Awake craniotomy

Usually employed for brain mapping, especially for speech areas. Numerous techniques and protocols have been described. Typically, the patient is temporarily anesthetized with short-acting agents (inhalational and/or injectable). This is supplemented with local anesthesia. The craniotomy is then performed and the patient is allowed to wake up while the brain is exposed to permit neurophysiologic testing during surgery. If (short-acting) paralytics are used, it is critical to reverse these agents 15–30 minutes prior to applying the electrostimulation and that a train-of-four muscle twitch can be elicited.

An awake craniotomy is a safe neurosurgical procedure that minimizes the risk of brain injury. During the course of this surgery, the patient is asked to perform motor or cognitive tasks, but some patients exhibit severe sleepiness.

For neurosurgery with an awake craniotomy, the critical issue is to set aside enough time to identify eloquent cortices by electrocortical stimulation (ECS). High gamma activity (HGA) ranging between 80 and 120 Hz on electrocorticogram (ECoG) is assumed to reflect localized cortical processing.

In recent years, there have been a number of reports on interventions in conscious patients with other neurosurgical pathologies, which may be regarded as a new emerging tendency in neurosurgery and neuroanesthesiology. Neurosurgery in conscious patients provides a special advantage because it enables highly functional neuromonitoring without use of complex devices 1).

Awake craniotomy (AC) was first performed by Sir Victor Horsley in 1886 to localise the epileptic focus with cortical electrostimulation 2).

Wilder Penfield, made mappings in conscious patients with severe epilepsy under local anaesthesia (LA) by directly observing the brain and assessing the responses to electrical stimuli. He prepared detailed reports on brain physiology, speech cortex, interpreting cortex and brain regions controlling body movements 3).

Retrospective analysis of a cohort of 17 patients with perirolandic gliomas who underwent an AC with DCS were case-control matched with 23 patients with perirolandic gliomas who underwent surgery under GA with neuromonitoring (ie, motor-evoked potentials, somatosensory-evoked potentials, phase reversal). Inpatient costs, quality-adjusted life years (QALY), extent of resection, and neurological outcome were compared between the groups.

Total inpatient expense per patient was ${\$}$ 34 804 in the AC group and ${\$}$ 46 798 in the GA group ( P = .046). QALY score for the AC group was 0.97 and 0.47 for the GA group ( P = .041). The incremental cost per QALY for the AC group was ${\$}$ 82 720 less than the GA group. Postoperative Karnofsky performance status was 91.8 in the AC group and 81.3 in the GA group (P = .047). Length of hospitalization was 4.12 days in the AC group and 7.61 days in the GA group ( P = .049).

The total inpatient costs for awake craniotomies were lower than surgery under GA. This study suggests better cost effectiveness and neurological outcome with awake craniotomies for perirolandic gliomas 4).

Lubnin AY. [Neurosurgery in conscious patients: forward to the past]. Zh Vopr Neirokhir Im N N Burdenko. 2018;82(1):93-101. doi: 10.17116/neiro201882193-101. Russian. PubMed PMID: 29543221.
Piccioni F, Fanzio M. Management of anesthesia in awake craniotomy. Minerva Anestesiol. 2008 Jul-Aug;74(7-8):393-408. PMID: 18612268.
Dziedzic T, Bernstein M. Awake craniotomy for brain tumor: indications, technique and benefits. Expert Rev Neurother. 2014 Dec;14(12):1405-15. doi: 10.1586/14737175.2014.979793. Epub 2014 Nov 21. PMID: 25413123.
Eseonu CI, Rincon-Torroella J, ReFaey K, Quiñones-Hinojosa A. The Cost of Brain Surgery: Awake vs Asleep Craniotomy for Perirolandic Region Tumors. Neurosurgery. 2017 Mar 15. doi: 10.1093/neuros/nyx022. [Epub ahead of print] PubMed PMID: 28327904.
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