title: MRI of axillary brachial plexus blocks: a randomised controlled study.
abstract: BACKGROUND
  Axillary plexus blocks are usually guided by ultrasound, but alternative methods may be used when ultrasound equipment is lacking. For a nonultrasound-guided axillary block, the need for three injections has been questioned.
  
  
  OBJECTIVE
  Could differences in block success between single, double and triple deposits methods be explained by differences in local anaesthetic distribution as observed by MRI?
  
  
  METHODS
  A blinded and randomised controlled study.
  
  
  METHODS
  Conducted at Oslo University Hospital, Rikshospitalet, Norway from 2009 to 2011.
  
  
  METHODS
  Forty-five ASA 1 to 2 patients scheduled for surgery were randomised to three equally sized groups. All patients completed the study.
  
  
  METHODS
  Patients in the single-deposit group had an injection through a catheter parallel to the median nerve. In the double-deposit group the patients received a transarterial block. In the triple-deposit group the injections of the two other groups were combined. Upon completion of local anaesthetic injection the patients were scanned by MRI, before clinical block assessment. The distribution of local anaesthetic was scored by its closeness to terminal nerves and cords of the brachial plexus, as seen by MRI. The clinical effect was scored by the degree of sensory block in terminal nerve innervation areas.
  
  
  METHODS
  Sensory block effect and MRI distribution pattern.
  
  
  RESULTS
  The triple-deposit method had a higher success rate (100%) than the single-deposit method (67%) and the double-deposit method (67%) in blocking all cutaneous nerves distal to the elbow (P = 0.04). The patients in the triple-deposit group most often had the best MRI scores. For any nerve or cord, at least one of the single-deposit or double-deposit groups had a similarly high MRI score as the triple-deposit group.
  
  
  CONCLUSIONS
  Distal to the elbow, the triple-deposit method had the highest sensory block success rate. This could be explained to some extent by analysis of the magnetic resonance images.
  
  
  BACKGROUND
  ClinicalTrials.gov identifier: NCT01033006.
authors: From the Department of Anaesthesiology, Diakonhjemmet Hospital (TK), The Intervention Centre, Oslo University Hospital, Rikshospitalet, Oslo (TK, PKH, FC), Department of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo (HJS), Department of Orthopaedics, Oslo University Hospital, Rikshospitalet, Oslo (MR), Department of Anaesthesiology, University Hospital of North Norway and Institute of Clinical Medicine, University of Tromsø, Tromsø (ØK) and Institute of Clinical Medicine, University of Oslo, Oslo, Norway (HJS, MR).
authors: Trygve
authors: T
authors: Kjelstrup
authors: Per K
authors: PK
authors: Hol
authors: Frédéric
authors: F
authors: Courivaud
authors: Hans-Jørgen
authors: HJ
authors: Smith
authors: Magne
authors: M
authors: Røkkum
authors: Øivind
authors: Ø
authors: Klaastad
mesh_terms: D000328:Adult; D000368:Aged; D000779:Anesthetics, Local / Q000008:administration & dosage*; D001365:Axilla; D065527:Brachial Plexus Block / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D016037:Single-Blind Method
chemical_list: D000779:Anesthetics, Local