In certain cases a tumor may be infiltrating brain tissue that is involved with some essential function such as language. In these cases awake craniotomy can be used to safely perform surgery on these lesions. This is done with the cooperation with the anesthesiologist who is responsible for putting a patient to sleep and maintaining vital functions during an operation. It is important that this type of procedure be done with a neuro-anesthesiologist who has experience with awake craniotomy techniques. During such a procedure the patient is fully anesthetized and asleep during the opening and closing portions of the surgery. After the brain is exposed, the patient is brought into a conscious state. Relevant areas of the brain can then be stimulated to assess for function and to decide what tissue can or cannot be safely removed. The patient feels no pain during this procedure as local anesthetic has been given to completely numb the region. Although this technique adds to the complexity and length of an operation, it can dramatically improve the safety of such a procedure.