External ventricular drainage in modern neurosurgical practice: optimization, standardization, and emerging guidance technologies.

External ventricular drain (EVD) placement is a standard neurosurgical procedure for cerebrospinal fluid diversion and intracranial pressure monitoring, yet conventional freehand techniques are associated with substantial variability in placement accuracy and complication risk. Anatomical distortion and ventricular compression commonly seen in the setting of pathology further limit the landmark-based reliability of freehand drain insertion, increasing the likelihood of multi-pass attempts and suboptimal catheter placement. Consequently, adjunct guidance technologies, including ultrasound, electromagnetic neuronavigation, and augmented reality (AR) platforms have been developed to improve procedural precision and consistency. This review examines current evidence comparing freehand and technology-assisted EVD placement, integrating an overview of the technical principles underlying contemporary guidance systems with a synthesis of comparative clinical outcomes across modalities. Reported clinical evidence suggests guided techniques can improve catheter placement accuracy and first-pass success, while workflow impact varies by modality and institutional experience. Electromagnetic navigation demonstrated consistent performance across settings, with AR platforms representing an emerging approach with potential advantages in portability and ease of integration. Continued efforts toward procedural standardization and prospective validation may further define the role of guided techniques in advancing patient safety and reducing variability in ventriculostomy practice.