====== Awake craniotomy anesthesia ====== ===== Preoperative evaluation ===== The patient should be evaluated in the [[anesthesia]] clinic for [[awake craniotomy]] ((Eseonu CI, ReFaey K, Garcia O, John A, Quiñones-Hinojosa A, Tripathi P. Awake Craniotomy Anesthesia: A Comparison of the Monitored Anesthesia Care and Asleep-Awake-Asleep Techniques. World Neurosurg. 2017 Aug;104:679-686. doi: 10.1016/j.wneu.2017.05.053. Epub 2017 May 19. PMID: 28532922.)). History should be obtained, and anaesthesiological examination should be performed in all patients before anaesthesia. In addition to physiological evaluation, psychiatric evaluation should also be performed to serve as a guide for patient selection. Airway evaluation is especially important ((Piccioni F, Fanzio M. Management of anesthesia in awake craniotomy. Minerva Anestesiol. 2008 Jul-Aug;74(7-8):393-408. PMID: 18612268.)). ((Venkatraghavan L, Pasternak JJ, Crowley M. Anesthesia for awake craniotomy. Up To Date. 2017;20:11. Available from: www.uptodate.com.)). ===== Patient selection ===== The criteria for patient selection vary according to surgeons and institutions. In some institutions, absolute contraindications to AC are unwillingness of the patient and claustrophobia. Relative contraindications include conditions that increase the risk of sedation failure, prevent the cooperative effort required for the test or introduce a risk to the airway. Contraindications are anxiety disorders, apparent dysphagia, confusion or somnolence, alcohol or drug dependence, chronic pain disorders, restless legs syndrome, low pain tolerance, morbid obesity, obstructive sleep apnoea, expected difficult airway and uncontrolled cough. It is not performed in cases, such as vascular tumours and tumours close to the cerebral venous sinuses, in which a high volume of blood loss is expected (>750 mL-1000 mL) ((Venkatraghavan L, Pasternak JJ, Crowley M. Anesthesia for awake craniotomy. Up To Date. 2017;20:11. Available from: www.uptodate.com.)) ---- 1. in the pre-op holding area, load with Precedex® ([[dexmedetomidine]]) 0.5 mcg/kg IV over 20 minutes followed by intra-op infusion at 0.4–1.0 mcg/kg/hr 2. induction of anesthesia utilizes [[propofol]] 3 mg/kg IV followed by laryngeal mask airway (LMA) placement 3. skull block: injection of local anesthetic (e.g. 30 ml of 0.5% bupivacaine) to permit the skin incision and also rigid head fixation with pins (as required for image navigation devices, and situations where no head movement can be tolerated during surgery) without pain at the time of the wake-up. Injection at 4 regions on each side ❶ supraorbital & supratrochlear nerves: 2 ml injected 1.5 cm above the supraorbital foramen above the medial third of the orbit. NB: if you are going to use surface matching to register the patient for image guidance (e.g. BrainLab or Stealth), injecting here may deform the skin and affect the registration accuracy. Consider injecting a lower volume of higher concentration agent (e.g. 2% lidocaine) ❷ auriculotemporal nerve: 5 ml injected 1.5 cm anterior to the tragus. ✖ Caution: to avoid anesthetizing the facial nerve, inject just deep to the subcutaneous tissue ❸ postauricular branches of the greater auricular nerve: 2 ml 1.5 cm posterior to the antitragus ❹ greater, lesser & third occipital nerves: inject 5 ml with a 22 gauge spinal needle at the mastoid process and proceed along the nuchal ridge until the midline is reached 4. start inhalational anesthesia with 0.5 MAC desflurane with the patient breathing spontaneously while the scalp incision, craniotomy, and dural opening are performed (the dura is pain sensitive, the brain is not) 5. as the dural opening is begun, the desflurane is turned off and a remifentanil infusion of 0.1–0.2 mcg/kg/min IV is started 6. by the time the dural opening is completed, the desflurane has usually worn off and the LMA can be removed 7. remifentanil is then titrated for pain control 8. neurophysiologic testing can usually be performed at this time 9. the operation may often be carried to completion with the patient awake, although once the intracranial part of the operation is completed, more pain relief may be desired and general anesthesia may be needed for pain control or agitation (LMA may suffice here) ---- ====Management of anesthesia==== The importance of minimizing pain and preparing patients thoroughly to reduce anxiety and maximize cooperation. Awake surgery is an excellent treatment modality for brain tumors with very positive perception by patients ((Beez T, Boge K, Wager M, Whittle I, Fontaine D, Spena G, Braun S, Szelényi A, Bello L, Duffau H, Sabel M; European Low-grade glioma Network. Tolerance of awake surgery for glioma: a prospective European Low-grade glioma Network multicenter study. Acta Neurochir (Wien). 2013 Jul;155(7):1301-8. doi: 10.1007/s00701-013-1759-0. Epub 2013 May 21. PubMed PMID: 23689968. )). Different anesthetic combinations, including neurolept, [[propofol]] with or without opioid infusions, and asleep-awake-asleep techniques, have been reported for awake craniotomy. In all these techniques, respiratory depression has been reported as a complication. see [[dexmedetomidine]] Different protocols exist for anesthetic care during awake craniotomy based on monitored anesthesia care (MAC) or general anesthesia (asleep-awake-asleep technique). Nevertheless the administration of anesthetics, expectedly, is not without drawbacks, side effects and risks. A new approach for awake craniotomies emphasizes the need of adequate communication with patients ((Hansen E, Seemann M, Zech N, Doenitz C, Luerding R, Brawanski A. Awake craniotomies without any sedation: The awake-awake-awake technique. Acta Neurochir (Wien) 2013;155:1417–24.)). [[Scalp block]] see http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4236942/#ref11 Awake [[surgery]] with [[intraoperative brain mapping]] is highly recommended for patients with [[diffuse Low-grade glioma]]s in [[language area]]s, to maximise the [[extent of resection]] while preserving the integrity of functional networks and thus [[quality of life]]. The picture naming test [[DO 80]] is the gold standard for language assessment before, during, and after surgery. [[Cognitive function]]ing is correlated with quality of life, itself linked with return to work. The objective was to evaluate the significance of measuring naming speed, and its correlation with the return to professional activities. Two complementary studies are reported. In the first retrospective study, eleven patients were examined post-operatively. Five patients were selected because they were not able to resume their professional activities ("no return group 1"). They were compared with a control group of six patients who are working normally after surgery ("return group 1"). The eleven patients performed a global language and neuropsychological assessment, with a post-operative median follow-up of 35 months. In a subsequent prospective study, twelve patients were examined pre-operatively and post-operatively. Six patients who were not able to return to work ("no return group 2") were compared with a control group of six patients who were working normally after the surgery ("return group 2"). The twelve patients performed a pre and post-operative language assessment, with a median follow-up of 9 months. Our results show, for the first time, that naming speed is significantly correlated with a major criterion of quality of life: the return to professional activities. There were no differences between the two groups regarding other measures of cognition. Assessing naming times, and not only naming accuracy, is essential in the management of low-grade glioma patients, before, during, and after surgery, to preserve their quality of life by resuming their previous professional activity. Our results have fundamental implications concerning the comprehension of language processing and its relationship with cognitive functioning ((Moritz-Gasser S, Herbet G, Maldonado IL, Duffau H. Lexical access speed is significantly correlated with the return to professional activities after awake surgery for low-grade gliomas. J Neurooncol. 2012 May;107(3):633-41. doi: 10.1007/s11060-011-0789-9. Epub 2012 Jan 24. PubMed PMID: 22270847.)). ===== Case reports ===== Two cases of awake craniotomy with [[Monitored anesthesia care]] (MAC) using [[high flow nasal cannula]] (HFNC) and [[oxygen reserve index]] (ORi). Gook et al. adjusted the fraction of inspired [[oxygen]] of the HFNC according to the ORi level. The patient underwent successful awake craniotomy without a [[desaturation]] event or additional [[airway]] intervention. Combined HFNC and ORi monitoring may provide adequate oxygen reserves in patients undergoing awake craniotomy ((Gook J, Kwon JH, Kim K, Choi JW, Chung IS, Lee J. Awake craniotomy using a high-flow nasal cannula with oxygen reserve index monitoring - A report of two cases. Anesth Pain Med (Seoul). 2021 Oct;16(4):338-343. doi: 10.17085/apm.21022. Epub 2021 Oct 29. PMID: 35139614.)) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6101712/#:~:text=Providing%20anaesthesia%20for%20awake%20craniotomy,are%20used%20as%20sedative%20agents.