Currently, the most commonly used mode of anaesthesia for the ambulatory intra - detrusor injection of botulinum toxin (BoNTA) is intra - vesical lidocaine solution (alkalinized or not) which is kept in the bladder for a few minutes (from 15 to 20) while the patient is making postural changes. However, many other cystoscopic procedures are performed under intra - urethral lidocaine gel, which provides a good anaesthesia. We aim to assess the anaesthetic efficacy of two different modalities of anaesthesia for the injection of BoNTA: intra - vesical lidocaine solution compared to the intra - urethral lidocaine gel.

In order to achieve our objective, we carried out in our hospital a comparative study between September 2017 and January 2019 about pain, tolerability and complications of 45 patients (all women) who underwent the ambulatory BoNTA injection with flexible cystoscope and a 4mm length and 0’4mm calibre needle under intra - urethral lidocaine gel (group 1, n = 23 women) or alkalinized lidocaine solution (group 2, n = 22 women). We evaluated pain and procedure tolerability, assessed with the visual analogue pain scale score (VAS), immediately at the end of the procedure and before the discharge. We analysed too other variables such as the duration of the procedure, time to discharge, and adverse effects attributable to the local anesthetic and the procedure itself. Data were processed using SPSS 20 for Windows.

We did not find statistically significant differences between both groups in the analysed variables: mean VAS score referred to the procedure (2,09 group 1 vs 2,23 group 2) and mean VAS at the moment of the discharge (0 vs 0), mean duration of the procedure (8min vs 7,5min), time to the discharge (22min vs 20,5min), and the presence of adverse effects of the procedure (30,5% vs 36,4%). However, it was statistically significant different (p<0.05) the percentage of adverse effects related to the anaesthesia: 40,9% of women in group 2 referred any of these adverse effect (dysuria and fatigue) in contrast to 13% in group 1 (figure / table 1).

Both groups showed similar results in terms of pain, tolerability and complications of the procedure. However, the main advantages of the intra - urethral lidocaine gel are avoiding systemic effects of the lidocaine solution (with a significant and clinically relevant decrease in the percentage of adverse effects in the group 1 13% vs 40,9%) and decreasing the total duration of the procedure as well as you do not have to wait with the lidocaine solution inside the bladder. The main complications of the procedure we found were haematuria and urinary tract infections. All these data are similar to other referred for autors in the literature (see references).

The key points that allow us to perform the procedure with this anesthetic protocol were: 1) Changing the operating room for our Urodynamics Unit, 2) Changing the rigid cystoscope for the flexible and 3) Changing our needle for a thiner (0,4mm) and shorter (4mm) one. All these aspects made the feelings and experiences of our patients more comfortable.

So, taking all the points in to consideration, we have recently change our diary clinical practice. Now, we perform the injection of botulinum toxine only under intra - urethral lidocaine gel. But, we have to be cautious and keep analysing our patients' experiencie and feelings to offer them the best anaesthesia available.

Intra - detrusor injection of botulinum toxin can be performed safety and ambulatory, with intra - urethral lidocaine gel as anaesthesia with less systemic effects of the anaesthesia and without an increase of pain or complications compared to the alkalinized lidocaine solution group.

Nambiar, A. K., Younis, A., Khan, Z. A., Hildrup, I., Emery, S. J., & Lucas, M. G. (2016). Alkalinized lidocaine versus lidocaine gel as local anesthesia prior to intra-vesical botulinum toxin (BoNTA) injections: A prospective, single center, randomized, double-blind, parallel group trial of efficacy and morbidity. Neurourology and Urodynamics, 35(4), 522–527. http://doi.org/10.1002/nau.22750.
Aaronson, D. S., Walsh, T. J., Smith, J. F., Davies, B. J., Hsieh, M. H., & Konety, B. R. (2009). Meta-analysis: does lidocaine gel before flexible cystoscopy provide pain relief? BJU International, 104(4), 506–510. http://doi.org/10.1111/j.1464-410X.2009.08417.x.