AN ANIMAL-MODEL FOR THE NEUROMODULATION OF NEUROGENIC BLADDER DYSFUNCTION

Objective To develop an animal model to examine the pathophysiology by which S3 sacral root electrostimulation alters the micturition reflex in patients with bladder hyper-reflexia. Materials and methods Chroni c sacral nerve root electrostimulation was applied to spinally transec ted rats; 21 animals were divided into four groups. The spinal cord wa s completely transected at the T10-11 level and stainless-steel electr odes implanted into the sacral foramen in 17 animals; these animals we re subsequently divided into two groups (1 and 2). Six rats in group 1 underwent sacral root electrostimulation for 2 h/day and five in grou p 2 for 6 h/day, for 21 days, The sham group (group 3, six rats) recei ved no stimulation and four rats were used as healthy controls (group 4), Voiding frequency was recorded and each animal was evaluated cysto metrically at the end of the stimulation period, The results were comp ared with the sham and control groups. Results Spinal cord transection resulted in bladder areflexia and complete urinary retention; 7-9 day s after the injury, the bladder recovered its activity. Twenty-one day s after transection all animals had evidence of uninhibited bladder co ntractions. The mean (SD) hourly frequency of urination was 0.66 (0.18 ) in healthy controls, 0.83 (0.21) in group 1.0.87 (0.34) in group 2 a nd 1.1 (0.31) in group 3. There was a significant decrease in the cyst ometric signs of bladder hyper-reflexia in groups 1 and 2 when compare d with group 3. Conclusions This work reports an initial study showing that chronic electrostimulation of sacral nerve roots can reduce the signs of bladder hyper-reflexia in the spinally injured rat, To our kn owledge, this is the first report describing the rat as an animal mode l to determine the effects of chronic electrostimulation on the mictur ition reflex.