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Magnetic resonance thermography−guided laser interstitial thermal therapy (LITT) provides a minimally invasive treatment option in children with central nervous system tumors or medically intractable epilepsy. However, transporting anesthetized children between an operating room (OR) and a radiologic suite creates logistical challenges. Thus we describe advantages of using a 2-room intraoperative magnetic resonance imaging (MRI) concept for LITT. Patients were pinned in a head frame that doubles as the lower part of the MRI head coil. Preoperative MRI was performed for accurate neuronavigation, after which laser fibers were stereotactically implanted. Transport between OR and MRI was achieved by sliding the top of the OR table onto a trolly. We performed 12 procedures in 11 children, mean age 7.1 years (range: 2 to 14 years). Ten children suffered from medically intractable epilepsy, and 1 child had a pilocytic midbrain astrocytoma. Two fibers were placed in 8 and 1 fiber in 4 procedures. Mean entry point and target errors were 2.8 mm and 3.4 mm, respectively. Average transfer time from OR to MRI and vice versa was 9 minutes (±1 minute, 40 seconds). Altogether, 50% of the seizure patients were seizure free (Engel grade I) at 22 months' follow-up time. One hemorrhagic event, which could be managed nonoperatively, occurred. We recorded no surgical site or intracranial infections. All LITT procedures were successfully carried out with head frame in the sterile environment. The intraoperative MRI suite proved to be advantageous for minimally invasive procedures, especially in young children resulting in short transports while maintaining high accuracy and safety. [ABSTRACT FROM AUTHOR]

Temporal lobe encephaloceles (TEs) are a rare cause of drug-resistant temporal lobe epilepsy (DR-TLE), with head trauma and obesity identified as risk factors in adults. This study evaluated the clinical characteristics of childhood-onset DR-TLE due to TE. This is a single-institution retrospective review of childhood-onset DR-TLE with radiographic TE identified between 2008 and 2020. The epilepsy history, brain imaging features, and surgical outcomes were collected. Eleven children with DR-TLE due to TE were included (median age at epilepsy onset was 11 years, interquartile range 8.5 to 13.5 years). Median latency between epilepsy diagnosis and TE detection was 3 years (range of 0 to 13 years). None had history of head trauma. Body mass index greater than 85 percentile for age and sex was seen in 36% of the children. No patient had bilateral TE identified. TEs were diagnosed based on epilepsy surgery conference re-review of imaging in 36% of cases. All herniations were contained defects without osseous dehiscence. Regional fluorodeoxyglucose (FDG) hypometabolism ipsilateral to the encephalocele was seen in all children who had FDG-positron emission tomography (PET) of the brain. Of the children who had surgery, 70% were seizure free or had nondisabling seizures at last follow-up (mean follow-up 52 months). TE is a surgically remediable etiology of DR-TLE in childhood. TEs are often overlooked at pediatric epilepsy diagnosis, calling for the need to increase awareness of this entity. FDG-PET temporal hypometabolism in children with presumed nonlesional DR-TLE should be carefully examined for occult TEs. [ABSTRACT FROM AUTHOR]

Anteromesial resection is an effective method for treating seizures arising from the medial temporal lobe, as these cases are often the most straightforward and have the best outcomes. Nevertheless, some patients who go on to have a mesial resection are recommended to have an implantation of electrodes before surgery. Whether the need for such an implant alters the rate of seizure freedom is not well-studied in this particular subgroup of epilepsy patients. We performed a retrospective review of consecutive anteromesial surgeries for medial temporal lobe epilepsy performed between 2005 and 2020. Of a total of 39 patients, 19 required electrode implantation (electrode group) and 20 did not (no-electrode group). The primary outcomes assessed were reduction in seizure frequency and Engel score. Complication rates were also compared. Postresection seizure frequency reduction was nonsignificantly higher in the no-electrode group (97.0 ± 10.3%) than in the electrode group (88.5 ± 23.7%, P = 0.15). The rate of Engel I outcome was nonsignificantly higher in the no-electrode group (84.2%) than in the electrode group (65.0%, P = 0.17). Major complication rates were nonsignificantly higher in the no-electrode group (15.8 ± 1.9%) than in the electrode group (5.0 ± 1.1%, P = 0.26). Power analysis revealed that 74 patients would need to be included in each group to reach statistical significance. Although not statistically significant, our study showed a trend for improved seizure control if a decision was made not to implant electrodes prior to potentially curative anteromesial resection. Engel I outcome in this group reached approximately 85%. A larger multi-instiutional study may be required to reach statistical significance. [ABSTRACT FROM AUTHOR]

Magnetic resonance imaging–guided laser interstitial therapy (MrLITT) presents a new valuable treatment alternative when the in-field recurrence (IFR) of metastatic brain tumors is difficult to safely access with open surgery or maximum radiation therapy has already been completed. To examine the effects of MrLITT on longevity outcomes based on volume of ablation. A retrospective study was carried out of 35 patients treated with MrLITT for IFR after radiosurgery for metastatic brain tumors at a single institution from 2010 to 2016. Overall survival (OS) and progression-free survival (PFS) were analyzed with Kaplan-Meier and Cox regression analyses according to ablation volume. Univariate and multivariate analyses further assessed risk factors based on ablation volume. Kaplan-Meier analyses showed no significant differences between total and subtotal ablation groups in OS (61.1 vs. 49.7 weeks) and PFS (45.1 and 42.7 weeks), respectively (P > 0.05). In the subtotal ablation group, independent risk factors included preoperative tumor volume (hazard ratio [HR], 1.24; P = 0.05) for OS and residual tumor volume (HR, 2.62; P = 0.01) for PFS. Multivariate Cox regressions suggested no significant differences in OS (HR, 1.03; P = 0.19) and PFS (HR, 1.02; P = 0.24) between total and subtotal ablation groups, whereas preoperative tumor volume remained a risk factor for decreased OS (HR, 1.23; P = 0.004). MrLITT is an effective treatment option for IFR after radiosurgery for metastatic brain tumors. The benefits of more aggressive gross total ablations of deep targets near eloquent cortices are limited compared with effective subtotal ablations, but the amount of residual tumor volume left must be appropriately balanced. [ABSTRACT FROM AUTHOR]

Laser interstitial thermal therapy (LITT) is an emerging treatment modality for both primary brain tumors and metastases. We report initial outcomes after LITT for metastatic brain tumors across 3 sites at our institution and discuss potential strategies for optimal patient selection and outcomes. International Classification of Diseases, Ninth Revision and Tenth Revision codes were used to identify patients with malignant brain tumors treated via LITT across all 3 Mayo Clinic sites with at least 6 months follow-up. Local control was based on radiologic and clinical evidence. Overall survival was measured from time of receiving LITT until death or end of the study period. Twenty-three patients were treated for progression of a single (n = 21) or multiple (n = 2) previously radiated metastatic lesions and/or radiation necrosis. Median age was 56 years (interquartile range, 47–66.5 years). LITT achieved local control of the lesion in most patients with metastatic tumors or radiation necrosis (n = 18; 81.8%) for the duration of follow-up. One patient did not have local control data available. Thirteen (56.5%) patients remained alive at the end of the study period. No other patients died of their treated disease during the study period; 5 of 10 deaths were attributable to central nervous system progression outside the treated lesion. Although median survival for this cohort has not yet been reached, the current median survival is 16 months (interquartile range, 12–48.5 months) after LITT for metastatic/radiation necrosis lesions. LITT was associated with sustained local control in 81.8% of patients treated for radiographic progression of metastatic central nervous system disease. [ABSTRACT FROM AUTHOR]

There has been a paradigm shift in the management of hypothalamic hamartoma (HH) from traditional microsurgical techniques to less invasive alternatives. However, large and extensive HH may fail to respond to these therapies, necessitating craniotomies. All patients who underwent microsurgical resection of a complex HH by the 2 senior authors from 2011 to 2021 were included. Charts were retrospectively reviewed and demographic, clinical, imaging, and outcome data were recorded. Eight patients (mean age, 7 years) were included. Two had failed previous treatments. All 7 presented with gelastic seizures and cognitive dysfunction, 6 showed central precocious puberty, and 3 had behavioral problems. The mean lesion size was 21.6 mm and all had interpeduncular extension, 5 had intraventricular extension (Delalande type I, 3; type III, 4; type IV, 1). A frontotemporal orbitozygomatic approach with optic nerve decompression was used in all patients, supplemented by another approach in 3 (endoscopic transventricular, 3; transcallosal, 1). Gross total resection was achieved in 6 patients and subtotal resection in 2. Transient complications occurred in 3 patients (37.5%): self-limited sodium imbalance (n = 3), subdural hygroma (n = 2). Permanent complications occurred in 2 patients (25%): perforator infarct (n = 1) and short-term memory loss (n = 1). All patients experienced seizure resolution with preserved hypothalamic-pituitary axis function. After a mean follow-up of 41 months (range, 2–66 months), 7 patients remained seizure free, and 1 had rare seizures. Cognitive and behavioral symptoms improved in all patients. For large HH with interpeduncular extension, microsurgery via the frontotemporal orbitozygomatic approach is a safe and highly effective treatment modality. [ABSTRACT FROM AUTHOR]

Laser interstitial thermal therapy (LITT) is a minimally invasive alternative to anterior temporal lobectomy (ATL) for treatment of temporal lobe epilepsy. It has gained popularity as familiarity with technique increases and outcomes are better characterized. There has been no direct cost comparison between the 2 techniques in literature to date. The current study directly compares hospital costs associated with LITT with those of ATL patients and analyzes the factors potentially responsible for those costs. Patients who underwent ATL (27) and LITT (15) were retrospectively reviewed for total hospital costs along with demographic, surgical, and postoperative factors potentially affecting cost. T-tests were used to compare costs and independent linear regressions, and hierarchical regressions were used to examine predictors of cost for each procedure. Mean hospital costs of admission for single-trajectory LITT ($104,929.88) were significantly less than for ATL ($134,980.04) (P = 0.001). In addition, length of stay, anesthesia costs, operative room costs, and postoperative hospitalization costs were all significantly lower in LITT. Given the minimally invasive nature of LITT, it is associated with shorter length of stay and lower hospital costs than ATL in the first head-to-head comparison of procedural costs in literature to date. Long-term efficacy as it relates to these costs associated with LITT and ATL should be further investigated to better characterize the utility of LITT in temporal lobe epilepsy patients. [ABSTRACT FROM AUTHOR]

• LITT is difficult after craniectomy due to lack of bony surface to anchor the bolt. • A 3D-printed implant was used to enable LITT targeting of a posterior fossa lesion. • The customized plate had a built-in bolt trajectory that aligned with the tumor. • The customized plate was implemented under the FDA expanded access pathway. • This strategy enables use of LITT in patients who would not otherwise be candidates. Laser interstitial thermal therapy (LITT) is a minimally invasive neurosurgical technique that has been demonstrated to successfully ablate intracranial tumors. While LITT for supratentorial lesions can often be straightforward, ablation of infratentorial lesions can be difficult with current targeting technologies and instrumentation. The anatomical difficulty of targeting posterior fossa masses can be further complicated in patients who have had a prior craniectomy or other procedure that removed the bone that is required to set the surgical trajectory. This article describes use of a three-dimensional (3D)–printed customized surgical implant to improve and enable targeting of posterior fossa lesions using LITT, particularly in the setting of prior craniectomy. A 3D-printed implant was customized for a patient with a history of metastatic lung cancer and prior posterior fossa craniectomy who presented for treatment of a progressively enlarging contrast-enhancing lesion in the right cerebellar hemisphere. The device included a built-in bolt trajectory for LITT ablation. The temporary implant was successfully fabricated for use with laser ablation of a right cerebellar mass. Three potential trajectories for the LITT bolt were incorporated into the temporary implant, but only the primary trajectory was utilized. Laser ablation was performed with the implant and a SideFire laser probe. Customized 3D-printed implants can enable the use of LITT for patients who would not otherwise be candidates. [ABSTRACT FROM AUTHOR]

We describe our single-institutional experience with magnetic resonance−guided stereotactic laser ablation (SLA) for the treatment of newly diagnosed and recurrent pediatric brain tumors. Eighteen consecutive ablation procedures were performed in 17 patients from March 2016−April 2020. Patient demographics, indications, procedures, neuroimaging features, and outcomes were reviewed retrospectively. Seventeen patients (mean age of 11.4 years, 11 boys, 6 girls) underwent SLA with a mean follow-up of 24 months (range: 3–45 months). Tumor histologies included pilocytic astrocytoma (n = 5), ganglioglioma (n = 3), low-grade glioma not otherwise specified (n = 4), glioblastoma (n = 2), meningioma (n = 1), medulloblastoma (n = 1), and metastatic malignant peripheral nerve sheath tumor (n = 1). SLA was first-line therapy in 10 patients. Mean procedure duration including anesthesia time was 328 minutes (range: 244–529 minutes), and mean postoperative length of stay was 1.5 days (range 1–5 days). The complication rate was 29%, which included 3 patients who experienced postoperative motor changes, which resolved within several weeks of surgery, 1 patient with self-limited intraoperative bradycardia and hypotension, and 1 patient who died postoperatively due to intracranial hemorrhage from a distant lesion. Twelve of 17 patients had a neuroimaging response after SLA (4 complete responses, 8 partial responses, 1 stable disease). Percentage of tumor shrinkage from baseline ranged from 33%−100% (mean 75%). Patients with low-grade glioma exhibited the best responses to SLA (range 3%−100% decrease; mean 90%; 36% complete response rate). SLA is a minimally invasive modality for the treatment of newly diagnosed and recurrent low-grade pediatric brain tumors. Low-grade glioma exhibited the best responses. Identification of ideal candidates for SLA, mitigation of perioperative complications, and demonstration of long-term outcomes need to be better defined in a clinical trial setting. [ABSTRACT FROM AUTHOR]

Surgical resection has been shown to prolong survival in patients with glioblastoma multiforme (GBM), although this benefit has not been demonstrated for reoperation following tumor recurrence. Laser interstitial thermal therapy (LITT) is a minimally invasive ablation technique that has been shown to effectively reduce tumor burden in some patients with intracranial malignancy. The aim of this study was to describe the safety and efficacy of LITT for recurrent and newly diagnosed GBM at a large tertiary referral center. Patients with GBM receiving LITT were retrospectively analyzed. Overall survival from the time of LITT was the primary end point measured. There were 69 patients identified for inclusion in this study. The median age of the cohort was 56 years (range, 15–77 years). Median tumor volume was 10.4 cm3 (range, 1.0–64.0 cm3). A Kaplan-Meier estimate of median overall survival for the series from the time of LITT was 12 months (95% confidence interval 8–16 months). Median progression-free survival for the cohort from LITT was 4 months (95% confidence interval 3–7 months). Adjuvant chemotherapy significantly prolonged progression-free survival and overall survival (P < 0.01 for both) in the cohort. Gross total ablation was not significantly associated with progression-free survival (P = 0.09). LITT can safely reduce intracranial tumor burden in patients with GBM who have exhausted other adjuvant therapies or are poor candidates for conventional resection techniques. [ABSTRACT FROM AUTHOR]

To our knowledge, we report the first case of a cholangiocarcinoma brain metastasis successfully treated with magnetic resonance imaging (MRI)-guided laser interstitial thermal therapy. In 2017, a 71-year-old man was diagnosed with unresectable intrahepatic cholangiocarcinoma. In August 2018, a brain MRI scan was performed after a transient episode of altered mental status and revealed a subcentimeter enhancing lesion in the deep white matter of the right cerebellum. Due to lack of symptoms and the small size of the lesion, it was initially observed. However, a follow-up MRI scan at 2.5 months demonstrated increased lesion size with worsening perilesional edema. Given the rarity of cholangiocarcinoma brain metastases and the deep location, the patient underwent stereotactic needle biopsy to confirm the diagnosis followed by laser ablation as a primary treatment for the metastasis. The patient tolerated the surgery well with no complications, and the postoperative course was uneventful. At 16 months postablation, there has been no recurrence or disease progression. Although prognosis for these tumors is poor, our result suggests that laser ablation can be an effective treatment for this rare entity and is a representative example of the expanding indications for laser interstitial thermal therapy. [ABSTRACT FROM AUTHOR]

Treatment strategies for glioblastoma multiforme (GBM) of the corpus callosum have remained limited to stereotactic biopsy in many cases owing to the morbidity resulting from aggressive surgical resection. We performed a study of 3 patients with histologically proven GBM of the corpus callosum who had undergone bilateral laser interstitial thermal therapy (LITT). The data collected included demographics, tumor location and volume, tumor genetic markers, treatment volume, perioperative complications, and Karnofsky performance scale (KPS) score pre- and postoperatively. We performed 6 LITT sessions for the 3 patients with GBM of the corpus callosum. The mean patient age was 64 years, with an average tumor volume of 14.95 cm3. The mean pretreatment KPS score was 80, and no significant changes were found in the KPS scores at 1 month postoperatively. The mean extent of ablation was 98.6% on postoperative magnetic resonance imaging, and none of the patients had experienced perioperative complications. At 8 months of follow-up, 2 of the 3 patients were alive and neurologically stable compared with their preoperative state. The third patient had elected to defer radiotherapy and oncology treatment and was lost to follow-up. The mean progression-free survival was 3.55 months, with interval satellite lesions seen on follow-up imaging studies. Although our case series was small, we have demonstrated for the first time, to the best of our knowledge, that bilateral LITT is a safe and effective treatment of GBM of the corpus callosum. Given the known benefit of near gross total resection for high-grade glioma, we believe LITT might improve survival for these patients who otherwise would have undergone biopsy. [ABSTRACT FROM AUTHOR]

Stereotactic Radiosurgery has become the main treatment for patients with limited number of brain metastases (BM). Recently, with the increasing use of this modality, there is a growth in recurrence cases. Recurrence after radiation therapy can be divided in changes favoring either tumor recurrence or radiation necrosis (RN). Laser Interstitial Thermal Therapy (LITT) is minimally invasive treatment modality that has been used to treat primary and metastatic brain tumors. When associated with real-time thermometry using Magnetic Resonance Imaging, the extent of ablation can be controlled to provide maximum coverage and avoid eloquent areas. The objective of this study was to investigate the use of LITT in the treatment of BM. An extensive review of the relevant literature was conducted and the outcome results are discussed. There is an emphasis on safety and local control rate of patients treated with this modality. The findings of our study suggest that LITT is a viable safe technique to treat recurrent BM, especially in patients with deep-seated lesions where surgical resection is not an option. [ABSTRACT FROM AUTHOR]

Thermal coagulation is a central principle in surgery, particularly regarding hemostasis, as well as being an integral part of intracranial tumor removal. Traditionally, surgical hemostasis is achieved through application of unipolar or bipolar electrocautery. This method has been contemporized and specialized to treat intracranial tumors through a technique called stereotactic laser ablation (SLA), also known as laser interstitial thermal therapy. In this article, we present this technique as an additional option in the treatment of difficult intracranial tumors. Specifically, we report here a highly vascular and hemorrhagic pineocytoma found in a fragile, elderly patient who underwent a novel combination of procedures: SLA mediated devascularization followed by resection via an endoscopic approach. SLA-mediated thermal-coagulation is a potential strategy for minimizing hemorrhagic risks in brain tumor resection and may be used in conjunction with other approaches tailored to the patient and their disease. [ABSTRACT FROM AUTHOR]

Epilepsy with periventricular nodular heterotopia (PVNH) lacks a conclusive surgical treatment strategy as eloquent cortex and important white matter tracts frequently overlay the deep periventricular nodules. Our goal was to evaluate the safety and efficacy of laser interstitial thermal therapy (LITT) for the treatment of epilepsy in PVNH. Data on demographic characteristics, complications, visual outcomes, Engel classification at last follow-up, antiepileptic drug use, morbidity, and mortality among patients who underwent this procedure were retrospectively reviewed. Between May 2015 and January 2019, 5 patients underwent 6 LITT procedures for epilepsy with PVNH. One patient had residual nodules after their first procedure and underwent a second ablation. The average follow-up time was 12 months. Three patients were Engel class Ia, 1 patient was Engel class II, and 1 patient was Engel class III at last follow-up. Two patients were able to reduce their antiepileptic drugs postoperatively. Three patients had no changes in vision, 1 patient experienced a quadrantanopsia, and 1 patient had subjective blurry vision after their procedures. No patients experienced motor deficits, dysphasia, infection, or mortality. LITT appears to be a safe and promising option to provide seizure relief for patients with refractory epilepsy and PVNH that otherwise may not be surgical candidates. Some appropriately determined patients with refractory epilepsy may benefit from LITT before proceeding with an invasive intracranial evaluation. A larger sample size and long-term follow-up is necessary to further elucidate safety and efficacy. [ABSTRACT FROM AUTHOR]

Treatment for surgically inaccessible medically refractory cerebral radiation necrosis (RN) has remained limited. Recently, laser interstitial thermal therapy (LITT) has gained traction as an effective means of treating these lesions but limited data are available regarding the effect of ablation size on patient outcome. Therefore, this study analyzed various outcome measures as a function of ablation volume/diameter for a series of 20 patients with surgically inaccessible biopsy-proven RN. Twenty patients with biopsy-proven RN treated with LITT from 2013 to 2018 at our institution were retrospectively reviewed. Local progression-free survival (PFS), overall survival, and steroid dependence were analyzed with Kaplan-Meier and Cox regression analysis for ablation volume/diameter. Comparison of preoperative and postoperative Karnofsky Performance Status was conducted with a matched paired t test. Patients with subtotal ablation (<100% increase in pre-LITT lesion volume or <0 mm increase in pre-LITT lesion diameter) had higher risk of local disease progression (hazard ratio, 12.4; P = 0.004) compared with patients with total ablations. Patients who received radical ablations (>200% increase in pre-LITT lesion volume or >2 mm increase in pre-LITT lesion diameter) showed the most favorable PFS (P < 0.0458 and P < 0.0378, respectively). There was no difference in post-LITT Karnofsky Performance Status and time to steroid freedom between ablation groups. Overall survival increased with radical diametric ablation (P = 0.0401). Although LITT has proved to be an effective salvage therapy for patients with RN, detailed volumetric studies have not been explored. Our results suggest that radical ablations have the potential to increase PFS. [ABSTRACT FROM AUTHOR]

Laser interstitial thermal therapy (LITT) has been used for brain metastasis, epilepsy, and necrosis, as well as gliomas as a minimally invasive treatment for many years. With the improvement of the thermal monitoring and ablation precision, especially the application of magnetic resonance (MR) thermography in the procedure and the available two commercial laser systems nowadays, LITT is gradually accepted by more neurosurgical centers. Recently, some new concepts, for example the adjuvant chemotherapy or radiation following LITT, the combination of immunotherapy and LITT regarding the glioma treatment are proposed and currently being investigated. The aim of this study is to summarize the evolution of LITT especially for brain gliomas and a possible outlook of the future. [ABSTRACT FROM AUTHOR]

Magnetic resonance–guided laser interstitial thermal therapy is a minimally invasive procedure that uses intraoperative magnetic resonance thermometry (MRT) to generate a thermal damage estimate (TDE) of the ablative area. This study aimed to compare areas produced by the MRT heat map with the system-generated TDE produced by Visualase software. All ablations were performed using the Visualase laser ablation system. MRT heat map and TDE were quantified using MATLAB version R2014a. TDE was compared with the summed area of green, yellow, and red areas (heat map 63.9 [HM63.9]) and the summed area of light blue, green, yellow, and red areas (heat map 50.4 [HM50.4]) produced by the MRT heat map. Fifty-six patients undergoing magnetic resonance–guided laser interstitial thermal therapy were examined. Mean TDE produced was 236 mm2 (SEM = 9.5). Mean HM63.9 was 231 mm2 (SEM = 8.7), and mean HM50.4 was 370 mm2 (SEM = 12.8). There was no significant difference between TDE and HM63.9 (P = 0.51). There was a significant difference between TDE and HM50.4 (P < 0.001) and between HM63.9 and HM50.4 (P < 0.001). The system-generated TDE consistently remains contained within the boundaries of the MRT heat map. At standard factory settings, TDE and the area produced within the periphery of HM63.9 are similar in magnitude. The light blue portion of the MRT heat map may serve as an additional means of predicting when critical structures may be at risk during laser ablation if exposed to further thermal stress. [ABSTRACT FROM AUTHOR]

Posterior fossa tumors are rare in adults and pose a challenge to treat due to the bony contour of the posterior fossa, complex anatomical structures including deep venous sinuses, and the proximity of the fourth ventricle and brain stem. We describe our experience with laser interstitial thermal therapy (LITT) for the management of brain metastases and radiation necrosis of the posterior fossa. We retrospectively analyzed 13 patients with metastases and radiation necrosis of the posterior fossa managed with LITT. Thirteen patients with histopathologically confirmed radiation necrosis (n = 5) and metastases (n = 8) of the posterior fossa underwent LITT. The median preoperative tumor was 4.66 cm3, and median postoperative ablation cavity volume was 6.29 cm3. The median volume of the ablation cavity was decreased to 2.90 cm3 at a 9-month follow-up. The median volume of peritumoral edema was 12.25 cm3, which fell to a median of 5.77 cm3 at 1-month follow-up. The median progression-free survival was 7 months (range, 3–14 months) and the mean overall survival was 40 months (range, 2–49 months) after LITT. There were no intraoperative complications. One patient experienced palsy of the seventh and eighth cranial nerves on follow-up, attributable to LITT. Lesions of the posterior fossa are challenging to treat given their proximity to the dura and venous sinuses. Our findings demonstrate that LITT ablation may be a safe and feasible option for metastases and radiation necrosis of the posterior fossa. Larger studies are needed to confirm the efficacy of this approach. [ABSTRACT FROM AUTHOR]

The optimal treatment of brain metastases recurring after radiosurgery (BMRS) remains an area of active investigation. Stereotactic laser ablation (SLA, also known as laser interstitial thermal therapy) has recently emerged as a potential treatment option. To summarize the available literature on SLA as treatment of BMRS and synthesize findings on local control, overall survival, neurologic outcome, imaging findings, morbidity, and postprocedure clinical course. We performed a comprehensive search of PubMed for articles investigating SLA as treatment of BMRS. Thirteen peer-reviewed publications met our search criteria. Local control was a function of the percentage of tumor that was thermally ablated. In completely ablated tumors, 3-month local control was 80%–100%. Median survival ranged from 5.8 to 19.8 months. About two-thirds of treated lesions showed postablation expansion of contrast-enhancing volume and fluid-attenuated inversion recovery volume. Expansion could start within an hour of treatment, and resolution typically occurred within 6 months. Notably, maximal expanded contrast-enhancing volume could reach >3-fold the preoperative lesion volume. The incidence of SLA-related permanent neurologic injuries was <10%. The most common complications were hemorrhage, thermal injury causing neurologic deficit, and malignant cerebral edema. Nearly all patients were treated with dexamethasone, but there was variability in the dose and duration of therapy. Median hospital stay was 1–2 days (range, 1–5 days), and most treated patients were discharged home (range, 59.5%–100%). Our analysis provides support for continued development of SLA as a treatment of BMRS. Standardization of periprocedural management will be needed. [ABSTRACT FROM AUTHOR]

Clearpoint Smartframe is a magnetic resonance imaging−compatible stereotactic system often used to perform magnetic resonance imaging−guided biopsies. The system is typically mounted on the scalp through screws that pierce the skin and penetrate the outer table of the cranium. However, the frame can also be configured to be mounted directly onto the skull. Here, we describe the clinical context well suited for a skull-mount Clearpoint Smartframe surgery. The patient suffered from a subcentimeter right parafourth ventricular contrast-enhancing lesion with hydrocephalus and underwent a right suboccipital needle biopsy followed by an occipital ventriculoperitoneal shunt. Although the hydrocephalus resolved with the ventriculoperitoneal shunt, the biopsy sample proved nondiagnostic. The patient underwent a second procedure during which the Clearpoint Smartframe was mounted onto the skull through space dissected free during the previous surgery. Diagnostic biopsy (H3K27 glioma) was performed followed by stereotactic laser ablation of the lesion. We describe a case in which the skull mount Clearpoint Smartframe was used to biopsy and ablate a midline H3K27 glioma. [ABSTRACT FROM AUTHOR]

Laser interstitial thermal therapy (LITT) presents an important new minimally invasive tool in the management of drug-resistant mesial temporal epilepsy (MTE). However, because of its relative novelty, not much is known about long-term seizure freedom rates. The objective of this study was to evaluate the postsurgical seizure outcome following LITT after a minimum follow-up period of 2 years. Medical records of all patients who underwent LITT for MTE from 2013 to 2018 at our comprehensive epilepsy center under a single surgeon were retrospectively reviewed. Data related to demographics, presurgical evaluations, and seizure outcome were compared between seizure-free (SF) and non–seizure-free (NSF) patients. In all, 26 patients were identified with at least 2 years of follow-up. Mean age was 43.8 years ± 11.6 years, and 46.2% were female. After a mean follow-up time of 42.9 months (range, 24.3–58.8 months), 61.5% (16/26) were free of disabling seizures, and 26.9% (7/26) had only rare disabling seizures. Whereas seizure-freedom rates between patients with and without mesial temporal sclerosis (MTS) were not statistically different (68% vs. 43%, P = 0.23), NSF patients without MTS had a shorter median time to first seizure than did NSF patients with MTS (0.55 month vs. 10 months, log-rank test P = 0.007). Postoperative complications occurred in 2 patients (7.7%), consisting of 1 permanent and 1 transient homonymous hemianopia. LITT appears to be a safe and effective initial surgical option for treatment-resistant MTE. Among patients who have seizures after treatment, those without MTS appear to have seizures earlier than those with MTS. [ABSTRACT FROM AUTHOR]

Stereotactic laser ablation of mesial temporal structures is a promising new surgical intervention for patients with mesial temporal lobe epilepsy (MTLE). Since this procedure was first used to treat MTLE in 2010, the literature contains reports of 37 patients that underwent MR-guided stereotactic laser amygdalohippocampotomy (SLAH) using Laser Interstitial Thermal Therapy (LITT) with at least 1 year of follow-up. This early body of data suggests that SLAH is a safe and effective treatment for MTLE in properly selected patients. Moreover, SLAH is substantially less invasive when compared with open surgical procedures including standard anterior temporal lobectomy and its more selective variants, results in immediate destruction of tissue in contrast to radiosurgical treatments for MTLE, and can more readily ablate larger volumes of tissue than is possible with techniques employing radiofrequency ablation. Finally, evidence is accruing that SLAH is associated with lower overall risk of neuropsychological deficits compared to open surgery. Thus, LITT constitutes a novel minimally invasive tool in the neurosurgeon’s armamentarium for managing medically refractory seizures that may draw eligible patients to consider surgical interventions to manage their seizures. [ABSTRACT FROM AUTHOR]

Cognitive outcome data are reviewed with respect to the use of magnetic-resonance guided stereotactic laser ablation (SLA) as an epilepsy surgical procedure, with comparisons drawn to traditional open resection procedures. Cognitive outcome with stereotactic laser amygdalohippocampotomy (SLAH) appears better than open resection for several functions dependent on extra-mesial temporal lobe (TL) structures, including category-related naming, verbal fluency, and object/familiar person recognition. Preliminary data suggests episodic, declarative verbal memory can decline following SLAH in the language dominant hemisphere, although early findings suggest comparable or even superior outcomes compared with open resection. The hippocampus has long been considered a central structure supporting episodic, declarative memory, with epilepsy surgical teams attempting to spare it whenever possible. However, ample data from animal and human neuroscience research suggests declarative memory deficits are greater following broader mesial TL lesions that include parahippocampal gyrus and lateral TL inputs. Therefore, employing a neurosurgical technique that restricts the surgical lesion zone holds promise for achieving a better cognitive outcome. Focal SLA lesions outside of the amygdalohippocampal complex may impair select cognitive functions, although few data have been published in such patients to date. SLA is being effectively employed with adults and children with TL or lesional epilepsies across several U.S. epilepsy centers, which may simultaneously optimize cognitive outcome while providing a curative treatment for seizures. [ABSTRACT FROM AUTHOR]

Surgery is the most effective treatment for drug-resistant epilepsy. Long-term studies demonstrate that about 60% to 80% of patients become seizure-free after anterior temporal lobectomy and a majority of patients (about 95%) report significant seizure reduction after surgery. In the last few years, there has been significant advances in minimally invasive surgical techniques to treat drug-resistant epilepsy. These minimally invasive procedures have significant advantages over open surgery in that they produce less immediate discomfort and disability, while allowing for greater preservation of functional tissue. Laser interstitial thermal therapy (LiTT) is an example of such a procedure. Recent advances in imaging, surgical navigation, and real-time thermal monitoring have made LiTT safer and easier to implement, offering an effective and powerful neurosurgical tool for drug-resistant epilepsy. This article will review the technical considerations, uses, and potential future directions for LiTT in drug-resistant epilepsy. [ABSTRACT FROM AUTHOR]

Pre-operative scalp shaving is conventionally thought to simplify postoperative cranial wound care, lower the rate of wound infections, and ease optimal incision localization. Over the past few decades, some neurosurgeons have refrained from scalp shaving in order to improve patient satisfaction with brain surgery. However, this hair-sparing approach has not yet been explored in the growing field of magnetic resonance-guided laser interstitial thermal therapy (MRgLITT). This study investigated the initial impact of a no-shave technique on post-operative wound infection rate as well as on entry and target accuracy in MRgLITT for mesial temporal epilepsy. Eighteen patients selected by the Stanford Comprehensive Epilepsy Program between November 2015 and August 2017 were included in the study. All patients underwent functional selective amygdalohippocampotomies using MRgLITT entirely within a diagnostic MRI suite. No hair was removed and no additional precautions were taken for hair or scalp care. Otherwise, routine protocols for surgical preparations and wound closure were followed. The study was performed under approval from Stanford University’s Internal Review Board (IRB-37830). No post-operative wound infections or erosions occurred for any patient. The mean entry point error was 2.87 ± 1.3 mm and the mean target error was 1.0 ± 0.9 mm. There have been no other complications associated with this hair-sparing approach. The study’s results suggest that hair sparing in MRgLITT surgery for temporal epilepsy does not increase the risk of wound complications or compromise accuracy. This preferred cosmetic approach may thus appeal to epilepsy patients considering such interventions. [ABSTRACT FROM AUTHOR]

New treatment approaches in epilepsy – such as novel antiepileptic drugs and neurostimulation – generally at first are assessed in animal models in regard to feasibility, efficacy and safety. The aim of this review was to elucidate and summarize the available literature on in vivo experimental studies on radiofrequency thermoablation and laser interstitial thermal therapy. We have found two in vivo studies on radiofrequency ablation of an acute seizure focus, one assessed the conventional transcranial and the other one a transvenous approach. All other studies focused on technical issues of functional ablation of brain structures assessing parameters such as maximal temperature and duration of thermal ablation as well as electrode devices. As the concept of functional ablation is evident – destruction of the epileptogenic focus as performed in “open” resective surgery – general “proof of concept” experiments do not seem to be necessary. [ABSTRACT FROM AUTHOR]

Cerebral cavernous malformations (CCM) in deep eloquent areas present a surgical challenge. Laser interstitial thermal therapy (LITT) may present itself as a safe minimally invasive treatment option. To systematically review the indications, safety, and outcomes of LITT for CCM. Electronic databases were searched from inception to October 7, 2021 for articles with CCM and LITT keywords. Studies describing CCMs treated with LITT were included. A total of 32 patients with CCMs in lobar (79%), basal ganglia (12%), and brainstem (9%) locations were treated with LITT. Indications for LITT included drug-resistant seizures (75%), unacceptable surgical risk (22%), recurrent hemorrhage (16%), and early intervention to discontinue antiepileptic drugs (3%). No death or CCM-associated intracranial hemorrhage occurred intraoperatively or postoperatively, and most patients experienced no adverse effects or transient effects that resolved at follow-up (84%). Of those treated for CCM-associated epilepsy, 83% experienced Engel class I seizure freedom and most were class IA (61%). Most patients experienced symptomatic improvement (93%), and a decrease in antiepileptic drugs was reported in more than half of patients (56%), with 28% able to discontinue all antiepilepsy medications after LITT. LITT seems to be a safe treatment for CCMs located in deep eloquent areas and in lesions presenting with medically refractory seizures or recurrent hemorrhages. Randomized studies are needed to further elucidate its efficacy in treating CCM. [ABSTRACT FROM AUTHOR]

Laser interstitial thermal therapy (LITT) is a new therapeutic strategy being explored in prostate cancer (CaP), which involves focal ablation of organ-localized tumor via an interstitial laser fiber. While little is known about treatment-related changes following LITT, studying post-LITT changes via imaging is extremely significant for enabling early image-guided intervention and follow-up. In this work, we present the first attempt at examining focal treatment-related changes on a per-voxel basis via quantitative comparison of MRI features pre- and post-LITT, and hence identifying computerized MRI features that are highly sensitive as well as specific to post-LITT changes within the ablation zone in the prostate. A retrospective cohort of 5 patient datasets comprising both pre- and post-LITT T2-weighted (T2w) and diffusion-weighted (DWI) acquisitions was considered, where DWI MRI yielded an Apparent Diffusion Co-efficient (ADC) map. Our scheme involved (1) inter-protocol registration of T2w and ADC MRI, as well as inter-acquisition registration of pre- and post-LITT MRI, (2) quantitation of MRI parameters by correcting for intensity drift in order to examine tissue-specific response, and (3) quantification of the information captured by T2w MRI and ADC maps via texture and intensity features. Correction of parameter drift resulted in visually discernible improvements in highlighting tissue-specific response in different MRI features. Quantitative, voxel-wise comparison of the changes in different MRI features indicated that steerable and non-steerable gradient texture features, rather than the original T2w intensity and ADC values, were highly sensitive as well as specific in identifying changes within the ablation zone pre- and post-LITT. The highest ranked texture feature yielded a normalized percentage change of 186% within the ablation zone and 43% in a spatially distinct normal region, relative to its pre-LITT value. By comparison, both the original T2w intensity and the ADC value demonstrated a markedly less sensitive and specific response to changes within the ablation zone. Qualitative as well as quantitative evaluation of co-occurrence texture features indicated the presence of LITT-related effects such as edema adjacent to the ablation zone, which were indiscernible on the original T2w and ADC images. Our preliminary results thus indicate great potential for non-invasive computerized MRI imaging features for determining focal treatment related changes, informing image-guided interventions, as well as predicting long- and short-term patient outcome. [ABSTRACT FROM AUTHOR]

During the laser and ultrasound based thermotherapy it is always desirable to have a precise necrosis of deeply seated tumor preserving the adjoining healthy tissue with minimum thermally induced nociceptive pain sensation to the patient. The aim of the present study is to compare the thermomechanical response of vascular tissues with and without nanoparticles between (a) continuous and pulse mode heating, and (b) focused ultrasound and interstitial laser heating. A 3-D multi-layered and multi-leveled vascular breast tumor model was developed. The present bioheat model incorporates inhomogeneous tissue conditions in the form of non-Fourier time lagging characteristics and complex vascular network of tissue. The radiative transfer, linearized pressure wave, momentum, dual-phase-lag, Arrhenius, and equilibrium equations were solved for the optic, acoustic, fluid, temperature, damage and mechanical fields respectively using the COMSOL Multiphysics (Bangalore, India) software. An in-vitro study on agar based tissue phantom was also performed to validate the present numerical results of focused ultrasound heating. The non-Fourier effect on temperature and damage responses of tissue has been revealed more in focused ultrasound based continuous mode heating compared to the interstitial laser based pulse mode heating. With limited tissue temperature rise, the proposed pulse mode heating scheme provides tumor specific ablation sparing the healthy tissues with minimum thermally induced nociceptive pain unlike the continuous mode heating scheme. Further, the presence of nanoparticles and multilevel artery and vein in present tumor model causes significant changes in thermal, damage, and mechanical responses under external heating. The present findings could be beneficial in understanding the role of different heat imposition techniques during the nanoparticle assisted minimally invasive thermo-therapy of cancer. • A computational study on thermo-mechanical response of nanoparticle mixed tissue under ultrasound and laser heating. • Targeted tumor ablation with minimum induced nociceptive pain considering pulsed excitation with lower duty cycle (16.6%). • Dual Phase lag Bioheat model in multi-level vasculature tissue structure signifying inhomogeneous tissue condition. • An in-vitro thermal study on agar based tissue phantom under focused ultrasound heating in presence of gold nanospheres. [ABSTRACT FROM AUTHOR]

Background The application of laser interstitial thermal therapy (LITT) for intracranial lesions in the posterior fossa tumors remains challenging due to the smaller size of this compartment as well as the thickness and angle of the occipital bone. In this study, we reviewed our experience with this treatment modality for posterior fossa lesions. Methods We retrospectively reviewed our series of 8 patients with posterior fossa tumors treated with LITT from an Institutional Review Board–approved brain tumor database (2012–2017) of more than 200 cases at our institution. Results The 8 patients underwent LITT targeting 3 metastases, 2 pilocytic astrocytomas, 2 zones of radiation necrosis after radiosurgery, and 1 glioblastoma (GBM). The mean preoperative lesion volume was 4.35 cm 3 . A 6 months postsurgery, the mean lesion volume had decreased from 9.64 cm 3 to 5.72 cm 3 . Two of the tumors (the GBM and a metastatic adenocarcinoma) progressed after 8.5 and 7.5 months, respectively, with mortality after 1.1 and 1.6 years, respectively. Surgical resection was performed in a patient with metastatic adenocarcinoma tumor at 7.7 months after LITT. All other lesions remained stable or were diminished at a median follow-up of 14.8 months (range, 0.4–37.5 months). Magnetic resonance imaging (MRI) on the first postoperative day, showed an increase in mean tumor-related edema volume from 9.45 cm 3 to 14.10 cm 3 . After a postoperative follow-up of at least 1 month, this mean decreased to 8.70 cm 3 . One case each of transient partial unilateral sixth cranial nerve palsy, superficial wound infection, and a late obstructive hydrocephalus were noted postoperatively. No mortality was associated with the procedure. Conclusions LITT is a safe and feasible treatment modality even in challenging locations like the posterior fossa. However, surgical indications should be tailored for each individual patient based on the size and location of tumor. [ABSTRACT FROM AUTHOR]

Background A stereotactically placed laser fiber can deliver thermal energy to an epileptogenic focus in the brain. This procedure is done under intraoperative (thermography) magnetic resonance imaging (MRI) guidance. Thermoablation can lead to edema in the surrounding area and can cause a secondary insult. In this report of 3 cases, we have quantified the edema produced after laser ablation by sequential MRI in the immediate postoperative period. Case Descriptions Three patients with intractable epilepsy underwent a detailed neurologic and neuroradiologic workup to localize the site of epileptogenic foci. Two of the patients had mesial temporal lobe sclerosis, and the other patient had hypothalamic hamartoma. A laser fiber was placed stereotactically in the epileptogenic zone, and MRI-guided thermoablation was done. Postoperatively, T1-weighted and fluid-attenuated inversion recovery (FLAIR)-based volumetric MRI sequences were performed on postoperative days 1, 3, and 5 to quantify the edema. I-Plan software was used for volumetric analysis. Targeted volumes were 0.22, 4.2, and 3.5 mL, and lesions were 0.3, 6.5, and 6 mL, respectively. FLAIR hyperintensity was 2.3, 11.8, and 8.4 mL on the first postoperative day and 1.5, 12.6, and 6.3 mL on postoperative day 8. All patients remained seizure-free during the postoperative period. No complications were observed. Conclusions Laser ablation of epileptic focus is safe. FLAIR hyperintensity in the postoperative period is 3–5 times the targeted volume. However, no significant increase occurs during the first 8 days, and thus steroids can be stopped within 5 days of surgery. [ABSTRACT FROM AUTHOR]