Sunday, November 3, 2013

FOWLER’S SYNDROME

Fowler’s Syndrome affects young women after the menarche, who develop painless retention at high bladder volumes, often following apparently unconnected precipitating events, such as minor surgery. Often, history of prior LUTS is minimal and most of the women will not report any prior urinary tract problems. It is estimated that around 40% of women affected have Polycystic Ovary Syndrome. It is important to exclude occult or undiagnosed neurological problems as a cause. The scientific explanation for the underlying sphincter problem in Fowler’s syndrome is not understood. It has been hypothesized that changes in the ion channels of the skeletal muscles of the urinary sphincter may be affected by the hormonal environment of the menarche (“hormonal channelopathy”) leading to abnormal communication directly between muscle cells (ephaptic transmission). As a consequence, the sphincter becomes overactive and hypertrophic, and reacts excessively to direct stimulation.
Diagnostic criteria include: UR of at least 1 liter on at least one occasion; exclusion of other causative factors; raised maximum urethral closure pressure on urethral pressure profilometry; increased sphincter volume on ultrasound or MRI assessment; and; a characteristic urethral sphincter EMG. Difficulties with IC can be profound—insertion of the catheter can be straightforward but then discomfort may develop, as if the sphincter were gripping the catheter, leading to consequent difficulty on catheter withdrawal. Flow rate patterns tend to be interrupted. Small volumes often are passed by micturition, leaving substantial PVR.
The most specific diagnostic test for Fowler’s Syndrome is a urethral sphincter EMG (USEMG), which differs from the pelvic floor EMG generally used for neurourological patients. In USEMG, the EMG needle is placed to one side of midline in the anterior vaginal wall, at the mid-urethral point, and advanced on to the dorsal aspect of the urethra. The neurophysiologist undertaking the test has to pay special attention to the audio signal being generated by the EMG, which confirms successful entry into the sphincter zone. The diagnostic parameter for Fowler’s Syndrome is an audio signal likened to the sound of whale noises in the ocean. Pelvic floor EMG often is non-diagnostic in this patient group.

Management of Fowler’s syndrome is specialized, and a sympathetic approach and consideration of psychological elements are essential. Strong efforts should be made to reduce the polypharmacy that many of these patients have, particularly attempting to discourage use of opiate drugs. For those patients manifesting the characteristic EMG signal who are unable to tolerate IC, the treatment of choice is sacral nerve stimulation (SNS), which can achieve normal voiding in a significant proportion of women affected. Management is difficult in patients without the characteristic EMG signal, or those patients where the SNS percutaneous needle electrode test fails to elicit a significant improvement in symptoms. Suprapubic catheter placement is generally unsatisfactory in younger women. No drug treatment has yet been established as deriving any substantive benefit. Botulinum injection into the urethral sphincter has not been tested on a systematic randomized basis. Ultimately, reconstructive surgery using a continent diversion (Mitrofanoff procedure) may be necessary.

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