Turkish Neurosurgery
Motor evoked potentials and BIS-guided anaesthesia in image-guided mini-invasive neurosurgery of supratentorial tumors nearby the cortico-spinal tract
Roberto Cordella1, Eleonora Orena2, Francesco Acerbi 1, Elena Beretta1, Dario Caldiroli 2, Francesco DiMeco1, Carla Carozzi1
1Fondazione IRCCS Istituto Neurologico , Neurosurgery, Milan,
2Fondazione IRCCS Istituto Neurologico , Anesthesiology, Milan,
DOI: 10.5137/1019-5149.JTN.20023-17.1

Aim:to describe and evaluate the anaesthesiological regimen used in neurophysiologically monitored image-guided mini-invasive neurosurgery.Material and Methods:24 patients underwent elective surgery under general anaesthesia that was administered through Target Controlled Infusion (TCI) for effect-site concentration (Ce) of Propofol and Remifentanil, targeting Bispectral Index (BIS) in the 40-60 intervals. Stimulating intensity of transcranial motor evoked potentials (tMEP), BIS index, Propofol and Remifentanil Ce were collected at MEPs threshold (T) definition (respectively BIS@T, CeProp@T and CeRemi@T). Intraoperative seizure, explicit recall for intraoperative awareness and clinical motor status were assessed.Results:CeProp@T and CeRemi@T ranged respectively between 1.5-2.2 μg/ml (Median 1.6 μg/ml) and 3.5-18 ng/ml (Median 8 ng/ml) that were effective in keeping the BIS@T between 40 and 60 in all surgeries. tMEP thresholds ranged between 45-120mA. There was no correlation between CeProp@T, CeRemi@T and tMEP, as well as between BIS@T and respectively tMEP, CeProp@T, CeRemi@T. None of patients had neither induced electrical seizure nor explicit recalls. Motor scores were equal to preoperative in 22/24 patients.Conclusion:BIS guided general anaesthesia within a 40-60 interval, with low Ce of Propofol (≤ 2µ/ml) and high analgesic regime allows reliable tMEP measurements, avoiding post-operative neurological impairment and major adverse outcomes, such as seizure and awareness.

Corresponding author : Roberto Cordella