Presurgical Mapping in Children and Adults
For a neurosurgeon considering treatment options for diseases such as brain tumours and epilepsy, a primary concern is how to provide the most effective treatment, while minimizing possible side effects. Tumours may occur in or near brain areas involved in language. Some tumours “push” on the healthy brain, distorting its shape and making it difficult to know just by looking at the anatomy where the areas that normally support language are. Other tumours “infiltrate” healthy tissue, and on an anatomical MRI it can be difficult to tell just where the borders of the tumour are. By using fMRI, we can “light up” the areas of the brain involved in language, showing surgeons where these critical regions are before the surgery is performed. This can help inform the surgical approach that is taken, and these maps can be viewed in the OR to help guide the surgery.
Working with adults with brain tumors, we have developed a set of three language tasks that provide reliable maps of language centres. We have shown that these maps are reliable for a given individual – if we put the same person in the MRI a second time, we get very similar maps. Working directly with surgeons in the OR, we have also shown that the fMRI maps line up nicely with the neurosurgical “gold standard” – directly stimulating the surface of the brain.
We are also developing a new presurgical protocol for children with epilepsy and other brain diseases. Just as children are not simply “short adults”, fMRI protocols used for mapping language areas in adults are not well-suited for children. They are typically long and boring. Getting good fMRI images requires that people lie still during the scans, which can last 5-10 minutes – again, a challenge for many children! With these facts in mind, we are investigating different paradigms that are more entertaining and game-like. Our goal is to identify the activities that children most enjoy, and that also give us reliable language maps while getting the children in and out of the MRI as quickly as possible.