Reliability of electrophysiologic anal tests in predicting the outcome of sacral nerve modulation for fecal incontinence.
BACKGROUND
Sacral nerve modulation has been demonstrated to be a new efficacious treatment for fecal incontinence. The effectiveness of the procedure is preliminarily tested by means of a peripheral nerve evaluation. Integrity of the sacral neural pathway is generally believed to be a necessary condition for a good response, but no data are available to confirm whether electrophysiologic anal tests are predictive of the clinical outcome of the peripheral nerve evaluation.


METHODS
Eighty-two incontinent patients underwent the peripheral nerve evaluation after full evaluation of the anorectal physiology. Univariate analysis was performed, and the positive predictive value, sensitivity, and specificity were calculated for each of the tests.


RESULTS
Forty-six patients had successful results to the peripheral nerve evaluation and were subjected to permanent implant of a sacral electrostimulator. Anal sphincter electromyography had been performed in 60 patients, whereas pudendal nerve terminal motor latency had been assessed in 68 and evoked sacral potentials in 29 patients. Anal electromyography was statistically related to the outcome of the peripheral nerve evaluation ( P = 0.0004) with a positive predictive value of 81 percent, a sensitivity of 44 percent, and a specificity of 81 percent. Pudendal nerve terminal motor latency on the right side did not correlate with the outcome, but left pudendal nerve terminal motor latency was weakly correlated ( P = 0.02), although both tests had a low positive predicting value and sensitivity vs. good specificity. Evoked sacral potentials did not correlate with the outcome and had a low positive predictive value, sensitivity, and specificity.


CONCLUSIONS
Simple anal sphincter electromyography can predict the outcome of the peripheral nerve evaluation with good positive predictive value and specificity in patients with fecal incontinence. Other, more expensive, electrophysiologic anal tests do not add further prognostic information.
Altomare
Donato F
DF
Department of Emergency and Organ Transplantation, General Surgery and Liver Transplantation Units, University of Bari, Bari, Italy. altomare@clichiru.uniba.it
Rinaldi
Marcella
M
Petrolino
Maria
M
Ripetti
Valter
V
Masin
Alessandra
A
Ratto
Carlo
C
Trerotoli
Paolo
P
Monitillo
Vincenzo
V
Lobascio
Pierluigi
P
De Fazio
Michele
M
Guglielmi
Altomarino
A
Memeo
Vincenzo
V
D000368:Aged; D001003:Anal Canal / Q000503:physiopathology* / Q000601:surgery; D004567:Electrodes, Implanted; D004576:Electromyography / Q000379:methods*; D005242:Fecal Incontinence / Q000503:physiopathology* / Q000601:surgery*; D005260:Female; D006801:Humans; D008160:Lumbosacral Plexus / Q000503:physiopathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D019919:Prosthesis Implantation / Q000379:methods; D015203:Reproducibility of Results; D012189:Retrospective Studies; D016896:Treatment Outcome