LAUSR

To JNA Readers: We commend Natalini et al1 for their recent systematic review and meta-analysis of awake craniotomy procedures performed under an “asleep-awake-asleep” (SAS) technique compared with monitored anesthesia care (MAC). The findings of this review should prompt important discussion about how anesthesiologists can optimize their anesthetic technique to facilitate a thorough intraoperative neurological examination in a calm and cooperative patient in order to maximize tumor resection. It is not surprising that MAC was associated with a lower failure rate than SAS, since emergence from a deeper level of anesthesia inherently carries a higher risk of agitation and suboptimal performance on awakening. However, one anesthetic technique cannot fit all circumstances and, among other factors, the selected technique must take into consideration the environment in which the surgery takes place. This is particularly true in the context of intraoperative magnetic resonance imaging (iMRI). Whether SAS or MAC is chosen depends in part on the set-up of the magnetic resonance imaging (MRI) machine and operating suite.2 For example, the classic donut-shaped MRI prohibits any access to the patient’s airway during imaging. A full-body sterile drape is typically used to cover the patient during the scan, meaning that an awake patient may become claustrophobic while a sedated patient without a protected airway may be at risk of hypercarbia. Furthermore, varying depths of anesthesia may be needed if transporting a patient between an induction area and a separate surgical suite and MRI. The literature on the use of iMRI during awake craniotomies, although limited to small cohort studies, does suggest that iMRI results in more extensive and safer tumor resection in eloquent areas.3 As iMRI increases in popularity, anesthesiologists may have to deviate from a “conventional” awake craniotomy technique in order to adapt to the demands of this challenging setting. We look forward to seeing how future studies will reflect this shift in practice.