Spinal anaesthesia indirectly depresses cortical activity associated with electrical stimulation of the reticular formation

J. F. Antognini, S. L. Jinks, R. Atherley, C. Clayton, Earl Carstens

Research output: Contribution to journalArticle

37 Scopus citations

Abstract

Background. Neuraxial blockade reduces the requirements for sedation and general anaesthesia. We investigated whether lidocaine spinal anaesthesia affected cortical activity as determined by EEG desynchronization that occurs following electrical stimulation of the midbrain reticular formation (MRF). Methods. Six goats were anaesthetized with isoflurane, and cervical laminectomy performed to permit spinal application of lidocaine. The EEG was recorded before, during and after focal electrical stimulation (0.1, 0.2, 0.3 and 0.4 mA) in the MRF while keeping the isoflurane concentration constant. Results. During lidocaine spinal anaesthesia, the spectral edge frequency (SEF) after MRF electrical stimulation (13.6 (SD 1.0) Hz, averaged across all stimulus currents) was less than the SEF during control and recovery periods (18.6 (3.6) Hz and 17.2 (2.2) Hz, respectively; P<0.05). Bispectral index values were similarly affected: 69 (10) at control compared with 55 (6) during the spinal block (P<0.05). Conclusions. These results suggest that lidocaine spinal anaesthesia blocks ascending somatosensory transmission to mildly depress the excitability of reticulo-thalamo-cortical arousal mechanisms.

Original languageEnglish (US)
Pages (from-to)233-238
Number of pages6
JournalBritish Journal of Anaesthesia
Volume91
Issue number2
DOIs
StatePublished - Aug 1 2003

Keywords

  • Anaesthetic techniques, regional, subarachnoid
  • Anaesthetics local, lidocaine
  • Anaesthetics volatile, isoflurane
  • Brain, reticular formation
  • Theories of anaesthetic action, mechanisms

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine

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