 The primary objective of the study was to measure the change in bladder function as measured by Urogenital Distress Inventory UDI-6 compared to baseline over 6 months of Tysabri treatment. Secondary objectives were to i measure change from baseline over 6 months of Tysabri treatment in the number of urinary incontinence episodes per participant per week, ii measure change from baseline over 6 months of Tysabri treatment in the number of micturitions per participant per day, iii measure change in The North American Research Committee on Multiple Sclerosis NARCOMS bladderbowel subscale PSB scores from baseline over 6 months of Tysabri treatment and iv measure change in Incontinence Impact Questionnaire IIQ-7 scores from baseline over 6 months of Tysabri treatment. 