We read with interest the article ‘Intradetrusor versus suburothelial onabotulinum toxin A injections for neurogenic detrusor overactivity: a pilot study’ published in Spinal Cord by Krhut et al.1 The authors need to be commended for undertaking one of the first randomized controlled studies to compare intradetrusor versus suburothelial injections of onabotulinum toxin A. We have a few comments regarding this study.
The authors describe using International Units (IU) of onabotulinum toxin. We understand that onabotulinum toxin is not dispensed in IU; rather it is marketed as Allergan Units (U) (http://www.medicines.org.uk/EMC/medicine/112/SPC/BOTOX+100+Units/). A review article in European Urology also uses U when discussing dosage.2 We feel that U rather than IU should be used for the purpose of standardization.
The authors also describe the injection technique very well using ultrasound measurement of bladder wall thickness. While there is evidence to suggest extravesical spread in association with botulinum toxin injections, we feel that in practice it is very difficult be certain clinically that all injections have been undertaken into the detrusor or suburothelially. Consequently, it is difficult to base the results on this variation. Indeed, due to this uncertainty, this aspect was not commented upon in the recent review by Mangera et al.2
Finally, we are not sure why the authors recommend suburothelial injections when they conclude that the results are not different between the two groups and that there is better detrusor compliance in the intradetrusor group.
Krhut J, Samal V, Nemec D, Zvara P . Intradetrusor versus suburothelial onabotulinumtoxinA injections for neurogenic detrusor overactivity: a pilot study. Spinal Cord 2012; 50: 904–907.
Mangera A, Andersson KE, Apostolidis A, Chapple C, Dasgupta P, Giannantoni A et al. Contemporary management of lower urinary tract disease with botulinum toxin A: a systematic review of botox (onabotulinumtoxinA) and dysport (abobotulinumtoxinA). Eur Urol 2011; 60: 784–795.
First author declares no conflict of interest. The second author has been a consultant for Allergan and an invited lecturer for Pfizer, Astellas and Wellspect Healthcare (formerly Astra Tech).
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Burki, J., Hamid, R. Onabotulinum toxin injection in neurogenic detrusor overactivity: intradetrusor versus suburothelial. Spinal Cord 51, 725 (2013). https://doi.org/10.1038/sc.2013.62