusionsSAR develops in patients with constipation and fecal incontinence but is more common in patients with fecal incontinence. Our controlled observational study implies that SAR is associated with peripheral neuropathy and more severe comorbidities.

Transient Anal Sphincter Relaxations Are a Normal Phenomenon in Healthy Subjects: Author‘s Reply

“…In our study, TAR patients (median score = 5) had a higher median Charlson comorbidity index score than controls (median score = 4, P = 0.003). 5 Peripheral neuropathy was also significantly more common in TAR patients (39.1%) than in controls (11.6%, P = 0.022). 4 There was a significant difference between the TAR patients (72.7%) and the controls (41.2%) regarding the presence of diseases that potentially cause peripheral neuropathy.…”

“…In our study, the proportion of constipation among SAR patients was 47.8%. 5 Given that, SAR is unlikely to contribute to FI.…”

“…6 Additionally, the TAR patients had a significantly higher incidence of diseases that potentially cause peripheral neuropathy. 5 There is, meanwhile, a controversy that FI and constipation is related to increased mortality. 7,8 This controversy might be due to the presence of the accompanying TAR finding.…”

Transient Anal Sphincter Relaxations Are a Normal Phenomenon in Healthy Subjects

“… 2 Relaxation of the internal anal sphincter (IAS) during anorectal manometry can also occur “spontaneously,” named spontaneous internal anal sphincter relaxation (SAR), when it is not associated with a stimulus. A recent study suggested that such an occurrence of a SAR indicates an “unstable IAS contraction” that “likely plays an important role in the development of fecal incontinence.” 3 Six hundred and one patients with defecation disorders were assessed, only 23 of which exhibited SAR during anorectal manometry. The authors concluded that SAR was associated with neuropathy, 3 but no evidence was presented that there is a causal relationship.…”

“…A recent study suggested that such an occurrence of a SAR indicates an “unstable IAS contraction” that “likely plays an important role in the development of fecal incontinence.” 3 Six hundred and one patients with defecation disorders were assessed, only 23 of which exhibited SAR during anorectal manometry. The authors concluded that SAR was associated with neuropathy, 3 but no evidence was presented that there is a causal relationship. The 23 patients were compared with 69 patients without SAR, randomly chosen from the same group.…”