Awake Brain Mapping FAQ

Awake Brain Mapping FAQ


Why is awake brain mapping done? 

Awake brain surgery (also called awake craniotomy) is done in cases when a tumor is close to regions of the brain that control language, cognition, sensation, and body movement. This allows the surgical team to precisely map out important areas of the brain to avoid during the surgery, in order to protect the patient’s language, sensory, and motor abilities. 

Before the surgeons remove any brain tissue, the area surrounding the tumor is tested for its role in critical brain functions. The technique is called awake brain mapping, which involves asking the patients to do various tasks while specific parts of the brain are stimulated. Patients assist the process by answering questions (like counting or reading), to identify which parts of the brain are critical for functions like language or body movement. This allows the surgeons to remove as much of your tumor as possible, while preserving critical brain functions. 

Awake brain surgery is possible because there are no pain receptors in the brain itself. Your scalp will be anesthetized, so you will not feel the operation or any pain. 

Read more about awake brain mapping (also called intraoperative mapping). This type of procedure is also done in cases of epilepsy, if the site where the seizures originate is near language, sensory, and motor regions of the brain. 

How common is this procedure?

Since 1998, the UCSF Neurosurgery team has performed over 1,200 awake brain surgeries for epilepsy and brain tumor patients. Many of the techniques for awake brain mapping were developed and pioneered by Dr. Mitchel Berger, the director of our Brain Tumor Center. Our multidisciplinary brain mapping team includes neurosurgeons, neuro-anesthesiologists, speech and language specialists, neurologists, and psychologists. 

Which tumor types will require awake brain surgery to remove?

Awake brain surgery is considered for any patient with a tumor located within or near regions of the brain controlling critical functions like language, sensation, and body movement. Awake brain mapping is considered the gold-standard for identifying and preserving those important areas of the brain during surgery. It is well established that greater extent of tumor resection (or removal) leads to better patient outcomes, and awake brain mapping is a critical component in maximizing tumor removal while preserving a patient’s neurological functions. 

Tumor types that may be considered for awake brain surgery include any tumor embedded within the brain (intrinsic brain tumors) such as grade I-IV gliomas, oligodendrogliomas, ependymomas, and brain metastasis. Ultimately, the recommendation for awake brain surgery depends on a number of factors, including tumor size and location, as well as the patient’s overall health and medical history. 

What can I expect during the surgery?

While your neurosurgeon and neuroanesthesiologist will work together to determine what kind of anesthesia is best for you, typically patients are sedated during the beginning and end of the procedure, with local anesthesia throughout. 

Once the brain is exposed, the neuroanesthesiologist will wake you up for the brain mapping procedure. Your neurosurgeon will begin stimulating different parts of your brain, by applying small electrical currents to the tissue around your tumor. You will not feel pain during this stimulation. Depending on the location of your tumor, you may experience different sensations. Electrical stimulation of the motor regions of the brain will cause specific muscles to contract, like in your leg or arm. Stimulation of sensory regions of the brain will result in a tingly feeling on specific part of your body, like your face or feet. Stimulation of the language regions of the brain will temporarily cause you to make errors or stop speaking. A neurophysiologist will be monitoring your reactions throughout the procedure, to help identify and protect important regions of the brain during surgery. To do so, your neurophysiologist may ask you questions about how you are feeling, in addition to having you complete certain tasks like counting, reading, or naming objects in pictures. This brain mapping procedure continues as your tumor is removed, so your neurosurgeon knows exactly which regions of the brain to avoid. 

Throughout the surgery, the neuroanesthesiologist will be monitoring you, talking with you to keep you comfortable, and making sure you are not in pain. Once the tumor is removed, the neuroanesthesiologist will allow you to go back to sleep for the remainder of the procedure. 

How long is a typical surgery?

The length of an awake brain surgery varies, depending on the location and extent of the tumor. Your operating team will be continually mapping your language, sensory, and motor responses as the tumor is carefully removed to make sure important brain regions are protected; this brain mapping procedure varies in duration, and depends how close your tumor is to these critical regions. Typically, awake brain surgeries can last 4-8 hours. The most important part of the day is your safety. As long as you are safe and comfortable the mapping procedure will continue until the tumor is removed.

What can I expect after the surgery?

After the surgery, your doctors may take another MRI to make sure the tumor was fully removed. Tumor tissue collected during the surgery will be analyzed and may guide future treatment. 

The length of post-operative recovery depends on a variety of factors, including the location of the tumor. You can probably expect to stay in the hospital for 2-4 days. Some patients may stay longer if additional treatment is required.

Before you are discharged, rehabilitation therapists will check on your recovery and make sure you can safely resume daily activities like walking, dressing, and using the bathroom. Depending on the location of the tumor, a speech therapist may also help evaluate your speech and language.

What will recovery be like?

Like with any major operation, full recovery may take a few weeks. During the first few weeks, you may feel tired and take frequent naps, but you should be able to remain active and participate in light duties around the house. Generally, you will be able to return to work and other normal activities in 6 weeks to 3 months.

Your first follow-up appointment will likely be 10-14 days after the surgery to check your incision. Your doctor will check on your recovery, answer any questions you may have, and if applicable, give you tissue analysis results from the operation. Together, you will decide on options for future care, including additional follow-up appointments. Many patients will follow their surgery with radiation therapy and chemotherapy.

What are the risks of awake brain surgery?

Awake brain surgery carries many of the same risks as conventional brain surgery. These depend on a variety of factors, including the location, size, and type of tumor, as well as your age and general health. While your doctors will advise you on your particular risks, long-term complications resulting in neurological deficit (like numbness, weakness, or impairments in speech) are uncommon and occur with an incidence of less than 2-3%. The purpose of awake brain mapping is to protect important brain regions and minimize the chances of neurological deficits. 

Your doctor will discuss the full risks in detail with you, but some of the possible complications of awake brain surgery include the following:

  • Temporary or permanent neurological deficit
  • Seizures
  • Hematoma
  • Infection
  • Stroke

This content was reviewed by UCSF neurosurgeons, Mitchel Berger, MD and Shawn Hervey-Jumper, MD.