Turkish Neurosurgery 2018 , Vol 28 , Num 3
Motor Evoked Potentials and Bispectral Index-Guided Anaesthesia in Image-Guided Mini-Invasive Neurosurgery of Supratentorial Tumors Nearby the Cortico-Spinal Tract
Roberto CORDELLA1,Eleonora ORENA2, Francesco ACERBI1,Elena BERETTA1,Dario CALDIROLI2,Francesco DIMECO1, Carla CAROZZI2
1Fondazione IRCCS Istituto Neurologico C. Besta, Department of Neurosurgery, Milan, Italy
2Fondazione IRCCS Istituto Neurologico C. Besta, Department of Anaesthesia, Milan, Italy
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: Twenty-four 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 the Bispectral Index (BIS) in the 40-60 intervals. The stimulating intensity of transcranial motor evoked potentials (tMEP), BIS, 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 ?g/ml (Median 1.6 ?g/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 and 120 mA. 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 induced electrical seizure or explicit recalls. Motor scores were equal to preoperative values in 22/24 patients.

CONCLUSION: BIS-guided general anaesthesia within a 40-60 interval, with low Ce of Propofol (?2 ?/ml) and high analgesic regime allow reliable tMEP measurements, avoiding postoperative neurological impairment and major adverse outcomes, such as seizure and awareness. Keywords : Bispectral index, Brain motor area, Motor evoked potentials, Propofol, Remifentanil

Corresponding author : Roberto CORDELLA, roberto.cordella@istituto-besta.it