# Mapping High-Level Evidence in Neuroanesthesia: A Scoping Review of Multicenter Randomized Controlled Trials in Anesthesia for Neurosurgery

## TL;DR

This review maps multicenter trials in neuroanesthesia, finding limited high-quality evidence and a focus on short-term outcomes.

## Contribution

The study provides a comprehensive map of multicenter RCTs in neuroanesthesia, highlighting gaps in evidence and trial design.

## Key findings

- Only 13 multicenter RCTs were identified, involving 2765 participants across nine countries.
- Most trials focused on anesthetic maintenance or opioid regimens, with limited attention to patient-centered outcomes.
- Over half of the trials were judged at high risk of bias, and long-term outcomes were rarely assessed.

## Abstract

Background/Objectives: Anesthesia for intracranial neurosurgery presents unique challenges because of the sensitivity of the brain to perioperative physiological disturbances, yet neuroanesthetic practice remains highly variable and supported by a limited high-level evidence base. We conducted a scoping review to map and characterize multicenter randomized controlled trials (RCTs) evaluating perioperative management strategies in adults undergoing intracranial neurosurgery. Methods: This scoping review was reported in accordance with the PRISMA extension for Scoping Reviews. MEDLINE, PubMed, EMBASE, Cochrane Central, and Web of Science were searched from inception to 25 June 2025. Multicenter RCTs enrolling adults undergoing intracranial neurosurgery and evaluating anesthetic, hemodynamic, ventilatory, or perioperative interventions were included. We prioritized mapping multicenter designs for their greater external validity and implementation potential. Data were extracted in duplicate and summarized descriptively. Results: Of 417 records identified, 13 multicenter trials (≥2 recruiting sites) involving 2765 participants across nine countries from 1997–2025 were included. Most trials evaluated anesthetic maintenance or opioid regimens (7/13), followed by post-craniotomy pain control (3/13), ventilation/brain relaxation strategies (1/13), antiemetic prophylaxis (1/13), and temperature management (1/13). Outcomes were predominantly short-term and process-based (hemodynamics 7/13, opioid use 7/13, emergence metrics 5/13). Patient-centered outcomes were rarely measured (mortality 1/13, functional neurological outcome 1/13, cognitive outcome 1/13; quality of life 0/13). Only one trial assessed outcomes at ≥72 h postoperatively. Over half of the included trials were judged at high risk of bias. Conclusions: Multicenter RCT activity in neuroanesthesia remains sparse and narrowly focused, highlighting the need for larger, methodologically robust trials targeting patient-centered and long-term outcomes.