Page 13 - CASA Bulletin of Anesthesiologisy 2022 9(6)-1 (3)

Vol. 9, No 6, 2022

Before and after neurological testing, either IV sedatives or volatile agent may be used for
patients under GA with controlled ventilation (LMA or ETT). Inhalational anesthetics, such as
sevoflurane, has the potential to increase ICP and induce nausea and vomiting during awake
’ w either CS or AAA
approach, IV infusion of propofol solely or in combination with dexmedetomidine or
remifentanil has been used with success. Careful titration of the IV sedatives to achieve the
above-mentioned goals is the key. Optimal sedation level is one that renders a patient drowsy but
readily arousable. It takes skill and experience to achieve this balance in the complex setting of
awake craniotomies. Remifentanil may facilitate analgesia and sedation, however, risk of
11
respiratory depression is higher . Dexmedetomidine, a selective alpha 2 agonist with sedative,
anxiolytic, analgesic, sympatholytic and opioid-sparing properties, has minimal impact on
neuronal function and causes minimal respiratory depression when using a low dose, making it
particularly suitable for sedation during awake craniotomy . Although high-dose
11
dexmedetomidine may cause bradycardia, hypotension and prolonged recovery from sedation,
11
such doses are rarely required during awake craniotomy . Propofol should be discontinued at
least 15 minutes before EEG recording. Despite prompt awakening, propofol leaves a residual
EEG footprint characterized by high-frequency, high- β
abnormal activity that is being sought in the cortical surface EEG . In order to alleviate a
21
’ , ,
that very low dose of dexmedetomidine or remifentanil infusion has been maintained and titrated
to effective patient cooperation during the testing portion 22, 23 . There was a concern that adequate
cortical stimulation could not occur with ongoing sedation but studies have shown it can be used
during the testing .
24
The clinical benefits of awake craniotomy and the quality of intraoperative brain mapping
highly depend on the quality of intraoperative emergence and speech interaction with the patient
during the surgery. The sedation profile during the pre-awake phase (i.e., scalp incision, bone
flap removal, dura opening) plays a crucial role in the quality of intraoperative emergence. With
sudden movements, coughing and delirium upon emergence, patients are at risk of scalp
25
lacerations due to pin slippage, contamination of the operation field, and other injury .
Anesthetic plan should be tailored to achieve a rapid and smooth emergence and make it possible
’
successfully.

Intraoperative complications

Although very safe in experienced hands, awake craniotomy is associated with some well
11
recognized complications . In addition to those discussed previously (airway obstruction,
delirium and restlessness upon emergence, inadequate analgesia), nausea and vomiting, brain
swelling and seizures may occur during awake craniotomy . Other rarer events, such as
26
11
macroglossia and accidental intracerebral injection of local anesthetics during scalp block ,
28
27
have also been reported.
Nausea or vomiting during awake craniotomy is a serious safety concern since it may lead to
increased risk of aspiration and inadvertent brain swelling . Administration of prophylactic
12
antiemetics is advisable, especially if narcotics are administered in patients with multiple risk
factors for PONV. Using antiemetics from different pharmacological mechanisms at the

P a g e 13 | 75