title: The potential of quantified lower cranial nerve EMG for monitoring of anesthetic depth.
abstract: BACKGROUND
  During surgery, lower cranial nerve (CN) electromyography (EMG) may show spontaneous activity without surgical correlate. These episodes have been observed in association with sudden patient movement. In the study presented, this activity was quantified and correlated to the Bispectral Index (BIS) to evaluate the potential of lower CN-EMG for monitoring the depth of anesthesia.
  
  
  METHODS
  Spontaneous EMG activity in muscles targeted by the CNs IX, X, and XII was quantified and correlated with the BIS measured in 23 patients operated on for posterior fossa pathology. In a blinded retrospective analysis, the time interval from beginning of build-up of the respective parameter (EMG activity and BIS) until extubation was marked. The resulting time intervals were then compared between BIS and EMG.
  
  
  RESULTS
  EMG and BIS build-up was seen 12.3 and 5.9 minutes, respectively, before extubation in median. Thus, EMG provided a longer "warning time" (P=0.026). Isolated lower CN EMG channels preceded BIS in 53%, 62%, and 70% (CN IX, X, and XII). The earliest available EMG channel preceded BIS in 67% of the patients by a median time of 4.3 minutes. The beginning of EMG build-up in the earliest channel was found to be significantly earlier than BIS (P<0.001).
  
  
  CONCLUSIONS
  Spontaneous EMG of muscles targeted by lower CNs seems to correlate well with arousal reactions at the end of anesthesia. In many cases, this effect preceded BIS changes. Thus, lower CN EMG monitoring may be a valuable tool in monitoring adequate depth of anesthesia.
authors: Department of Neurosurgery, University of Halle, Halle, Germany. julian.prell@medizin.uni-halle.de
authors: Julian
authors: J
authors: Prell
authors: Stefan
authors: S
authors: Rampp
authors: Jana
authors: J
authors: Ache
authors: Sven
authors: S
authors: Laule
authors: Jens
authors: J
authors: Rachinger
authors: Christian
authors: C
authors: Scheller
authors: Alex
authors: A
authors: Alfieri
authors: Christian
authors: C
authors: Strauss
mesh_terms: D000328:Adult; D000368:Aged; D000762:Anesthesia Recovery Period; D018686:Anesthetics, Intravenous; D003243:Consciousness / Q000187:drug effects*; D003391:Cranial Nerves / Q000187:drug effects*; D004569:Electroencephalography / Q000379:methods; D004576:Electromyography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D015588:Observer Variation; D010880:Piperidines; D015742:Propofol; D000077208:Remifentanil; D012189:Retrospective Studies; D016037:Single-Blind Method; D055815:Young Adult
chemical_list: D018686:Anesthetics, Intravenous; D010880:Piperidines; D000077208:Remifentanil; D015742:Propofol