title: The effect of sacral nerve modulation on cerebral evoked potential latency in fecal incontinence and constipation.
abstract: OBJECTIVE
  Influence of sacral nerve modulation (SNM) on cerebral somatosensory evoked potentials (SEP) was determined in patients with incontinence and constipation.
  
  
  BACKGROUND
  Selection of patients with incontinence and constipation for SNM could be improved.
  
  
  METHODS
  The latency (ms) of SEP induced by pudendal nerve stimulation was compared before (T0) and at 1 month during peripheral nerve evaluation (PNE) of SNM at frequencies of 21 Hz (T1) and 40 Hz (T2). The results were correlated with clinical outcome at 6 months.
  
  
  RESULTS
  In 16 of 23 incontinent patients with clinical "success" from SNM (Wexner incontinence score ≤7), there was a significant difference between P40 latency at T0 and T2 (38.81 vs. 37.49 ms, P = 0.049). In the 7 with "failure," there was no change between T0 and T2. In 12 of 19 constipated patients with "success" (Wexner constipation score ≤15), there was no difference between T0 and T2 P40 latency (39.28 vs. 38.25 ms, P = 0.374). In the 7 with "failure," there was a significant fall in P40 latency (41.20 vs. 39.30 ms, P = 0.047) but not to the normal range. The T0 P40 latency in incontinent patients having "success" was significantly higher than in the normal range (P = 0.044). In constipated patients it was significantly higher than in the normal range in both those with "success" (P = 0.001) and "failure" (P = 0.022).
  
  
  CONCLUSIONS
  Measurement of P40 latency of SEP at baseline and at 1 month of SNM at a frequency of 40 Hz may help to predict the outcome of SNM and thus influence the decision for permanent implantation for patients with incontinence and constipation.
authors.affiliation: Colorectal Eporediensis Centre-Gruppo Policlinico di Monza, Divisione di Chirurgia Colorettale, Clinica Santa Rita, Vercelli, Italy.
authors.forename: Iacopo
authors.initials: I
authors.lastname: Giani
authors.forename: Eugenio
authors.initials: E
authors.lastname: Novelli
authors.forename: Stefania
authors.initials: S
authors.lastname: Martina
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Clerico
authors.forename: Alberto Realis
authors.initials: AR
authors.lastname: Luc
authors.forename: Mario
authors.initials: M
authors.lastname: Trompetto
authors.forename: Silvia
authors.initials: S
authors.lastname: Malaguti
authors.forename: John
authors.initials: J
authors.lastname: Nicholls
authors.forename: Ezio
authors.initials: E
authors.lastname: Ganio
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003248:Constipation / Q000503:physiopathology* / Q000628:therapy*; D005073:Evoked Potentials, Somatosensory; D005242:Fecal Incontinence / Q000503:physiopathology* / Q000628:therapy*; D005260:Female; D006801:Humans; D058542:Implantable Neurostimulators; D008160:Lumbosacral Plexus; D008297:Male; D008875:Middle Aged; D011930:Reaction Time