Do you need to be woken up during craniotomy? What is the purpose of this?

Author: Han Ruquan, Chief Physician, Beijing Tiantan Hospital, Capital Medical University

Reviewer: Xing Yan, Chief Physician of Aviation General Hospital

During brain tumor removal surgery, the skull must be opened, the tumor location must be accurately found under a microscope, and then it must be removed as completely as possible.

Generally, craniotomy is performed under general anesthesia, but did you know that in some cases, it is sometimes necessary to wake the patient up during craniotomy and perform brain function tests, which is called awakening anesthesia?

1. What is awakening anesthesia for craniotomy?

The functions of the brain are very complex. Different brain areas are responsible for their own specific functions. For example, this area is responsible for limb movement, another area is responsible for language, and there are also areas responsible for vision and hearing.

Figure 1 Original copyright image, no permission to reprint

If the tumor involves the brain functional area, especially the language functional area, during the tumor resection process, if the language functional area is damaged, aphasia may occur after surgery. The cerebral cortex function has a very good remodeling mechanism. If language dysfunction occurs after surgery, some patients may recover through long-term functional remodeling.

In order to avoid damage to brain function, especially language function, during tumor resection, the best method is to wake up the patient during surgery and perform positioning and functional testing of specific functional cerebral cortex. The purpose is to maximize tumor resection while minimizing damage to functional brain tissue, so that the patient can return to normal life after surgery, speak normally like before the operation, and communicate with relatives and friends. This is the significance of awakening anesthesia during surgery.

The vast majority of patients undergo brain tumor surgery under general anesthesia, and only when the tumor is located in an important functional area does it require intraoperative awakening. Intraoperative awakening is only required when the tumor is in the language function area, visual center, and a small part of hearing loss and the cochlear nerve nucleus is implanted. In the early days, awakening was also performed when the tumor was in the motor function area. With the continuous advancement of technical means, other methods such as electrophysiological monitoring can accurately locate the functional area and no awakening is needed.

If the location of the tumor is related to language function, it is necessary to focus on testing the patient's language function. Let the patient look at pictures and say what the pictures are and how to pronounce them. Sometimes English or Chinese-English translation is also required. If the area where the tumor is located is related to vision, visual field tests should be conducted.

With current technology and methods, patients will not feel pain during the awakening stage of the operation through scalp nerve block anesthesia, combined with systemic analgesics, local anesthesia, etc. In addition, the use of anesthetics can make patients feel euphoric, and they will not feel pain or nervous during the operation, and can happily cooperate with the doctor to do a good job in the functional area test.

2. Are there any risks in performing awakening anesthesia during craniotomy?

Intraoperative awakening anesthesia itself still has many risks, and strict screening indications before surgery are very important.

For example, patients who smoke heavily for a long time are not suitable for awakening anesthesia, because there may be a lot of secretions and coughing during the operation, which will affect the progress of the operation and bring risks to the patient. Some tumors progress very quickly, and there are problems with consciousness before the operation, which means that when the functional test is done during the operation, the patient cannot cooperate well with the anesthesiologist. In addition, although there are ways to make the patient feel euphoric, there are a few patients who are nervous and anxious. They cannot tolerate any external stimulation during the operation. They may be uncooperative and agitated during the operation. This situation also brings many risks to the patient, and these are not suitable for awakening.

3. How is anesthesia performed during craniotomy during awakening anesthesia?

The anesthesia implementation process can be roughly divided into three stages.

The first stage is the craniotomy period, which exposes the cerebral cortex; the second stage is called the awakening period, which localizes the function of the cerebral cortex and removes the tumor. During the tumor removal process, some patients also need to make sure that their functions are not damaged; the third stage is called the cranial closure period.

Before the first stage, effective analgesia and scalp nerve block anesthesia are required, and general anesthetics are also given to put the patient under general anesthesia. After opening the bone flap, the patient needs to be awakened and the infusion of general anesthetics is stopped. The patient gradually enters a wakeful state and can communicate verbally or complete tasks. After completing this stage, drugs are infused and then the patient enters a general anesthesia state. The drugs and anesthesia methods used in different stages are different.

Before each awakening operation, the anesthesiologist will chat with the patient in the afternoon of the day before the operation. The purpose is to obtain the patient's basic information, including interests and hobbies, and psychological state.

Figure 2 Original copyright image, no permission to reprint

On the other hand, we need to establish a very good trusting relationship with the patient, because surgery is now more of a process from general anesthesia to awakening. During the awakening period, the patient can feel that there is a trusted anesthesiologist by his side, and will cooperate with the anesthesiologist in a half-asleep state, listen to the anesthesiologist's instructions, and complete some necessary work and necessary cooperation.

During the awakening process, I recommend that the doctor hold the patient's hand. This subtle action can give the patient great psychological comfort and support, and his unstable emotions may be stabilized by holding hands.