title: A morphological evaluation of botulinum neurotoxin A injections into the detrusor muscle using magnetic resonance imaging.
abstract: OBJECTIVE
  Although botulinum neurotoxin type A (BoNT/A) intradetrusor injections are a recommended therapy for neurogenic detrusor overactivity (NDO), refractory to antimuscarinic drugs, a standardisation of injection technique is missing. Furthermore, some basic questions are still unanswered, as where the toxin solution exactly spreads after injection. Therefore, we investigated the distribution of the toxin solution after injection into the bladder wall, using magnet resonance imaging (MRI).
  
  
  METHODS
  Six patients with NDO were recruited. Three of six patients received 300 U of BoNT/A + contrast agent distributed over 30 injection sites (group 1). The other three patients received 300 U of BoNT/A + contrast agent distributed over 10 injection sites (group 2). Immediately after injection, MRI of the pelvis was performed. The volume of the detrusor and the total volume of contrast medium inside and outside the bladder wall were calculated.
  
  
  RESULTS
  In all patients, a small volume (mean 17.6%) was found at the lateral aspects of the bladder dome in the extraperitoneal fat tissue, whereas 82.4% of the injected volume reached the target area (detrusor). In both groups there was a similar distribution of the contrast medium in the target area. A mean of 33.3 and 25.3% of the total detrusor volume was covered in group 1 and 2, respectively. Six weeks after injection, five of six patients were continent and showed no detrusor overactivity in the urodynamic follow-up. No systemic side effects were observed.
  
  
  CONCLUSIONS
  Our results provide morphological arguments that the currently used injection techniques are appropriate and safe.
authors.affiliation: Neurourology, Spinal Cord Injury Center, Balgrist University Hospital, Forchstrasse 340, Zurich 8008, Switzerland. ulrich.mehnert@paralab.balgrist.ch
authors.forename: Ulrich
authors.initials: U
authors.lastname: Mehnert
authors.forename: Sönke
authors.initials: S
authors.lastname: Boy
authors.forename: Marius
authors.initials: M
authors.lastname: Schmid
authors.forename: André
authors.initials: A
authors.lastname: Reitz
authors.forename: Alexander
authors.initials: A
authors.lastname: von Hessling
authors.forename: Juerg
authors.initials: J
authors.lastname: Hodler
authors.forename: Brigitte
authors.initials: B
authors.lastname: Schurch
mesh_terms: D000283:Administration, Intravesical; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage* / Q000493:pharmacokinetics; D006801:Humans; D007273:Injections, Intramuscular; D008279:Magnetic Resonance Imaging; D009498:Neurotoxins / Q000008:administration & dosage* / Q000493:pharmacokinetics; D014018:Tissue Distribution; D001743:Urinary Bladder / Q000473:pathology*; D001750:Urinary Bladder, Neurogenic / Q000188:drug therapy* / Q000473:pathology*
chemical_list: D009498:Neurotoxins; D019274:Botulinum Toxins, Type A