Intradetrusor injection with botulinum toxin-type A (BTX) appears to be a highly effective new treatment for patients with intractable detrusor overactivity (DO) [1,2]. As originally described, the technique used rigid cystoscopy and therefore general anaesthesia was usually required, particularly for men. The obvious advantages of giving BTX injections as an outpatient procedure, in terms of cost, administrative logistics and reduced morbidity especially for patients with disabling neurological disease, led us to explore the possibility of injecting through a flexible cystoscope. We describe a quick, simple and safe technique for injecting BTX into the detrusor as an outpatient procedure, using only local anaesthesia.
Approval to use a BTX preparation under a Doctors and Dentists Exemption certificate (Medicine Controls Agency) was given by the Local Research Ethics Committee. Patients gave consent to treatment and were informed that the treatment was an unlicensed use of BTX, the long-term effects being unknown. Thirty-nine patients (13 men and 26 women) with intractable DO of either neurogenic or idiopathic origin, were treated using the following technique. A prophylactic antibiotic was given and 20 mL of 2% lignocaine gel (Instillagel, Farco-Pharma Gmbh, Cologne, Germany) instilled intraurethrally. The bladder was accessed using a standard flexible cystoscope (Olympus Keymed, Milton Keynes, UK) with a 2.2-mm working channel that accommodates a 27 G sheathed flexible injection needle (Olympus). The needle has a working length of 1050 mm and a needle length of 4 mm (Fig. 1a,b). BTX (200–300 units) were dissolved in 20–30 mL of 0.9% saline. According to the protocol outlined by Schurch et al., the bladder was filled to 100 mL and either 200 (for idiopathic DO) or 300 (for neurogenic DO) units of BTX administered. Twenty to 30 separate sites were injected with 1 mL each, avoiding the trigone, and the 1 mL dead space of the needle flushed with 0.9% saline. Injections were given slowly to minimize discomfort. Patients were assessed before and at 4 and 16 weeks after treatment using a voiding diary, urinary symptom questionnaire and cystometry.
ADVANTAGES AND DISADVANTAGES
The super-fine flexible injection needles that are now available make intradetrusor injection of BTX possible through a flexible cystoscope, so that the procedure can be carried out using local anaesthetic in the outpatient clinic. Patients report varying degrees of discomfort during injection (mean score of 3/10 using a visual analogue scale) but would be willing to undergo repeat injections, as and when their symptoms recur. In our experience, instilling local anaesthetic into the bladder before injection with BTX does not appear to significantly affect the pain scores and is therefore not routinely used, except in those with spinal cord injury above the level of T5, who may be prone to autonomic dysreflexia.
The issue of whether or not to inject the trigone remains unresolved. We are currently following the protocol of Schurch et al., which spares the trigone to avoid the theoretical risk of VUR, but are aware that others differ in their opinions and practice. The trigone is mainly sympathetic in its nerve supply and is thought to carry the sensations of pain and touch. Thus trigone-sparing may reduce pain during injections in awake patients. If future evidence emerges that BTX may be having a sensory effect then we will consider revising the injection sites.
All the patients treated so far have shown a marked improvement in their LUTS and urodynamic variables, with an increase in mean (sem) maximum cystometric capacity from 174 (59.9) to 580 (99.1) mL. The procedure takes < 30 min and is simple to administer in the outpatient setting. We now recommend that patients who have failed to respond to oral anticholinergic agents and are either unwilling or unsuitable to undergo reconstructive surgery be treated with intradetrusor injections of BTX via a flexible cystoscope.