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30 Neuromodulation for Fecal Incontinence: Outcome in 16 Patients with Definitive Implant [2001년 7월 DCR] 2011-11-17 3574
 
The Initial Italian Sacral Neurostimulation Group (GINS) Experience
 
E. Ganio, M.D., C. Ratto, M.D., A. Masin, M.D., A. Realis Luc, M.D.,G. B. Doglietto, M.D.,J- G. Dodi, M.D., V. Ripetti, M.D., A. Arullani, M.D.,M. Frascio, M.D, E. BertiRiboli, M.D., V. Landolfi, M.D.,C A. DelGenio, M.D.,D. F. Altomare, M.D., V. Memeo, M.D., P. Bertapelle, M.D., R. Carone, M.D.,M. Spinelli, M.D.N- A. Zanollo, M.D., L. Spreafico, M.D., G. GiaMiello, Ph.D.,F. de Seta, Ph.D.
 
From the Colorectal-Eporediensis-Centre, Ivrea, Italy; tPoliclinico A. Gemelli, Istituto di Clinica cbirurgica, and Ospedale Franchini, Montecchio Emilia, Roma, Italy,. Clinica Chi,rgica II Padova, Padova, italy; Chirurgia Generale Bari, Bari, Italy; Campus Biomedico, Roma, Italy; II Universitd di Napoli, Clinica Cbirurgica Esofagogastreoenterologia, Napoli, Italy; ][Clinica Chirurgica, Osp. S. Martino Genova, Genova, Italy,. Dipartimento Urotogia, CTOCRFMA, Torino, Italy; Dipaimento Urotogia, Ospedale C. Magenta; and Medtronic Italia
 
PURPOSE: Sacral nerve modulation appears to offer a valid treatment option for some patients with fecal incontinence and functional defects of the internal anal sphincter or of the striated muscle. METHODS: Sixteen patients with fecal incontinence (4 males; mean age, 51.4 (range, 27-79)years)
with intact or surgically repaired (n = 1) anal sphincter underwent permanent sacral nerve stimulation implant. Cause was traumatic in two patients, and associated disorders included scleroderma (2 patients) and spastic paraparesis (1 patient); eight (50 percent) of the patients also had urinary incontinence, and two (12.5 percent) had nonobstructive urinary retention. All patients were selected on the basis of positive findings from at least one peripheral nerve evaluation. The stimulating electrode was positioned in the S2 (1 patient), S3 (14 patients), or S4 (1 patient) sacral foramen.
RESULTS: Mean follow-up was 15.5 (range, 3-45) months. Mean preimplant "Williams score decreased from 4.1 + 0.9 (range, 2-5) to 1.25 + 0.5 (range, 1-2) (P = 0.01,Wilcoxon test), and the number of incontinence accidents for liquid or solid stool in 14 days decreased from 11.5 --_4.8 (range, 2-20) before implant to 0.6 -4- 0.9 (range, 0-2) at the last follow-up. Important manometric data were an increase in mean maximal pressure at rest of 37.7 + 14.9 manHg (implantable pulse generator 49.1 -+ 18.7, P = 0.04) and in mean maximal pressure during squeeze (prestimulation 67.3 --- 21.1 mmHg, implantable pulse generator 82.6 _+ 21.0, P = 0.09).
CONCLUSIONS: Neuromodulation can be considered an option for fecal incontinence. However,
an accurate clinical and instrumental evaluation and careful patient selection are required to optimize outcome.
 
Many patients with fecal incontinence present functional defects of the internal anal sphincter or of the striated muscle with no identifiable structural defects. Some patients are amenable to repair or substitution of the sphincter. However, sacral nerve stimulation appears to offer a valid treatment option
for some of these patients.
 
Sacral nerve stimulation has long had an important therapeutic role in functional disturbances of micturition. Electrical control of urinary dysfunction began in the 1950s. Initial attempts to provoke artificial micturition involved direct stimulation of the spinal cord, the detrusor muscle, and the striated sphincter.
Currently, stimulation of the sacral nerve roots is used successfi.flly to control voiding difficulties and urinary incontinence, especially when the lower urinary tract seems to be structurally intact but functionally disturbed.
 
Recently, the experience achieved in urologic functional abnormalities with sacral nerve modulation has
been transferred to anorectal disturbances, primarily fecal incontinence. One preliminary study has reported on the effectiveness of permanent electrical stimulation of sacral spinal nerves for treatment of
fecal incontinence in three patients, with complete recovery of continence in two cases and soiling in one patient. According to Matzel et al., stimulation of the efferent motor nerves to the anal sphincters increases pressure in the anal canal by contraction of the pelvic floor and the anal sphincter muscles, Malouf et al. reported an improvement on the Wexner incontinence scale in four patients with definitive implant of a sacral electrode, the effectiveness being related to the effect on striated sphincter function and also on rectal sensation, compliance, and contractile activiVy. Tile aims of the present study were to evaluate whether permanent sacral nerve stimulation modifies symptoms of functional fecal incontinence and to evaluate the mechanisms of possible improvement.
 
DISCUSSION
The goal of sacral root stimulation is to reduce fecal incontinence. In a preliminary study, sacral nerve
stimulation was tested in three patients. According to Matzel et al., stimulation of the efferent motor
nerves to the anal sphincters increases pressure in the anal canal by contraction of the pelvic floor and the anal sphincter muscles, increasing the closing capacity. At a follow-up of six months, with a stimulation frequency of 15 Hz, Matzel el al. reported complete recovery of continence in two cases and soiling in one patient with definitive implant of a sacral electrode. Malouf et al. reported improvement on the Wexner incontinence scale from 16-20 to 3-6 in four patients with definitive implant of a sacral electrode with a stimulation frequency of 15 Hz and a follow-up of 12.5 to 25 months.
 
In our experience, electrical stimulation of sacral roots was associated with an improvement in fecal
continence. We found a significant increase in resting pressure (P < 0.05) and a slight increase in the
squeeze pressure. This may result from the extrinsic innervation of the internal anal sphincter via the sacral parasympathetic supply and from a direct effect on the striated anal sphincter.
 
Experimental work reveals an effect of low-frequency sacral nerve stimulation on the fiber typing of
the stimulated muscle, resulting in a transformation of the muscle phenotype toward fatigue-resistant fiber, similar to the phenomenon observed in dynamic graciloplasty. Sacral nerve stimulation can result in striated pelvic floor muscle contractions or in facilitation of voluntary contraction in patients with abolished or limited residual striated anal sphincter function, probably mediated by alpha motor fiber
stimulation, resulting in an increase of anal canal closing pressure. This mechanism of action, hypothesized in urologic patients by Tanagho and Schmidt in 1988, was put in doubt by Bosch and Groen in 1995 by their observation that sacral nerve stimulation at the current intensity used to achieve a curative effect in the urologic field does not activate the pelvic muscle.
 
Sacral nerve stimulation seems to have an effect on rectal sensitivity and motility, which could be of
clinical importance. Interaction between the autonomic and somatic nervous systems is an integral part
of the nerve control of the mechanisms of continence and evacuation. Functional incontinence may be-associated with reduced resting tone or reduced squeeze tone, reduced rectal sensitivity, and compliance.
 
Clinical observations suggest that stimulation-induced contraction of the pelvic floor muscles improves
perception of the anal sphincter muscles and leads to changes in functional behavior. Modulation
of sacral reflex arcs regulating rectal tone and contractility might play a potentially beneficial role in
some patients as wetl. These results with sacral nerve stimulation for fecal incontinence are similar to those obtained with sacral nerve stimulation for urinary dysfunctions.
 
Despite the fact that the precise physiologic impact of sacral nerve stimulation on the anorectal continence function is as yet undefined, permanent lowfrequency etectrostimulation of the sacral spinal
nerves represents a new therapeutic approach for the specific group of patients with no gross morphotogic defect and severe fecal incontinence. It can improve continence in this selected population by using anatomic structures and recruiting physiologic function. Given that all patients thus far diagnosed and treated have had conditions unresponsive to conservative treatment and not amenable to traditional operative therapy, an increase in our knowledge of the mechanism of action of sacral nerve stimulation and modifications of the operative technique might enable a further extension of its indications.