title: Bilateral loss of neural function after interscalene plexus blockade may be caused by epidural spread of local anesthetics: a cadaveric study.
abstract: OBJECTIVE
  Interscalene brachial plexus blockade is widely used in surgical procedures of the upper limb. Recently, we experienced the complication of a contralateral blockade after ultrasound-guided interscalene block. The clinical appearance was a blockade of both the ipsilateral and the contralateral cervical segments 6 to 8. We hypothesized that epidural spread of local anesthetics could be cause for this phenomenon.
  
  
  METHODS
  We conducted a cadaveric study using ultrasound for needle guidance of interscalene blocks in 5 cadavers by a single investigator using contrast agent. Injections were made either ventral (extrafascial) or dorsal (subfascial) to the prevertebral lamina of the deep cervical fascia. Computed tomography was obtained following each injection with contrast agent immediately after incremental injections of progressively higher volumes. Subsequently, contrast spread to anatomic landmarks was investigated by a radiologist.
  
  
  RESULTS
  After ultrasound-controlled injection of contrast agent beneath the prevertebral layer of the deep cervical fascia, 4 of the 5 investigated specimens showed contrast enhancement in the epidural space in the consecutive computed tomography scans. After extrafascial injection, none of the investigated specimens showed contrast enhancement in the epidural space.
  
  
  CONCLUSIONS
  Contralateral blockade after ultrasound-guided interscalene injection of local anesthetics is very likely to be the effect of epidural spread. Future in vivo studies are needed to understand the implications of needle location and volume on epidural spread in interscalene blockade.
authors.affiliation: Department of Anesthesiology, Perioperative Medicine and Intensive Care, Paracelsus Medical University, Salzburg, Austria. g.fritsch@salk.at
authors.forename: Gerhard
authors.initials: G
authors.lastname: Fritsch
authors.forename: Martin
authors.initials: M
authors.lastname: Hudelmaier
authors.forename: Thomas
authors.initials: T
authors.lastname: Danninger
authors.forename: Chad
authors.initials: C
authors.lastname: Brummett
authors.forename: Matthias
authors.initials: M
authors.lastname: Bock
authors.forename: Mark
authors.initials: M
authors.lastname: McCoy
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000779:Anesthetics, Local / Q000493:pharmacokinetics*; D001917:Brachial Plexus; D002102:Cadaver; D004824:Epidural Space / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000009:adverse effects* / Q000379:methods; D018084:Ultrasonography, Interventional
chemical_list: D000779:Anesthetics, Local