Pelvic Floor Dyssynergia Causing Constipation in a Patient With Prader-Willi Syndrome

Abstract

Introduction: Prader-Willi syndrome (PWS) is a multisystemic genetic disease present in 1/15,000-30,000 newborns. Constipation is very common in these patients as compared to the general population (40% vs 11%). The etiology of constipation in PWS may be multifactorial including a low fiber/high fat diet, rectal evacuation dysfunction due to decreased rectal sensation, reduced muscle tone, dyssynergic defecation (DD), or slow transit constipation. Data on the cause of constipation in PWS is limited and lacks use of objective testing such as anorectal manometry. Case Report: A patient with PWS was referred to a tertiary motility clinic for further evaluation of constipation. Patient was a 16-year-old female with PWS presenting with rectal pain and constipation for 2 years duration. Prior to that she was having 1 bowel movement (BM) daily. She notes having 1 soft BM every 5 days with a feeling of incomplete evacuation. Prior medications include polyethylene glycol, lubiprostone, milk of magnesia, and mineral oil leading to mild relief. She also uses bisacodyl as needed, magnesium citrate, and enemas weekly in order to have a BM. She notes passive fecal incontinence and has had to do manual disimpaction to aid with having a BM. Prior gastrographin enema mentioned a redundant sigmoid colon. Abdominal examination is unremarkable. On DRE she has a normal anocutaneous reflex with normal sphincter tone but an abnormal relaxation of puborectalis muscle. Both celiac serology and thyroid testing was normal. Anorectal manometry findings: Decreased resting pressure (52 mmHg), normal squeeze pressure (120 mmHg), normal RAIR and balloon expulsion. Rectal sensation testing was normal except for finding of rectal hypersensitivity (maximal tolerable volume of 160 ml only). An abnormal relaxation of the puborectalis and external sphincter muscles on push maneuvers was found suggesting DD. Patient was found to have DD with rectal hypersensitivity for which she was referred for biofeedback therapy. Constipation causing painful defecation and encopresis are highly prevalent in patients with PWS. In this case the symptoms are more likely to be caused by DD although wireless motility capsule was performed to rule out slow transit constipation. Discussion: DD may be a common finding in patients with PWS who commonly have other behavioral disorders associated with dyssynergia. Larger case series could help elucidate the role of diagnostic testing and biofeedback therapy in patients with PWS. We advocate performance of anorectal manometry to identify neuromuscular dysfunction in patients with PWS with subsequent biofeedback therapy depending on the degree of behavioral issues if dyssynergia is identified to minimize overuse of laxatives. Disclosure - Dr. Corral: no financial relationships. Dr. Kataria - no financial relationships. RN Vickers - no financial relationships. Dr. Koutouby - no financial relationships. Dr. Moshiree - Speaker’s Bureau: Gliven Imaging.