Neurologists and researchers at the University Hospital Brussels and the Free University of Brussels have tested the use of an augmented reality (AR) headset and technology that allows the placement of intracranial drains to be performed more accurately. Their pilot study shows that the AR method provides fewer complications and also requires fewer additional procedures than fully manual placement of these drains.
The AR system consists of Microsoft's HoloLens II augmented reality headset combined with surgical navigation software custom developed by the researchers. The solution integrates all the components needed for neuronavigation (i.e. high-precision tracking, image display and processing unit) into a standalone headset, without external cameras or computers.
3D model
In preparation for placement of an intracranial drain with the AR system, a 3D model of the patient's anatomy is created. This is then labeled with coordinates relevant to AR guidance, including Monro's foramen as a target point. An infrared-labeled reference frame is attached to the patient's head with a clamping headband, allowing the AR application to track the position and orientation of the head.
The 3D model is exported to the AR headset in the surgical navigation application and image-patient registration is performed with an infrared tracked stylus to match the virtual representation of the patient's anatomy with the physical representation. During EVD trajectory planning, the system determines the path to Monro's foramen with the shortest distance between the skin surface and the ipsilateral frontal horn of the lateral ventricles to ensure the shortest path through the brain parenchyma.
Drain placement
During drain placement with the AR method, by moving a stylus around the expected entry point, the surgeon can make adjustments in real time, taking into account underlying anatomy or pathology of the patient
The trajectory and all necessary anatomical information are displayed as a 3D object on the patient and can be inspected from all angles, giving a sense of depth. A tracker is attached to the surgical drill and the system indicates the translation and angular error of the drill tip and drill direction based on the planned trajectory.
Successful pilot study
After successful phantom studies, Dr. Van Gestel and three other neurosurgeons tested the AR navigation system in 11 patients requiring intracranial drain placement. The findings of placement using the AR system were compared with data from 11 other patients in whom such a drain was placed entirely manually.
The pilot study found that the use of the AR system led to better placement results and also better functional placement. The drain was successfully placed nine times using the AR system, versus five times using the manual method. In eight cases placement with AR was optimal, versus three with manual placement. No AR placement failed, versus one failed manual placement. No AR-guided placement required revision; four manual placements did.
“Although free-hand placement might have been equally successful in some cases, the marked improvement over the control group indicates that the free-hand technique may not produce consistently good results. Performance in cases with ventricular aperture further supports these assumptions, as achieving successful ventricular puncture can be particularly challenging, especially within a single attempt,” said Dr. Van Gestel and colleagues.
