Rabeet Tariq1, Hafiza Fatima Aziz1, Shahier Paracha1, Noman Ahmed1, Muhammad Waqas Saeed Baqai2, Saqib Kamran Bakhshi1, Annabel McAtee3, Timothy J. Ainger4, Farhan A. Mirza4, Syed Ather Enam1
1Section of Neurosurgery, Department of Surgery, Aga Khan University Hospital, Karachi, Pakistan;
2Department of Neurosurgery, Southmead Hospital, NHS North Bristol Trust, Bristol, UK;
3University of Kentucky, College of Medicine, Karachi, Pakistan;
4Kentucky Neuroscience Institute (KNI), Department of Neurosurgery, University of Kentucky, Karachi, Pakistan
Correspondence to: Syed Ather Enam, MD, PhD, FRCSI, FRCSC, FRCSG, FACS. Section of Neurosurgery, Department of Surgery, Aga Khan University Hospital, Stadium Road, Karachi, Pakistan. Email: ather.enam@aku.edu.
Background: Awake craniotomy (AC) allows intraoperative brain mapping (ioBM) for maximum lesion resection while monitoring and preserving neurological function. Conventionally, language, visuospatial assessment, and motor functions are mapped, while assessment of executive functions (EFs) is uncommon. Impaired EF may lead to occupational, personal, and social limitations, thus, a compromised quality of life.
Methods: A comprehensive literature search was conducted through Scopus, Medline, and Cochrane Library using a pre-defined search strategy. Articles were selected after duplicates removal, initial screening, and full-text assessment. The demographic details, ioBM techniques, intraoperative tasks, and their assessments, the extent of resection (EOR), post-op EF and neurocognitive status, and feasibility and potential adverse effects of the procedure were reviewed. The correlations of tumor locations with intraoperative EF deficits were also assessed.
Results: A total of 13 studies with intraoperative EF assessment of 351 patients were reviewed. Awake-asleep-awake protocol was most commonly used. Most studies performed ioBM using bipolar stimulation, with a frequency of 60 Hz, pulse durations ranging 1–2 ms, and intensity ranging 2–6 mA. Cognitive function was monitored with the Stroop task, spatial-2 back test, line-bisection test, trail-making-task, and digit-span tests. All studies reported similar or better EOR in patients with ioBM for EF. When comparing the neuropsychological outcomes of patients with ioBM of EF to those without it, all studies reported significantly better EF preservation in ioBM groups. Most authors reported EF mapping as a feasible tool to obtain satisfactory outcomes. Adverse effects included intraoperative seizures which were easily controlled.
Conclusions: AC with ioBM of EF is a safe, effective, and feasible technique that allows satisfactory EOR and improved neurocognitive outcomes with minimal adverse effects.
Keywords: Intraoperative brain mapping (ioBM); executive functions (EFs); brain tumors; functional outcomes; cognitive outcomes
