The surgical technique for resection of glioma in the functional brain area under arousal is a hot and difficult issue in the field of neurosurgery at home and abroad. This guideline is based on the “Expert Consensus on Surgical Techniques for Resection of Glioma in Functional Brain Area under Arousal” published in 2013, and has been improved based on new research results and modifications proposed by experts in the past year. In order to facilitate the reader’s understanding and to better carry out surgical work, this guideline refers to the evidence-based medicine and the recommended level of classification in the Chinese Guidelines for the Diagnosis and Treatment of Gliomas of the Central Nervous System (2012).
1. Anatomy of functional areas
1.1 Sensory areas of sensory-motor related functional brain regions.
The primary sensory area is located in the postcentral gyrus between the central sulcus and the postcentral sulcus. Motor areas mainly include the primary motor area (M1), the premotor area (PMA) and the supplementary motor area (SMA).
(1) Primary motor area is located in the precentral gyrus between the central sulcus and the precentral sulcus, which is wide at the top and narrow at the bottom and anatomically discontinuous (the middle frontal gyrus divides it into two parts: upper and lower).
(2) Premotor area: located on the lateral side of the frontal lobe, occupying part of the superior frontal gyrus, middle frontal gyrus and precentral gyrus, like the primary motor area, the premotor area is also wide at the top and narrow at the bottom.
③Auxiliary motor area: located in the anterior part of the paracentral lobule and the posterior part of the medial side of the superior frontal gyrus, above the premotor area; there are some differences among individuals, and the function can be divided into two parts: anterior and posterior.
1.2 Language related functional brain areas
1.2.1 Broca’s area.
Broca’s area is a motor language center, which mainly includes the posterior part of the cover and delta of the inferior frontal gyrus of the dominant hemisphere, and the posterior part of the BA44 and BA45 areas in terms of cellular architecture.The main functions of Broca’s area are language formation, initiation and coordination of coordinated movements of the articulatory organs.The two parts of Broca’s area play different roles in language comprehension and production, and it is generally believed that the delta is related to semantics and the cover is related to phonology. Injuries to the Broca’s area usually cause motor aphasia, i.e., impaired speech expression.
1.2.2 Wernicke’s area.
The sensory language center, which is more diffuse in distribution, has no clear anatomical boundaries (roughly corresponding to the posterior 1/3 of the superior temporal gyrus of the dominant hemisphere). Wernicke’s area is mainly located in areas BA22, BA39, BA40, and BA37, and is mainly involved in sound discrimination and comprehension. sensory aphasia, also called Wernicke’s aphasia, occurs after damage to Wernicke’s area, i.e., speech comprehension disorder, and the speech it produces is also difficult to be understood.
1.2.3 Other regions.
The distribution of language-related brain regions is not limited to the classical Broca’s area and Wernicke’s area; their distribution is quite extensive and varies greatly between individuals. The following regions are mainly involved: the posterior part of the inferior frontal gyrus (Broca’s area), the posterior part of the medial superior frontal gyrus (SMA area), the posterior part of the superior and middle frontal gyrus (premotor area), the temporal lobe and the temporo-parieto-occipital junction area of the dominant hemisphere. In addition, for native speakers of Chinese, the nondominant hemisphere is involved in higher language functions such as phonology, intonation, and rhyme.
1.3 Anatomy of motor and language subcortical conduction tracts
1.3.1 Corticospinal tracts.
It is a motor-related subcortical conduction bundle that originates from the pyramidal cells of layer V in many areas of the cerebral cortex (mainly BA4, BA6, BA3, BA1, BA2, etc.); the thick fibers are the axons of the large pyramidal cells (Betz cells) in the deep part of layer V in area 4; while the fine fibers emanate from the small neurons in layer Va. This bundle descends through the anterior part of the hind limb of the internal capsule.
1.3.2 Language-related subcortical conduction bundles.
Several important white matter pathways associated with language in the brain are.
(1) Arch bundle: It is part of the superior longitudinal bundle and originates from the caudal part of the superior temporal gyrus and bypasses the lateral fissure. It travels anteroposteriorly in the superior lateral nucleus and insula, lateral to the internal capsule, and terminates with the other superior longitudinal tracts in the dorsal part of the prefrontal lobe (areas BA8 and 46). The main function of the arcuate fasciculus is to conduct signals of the phonological system.
(ii) Inferior occipitofrontal fasciculus: the inferior occipitofrontal fasciculus starts from the posterior lateral region of the occipital and temporal lobes, travels forward over the lateral lateral wall of the temporal horn of the lateral ventricle, passes through the anterior base of the medial external capsule of the insula, and reaches the dorsal lateral part of the orbitofrontal and prefrontal lobes, and its function is to participate in the transmission of the semantic system.
(iii) Inferior cingulate bundle: The mouth-side portion of the medial inferior cingulate bundle is located in the lateral wall of the frontal horn (deep in Broca’s area) and contains fibers that project from the cingulate gyrus and supplementary motor areas to the caudate nucleus. Injury to this conduction bundle usually results in transcortical motor aphasia. (iv) Frontoparietal speech loop: as the final pathway for articulation, it is usually located in the oromotor area and deep in the anterior insula, and electrical stimulation induces articulatory deficits.
1.4 New perspectives on the localization of functional areas Many current studies have shown that
The distribution of functional areas may not be grouped, i.e., a certain cortical area is responsible for only one function alone, e.g., Broca’s area is responsible for motor speech, while Wernicke’s area is responsible for sensory speech functions. Modern cognitive neuroscience considers the distribution of functional areas of the brain as a highly complex networked structure – BrainConnectivity – in which the parts are relatively independent and highly integrated, and all cognitive functions are the result of interactions within this vast network. All cognitive functions are the result of interactions within this vast network – the connectome. The implications of this network structure cognition for neurosurgery are as follows.
(i) Damage at any point in the functional network may cause abnormalities in some cognitive function, such as language, memory, etc.
(ii) Damage limited to a single location may cause damage to multiple networks associated with it, resulting in abnormalities in multiple cognitive functions.
③If other parts of the network can compensate or reorganize their functions, an injury at a particular location may cause only minor or transient functional abnormalities.
(iv) Specific anatomical locations may have relative (not absolute) specificity for a particular cognitive function. Relatively independent network structures that are generally considered to be clinically relevant are: the language network, which is dominated by the left lateral perisylvian region; the spatial recognition network, which is dominated by the right frontoparietal region; the face and object recognition network in the temporo-occipital region; the limbic system, which stores long-term memory; and the prefrontal network, which is related to attention and behavior. The structure of each of the above networks varies greatly among individuals.
2. Indications and contraindications
2.1 Indications
(1) Glioma involving functional areas of the brain.
②Age is usually not less than 14 years old (depending on the patient’s cognitive and self-control ability).
③No clear history of psychiatric disorders or severe psychiatric symptoms.
④Conscious, with basically normal cognitive function, and able to cooperate with the assigned tasks before surgery.
⑤ Those who voluntarily undergo wake up anesthesia surgery.
2.2 Contraindications
①Patients younger than 14 years old (relative contraindication) or with mental developmental delay.
② Clear history of psychiatric disorders.
③Poor cognitive function and inability to cooperate with the assigned task before surgery.
④Severe cardiac, pulmonary, hepatic and renal dysfunction that precludes surgery.
⑤ Other contraindications that make them unsuitable for neurosurgical craniotomy.
⑥Those who refuse to accept arousal anesthesia for surgery.
3.Preoperative examination and evaluation
3.1 Preoperative multimodal imaging examination
Preoperative neuroimaging can help clinicians understand the scope of the lesion and its relationship with the surrounding functional structures, correctly determine the relative boundary between the lesion and the functional brain area, and facilitate the development of an individualized optimal surgical plan.
Highly recommended: T1, T2, Flair, T1 enhancement examinations.
Recommended: BOLD, DTI, PWI examination.
May recommend: MRA, MRV, MRS, PET-CT, MEG examination.
3.1.1 Routine preoperative imaging examinations.
①3D-T1, T2, T2-Flair, T1-enhanced images: the extent of the lesion, edema and malignancy can be determined.
②Magnetic resonance (arterial) angiography (TOF): the relationship between the lesion and the peripheral arteries can be observed.
③Magnetic resonance (venous) angiography (MRV): to understand the relationship between the lesion and the thick draining veins.
④Magnetic resonance spectroscopy imaging (MRS): to understand the metabolism of the lesion, which is helpful for differential diagnosis and determination of the malignancy of the tumor (grade IV evidence).
⑤ Magnetic resonance perfusion imaging (PWI): to understand the perfusion of the lesion and the surrounding area (level IV evidence).
3.1.2 Blood oxygen level-dependent functional magnetic resonance (BOLD-fMRI).
This technique is non-invasive, non-radioactive, reproducible, and has a high temporal and spatial resolution; it can be processed to show functional area activation maps. It can be used for preoperative sensory-motor area, speech area localization and supporting evidence for dominant hemisphere lateralization.
Task-based functional MRI (Level III evidence): Modular design (Blockdesign) scanning tasks are usually used.
① Motor area activation detection task: alternating finger movements (or dorsiflexion and extension of the foot) with a rest module. The motor task usually uses finger open grip movements or specified sequences of opposite finger movements or dorsiflexion and extension movements to localize the patient’s hand and foot motor sensory areas. The general modular design has a duration of not less than 20 s for each group of movement and rest modules, and the interval between adjacent task modules should not be longer than 128 s.
②Language area activation detection task: alternate between language tasks and rests. The language task usually uses picture naming or word association, verb generation, sentence judgment, etc. Different forms of language tasks can be selected according to each patient’s literacy and language habits as well as the target area. The usual modular design has a task module and baseline module time of not less than 20s, and the interval between adjacent task modules must not be longer than 128s.
Resting-state functional connectivity imaging: requires the subject to be awake, eyes closed, and lying quietly on the MRI bed without cooperation in completing any tasks. It requires post image processing and is currently mostly used to localize the patient’s sensorimotor areas and to study the mechanisms of abnormal brain functional networks in neurological diseases.
3.1.3 Diffusion tensor imaging (DTI) and fiber bundle tracking (Level IV evidence).
Images are usually acquired using 1.5T or 3.0T MRI equipment with diffusion-weighted spin-echo planar echo (spin-echodiffusion-weighted EPI) imaging with a voxel size of 2mm × 2mm × 2mm and more than 12 directions. The white matter fibers commonly displayed by DTI techniques include: projection fibers (corticospinal tract, corticobulbar tract, and thalamic radiation), liaison fibers (superior longitudinal tract, inferior longitudinal tract, and inferior occipitofrontal tract), and joint fibers (corpus callosum).
3.1.4 Other functional imaging techniques.
①Positron emission tomography (PET): application of radionuclides as tracers to localize important functional areas by measuring changes in relevant local cerebral blood flow with low spatial resolution.
②Magnetoencephalography (MEG) and magnetogenic imaging (MSI): non-invasive examination methods to localize functional cortices by monitoring the magnetic field changes generated during nerve cell excitation. It can be used to localize motor and speech areas.
3.2 Preoperative neurological function assessment
The purpose of applying objective and widely accepted neuropsychological scales is not only to evaluate the patient’s functional status, but also to enable the surgeon to understand the degree of impact of the lesion on the patient and to provide a basis for the development of the surgical plan and postoperative rehabilitation program. Neuropsychological tests should apply standardized materials and experimental methods, and the scales applied must have normal range values, high reproducibility, short duration (30-40 min) and detectable changes in cognitive function over time.
Highly recommended: KPS, Edinburgh Sharpshooter, Simple Mental Status Scale (MMSE).
Recommended: Wechsler Adult/Childhood Intelligence Test, Western Aphasia Battery (WAB) Chinese version, BOLD-fMRI Functional Lateralization Index, Line Segment Equipartition Test.
May recommend: WADA test, China Rehabilitation Research Center Aphasia Examination (CRRCAE), Montreal Cognitive Assessment Scale (MoCA), Activities of Daily Living score (ADL), Depression Self-Rating Scale (SDS), Anxiety Self-Rating Scale (SAS), Symptom Self-Rating Scale (SDL90).
3.3 Preoperative education
After preoperative neuroimaging and neuropsychological assessments, the surgical plan was developed with comprehensive consideration and intraoperative functional monitoring tasks were selected. The surgeon, anesthesiologist and neuropsychologist will explain to the patient and family members in detail about general anesthesia arousal surgery.
①The procedure of general anesthesia arousal surgery.
②The importance of functional monitoring techniques under intraoperative arousal for localization and protection of functional brain areas.
③Potential risks and complications of surgery and anesthesia.
④Possible discomfort during surgery, such as dry mouth, holding urine, chills, and head discomfort.
⑤ Patient instruction and preoperative simulation exercises are given according to the tasks to be accomplished during surgery. After the patient and family understand the risks and significance of general anesthesia wake up surgery, if they voluntarily accept the general anesthesia intraoperative wake up surgery, they sign the informed consent form for general anesthesia intraoperative wake up surgery.
4.Operating room preparation
4.1 Incision design
The incision should be designed according to the location of the lesion and the location of the functional areas, and in principle should include the lesion and the important functional brain areas it involves (monitoring target areas). Additional factors to be considered.
① Expose the lesion and surrounding functional areas to facilitate intraoperative monitoring and functional localization protection.
②Tumors with high recurrence rate (e.g. glioma) should be considered for possible secondary surgery.
③Inter-individual variability in the distribution of functional areas.
④Structural factors such as subcutaneous arteries, venous sinuses, hairline and other conventional factors that need to be considered.
4.2 Position
①The lateral position is often adopted, with the head fixed in a head frame and the head slightly tilted back for reintubation.
② If the supine position is adopted, close attention should be paid to prevent the occurrence of intraoperative aspiration. The position chosen should ensure the patient’s intraoperative comfort and use a thermal blanket after positioning to reduce the patient’s chills after awakening and the increase in intracranial pressure caused by it.
4.3 Disinfection of towels
Place a support frame above the patient’s shoulder and pay attention to isolating the operative field and leaving an intraoperative observation area when spreading the sheet. The patient’s face and hands should be clearly visible to the intraoperative monitor. If speech naming monitoring is required, a screen can be placed in the patient’s field of view, so that the center of the patient’s field of view coincides with the center of the screen as much as possible.
4.4 Neuronavigation
The structural and functional image information obtained preoperatively is incorporated into the neuronavigation to register the reference frame and reference points (refer to the instructions for use of that brand model of navigator for registration methods). The body projection of the lesion can be marked with the aid of neuronavigation, and the incision can be adjusted appropriately.
4.5 Other matters
①Play soft music during the preoperative preparation period and non-operative task period to relieve the patient’s tension.
②When myopic patients need to perform intraoperative picture naming tasks, wear glasses or draw the screen closer to ensure that the patient can see clear images.
③Patients with a history of epilepsy should be given antiepileptic drugs preoperatively and intraoperatively.
5.Wake up anesthesia technique
Strongly recommended: None for now.
Recommended: Intravenous anesthetic drug target-controlled infusion technique combined with local block anesthesia (ventilation method is recommended to use double-tube laryngeal mask, and nasopharyngeal tube placement or oropharyngeal ventilation channel placement can also be used).
It is recommended to use double tube laryngeal mask placement and intravenous anesthetic drug target-controlled infusion technique combined with local block anesthesia. Intravenous target-controlled infusion has good controllability, easy to adjust the depth of anesthesia, quick and complete recovery of consciousness after stopping the drug, and low adverse effects. The laryngeal mask is less irritating, the intraoperative repositioning is less demanding, easier than tracheal intubation, facilitates airway management, and can effectively avoid intraoperative hypercapnia and misaspiration. To avoid patient pain, local infiltration anesthesia was applied to the cephalic frame fixation staples and flap incision, base and dura mater, along with auxiliary scalp nerve block, which facilitated the patient’s cooperation in a painless and awake state to complete the intraoperative tasks.
5.1 Anesthetic arousal process using laryngeal mask for airway control
① Preoperative sodium phenobarbital and other sedative drugs that may affect intraoperative wakefulness are not recommended; atropine is not recommended. Intraoperative intravenous long tonic 0.01~0.02mg/kg can be injected, which has good anticholinergic effect, insignificant dry mouth effect, and no cardiovascular reaction.
②Induction of anesthesia: propofol target-controlled infusion with an initial plasma target concentration of 4~5μg/ml and intravenous infusion of remifentanil [target-controlled infusion effect chamber concentration of 3~4ng/ml or continuous intravenous pumping of 0.1~0.2μg/(kg?min)], followed by placement of a laryngeal mask after the patient’s consciousness disappears.
③Anesthesia maintenance was still done with propofol target-controlled infusion with a target concentration of 3~5μg/ml, without inotropic drugs; SIMV ventilation mode was used to control respiration.
④Local infiltration anesthesia was performed with 0.25% ropivacaine or bupivacaine at the scalp incision and fixed frame head nail.
⑤ A cutaneous nerve block of the head is recommended to facilitate analgesia during wakefulness and to reduce the dose of analgesic drugs. The nerves that can be blocked are: the greater occipital nerve, the lesser occipital nerve, the auriculotemporal nerve, and the supraorbital nerve.
(6) The application of BIS and Narcotrend is recommended to monitor the depth of anesthesia of the patient.
(vii) The dura was anesthetized with local infiltration of brain cotton containing 2% lidocaine, while the target-controlled concentration of propofol was gradually decreased to 0.8~1.2 μg/ml according to the waking condition.
(8) After the patient is awake, the mask is removed; the degree of arousal is assessed, the drug concentration is individually adjusted, and appropriate sedation is maintained before the dura is cut. Dexmedetomidine 0.1~0.2μg/(kg?h) continuous pump sedation is recommended during the waking period, which can be aroused with light respiratory depression.
⑨ After tumor resection, increase the target concentration of propofol to (3~5μg/ml) and the target concentration of remifentanil to (3~5ng/ml), reposition the laryngeal mask, and control breathing until the end of surgery. Alternatively, propofol was used to maintain the sedation concentration until the end of the procedure.
5.2 Precautions
① When a patient has an intraoperative seizure, immediately use saline or ice water solution of Ringer’s solution to flush the local cortex to cool down. If seizures persist, anesthesia should be deepened quickly and breathing should be controlled according to the situation.
② During craniotomy, selective use of anesthetic drugs when the effect of scalp block is unsatisfactory: remifentanil is the drug of choice for strong analgesia as well as mild sedation; propofol is the second choice and is used only when the patient shows significant anxiety and agitation. Note: The combined application of remifentanil and propofol may significantly depress respiration while affecting circulatory stability.
③ Do not cut the dura mater before removing the mask, and control circulatory fluctuations by vasoactive drugs and beta-blockers up to 20% of the basal value. In patients with high intracranial tension, mannitol should be started at the time of craniotomy to avoid brain swelling or brain bulge during the patient’s laryngeal mask removal. ④ Intraoperative partial pressure of end-breath CO2 should be controlled at about 30 mmHg, but not more than 50 mmHg.
6.Intraoperative operation technique
6.1 Craniotomy procedure
Nerve block anesthesia and local infiltration anesthesia of the incision in the head surgery area are done, and it is recommended that the local anesthetic agent should be long-acting low toxicity roquacaine. The incisional anesthesia covers the skin of the operative field, subcutaneously to the periosteum, including the base of the flap. The dura is covered with a 2% lidocaine infiltrated cotton pad for 15 min, the dura is suspended around it (without excessive traction), and the epidural is thoroughly hemostatic. The anesthesiologist is informed to prepare the patient for arousal.
6.2 Intraoperative imaging techniques
Highly recommended: None at this time.
Recommended: neuronavigation system.
May be recommended: intraoperative MRI, intraoperative ultrasound, etc. may be used.
6.2.1 Neuronavigation (multiple concordance level III evidence).
Use preoperatively acquired structural and functional images to assist in determining surgical access and localizing target areas. The use of intraoperative navigation to identify important anatomical structures such as the central sulcus facilitates shorter intraoperative functional monitoring. Drift is currently the main problem of intraoperative navigation, which is divided into two categories: systematic drift caused by equipment errors during registration and structural drift caused by brain tissue displacement.
6.2.2 Intraoperative MRI.
Intraoperative MRI can correct brain shifts, update navigation in real time, determine whether tumors remain and show the positional relationship between functional areas, fiber tracts and residual lesions, and its help to improve the extent of glioma resection (multiple level II evidence, recommended).
The integration of both arousal anesthesia and intraoperative MRI techniques helps to maximize the safe resection of functional area gliomas (multiple Level IV evidence, recommended). There are the following considerations for arousal anesthesia in the intraoperative MRI setting.
(i) Equipment or materials that cannot be evacuated intraoperatively are guaranteed to be MRI compatible (e.g., head frame, navigation frame, and subcutaneous needle electrodes, gauze, etc.).
②MRI should be laminar flowed for half an hour prior to scanning.
③ Intraoperative MRI environment for wake-up anesthesia requires the selection of different towel laying methods according to different wake-up protocols.
At present, the commonly used wake-up anesthesia protocols internationally include MAC (MonitoredAnesthesiaCare) protocol and AAA (Asleep-Awake-Asleep) protocol. AAA protocol, i.e., the laryngeal mask placement protocol, has advantages such as simple airway management, but its operation is complicated, and it is difficult to reposition the ventilation device and requires higher postural requirements. The MAC protocol has the advantages of simple operation and easy wake-up at any time, but it is difficult to manage the airway in the intraoperative magnetic resonance environment. The localized towel method can effectively solve the challenges of airway management and surgical asepsis. The procedure is as follows: first, the scalp and dura mater are simply sutured, a sterile sheet of about 60 cm × 60 cm is covered over the operative field, and then a sterile adhesive film of 80 cm × 80 cm is used to fix it, and all the excess laying towels around the operative field are cut off, and only a 20-30 cm area around the operative field is retained, which allows the patient’s face to be revealed and facilitates airway management. After scanning, the local mucosa and tissues were removed, and the tissues were redone according to the cranial surgery routine to continue the surgery.
6.2.3 Intraoperative ultrasound.
It is simple to operate, good in real time, and can guide the surgeon in real time through the bone window to determine the localization of the lesion and its degree of resection, which is easy to promote. The use of high-frequency Doppler ultrasound can also provide both peri-lesion and internal blood flow conditions. Ultrasonography allows observation of tumor perfusion and enhancement characteristics, which can be helpful in identifying the border. Its disadvantage is that the image is easily affected by the cut surface, air, edema band, etc.
6.3 Intraoperative brain function localization techniques
Strongly recommended: direct electrical stimulation to localize functional areas of the cortex (level II evidence; multiple consistent level III evidence).
Recommended: cortical somatosensory evoked potentials to localize the central sulcus; motor evoked potentials to monitor motor areas; direct electrical stimulation to localize subcortical functional structures; neuronavigation combined with preoperative functional magnetic resonance.
6.3.1 Principle of direct electrical stimulation.
By applying an appropriate current (biphasic stimulation square wave) to the cortical and subcortical structures, the local neurons and the neural tissue of their conduction bundles are depolarized, causing excitation or inhibition of the local neural tissue, which is manifested as excitation or inhibition of the corresponding function of the patient.
6.3.2 Direct electrical stimulation stimulation methods.
① A bipolar electrical nerve stimulator (bipolar interval 5 mm) is used. The stimulation waveform is a biphasic square wave, the recommended stimulation frequency is 60 Hz, the wave width is 1 ms, and the continuous stimulation mode is used.
②The most appropriate stimulation current intensity can be determined according to the EEG monitoring of the emergence of post-discharge and the generation of neurological functional activity. Usually start from 1mA and gradually increase the stimulation current intensity in the range of 0.5~1mA until a positive response is induced or post-discharge is detected by EEG. The stimulation current should not exceed 8mA in motor areas and 15mA in other areas. subcortical stimulation usually requires 1-2mA more than cortical stimulation current.
(iii) Stimulate each target area (exposed cortex) sequentially according to a certain pattern. Stimulate each target area at least 3 times in a cycle. The duration of each stimulation is approximately 1 s for motor and sensory tasks and 4 s for language and other cognitive tasks (depending on the task, up to 6 s).
④Excision of the lesion can be accompanied by subcortical electrical stimulation to localize important subcortical conduction fiber bundles as appropriate.
⑤ Note: The site where the seizure was induced should not be stimulated with the same amount of current; the same site should not be stimulated 2 times in a row.
6.3.3 Intraoperative observation.
A neuropsychologist or a full-time nurse should closely observe the patient’s response during the whole stimulation process to determine whether the patient has a positive response and the corresponding type of positive response. Two or more positive presentations in three stimulations at the same location are considered positive response areas. The observer also needs to closely observe the patient for seizures and take immediate measures to control them.
6.3.4 Labeling and recording.
A sterile label is used to mark the location of the area of stimulation where a positive reaction occurs, and the positive reaction manifestation is also recorded; the negative reaction area only needs to be recorded with location information and does not need to be marked.
6.3.5 Intraoperative tasks and positive performance.
Recommended: motor, sensory, counting, picture naming.
May be recommended: calculation, reading, line segment equipartition.
Motor area monitoring.
① Positive motor area manifestations are involuntary movements of muscles in the corresponding parts of the contralateral limb or face, while electromyographic activity can be recorded; electrical stimulation of the premotor area or supplementary motor area may cause complex movements.
②The important subcortical structures in the motor area that need to be monitored and protected are the pyramidal bundles.
Sensory area monitoring.
Positive sensory area manifests as abnormal sensation in the contralateral limb or head in a pulsatile manner, mostly in the form of numbness; stimulation of the sensory area may also sometimes cause limb movement.
Speech area monitoring.
The recommended language tasks are: counting and picture naming.
①Counting task: The patient counts from 1 to 10 and keeps repeating it during the electrical stimulation after waking up. If the patient has an interruption in counting while the electrical stimulation is in progress and resumes rapidly after stopping the stimulation, the stimulation area is initially defined as the motor speech center or the motor area associated with the facial muscles.
②Naming task: A set (>30) of black and white pictures with common objects drawn on them is presented to the patient in its entirety through the screen. The patient names the pictures immediately after seeing the slide and says “This is… (name of object)…”. At least one picture was intervened between each 2 stimulation sessions. During the electrical stimulation, the abnormal performance of the patient suggested that the area was a variety of relevant language centers. Picture materials are recommended to use pictures of objects that have been standardized for Chinese language.
(③) Subcortical monitoring: The important structures in the language area that need to be monitored and protected are the arcuate fasciculus, suboccipital frontal fasciculus, and subcingulate fasciculus.
7.Lesion removal strategy
On the premise of preserving the important functional structures, choose the appropriate surgical access to remove the lesion as much as possible. At the same time, attention should be paid to protect the normal arteries and important drainage vessels on the brain surface. The resection process can be alternated with subcortical electrical stimulation to identify important subcortical functional structures and protect them. After removal of the lesion, intraoperative magnetic resonance scanning, intraoperative ultrasound or fluorescence imaging can be applied to observe whether there is residual lesion.
8. Prognostic evaluation and follow-up
It is strongly recommended to perform enhanced MRI examination within 24-48h after surgery to evaluate the extent of tumor resection. It is recommended to evaluate the KPS score, speech function, motor function and quality of life of patients at 1-3d, 3 weeks, 3 months and 12 months after surgery, respectively. The evaluation process is recommended to use a combination of neuroimaging and behavioral scales.
The key to glioma surgery is to maximize tumor removal while preserving function. Maximum safe tumor removal is strongly recommended for primary high-grade (WHO grade III-IV) or low-grade (WHO grade II) gliomas that are confined to the lobes of the brain. Through precise and reliable individualized localization of functional areas, maximum resection of the lesion while monitoring and protecting the patient’s vital functions can effectively avoid the occurrence of permanent postoperative neurological impairment and significantly improve the patient’s postoperative quality of survival. Intraoperative subcortical arousal and direct subcortical electrical stimulation techniques are considered to be the “gold standard” for functional brain localization.