Purpose: The efficacy of lumbosacral spinal cord cooling for the suppression of reflex urinary incontinence was evaluated in a rat model of cystitis-induced bladder instability.
Materials and methods: In female Sprague-Dawley rats, overactivity of the detrusor muscle was induced by inflammation of the urinary bladder. Isovolumetric intravesical pressure, urethral perfusion pressure and electromyographic (EMG) activity of the external urethral sphincter (EUS) were recorded simultaneously during repetitive local cooling (-2C or +15C) and rewarming (to 37C) of the dorsal L6/S1 spinal cord segments.
Results: Mustard oil-induced inflammation led to a marked instability of the urinary bladder without affecting urethral outlet functions. Local cooling of the dorsal lumbosacral spinal cord with temperatures of -2C as well as +15C completely abolished bladder voiding contractions in rats with an inflamed bladder as well as in non-inflamed control animals. Cooling had little effect on the EMG activity of the EUS and increased the urethral perfusion pressure. The suppression of detrusor reflex contractions was reversed within 1-7 min. after rewarming of the spinal cord.
Conclusions: Cooling of the dorsal spinal cord at the origin of the parasympathetic innervation of the bladder can be used for a reversible suppression of bladder instability without affecting the urethral outlet. Thus, local spinal cord cooling may offer a suitable method to restore continence in cases of reflex incontinence.