What is intraoperative brain mapping ("awake brain surgery")?
Neurosurgeons at the Johns Hopkins Comprehensive Brain Tumor Center perform many brain tumor procedures while the patient is awake but sedated. This procedure is called intraoperative brain mapping, or awake brain surgery. It enables the neurosurgeons to remove tumors that would otherwise be inoperable because:
- They are too close to areas of the brain that control vision, language and body movements
- Surgery would result in a significant loss of function.
Neurosurgeons perform awake brain surgery for tumors that have spread throughout the brain and do not have clear borders, such as some types of glioma. Awake brain surgery can shrink these tumors.
How awake brain surgery works:
The procedure is performed after the patient’s scalp is numbed and usually with the patient sedated.
The neurosurgeon works very closely with the neuroanesthesiologist. Together, they will decide if awake brain surgery is right for a particular patient, depending on:
- The importance of awake brain surgery in removing the tumor without damaging critical parts of the brain
- The patient’s general health (e.g., awake brain surgery is not performed in patients with some types of sleep apnea and those who are obese)
- Whether the patient will be able to remain calm during the procedure and respond to the neurosurgeon
If they recommend awake brain surgery and the patient agrees, the neuroanesthesiologist will explain the procedure in detail and answer the patient’s questions.
The neurosurgeon and neuroanesthesiologist will work together to determine the most appropriate type of anesthesia for each patient. The patient may be:
- Awake throughout the procedure: The patient will receive a nerve or scalp block — an injection of medication to block pain — and local anesthesia — medicine to numb a small part of the body — on the scalp.
- Sedated at the beginning and end of the procedure and awake in the middle: The patient will receive a scalp block and a little anesthesia for sedation at the beginning of the procedure. The neuroanesthesiologist stops the sedation when the neurosurgeon is ready to remove the brain tumor. After that, the neuroanesthesiologist sedates the patient again.
- Put to sleep at the beginning and end of the procedure and awake in the middle: The patient will receive a nerve block and general anesthesia — medicine that makes the patient unconscious. The neuroanesthesiologist will wake the patient up when the neurosurgeon is ready to remove the brain tumor and put the patient to sleep again after that.
During surgery, the neurosurgeon will stimulate the area around the tumor with small electrodes. To precisely locate the functional areas of the brain that must be avoided, the neurosurgeon will ask the patient to perform tasks such as talking, counting and looking at pictures.
The neurosurgeon will use computer images of the brain taken before and during the procedure and the patient’s responses to create a map of the functional areas of the brain. The neurosurgeon then removes as much of the tumor as possible while avoiding the functional areas of the brain.
Throughout the procedure, the neuroanesthesiologist will ensure that the patient does not feel any pain, monitor vital signs (heart rate, breathing, and blood pressure) and talk to the patient to help the patient remain calm.