Neurosurgery performed for tumors or any brain lesion on patients when they are awake (sometimes sedated) is advantageous. Such type of surgery is known as intraoperative brain mapping, or awake brain surgery. The Neurosurgeons perform such procedure where the removal of tumors would otherwise prove risky. These conditions are –
- When the tumors or the brain lesions are in close proximity to the centres of the brain that control vision, language (motor or speech area) and body movements.
- When the procedure might involve a significant loss of vital function (1)
Awake surgery for tumor patients allows maximizing the extent of resection while preserving brain functions (2).
This technique is typically performed in the resection of brain tumors such as gliomas and metastatic brain tumors. The protocol followed during such type of surgery is to give the patients standard “asleep-awake-asleep” anesthesia. It involves sedation for the first part of the procedure. There after the neurosurgeon creates a small aperture in the patient’s skull (3). Once close to the tumor, the patient is gently awakened. The neurosurgeon then will stimulate the surrounding area of the tumor with small electrodes. It is crucially essential to not to cause any damage to the functional area of the brain. To attain this the neurosurgeon will instruct the patient to talk, counting or identify pictures (1).
With the aid of the computer, images of the brain secured before and during the procedure and the patient’s responses, the neurosurgeon creates a map of the functional areas of the brain. Once the mapping is done it becomes easy for the neurosurgeon to remove the tumor without compromising the functional areas of the brain (1). In cases if the stimulation causes any hindrance in the patient’s communication or the patient appears disoriented the surgeon restricts going further in the resection of the tumor. Functional MRI (fMRI) is a neuro-monitoring device used to evaluate the patient’s response to understand whether it is safe to remove the tumor intotal or partial. Thereafter the patient is sedated again (3).
It is imperative that throughout the procedure the pain does not experience any pain. The neuroanesthesiologist also confirms that the vital signs (heart rate, breathing, and blood pressure) stay stable and also converse with the patient (1)
The risks involved in awake craniotomy for a brain tumor remain the same as those for conventional surgery, however there is statistically some evidence of occurrence of seizures during the procedure that might require the need of general anaesthesia. The complications are rare in awake brain surgery and the overall risk varies with the location, extent and type of the tumor. There is less than 5% incidence of occurrence of permanent neurological deficit or death (4).
Combining brain mapping with awake brain surgery, the neurosurgeons can handle the surgery much more precisely and preserve the functionality of the eloquent or the vital reas close to the lesion like the speech and motor area. Awake brain surgery or the awake craniotomy offers a lesser hospital stay as well. (5)
Resources –
- https://www.hopkinsmedicine.org/neurology_neurosurgery/centers_clinics/ionm/types/intraoperative-brain-mapping.html
- https://www.frontiersin.org/articles/10.3389/fnhum.2013.00405/full
- http://www.pacificneuroscienceinstitute.org/blog/brain-tumor/the-evolution-of-awake-brain-surgery/
- http://www.uhs.nhs.uk/OurServices/Brainspineandneuromuscular/Neurosurgery/Diagnosisandtreatment/Braintumours/Awakecraniotomy.aspx
- https://www.barnesjewish.org/Medical-Services/Neurology-Neurosurgery/Neurosurgery-Procedures/Awake-Craniotomy-and-Brain-Mapping