# Anesthesia for Awake Craniotomy ## Comparison between craniotomy under general anesthesia (GA) and awake craniotomy. ![](https://i.imgur.com/7FVeSmI.jpg) ## Anesthesic methods * [PLoS One. 2016; 11(5): e0156448.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4882028/) * **SAS (asleep-awake-asleep)**: * A **total intravenous anaesthesia (TIVA)** with propofol and remifentanil or fentanyl for the first asleep phase was used in fourteen trials * Hypnotics * **Propofol**: GABAA receptors and sodium channels of the reticular formation * Hypnotic effects * Antiemetic * Antipruritic * Anticonvulsant * Bronchodilation * ↓ Intracranial pressure * No analgesic or muscle relaxant effects * Analgesic * **Remifentanil**: a potent, short-acting synthetic opioid analgesic drug * relieve pain and as an adjunct to an anaesthetic * **Fentanyl**: synthetic opioid * **Dexmedetomidine**: alpha-2 receptor agonist * sedation * anxiolytic * analgesic * vs. propofol: *shorter arousal time* after the first asleep phase and a higher degree of surgeon satisfaction. * vs. GA (general anaesthesia) * reduction of **pain induced haemodynamic reactions** to pinning and incision * less **intraoperative vasopressors and opioids** * Almost all patients undergoing SA(S) management underwent successful AC and the failure rate was minimal with 13 out of 1313 procedures (where failure rate was reported, and excluding the duplicate studies [27,44]). The meta-analysis showed a proportion of 2% [95%CI: 1–4] (Fig 2). * **MAC (monitored anaesthesia care)**: * preserving spontaneous ventilation without any airway instrumentation * RSNB (regional selective scalp nerve block) * ![](https://i.imgur.com/3t1T05g.jpg) * the used anaesthetics consisted of all possible combinations of fentanyl, remifentanil, propofol, midazolam and dexmedetomidine. * midazolam: * imidazobenzopine類衍生物，它的鎮靜作用非常快，睡眠誘導作用也非常明顯，並具有肌肉鬆弛及抗痙攣作用。 * 經過靜脈注射或肌肉注射後，在短暫的作用時間內會產生進行性的記憶喪失。 * [Anesthesic methods](https://academic.oup.com/bjaed/article/14/1/6/336124) ## Nausea/vomiting prophylaxis * Neurokinin receptor antagonist (e.g., aprepitant) * 5-HT 3 receptor antagonist (e.g., ondansetron) ## Reduce peri-tumor edema * Steroids (e.g. dexamethasone) ## Reduce the chance of perioperative seizure * Anticonvulsants (e.g., levetiracetam) ## Analgesic adjunct * NSAIDs (e.g., acetaminophen) ## Side effects of anaesthesia * May adversely affect neurocognitive function * Benzodiazepines (e.g., midazolam) * May cause nausea, itchy nose and dizziness; consider only if there is intractable pain * Opioids (e.g., fentanyl) * May cause dry mouth and emergence delirium; not recommended * Anticholinergic (e.g., atropine or scopolamine) * Possesses unwarranted neurologic effect, may cause dystonic reactions; not recommended * Metoclopramide (D2R an) * Previously used for neuroleptanalgesic anesthesia, may impede neurocognitive testing; not recommended * Droperidol (antidopamineergic) * Neuroleptanalgesic combinations consist of a potent opioid analgesic, which can abolish the perception of pain, and a neuroleptic – a tranquillizer/sedative (e.g. acepromazine or fluanisone) – that suppresses some of the undesirable side effects of the narcotic such as vomiting or excitement. ## Complications * Intraoperative seizure & neurological complications * Threatening adverse events during AC * triggered by electrical cortical stimulation * self-limited after cessation of cortical stimulation. * ice-cold saline to cortex * Anticonvulsants: small propofol bolus, thiopental or benzodiazepines * ABC (airway, breathing, circulation) * convert to GA if necessary * Discontinuation of AC was rarely necessary * [Conversion to GA between SAS (asleep-awake-asleep technique) and MAC (monitored anaesthesia care)](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4882028/) * MAC << SAS (albeit biased)