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 spinal micturition reflex. We postulated that the ice water test is positive in a high proportion of patients with compared to those without bladder outlet obstruction.

MATERIALS AND METHODS

Prospective evaluation of 111 consecutive patients was undertaken. Symptoms of urgency, urge incontinence, nocturia and daytime frequency as well as the presence of neurological disease were obtained from history and physical examination. Fluorourodynamics, including ice water cystometry, and pressure-flow studies were done for all 111 subjects. Obstruction was defined using the Abrams-Griffith nomogram and urethral resistive index. A positive ice water test was defined as presence of uninhibited bladder contraction with instillation of 0C 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 saline 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 incidence of positive detrusor instability was not statistically different between the patients with or without bladder outlet obstruction. Of 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.

CONCLUSIONS

A positive ice water test has been previously described in infants and individuals with neurogenic bladders. However, subjects with bladder outlet obstruction had a significantly higher incidence of a positive ice water test compared to those without it, supporting the hypothesis of an enhanced spinal micturition reflex possibly due to plasticity of bladder afferents after bladder outlet obstruction. The ice water test may be useful in prognosticating bladder outlet obstruction treatment outcomes and determining the etiology of treatment failure.