THE INCIDENCE OF A POSITIVE ICE WATER TEST IN BLADDER OUTLET OBSTRUCTED PATIENTS - EVIDENCE FOR BLADDER NEURAL PLASTICITY

Purpose: The ice water test triggers a C fiber, capsaicin sensitive sp inal micturition reflex. We postulated that the ice water test is posi tive in a high proportion of patients with compared to those without b ladder outlet obstruction. Materials and Methods: Prospective evaluati on of 111 consecutive patients was undertaken. Symptoms of urgency, ur ge incontinence, nocturia and daytime frequency as well as the presenc e of neurological disease were obtained from history and physical exam ination. Fluorourodynamics, including ice water cystometry, and pressu re-flow studies were done for all 111 subjects. Obstruction was define d using the Abrams-Griffith nomogram and urethral resistive index. A p ositive ice water test was defined as presence of uninhibited bladder contraction with instillation of OC saline at 50 cc per minute up to a maximum of 250 cc. Detrusor instability was defined according to the International Continence Society criteria using room temperature salin e instillation. Results: When patients with neurological disease were excluded, a positive ice water test was found in 71% of subjects with bladder outlet obstruction (12 of 17), which was significantly higher (p <0.0005, Yates corrected chi-square test) than the 7% positive ice water test rate in nonobstructed subjects (3 of 44). Conversely, the i ncidence of positive detrusor instability was not statistically differ ent between the patients with or without bladder outlet obstruction. O f the subjects with neurological disease 85% (42 of 50) had a positive ice water test. The incidence of a positive ice water test was only 5 to 9% in patients with storage lower urinary tract symptoms. Conclusi ons: A positive ice water test has been previously described in infant s and individuals with neurogenic bladders. However, subjects with bla dder outlet obstruction had a significantly higher incidence of a posi tive ice water test compared to those without it, supporting the hypot hesis of an enhanced spinal micturition reflex possibly due to plastic ity of bladder afferents after bladder outlet obstruction. The ice wat er test may be useful in prognosticating bladder outlet obstruction tr eatment outcomes and determining the etiology of treatment failure.