Factors associated with somnolence during brain function mapping in awake craniotomy

Toshiyuki Mizota, Miho Hamada, Atsuko Shiraki, Takayuki Kikuchi, Yohei Mineharu, Yukihiro Yamao, Etsuko Yamamoto Hattori, Atsushi Yonezawa, Keiko Furukawa, Yoshiki Arakawa

Research output: Contribution to journalArticlepeer-review


Somnolence during brain function mapping is one of the factors that inhibit the accomplishment of the goals of awake craniotomy. We examined the effect of anesthesia depth measured by bispectral index (BIS) during pre-awake phase on somnolence during brain function mapping and also explored the factors associated with somnolence. We examined the association between BIS values during pre-awake phase and somnolence during the first 30 min of brain function mapping in 55 patients who underwent awake craniotomy at Kyoto University Hospital from 2015 to 2018. The pre-awake BIS value was defined as the mean BIS value for 60 min before the removal of the airway. Somnolence during brain function mapping was the primary outcome, defined as either of the following conditions: inability to follow up, disorientation, or inability to assess speech function. Additionally, we compared patient or perioperative variables between patients with/without somnolence. Somnolence occurred in 14 patients (25.5%), of which 6 patients (10.9%) were unable to complete brain function mapping. There was no significant difference in the pre-awake BIS value between patients with/without somnolence (median: 46 vs. 49, P = 0.192). Somnolence was not significantly associated with age, gender, and the number of preoperative anticonvulsive drugs, but patients with somnolence had a significantly lower preoperative Western Aphasia Battery (WAB) aphasia quotient score (median 93.8 vs. 98.6, P = 0.011). We did not find an association between pre-awake BIS value and somnolence during brain function mapping. Somnolence likely occurs in patients with a low preoperative WAB aphasia quotient score.

Original languageEnglish
Pages (from-to)349-353
Number of pages5
JournalJournal of Clinical Neuroscience
Publication statusPublished - 2021 Jul
Externally publishedYes


  • Awake craniotomy
  • Bispectral index
  • Somnolence
  • Western Aphasia Battery

ASJC Scopus subject areas

  • Surgery
  • Neurology
  • Clinical Neurology
  • Physiology (medical)


Dive into the research topics of 'Factors associated with somnolence during brain function mapping in awake craniotomy'. Together they form a unique fingerprint.

Cite this