Level I and II deficits-A clinical survey on international practice of awake craniotomy and definitions of postoperative "major" and "minor" deficits

Background: Awake craniotomy (AC) is a technique that balances maximum resection and minimal postoperative deficits in patients with intracranial tumors. To aid in the comparability of functional outcomes after awake surgery, this study investigated its international practice and aimed to define categories of postoperative deficits.

Methods: A survey was distributed via neurosurgical networks in Europe (European Association of Neurosurgical Societies, EANS), the Netherlands (Nederlandse Vereniging voor Neurochirurgie, NVVN), Belgium (Belgian Society of Neurosurgery, BSN), and the United States (Congress of Neurological Surgeons, CNS) between April 2022 and April 2023. Questions involved decision-making, including patient selection, anxiety assessment, and termination of resection. Interpretation of "major" and "minor" deficits, respectively labeled "level I" and "level II," was assessed.

Results: Three hundred and ninety-five neurosurgeons from 46 countries completed the survey. Significant heterogeneity was found in the domains of indications, anxiety assessment, seizure management, and termination of resection. Moreover, the interpretation of "major" deficits mainly included language and motor impairments. Analysis across deficit categories showed significant overlap in the domains of executive function, social cognition, and vision. Secondly, "minor" deficits and "minor cognitive" deficits showed vast overlap.

Conclusions: This survey demonstrates high variability between neurosurgeons in AC practice across multiple domains, inviting international efforts to reach a consensus regarding the standardization and grading of postoperative deficits. The proposed categories of "level I" and "level II" deficits may aid in this standardization. It allows for systematic assessment of the benefit of surgery in neuro-oncology patients and allows for comparison of surgical outcomes between institutions and surgeons. This may help to optimize international guidelines for surgical neuro-oncology, including AC.