title: CT-guided injection of the anterior and middle scalene muscles: technique and complications.
abstract: OBJECTIVE
  Anterior scalene block is a helpful diagnostic test for NTOS and a good predictor of surgical outcome. The purpose of this study was to describe the technique, success rate, and complications associated with CT-guided anesthetic and botulinum toxin injection of the ASM/MSM in patients with NTOS symptoms.
  
  
  METHODS
  One hundred six participants (mean age, 41.5 ± 10 years; 80 women) were identified via a retrospective review of medical records for CT-guided scalene blocks. The procedure was evaluated regarding the technical success, defined as satisfactory detection of the ASM/MSM; intramuscular needle placement; intramuscular injection of contrast; appropriate delivery of medication; and frequency of unintended BP block or other complications. We also determined the outcome of patients who underwent surgery following the block.
  
  
  RESULTS
  Study participants underwent 146 scalene injections, 83 blocks, and 63 chemodenervations, which were included in this investigation. In all cases, detection of the ASM/MSM and intramuscular needle placement was satisfactory. Postprocedural complications included 5 (3.4%) temporary BP blocks, 1 patient with (0.7%) Horner sign, 7 (4.8%) needle-induced pain reports, 1 (0.7%) case of dysphagia, and 2 (1.4%) instances of muscle weakness. There were no major complications reported. The rate of good outcome following surgery was the same in patients with positive versus negative blocks, 30/43 (70%) versus 5/7 (71%), respectively.
  
  
  CONCLUSIONS
  CT guidance is a useful adjunct in performing accurate ASM/MSM blocks with a low rate of minor complications.
authors.affiliation: Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: A
authors.initials: A
authors.lastname: Mashayekh
authors.forename: P J
authors.initials: PJ
authors.lastname: Christo
authors.forename: D M
authors.initials: DM
authors.lastname: Yousem
authors.forename: J J
authors.initials: JJ
authors.lastname: Pillai
mesh_terms: D000328:Adult; D000368:Aged; D000779:Anesthetics, Local / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D015994:Incidence; D007273:Injections, Intramuscular / Q000379:methods / Q000706:statistics & numerical data; D008297:Male; D008396:Maryland / Q000453:epidemiology; D008875:Middle Aged; D018908:Muscle Weakness / Q000453:epidemiology*; D018482:Muscle, Skeletal / Q000187:drug effects*; D009407:Nerve Block / Q000706:statistics & numerical data*; D010146:Pain / Q000453:epidemiology*; D015641:Radiography, Interventional / Q000706:statistics & numerical data*; D018570:Risk Assessment; D012307:Risk Factors; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*; D055815:Young Adult
chemical_list: D000779:Anesthetics, Local