title: Sacral nerve stimulation reduces corticoanal excitability in patients with faecal incontinence.
abstract: BACKGROUND
  Sacral nerve stimulation (SNS) can produce symptomatic relief in patients with faecal incontinence. Moreover, peripheral nerve stimulation has been shown to affect brain function. The aim of this study was to determine whether SNS might produce important changes in cortical activity linked to improved continence.
  
  
  METHODS
  In an experimental study, ten women with intractable faecal incontinence (mean age 51.3 years) were serially mapped with transcranial magnetic stimulation before and immediately after 14 days of temporary SNS (15 Hz, pulse width 210 micros), and then 2 weeks later. Anal sphincter electromyographic responses were recorded to cortical stimulation of multiple points over a scalp grid covering the bilateral medial cortex. Continence scores, anorectal manometry and rectal sensitivity data were also collected.
  
  
  RESULTS
  SNS improved global symptom scores in the majority of patients; mean(s.e.m.) continence scores fell from 16.9(1.6) to 10.6(1.8) (P = 0.042). Cortical mapping showed a consistent decrease in corticoanal representation and overall excitability immediately after SNS compared with baseline (mean(s.e.m.) 38,083(13,669) versus 42,507(13,297) microV s; P = 0.017), which was reversed 2 weeks after SNS wire removal.
  
  
  CONCLUSIONS
  SNS produces symptom benefit in patients with faecal incontinence that is associated with a reversible reduction in corticoanal excitability. SNS therefore drives dynamic brain changes that may play a functional role in influencing anal continence.
authors.affiliation: Department of Colorectal Surgery, South Manchester University Hospitals NHS Trust, Manchester, Salford, UK.
authors.forename: R
authors.initials: R
authors.lastname: Sheldon
authors.forename: E S
authors.initials: ES
authors.lastname: Kiff
authors.forename: A
authors.initials: A
authors.lastname: Clarke
authors.forename: M L
authors.initials: ML
authors.lastname: Harris
authors.forename: S
authors.initials: S
authors.lastname: Hamdy
mesh_terms: D000328:Adult; D000368:Aged; D001003:Anal Canal / Q000294:innervation*; D002540:Cerebral Cortex / Q000502:physiology*; D002908:Chronic Disease; D004599:Electric Stimulation Therapy / Q000379:methods*; D004574:Electromagnetic Fields; D004576:Electromyography; D005242:Fecal Incontinence / Q000503:physiopathology / Q000628:therapy*; D005260:Female; D006801:Humans; D008160:Lumbosacral Plexus; D008365:Manometry; D008875:Middle Aged; D011930:Reaction Time