Awake craniotomy is a neurosurgical technique and type of

craniotomy A craniotomy is a surgery, surgical operation in which a bone flap is temporarily removed from the Human skull, skull to access the Human brain, brain. Craniotomies are often critical operations, performed on patients who are suffering from brain ...

that allows a surgeon to remove a

brain tumor A brain tumor (sometimes referred to as brain cancer) occurs when a group of cells within the Human brain, brain turn cancerous and grow out of control, creating a mass. There are two main types of tumors: malignant (cancerous) tumors and benign ...

while the patient is awake to avoid

brain damage Brain injury (BI) is the destruction or degeneration of brain cells. Brain injuries occur due to a wide range of internal and external factors. In general, brain damage refers to significant, undiscriminating trauma-induced damage. A common ...

. 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,

glioma A glioma is a type of primary tumor that starts in the glial cells of the brain or spinal cord. They are malignant but some are extremely slow to develop. Gliomas comprise about 30% of all brain and central nervous system tumors and 80% of ...

s, and brain metastases. It can also be used for

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

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 type of neurostimulation therapy in which an implantable pulse generator is stereotactic surgery, surgically implanted subcutaneous tissue, below the skin of the chest and connected by Lead (electronics), leads ...

placement, or for pallidotomy. 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 anti-anxiety 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 anxie ...

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 medically induced loss of consciousness that renders a patient unarousable even by painful stimuli. It is achieved through medications, which can be injected or inhaled, often with an analgesi ...

. The anesthesiologist will then use

local anesthetic A local anesthetic (LA) is a medication that causes absence of all sensation (including pain) in a specific body part without loss of consciousness, providing local anesthesia, as opposed to a general anesthetic, which eliminates all sensati ...

s like

lidocaine Lidocaine, also known as lignocaine and sold under the brand name Xylocaine among others, is a local anesthetic of the amino amide type. It is also used to treat ventricular tachycardia and ventricular fibrillation. When used for local anae ...

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

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 In anatomy, the meninges (; meninx ; ) are the three membranes that envelop the brain and spinal cord. In mammals, the meninges are the dura mater, the arachnoid mater, and the pia mater. Cerebrospinal fluid is located in the subarachnoid spac ...

, 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 may ask them questions. A speech and language pathologist and/or a

neuropsychologist Neuropsychology is a branch of psychology concerned with how a person's cognition and behavior are related to the brain and the rest of the nervous system. Professionals in this branch of psychology focus on how injuries or illnesses of the brai ...

monitor the patient carefully while the patient performs different types of language/other cognitive tasks. The golden standard for intraoperative tasks is object naming, but there are a number of different tasks that can be used during awake surgery. 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 A seizure is a sudden, brief disruption of brain activity caused by abnormal, excessive, or synchronous neuronal firing. Depending on the regions of the brain involved, seizures can lead to changes in movement, sensation, behavior, awareness, o ...

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

hypertension Hypertension, also known as high blood pressure, is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not cause symptoms i ...

hypotension Hypotension, also known as low blood pressure, is a cardiovascular condition characterized by abnormally reduced blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood and is ...

, 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, ...

stroke Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...

or air embolism, and death. Seizures are the most common complication. Awake surgery in gliomas is known to cause postoperative language and other cognitive impairments, however the frequency and severity is not well established due to e.g. differences in patient selection, test methods and how deficits are defined. In the sub-acute phase (1-10 days postoperatively) the difficulties may be quite severe, but gradual recovery is expected.

Contraindications

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

anxiety disorder Anxiety disorders are a group of mental disorders characterized by significant and uncontrollable feelings of anxiety and fear such that a person's social, occupational, and personal functions are significantly impaired. Anxiety may cause phys ...

s, claustrophobia,

schizophrenia Schizophrenia () is a mental disorder characterized variously by hallucinations (typically, Auditory hallucination#Schizophrenia, hearing voices), delusions, thought disorder, disorganized thinking and behavior, and Reduced affect display, f ...

, or low pain tolerance are poor candidates for an awake surgery because any treatment of a psychological crisis would harm the procedure and could harm the patient. 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