The ice water test, a tool used to evaluate the function of the bladder in patients with neurological disorders, was successfully used to identify undiagnosed cases of bladder dysfunction in patients with multiple sclerosis (MS), according to researchers from Germany.
The findings of the study, “Ice water test in multiple sclerosis: a pilot trail” were published in the International Journal of Urology.
The discovery of the ice water test goes back to 1957, when two physicians first used it to evaluate the impact of neurological lesions in bladder dysfunction. The physicians instilled small amounts of ice water into the bladder by a catheter in patients with spinal cord injuries. The test was considered positive if the water was immediately expelled.
The mechanism behind bladder cooling reflex is the activation of the cold and menthol receptor 1 protein, or TRPM8, in the presence of cold stimuli. The activation of this protein provokes a spinal cord reflex and a subsequent involuntary contraction of the detrusor, the muscle covering the bladder.
Physicians found that this reflex can be provoked in children ages 5 and younger, and then disappears by maturation of the nervous system, unless a neurological condition prevents it from happening.
Now, investigators from research centers in Germany and Switzerland assessed the capacity of the ice water test to not only diagnose bladder dysfunction, but also to classify the strength of bladder contraction in MS patients.
For this purpose, researchers retrospectively analyzed 201 MS patients (141 women and 60 men) who came to the centers for urologic examinations from 2010 to 2014.
A clinically positive ice water test was defined as a detrusor contractility (Pdetmax) over 15 cm of water (cmH2O). None of the patients was taking medication targeting bladder dysfunction before the examination.
A total of 75 patients (37.3%) tested positive for the ice water test, with men showing significantly more positive tests than women (51.8% vs. 30.9%). The ice water test results were found to be correlated with incontinence episodes in patients’ sex and over 24 hours.
The test was able to unmask involuntary detrusor contraction in 16.5% of cases that were previously undiagnosed using standard medical analysis, demonstrating the improved diagnostic capacity of the test.
The team used a method called nomogram to correlate different factors affecting bladder dysfunction. The nomogram showed that the severity of bladder dysfunction can be predicted by the ice water test result, frequency of incontinence episodes, and maximum detrusor pressure (a measure of muscle function).
Interestingly, men were found to have more severe bladder dysfunction, as well as higher ice water test results, and detrusor pressure.
This retrospective study proved the capacity of the ice water test to identify bladder dysfunction in patients with MS with higher sensitivity than standard tests.
“The ice water test is a simple tool for unmasking non-identified detrusor overactivity in neurogenic bladder dysfunction,” the researchers wrote.
“A severity categorization of the detrusor overactivity can be facilitated by the use of the ice water test nomogram,” they added. “After further validation, the ice water test could be ultimately used in future as objective assessment for bladder dysfunction.”