Intraoperative

Brain shift

Brain shift is the movement and deformation of the brain during surgery, from CSF loss, gravity, swelling and tumor removal. It makes preoperative neuronavigation progressively less accurate.

Neuronavigation systems register the patient's head to scans taken before surgery. Once the dura is opened, the brain moves: cerebrospinal fluid drains, gravity pulls tissue, swelling develops and removing a tumor leaves a cavity. This deformation is called brain shift.

Shift can range from a few millimeters to more than a centimeter and grows as resection proceeds, so the navigation display drifts away from the true anatomy just when precision matters most, at the tumor margin.

Ways to correct for it include intraoperative MRI, intraoperative ultrasound and computational models that predict how the brain deforms, so that preoperative images can be updated during surgery.

Tools that use this

iUS BrainShift Prediction StudioDeep learning that predicts and visualizes intraoperative brain shift from paired pre- and post-resection ultrasound sweeps. Babel et al., Operative Neurosurgery 2026.

Related terms

Intraoperative ultrasound (iUS)

Educational reference. Not medical advice and not for clinical decision-making.