The efficacy of botulinum toxin injection to the external urethral sphincter for detrusor external sphincter dyssynergia

Purpose: Botulinum toxin (BTX) acts by inhibiting acetylcholine (ACh) release at the presynaptic cholinergic neuromuscular junction, and is applied in various urethral and bladder dysfunctions, including detrusor external sphincter dyssynergia (DESD). We investigated the use of BTX in DESD patients as a reversible chemical sphincterotomy. Materials and methods: A total of 6 patients (male 3, female 3) with DESD were included. Their mean age was 45.5 years. The underlying diseases were multiple sclerosis (1), meningomyelocele (1), spinal cord injury (1), multiple systemic atrophy (1) and transverse myelitis (2). All the patients had severe voiding symptoms and large residual urine, despite anticholinergics and α-adrenoceptor antagonists with clean intermittent catheterization (CIC). Urodynamic studies were performed before and 1 month after treatment. A total of 100 units of BTX-A (Botox®) were injected at 4 sites, 3, 6, 9 and 12 o'clock relative to the external sphincter, under anesthesia, on an outpatient basis. The α-adrenoceptor antagonist medication was discontinued for evaluation after surgery. Results: At 1 month after the injection, the mean maximal flow rate was increased (from 8.4 to 12.2ml/sec) and mean residual urine was decreased (from 258 to 120ml) compared to the baseline values. The external sphincter pressure was decreased. All patients were able to discontinue the CIC. There were no systemic complications, such as respiratory distress or myasthenic crisis. Conclusions: Transurethral BTX-A injections were safe and effective for releasing or ameliorating a lower urinary tract obstruction due to DESD, and a safe and valuable therapeutic option in DESD patients not desiring surgery or CIC, and who are resistant to medications.