Elevated intravesical pressures secondary to detrusor sphincter dyssynergia result in an increased risk of renal deterioration in patients with cervical and thoracic spinal cord injury, although the risk is less clear in patients with multiple sclerosis (MS). The purpose of this study was to study the impact of a closed bladder outlet on intravesical pressures in patients with MS.

The data from all patients with MS referred for urologic evaluation were prospectively entered into a urodynamic database. Patients were advised to undergo full multichannel urodynamic studies. Among the patients with detrusor overactivity, the detrusor pressures were compared between the patients with and without bladder outlet dyssynergia (BOD).

Of the 143 patients referred for evaluation and entered into the database, 127 were women. Of the 127 women, 108 completed the urodynamic studies. Overall, 62 (57%) of the 108 women had detrusor overactivity, 30 of whom had coexisting BOD. The detrusor pressures during bladder contractions were greater in patients with BOD, although not significantly. For example, the maximal detrusor pressure (49.9 ± 19.5 cm H₂O versus 43.7 ± 23.0 cm H₂O, P = 0.25) and detrusor pressure at maximal flow (37.9 ± 15.7 cm H₂O versus 33.5 ± 16.3 cm H₂O, P = 0.93) were both only slightly greater in patients with BOD.

Nonsignificant elevations in detrusor pressures were noted in patients with MS and BOD. The lack of significant elevations in detrusor pressure among the patients with MS, detrusor overactivity, and BOD could account for the relatively low incidence of upper tract damage in women with MS.