Page 14 - CASA Bulletin of Anesthesiologisy 2022 9(6)-1 (3)

CASA Bulletin of Anesthesiology

beginning of the procedure may help achieve optimal outcome. Other measures may include
gentle manipulation of the dura and limitation of narcotic usage .
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Although spontaneous ventilation may assist in keeping the brain relaxed due to maintenance
of negative intrathoracic pressure and promotion of cerebral venous outflow, spontaneous
ventilation under sedation may pose the problem of brain swelling due to hypercapnia resulting
from decreased respiratory effort and airway obstruction . There are a few maneuvers that may
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improve the conditions , including elevating the head, decreasing sedation to improve
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respiration and use of mannitol or furosemide. One should keep in mind that inserting
nasopharyngeal or oropharyngeal airway or applying jaw thrust to improve respiration may
trigger patient movement, coughing and straining leading to worsening brain swelling. If there is
’ , A w ETT or
LMA to initiate hyperventilation.

During electrical cortical stimulation, an anesthesiologist should be prepared to treat grand
mal seizures. The main risk factors for intraoperative seizures are history of preoperative seizures
and frontal lobe tumors , although preoperative antiepileptic medication prophylaxis did not
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show benefits of seizures prevention in brain tumor resection . Seizures usually stop with
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cessation of cortical stimulation or with irrigation of the cortex with cold saline. When seizures
are not self-limited, pharmacologic intervention (e.g., with propofol in increments of 0.5-1.0
mg/kg) may be warranted. However, propofol should be withheld briefly until it is clear that the
seizure is not going to terminate spontaneously because it may interfere with subsequent EEG
localization for a while . Other anticonvulsants, such as benzodiazepam, may not be optimal
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due to slower clearance and possible interference with further functional testing. Postictal
drowsiness, respiratory depression, and hypotension may occur. Be prepared to convert to GA
and secure the airway with ETT or LMA if necessary.

Conclusion

Appropriate patient selection and preparation are crucial to the procedural success. Every
effort should be made to alleviate a p ’
tolerance of the procedure. Regardless of the chosen anesthetic approach, the goal is to achieve
hemodynamic stability, adequate brain relaxation, and rapid and smooth emergence for
neurological testing. A comprehensive plan for supporting or securing the airway emergently
should be in place. Anesthesia providers should be prepared to treat intraoperative complications
including brain swelling and seizures during awake craniotomy. Strategic anesthetic planning
tailored to each individual patient and a skilled multidisciplinary team are essential for the
success of awake craniotomy.

References

1. Kulikov A, Lubnin A. Anesthesia for awake craniotomy. Curr Opin Anaesthesiol. 2018 Oct;31(5): 506-510.
2. Spena G, Garbossa D, Panciani PP, et al. Purely subcortical tumors in eloquent areas: awake surgery and cortical and
subcortical electrical stimulation (CSES) ensure safe and effective surgery. Clin Neurol Neurosurg. 2013; 115(9):1595–
1601.

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