MR-guided Laser Interstitial Thermal Therapy Research Articles

An Overview of MR-Guided Laser Interstitial Thermal Therapy (MRg-LITT) in Disrupting the Blood-Brain Barrier: Efficacy and Duration.

The blood-brain barrier (BBB) is a selectively semi-permeable layer, crucial in shielding the brain from external pathogens and toxic substances while maintaining ionic homeostasis and sufficient nutrient supply. However, it poses a significant challenge for drugs to penetrate the BBB in order to effectively target brain tumors. Magnetic resonance-guided laser interstitial thermal therapy (MRg-LITT) is a minimally invasive technique that employs thermal energy to cauterize intracranial lesions with the potential to temporarily disrupt the BBB. This further opens a possible therapeutic window to enhance patient outcomes. Here, we review the impact of MRg-LITT on BBB and blood tumor barrier (BTB) and the duration of the BBB disruption. Studies have shown that MRg-LITT is effective due to its minimally invasive nature, precise tumor targeting, and low complication rates. Although the disruption duration varies across studies, the average peak disruption is within the initial two weeks post-ablation period and subsequently exhibits a gradual decline. However, further research involving larger groups with extended follow-up periods is required to determine disruption duration more accurately. In addition, evaluating toxicity and glymphatic system disruption is crucial to circumvent potential risks associated with this procedure.

61 Increased Apathy Post-Laser Ablation for Refractory Obsessive-Compulsive Disorder

Objective:Severe OCD is often nonresponsive to pharmacological and behavioral therapies and thus surgical interventions are emerging. Surgical interventions have proven to be efficacious for treating refractory OCD, however limited publications suggest 22–40% of patients experience transient apathy and disinhibition post-surgery (McLaughlin et al., 2021). Apathy is highly associated with the same brain regions, the prefrontal cortex, striatum, and thalamus, which have also been implicated in OCD symptoms (Le Heron et al., 2018). Prior research noting post-surgical changes in apathy in OCD either used physician observations or less precise surgical methods (i.e., gamma knife or radiofrequency ablation). Apathy has also been highly associated with depression and executive dysfunction (Raffard et al, 2020) and often not co-assessed in prior studies. The newest intervention, cutting-edge MR-guided laser interstitial thermal therapy (LITT), limits damage outside the region of interest by precise control of thermal application in real-time. Thus, the current case series aims to investigate objective patient-reported change in apathy, disinhibition, depression, and executive dysfunction following anterior capsulotomy via this newest surgical approach for OCD.Participants and Methods:In this retrospective study, the responses of ten consecutive patients pre- and post-LITT on the following measures were examined: Frontal Systems Behavior Scale (FrSBe), Beck Depression Inventory-II (BDI-II), and Yale Brown Obsessive-Compulsive Scale (Y-BOCS). Reliable Change Index (RCI) was used to evaluate meaningful change in pre- and post-LITT self-reported levels of apathy, disinhibition, executive dysfunction, along with depressive symptoms. Per prior published guidelines, patient-reported Y-BOCS (range 0–40) scores were used to measure OCD symptoms with 24–34 % score reduction representing partial and 35% or greater score reduction representing full response (Pepper et al., 2019).Results:Seven patients (70%) were male, with a sample mean age of 38.4 (SD=13.6) and a mean of 14.6 (SD =2.27) years of education. Mean Y-BOCS score decreased from 32 (SD=5.3) before surgery to 18.8 (SD=11.1) after. Over 65% had partial or full response in OCD symptoms post-surgery. Six patients endorsed increased apathy, with others endorsing no change. Half of the non-responders reported this increase in apathy. The cohort remained relatively stable in disinhibition and executive dysfunction. Over half the cohort demonstrated a significant decrease in depressive symptoms. Interestingly, two of the non-responders and one responder endorsed increased apathy despite stable or improving depressive symptoms, disinhibition, and executive dysfunction.Conclusions:Surgical interventions for psychiatric disorders are emerging quickly and being refined daily. In this cohort, anterior capsulotomy via LITT provided full or partial OCD recovery for most patients. However, most patients reported significant increases in apathy, despite experiencing a decrease in depressive symptoms, with stable disinhibition and executive dysfunction. Despite these promising improvements in OCD symptomatology via LITT, impact of surgery on apathy levels is clearly warranted using objective, quantifiable methods. As apathy has consistently been related to functional impairment and poorer quality of life, understanding this outcome is imperative in larger trials. Better understanding of this finding and underlying circuity will allow patients to be fully informed regarding this promising surgical intervention.

Clinical outcomes of MR-guided laser interstitial thermal therapy corpus callosum ablation in drug-resistant epilepsy: a systematic review and meta-analysis.

The goal of this systematic review and meta-analysis was to provide an updated analysis of studies investigating outcomes, morbidity, and mortality associated with MR-guided laser interstitial thermal therapy (MRgLITT) corpus callosum ablation (CCA). Study inclusion criteria for screening required that studies report on human subjects only, including patients aged 1-52 years diagnosed with drug-resistant epilepsy who underwent CCA. Sixteen articles published between 2016 and 2023 were included for the systematic review and analysis, including 4 case reports, 11 case series, and 1 case-control study. Altogether, 85 pediatric and adult patients undergoing CCA were included in the systematic review (46 patients younger and 39 patients older than 21 years). The main outcome of seizure freedom was measured using the decrease in the frequency of atonic seizures following surgery, percentage of atonic seizure freedom following surgery, and percentage of overall seizure freedom following surgery. These measurements were made using data from the last follow-up for patients with at least 6 months of follow-up post-CCA. The extent of CCA differed across the pooled cohorts, including anterior two-thirds CCA (38.89%, n = 35) and posterior one-third CCA for completion of a prior partial CCA (22.22%, n = 20), complete CCA (27.78%, n = 25), or CCA of residual white matter in the case of subtotal initial ablation (5.56%, n = 5). Overall, 12.94% of the patients undergoing CCA experienced operational complications. The most common operative complications across 90 CCA operations were probe malpositioning (n = 6), hemorrhage (n = 5), off-target extension of splenium ablation to the thalamus (n = 1), infection (n = 1), and postoperative CSF leak (n = 1). Neurological deficits following CCA were reported as transient in 18.82% and permanent in 4.71% of patients across all studies. The most common neurological deficits were disconnection syndrome (n = 4) or transient hemiplegia (supplementary motor area-like syndrome; n = 4). The 6-month overall seizure freedom rate was 18.87% of 53 patients, and the atonic seizure freedom rate was 46.28% of 52 patients postoperatively. CCA resulted in an average decrease in atonic seizure rate from 8.30 to 1.65 atonic seizures per day (average decrease 80.12%). CCA is associated with an acceptable complication profile, and most patients experience a meaningful reduction in target seizure semiologies. Accurate MRgLITT probe placement is likely important for maximizing CCA while avoiding collateral damage. Avoidable complications of CCA include off-target ablation (and associated deficits), hemorrhage, and future surgery for residual CCA to palliate continued seizures.

Study protocol for a multicenter randomised controlled trial on the (cost)effectiveness of biopsy combined with same-session MR-guided LITT versus biopsy alone in patients with primary irresectable glioblastoma (EMITT trial)

BackgroundGlioblastoma (GBM) is the most common primary, malignant brain tumour with a 5-year survival of 5%. If possible, a glioblastoma is resected and further treated with chemoradiation therapy (CRT), but resection is not feasible in about 30% of cases. Current standard of care in these cases is a biopsy followed by CRT. Magnetic resonance (MR) imaging-guided laser interstitial thermal therapy (LITT) has been suggested as a minimally invasive alternative when surgery is not feasible. However, high-quality evidence directly comparing LITT with standard of care is lacking, precluding any conclusions on (cost-)effectiveness. We therefore propose a multicenter randomized controlled study to assess the (cost-)effectiveness of MR-guided LITT as compared to current standard of care (EMITT trial).Methods and analysisThe EMITT trial will be a multicenter pragmatic randomized controlled trial in the Netherlands. Seven Dutch hospitals will participate in this study. In total 238 patients will be randomized with 1:1 allocation to receive either biopsy combined with same-session MR-guided LITT therapy followed by CRT or the current standard of care being biopsy followed by CRT. The primary outcomes will be health-related quality of life (HR-QoL) (non-inferiority) using EORTC QLQ-C30 + BN20 scores at 5 months after randomization and overall survival (superiority). Secondary outcomes comprise cost-effectiveness (healthcare and societal perspective) and HR-QoL of life over an 18-month time horizon, progression free survival, tumour response, disease specific survival, longitudinal effects, effects on adjuvant treatment, ablation percentage and complication rates.DiscussionThe EMITT trial will be the first RCT on the effectiveness of LITT in patients with glioblastoma as compared with current standard of care. Together with the Dutch Brain Tumour Patient association, we hypothesize that LITT may improve overall survival without substantially affecting patients’ quality of life.Trial registrationThis trial is registered at ClinicalTrials.gov (NCT05318612).

A cost analysis of MR-guided laser interstitial thermal therapy for adult refractory epilepsy.

MR-guided laser interstitial thermal therapy (LITT) is used increasingly for refractory epilepsy. The goal of this investigation is to directly compare cost and short-term adverse outcomes for adult refractory epilepsy treated with temporal lobectomy and LITT, as well as to identify risk factors for increased costs and adverse outcomes. The National Inpatient Sample (NIS) was queried for patients who received LITT between 2012 and 2019. Patients with adult refractory epilepsy were identified. Multivariable mixed-effects models were used to analyze predictors of cost, length of stay (LOS), and complications. LITT was associated with reduced LOS and overall cost relative to temporal lobectomy, with a statistical trend toward lower incidence of postoperative complications. High-volume surgical epilepsy centers had lower LOS overall. Longer LOS was a significant driver of increased cost for LITT, and higher comorbidity was associated with non-routine discharge. LITT is an affordable alternative to temporal lobectomy for adult refractory epilepsy with an insignificant reduction in inpatient complications. Patients may benefit from expanded access to this treatment modality for both its reduced LOS and lower cost.

Improved MR temperature imaging at 0.5T using view-sharing accelerated multiecho thermometry for MR-guided laser interstitial thermal therapy.

The aim of the current study was to improve temperature-monitoring precision using multiecho proton resonance frequency shift-based thermometry with view-sharing acceleration for MR-guided laser interstitial thermal therapy (MRgLITT) on a 0.5-T low-field MR system. Both precision and speed of the temperature measurement for clinical MRgLITT treatments suffer at low field, due to reduced image signal-to-noise ratio (SNR), decreased temperature-induced phase changes, and limited RF receiver channels. In this work, a bipolar multiecho gradient-recalled echo sequence with a temperature-to-noise ratio optimal weighted echo combination is applied to improve the temperature precision. A view-sharing-based approach is utilized to accelerate signal acquisitions while preserving image SNRs. The method was evaluated using ex vivo (pork and pig brain) LITT heating experiments and in vivo (human brain) nonheating experiments on a high-performance 0.5-T scanner. In terms of results, (1) after echo combination, multiecho thermometry (i.e., ~7.5-40.5ms, 7 TEs) provides ~1.5-1.9 times higher temperature precision than the no echo combination case (i.e., TE7 = 40.5ms) within the same readout bandwidth. Additionally, echo registration is necessary for the bipolar multiecho sequence; (2) for a threefold acceleration, the view-sharing approach with variable-density subsampling shows around 1.8 times lower temperature errors than the GRAPPA method. Particularly for view-sharing, variable-density subsampling performs better than Interleave subsampling; and (3) ex vivo heating and in vivo nonheating experiments demonstrated that the temperature accuracy was less than 0.5 and that the temperature precision was less than 0.6 using the proposed 0.5-T thermometry. It was concluded that view-sharing accelerated multiecho thermometry is a practical temperature measurement approach for MRgLITT at 0.5T.

Apparent diffusion coefficient of piriform cortex and seizure outcome in mesial temporal lobe epilepsy after MR-guided laser interstitial thermal therapy: a single-institution experience.

Piriform cortex (PC) is one of the critical structures in the epileptogenesis of mesial temporal lobe epilepsy (mTLE), but its role is poorly understood. The authors examined the utility of apparent diffusion coefficient (ADC; an MR-based marker of tissue pathology) of the PC as a predictor of seizure outcome in patients with mTLE undergoing MR-guided laser interstitial thermal therapy (MRgLITT). A total of 33 patients diagnosed with mTLE who underwent MRgLITT at the authors' institution were included in the study. The 6-month postoperative seizure outcomes were classified using the International League Against Epilepsy (ILAE) system as good (complete seizure freedom, ILAE class I) and poor (seizure present, ILAE classes II-VI). The PC and ablation volumes were manually segmented from both the preoperative and intraoperative MRI sequences, respectively. The mean ADC intensities of 1) preablation PC; 2) total ablation volume; 3) ablated portion of PC; and 4) postablation residual PC were calculated and compared between good and poor outcome groups. Additionally, the preoperative PC volumes and proportion of PC volume ablated were examined and compared between the subjects in the two outcome groups. The mean age at surgery was 36.5 ± 3.0 years, and the mean follow-up duration was 1.9 ± 0.2 years. Thirteen patients (39.4%) had a good outcome. The proportion of PC ablated was significantly associated with seizure outcome (10.16 vs 3.30, p < 0.05). After accounting for the variability in diffusion tensor imaging acquisition parameters, patients with good outcome had a significantly higher mean ADC of the preablation PC (0.3770 vs -0.0108, p < 0.05) and the postoperative residual PC (0.4197 vs 0.0309, p < 0.05) regions compared to those with poor outcomes. No significant differences in ADC of the ablated portion of PC were observed (0.2758 vs -0.4628, p = 0.12) after performing multivariate analysis. A higher proportion of PC ablated was associated with complete seizure freedom. Preoperative and postoperative residual ADC measures of PC were significantly higher in the good seizure outcome group in patients with mTLE who underwent MRgLITT, suggesting that ADC analysis can assist with postablation outcome prediction and patient stratification.

NFB-06. Laser Interstitial Thermal Therapy as a Radiation-Sparing Approach for Children with Cancer Predisposition

BACKGROUND: Li-Fraumeni (LFS) syndrome confers a predisposition for the formation of a broad range of tumors. Estimates of post-radiation secondary malignancy in the context of LFS cohorts range from 20-50%. Therefore, alternative therapeutic strategies are prioritized. Laser interstitial thermal therapy (LITT) is a minimally invasive technique utilizing thermal ablation for tumor control that is not associated with any ionizing radiation or known mutagenic effect. We describe the case of a child with LFS previously treated for CPC who developed a secondary low-grade glial neoplasm of the brain treated safely with MR-guided LITT as part of a radiation-sparing therapeutic approach. METHODS: Retrospective chart review identified a patient with recurrent CPC associated with LFS who was treated with LITT for a secondary low-grade glial tumor. A descriptive report is provided, including a review of clinical and radiologic outcomes of the procedure. RESULTS: A 4-year-old male with left parietal WHO Grade III CPC associated with a TP53 germline mutation met inclusion criteria. The patient underwent neoadjuvant platinum-based chemotherapy before near-total resection, followed by immunotherapy with 131I-8H9 and 30 fractions of 54Gy total proton therapy. He remained without evidence of disease for two years prior to developing a slow-growing mass adjacent to the left frontal horn. This lesion demonstrated radiographic progression on neuroimaging and was deemed to be a poor candidate for surgical removal. Stereotactic biopsy revealed a low-grade glial neoplasm staining positive for GFAP and Olig2. MR-guided LITT was concurrently performed for ablative therapy of the lesion without complication. Greater than 8-month follow-up has revealed no subsequent disease. CONCLUSIONS: Alternatives to ionizing radiation for brain tumors should be explored for patients with cancer predisposition, such as LFS. Long-term follow up will be needed to ensure local disease control and avoidance of treatment-related neoplasms.

Piriform Cortex Ablation Volume Is Associated With Seizure Outcome in Mesial Temporal Lobe Epilepsy

Growing evidence suggests that piriform cortex resection during anterior temporal lobectomy is important for achieving good seizure outcome in mesial temporal lobe epilepsy (mTLE). However, the relationship between seizure outcome and piriform cortex ablation during MR-guided laser interstitial thermal therapy (MRgLITT) remains unclear. To determine whether ablation of piriform cortex was associated with seizure outcome in patients with mTLE undergoing MRgLITT. We performed preablation and postablation volumetric analyses of hippocampus, amygdala, piriform cortex, and ablation volumes in patients with mTLE who underwent MRgLITT at our institution from 2014 to 2019. Thirty nine patients with mTLE were analyzed. In univariate logistic regression, percent piriform cortex ablation was associated with International League Against Epilepsy (ILAE) class 1 at 6 months (odds ratio [OR] 1.051, 95% CI [1.001-1.117], P = .045), whereas ablation volume, percent amygdala ablation, and percent hippocampus ablation were not ( P > .05). At 1 year, ablation volume was associated with ILAE class 1 (OR 1.608, 95% CI [1.071-2.571], P = .021) while percent piriform cortex ablation became a trend (OR 1.050, 95% CI [0.994-1.109], P = .054), and both percent hippocampus ablation and percent amygdala ablation were not significantly associated with ILAE class 1 ( P > .05). In multivariable logistic regression, only percent piriform cortex ablation was a significant predictor of seizure freedom at 6 months (OR 1.085, 95% CI [1.012-1.193], P = .019) and at 1 year (OR 1.074, 95% CI [1.003-1.178], P = .041). Piriform cortex ablation volume is associated with seizure outcome in patients with mTLE undergoing MRgLITT. The piriform cortex should be considered a high yield ablation target to achieve good seizure outcome.

Magnetic resonance-guided laser interstitial thermal therapy for pediatric periventricular nodular heterotopia-related epilepsy.

Periventricular nodular heterotopia (PVNH) is a result of disrupted neuronal migration from the ventricular system and can be a rare cause of refractory focal epilepsy. The goal of this case series was to describe the treatment of pediatric PVNH-related epilepsy with MR-guided laser interstitial thermal ablation. Patients treated at a single institution with MR-guided laser interstitial thermal therapy (MRgLITT) for PVNH-related epilepsy were identified. Preoperative and postoperative seizure outcomes and procedural information were evaluated. Five children with PVNH treated with MRgLITT were reviewed; 1 child was treated twice. Three patients were female; the median age was 10.9 years. Five of 6 treatments were preceded by stereoelectroencephalography phase II monitoring. Three children experienced unilateral PVNH, and 2 had bilateral seizures. The median number of seizures recorded during phase II monitoring was 2; the median number of ablation targets was 2 (range 1-4). All patients experienced a decrease in seizure frequency; 4 patients (80%) had an Engel class ≤ III at the last follow-up (range I-IV). One child experienced right hemianopia posttreatment. This case series investigation has illustrated a novel, minimally invasive approach for treating pediatric PVNH-related epilepsy. Further study of this technique with comparison with other surgical techniques is warranted.

Stereotactic laser interstitial thermal therapy corpus callosotomy for the treatment of pediatric drug-resistant epilepsy.

ObjectiveCorpus callosotomy is a safe and effective procedure for reducing the frequency of drop attacks. MR‐guided laser interstitial thermal therapy (MRgLITT) offers a minimally invasive alternative to conventional open craniotomy for callosotomy. We hypothesized that MRgLITT callosotomy could be safely performed in pediatric patients with similar seizure control.MethodsWe present an institutional case series of 11 procedures in 10 patients for the treatment of drop attacks in drug‐refractory primary generalized epilepsy. MRgLITT was used for complete callosotomy, anterior two‐thirds, posterior, or ablation of residual callosal fibers following prior callosotomy (open or MRgLITT). We retrospectively reviewed clinical course, operative details, radiographic imaging, clinical outcomes, and complications.ResultsOperative time ranged from 4‐8 hours, and median hospitalization was 2 days. No complications were encountered. Among the 7 patients with at least 3 months of follow‐up, 71% experienced freedom from drop attacks at longest follow‐up and 57% of cases showed improvement in their other seizure semiologies as well (Engel Class II: 28%, Class III: 28%, Class IV: 43%).SignificanceMR‐guided LITT callosotomy is safe and effective modality in the management of pediatric patients with medically intractable epilepsy characterized by drop attacks. While this is among the largest pediatric series to date, further studies are required to delineate its safety and efficacy among such patients.

Surgical outcomes in children with bottom-of-sulcus dysplasia and drug-resistant epilepsy: a retrospective cohort study.

Bottom-of-sulcus dysplasia (BOSD) is challenging to identify radiologically. The aim of this study was to explore seizure outcomes after resective surgery or MR-guided laser interstitial thermal therapy (MRgLITT) in children with BOSD. Children with radiologically defined BOSD who underwent resective surgery or MRgLITT, with at least 1 year of follow-up were included. Clinical, radiological, neurophysiological, and histological data were extracted from medical records. Invasive video EEG (IVEEG) was used to evaluate the ictal onset zone or motor/language mapping, wherever appropriate. Histology of MRI-visible BOSD, including the overlying and adjacent cortex, was also evaluated. Forty-one children with BOSD underwent surgical treatment. The lesion was initially overlooked on MRI in 20 patients (48.8%). Of 34 patients who underwent IVEEG and who had available ictal data, the ictal onset zone extended beyond the MRI-visible BOSD in 23 patients (67.6%). Surgical treatment included lesionectomy (24 patients), extended lesionectomy (12 patients), lobectomy (1 patient), and ablation of BOSD (4 patients). The pathology in 37 patients who underwent resection showed focal cortical dysplasia type IIB and type IIA in 21 (53.8%) and 16 patients (41%), respectively. Seizure freedom was achieved in 32 patients (78.1%) after a mean follow-up of 4.3 years. Seizure outcomes after resective surgery or MRgLITT in children with BOSD were generally favorable. The authors found that the neurophysiological abnormality and pathology often extended beyond the MRI-visible BOSD.

Adopting MR-guided stereotactic laser ablations for epileptic lesions: initial clinical experience and lessons learned.

MR-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive technique for ablating brain lesions under real-time MRI feedback and control of the ablation process. The Medtronic Visualase system was recently approved for use in Europe and Israel. We report our initial technical experience using the system in the first 16 cases in which the system was used to ablate focal epileptogenic lesions. We included all consecutive patients with intractable epilepsy who underwent MRgLITT procedures between 2018 and 2020. We reviewed medical charts and imaging studies of patients. Post-ablation MRIs were used to calculate ablation volumes. Seventeen MRgLITT procedures were performed in 16 patients. One cooling catheter/laser fiber assemblies were placed per patient. Indications for surgery were intractable epilepsy due to TLE (n = 7),suspected low-grade glioma (n = 4), radiological cortical dysplasia (n = 1), hypothalamic hamartoma (n = 1), and MR-negative foci (n = 3). Ablations were made using 30 to 70% of the maximal energy of the Visualase system. We used serial ablations as needed along the tract of the catheter by pulling back the optic fiber; the length of the lesion ranged between 7.4 and 38.1mm. Ablation volume ranged between 0.27 and 6.78 mm3. Immediate post-ablation MRI demonstrated good ablation of the epileptic lesion in 16/17 cases. In one case with mesial temporal sclerosis, no ablation was performed due to suboptimal position of the catheter. That patient was successfully reoperated at a later date. Mean follow-up was 14.9months (± 11.6months). Eleven patients had follow-up longer than 12months. Good seizure control (Engel I, A) was achieved in 7/11 patients (63%) and 1/11 (9%) had significant improvement in seizure frequency (Angle IIIa). Three patients (27%) did not experience improvement in their seizure frequency (Engel IV, B), and one of these patients died during the follow-up period from sudden unexpected death of epilepsy (SUDEP). No immediate or delayed neurological complications were documented in any of the cases during the follow-up period. MRgLITT is a promising technique and can be used safely as an alternative to open resection in both lesional and non-lesional intractable epilepsy cases. In our local series, the success rate of epilepsy surgery was comparable to recent publications.

Retrospective analysis of open surgical versus laser interstitial thermal therapy callosotomy in pediatric patients with refractory epilepsy.

Corpus callosotomy remains an established surgical treatment for certain types of medically refractory epilepsy in pediatric patients. While the traditional surgical approach is often well tolerated, the advent of MR-guided laser interstitial thermal therapy (LITT) provides a new opportunity to ablate the callosal body in a minimally invasive fashion and minimize the risks associated with an open interhemispheric approach. However, the literature is sparse regarding the comparative efficacy and safety profiles of open corpus callosotomy (OCC) and LITT callosotomy. To this end, the authors present a novel retrospective analysis comparing the efficacy and safety of these methods. Patients who underwent OCC and LITT callosotomy during the period from 2005 to 2018 were included in a single-center retrospective analysis. Patient demographic and procedural variables were collected, including length of stay, procedural blood loss, corticosteroid requirements, postsurgical complications, and postoperative disposition. Pre- and postoperative seizure frequency (according to seizure type) were recorded. In total, 19 patients, who underwent 24 interventions (16 OCC and 8 LITT), were included in the analysis. The mean follow-up durations for the OCC and LITT cohorts were 83.5 months and 12.3 months, respectively. Both groups experienced reduced frequencies of seizure and drop attack frequency postoperatively. Additionally, LITT callosotomy was associated with a significant decrease in estimated blood loss and decreased length of pediatric ICU stay, with a trend of shorter length of hospitalization. Longer-term follow-up and a larger population are required to further delineate the comparative efficacies of LITT callosotomy and OCC for the treatment of pediatric medically refractory epilepsy. However, the authors' data demonstrate that LITT shows promise as a safe and effective alternative to OCC.

Surgical targeting of large hypothalamic hamartomas and seizure-freedom following MR-guided laser interstitial thermal therapy

BackgroundLarge hypothalamic hamartomas (HH) are often associated with difficult-to-treat, refractory seizures. Although magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) has emerged as a useful tool to treat these challenging lesions, postoperative outcomes are variable and potentially related to differences in surgical targeting. PurposeWe sought to identify differences in the anatomic localization of laser ablations that either did or did not result in seizure freedom. MethodsFour children who underwent MRgLITT for large HH (3 seizure-free and 1 not seizure-free) were included in the analysis. Ablation volumes were segmented, normalized, and overlaid on a high-resolution hypothalamic atlas. For each lesion, the size, spatial extent, and degree of overlap with key hypothalamic nuclei and surrounding brain regions were computed and compared between ablations that did and did not result in seizure freedom. ResultsAblation masks that resulted in seizure freedom were smaller and located more centrally than the ablation mask that did not. In addition, ablation masks that resulted in seizure freedom overlapped with regions including the paraventricular nucleus, the posterior hypothalamus and the zona incerta, fornix, and mammillothalamic tract, whereas the single non-seizure-free ablation did not. ConclusionDifferences in the size, position, and anatomical localization of ablation volumes may be a potential contributor to the variability in postoperative outcomes of large HH treated with MRgLITT. A novel, high-resolution MRI atlas of the hypothalamus identifies a number of regions at the interface of large HH that are preferentially disconnected in seizure-free patients. This method of anatomical localization not only serves as a potential clinical tool for surgical targeting but may also provide novel insights into the mechanisms of epileptogenesis in hypothalamic hamartomas.

Magnetic resonance-guided laser interstitial thermal therapy for brain tumors in geriatric patients.

There is a paucity of studies assessing the use of MR-guided laser interstitial thermal therapy (LITT), specifically in the elderly population. The aim of this study was to evaluate the safety of LITT for brain tumors in geriatric patients. Geriatric patients (≥ 65 years of age) treated with LITT for intracranial tumors at a single institution between January 2011 and November 2019 were retrospectively identified. The authors grouped patients into two distinct age cohorts: 65-74 years (group 1) and 75 years or older (group 2). Baseline characteristics, operative parameters, postoperative course, and morbidity were recorded for each patient. Fifty-five geriatric patients underwent 64 distinct LITT procedures for brain tumors. The majority of lesions (40 [62.5%]) treated were recurrent brain metastases or radiation necrosis. The median modified frailty index was 0.1 (low frailty; range 0-0.4) for patients in group 1 and 0.2 (intermediate frailty; range 0-0.4) for patients in group 2 (p > 0.05). The median hospital length of stay (LOS) was 1 day (IQR 1-2 days); there was no significant difference in LOS between the age groups. The hospital stay was significantly longer in patients who presented with a neurological symptom and in those who experienced a postoperative complication. The majority of patients (43 [68.3%] of 63 cases) were fit for discharge to their preoperative accommodation following LITT. The rate of discharge to home was not significantly different between the age groups. Those discharged to rehabilitation facilities were more likely to have presented with a neurological symptom. Nine patients (14.1% of cases) were found to have acute neurological complications following LITT, with nearly all patients showing complete or partial recovery at follow-up. The 30-day postoperative mortality rate was 1.6% (1 case). The complication and 30-day postoperative mortality rates were not significantly different between the two age groups. LITT can be considered a minimally invasive and safe neurosurgical procedure for the treatment of intracranial tumors in geriatric patients. Careful preoperative preparation and postoperative care is essential as LITT is not without risk. Appropriate patient selection for cranial surgery is essential, because neurosurgeons are treating an increasing number of elderly patients, but advanced age alone should not exclude patients from LITT without considering frailty and comorbidities.

Presurgical epilepsy evaluation and epilepsy surgery.

With a prevalence of 0.8 to 1.2%, epilepsy represents one of the most frequent chronic neurological disorders; 30 to 40% of patients suffer from drug-resistant epilepsy (that is, seizures cannot be controlled adequately with antiepileptic drugs). Epilepsy surgery represents a valuable treatment option for 10 to 50% of these patients. Epilepsy surgery aims to control seizures by resection of the epileptogenic tissue while avoiding neuropsychological and other neurological deficits by sparing essential brain areas. The most common histopathological findings in epilepsy surgery specimens are hippocampal sclerosis in adults and focal cortical dysplasia in children. Whereas presurgical evaluations and surgeries in patients with mesial temporal sclerosis and benign tumors recently decreased in most centers, non-lesional patients, patients requiring intracranial recordings, and neocortical resections increased. Recent developments in neurophysiological techniques (high-density electroencephalography [EEG], magnetoencephalography, electrical and magnetic source imaging, EEG-functional magnetic resonance imaging [EEG-fMRI], and recording of pathological high-frequency oscillations), structural magnetic resonance imaging (MRI) (ultra-high-field imaging at 7 Tesla, novel imaging acquisition protocols, and advanced image analysis [post-processing] techniques), functional imaging (positron emission tomography and single-photon emission computed tomography co-registered to MRI), and fMRI significantly improved non-invasive presurgical evaluation and have opened the option of epilepsy surgery to patients previously not considered surgical candidates. Technical improvements of resective surgery techniques facilitate successful and safe operations in highly delicate brain areas like the perisylvian area in operculoinsular epilepsy. Novel less-invasive surgical techniques include stereotactic radiosurgery, MR-guided laser interstitial thermal therapy, and stereotactic intracerebral EEG-guided radiofrequency thermocoagulation.

SURG-05. LASER INTERSTITIAL THERMAL THERAPY FOR MELANOMA BRAIN METASTASIS: A CASE SERIES

Stereotactic radiosurgery (SRS) and whole brain radiation therapy (WBRT) have been established as non-invasive treatment modalities for intracranial metastasis from malignant melanoma, with SRS emerging as a safe and effective stand along therapy. However, either due to tumor regrowth or radiation necrosis, these radiation modalities can fail. MR-guided laser interstitial thermal therapy (LITT) has emerged as an option for these tumors. Clinical data for five patients at our institution was retrospectively reviewed. These were all the patients that had undergone LITT for intracranial metastatic melanoma after prior treatment failure that included a radiation modality. Demographics, prior treatments, surgical data, perioperative complications, adjuvant treatments, and follow imaging data were gathered. Of the five patients, one patient had received WBRT, three patients had received prior SRS to the area that underwent LITT, and one patient had a prior craniotomy with adjuvant SRS. Two of the tumors were located in the premotor area (frontal lobe), two tumors were located in the motor strip, and one tumor was located in the cerebellum. The average tumor volume was 4.32 cc (range 1.86 - 7.84 cc). Median time of hospital stay was 2 days (with a 2.6 day average). No perioperative complications were encountered. Three of the patients had received adjuvant therapy at our institution; these patients were not delayed in receiving adjuvant therapy. Of these three patients, only one patient had a BRAF mutation detected. Four patients received follow up imaging at our institution, with no patients demonstrating tumor regrowth in the site of LITT. Regrowth of intracranial metastasis of malignant melanoma is a known possibility of traditional radiation therapies. LITT should be considered as a safe, effective option for those that fail these traditional therapies, especially those located in areas difficult to access. The low complication rate allows patients to restart adjuvant therapies.

MR-Guided Laser Interstitial Thermal Therapy for Medically Refractory Lesional Epilepsy in Pediatric Patients: Experience and Outcomes

Introduction: MR-guided laser interstitial thermal therapy (MRgLITT) has emerged as a safe and effective treatment option for the ablation of epileptic foci. Its minimally invasive nature makes it attractive due to decreased morbidity and hospital stay. Objective: To report the efficacy and safety of MRgLITT as a minimally invasive procedure for the ablation of epileptic foci in the pediatric population of medically refractory lesional epilepsy. Methods: A retrospective review of patients who underwent MRgLITT via Visualase laser ablation at a single pediatric center was performed. Demographic and outcome data were compiled and analyzed. Results: Twelve pediatric patients with a total 18 lesions underwent MRgLITT procedures between December 2013 and September 2017. Mean age at surgery was 11.1 years. Surgical substrates included 4 hypothalamic hamartomas, 3 periventricular heterotopias, 2 deep focal cortical dysplasias, 2 tuberous sclerosis, and 1 mesial temporal sclerosis. Methods of stereotaxis used included Leksell frame, BrainLab VarioGuide, ROSA robot guidance, and ClearPoint navigation. Mean procedure length was 250 min, and mean length of stay was 1.3 days. After treatment, 8 patients were seizure free (Engel I, 66.7%), 2 patients demonstrated significant improvement (Engel II, 16.7%), and 2 patients showed worthwhile improvement (Engel III, 16.7%). One patient developed a left superior quadrantanopsia postoperatively. Mean follow-up duration was 10 months. Conclusion: This study contributes to the sparse literature in this field by demonstrating the high efficacy and low morbidity of MRgLITT as a minimally invasive method of ablation of epileptic foci in the pediatric population of medically refractory lesional epilepsy.

Imaging of Laser Therapy in Epilepsy.

MR-guided laser interstitial thermal therapy (MRgLITT) is an increasingly popular neuroablative method for the surgical treatment of epilepsy patients. This article intends to demonstrate the utility and pitfalls of imaging in the context of patient care with MRgLITT. A retrospective review of the medical records and imaging database with six illustrative cases selected to demonstrate the use of imaging throughout patient management with MRgLITT in diverse clinical situations and pathologies. A review of the knowledge in the literature was applied to the relevant points discussed. Imaging findings were described in the setting of laser therapy in nonlesional epilepsy, mesial temporal sclerosis, dual pathology, periventricular nodular heterotopia, and schizencephaly. Discussion of imaging principles, potential pitfalls, as well as its use in the patient work-up and follow-up, is shown. MRgLITT is an alternative minimally invasive therapy for refractory epilepsy, which is becoming widely sought for. Imaging plays a crucial role prior to, during, and after the procedure.