Factors associated with somnolence during brain function mapping in awake craniotomy
Toshiyuki Mizota1, Miho Hamada1, Atsuko Shiraki1
1Department of Anesthesia, Kyoto University Hospital, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
Summary
Anesthesia depth, measured by bispectral index (BIS), did not predict somnolence during awake craniotomy brain mapping. Patients with lower preoperative Western Aphasia Battery scores were more likely to experience somnolence.
Area of Science:
- Neurosurgery
- Anesthesiology
- Neuroscience
Background:
- Somnolence during awake craniotomy brain mapping can impede surgical goals.
- Anesthesia depth monitoring is crucial for optimizing patient states during these procedures.
Purpose of the Study:
- To investigate the impact of anesthesia depth, using bispectral index (BIS), during the pre-awake phase on somnolence during brain function mapping.
- To identify patient and perioperative factors associated with somnolence during awake craniotomy.
Main Methods:
- A retrospective study of 55 patients undergoing awake craniotomy between 2015-2018.
- Anesthesia depth was assessed using the mean BIS value for 60 minutes before airway removal (pre-awake BIS).
- Somnolence was defined as inability to follow up, disorientation, or impaired speech assessment during mapping.
Main Results:
- Somnolence occurred in 25.5% of patients, with 10.9% unable to complete brain mapping.
- No significant difference in pre-awake BIS values was found between patients with and without somnolence.
- Lower preoperative Western Aphasia Battery (WAB) aphasia quotient scores were significantly associated with somnolence.
Conclusions:
- Pre-awake BIS values do not reliably predict somnolence during brain function mapping in awake craniotomy.
- Somnolence during awake craniotomy appears more likely in patients with lower preoperative WAB aphasia quotient scores.
- Further research may explore strategies to mitigate somnolence in at-risk patient populations.
