Awake Craniotomy / Speech Mapping

A craniotomy is a procedure in which the skull is opened to access the brain. Most of the time, craniotomies are performed with the patient under general anesthesia (asleep). In some cases, however, there is value in mapping the surface of the brain to determine the safest way to perform a surgery. Certain forms of brain mapping, particularly the mapping of speech, require the patient to be awake and interactive. In these cases, I use a technique called an awake craniotomy.

Why map a brain function like speech? The parts of our brain used for speaking are similar in location but vary slightly from one person to the next. If a tumor or other lesion is located near a speech region, keeping the patient awake and testing their speech during the operation allows me to reduce the risk that speech will be affected by the procedure. In other words, mapping allows me to avoid damaging important brain functions that I am trying to preserve.

In an awake craniotomy with speech mapping, the patient is kept sedated (but not under general anesthesia) until it is time to map the brain. The sedation is then lightened so that the patient can participate in testing. This procedure is not painful, since the scalp is anesthetized with numbing medicine, and the skull and brain do not have any pain fibers. A probe is used to apply painless electric current to the surface of the brain while a patient is speaking, and I identify the areas where his or her speech gets interrupted by the electric current. This allows me to determine which areas are essential for speech and which are not. Based on what I find, I can plan the safest way to perform the operation.

Below are two photos of an awake craniotomy I performed for removing a tumor in the left temporal lobe. The first shows the surface of the brain during speech mapping, and the second shows the sites that were important to the patient’s speech (yellow stars). I used this mapping to remove the tumor without violating the speech center.

I use mapping commonly when removing brain tumors - both speech mapping as well as another technique called motor mapping, which allows me to identify and avoid the motor (movement) center and fibers in the brain. Motor mapping is different than speech mapping in that it can be performed with the patient asleep.