Untitled Page

Minimally Invasive Brain Surgery

Kathleen Khu
Kathleen Khu

Neurosurgery has not traditionally been considered an area of surgery which could lend itself to minimally invasive techniques. But minimally invasive brain surgery (MIBS) has evolved to include small skin incisions, better illumination, and minimal disturbance of the normal brain tissue. The philosophy is to create as little disruption to the patient as possible - the clinical value of minimally disrupting the patient's tissues is to allow the patient to recover quickly and resume his/her normal life as soon as possible.

Neurosurgical technique has progressed, and advances in anaesthetic techniques and medical technology, such as neuronavigation and improved optical devices, have also played a crucial role in enabling MIBS. There are also exciting advances in minimally invasive spine surgery which will revolutionize this area of surgery. Some exciting examples of MIBS being performed at the Toronto Western Hospital (TWH) are described below


Mark Bernstein
Mark Bernstein

In late 1996, the first awake outpatient craniotomy in the world was performed at TWH. Since then, almost 400 brain tumour patients have been operated on, on an outpatient (i.e. Day Surgery) basis, with low morbidity and high patient satisfaction.

Awake outpatient craniotomy with brain mapping has been found to be a safe and effective procedure for the surgical treatment of patients with gliomas and metastatic tumours. The patient is discharged after 6 hours post-op, assuming a CT done at 4 hours shows no problems and the patient remains well.

An important adjunct that greatly facilitates outpatient surgery is the use of image guidance for the localization of brain tumours. With the neuronavigation system, the location of the tumour is more easily pinpointed, minimizing disturbance to the normal surrounding brain and saving operative time. In addition, the skin incision and the bone flap are smaller and tailored to expose the lesion, lessening the patient's post-op pain and discomfort. Many patients report that going home on the same day makes them feel better overall. They recover faster at home, within a familiar environment, giving them more confidence to resume their day-to-day activities. Outpatient brain surgery is slowly catching on outside Toronto and represents a major advance in patient care and patient flow, minimising the use of shrinking inpatient resources.


Aneurysms have traditionally been approached through large bone flaps. However, the actual working space for the exposure, dissection, and clipping of anterior circulation aneurysms is small, so as long as the principles of minimal brain retraction and proximal vascular control are followed, patient outcomes after aneurysmal clipping using small versus large openings are comparable.

Examples of keyhole approaches to anterior circulation aneurysms include the supraorbital and the micropterional approach. The former involves a skin incision above the eyebrow and the latter involves a small curvilinear skin incision at the temple; in both cases a dollar coin-sized craniotomy is fashioned. In both approaches, the aneurysm is dissected and clipped using the usual microsurgical techniques. Narrower instruments are needed to fit through the opening without obscuring the view.

Focused approaches such as these would have less morbidity since only the relevant structures are exposed. Smaller incisions heal faster, are aesthetically more pleasing, and promote faster recovery. Unruptured aneurysms can be operated on an outpatient basis.


The majority of sellar tumours have been approached through the transsphenoidal route for decades, and tumour resection has traditionally been accomplished with the use of the operating microscope. Over the past few years, the endoscope has been introduced initially as an adjunct to the microscope, until pure endoscopic techniques have been developed to supplant the microscope. Expansion of the bony resection results in the endoscopic endonasal transbasal approach.

The transbasal approach still utilizes the natural corridors leading from the nasal cavity to the sellar region of the skull. These tumours are outside the brain so this approach is ideal in that it allows safe and effective tumour resection with minimal anatomic disruption of the brain.

The advantage of the endoscopic technique over the microscopic one is that the former requires no mucosal incisions, allows a wider and more magnified view of the operative field, and is able to visualize areas that are outside a microscope's line of sight. It also rarely requires nasal packing post-operatively. Overall this technique gives better visualization of the tumour and causes less patient discomfort compared to the traditional microscopic approach. The true advances involve expanding the clinical applications to remove much larger lesions such as skull base meningiomas with minimal touching of the brain.


Gamma Knife stereotactic radiosurgery (GKSRS) is an outpatient procedure in which a highly focused dose of radiation is delivered in a single fraction. It is in reality a radiation procedure but it was initially developed and championed almost entirely by neurosurgeons and many leaders in the field now call it "Gamma surgery". It allows the treatment of discrete lesions with high comformality using three-dimensional stereotactic imaging and the delivery of multiple radiation beams focusing on the target lesion. The beams are so precise that the surrounding normal tissue receives minimal radiation. GKSRS is used to treat a variety of conditions, such as benign tumours (mainly vestibular schwannoma), malignant tumours (mainly metastases), vascular lesions (AVM's), and functional disorders (mainly trigeminal neuralgia).

Gamma Knife
Gamma Knife

On the day of the procedure, a stereotactic frame is applied on the patient's head and screwed into place. The patient then undergoes imaging with the frame in situ. Treatment planning is done, after which the patient receives the actual treatment. Afterwards, the frame comes off and the patient can go home after one hour of observation.

Compared to the surgical alternative, GKSRS is much less invasive and provides similar success rates. It has been proven to be a safe and effective mode of treatment, especially for patients with deep-seated lesions and for elderly patients with medical co-morbidities who would have high surgical risks.

Kathleen Khu,
Clinical Fellow in Neurosurgical Oncology,
Toronto Western Hospital

Mark Bernstein,
Professor of Surgery and Neurosurgeon at Toronto Western Hospital

Skip Navigation Links