Neuro-urology – Voiding DysfunctionThe Presence of Fowler’s Syndrome Predicts Successful Long-Term Outcome of Sacral Nerve Stimulation in Women with Urinary Retention
Introduction
Sacral nerve stimulation (SNS) has proven to be an efficient treatment for chronic micturition disorders refractory to classic behavioural or pharmacologic treatment. In women with urinary retention a subset of patients can be defined by electrophysiologic studies of the external urethral sphincter. On concentric needle electromyography (EMG) of the external urethral sphincter, these patients show a specific pattern of decelerating bursts and complex repetitive discharges (CRDs) [1], [2]. This finding is referred to as Fowler’s syndrome. The underlying pathophysiology is unclear, although ephaptic spreading within the muscle bundles seems to be at the origin of the phenomenon and an association with polycystic ovaries has been suggested. An underlying channelopathy has also been suggested. Other authors question the value of CRD, since these can also be found in patients without obvious voiding problems [3]. Many treatments have been tried for women with urinary retention: urethral dilatation, intermittent catheterisation, botulinum toxin injection of the urethral sphincter, and alpha-blockers. Most of these treatments proved unsuccessful, and spontaneous recovery has not been described. SNS however has been shown to be the only efficient treatment, since it enables restoration of spontaneous voiding, which can be maintained for several years in many patients [4], [5].
Female retention patients without this specific EMG abnormality are a diagnostic challenge. In most of those patients, no underlying neurologic, metabolic, or other causal disease can be identified [5]. These women are often thought to be at risk for somatisation and conversion disorders. Although many clinical urologists might have this impression, there are no objective reasons to deny these patients the possible benefit of SNS.
Since the specific EMG abnormality is present in only a subset of women with urinary retention, the question arose as to whether this finding could form a predictive factor for long-term success of SNS.
We present a retrospective analysis of prospective data on women with urinary retention undergoing a definitive SNS implant. The predictive value of Fowler’s syndrome concerning the success rate and duration of success of SNS is assessed. The usefulness of a validated psychologic screening questionnaire in relation to long-term outcome is also evaluated.
Section snippets
Patients and methods
A consecutive series of women with nonobstructive urinary retention has been studied. Data were gathered prospectively at regular time intervals in a database containing data on urodynamics, patient satisfaction, EMG, and micturition diaries, as well as technical data on implantation and revisions. Data collection was done in a specific automated registry to comply with Belgian reimbursement regulations. The database was organised by the Belgian Health Authorities (RIZIV), and the implanted
Results
In total 62 consecutive women with urinary retention were implanted between March 1996 and November 2004. In the same period 82 women in retention underwent a PNE, leading to a 75.6% implant rate. In all patients the lead was positioned in the third sacral foramen at the right side. Thirty patients had Fowler’s syndrome; 32 had idiopathic retention. The mean age of the Fowler’s syndrome group was 49.8 ± 11.8 yr, and that of the idiopathic group was 54.1 ± 11.6 yr. The mean follow up was 43.4 ± 35.2
Discussion
For the last decade SNS has been commercially available and has proven to be a very efficient treatment for refractory micturition disorders. Despite a large worldwide experience, no good predictive factors for success have been identified.
Psychiatric comorbidity, although poorly defined, has been proposed as a negative predictive factor by some authors [8], on the basis of retrospective data. Weil et al. [8] identified 11 patients with a history of psychiatric disorders and failed SNS out of a
Conclusions
This study shows that the presence of CRDs and decelerating bursts on concentric needle EMG of the external urethral sphincter of women with nonobstructive urinary retention (Fowler’s syndrome) is a predictive factor for the success of sacral nerve stimulation. Idiopathic retention patients can benefit from SNS as well, but they have to be informed that the success rate and the duration of success might be lower than those in the Fowler’s patients. Presence of somatisation disorders or
Acknowledgements
This study was investigator driven and received only departmental funding. The implanted devices were fully reimbursed by the Belgian national health insurance (RIZIV) according to local regulations.
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