Dr. Sabana Munsi

Brain mapping is a technique where the biological quantities of a human brain are represented as spatial quantities resulting in maps. As with many other medical technologies, brain mapping is fast-evolving as well. Among several uses, brain mapping is chiefly used while performing surgery on the brain.

When surgery is to be performed on the brain such as surgery for epilepsy, the surgeon would want to comprehend how the brain areas are affected by seizures. The surgical intervention is meant for removing as much as seizure focus as possible while preserving crucial functions like understanding, speech, vision, movement, and sensation.

Why is brain mapping performed?
Brain mapping is a process which helps in identification of functions of various parts of the brain. Mapping the brain by stimulating different areas of the brain areas can aid in creating a map for a particular person. The map allows the doctor in understanding what parts of the brain are responsible for performing critical functions including sensation, movement, speech and other functions.

Which functions of the brain can be mapped electrically?
Typical areas of the brain which have motor, language, visual and sensory functions are needed to be mapped. When current is applied to a single area at a time, the doctor understands which part of the brain is responsible for which function.
When the patient is not able to speak due to the current, then the area is likely to be crucial for language function. If the limbs, face or trunk of the patient stop moving as the current passes, the area that is tested is responsible for movement. On the other hand, if the individual experiences tingling, numbing, and other sensations when the current is applied, it means that a sensory region is discovered.

How is electrical brain mapping performed?
Electrical brain mapping for guiding brain surgery for epilepsy can be performed in two distinct processes: directly during the surgery or in a two-stage procedure.

Two-stage procedure:
In the first stage of the process, the surgeon creates an opening in the skull which helps in exposing the surface of the brain. Small electrical contacts or electrodes are placed on the brain surface even though no brain tissue is removed. As soon as the electrodes are in the right position, the scalp is closed. The electrodes not only record the seizure of the patient electrically but also allow mapping of various areas of the brain. The last stage is surgery where abnormal brain tissues are removed.

Brain mapping process during surgery:
Electrical brain mapping may also be performed during the surgery which exposes part of the brain. This is termed as intraoperative brain mapping since it occurs while performing the main operation. The process of mapping may last for an hour to several hours at a stretch.

Brain mapping is also used to diagnose neurodegenerative diseases like Alzheimer’s and Parkinson’s. In these cases, the brain map shows extreme shrinkage of the brain due to tissue loss. In case you have a concern or query you can always consult an expert & get answers to your questions!