In this randomized, double-blind clinical trial including patients with a neurogenic lower urinary tract dysfunction undergoing urodynamic investigation at the Spinal Cord Injury Center, Balgrist University Hospital, Zürich, we aim to investigate whether the detrusor contraction during the ice-water-test is provoked by the ice water or the rapid filling.

The ice-water-test (IWT) was first described 1957 by Bors and Blinn and it was thought to differentiate between lesions of the upper and lower motoneuron. In cat studies, it was shown that the IWT is a C-fiber mediated lower motoneuron segmental reflex and that these unmyelinated C fibers are associated with cold receptors. This explains the positive IWT in patients with upper motoneuron lesions. In healthy humans, the IWT is positive up to the age of 4 years and becomes negative thereafter since the reflex is centrally inhibited. However, this reflex might be unmasked by a neurological disease and/or injury.

Considering that C-fibers are involved in the pathogenesis of detrusor overactivity, the IWT seems to be a useful diagnostic tool in daily practice. However, although there are many studies published on the IWT, it is unclear whether the detrusor contraction during the IWT is provoked by the ice water or whether it might be caused by the rapid filling. Therefore, we designed this randomized, double-blind trial.

Inclusion Criteria:

• neurogenic lower urinary tract dysfunction
• urodynamic investigation
• written informed consent
• ≥ 18 years old

Exclusion Criteria:

• symptomatic urinary tract infection
• < 18 years old
• ≥ 90 years old
• no written informed consent
• pregnancy