Maximal bladder capacity is a positive predictor of response to desmopressin treatment in patients with MS and nocturia

Objective The aim of the study is to evaluate the efficacy of desmopressin therapy in the symptomatic treatment of nocturia in patients with multiple sclerosis (MS) and neurogenic detrusor overactivity, and to investigate the validity of maximal bladder capacity as a predictor of response to intranasal desmopressin inhalation. Material and methods A set of 20 women with MS and neurogenic detrusor overactivity enrolled in a prospective pilot study and were divided into two groups: Group A, the large bladder capacity group (maximal bladder capacity > 250 ml, compliance > 20 ml/cm H2O, n = 10) and Group B, the small bladder capacity group (maximal bladder capacity < 250 ml, compliance < 20 ml/cm H2O, n = 10). Maximal bladder capacities were measured by urodynamic evaluation. The dosage selected for the study was based on the established dose of commercially available desmopressin nasal spray (20 mu g before bedtime) and on clinical trial experience. All patients were monitored for arterial blood pressure before and after treatment and for weight increase for the first 5 days of treatment. Night time voiding diaries were maintained for the 6 weeks of the trial; similarly, serum electrolyte levels and urine osmolality were measured twice weekly during the trial. Results The mean volume of nocturnal incontinence decreased significantly in both groups (P < 0.005). The average number of episodes of nocturia per night in Group A decreased from 2.35 to 0.89 and in Group B from 2.31 to 1.65. The maximum hours of sleep uninterrupted by nocturia increased from 2.54 to 4.62 in Group A and from 2.45 to 3.23 in Group B. Side effects were infrequent; only 2 patients complained of transient headaches. Neither hyponatremia nor serum electrolyte abnormalities occurred. Conclusions Our results suggest that desmopressin is effective in the symptomatic management of nocturia in patients with MS and neurogenic detrusor overactivity. Maximal bladder capacity is a valuable predictor of response to desmopressin.