Burr Hole Research Articles

Emergency department burr hole simulation using 3D-printed model

BackgroundTraumatic epidural hematoma (EDH) with the potential to displace the brain tissue and increase intracranial pressure (ICP), is a life-threatening condition that requires emergent intervention. In rare circumstances, Emergency Physician (EP) may have to do skull trephination to reduce the ICP as a temporary measure. Specific aimsTo evaluate emergency medicine (EM) residents' comfort in performing emergency department (ED) burr holes and to assess their difficulties and evaluate comfort level before and after simulated EDH cases. Materials and methodsA 3D-printed skull, electrical and manual drills were used for the simulation. Subjective comfort level pre and post-procedure, as well as objective procedural skills and time to complete the drill, were recorded. ResultsTwenty EM residents participated in the simulation study. The median time to perforate through the skull was 4 s for the electric drill and 10 s for the manual drill. A comfort level of 5 and above was reported by 12 participants for the manual drill and by 17 participants for the electric drill. Six participants had mild and 2 participants had moderate observed difficulty in handling the manual and electric drill. Most participants performed both procedures successfully with one attempt only. Three participants have an overall comfort level above 5 before the simulation and 13 participants had overall comfort level above 5 post-simulation. ConclusionThe 3D-printed model assisted the ED burr hole simulation and the residents could perform the procedure with minimum difficulties.

Predictors of revision surgery after bedside subdural drain placement for chronic subdural hematomas

Background and objectiveFor chronic subdural hematoma (cSDH), bedside subdural drains (SDD) provide a useful alternative to more invasive neurosurgical techniques, including evacuation through multiple burr holes or formal craniotomy. However, no scale currently exists adequately predicting SDD candidacy or treatment response. The present study sought to characterize predictors of revision surgery after initial treatment with bedside SDD for cSDH. MethodsWe conducted a retrospective case control study of cSDH patients treated with bedside SDD at a level one trauma center between 2018 and 2022. Binomial regression was used to compare SDD patients and generate odds ratios associated with revision surgery, which were compared using a binary random effects model. ResultsNinety six cSDH patients were included, of whom 13 (13.5%) required a revision surgery after initial treatment failure with bedside SDD. Patients requiring revision surgery demonstrated an increased male predominance (84.6% vs. 69.9% of SDD patients not requiring revision surgery), tended to be younger (67.8 vs. 70.5 years) with a greater body mass index (28.7 vs. 25.6 kg/m2), and have a lower Glasgow Coma Scale (GCS) score on presentation of 12.5 (versus 14). Patients with an initial GCS score less than 13 (OR 11.0 95% CI 2.8 – 43.3), midline shift greater than 10 mm on CT (OR 6.5 95% CI 1.7 – 25.7), or duration of SDD placement longer than 3 days (OR 10.5 95% CI 2.6 – 41.9) demonstrated a greater likelihood of needing a revision surgery after initial treatment with bedside SDD. ConclusionAmong patients treated with SDD, we identified 3 independent factors predicting the need for revision surgery: GCS score, midline shift, and duration of drain placement. Craniotomy may be favored over bedside SDD in patients presenting with a GCS score less than 13 or midline shift greater than 10 mm and for SDD patients demonstrating inadequate clinical response after 3 days.

ASL-MRI-guided evaluation of multiple burr hole revascularization surgery in Moyamoya disease

PurposeMoyamoya (MM) disease is characterized by progressive intracranial arterial stenosis. Patients commonly need revascularization surgery to optimize cerebral blood flow (CBF). Estimation of CBF and cerebrovascular reserve (CVR) is therefore necessary before and after surgery. However, assessment of CBF before and after indirect revascularization surgery with the multiple burr hole (MBH) technique in MM has not been studied extensively. In this study, we describe our initial experience using arterial spin labeling magnetic resonance perfusion imaging (ASL-MRI) for CBF and CVR assessment before and after indirect MBH revascularization surgery in MM patients.MethodsEleven MM patients (initial age 6–50 years, 1 male/10 female) with 19 affected hemispheres were included. A total of 35 ASL-MRI examinations were performed using a 3D-pCASL acquisition before and after i.v. acetazolamide challenge (1000 mg in adults and 10 mg/kg in children). Twelve MBH procedures were performed in seven patients. The first follow-up ASL-MRI was performed 7–21 (mean 12) months after surgery.ResultsBefore surgery, CBF was 46 ± 16 (mean ± SD) ml/100 g/min and CVR after acetazolamide challenge was 38.5 ± 9.9 (mean ± SD)% in the most affected territory (middle cerebral artery). In cases in which surgery was not performed, CVR was 56 ± 12 (mean ± SD)% in affected hemispheres. After MBH surgery, there was a relative change in CVR compared to baseline (preop) of + 23.5 ± 23.3% (mean ± SD). There were no new ischemic events.ConclusionUsing ASL-MRI we followed changes in CBF and CVR in patients with MM. The technique was encouraging for assessments before and after revascularization surgery.

Inflammatory biomarkers differentiate the stage of maturation in chronic subdural hematomas

ObjectiveInflammation is a major pathophysiological driver of the development of chronic subdural hematomas (CSDH), but there is still limited knowledge on the key molecular processes and corresponding biomarkers involved in this disease. In this study, the aim was to study a subset of inflammatory biomarkers and their relation to the clinical status of the patient and the radiological characteristics of the CSDH. MethodsIn this observational study, 58 patients who were operated on with CSDH evacuation, at the Department of Neurosurgery, Uppsala, Sweden, between 2019 and 2021, were prospectively included. The CSDH fluid was collected peri-operatively and was later analyzed with proximity extension assay (PEA) technique (Olink) for a panel of 92 inflammatory biomarkers. Demographic, neurological (Markwalder), radiological (general (Nakaguchi classification) and focal (septa below the burr holes)), and outcome variables were collected. ResultsIn 84 of the 92 inflammatory biomarkers, the concentration was above the detection limit in >50% of the patients. There was a significant difference in GDNF, NT-3, and IL-8 depending on the Nakaguchi class, with higher values in the trabeculated CSDH subtype. In addition, those with septa at the focal area of CSDH collection, had higher levels of GDNF, MCP-3, NT-3, CXCL1, CXCL5, IL8, and OSM. There was no association between Markwalder grade and the inflammatory biomarkers. ConclusionsOur findings support the presence of local inflammation in the CSDH, a shift in biomarker pattern as the CSDH matures towards the trabeculated state, potentially differences in biomarker patterns within the CSDH depending on the focal environment with presence of septa, and that the brain might develop protective mechanisms (GDNF and NT-3) in case of mature and long-standing CSDHs.

Evaluation of 3D Printed Burr Hole Simulation Models Using 8 Different Materials

3D printing is increasingly used to fabricate three-dimensional neurosurgical simulation models, making training more accessible and economical. 3D printing includes various technologies with different capabilities for reproducing human anatomy. This study evaluated different materials across a broad range of 3D printing technologies to identify the combination that most precisely represents the parietal region of the skull for burr hole simulation. Eight different materials (polyethylene terephthalate glycol, Tough PLA, FibreTuff, White Resin, BoneSTN, SkullSTN, polymide [PA12], glass-filled polyamide [PA12-GF]) across 4 different 3D printing processes (fused filament fabrication, stereolithography, material jetting, selective laser sintering) were produced as skull samples that fit into a larger head model derived from computed tomography imaging. Five neurosurgeons conducted burr holes on each sample while blinded to the details of manufacturing method and cost. Qualities of mechanical drilling, visual appearance, skull exterior, and skull interior (i.e., diploë) and overall opinion were documented, and a final ranking activity was performed along with a semistructured interview. The study found that 3D printed polyethylene terephthalate glycol (using fused filament fabrication) and White Resin (using stereolithography) were the best models to replicate the skull, surpassing advanced multimaterial samples from a Stratasys J750 Digital Anatomy Printer. The interior (e.g., infill) and exterior structures strongly influenced the overall ranking of samples. All neurosurgeons agreed that practical simulation with 3D printed models can play a vital role in neurosurgical training. The study findings reveal that widely accessible desktop 3D printers and materials can play a valuable role in neurosurgical training.

MER and increased operative time are not risk factors for the formation of pneumocephalus during DBS

Although only recently directional leads have proven their potential to compensate for sub-optimally placed electrodes, optimal lead positioning remains the most critical factor in determining Deep Brain Stimulation (DBS) outcome. Pneumocephalus is a recognized source of error, but the factors that contribute to its formation are still a matter of debate. Among these, operative time is one of the most controversial. Because cases of DBS performed with Microelectrode Recordings (MER) are affected by an increase in surgical length, it is useful to analyze whether MER places patients at risk for increased intracranial air entry. Data of 94 patients from two different institutes who underwent DBS for different neurologic and psychiatric conditions were analyzed for the presence of postoperative pneumocephalus. Operative time and use of MER, as well as other potential risk factors for pneumocephalus (age, awake vs. asleep surgery, number of MER passages, burr hole size, target and unilateral vs. bilateral implants) were examined. Mann-Whitney U and Kruskal-Wallis tests were utilized to compare intracranial air distributions across groups of categorical variables. Partial correlations were used to assess the association between time and volume. A generalized linear model was created to predict the effects of time and MER on the volume of intracranial air, controlling for other potential risk factors identified: age, number of MER passages, awake vs. asleep surgery, burr hole size, target, unilateral vs. bilateral surgery. Significantly different distributions of air volume were noted between different targets, unilateral vs. bilateral implants, and number of MER trajectories. Patients undergoing DBS with MER did not present a significant increase in pneumocephalus compared to patients operated without (p = 0.067). No significant correlation was found between pneumocephalus and time. Using multivariate analysis, unilateral implants exhibited lower volumes of pneumocephalus (p = 0.002). Two specific targets exhibited significantly different volumes of pneumocephalus: the bed nucleus of the stria terminalis with lower volumes (p < 0.001) and the posterior hypothalamus with higher volumes (p = 0.011). MER, time, and other parameters analyzed failed to reach statistical significance. Operative time and use of intraoperative MER are not significant predictors of pneumocephalus during DBS. Air entry is greater for bilateral surgeries and may be also influenced by the specific stimulated target.

Administration of Tranexamic Acid After Burr Hole Craniotomy Reduced Postoperative Recurrence of Chronic Subdural Hematoma in a Japanese Regional Population.

Although tranexamic acid (TXA) has occasionally been used to prevent postoperative recurrence of chronic subdural hematoma (CSDH) after burr hole craniotomy (BC), robust evidence of its efficacy has been lacking. To assess the efficacy and safety of postoperative oral administration of TXA after BC for CSDH among the elderly. This retrospective, propensity score-matched cohort study was carried out with a large Japanese local population-based longitudinal cohort in the Shizuoka Kokuho Database between April 2012 and September 2020. Patients included were age 60 years or older and had undergone BC for CSDH but were not undergoing dialysis. Covariates were collected from records of the preceding 12 months from the month of first BC, and patients were followed up for 6 months after surgery. The primary outcome was repeat surgery, and the secondary outcome was death or the onset of thrombosis. Data on postoperative TXA administration were collected and compared with controls using propensity score matching. Of the 8544 patients who underwent BC for CSDH, 6647 were included, with 473 placed in the TXA group and 6174 placed in the control group. After 1:1 matching, repeated BC was found to have been performed in 30 of 465 patients (6.5%) in the TXA group and in 78 of 465 patients (16.8%) in the control group (relative risk, 0.38; 95% CI, 0.26-0.56). No significant difference was observed for death or the onset of thrombosis. Oral administration of TXA reduced the occurrence of repeat surgery after BC for CSDH.

Factors influencing the reliability of intraoperative testing in deep brain stimulation for Parkinson’s disease

BackgroundSeveral meta-analyses comparing the outcome of awake versus asleep deep brain stimulation procedures could not reveal significant differences concerning the postoperative improvement of motor symptoms. Only rarely information on the procedural details is provided for awake operations and how often somnolence and disorientation occurred, which might hamper the reliability of intraoperative clinical testing. The aim of our study was to investigate possible influencing factors on the occurrence of somnolence and disorientation in awake DBS procedures.MethodsWe retrospectively analyzed 122 patients with Parkinson's disease having received implantation of a DBS system at our centre. Correlation analyses were performed for the duration of disease prior to surgery, number of microelectrode trajectories, AC-PC-coordinates of the planned target, UPDRS-scores, intraoperative application of sedative drugs, duration of the surgical procedure, perioperative application of apomorphine, and the preoperative L-DOPA equivalence dosage with the occurrence of intraoperative somnolence and disorientation.ResultsPatients with intraoperative somnolence were significantly older (p=0.039). Increased duration of the DBS procedure (p=0.020), delayed start of the surgery (p=0.049), higher number of MER trajectories (p=0.041), and the patients’ % UPDRS improvement (p=0.046) also correlated with the incidence of intraoperative somnolence. We identified the main contributing factor to intraoperative somnolence as the use of sedative drugs applied during skin incision and burr hole trepanation (p=0.019). Perioperatively applied apomorphine could reduce the occurrence of somnolent phases during the operation (p=0.026).ConclusionSeveral influencing factors were found to seemingly increase the risk of intraoperative somnolence and disorientation, while the use of sedative drugs seems to be the main contributing factor. We argue that awake DBS procedures should omit the use of sedatives for best clinical outcome. When reporting on awake DBS surgery these factors should be considered and adjusted for, to permit reliable interpretation and comparison of DBS study results.

ID: 214384 Postoperative DBS Pneumocephalus Volume in Patients With Parkinson's Disease: Correlating Burr-Hole Size and Intraoperative Duration

Pneumocephalus can be linked to brain shift and impact the accuracy of stereotactic Deep Brain Stimulation (DBS) surgery. Previous literature has been unable to establish a correlation between burr hole size and the amount of pneumocephalus seen. Consequently, this work sought to determine if intraoperative burr hole size positively correlated with the volume of pneumocephalus observed on postoperative CT imaging in patients who underwent DBS. The duration of the surgery was also considered in order to see its impact on the pneumocephalus volume.

P.122 Chronic subdural hematoma drainage under local vs. general anesthesia: systematic review and meta-analysis

Background: Chronic subdural hematoma (CSDH) is one of the most encountered conditions seen in neurosurgery. Although mainstay treatment of cSDH has been burr hole drainage, no consensus yet exists on optimal anesthesic technique for surgical treatment between general (GA) and local (LA) anesthesia. Methods: A search was conducted in MEDLINE (1946 to November 11, 2022), Embase (1974 to November 11, 2022), and PubMed (up to November 11, 2022). We followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines to systematically screen studies. Results: Our literature search identified 521 studies, out of which 20 were included. There were a total of 1750 patients who underwent CSDH drainage under LA. The weighted mean age was 71.0 years, and 27.1% were female. Postoperative complication rate was significantly lower in the LA group (odds ratio 0.44, p = 0.004). The mean operative time (mean difference -29.28 minutes, p &lt;0.0001) and length of admission (mean difference -1.58 days, p = 0.0002) were significantly shorter in the LA group. Conclusions: In this meta-analysis, LA shows benefits in shorter operative time, shorter admission length, and fewer postoperative complications. This makes local anesthesia a less invasive alternative to general anesthesia especially in elderly patients.

Deployment of an electrocorticography system with a soft robotic actuator.

Electrocorticography (ECoG) is a minimally invasive approach frequently used clinically to map epileptogenic regions of the brain and facilitate lesion resection surgery and increasingly explored in brain-machine interface applications. Current devices display limitations that require trade-offs among cortical surface coverage, spatial electrode resolution, aesthetic, and risk consequences and often limit the use of the mapping technology to the operating room. In this work, we report on a scalable technique for the fabrication of large-area soft robotic electrode arrays and their deployment on the cortex through a square-centimeter burr hole using a pressure-driven actuation mechanism called eversion. The deployable system consists of up to six prefolded soft legs, and it is placed subdurally on the cortex using an aqueous pressurized solution and secured to the pedestal on the rim of the small craniotomy. Each leg contains soft, microfabricated electrodes and strain sensors for real-time deployment monitoring. In a proof-of-concept acute surgery, a soft robotic electrode array was successfully deployed on the cortex of a minipig to record sensory cortical activity. This soft robotic neurotechnology opens promising avenues for minimally invasive cortical surgery and applications related to neurological disorders such as motor and sensory deficits.

Клинический случай применения малоинвазивного «burr hole» микрохирургического доступа в хирургии опухолей боковых желудочков

The case of the large lateral ventricle tumor total removal using the minimally invasive bilateral burr hole microsurgical approach is reported.

Safety and Performance of a New Burr Hole Covering Device: Results of the Multicenter COVER Registry.

Burr hole covering in brain surgical procedures can avoid complications and unaesthetic results. The aim of this registry was to assess the safety and performance of a new polymeric burr hole covering device (Cranial COVER, NEOS Surgery). A multicenter, prospective, clinical registry design was used for the study. All the patients who fulfilled the inclusion criteria were included in the study and followed up for 6 months. Baseline clinical parameters, surgical variables (technical success of the implantation, surgeon satisfaction), postoperative variables (aesthetic and functional results, neuroimaging artifacts), and adverse events were evaluated. Forty-three Cranial COVER devices were implanted in 30 patients. Most of them were implanted in frontal locations (53.5%). After implantation, 97.7% of the devices completely covered the burr hole, and 100% perfectly adapted to the skull surface. All surgeons ranked their satisfaction with the implantation procedure as very high or high. No artifacts were detected in any of the neuroimaging studies performed and no adverse events related with the device or its implantation were reported during the follow-up. There were significantly more scalp depressions associated with uncovered than with Cranial COVER-covered burr holes (p = 0.040). Patient satisfaction with covered burr holes located in the frontal and parietal areas was 9.0 ± 1.4 over 10. Cranial COVER is a safe and reliable burr hole covering system that offers excellent cosmetic results and high satisfaction rates for both surgeons and patients. Cranial COVER is highly adaptable to the skull surface, and it was predominantly used in frontal locations due to their cosmetic importance.

Practical Training for Emergency Burr Hole Using Three-Dimensional Printed Task Trainer

Practical Training for Emergency Burr Hole Using Three-Dimensional Printed Task Trainer

Complications From Subdural Drains in Burr Hole Drainage of Chronic and Subacute Subdural Haematomas: A Single-Centre Experience.

Introduction The use of drains following the burr-hole evacuation of chronic (CSDH) and subacute subdural haematomas (SASDH) is a well-established practice offering a significant reduction in recurrence rates and improvement of survival. The purpose of this work is to investigate the complication rate of subdural drains following the burr-hole evacuation of CSDH and SASDH. Methods A retrospective review of the clinical records of all patients managed surgically for CSDH or SASDH was conducted. Patients over 18 years, that met the criteria for surgical evacuation, were included in this study. Patients admitted for CSDH or SASDH but managed either conservatively or with craniotomy were excluded from further analysis. Results A total of 97 cases, with a mean age at the time of diagnosis of 78.25 years were identified in which 122 drains were used. Three complications, two acute subdural haematomas, and one case of drain-associated seizures were identified, yielding an overall complication rate of 3%. Conclusion The use of intradural drains is associated with a small, yet not negligible, possibility of serious complications.

The efficacy of postoperative middle meningeal artery embolization on chronic subdural hematoma - A multicentered randomized controlled trial.

Middle meningeal artery (MMA) embolization has recently emerged as a potential treatment for chronic subdural hematoma (cSDH). Numerous retrospective studies have suggested that it can potentially reduce the risk of hematoma recurrence following surgical evacuation. We have conducted a randomized controlled trial to investigate the effectiveness of postoperative MMA embolization in reducing recurrence rate, residual hematoma thickness as well as improving functional outcome. Patients aged 18 or above were recruited. Following evacuation through burr hole or craniotomy, patients were randomly allocated to undergo either MMA embolization or standard care (monitoring). The primary outcome was symptomatic recurrence requiring redo evacuation. Secondary outcomes include residual hematoma thickness and modified Rankin Scale (mRS) at 6 weeks and 3 months. Thirty-six patients (41 cSDHs) were recruited between April 2021 and September 2022. Seventeen patients (19 cSDHs) were allocated to the embolization group and 19 patients (22 cSDHs) were in the control group. No symptomatic recurrence was observed in the treatment group while 3 control patients (15.8%) underwent repeat surgery for symptomatic recurrence, however, it was not statistically significant (P = 0.234). Furthermore, there was no significant difference in residual hematoma thickness at 6 weeks or 3 months between the two groups. All patients in the embolization group had a good functional outcome (mRS 0-1) at 3 months, which was significantly higher than the 53% observed in the control group. No complications related to MMA embolization were reported. Further study with larger sample size is required to evaluate the efficacy of MMA embolization.

Practice of treating Chronic Subdural Hematoma (cSDH) among Neurosurgeons in Nepal: A nationwide survey with literature review

Objectives: To survey Nepali neurosurgeons regarding the practice of managing chronic subdural hematomas (cSDH). Methods and Materials: A survey questionnaire was sent to all neurosurgeons practicing in Nepal from the database of the Nepalese Society of Neurosurgeons (NESON). Results: 60% (50/84) responded to the questionnaire. There was variation in practice among neurosurgeons regarding the use of drain and the administration of antiepileptics. However, many concurred regarding postoperative computed tomography scan, size of the burr hole, and positioning after surgery. Conclusion: For a common neurosurgical procedure like drainage of cSDH, scientific evidence keeps on changing. Based on the available evidence we need to change our practice for the best possible outcomes. For most of the variables studied, there is concordance with available scientific evidence among neurosurgeons regarding cSDH management in Nepal.

Burr hole locations are associated with recurrence in single burr hole drainage surgery for chronic subdural hematoma

BackgroundVarious factors have been reported as risk factors for chronic subdural hematomas (CSDH) recurrence. However, few studies have quantitatively evaluated the impact of CSDH locations and burr hole positions on recurrence. This study aimed to reveal the relation between CSDH recurrence and the locations of CSDH and burr holes. MethodsInitial single burr hole surgeries for CSDH with a drainage tube between April 2005 and October 2021 at Otemae Hospital were enrolled. Patients’ medical records, CSDH volume, and CSDH computed tomography values (CTV) were evaluated. The locations of CSDH and burr holes were assessed using Montreal Neurological Institute coordinates. ResultsA total of 223 patients were enrolled, including 34 patients with bilateral CSDH, resulting in 257 surgeries investigated. The rate of CSDH recurrence requiring reoperation (RrR) was 13.5%. The RrR rate was significantly higher in patients aged ≥76 years, those with bilateral CSDH, and those with postoperative hemiplegia. In RrR, the preoperative CSDH volume was significantly larger, and CTV was significantly smaller. The locations of CSDH had no influence on recurrence. However, in RrR, the locations of burr holes were found to be more lateral and more ventral. Multivariate Cox proportional hazards regression analysis showed that bilateral CSDH, more ventral burr hole positions, and postoperative hemiplegia were risk factors for recurrence. ConclusionsThe locations of burr holes are associated with CSDH recurrence. In RrR, CSDH profiles tend to show a larger volume and reduced CTV. Hemiplegia after burr hole surgery serves as a warning sign for RrR.

Comparison of the Burr Hole Craniostomy Techniques for the Treatment of Chronic Subdural Hematoma

Objective: To compare three different surgical techniques for chronic subdural hematoma (CSDH), one of the most common neurosurgical diseases increasingly affecting the elderly, and for which there is no standard treatment currently. Material and Methods: We included 28 patients diagnosed with CSDH and retrospectively analysed their data. The surgical techniques were compared to subgroups of the burr-hole craniostomy technique. Results: The mean age of included patients was 72.71 ± 10.81 years, and the male/female ratio was 2/5. Preoperative subdural hematoma volume was 113.63 ± 40.74 cc, and the Hounsfield unit value was 33.66 ± 8.67 HU. The mean operative time was 60.89 ± 20.04 min, and the mean hospital stay was 6.17 ± 2.56 days. Detectable radiologic complete recovery was 42.69 ± 17.46 days. Conclusion: All surgery subgroups experienced successful outcomes during long-term follow-up. The irrigation technique demonstrated no superiority to the other two techniques and the complication rate was significantly lower with the endoscopic technique

Initial Clinical Experience with Thin-Film Polyimide Subdural Electrodes for Seizure Monitoring (P2-1.005)

<h3>Objective:</h3> NA <h3>Background:</h3> Subdural grid-and-strips are used routinely in pre-surgical evaluations for people with drug-resistant epilepsy (DRE). Thin-film polyimide electrodes (NeuroOne Evo, 0.08mm) which have been approved for clinical use, are thinner and better conform to brain convolutions than current market grids. <h3>Design/Methods:</h3> We present two patients with DRE who underwent intracranial EEG (iEEG) monitoring with thin-film polyimide subdural electrode grid- and-strip electrodes as well as traditional EEG for pre-surgical evaluation. Patient 1 had a prior left mesial temporal lobe ablation with seizure recurrence. They underwent left temporal craniotomy with implantation of two subdural grids, three strips and additional depth electrodes. IEEG demonstrated two habitual seizures arising from anterior temporal subdural strips. Functional mapping identified the basal-temporal and Wernicke’s speech areas. Left anterior temporal lobectomy was performed and he remains seizure free 9 months post-resection. Patient 2 underwent bilateral stereoEEG electrode placement with coverage in the frontal/temporal/insular regions and subdural strip electrodes. IEEG demonstrated seizure onset from the left hippocampus and right hippocampal spikes. Given bilateral findings, they underwent Responsive Neurostimulation System implantation. <h3>Results:</h3> The two patients underwent subdural electrode placements without complications. IEEG recordings were comparable between NeuroOne Evo and traditional electrodes in terms of integrity, artifactual content and signal recording characteristics. The thinner profile of the Evo grid tail facilitated dura closure and reduced mass effect compared to traditional grids. By trimming material from the tip of the subdural strip, the electrode was placed through a burr hole without difficulty. Recording from these grids contributed to presurgical evaluation and led to surgical interventions. <h3>Conclusions:</h3> Our initial experience suggests that thin-film electrodes are a viable option for subdural iEEG that could safely minimize intracranial mass effect/brain shift and improve surgical ease of use. <b>Disclosure:</b> Dr. Reina has nothing to disclose. Dr. Song has received personal compensation in the range of $0-$499 for serving as a Consultant for Clearpoint Neuro. The institution of Dr. Song has received research support from NIH. Dr. Culler has nothing to disclose. Dr. Aronson has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Medtronic.