Anesthesia and Awake Craniotomy - Essay Example

Such recording is termed electrocorticography (ECoG). The use of ECoG allows a "topographical map" to be made of the brain. This map shows the locations of primary and secondary epileptogenic discharges, as well as the route and extent of the spread of such electrical activity. [3, 4, 5 and 6] At our institution, patients undergoing craniotomy while awake usually have a tumor or epileptic foci removed. Patients who undergo the removal of a tumor close to a motor, speech, or sensory area generally are awake before resection is begun so that neurological function can be tested.

[7, 8, 9, 10, 11 and 12] In these patients, ECoG is not usually performed. However, other physiological monitoring, such as sensory evoked responses (SER) and/or electromyography (EMG), may be used. [13] Patients who undergo removal of an epileptic focus in the brain are also generally awake for neurological function testing. In addition, ECoG is almost always performed. Awake testing includes some or all of the following: immediate and/or delayed memory, association, and/or pattern discrimination of words and/or pictures, and other related tests.

[14, 15, 16, 17, 18 and 19] Awake testing may also include motor movement in response to electrical stimulation, voluntary motor movement, muscle strength, and other related tests. [20] These tests are often complex and subtle, and require that the patient's consciousness not be impaired by anesthetic or other drugs. The other types of monitoring that may be performed include ECoG, SER, and/or EMG. These modalities are all impaired in a dose-related manner by many anesthetic drugs. Clearly, if the aforementioned testing is to be used, the interference of anesthetic drugs is not wanted.

[21 and 22] Our approach to anesthetic management for awake craniotomies has evolved over more than 30 years in cooperation with surgeons at our institution internationally known for their work in this area. The approach we use today is an improvement over the one we used decades ago and, no doubt, the approach we will use several decades from now will be different than the one we use today. The follow sections describe our current guidelines. Guidelines for awake craniotomyGoalsAt each stage of the procedure, our management goals are tailored to the specific needs at that stage.

One of the rather alarming aspects of our approach is that even though the patient is anesthetized for parts of the procedure that don't require the patient to be awake, we do not secure the airway with a laryngeal mask airway (LMA), endotracheal tube, or similar device. Thus, one of our goals is careful monitoring of the airway to prevent undetected airway obstruction. A large proportion of the patients undergoing awake craniotomy at our institution have epilepsy that is not controllable with drug therapy.

In such patients, seizures may occur during surgery. Thus, a second goal of anesthetic management is prompt treatment of grand mal seizures. The knowledge of being awake and under surgical drapes while their brain is being operated on concerns many patients. Thus, a third goal of anesthet