Surgical resection of gliomas in the dominant inferior frontal gyrus: Consecutive case series and anatomy review of Broca's area.

INTRODUCTION: There is a general lack of consensus on both anatomic definition and function of Broca's area, often localized to the pars triangularis (pT) and pars opercularis (pOp) of the left inferior frontal gyrus (IFG). Given the belief that this region plays a critical role in expressive language functions, resective surgery is often avoided to preserve function. However, the putative role of Broca's area in speech production has been recently challenged. The current study aims to investigate the plausibility of glioma resection and neurological outcomes in "Broca's area". METHODS: We report a single-surgeon, consecutive case series feasibility study describing the resection of gliomas within the IFG. Presentation, mapping, functional outcome, and extent of resection variables were considered for analysis. RESULTS: All included patients had tumors located in the traditional "Broca's area", eight (53.33 %) additionally extending into the insular and subinsular regions. All patients except for one, presented with speech-language deficits preoperatively. Awake brain surgery for tumor resection with direct cortical and subcortical stimulation and intraoperative neuropsychological evaluation was carried out in all individuals. During stimulation, positive speech-language sites within the IFG were identified in ten patients. Two patients (13.33 %) experienced a decline in naming during intraoperative cognitive monitoring and thirteen (86.66 %) had a stable performance throughout surgery. At two-week follow-up, all patients had recovery of language functions compared to initial presentation. Overall extent of resection (EOR) was 60.35 % ( ± 29.60) with residual tumor being the greatest within the insular and subinsular areas. EOR was stratified in anatomical regions within the IFG, being the pOr the area with the greatest EOR (97.4 %), followed by the pT (84.1 %), pOp (83.8 %), and vPMC (80 %). CONCLUSION: The belief that Broca's area is not safe to resect is challenged. Adequate mapping and careful patient selection allow maximum safe resection of tumors located in the traditional "Broca's area", with low risk of postoperative morbidity.

Anesthetic Management of Awake Craniotomy for Resection of the Language and Motor Cortex Vascular Malformations.

BACKGROUND: Although the safety and feasibility of awake craniotomy are well established for epilepsy and brain tumor surgery, its application for resection of vascular lesions, including arteriovenous malformations (AVMs) and cavernomas, is still limited. Apart from the usual challenges of awake craniotomy, vascular lesions pose several additional problems. Our goal is to determine the safety and practicality of awake craniotomy in patients with cerebral vascular malformations located near the eloquent areas, using a refined anesthetic protocol. METHODS: A retrospective case series was performed on 7 patients who underwent awake craniotomy for resection of AVMs or cavernomas located in the eloquent language and motor areas. Our protocol consisted of achieving deep sedation, without a definitive airway, using a combination of propofol, dexmedetomidine, and remifentanil/fentanyl during scalp block placement and surgical exposure, then transitioning to a wakeful state during the resection. RESULTS: Six patients had intracranial AVMs, and 1 patient had a cavernoma. Six patients had complete resection; however, 1 patient underwent repeat awake craniotomy for residual AVM nidus. The patients tolerated the resection under continuous awake neurologic and neurophysiologic testing without significant perioperative complications or the need to convert to general anesthesia with a definitive airway. CONCLUSIONS: Awake craniotomy for excision of intracranial vascular malformations located near the eloquent areas, in carefully selected patients, can facilitate resection by allowing close neuromonitoring and direct functional assessment. A balanced combination of sedative and analgesic medications can provide both adequate sedation and rapid wakeup, facilitating the necessary patient interaction and tolerance of the procedure.

The cortical organization of language: distilling human connectome insights for supratentorial neurosurgery.

Connectomics is the production and study of detailed "connection" maps within the nervous system. With unprecedented advances in imaging and high-performance computing, the construction of individualized connectomes for routine neurosurgical use is on the horizon. Multiple projects, including the Human Connectome Project (HCP), have unraveled new and exciting data describing the functional and structural connectivity of the brain. However, the abstraction from much of these data to clinical relevance remains elusive. In the context of preserving neurological function after supratentorial surgery, abstracting surgically salient points from the vast computational data in connectomics is of paramount importance. Herein, the authors discuss four interesting observations from the HCP data that have surgical relevance, with an emphasis on the cortical organization of language: 1) the existence of a motor speech area outside of Broca's area, 2) the eloquence of the frontal aslant tract, 3) the explanation of the medial frontal cognitive control networks, and 4) the establishment of the second ventral stream of language processing. From these connectome observations, the authors discuss the anatomical basis of their insights as well as relevant clinical applications. Together, these observations provide a firm platform for neurosurgeons to advance their knowledge of the cortical networks involved in language and to ultimately improve surgical outcomes. It is hoped that this report encourages neurosurgeons to explore new vistas in connectome-based neurosurgery.

Intraparenchymal Epidermoid Cyst Close to Broca Area-Awake Craniotomy and Gross Total Resection.

BACKGROUND: Epidermoid tumors, or epidermoid cysts (ECs), are benign, slow-growing, congenital, and rare lesions that represent approximately 0.2%-1.8% of all intracranial tumors. Intraparenchymal ECs are very rare lesions that may account for 1.5% of all intracranial epidermoid tumors; frontal lobe involvement is found in 39.2% of intraparenchymal ECs. We present a case using awake craniotomy to achieve maximal safe gross total resection of a rare intraparenchymal EC close to Broca area in a bilingual patient. CASE DESCRIPTION: A 45-year-old man presented with a generalized seizure episode. He was initially treated with levetiracetam, which led to renal failure. Imaging findings demonstrated an intraparenchymal left frontal EC with peripheral coarse calcifications at Broca area. As the patient was bilingual and had a normal neurologic examination, we performed a left frontal awake craniotomy under local anesthesia so as to map both languages, using the motor task and a test for language monitoring, alternating a naming task in Portuguese and English and a semantic task in Portuguese. A gross total resection was achieved with no neurologic deficits. Histopathologic examination confirmed the diagnosis of an epidermoid cyst. After 1 year, the patient is still seizure-free. CONCLUSIONS: Awake surgery proved to be a useful tool for complete resection of the capsule even in a very eloquent language area. In multilingual patients with benign intra-axial lesions, intraoperative mapping should be performed for all the languages in which the patient is fluent to avoid postoperative neurologic deficits.

Language supplementary motor area syndrome correlated with dynamic changes in perioperative task-based functional MRI activations: case report.

Supplementary motor area (SMA) syndrome is well known; however, the mechanism underlying recovery from language SMA syndrome is unclear. Herein the authors report the case of a right-handed woman with speech aphasia following resection of an oligodendroglioma located in the anterior aspect of the left superior frontal gyrus. The patient exhibited language SMA syndrome, and functional MRI (fMRI) findings 12 days postoperatively demonstrated a complete shift of blood oxygen level-dependent (BOLD) activation to the contralateral right language SMA/pre-SMA as well as coequal activation and an increased volume of activation in the left Broca's area and the right Broca's homolog. The authors provide, to the best of their knowledge, the first description of dynamic changes in task-based hemispheric language BOLD fMRI activations across the preoperative, immediate postoperative, and more distant postoperative settings associated with the development and subsequent complete resolution of the clinical language SMA syndrome.

Impact of connectivity between the pars triangularis and orbitalis on identifying the frontal language area in patients with dominant frontal gliomas.

We have previously revealed that identification of the frontal language area (FLA) can be difficult in patients with dominant frontal glioma involving the pars triangularis (PT). The present study added new cases and performed additional analyses. We noticed a new finding that the presence of extension to the pars orbitalis (POr) was associated with negative response to the FLA. The aim of the present study was to evaluate the impact of PT involvement with extension to the POr on the failure to identify the FLA. From 2000 to 2017, awake craniotomy was performed on 470 patients. Of these patients, the present study included 148 consecutive patients with frontal glioma on the dominant side. We evaluated whether tumors involved the PT or extended to the POr. Thirty one of 148 patients showed involvement of the PT, and we examined the detailed characteristics of these 31 patients. The rate of negative response for the FLA was 61% in patients with involvement of the PT. In 31 patients with frontal glioma involving the PT, univariate analyses showed significant correlation between extension to the POr and failure to identify the FLA (P = 0.0070). Similarly, multivariate analysis showed only extension to the POr correlated significantly with failure to identify the FLA (P = 0.0129). We found new evidence that extension to the POr which impacts connectivity between the PT and POr correlated significantly with negative response to the FLA of patients with dominant frontal glioma.

Awake Craniotomy and Excision of a Diffuse Low-Grade Glioma in a Multilingual Patient: Neuropsychology and Language.

BACKGROUND: Diffuse low-grade gliomas are a group of brain tumors that require an individualized and targeted therapeutic approach, such as awake craniotomy for surgical resection and intraoperative monitoring of speech and language functions. CASE DESCRIPTION: This case report presents a young, right-handed, Tamil-English-Malay multilingual man who underwent awake brain surgery for the excision of a diffuse low-grade glioma in the left frontal pars triangularis and opercularis region (i.e., Broca's area). Preoperative and postoperative neuropsychological assessments were conducted. Intraoperative language mapping was performed with electrostimulation. CONCLUSION: Awake craniotomy with speech and language monitoring allows a customized approach to the treatment and management of diffuse low-grade gliomas. Neuropsychological assessment and intraoperative findings are discussed in the context of functional reorganization and cortical representations of language.

Modern operative nuances for the management of eloquent high-grade gliomas.

INTRODUCTION: Despite advancements in the treatment of high-grade gliomas (HGG), the rate of tumor recurrence is high and survival rate for the patient is low. Gross total resection has shown increased survival but the location of the tumor in the eloquent brain poses significant risk of morbidity. In this report, we focus on modern surgical nuances for resection of tumors located in the eloquent brain. EVIDENCE ACQUISITION: Research of the literature was conducted using the following search terms: surgical resection of gliomas, high-grade gliomas, and the role of vascular encasement - from 1986-2018. An institutional experience from the first author of this paper was also reviewed for selection of our illustrative cases. EVIDENCE SYNTHESIS: Gross total resection remains the mainstay of therapy for high-grade gliomas. The resection of the peritumoral FLAIR, when possible, has been associated with increased survival but also has the potential to cause increased morbidity. In the eloquent brain, the resection of the tumor itself is possible if attention is given to the interface of the tumor and brain, or if a safe pseudo-interface is created by the surgeon. Tumor-seeding to the ventricular system needs to be avoided. Devascularization, dissection away from the brain, and retractorless brain surgery are key to successful surgical outcomes. Management of the venous and arterial invasion/encasement are also outlined in this report. Technical aspects are discussed with corresponding videos. CONCLUSIONS: High-grade gliomas involving eloquent brain areas require a tailored treatment plan. While the medical treatment is undergoing quick evolution, gross total resection still remains one of the key milestones of treatment for improved survival. Surgical techniques play key role. We propose that encasement and/or the invasion of arteries and veins, should be considered equally as important as the eloquent brain when contemplating the resection of gliomas.

Awake craniotomy for a cavernous angioma in the Broca's area.

Cavernous angiomas constitute 5%-10% of cerebrovascular malformations and may cause seizure and neurological deficits from bleeding. 4 The authors present a case of a 44-year-old man with a 3.5-year history of epilepsy without complete seizure control despite anticonvulsants. Brain MRI showed a 2.8 cm cavernous angioma at the left pars opercularis, also known as the Broca's area. 3 The patient underwent an awake craniotomy for intraoperative cortical-subcortical language and sensory-motor mapping for a complete resection of the cavernous angioma and the hemosiderin rim. 1-6 The procedure was uneventful, and the patient evolved seizure free and with no deficits. The video can be found here: https://youtu.be/QajbLIsr_vg .

Individual Variability of the Human Cerebral Cortex Identified Using Intraoperative Mapping.

BACKGROUND: Intraoperative functional cortical mapping using direct electrical stimulation may show a wider individual variability than suggested by noninvasive imaging data of healthy subjects. METHODS: We assessed intraoperative variability of the frontal eye fields and the speech arrest sites in adult patients who underwent awake craniotomy with direct electrostimulation for treatment of diffuse gliomas located within eloquent regions, and we compared findings with human cortical parcellation of the Human Connectome Project. RESULTS: The frontal eye fields were defined by intraoperative direct electrostimulations (14.3% of patients) projected on the superior subdivision of the premotor cortex covering the areas defined as frontal eye fields (parcel index 10), area 55b (parcel index 12), and premotor eye field (parcel index 11) and in the posterior part of the dorsolateral prefrontal cortex covering the areas defined as inferior 6-8 transitional area (parcel index 97), area 8Av (parcel index 67), and area 8C (parcel index 73). The speech arrest sites were defined by intraoperative direct electrostimulations (100% of patients) projected predominantly posteriorly to the inferior frontal gyrus in the inferior subdivision of the premotor cortex, that is, rostral area 6 (parcel index 78), ventral area 6 (parcel index 54), and area 43 (parcel index 99). CONCLUSIONS: Intraoperative functional cortical mapping using direct electrostimulation highlights that actual individual variability is wider than suggested by analyses of healthy subjects and results in atypical patterns of functional organization and structural and functional changes of the human cerebral cortex under pathologic conditions.

A Systematic Review and Meta-Analysis of Studies Examining the Use of Brain Laser Interstitial Thermal Therapy versus Craniotomy for the Treatment of High-Grade Tumors in or near Areas of Eloquence: An Examination of the Extent of Resection and Major Complication Rates Associated with Each Type of Surgery.

BACKGROUND: The extent of resection (EOR) of high-grade gliomas (WHO grade III or IV) in or near areas of eloquence is associated with overall patient survival, but with higher major neurocognitive complications. METHODS: A systematic review and meta-analysis was undertaken of the peer-reviewed literature in order to identify studies which examined EOR or extent of ablation (EOA) and major complications (defined as neurocognitive or functional complications which last >3 months duration after surgery) associated with either brain laser interstitial thermal therapy (LITT) or open craniotomy in high-grade tumors in or near areas of eloquence. RESULTS: Eight studies on brain LITT (n = 79 patients) and 12 craniotomy studies (n = 1,036 patients) were identified which examined either/both EOR/EOA and complications. Meta-analysis demonstrated an EOA/EOR of 85.4 ± 10.6% with brain LITT versus 77.0 ± 40% with craniotomy (mean difference: 8%; 95% CI: 2-15; p = 0.01; inverse variance, random effects model). Meta-analysis of proportions of major complications for each individual therapy demonstrated major complications of 5.7% (95% CI: 1.8-11.6) and 13.8% (95% CI: 10.3-17.9) for LITT and craniotomy, respectively. CONCLUSION: In patients presenting with high-grade gliomas in or near areas of eloquence, early results demonstrate that brain LITT may be a viable surgical alternative.

High-resolution MEG source imaging approach to accurately localize Broca's area in patients with brain tumor or epilepsy.

OBJECTIVE: Localizing expressive language function has been challenging using the conventional magnetoencephalography (MEG) source modeling methods. The present MEG study presents a new accurate and precise approach in localizing the language areas using a high-resolution MEG source imaging method. METHODS: In 32 patients with brain tumors and/or epilepsies, an object-naming task was used to evoke MEG responses. Our Fast-VESTAL source imaging method was then applied to the MEG data in order to localize the brain areas evoked by the object-naming task. RESULTS: The Fast-VESTAL results showed that Broca's area was accurately localized to the pars opercularis (BA 44) and/or the pars triangularis (BA 45) in all patients. Fast-VESTAL also accurately localized Wernicke's area to the posterior aspect of the superior temporal gyri in BA 22, as well as several additional brain areas. Furthermore, we found that the latency of the main peak of the response in Wernicke's area was significantly earlier than that of Broca's area. CONCLUSION: In all patients, Fast-VESTAL analysis established accurate and precise localizations of Broca's area, as well as other language areas. The responses in Wernicke's area were also shown to significantly precede those of Broca's area. SIGNIFICANCE: The present study demonstrates that using Fast-VESTAL, MEG can serve as an accurate and reliable functional imaging tool for presurgical mapping of language functions in patients with brain tumors and/or epilepsies.

Pediatric Awake Craniotomy for Brain Lesions.

Awake craniotomy is a special method to prevent motor deficits during the resection of lesions that are located in, or close to, functional areas. Although it is more commonly performed in adult patients, reports of pediatric cases undergoing awake craniotomy are limited in the literature. In our clinic, where we frequently use awake craniotomy in adult patients, we performed this method in 2 selected pediatric cases for lesion surgery. At an early age, these 2 cases diagnosed with epilepsy presented cerebral lesions, but since the lesions enclosed functional areas, surgical resection was not regarded as a treatment option at this time. In these 2 pediatric cases, we successfully completed lesion surgery with awake craniotomy. The method and the techniques employed during surgery are presented concomitant with other reports in the literature.

[RADIOSURGERY OF INTRACEREBRAL CAVERNOMAS--CURRENT INTERNATIONAL TRENDS]. / AZ INTRACEREBRALIS CAVERNOMÁK SUGÁRSEBÉSZETE--HOL TART MA A VILÁG?

Although still a controversial management option, radio-surgery of intracranial cavernomas has become increasingly popular world-wide during the last decade. Microsurgery is a safe and effective treatment for symptomatic hemispheric cavernomas. However, the indication for microsurgical resection of deep eloquent cavernomas is relatively limited even in experienced hands. The importance of radiosurgery has recently been appreciated in parallel with increasing positive experiences both in terms of effectiveness and safety, especially for cases high risk for surgical resection, in the brainstem, thalamus and basal ganglia. While radiosurgery was earlier indicated mainly for surgically inaccessible lesions that had bled multiple times, a more proactive policy has recently become more accepted. In our opinion preventive treatment with the low morbidity radiosurgery serves the patients' interest especially for deep eloquent lesions that had bled not more than once, due to the cumulative morbidity of repeated hemorrhages. Despite our increasing knowledge on natural history, there is currently no available treatment algorithm for cavernomas. Arguments for all three treatment modalities (observation, microsurgery and radiosurgery) are established, but their indication criteria are yet to be defined. It is time to organize a prospective population based data collection in Hungary, which appears to be the most realistic way to clarify indication criteria.

[RADIOSURGERY OF INTRACEREBRAL CAVERNOMAS--CURRENT HUNGARIAN PRACTICE]. / AZ INTRACEREBRALIS CAVERNOMÁK SUGÁRSEBESZETE--HOL TART MAGYARORSZÁG?

BACKGROUND AND PURPOSE: Radiosurgery is an increasingly popular treatment option especially for deep eloquent intracerebral cavernomas that are often too risky for surgical removal, but their re-bleed carries significant risk for persisting neurological deficit. Gamma-radiation based radiosurgery has been being available since 2007 in Hungary in Debrecen. Our aim is to summarize our experience accumulated during the first five years of treatment and to compare it to the international experience. PATIENT SELECTION AND METHODS: We retrospectively analyzed 51 cavernomas in 45 patients treated between 2008 and 2012 in terms of localization, natural history, and the effect of radiosurgery on re-bleed risk and epilepsy, and its side effects. RESULTS: We treated 26.5% deep eloquent (brainstem, thalamic/basal ganglia) and 72.5% superficial hemispheric cavernomas. The median presentation age was 25 years (13-60) for deep, and 45 years (6-67) for superficial cavernomas. They were treated median of 1 year after presentation. 64.5% of deep cavernomas bled before treatment, the annual risk of first hemorrhage was 2%/lesion, re-bleed risk 21.7%, with 44% persisting morbidity. 13.5% of superficial cavernomas bled prior to treatment, the risk of first bleed was 0.3%, there was no re-bleed, and 35% caused epilepsy. We used GammaART-6000TM rotating gamma system for treatment, marginal dose was 14 Gy (10-16), and treatment volume 1.38-1.53 cm3. Re-bleed risk of deep eloquent lesions fell to 4% during the first two years after treatment and to 0% thereafter, and no hemorrhage occurred from superficial lesions after treatment. Persisting morbidity in deep lesions came from adverse radiation effect in 7% and from re-bleed in 7%, and there was no persisting side effect in superficial cavernomas. 87.5% of cases of epilepsy resistant to medical therapy improved. Radiological regression was found in 37.5% and progression in 2% after treatment. CONCLUSIONS: Radiosurgery of cavernomas is safe and effective. Early preventive treatment for deep cavernomas carrying high surgical risk is justified. Moreover, for superficial lesions that are surgically easily accessible radiosurgery also appears to be an attractive alternative.

Specificities of Awake Craniotomy and Brain Mapping in Children for Resection of Supratentorial Tumors in the Language Area.

BACKGROUND: In the pediatric population, awake craniotomy began to be used for the resection of brain tumor located close to eloquent areas. Some specificities must be taken into account to adapt this method to children. OBJECTIVE: The aim of this clinical study is to not only confirm the feasibility of awake craniotomy and language brain mapping in the pediatric population but also identify the specificities and necessary adaptations of the procedure. METHODS: Six children aged 11 to 16 were operated on while awake under local anesthesia with language brain mapping for supratentorial brain lesions (tumor and cavernoma). The preoperative planning comprised functional magnetic resonance imaging (MRI) and neuropsychologic and psychologic assessment. The specific preoperative preparation is clearly explained including hypnosis conditioning and psychiatric evaluation. The success of the procedure was based on the ability to perform the language brain mapping and the tumor removal without putting the patient to sleep. We investigated the pediatric specificities, psychological experience, and neuropsychologic follow-up. RESULTS: The children experienced little anxiety, probably in large part due to the use of hypnosis. We succeeded in doing the cortical-subcortical mapping and removing the tumor without putting the patient to sleep in all cases. The psychological experience was good, and the neuropsychologic follow-up showed a favorable evolution. CONCLUSIONS: Preoperative preparation and hypnosis in children seemed important for performing awake craniotomy and contributing language brain mapping with the best possible psychological experience. The pediatrics specificities are discussed.

[Intraoperativ electrophysiological monitoring during neurosurgery on eloquent structures]. / Intraoperatív elektrofiziológia elokvens idegrendszeri struktúrákat erinto idegsebészeti beavatkozások során.

OBJECTIVE: We summarize our experiences on intraoperative electrophysiological monitoring during neurosurgical procedures on eloquent neuronal structures. PATIENTS, METHODS: Sixty patients were enrolled retrospectively in our study with pathologies involving eloquent neuronal structures. They were operated between May 2011. and March 2012. at the University of Debrecen, Department of Neurosurgery and at the National Institute of Neurosciences. Patients underwent standard preoperative examinations due to the primary pathology. In all cases we used intraoperative electrophysiological monitoring. We had 22 cases with cranial nerve monitoring, 10 cases with cauda monitoring, 16 cases with motor system monitoring, six cases with complex spinal cord monitoring, three degenerative spine reconstructions and 3 awake surgeries. RESULTS: We found that with the use of intraoperative electrophysiology we could make these neurosurgical procedures safer, and were able to optimize the extent of resection in the cases of oncological pathologies. CONCLUSIONS: Our experiences as well as the international literature suggests that in certain high risk neurosurgical procedures intraoperative electrophysiology is indispensible for safe and optimally extended operation.

Intraoperative subcortical mapping of a language-associated deep frontal tract connecting the superior frontal gyrus to Broca's area in the dominant hemisphere of patients with glioma.

OBJECT: The deep frontal pathway connecting the superior frontal gyrus to Broca's area, recently named the frontal aslant tract (FAT), is assumed to be associated with language functions, especially speech initiation and spontaneity. Injury to the deep frontal lobe is known to cause aphasia that mimics the aphasia caused by damage to the supplementary motor area. Although fiber dissection and tractography have revealed the existence of the tract, little is known about its function. The aim of this study was to determine the function of the FAT via electrical stimulation in patients with glioma who underwent awake surgery. METHODS: The authors analyzed the data from subcortical mapping with electrical stimulation in 5 consecutive cases (3 males and 2 females, age range 40-54 years) with gliomas in the left frontal lobe. Diffusion tensor imaging (DTI) and tractography of the FAT were performed in all cases. A navigation system and intraoperative MRI were used in all cases. During the awake phase of the surgery, cortical mapping was performed to find the precentral gyrus and Broca's area, followed by tumor resection. After the cortical layer was removed, subcortical mapping was performed to assess language-associated fibers in the white matter. RESULTS: In all 5 cases, positive responses were obtained at the stimulation sites in the subcortical area adjacent to the FAT, which was visualized by the navigation system. Speech arrest was observed in 4 cases, and remarkably slow speech and conversation was observed in 1 case. The location of these sites was also determined on intraoperative MR images and estimated on preoperative MR images with DTI tractography, confirming the spatial relationships among the stimulation sites and white matter tracts. Tumor removal was successfully performed without damage to this tract, and language function did not deteriorate in any of the cases postoperatively. CONCLUSIONS: The authors identified the left FAT and confirmed that it was associated with language functions. This tract should be recognized by clinicians to preserve language function during brain tumor surgery, especially for tumors located in the deep frontal lobe on the language-dominant side.

Correlation between surgical manipulations and the variation of surgeon's heart rate in brain surgery: technical note.

For improvement of surgical performance and safety, we record surgeries by video cameras. However, analysis of the video records is time consuming. To help this task, we are developing methods to automatically mark up significant time points in the surgery. As a possible mean for the marking, we focused on the surgeon's heart rate. During a craniotomy of an intracranial glioma, we recorded the surgeon's electrocardiogram using a telemeter and measured the R-to-R interval (RRI). We detected the stable state of heart rate as a peak-to-peak RRI of less than 5% of the mean of RRI data from 15 consecutive heartbeats. We also quantified the frequency of brain touches by the surgeon under the surgical microscope. We examined the association between the stability of surgeon's heart rate and the brain touches using a chi-square test. As the result, the stable state of surgeon's heart rate was associated with the brain touches (p < 0.05, odds ratio 5.1). We edited a one-minute digest video of the surgery based on only the heart rate data, and it was sufficient to understand how the surgery was preceded.