Neuronavigation / Frameless Stereotaxy / Image-Guided Neurosurgery

In essence these terms are interchangeable and all refer to computer-based technology employed during an operation to guide the surgeon more accurately than is possible with freehand techniques. These are commercially available systems that use either infra-red light detectors or magnetic field distortion measurements to track the surgical instruments. These instruments or their tip positions are then displayed on the computer screen relative to the equivalent position in the patients scan. The surgeon can "interrogate" the system by requesting images of the instruments projected path, updated in real-time whilst moving the point across the skin surface (i.e. what structures are in the path if I entered here?). Pre-operative plans can be stored and subsequently followed intra-operatively, 3D models created and cut-away views shown that all assist the surgeon.

These systems use the patient's own scans (usually MRI or CT) and therefore enable the surgery to be tailored to the individual and their pathology. Therefore, there is no longer a 'standard' approach to any neurosurgical target. The systems can be used for guidance during open surgical procedures (craniotomy and spinal surgery) as well as Stereotactic biopsy (needle biopsy of brain lesions) and minimally-invasive endoscopic, pituitary or spinal procedures.

Mr Dorward was involved in the development of these systems in his research and has written landmark academic papers on the accuracy of navigation systems, the extent and impact of brain-shift during open surgery and the time benefits of employing neuronavigation in cranial surgery. He was awarded a Master of Surgery degree for his thesis "Development and Evaluation of Image-Guided Neuroendosopy, with Investigation of Post-Imaging Brain Distortion and Accuracy of Frameless Stereotaxy"

Whilst a patient may not realise that Neuronavigation could be used in their operation, they will see the benefit through having had a smaller more accurately defined operation and improved outcome. As the images are specially acquired most patients will need an additional MRI or CT scan just prior to surgery.