Detrusor acontractility in urinary retention: detrusor contractility test as exclusion criteria for sacral neurostimulation.

PURPOSE: Results of sacral neurostimulation in urinary retention are reported in the literature without distinction between the 2 functional disorders causing this condition, detrusor acontractility and functional outlet obstruction. We have suggested a stimulation test to differentiate irreversible bladder myopathy (or complete neurogenic lesion) from potential bladder contractility eligible for sacral neurostimulation.
MATERIALS AND METHODS: Direct electrostimulation of the sacral nerves was performed with the patient under general anesthesia. Urodynamic monitoring of bladder (detrusor contractility test) and bowel pressures were used. If no bladder contraction (negative detrusor contractility test) was recorded with positive somatic and bowel responses a irreversible bladder myopathy was supposed and the patient discharged home. If no bladder and no bowel contraction were recorded a complete neurogenic lesion was supposed and the patient was also discharged.
RESULTS: Of 96 patients tested with the detrusor contractility test 72 (65%) had no bladder contraction and were excluded from sacral neurostimulation therapy. In this series 15 patients had already been tested with percutaneous nerve evaluation on each S3 nerve with negative results. In 18 cases no bladder and no bowel contraction was evoked (neurogenic lesion). In the remaining 54 cases (bowel but no bladder contraction) a bladder myopathy was supposed. In 24 patients the detrusor contractility test was positive and 12 of these underwent implantation with a permanent device for sacral neurostimulation.
CONCLUSIONS: The detrusor contractility test can be considered a reliable tool to rule out detrusor acontractility due to irreversible bladder myopathy or complete neurogenic lesion from sacral neurostimulation.