Navigation for Stereotactic Brain and Spine Surgery
The safest and most efficient access to the area of interest
IMAGE-BASED NAVIGATION FOR BRAIN AND SPINE SURGERY
Less Invasive Procedures
Image-guided or stereotactic surgery describes a procedure where image-based navigation is used to achieve the safest and most efficient access to the point of interest. Its principle is very similar to a car or mobile Global Positioning System (GPS) navigation. Advances in medical technology allowed performing less invasive procedures and treat brain and spine lesions that were previously considered inoperable due to their size or critical location.
A set of specifically designed tracked surgical instruments is used together with cameras or electromagnetic fields and computer software to capture and relay the patient’s precise 3D anatomy in real-time. Spacious visualisation and image manipulation in the operating theatre are based on the same principles as in virtual or augmented reality.
Usually, the high-resolution patient’s images are obtained before surgery with the fiducials placed on the skin and uploaded into the workstation for trajectory planning. This plan creates a virtual patient-specific 3D model of the brain or spine outlining the area of interest and critical surrounding structures.
This individual model has to be registered to the actual patient position on the operating table using infrared cameras or electromagnetic fields. Special optical reflective markers on the surgical instruments can be tracked by the computer and position of the tool can be displayed on the screen or in the operating microscope.
Radiological Imaging Used for Navigation
Magnetic Resonance Imaging (MRI)
Nowadays, MRI is the number one modality in neurosurgical and spinal imaging due to its superb image resolution and contrast. We use it in all patients with brain and spine problems with only rare exceptions when it is not possible due to old cardiac pacemakers, cochlear implants, stimulators or other medical conditions.
High-quality MRI is available not only at a preoperative planning stage but can also be used intraoperatively, e.g. to estimate the extent of tumour resection. These guided procedures normally involve a planning stage, needle/probe insertion, guidance, and then a sample of the lesion is taken
CT is the preferred modality for visualisation of bone and is much more compact than MRI. It is also significantly faster and cheaper, which makes it ideally suited for spine image-guided surgery when accurate placement of vertebral screws is required.
It can also be used for intracranial surgery, including lesion removal, biopsy and other stereotactic procedures. However, it involves radiation exposure and should be used with care. It can also be used in conjunction with other imaging modalities, e.g. SPECT or PET for better representation of metabolic changes and chronic inflammatory conditions.
Fluoroscopy and X-ray C-arms
Although standard x-rays in fluoroscopy provide only two-dimensional images; the technological evolution allowed implementation of rotational C- arms which provide high image quality, compatible with CT scanner.
The images obtained before or during surgery are uploaded into the computer workstation and processed to plan the approach trajectory, position of the lesion, predict placement of the implants, and manipulate 3D views during surgery. The real-time information helps the surgeon to define the most appropriate strategy and to make necessary adjustments straight away if required.
SAFER SURGERY AND FASTER RECOVERY
Advantages over Traditional Open Surgery
The use of navigated technology has multiple benefits for patients when compared to traditional open surgery:
– better quality of treatment, including improved accuracy and complete removal of lesions,
– improved outcomes,
– smaller craniotomy size for removal of the brain tumours and other pathologies,
– decreased incision size with better cosmetic results,
– reduced risk of infection and wound healing problems,
– reduced risk of medical complications, e.g. chest infections and deep venous thrombosis,
– reduced radiation exposure to the patient and operating theatre staff,
– increased safety and avoidance of critical structures during the approach,
– shorter operation time,
– diminished reliance on pain medications after surgery,
– faster postoperative recovery,
– earlier and more efficient physiotherapy and rehabilitation,
– faster return to normal activities and work,
– shorter hospital stay,
– the reduced overall cost of treatment.
IMPROVING OUTCOMES OF BRAIN AND SPINE SURGERY
Image-Guided Technology Applications
Despite advances in modern imaging technology, the only way to establish the histopathological diagnosis is by removing a specimen and investigating it under the microscope. The image-guided or stereotactic technique allows reaching even deep-seated lesions with minimal risk and obtaining samples for histopathological, microbiological and molecular biological investigations. With accurate tissue diagnosis, appropriate treatment of the pathological condition can be provided.
Removal of tumours and other pathological lesions
Successful treatment of brain or spine tumours and other pathological condition often requires the maximum extent of resection with minimal impact on healthy surrounding tissue. Sometimes, tumours don’t have a well-defined border and application of the image-guided technology allows real-time assessment of the surgical cavity and removal of even deep-seated and difficult to access lesions.
Cerebrovascular pathology (cavernomas, arteriovenous malformations, aneurysms)
Vascular lesions can often be very small, positioned deeply in the brain. Accurate preoperative trajectory planning and utilisation of the neuronavigation allows a safe approach to the lesion without disrupting important surrounding neural pathways.
Surgery of seizure disorders involves the removal of the epileptogenic focus or disruption of the epileptogenic activity in the proximity of the critical functional areas. It is often impossible to distinguish epileptogenic cortex from the normal brain tissue even under the surgical microscope.
Thorough preoperative assessment is required for accurate localisation of the focus, and the image-guided technology allows positioning electrodes for monitoring of the brain activity, for example, in the hippocampus precisely. It also facilitates safe removal of the lesion during surgery, allowing preservation of the eloquent structures. Electrophysiological monitoring and intraoperative electrocardiography can be used to confirm the extent of resection.