The effect of intravesical oxybutynin on the ice water test and on electrical perception thresholds in patients with neurogenic detrusor overactivity.
OBJECTIVE
The C-fiber-mediated bladder-cooling reflex and the determination of the current perception thresholds (CPTs) permit to investigate afferent LUT pathways. They have both been proposed to detect and differentiate neurologic bladder dysfunction. This study evaluates, prospectively, the effect of oxybutynin, an antimuscarinic with direct antispasmodic effect on smooth muscle, on repeated ice water test (IWT) and CPTs in patients with a known incomplete neurogenic bladder.


METHODS
Patients with a known incomplete lesion of the bladder innervation, detrusor overactivity during cystometric bladder filling and a continuous positive response to repeated IWT were included. After the initial tests, 30 mg intravesical oxybutynin (1 mg/ml) was instilled and left in the bladder for 15 min. Afterwards CPTs and IWT were re-assessed.


RESULTS
After the drug application, the bladder-cooling reflex could not be initiated, even after three instillations, in 16/17 patients. The bladder CPT increased from 29.7 +/- 11.3 to 39.1 +/- 15.7 mA after oxybutynin (P = 0.001). No difference was found in CPT of the left forearm (P = 0.208).


CONCLUSIONS
Intravesical oxybutynin blocks the bladder-cooling reflex and increases but does not block CPT sensation in the bladder in most patients with incomplete neurogenic lesion and detrusor overactivity. These results help explain the clinical effect of intravesical oxybutynin in neurogenic patients. They also indicate that a pharmacological local influence on C-fiber-related activity can give different clinical effects.
Faculty of Medicine, Department of Urology, University of Antwerpen, Wilrijk, Edegem, Belgium.
Tom David
TD
Van Meel
Stefan
S
De Wachter
Jean Jacques
JJ
Wyndaele
D000283:Administration, Intravesical; D000293:Adolescent; D000328:Adult; D000368:Aged; D055724:Electrophysiological Phenomena / Q000187:drug effects; D005260:Female; D006801:Humans; D007053:Ice; D008297:Male; D008333:Mandelic Acids / Q000008:administration & dosage* / Q000494:pharmacology; D008875:Middle Aged; D018727:Muscarinic Antagonists / Q000008:administration & dosage* / Q000494:pharmacology; D010465:Perception / Q000187:drug effects; D011446:Prospective Studies; D001750:Urinary Bladder, Neurogenic / Q000150:complications / Q000503:physiopathology*; D053201:Urinary Bladder, Overactive / Q000150:complications / Q000503:physiopathology*
D007053:Ice; D008333:Mandelic Acids; D018727:Muscarinic Antagonists; C005419:oxybutynin