Purpose: Detrusor overactivity and urethral sphincter pseudodyssynergia may develop during recovery from cerebrovascular accidents or intracranial lesions, resulting in difficulty in urination, a large amount of residual urine, and recurrent urinary tract infection. This study evaluated the effectiveness of urethral injection of botulinum A toxin in treating these patients. Methods: Twenty-one patients with chronic cerebrovascular accidents or intracranial lesions and difficult urination were enrolled. Patients participating in the study elected to receive either 100 units of botulinum A toxin ( n = 11) or served as medically treated controls ( n = 10). The urodynamic parameters and voiding efficiency after treatment were compared between the 2 groups. Results: An excellent result was obtained in 6 patients and an improved result in 4 patients, resulting in an overall success rate of 91% in the study group. Four patients with frank urinary retention before treatment resumed spontaneous voiding. The maximal effects of botulinum A toxin appeared about 2 weeks after treatment. The voiding pressure decreased (57.8 +/- 35.2 vs. 33.8 +/- 16.9 cm H2O, p = 0.005) and the maximal flow rate increased (7.2 +/- 5.9 vs. 10.3 +/- 5.2 ml/s, p = 0.005) significantly. In the control group, 4 patients (40%) had spontaneous voiding 6 months after medical treatment, whereas 6 patients remained unchanged requiring an indwelling Foley catheter (n = 2) or clean intermittent catheterization ( n = 4). The symptom score and the quality of life index showed significantly greater improvement in the study group than in the control group. Conclusion: This study demonstrates that urethral injection of botulinum A toxin is effective and without adverse effects in the treatment of patients with urethral sphincter pseudodyssynergia after cerebrovascular accidents or the development of intracranial lesions. Copyright (C) 2004 S. Karger AG, Basel.