Awake craniotomy is a neurosurgical technique and type of

craniotomy A craniotomy is a surgical operation in which a bone flap is temporarily removed from the skull to access the brain. Craniotomies are often critical operations, performed on patients who are suffering from brain lesions, such as tumors, blood clot ...

that allows a surgeon to remove a

brain tumor A brain tumor occurs when abnormal cells form within the brain. There are two main types of tumors: malignant tumors and benign (non-cancerous) tumors. These can be further classified as primary tumors, which start within the brain, and seconda ...

while the patient is awake to avoid brain damage. During the surgery, the neurosurgeon performs cortical mapping to identify vital areas, called the " eloquent brain", that should not be disturbed while removing the tumor.

Uses

A particular use for awake craniotomy is mapping the

cortex Cortex or cortical may refer to: Biology * Cortex (anatomy), the outermost layer of an organ ** Cerebral cortex, the outer layer of the vertebrate cerebrum, part of which is the ''forebrain'' *** Motor cortex, the regions of the cerebral cortex i ...

to avoid causing language or movement deficits with the surgery. It is more effective than surgeries performed under general anesthesia in avoiding complications. Awake craniotomy can be used in a variety of brain tumors, including

glioblastomas Glioblastoma, previously known as glioblastoma multiforme (GBM), is one of the most aggressive types of cancer that begin within the brain. Initially, signs and symptoms of glioblastoma are nonspecific. They may include headaches, personality cha ...

glioma A glioma is a type of tumor that starts in the glial cells of the brain or the spine. Gliomas comprise about 30 percent of all brain tumors and central nervous system tumours, and 80 percent of all malignant brain tumours. Signs and symptoms ...

s, and

brain metastases A brain metastasis is a cancer that has metastasized (spread) to the brain from another location in the body and is therefore considered a secondary brain tumor. The metastasis typically shares a cancer cell type with the original site of the ...

. It can also be used for

epilepsy surgery Epilepsy surgery involves a neurosurgical procedure where an area of the brain involved in seizures is either resected, ablated, disconnected or stimulated. The goal is to eliminate seizures or significantly reduce seizure burden. Approximatel ...

to remove a larger amount of the section of tissue causing the seizures without damaging function, for

deep brain stimulation Deep brain stimulation (DBS) is a neurosurgical procedure involving the placement of a medical device called a neurostimulator, which sends electrical impulses, through implanted electrodes, to specific targets in the brain (the brain nucleus ...

placement, or for

pallidotomy Pallidotomy is a neurosurgical procedure. It is used to treat Parkinson's disease and some other conditions, often as an alternative to deep brain stimulation. It involves placing a tiny electrical probe in the globus pallidus, one of the basal g ...

. Awake craniotomy has increased the scope of tumors that are considered resectable (treatable by surgery) and in general, reduces recovery time. Awake craniotomy is also associated with reduced iatrogenic brain damage after surgery.

Technique

Before an awake craniotomy begins for tumor or epilepsy surgery, the patient is given

anxiolytic An anxiolytic (; also antipanic or antianxiety agent) is a medication or other intervention that reduces anxiety. This effect is in contrast to anxiogenic agents which increase anxiety. Anxiolytic medications are used for the treatment of anxiet ...

medications. The patient is then positioned in a neurosurgical head restraint that holds the head completely still and given

general anesthesia General anaesthesia (UK) or general anesthesia (US) is a medically induced loss of consciousness that renders the patient unarousable even with painful stimuli. This effect is achieved by administering either intravenous or inhalational general ...

. The anesthesiologist will then use

local anesthetic A local anesthetic (LA) is a medication that causes absence of pain sensation. In the context of surgery, a local anesthetic creates an absence of pain in a specific location of the body without a loss of consciousness, as opposed to a general a ...

s like lidocaine or

bupivacaine Bupivacaine, marketed under the brand name Marcaine among others, is a medication used to decrease feeling in a specific area. In nerve blocks, it is injected around a nerve that supplies the area, or into the spinal canal's epidural space. I ...

to numb the skin and bone of the head and neck. The craniotomy begins with a surgeon removing an area of the skull over the tumor and cutting into the meninges, the membranes that protect the brain. Before removing any brain tissue, the patient is awakened and the neurosurgeon creates a cortical map, using a small electrical stimulation device to observe the changes in the patient's condition when an area is stimulated. If an area is stimulated and the patient moves or loses some ability, like speech, the surgeon knows that the area is vital and cannot be removed or cut through to access a tumor. During the procedure, the surgeon, anesthesiologist, and other surgical personnel speak to the patient, and there is a technician constantly assessing the patient's ability to name objects, for example, or report any abnormal sensations. There are two variations on the technique: asleep-awake-asleep (AAA), and monitored anesthetic care (MAC), also called

conscious sedation Procedural sedation and analgesia (PSA) is a technique in which a sedating/dissociative medication is given, usually along with an analgesic medication, in order to perform non-surgical procedures on a patient. The overall goal is to induce a decr ...

. In an AAA surgery, the patient is only awake during the cortical mapping; whereas in an MAC surgery the patient is awake the entire time. The procedure for deep brain stimulation placement is similar, though instead of skull being removed, a burr hole is drilled for the electrodes instead and the MAC surgery is more common.

Complications

The complications of awake craniotomy are similar to complications from brain surgery done under general anesthesia –

seizures An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with l ...

during the operation, nausea, vomiting, loss of motor or speech function, hemodynamic instability ( hypertension,

hypotension Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the systolic blood pressure (the top number) and the dia ...

, or

tachycardia Tachycardia, also called tachyarrhythmia, is a heart rate that exceeds the normal resting rate. In general, a resting heart rate over 100 beats per minute is accepted as tachycardia in adults. Heart rates above the resting rate may be normal ( ...

cerebral edema Cerebral edema is excess accumulation of fluid ( edema) in the intracellular or extracellular spaces of the brain. This typically causes impaired nerve function, increased pressure within the skull, and can eventually lead to direct compres ...

hemorrhage Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, v ...

, stroke or air embolism, and death. Seizures are the most common complication.

Contraindications

There are patients for whom an awake craniotomy is not appropriate. Those with anxiety disorders,

claustrophobia Claustrophobia is the fear of confined spaces. It can be triggered by many situations or stimuli, including elevators, especially when crowded to capacity, windowless rooms, and hotel rooms with closed doors and sealed windows. Even bedrooms wit ...

schizophrenia Schizophrenia is a mental disorder characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations (typically hearing voices), delusions, and disorganized thinking. Other symptoms include social wit ...

, or low

pain tolerance Pain tolerance is the maximum level of pain that a person is able to tolerate. Pain tolerance is distinct from pain threshold (the point at which pain begins to be felt). Additionally, patients with obstructive sleep apnea are usually considered poor candidates due to problems with oxygenation, ventilation, and a potentially difficult airway.Wong, Jaclyn, Kong, Amy, Lam, Sau, Woo, Peter. High-Flow Nasal Oxygen in Patient With Obstructive Sleep Apnea Undergoing Awake Craniotomy: A Case Report. ''A&A Case Reports.'' 2017;9(12):353-356. doi:10.1213/XAA.0000000000000615.

References

{{reflist, 30em Neurosurgical procedures