Sacral Nerve Function in Child Patients After Ileal J-Pouch-Anal Anastomosis for Ulcerative Colitis

To clarify the neurological function of the puborectalis muscle (PM) in child patients with soiling after ileal J-pouch-anal anastomosis (IPAA) for ulcerative colitis (UC), we examined the terminal motor latency in the sacral nerves that regulate the PM. Eight patients after IPAA for UC were studied (6 males and 2 females aged 11 to 13 years with a mean age of 12.8 years). All patients 6 months after IPAA showed soiling (group A) and these patients showed continence at 2 years after IPAA (group B). Group C serving as controls consisted of 16 subjects (10 males and 6 females aged 12 to 17 years with a mean age of 14.4 years). Left- and right-sided sacral nerve terminal motor latency (SNTML) tests were performed at 6 months and 2 years after IPAA in order to measure the latency of the response in the bilateral PM following magnetic stimulation of sacral nerve root segments 2 to 4 (S2–S4) of the spinal column overlying the cauda equina. The following results were obtained. (1) Right-sided SNTML: group A exhibited significant prolongation compared with groups B and C (P < 0.0001 and P < 0.0001, respectively). There was no significant difference between groups B and C (P = 0.2329). (2) Left-sided SNTML: group A exhibited significant prolongation compared with groups B and C (P = 0.0002 and P < 0.0001, respectively). There was no significant difference between groups B and C (P = 0.2315). Note that significant differences were not established between SNTML values measured on the right and left sides. Soiling in child patients 6 months after IPAA may be caused by damage to the bilateral sacral nerves during the operation. However, the damage to the sacral motor nerve improves within 2 years after IPAA.Key words: Soiling, Sacral nerve terminal motor latency, Puborectalis muscle, Ulcerative colitis, ChildThe functional results of total colectomy, mucosal proctectomy, and ileal J-pouch-anal anastomosis (IPAA) for ulcerative colitis (UC) have been acceptable and patient satisfaction has been very high because patients are free from stoma.^1–3 In general, the functional outcomes after IPAA in children are better than those in adults.^4–12 However, some child patients experience defecation function impairments after IPAA, including minor fecal incontinence (soiling), incontinence, increased bowel movement, urgency of defecation, evacuation difficulty, irregular bowel habitus, difficulty in distinguishing gas from feces, and diarrhea.^8–10,12 The most common abnormality is soiling.^8–10 Soiling in both children and adults is usually more severe in the early postoperative period of about 3 to 6 months after operation and improves with time, but may become permanent more than 1 year after IPAA.^3–6,9 Generally, the frequency of soiling in child patients more than 1 year after IPAA is 0 to 12%,^4–6,8,9,12 and in adults 30 to 40%.^2,13,14 Over the past 20 years or so, the function of the anorectum in patients with soiling after IPAA has been studied in depth using anorectal manometry.^15–17 According to the data of anorectal manometry in child patients after IPAA, the anal sphincter complex comprising the internal anal sphincter and external anal sphincter is important to prevent soiling.¹⁷ In contrast, the puborectalis muscle (PM) was considered the most important factor preventing soiling in other studies not using anorectal manometry, which cannot detect the function of the PM, although less is known about the neurological functions in patients with soiling after IPAA in regard to the sacral nerve (SN) that regulates the PM.^18–20 To the best of our knowledge, there are no reports of electrophysiological studies of SN in child patients with soiling after IPAA for UC. We therefore studied bilateral SN function using sacral nerve terminal motor latency (SNTML) in child patients with soiling 6 months after IPAA and the same patients without soiling 2 years after IPAA for UC.