Laser interstitial thermal therapy: A first line treatment for seizures due to hypothalamic hamartoma?

MR-guided laser interstitial thermal therapy in the treatment of brain tumors and epilepsy

MR-guided Laser Interstitial Thermal Therapy (MRgLITT) is a minimally invasive neurosurgical technique increasingly used for the treatment of drug-resistant epilepsy and brain tumors. Utilizing near-infrared light energy delivery guided by real-time MRI thermometry, MRgLITT enables precise ablation of targeted brain tissues, resulting in limited corridor-related morbidity and expedited postoperative recovery. Since receiving CE marking in 2018, the adoption of MRgLITT has expanded to more than 40 neurosurgical centers across Europe. In epilepsy treatment, MRgLITT can be applied to various types of focal lesional epilepsy, including mesial temporal lobe epilepsy, hypothalamic hamartoma, focal cortical dysplasias, periventricular heterotopias, cavernous malformations, dysembryoplastic neuroepithelial tumors (DNET), low-grade gliomas, tuberous sclerosis, and in disconnective surgeries. In neuro-oncology, MRgLITT is used for treating newly diagnosed and recurrent primary brain tumors, brain metastases, and radiation necrosis. This comprehensive review presents an overview of the current evidence and technical considerations for the use of MRgLITT in treating various pathologies associated with drug-resistant epilepsy and brain tumors.

Magnetic Resonance-Guided Laser Interstitial Thermal Therapy in the Management of Hypothalamic Hamartomas: A Systematic Review and Meta-Analysis

OBJECTIVE

Magnetic resonance-guided laser interstitial thermal therapy (MRg-LITT) is a promising new technique to ablate epileptic foci in patients with hypothalamic hamartoma (HH). We aim to systematically synthesize all available evidence and determine the effectiveness of MRg-LITT in reducing seizures in patients with HH.

METHODS

We systematically searched MEDLINE (PubMed), Embase (Ovid), Scopus, and Google Scholar for all relevant articles. We used Open[Meta]Analyst to pool the number of seizure-free patients after MRg-LITT treatment in a random-effects model. Risk ratios were calculated, and subgroups were analyzed. Comprehensive meta-analysis was used to assess publication bias via funnel plots, Egger's regression test, and Begg's correlation test. This review complies with the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines.

RESULTS

After screening the titles, abstracts, and full texts, we included 17 articles in our meta-analysis, which revealed a 77.1% rate of seizure freedom (95% confidence interval 0.696-0.837, P<0.001), with moderate heterogeneity (I2=49.46%). Subgroup analysis by study design and sensitivity analyses excluding 1 study at a time did not impact the results substantially, and we found no evidence of publication bias. Adverse effects included electrolyte imbalances, weight gain, and transient neurologic disturbances.

CONCLUSIONS

MRg-LITT might be a feasible and effective technique for ablation of epileptic foci, leading to seizure freedom in a large proportion of patients with HH. However, there is a paucity of literature on the topic, and prospective clinical trials with larger number of participants comparing MRg-LITT to open surgery are needed.

Hypothalamic Hamartoma related epilepsy: A systematic review exploring clinical, neuropsychological, and psychiatric outcome after surgery

The post-surgical outcome for Hypothalamic Hamartoma (HH) related epilepsy in terms of seizure freedom (SF) has been extensively studied, while cognitive and psychiatric outcome has been less frequently reported and defined. This is a systematic review of English language papers, analyzing the post-surgical outcome in series of patients with HH-related epilepsy (≥5 patients, at least 6 months follow-up), published within January 2002-December 2022. SF was measured using Engel scale/equivalent scales. We looked at the outcome related to different surgical techniques, and HH types according to Delalande classification. We evaluated the neuropsychological and neuropsychiatric status after surgery, and the occurrence of post-surgical complications. Forty-six articles reporting 1318 patients were included, of which ten pediatric series. SF was reported in 686/1222 patients (56,1%). Delalande classification was reported in 663 patients from 24 studies, of which 70 were type I HH (10%), 320 were type II HH (48%), 189 were type III HH (29%) and 84 were type IV HH (13%). The outcome in term of SF was reported in 243 out of 663 patients. SF was reported in 12 of 24 type I HH (50%), 80 of 132 type II HH (60,6%), 32 of 59 type III HH (54,2%) and 12 of 28 type IV HH (42,9%). SF was reached in 129/262 (49,2%) after microsurgery, 102/199 (51,3%) after endoscopic surgery, 46/114 (40,6%) after gamma knife surgery, 245/353 (69,4%) after radiofrequency thermocoagulation, and 107/152 (70,4%) after MRI-guided laser interstitial thermal therapy. Hyperphagia/weight gain were the most reported surgical complications. Others were electrolyte alterations, diabetes insipidus, hypotiroidism, transient hyperthermia/poikilothermia. The highest percentage of memory deficits was reported after microsurgery, while hemiparesis and cranial nerves palsy were reported after microsurgery or endoscopic surgery. Thirty studies reported developmental delay/intellectual disability in 424/819 (51,7%) patients. 248/346 patients obtained a global improvement (72%), 70/346 were stable (20%), 28/346 got worse (8%). 22 studies reported psychiatric disorders in 257/465 patients (55,3%). 78/98 patients improved (80%), 13/98 remained stable (13%), 7/98 got worse (7%). Most of the patients had non-structured cognitive/psychiatric assessments. Based on the available data, the surgical management in patients with HH related epilepsy should be individualized, aiming to reach not only the best epilepsy result, but also the optimal cognitive and psychiatric outcome.

Gamma Knife Radiosurgery for Hypothalamic Hamartoma: A Multi-Institutional Retrospective Study on Safety, Efficacy, and Complication Profile

BACKGROUND AND OBJECTIVES

Gamma knife radiosurgery (GKRS) is a safe and effective treatment option for hypothalamic hamartomas (HH), but there is no consensus opinion on its timing, dosage, and follow-up. The aim of this study was to define the safety, efficacy, outcome, and complication profile of GKRS in this patient population.

METHODS

This retrospective multicentric study involved 39 patients with the mean age of 16 ± 14.84 years. Early seizures resulted in an earlier age of diagnosis in 97% of patients. At baseline, no endocrine abnormalities were seen in 75% of patients while 18.9% showed precocious puberty (PP). The median target volume was 0.55 cc (0.1-10.00 cc), and a median margin dose of 16 Gy (8.1-20.0 Gy) was delivered in a single session. All patients were evaluated for clinical, endocrinological, and radiological outcomes.

RESULTS

The median follow-up was 5 (0.1-15) years. The median target volume of the cohort was 0.55 (0.35-1.77) cc. The largest HH was of 10 cc. 24/39 (61.5%) were small HH (Regis I-III). At presentation, 94.8% patients suffered from seizures (87.18% with gelastic seizures). 7/39 patients (17.9%) were presented with both PP and epilepsy. Only one (2.6%) patient presented with PP alone. 29 patients had more than 3-year follow-up. All received ≥16 Gy targeting complete HH. 28% of patients showed regression in HH volume. Patients with Regis grade I-III and longer follow-up (>75 months) showed gradual improvement in seizures. 16/29 patients (55.2%) achieved good seizure control (Engel I/II) while 13 (44.8%) were in Engel III/IV status. Nine patients needed adjuvant treatment because of poor seizure control. Eight patients suffered from transient increase in seizures. One patient developed poikilothermia, and 2 patients developed new onset hormonal deficiency.

CONCLUSION

GKRS is a safe and effective modality for treatment of HH with significant improvement in seizure control with minimal disruption of endocrine profile. It provides an excellent safety, efficacy, and complication profile, especially for small HH. Latency of results and its adjuvant nature remain the areas of research and breakthroughs among contemporary treatment options.

Temporo-Parieto-Occipital Disconnection by Robot-Assisted Magnetic Resonance Imaging-Guided Laser Interstitial Thermal Therapy for Refractory Epilepsy in a Pediatric Patient: Proof-of-Principle Case Report and Surgical Nuances

OBJECTIVE

Magnetic resonance imaging-guided laser interstitial thermal therapy (MRIgLITT) has been proven safe and effective for the treatment of focal epilepsy of different etiologies. It has also been used to disconnect brain tissue in more extensive or diffuse epilepsy, such as corpus callosotomy and hemispherotomy.

METHODS

In this study, we report a case of temporo-parieto-occipital disconnection surgery performed using MRIgLITT assisted by a robotic arm for refractory epilepsy of the posterior quadrant. A highly realistic cadaver simulation was performed before the actual surgery.

RESULTS

The patient was a 14-year-old boy whose seizures began at the age of 8. The epilepsy was a result of a left perinatal ischemic event that caused a porencephalic cyst, and despite receiving multiple antiepileptic drugs, the patient continued to experience daily seizures which led to the recommendation of surgery.

CONCLUSIONS

A Wada test lateralized language in the right hemisphere. Motor and sensory function was confirmed in the left hemisphere through magnetic resonance imaging functional studies and NexStim. The left MRIgLITT temporo-parieto-occipital disconnection disconnection was achieved using 5 laser fibers. The patient followed an excellent postoperative course and was seizure-free, with no additional neurological deficits 24 months after the surgery.

Direct resection is a safe and effective strategy to control seizures in patients with hypothalamic hamartoma

Achieving favorable seizure outcomes is challenging in patients with seizures resulting from hypothalamic hamartoma. Although minimally invasive and non-invasive surgical procedures are used to treat this population, these procedures have limitations. Therefore, we analyzed the outcomes of patients with hypothalamic hamartoma following direct resection. We included 159 patients with hypothalamic hamartoma who underwent direct resection using the transcallosal interforniceal approach between 2011 and 2018. The relationships between clinical parameters and seizure outcomes were analyzed. In total, 55.3% achieved gross total resection and 25.2% underwent near-total resection. Of all patients, 79.2% were overall seizure-free at one year, but this number dropped to 77.0% at more than five years. Moreover, 88.4% (129/146) reached gelastic seizure (GS)-free status at one year and this number increased to 89.0% (97/109) at more than five years. Seventy-one patients took antiseizure medication (ASM) long-term, 68 took it for one year, and 11 took it for one-half year. The duration of ASM consumption (p < 0.001) and extent of hypothalamic hamartoma resection (p = 0.016) were significant independent predictors of long-term overall seizure-free survival, while the duration of ASM consumption (p = 0.011) and extent of hypothalamic hamartoma resection (p = 0.026) were significant independent predictors of long-term GS-free survival. Most patients' behavior, school performance, and intelligence were not affected after surgery. Direct resection is effective and safe strategy for patients with hypothalamic hamartomas. Hypothalamic hamartomas should be removed as completely as possible, and patients should take ASM long-term following surgery to reach long-term overall seizure-free or GS-free status.

Epileptic encephalopathies secondary to hypothalamic hamartomas treated with radiosurgery: A case series

OBJECTIVE

Hypothalamic hamartomas are congenital lesions that typically present with gelastic seizures, refractory epilepsy, neurodevelopmental delay, and severe cognitive impairment. Surgical procedures have been reported to be effective in removing the hamartomas, however, they are associated with significant morbidity. Therefore, it is not considered a safe therapeutic modality. Image-guided robotic radiosurgery (CyberKnife® Radiosurgery System) has been shown to provide good outcomes without lasting complications.

METHODS

This series of cases describes the clinical, radiological, radiotherapeutic, and postsurgical outcomes of five patients with epileptic encephalopathies secondary to hypothalamic hamartomas who were treated with CyberKnife®.

RESULTS

All patients exhibited refractory epilepsy with gelastic seizures and were unsuitable candidates for surgical resection The prescribed dose ranged between 16 and 25 Gy, delivered in a single fraction for four patients and five fractions for one patient while adhering strictly to visual pathway constraints. After radiosurgery, four patients maintained seizure control (one with an Engel class Ia, three with an Engel class 1d), and another presented sporadic, nondisabling gelastic seizures (with an Engel class IIa). After 24-26 months of follow-up, in three patients, their intelligence quotient scores increased. No complications were reported.

SIGNIFICANCE

This report suggests that Cyberknife may be a good option for treating hypothalamic hamartoma, particularly in cases where other noninvasive alternatives are unavailable. Nevertheless, additional studies are essential in order to evaluate the effectiveness of the technique in these cases.

[Hypothalamic hamartoma dissection using focused ultrasound under MRI control. The first successful experience in Russia]

Treatment of motor disorders by MRI-guided focused ultrasound is an alternative to neuro- and radiosurgery such as stereotactic radiofrequency ablation and thalamotomy with a gamma knife. However, safety, efficacy and feasibility of this technology for intracranial neoplasms are still unclear. The authors report successful hypothalamic hamartoma dissection by MRI-guided focused ultrasound in a 32-year-old woman with drug-resistant gelastic epilepsy and violent laughter and crying attacks. Magnetic resonance imaging revealed type II hypothalamic hamartoma. The last one was detached from surrounding brain tissue by MRI-guided focused ultrasound without side effects. Symptoms regressed immediately after surgery. No laughter and crying attacks were observed throughout 6-month follow-up.

Seizure outcomes and safety profiles of surgical options for epilepsy associated to hypothalamic hamartomas. A systematic review and meta-analysis

PURPOSE

Several surgical options are available for treating hypothalamic hamartoma-related epilepsy but their respective efficacy and safety profiles are poorly defined.

METHODS

A literature search identified English-language articles reporting series of patients (minimum 3 patients with a follow-up ≥12 months) operated on by either microsurgery, endoscopic surgery, radiosurgery, radiofrequency thermocoagulation or laser interstitial thermal therapy for hypothalamic hamartoma-related epilepsy. The unit of analysis was each selected study. Pooled rates of seizure freedom and of neurological and endocrinological complications were analyzed using meta-analysis to calculate both fixed and random effects. The results of meta-analyses were compared.

RESULTS

Thirty-nine studies were included. There were 568 and 514 participants for seizure outcome and complication analyses, respectively. The pairwise comparison showed that: i) the proportion of seizure-free cases was significantly lower for radiosurgery as compared to microsurgery, radiofrequency thermocoagulation and laser ablation, and significantly lower for endoscopic surgery as compared to radiofrequency thermocoagulation; ii) the proportion of permanent hypothalamic dysfunction was significantly higher for microsurgery as compared to all other techniques, and significantly lower for endoscopic surgery as compared to radiofrequency thermocoagulation and laser ablation; iii) the incidence of permanent neurological disorders was significantly higher for microsurgery as compared to endoscopic surgery, radiosurgery and radiofrequency thermocoagulation, and significantly lower for radiosurgery as compared to laser ablation.

CONCLUSIONS

Minimally invasive surgical techniques, including endoscopic surgery, radiofrequency thermocoagulation and laser ablation, represent an acceptable compromise between efficacy and safety in the treatment of hypothalamic hamartoma-related epilepsy. Microsurgery and radiosurgery should be considered in carefully selected cases.

Frameless robot-assisted stereoelectroencephalography-guided radiofrequency: methodology, results, complications and stereotactic application accuracy in pediatric hypothalamic hamartomas

Objective

We aimed to investigate the methodology, results, complications and stereotactic application accuracy of electrode implantation and its explanatory variables in stereoelectroencephalography-guided radiofrequency thermocoagulation (SEEG-RFTC) for pediatric hypothalamic hamartoma.

Methods

Children with hypothalamic hamartoma who underwent robot-assisted SEEG-RFTC between December 2017 and November 2021 were retrospectively analyzed. The methodology, seizure outcome, complications, in vivo accuracy of electrode implantation and its explanatory variables were analyzed.

Results

A total of 161 electrodes were implanted in 28 patients with 30 surgeries. Nine electrodes not following the planned trajectories due to intraoperative replanning were excluded, and the entry point and target point errors of 152 electrodes were statistically analyzed. The median entry point error was 0.87 mm (interquartile range, 0.50-1.41 mm), and the median target point error was 2.74 mm (interquartile range, 2.01-3.63 mm). Multifactor analysis showed that whether the electrode was bent (b = 2.16, p < 0.001), the length of the intracranial electrode (b = 0.02, p = 0.049), and the entry point error (b = 0.337, p = 0.017) had statistically significant effects on the target error. During follow-up (mean duration 31 months), 27 of 30 (90%) procedures were seizure-free. The implantation-related complication rate was 2.6% (4/152), and the major complication rate in all procedures was 6.7% (2/30).

Conclusion

Robot-assisted SEEG-RFTC is a safe, effective and accurate procedure for pediatric hypothalamic hamartoma. Explanatory variables significantly associated with the target point localization error at multivariate analysis include whether the intracranial electrode is bent, the intracranial electrode length and the entry point error.

Epilepsy surgery in patients with hypothalamic hamartomas - Population-based two-year and long-term outcomes

OBJECTIVE

Hypothalamic hamartomas are benign lesions associated with drug resistant epilepsy. Surgical treatment has become an increasingly utilised approach with promising results. This study aims to evaluate seizure outcome and complications after surgery in a population-based series of patients with intractable epilepsy and hypothalamic hamartoma.

METHODS

All patients with hypothalamic hamartoma treated with epilepsy surgery in Sweden since 1995 with at least two years of follow-up were included. Preoperative, two-, five- and ten-year prospective longitudinal data were collected from The Swedish National Epilepsy Surgery Register. Data included seizure types and frequency, duration of epilepsy, clinical characteristics, neurological deficits, cognitive level and complications. In a subgroup from Gothenburg, we also analysed data not included in the register such as classification of hamartomas, surgical procedures and gelastic seizures.

RESULTS

Eighteen patients were operated on during the period 1995-2020. The median age at epilepsy onset was 6 months and age at surgery 13 years. Four were seizure free and another four had ≥75% reduction in seizure frequency at the two-year follow-up. Two of the 13 patients with a long-term follow-up (five or ten years) were seizure-free and four had ≥75% reduction in seizure frequency. Three had an increased seizure frequency. No major complications were seen. Five had minor complications. In the Gothenburg subgroup all had open pterional disconnection or intraventricular endoscopic disconnection. Six of 12 were free from gelastic seizures at the two-year follow-up and six of eight at the long-term follow-up.

CONCLUSION

This study supports surgical treatment of hypothalamic hamartomas as a safe method with a low risk of permanent complications. The seizure reduction seems to be persistent over time.

Protocol of a prospective multicenter randomized controlled trial of robot-assisted stereotactic lesioning in the treatment of focal drug-resistant epilepsy

BACKGROUND

This protocol describes the design of a multicenter randomized controlled trial of robot-assisted stereotactic lesioning versus epileptogenic foci resection. Typical causes of focal epilepsy include hippocampal sclerosis and focal cortical dysplasia. These patients usually present with drug resistance and require surgical treatment. Although epileptogenic foci resection is still the most commonly used treatment for such focal epilepsy, there is increasing evidence that epileptogenic focus resection may lead to neurological impairment. The treatment of epilepsy with a robot-assisted stereotactic lesioning mainly includes two new minimally invasive surgical methods: radiofrequency thermocoagulation (RF-TC) and laser interstitial thermal therapy (LITT). Seizure-free is less likely to be achieved by these two procedures, but neurologic preservation is better. In this study, we aimed to compare the safety and efficacy of RF-TC, LITT, and epileptogenic foci resection for focal drug-resistant epilepsy.

METHODS

This is a multicenter, three-arm, randomized controlled clinical trial. The study will include patients older than 3 years of age with epilepsy who have had medically refractory seizures for at least 2 years and are eligible for surgical treatment with an epileptogenic focus as determined by multidisciplinary evaluation prior to randomization. The primary outcome measure is seizure outcome (quantified by seizure remission rate) at 3-month, 6-month, and 1-year follow-up after treatment. Postoperative neurologic impairment, spectrum distribution change of video electroencephalogram, quality of life, and medical costs will also be assessed as secondary outcomes.

TRIAL REGISTRATION

Chinese Clinical Trials Registry ChiCTR2200060974. Registered on June 14, 2022. The status of the trial is recruiting, and the estimated study completion date is December 31, 2024.

Advances in hypothalamic hamartoma research over the past 30 years (1992-2021): a bibliometric analysis

Background

Hypothalamic hamartoma (HH) is a rare intracranial disease whose manifestations include gelastic seizures and precocious puberty. The diagnosis and treatment of HH have changed substantially over the past three decades as medical care has improved. Bibliometrics can reveal the evolution and development of a scientific field.

Methods

Documents on HH were retrieved from the Web of Science Core Collection (WoSCC) database on September 8, 2022. The search terms were as follows: "hypothalamic hamartoma" or "hamartoma of the hypothalamus" or "hypothalamic hamartomas." The types of documents were restricted to articles, case reports, and reviews. VOSviewer, CiteSpace, and the R package "bibliometrix" were used for a bibliometric analysis.

Results

A total of 667 independent documents on HH were obtained from the WoSCC database. The most common types of documents were articles (n = 498, 75%) and reviews (n = 103, 15%). The number of annual publications fluctuated but showed an upward trend overall, and the annual growth rate was 6.85%. The cumulative publication data indicated that the most influential journals in the HH field include Epilepsia, Epileptic Disorders, Child's Nervous System, Neurosurgery, and the Journal of Neurosurgery. Kerrigan JF, Ng YT, Rekate HL, Regis J, and Kameyama S were among the most prominent authors in the field of HH, with numerous publications and citations. American research institutions, especially the Barrow Neurological Institute, occupied a pivotal position in HH research. Other countries and institutions were catching up and producing considerable research results. Research on HH has steadily switched its emphasis from Pallister-Hall syndrome (PHS) and precocious puberty to epilepsy and new diagnostic and therapeutic techniques, including Gamma Knife, laser ablation, and interstitial thermal therapy.

Conclusion

HH remains a special neurological disease with significant research prospects. The development of novel technologies, including MRI-guided laser-induced thermal therapy (MRg-LiTT) and stereotactic radiofrequency thermocoagulation (RF-TC), has enabled the efficient treatment of gelastic seizures in HH while minimizing the risks associated with craniotomies. Through bibliometric analysis, this study points out the direction for future HH research.

[Robotics and computer-assisted procedures in cranial neurosurgery]

BACKGROUND

The medical technical innovations over the last decade have made operations in the highly sensitive regions of the brain much safer.

OBJECTIVE

Presentation of how far computer assistance and robotics have become incorporated into clinical neurosurgery.

MATERIAL AND METHOD

Evaluation of the scientific literature and analysis of the certification status of the corresponding medical devices.

RESULTS

The rapid development of computer technology and the switch to digital imaging has led to the widespread introduction of neurosurgical planning software and intraoperative neuronavigation. In the field of robotics, the penetration into clinical neurosurgery is currently still largely limited to the automatic setting of trajectories.

CONCLUSION

The digitalization of imaging has fundamentally transformed neurosurgery. In the field of cranial neurosurgery, computer-assisted procedures can now be distinguished from noncomputer-assisted procedures only in a handful of cases. In the coming years important innovations for the clinical implementation can be expected in the field of robotics.

Magnetic Resonance-Guided Laser Interstitial Thermal Therapy for Hypothalamic Hamartoma: Surgical Approach and Treatment Outcomes

Hypothalamic hamartoma (HH) is a rare lesion consisting of normal neurons and neuroglia arranged in an abnormal pattern which usually causes gelastic seizures (GS). Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) has been developed as a minimally invasive approach to treat HH and gradually become a first-line treatment. In total, this study enrolled 47 consecutive HH patients that underwent one round of ablation. Patients were followed for at least one year. Patients' medical records and surgical information were carefully reviewed, and univariate analyses were performed. Of the treated patients, 72.3% remained GS-free in this study, with an overall Engel class I rate of 68.1%. Long-term postoperative complications occurred in six patients. Factors associated with GS prognosis included Delalande classification (p = 0.033), HH volume (p = 0.01), and the ablation rate of the HH body (p = 0.035). The disconnection rate was 0.73 ± 0.14 in the Engel class Ia group as compared to 0.62 ± 0.13 in the Engel Ib-Engel IV group (p = 0.046). MRgLITT represents a safe and effective surgical procedure. Patients with larger or Delalande type IV HH may require multiple rounds of ablation. In addition to assessing the degree of disconnection, ablation volume should also be carefully considered for patients undergoing this procedure.

Minimally invasive procedures for hypothalamic hamartoma–related epilepsy: a systematic review and meta-analysis

OBJECTIVE

Hypothalamic hamartoma (HH) is a rare, nonmalignant, heterotopic developmental malformation that consists of a mixture of normal neurons and glial cells. Resection of HHs has been associated with high rates of mortality and morbidity. Therefore, minimally invasive ablation methods could be the best treatment option for HH. The most frequently used minimally invasive options for HH ablation are radiofrequency thermocoagulation (RFT), laser ablation (LA), and stereotactic radiosurgery.

METHODS

To investigate three minimally invasive procedures in the treatment of refractory seizures related to HH, the authors conducted a systematic search in March 2022 in the MEDLINE, Embase, Scopus, and Web of Science databases in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Seizure freedom was the primary outcome of interest. The authors defined seizure freedom as Engel class I or International League Against Epilepsy class 1 or 2 or as the reported term “seizure freedom.” The secondary outcome was long-term complications reported in studies. Both random- and fixed-effects models were used to calculate the pooled proportion of seizure freedom and complication rate with 95% confidence intervals. A modified version of the Joanna Briggs Institute (JBI) Critical Appraisal to assess the risk of bias was used.

RESULTS

The authors included 15 studies with 422 patients (RFT, n = 190; LA, n = 171; and Gamma Knife Radiosurgery [GKRS], n = 61). Generally, the mean incidences of overall seizure freedom after minimally invasive procedures were 77% (95% CI 0.74–0.81) and 68% (95% CI 0.57–0.79) using fixed- and random-effects models, respectively. The mean incidence of overall seizure freedom after RFT was 69% (95% CI 0.63–0.75), and the mean incidences of overall seizure freedom after LA and GKRS were 87% (95% CI 0.82–0.92) and 44% (95% CI 0.32–0.57), respectively. The total complication rate with minimally invasive procedures was 13% (95% CI 0.01–0.26). The complication rate in each treatment was as follows: 5% (95% CI 0.0–0.12) for RFT, 20% (95% CI 0.0–0.47) for LA, and 22% (95% CI 0–0.65) for GKRS. Meta-regression analysis showed an association between older age and higher complication rates in the LA group.

CONCLUSIONS

In this meta-analysis, LA showed superiority in seizure freedom over the other two methods. The complication rate associated with RFT was less than those in the other two methods; however, this difference was not statistically significant.

Image-guided LINAC radiosurgery in hypothalamic hamartomas

Introduction

Hypothalamic hamartomas (HH) are developmental malformations that are associated with mild to severe drug-refractory epilepsy. Stereotactic radiosurgery (SRS) is an emerging non-invasive option for the treatment of small and medium-sized HH, providing good seizure outcomes without neurological complications. Here, we report our experience treating HH with frameless LINAC SRS.

Materials and methods

We retrospectively collected clinical and neuroradiological data of ten subjects with HH-related epilepsy that underwent frameless image-guided SRS.

Results

All patients underwent single-fraction SRS using a mean prescribed dose of 16.27 Gy (range 16–18 Gy). The median prescription isodose was 79% (range 65–81 Gy). The mean target volume was 0.64 cc (range 0.26–1.16 cc). Eight patients experienced complete or near complete seizure freedom (Engel class I and II). Five patients achieved complete seizure control within 4 to 18 months after the treatment. Four patients achieved Engel class II outcome, with stable results. One patient had a reduction of seizure burden superior to 50% (Engel class III). One patient had no benefit at all (Engel class IV) and refused further treatments. Overall, at the last follow-up, three patients experience class I, five class II, one class III and one class IV outcome. No neurological complications were reported.

Conclusions

Frameless LINAC SRS provides good seizure and long-term neuropsychosocial outcome, without the risks of neurological complications inherently associated with microsurgical resection.

Comparison of Surgical Outcomes in Individuals With Hypothalamic Hamartoma Alone or With Other Potentially Epileptogenic Focal Lesions

BACKGROUND

Hypothalamic hamartoma is a rare condition associated with refractory seizures. It can occur in isolation or with additional epileptogenic lesions. The aim of this study was to investigate the effects of additional potentially epileptogenic lesions on surgical outcomes in individuals with hypothalamic hamartoma.

METHODS

We conducted a chart review of 112 patients with hypothalamic hamartoma who underwent magnetic resonance imaging (MRI)-guided laser interstitial thermal therapy targeted to the hypothalamic hamartoma. We compared surgical outcomes after at least six months of postoperative follow-up (N = 65) between patients with hypothalamic hamartoma alone and those with hypothalamic hamartoma plus additional potentially epileptogenic lesions.

RESULTS

Sixteen out of 112 (14%) patients had additional epileptogenic lesions, including focal cortical dysplasia, gray matter heterotopia, and polymicrogyria. Ten out of 16 patients with additional lesions and 55 out of 96 patients with hypothalamic hamartoma alone had more than six months of follow-up and are included in the outcome analysis. Mean follow-up in these patients is 21.5 ± 17.3 months (standard deviation, range: 7.3-76.8 months) for patients with hypothalamic hamartoma alone and 16.1 ± 15.0 months (standard deviation, range: 6.6-58.2 months) for those with hypothalamic hamartoma plus additional epileptogenic lesions. Fewer patients with hypothalamic hamartoma plus other lesions had Engel class I/II outcomes than patients with hypothalamic hamartoma alone (5/10 [50%] vs 46/55 [83.6%]; P = 0.031).

CONCLUSIONS

MRI-guided laser interstitial thermal therapy remains an effective treatment option for patients with hypothalamic hamartoma. However, the outcome of surgical procedures targeted to the hypothalamic hamartoma may be less favorable in patients who have hypothalamic hamartoma coexisting with other potentially epileptogenic focal lesions. Thus, an additional surgical workup is warranted for these patients who have failed surgical treatment of hypothalamic hamartoma.

Laser Interstitial Thermal Therapy for Cavernous Malformations: A Systematic Review

Background

Microsurgical resection of intracranial cavernous malformations (CM) is regarded as the standard treatment, but in recent years, there has been a trend toward minimally invasive procedures like ablation of such lesions by using laser interstitial thermal therapy (LITT).

Methods

A systematic search using keywords ‘laser interstitial thermal therapy’ OR ‘LITT’ AND ‘cavernoma’ OR ‘cavernous angiomas’ OR ‘cavernous malformations’ was conducted in MEDLINE (PubMed), Scopus, Embase, and Cochrane electronic bibliographic databases and studies reporting the outcome of LITT procedure on intracranial CM were included. The demographic data, symptoms of patients, location and size of the lesion, and surgical outcome were extracted from the articles.

Result

Six studies, reporting the outcome of 33 patients were included in this review. In 26 patients, CM was identified as the epileptogenic foci and in others, CM was the source of headache or focal neurological deficits. LITT led to a satisfactory outcome in all patients except for three who achieved improvement in symptoms after the open resection of the lesion. Most of the post-operative complications were transient and resolved at the time of the last follow up. Cyst formation at the previous ablated CM site was reported as the long-term complication of LITT in one case.

Conclusion

LITT can provide a comparable outcome to the open resection of CMs, by having less invasiveness, even in deep and eloquent area lesions, and complications that are often temporary and disappear gradually. However, technical issues, such as thermal monitoring during the procedure, are considered a challenge for this procedure in CMs. Further studies with a larger population are needed to report this method's long-term outcome and complications on CMs.

A Special Approach for Stereotactic Radiofrequency Thermocoagulation of Hypothalamic Hamartomas With Bilateral Attachments to the Hypothalamus: The Transthird Ventricular Approach to the Contralateral Attachment

BACKGROUND

Disconnection surgery for the treatment of epileptic hypothalamic hamartomas (HHs) is strategically difficult in cases with complex-shaped HHs, especially with bilateral hypothalamic attachments, despite its effectiveness.

OBJECTIVE

To evaluate the feasibility of a new approach for stereotactic radiofrequency thermocoagulation (SRT) using penetration of the third ventricle (SRT-TT) aiming to disconnect bilateral hypothalamic attachments in a single-staged, unilateral procedure.

METHODS

Ninety patients (median age at surgery, 5.0 years) who had HHs with bilateral hypothalamic attachments and were followed for at least 1 year after their last SRT were retrospectively reviewed.

RESULTS

Thirty-three patients underwent SRT-TT as initial surgery. Of the 58 patients after mid-2013 when SRT-TT was introduced, 33 underwent SRT-TT and 12 (20.7%) required reoperation (ReSRT), whereas 20 of 57 patients (35.1%) without SRT-TT underwent reoperation. Reoperation was required in significantly fewer patients after mid-2013 (n = 12 of 58, 20.7%) than before mid-2013 (n = 15 of 32, 46.9%) (P = .01). Final seizure freedoms were not different between before and after mid-2013 (gelastic seizure freedom, n = 30 [93.8%] vs n = 49 [84.5%] and other types of seizure freedom, n = 21 of 31 [67.7%] vs n = 32 of 38 [84.2%]). Persistent complications were less in SRT-TT than in ReSRT using the bilateral approach, but not significantly. However, hormonal replacement was required significantly more often in ReSRT using the bilateral approach (4 of 9, 44.4%) than in SRT-TT (3 of 32, 9.4%) (P = .01).

CONCLUSION

SRT-TT enabled disconnection of bilateral attachments of HHs in a single-staged procedure, which reduced the additional invasiveness of reoperation. Moreover, SRT-TT reduced damage to the contralateral hypothalamus, with fewer endocrinological complications than the bilateral approach.

Increased Gray Matter Density in the Right Mesencephalic Tegmentum Is Associated With Better Engel Classes I and II After Radiosurgery for Hypothalamic Hamartomas

BACKGROUND

Hypothalamic hamartomas (HHs) are disabling congenital lesions, responsible for gelastic seizures frequently associated with catastrophic epilepsies, epileptogenic encephalopathy, and cognitive and psychiatric severe comorbidities. Stereotactic radiosurgery (SRS) is a well-established minimally invasive therapeutic approach.

OBJECTIVE

To assess whether pretherapeutic gray matter density (GMD) correlates with seizure outcome.

METHODS

We used voxel-based morphometry at whole-brain level, as depicted on pretherapeutic standard structural magnetic resonance neuroimaging. We examined 24 patients (10 male patients, 14 female patients; mean age, 12.7 yr; median, 9; range, 5.9-50) treated in Marseille University Hospital, France, between May 2001 and August 2018.

RESULTS

Most relevant anatomic area predicting postoperative Engel classes I and II vs III and IV after SRS for HHs was mesencephalic tegmentum. Higher pretherapeutic GMD in this area was associated with better outcomes for seizure cessation. The only other statistically significant clusters were right cerebellar lobule VIIIb and VIIIa. Lower pretherapeutic GMD in both clusters correlated with better Engel class outcomes. GMD decreased with age in the left mediodorsal thalamus.

CONCLUSION

Seizure cessation after SRS for HHs was associated with higher GMD in mesencephalic tegmental area, acknowledged to be involved in the neural control of explosive vocal behavior in animals. This area is connected by the mamillotegmental bundle to the lateral tuberal nucleus area of the hypothalamus, where HHs are known to rise. In the future, the detection of more gray matter in this "laugh" tegmental area based on pretherapeutic routine structural neuroimaging might help in patient selection for minimally invasive radiosurgery for HH.

The American Society for Stereotactic and Functional Neurosurgery Position Statement on Laser Interstitial Thermal Therapy for the Treatment of Drug-Resistant Epilepsy

Magnetic resonance image-guided laser interstitial thermal therapy (MRgLITT) is a novel tool in the neurosurgical armamentarium for the management of drug-resistant epilepsy. Given the recent introduction of this technology, the American Society for Stereotactic and Functional Neurosurgery (ASSFN), which acts as the joint section representing the field of stereotactic and functional neurosurgery on behalf of the Congress of Neurological Surgeons and the American Association of Neurological Surgeons, provides here the expert consensus opinion on evidence-based best practices for the use and implementation of this treatment modality. Indications for treatment are outlined, consisting of failure to respond to, or intolerance of, at least 2 appropriately chosen medications at appropriate doses for disabling, localization-related epilepsy in the setting of well-defined epileptogenic foci, or critical pathways of seizure propagation accessible by MRgLITT. Applications of MRgLITT in mesial temporal lobe epilepsy and hypothalamic hamartoma, along with its contraindications in the treatment of epilepsy, are discussed based on current evidence. To put this position statement in perspective, we detail the evidence and authority on which this ASSFN position statement is based.

Surgical outcomes between temporal, extratemporal epilepsies and hypothalamic hamartoma: systematic review and meta-analysis of MRI-guided laser interstitial thermal therapy for drug-resistant epilepsy

BACKGROUND

Approximately 1/3 of patients with epilepsy have drug-resistant epilepsy (DRE) and require surgical interventions. This meta-analysis aimed to review the effectiveness of MRI-guided laser interstitial thermal therapy (MRgLITT) in DRE.

METHODS

The Population, Intervention, Comparator and Outcome approach and Preferred Reporting Items for Systematic Reviews and Meta-Analyses were followed. PubMed, MEDLINE and EMBASE databases were systematically searched for English language publications from 2012 to Nov 2020. Data on the prevalence outcome using the Engel Epilepsy Surgery Outcome Scale (Class I-IV), and postoperative complications were analysed with 95% CIs.

RESULTS

Twenty-eight studies that included a total of 559 patients with DRE were identified. The overall prevalence of Engel class I outcome was 56% (95% CI 0.52% to 0.60%). Hypothalamic hamartomas (HH) patients had the highest seizure freedom rate of 67% (95% CI 0.57% to 0.76%) and outcome was overall comparable between mesial temporal lobe epilepsy (mTLE) (56%, 95% CI 0.50% to 0.61%) and extratemporal epilepsy (50% 95% CI 0.40% to 0.59%). The mTLE cases with mesial temporal sclerosis had better outcome vs non-lesional cases of mTLE. The prevalence of postoperative adverse events was 19% (95% CI 0.14% to 0.25%) and the most common adverse event was visual field deficits. The reoperation rate was 9% (95% CI 0.05% to 0.14%), which included repeat ablation and open resection.

CONCLUSION

MRgLITT is an effective and safe intervention for DRE with different disease aetiologies. The seizure freedom outcome is overall comparable in between extratemporal and temporal lobe epilepsy; and highest with HH.

TRAIL REGISTRATION NUMBER

The study protocol was registered with the National Institute for Health Research (CRD42019126365), which serves as a prospective register of systematic reviews. It is an international database of prospectively registered systematic reviews with a focus on health-related outcomes. Details about the protocol can be found at https://wwwcrdyorkacuk/PROSPERO/.

Microsurgical management of complex hypothalamic hamartomas in the era of minimally invasive therapy: a case series and narrative review

INTRODUCTION

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, ultimately necessitating craniotomies.

METHODS

All patients who underwent microsurgical resection of a complex HH by the 2 senior authors from 2011-2021 were included. Charts were retrospectively reviewed and demographic, clinical, imaging, and outcome data were recorded.

RESULTS

8 patients (mean age 7 years) were included. 2 had failed previous treatments. All 7 presented with gelastic seizures and cognitive dysfunction, 6 exhibited central precocious puberty, and 3 had behavioral problems. 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 (FTOZ) 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), 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 (2-66), 7 patients remain seizure-free, while 1 has rare seizures. Cognitive and behavioral symptoms improved in all patients.

CONCLUSION

For large HH with interpeduncular extension, microsurgery via the FTOZ approach is a safe and highly effective treatment modality.

[Surgical treatment of epilepsy in patients with hypothalamic hamartomas]

The purpose of this review was to analyze the current ideas about various techniques and methods for treating epilepsy in patients with hypothalamic hamartomas including microsurgery, endoscopy, radiofrequency thermal destruction, stereotactic laser ablation and radiosurgery. Data characterizing their effectiveness, limitations and complications are considered.

CONCLUSION

When choosing the optimal treatment option, it is necessary to take into account patient age and course of disease, anatomical and topographic features of hamartoma location, previous attempts of treatment, opinion of the patient and his guardians, as well as surgical experience.

Safety and Efficacy of Primary Hypofractionated Gamma Knife Radiosurgery for Giant Hypothalamic Hamartoma

OBJECTIVE

To describe the feasibility, safety, efficacy, and complication profile of primary hypofractionated gamma knife radiosurgery (GKRS), and practical nuances of performing the same in pediatric patients.

METHODS

Three pediatric patients (age range 17-65 mo) underwent primary hypofractionated GKRS in 2-3 consecutive days with interfraction interval of 24 h. All patients had precocious puberty and were on GnRH analogue. Frame based GKRS done with 8.1-9.2 Gy radiation per fraction at 50% isodose in 2-3 fractions targeting the entire hamartoma volume. The mean target volume was 5.67 cc (4.45-7.39 cc). The authors followed these patients for clinical and endocrinological assessment at every 6 mo interval while the repeat MRI done at 6 mo and then annually. The seizure outcome analysis was done using Engel scale.

RESULTS

At a mean follow up of 27 mo (24-30 mo), 2 patients became Engel class 3 while one achieved Engel class 1 control. 2 patients showed halted pubertal growth with no additional hormonal aberration. 2 patients showed significant volumetric reduction (48% and 32%) and patchy necrosis inside the hypothalamic hamartoma (HH). There was no deficit in visual function, memory and cognition. One patient showed reduction in aggressiveness.

CONCLUSION

Giant HH are exceptionally difficult neurological diseases. Primary hypofractionated GKRS may be an alternative approach as mono/multitherapy with promising results and minimal complication.

Smaller Knife, Fewer Seizures? Recent Advances in Minimally Invasive Techniques in Pediatric Epilepsy Surgery

Children with drug-resistant epilepsy are at high risk for developmental delay, increased mortality, psychiatric comorbidities, and requiring assistance with activities of daily living. Despite the advent of new and effective pharmacologic therapies, about one in 5 children will develop drug-resistant epilepsy, and most of these children continue to have seizures despite trials of other medication. Epilepsy surgery is often a safe and effective option which may offer seizure freedom or at least a significant reduction in seizure burden in many children. However, despite published evidence of safety and efficacy, epilepsy surgery remains underutilized in the pediatric population. Patient and family fears about the risks of surgery may contribute to this gap. Less invasive surgical techniques may be more palatable to children with epilepsy and their caregivers. In this review, we present recent advances in minimally invasive techniques for the surgical treatment of epilepsy as well as intriguing possibilities for the future. We describe the indications for, benefits of, and limits to minimally-invasive techniques including Stereo-encephalography, laser interstitial thermal ablation, deep brain stimulation, focused ultrasound, stereo-encephalography-guided radiofrequency ablation, endoscopic disconnections, and responsive neurostimulation.

Long-term seizure outcomes in patients with hypothalamic hamartoma treated by stereotactic radiofrequency thermocoagulation

OBJECTIVE

To investigate long-term seizure outcomes in patients with hypothalamic hamartoma (HH) following stereotactic radiofrequency thermocoagulation (SRT).

METHODS

A total of 131 patients with HH who underwent SRT and were followed for at least three years after the last SRT were enrolled. Seizure outcomes were evaluated for gelastic seizures (GS) and other types of seizures (nGS) separately using the International League Against Epilepsy classification. Classes 1 and 2 were considered seizure-free. Kaplan-Meier survival analyses were used to estimate the proportion remaining seizure-free after the first and last SRTs. Risk factors relating to outcomes were analyzed by log-rank tests and a multivariate Cox proportional hazards model.

RESULTS

Reoperation was performed in 34 patients (26.2%). Median total follow-up was 61 (range, 36-202) months. Seizure freedom was obtained in 116 patients (88.6%) for GS and 85 of 108 patients (78.7%) for nGS at the last follow-up. Mean GS-free survival times improved from after the first (64.1 [95%CI 57.3-70.9] months) to after the last SRT (80.2 [95%CI 75.7-84.8] months). About 90% of GS recurrences after the first SRT were found within 6 months, though a few patients recurred more than 2 years after the first SRT. On the other hand, mean nGS-free survival times after the first and last SRTs were not different between after the first SRT (84.4 [95%CI 73.0-90.7] months) and after the last SRT (83.1 [95%CI 74.1-92.0] months). There was no factor related to GS outcomes, but the significant factor for nGS-free survival after the last SRT was multiple previous treatments (p=0.01, hazard ratio=15.65, 95%CI 1.79-137.16).

SIGNIFICANCE

The last SRT was almost equivalent to achieving complete disconnection of HHs from the hypothalamus according to our strategy. Considering the epileptogenic network, GS outcomes depend on complete disconnection, whereas nGS outcomes are not affected by surgical factors but independency of secondary epileptogenesis.

Current applications and safety profile of laser interstitial thermal therapy in the pediatric population: a systematic review of the literature

OBJECTIVE

Laser interstitial thermal therapy (LITT) provides a minimally invasive alternative to open brain surgery, making it a powerful neurosurgical tool especially in pediatric patients. This systematic review aimed to highlight the indications and complications of LITT in the pediatric population.

METHODS

In line with the PRISMA guidelines, the authors conducted a systematic review to summarize the current applications and safety profiles of LITT in pediatrics. PubMed and Embase were searched for studies that reported the outcomes of LITT in patients < 21 years of age. Retrospective studies, case series, and case reports were included. Two authors independently screened the articles by title and abstract followed by full text. Relevant variables were extracted from studies that met final eligibility, and results were pooled using descriptive statistics.

RESULTS

The selection process captured 303 pediatric LITT procedures across 35 studies. Males comprised approximately 60% of the aggregate sample, with a mean age of 10.5 years (range 0.5-21 years). The LITT technologies used included Visualase (89%), NeuroBlate (9%), and Multilase 2100 (2%). The most common indication was treatment of seizures (86%), followed by brain tumors (16%). The mean follow-up duration was 15.6 months (range 1.3-48 months). The overall complication rate was 15.8%, which comprised transient neurological deficits, cognitive and electrolyte disturbances, hemorrhage, edema, and hydrocephalus. No deaths were reported.

CONCLUSIONS

As of now, LITT's most common applications in pediatrics are focused on treating medically refractory epilepsy and brain tumors that can be difficult to resect. The safety of LITT can provide an attractive alternative to open brain surgery in the pediatric population.

Does the Modified Arrhenius Model Reliably Predict Area of Tissue Ablation After Magnetic Resonance-Guided Laser Interstitial Thermal Therapy for Pediatric Lesional Epilepsy?

BACKGROUND

Commercial magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) systems utilize a generalized Arrhenius model to estimate the area of tissue damage based on the power and time of ablation. However, the reliability of these estimates in Vivo remains unclear.

OBJECTIVE

To determine the accuracy and precision of the thermal damage estimate (TDE) calculated by commercially available MRgLITT systems using the generalized Arrhenius model.

METHODS

A single-center retrospective review of pediatric patients undergoing MRgLITT for lesional epilepsy was performed. The area of each lesion was measured on both TDE and intraoperative postablation, postcontrast T1 magnetic resonance images using ImageJ. Lesions requiring multiple ablations were excluded. The strength of the correlation between TDE and postlesioning measurements was assessed via linear regression.

RESULTS

A total of 32 lesions were identified in 19 patients. After exclusion, 13 pairs were available for analysis. Linear regression demonstrated a strong correlation between estimated and actual ablation areas (R2 = .97, P < .00001). The TDE underestimated the area of ablation by an average of 3.92% overall (standard error (SE) = 4.57%), but this varied depending on the type of pathologic tissue involved. TDE accuracy and precision were highest in tubers (n = 3), with average underestimation of 2.33% (SE = 0.33%). TDE underestimated the lesioning of the single hypothalamic hamartoma in our series by 52%. In periventricular nodular heterotopias, TDE overestimated ablation areas by an average of 13% (n = 2).

CONCLUSION

TDE reliability is variably consistent across tissue types, particularly in smaller or periventricular lesions. Further investigation is needed to understand the accuracy of this emerging minimally invasive technique.

Emerging indications for stereotactic laser interstitial thermal therapy in pediatric neurosurgery

Surgical treatment of deep or difficult to access lesions represents a unique and significant challenge for pediatric neurosurgeons. The introduction of stereotactic magnetic resonance-guided laser interstitial thermal therapy (LITT) over the last decade has had a dramatic impact on the landscape of pediatric neurosurgery. LITT provides a safe and effective option for children with epilepsy from hypothalamic hamartoma that represents a ground-breaking new therapy for a condition which was historically very difficult to treat with previous neurosurgical techniques. LITT has also been used as an alternative surgical technique for mesial temporal sclerosis, focal cortical dysplasia, MR-negative epilepsy, cavernoma-related epilepsy, insular epilepsy, and corpus callosotomy among other epilepsy etiologies. In some cases, LITT has been associated with improved cognitive outcomes compared to standard techniques, as in mesial temporal lobe epilepsy. Initial experiences with LITT for neuro-oncologic processes are also promising. LITT is often attractive to patients and providers as a minimally invasive approach, but the differences in safety and clinical outcome between LITT and traditional approaches are still being studied. In this review, we examine the emerging indications and clinical evidence for LITT in pediatric neurosurgery.

Stereotactic radiofrequency thermocoagulation and resective surgery for patients with hypothalamic hamartoma

OBJECTIVE

In this study, the authors compared the efficacy and safety of stereotactic radiofrequency thermocoagulation (SRT) and resective surgery (RS) for patients with hypothalamic hamartoma (HH).

METHODS

The authors included all patients with HHs who were treated by SRT or hamartoma resection. Seizure outcomes were assessed by blinded observers according to the International League Against Epilepsy (ILAE) classification. Favorable seizure outcomes were defined as ILAE classes 1 and 2, and unfavorable seizure outcomes were defined as ILAE classes 3-6.

RESULTS

Twenty-nine patients who underwent SRT or RS met the inclusion criteria; 3 were excluded because they had completed less than 12 months of follow-up. Most of the patients (20 of 26; 76.9%) had small HHs (i.e., maximum HH diameter less than 20 mm). The patients' follow-up time ranged from 12 to 66 months (median 60 months). At the last follow-up, favorable outcomes were observed in 9 patients (69.2%) who had undergone SRT and 10 patients (76.9%) who had undergone HH resection. No significant difference was found in seizure outcomes between SRT and RS recipients. Patients with giant HHs were more likely than patients with smaller tumors to undergo multiple resections (p = 0.043, univariate logistic regression; significant). However, no significant difference was found between SRT and RS recipients in terms of the number of procedures per patient. SRT recipients had fewer and less-severe adverse events than RS recipients.

CONCLUSIONS

For patients with small HHs, SRT provides similar seizure outcomes to RS with a less invasive procedure. Patients who underwent SRT experienced fewer and lighter adverse effects than patients who had RS. Patients with giant HHs were more likely to undergo multiple HH resections.

Magnetic Resonance Imaging-Guided Laser Interstitial Thermal Therapy for Epilepsy: Systematic Review of Technique, Indications, and Outcomes

BACKGROUND

For patients with focal drug-resistant epilepsy (DRE), surgical resection of the epileptogenic zone (EZ) may offer seizure freedom and benefits for quality of life. Yet, concerns remain regarding invasiveness, morbidity, and neurocognitive side effects. Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) has emerged as a less invasive option for stereotactic ablation rather than resection of the EZ.

OBJECTIVE

To provide an introduction to MRgLITT for epilepsy, including historical development, surgical technique, and role in therapy.

METHODS

The development of MRgLITT is briefly recounted. A systematic review identified reported techniques and indication-specific outcomes of MRgLITT for DRE in human studies regardless of sample size or follow-up duration. Potential advantages and disadvantages compared to available alternatives for each indication are assessed in an unstructured review.

RESULTS

Techniques and outcomes are reported for mesial temporal lobe epilepsy, hypothalamic hamartoma, focal cortical dysplasia, nonlesional epilepsy, tuberous sclerosis, periventricular nodular heterotopia, cerebral cavernous malformations, poststroke epilepsy, temporal encephalocele, and corpus callosotomy.

CONCLUSION

MRgLITT offers access to foci virtually anywhere in the brain with minimal disruption of the overlying cortex and white matter, promising fewer neurological side effects and less surgical morbidity and pain. Compared to other ablative techniques, MRgLITT offers immediate, discrete lesions with real-time monitoring of temperature beyond the fiber tip for damage estimates and off-target injury prevention. Applications of MRgLITT for epilepsy are growing rapidly and, although more evidence of safety and efficacy is needed, there are potential advantages for some patients.

One-Stage High-Density Focal Stereo-Array SEEG-Guided Radiofrequency Thermocoagulation for the Treatment of Pediatric Giant Hypothalamic Hamartomas

Background: Giant hypothalamic hamartomas (HHs) are extremely rare lesions, for which the treatment is challenging. While minimally invasive treatments such as radiofrequency thermal coagulation and laser ablation have improved seizure outcomes, multiple operations are often required. This study investigated the value of one-stage stereo-array radiofrequency thermocoagulation based on stereotactic electroencephalography (SEEG) for pediatric giant HHs.

Methods: We analyzed the clinical data of six patients with giant HHs (masses with a maximum diameter >30 mm) who underwent stereotactic electrode implantation between November 2017 and April 2019. After a multidisciplinary discussion, we designed a high-density focal stereo-array electrode implantation strategy. SEEG-guided bipolar coagulations were performed between two contiguous contacts of the same electrode, or between two adjacent contacts of different electrodes.

Results: Among the six patients, three were male and three were female, with an average age of 5.08 ± 4.73 years (range, 1.4–12 years); the average follow-up duration was 20.17 ± 5.49 months. One patient had previously undergone open surgery. Four patients had gelastic seizures, one had gelastic and tonic seizures, and one had gelastic and generalized tonic-clonic seizures. The number of implanted electrodes ranged from 3 to 7, with an average of 5.33. One patient had transient diabetes insipidus after the operation, and no child had fever or new hormone metabolisms disorder after surgery. Four patients had Engel I classification outcomes (free from disabling seizures), and two patients had Engel II classification outcomes.

Conclusion: Although the exploration of epileptic activity and the extent of ablation are limited by the number of SEEG electrodes for the complete disconnection. One-stage high-density focal stereo-array SEEG-guided radiofrequency was safe and effective for treating pediatric giant HH patients. It can be an alternative method to treat giant HHs where LITT is unavailable.

Highly realistic simulation for robot-assisted hypothalamic hamartoma real-time MRI-guided laser interstitial thermal therapy (LITT)

PURPOSE

Real-time MRI-guided laser interstitial thermal therapy (LITT) is a challenging procedure due to its technical complexity, as well as the need for efficient multidisciplinary teamwork and transfer of an anesthetized patient between operating room (OR) and magnetic resonance (MR). A highly realistic simulation was developed to design the safest process before being applied to real patients. In this report, authors address the description of the methodology used for this simulation and its purposefulness.

METHODS

The entire image planning, anesthetic, and surgical process were performed on a modified pediatric simulation mannequin with a brain made of medical grade silicone including a hypothalamic hamartoma. Preoperative CT and MR were acquired. Stereotactic insertion of the optical fiber was assisted by the Neuromate® stereotactic robot. Laser ablation was performed with the Medtronic Visualase® MRI-guided system in a 3T Phillips Ingenia® MR scanner. All the stages of the process, participants, and equipment were the same as planned for a real surgery.

RESULTS

No critical errors were found in the process design that prevented the procedure from being performed with adequate safety. Specific proposals for team positioning and interaction in patient transfers and in MR room were validated. Some specific elements that could improve safety were identified.

CONCLUSION

Highly realistic simulation has been an extremely useful tool for safely planning LITT, because professionals were able to take actions in the workflow based not on ideas but on lived experiences. It contributed definitively to build a well-coordinated surgical team that worked safely and more efficiently.

Surgical treatment of hypothalamic hamartomas

Hypothalamic hamartomas are aberrant masses, composed of abnormally distributed neurons and glia. Along endocrine and cognitive symptoms, they may cause epileptic seizures, including the specific gelastic and dacrystic seizures. Surgery is the treatment of drug-resistant hamartoma epilepsy, with associated positive results on endocrine, psychiatric, and cognitive symptoms. Recently, alternatives to open microsurgical treatment have been proposed. We review these techniques and compare their efficacy and safety. Open resection or disconnection of the hamartoma, either through pterional, transcallosal, or transventricular approach, leads to good epileptological control, but its high complication rate, up to 30%, limits its indications. The purely cisternal peduncular forms remain the only indication of open, pterional approach, while other strategies have been developed to overcome the neurological, endocrine, behavioral, or cognitive complications. Laser and radiofrequency thermocoagulation-based disconnection through robot-guided stereo-endoscopy has been proposed as an alternative to open microsurgical resection and stereotactic destruction. The goal is to allow safe and complete disconnection of a possibly complex attachment zone, through a single intraparenchymal trajectory which allows multiple laser or radiofrequency probe trajectory inside the ventricle. The efficacy was high, with 78% of favorable outcome, and the overall complication rate was 8%. It was especially effective in patients with isolated gelastic seizures and pure intraventricular hamartomas. Stereotactic radiosurgery has proved as efficacious and safer than open microsurgery, with around 60% of seizure control and a very low complication rate. Multiple stereotactic thermocoagulation showed very interesting results with 71% of seizure freedom and 2% of permanent complications. Stereotactic laser interstitial thermotherapy (LiTT) seems as effective as open microsurgery (from 76 to 81% of seizure freedom) but causes up to 20% of permanent complications. This technique has however been highly improved by targeting only the epileptogenic onset zone in the hamartoma, as shown on preoperative functional MRI, leading to an improvement of epilepsy control by 45% (92% of seizure freedom) with no postoperative morbidity. All these results suggest that the impact of the surgical procedure does not depend on purely technical matters (laser vs radiofrequency thermocoagulation or stereotactic vs robot-guided stereo-endoscopy) but relies on the understanding of the epileptic network, including inside the hamartoma, the aim being to plan an effective disconnection or lesion of the epileptogenic part while sparing the adjacent functional structures.

Identification and Management of Progressive Enhancement After Radiation Therapy for Brain Metastases: Results from a Neurosurgical Survey

OBJECTIVE

There is a lack of consensus regarding diagnosis, timing, and method of intervention for progressive enhancement on surveillance imaging after stereotactic radiosurgery (SRS) treatment of brain metastases. We sought to characterize current practices among neurosurgeons in identifying and treating infield tumor recurrence (TR) or radiation necrosis (RN) after SRS for brain metastases.

METHODS

A voluntary survey was distributed electronically to preidentified neurosurgeons. Results were analyzed using descriptive statistics and χ² analysis.

RESULTS

A total of 120 participants completed the survey from 72 U.S. and 17 international centers. Most (69.2%) agreed that growth over ≥2 surveillance scans spaced ≥90 days apart identified irreversible progression after SRS for brain metastases. Respondents were evenly divided on the need for tissue biopsy to distinguish between TR and RN. Preferred treatment modality and time frame to initiate treatment of suspected RN differed among neurosurgeons based on SRS case volume for brain metastases (P = 0.002 and P = 0.02, respectively). Neurosurgeons who used magnetic resonance-guided laser interstitial thermal therapy (LITT) for brain metastases were more likely to prefer LITT for suspected RN, whereas those with minimal LITT experience preferred steroids (P < 0.0001). Neurosurgeons in the United States were more likely to prefer LITT for RN (37.3%) compared with international counterparts (0%).

CONCLUSIONS

Our survey of practicing neurosurgeons highlights areas of controversy in distinguishing between TR and RN and preferred management of suspected RN.

Hypothalamic hamartomas in adulthood: Clinical spectrum and treatment outcome-A unicenter experience

INTRODUCTION

Clinical manifestations of the hypothalamic hamartoma-epilepsy syndrome (HH-ES) in adulthood are variable. Efficacy of therapeutic options and outcome are diverse.

METHODS

Retrospective study of adult patients diagnosed with a HH in magnetic resonance imaging and epilepsy who attended our tertiary Epilepsy Unit between 2003 and 2018. We report the clinical and electroencephalographic features of a series of adult patients with HH and related epilepsy seen in our center together with the treatments and seizure outcome.

RESULTS

We describe a series of eight patients. Five males (62.5%), median age at evaluation was 28.5 years (IQR: 15.5). Clinical manifestations included focal with preserved and impaired awareness emotional seizures (gelastic seizures [GS]) in six patients (75%), focal tonic, atonic with impaired awareness and focal to bilateral tonic-clonic seizures. Mild GS were the only symptom in one patient. Three patients (37.5%) had endocrinological disturbances such as obesity and hypothyroidism. Fifty percent of the patients showed psychiatric comorbidity such as anxiety disorder and aggressiveness, and two patients had psychomotor delay. Seven patients (87.7%) had drug-resistant seizures and three of them were treated with radiosurgery. Out of the treated group, only one (33.3%) became seizure-free 2 years after surgery but developed psychiatric problems. The other two patients had an Engel IV outcome and received a vagal nerve stimulation (VNS) implant. VNS did not lead to changes either in intensity nor in seizure frequency.

CONCLUSIONS

Hypothalamic hamartoma-epilepsy syndrome clinical manifestations in adult patients are as variable as at pediatric age. Outcome of therapeutic options such as radiosurgery or VNS may be poorer at this stage.

Pathogenic variants of DYNC2H1, KIAA0556, and PTPN11 associated with hypothalamic hamartoma

OBJECTIVE

Intensive genetic analysis was performed to reveal comprehensive molecular insights into hypothalamic hamartoma (HH).

METHODS

Thirty-eight individuals with HH were investigated by whole exome sequencing, target capture-based deep sequencing, or single nucleotide polymorphism (SNP) array using DNA extracted from blood leukocytes or HH samples.

RESULTS

We identified a germline variant of KIAA0556, which encodes a ciliary protein, and 2 somatic variants of PTPN11, which forms part of the RAS/mitogen-activated protein kinase (MAPK) pathway, as well as variants in known genes associated with HH. An SNP array identified (among 3 patients) one germline copy-neutral loss of heterozygosity (cnLOH) at 6p22.3-p21.31 and 2 somatic cnLOH; one at 11q12.2-q25 that included DYNC2H1, which encodes a ciliary motor protein, and the other at 17p13.3-p11.2. A germline heterozygous variant and an identical somatic variant of DYNC2H1 arising from cnLOH at 11q12.2-q25 were confirmed in one patient (whose HH tissue, therefore, contains biallelic variants of DYNC2H1). Furthermore, a combination of a germline and a somatic DYNC2H1 variant was detected in another patient.

CONCLUSIONS

Overall, our cohort identified germline/somatic alterations in 34% (13/38) of patients with HH. Disruption of the Shh signaling pathway associated with cilia or the RAS/MAPK pathway may lead to the development of HH.

MRI-guided laser interstitial thermal therapy in an infant with tuberous sclerosis: technical case report

Cortical tubers associated with tuberous sclerosis complex (TSC) are potential epileptic foci that are often amenable to resective or ablative surgeries, and controlling seizures at a younger age may lead to improved functional outcomes. MRI-guided laser interstitial thermal therapy (MRgLITT) has become a popular minimally invasive alternative to traditional craniotomy. Benefits of MRgLITT include the ability to monitor the ablation in real time, a smaller incision, shorter hospital stay, reduced blood loss, and reduced postoperative pain. To place the laser probe for LITT, however, stereotaxy is required-which classically involves head fixation with cranial pins. This creates a relative minimum age limit of 2 years old because it demands a mature skull and fused cranial sutures. A novel technique is presented for the application of MRgLITT in a 6-month-old infant for the treatment of epilepsy associated with TSC. To the authors' knowledge this is the youngest patient treated with laser ablation. The authors used a frameless navigation technique with a miniframe tripod system and intraoperative reference points. This technique expands the application of MRgLITT to younger patients, which may lead to safer surgical interventions and improved outcomes for these children.

Postoperative Outcomes of Magnetic Resonance Imaging (MRI)-Guided Laser Interstitial Thermal Therapy (LITT) in the Treatment of Drug-Resistant Epilepsy: A Meta-Analysis

BACKGROUND Drug-resistant epilepsy is a common neurological disease in adults and children. This study aimed to undertake a systematic review of the literature with meta-analysis of the data from published studies to assess the effectiveness of magnetic resonance imaging (MRI)-guided laser interstitial thermal therapy (LITT) in treatment-resistant epilepsy. MATERIAL AND METHODS The study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PubMed, MEDLINE, and EMBASE databases were systematically searched for indexed publications in the English language up to May 2018. Data on the prevalence, outcome using the Engel Epilepsy Surgery Outcome Scale (Class I to IV), and postoperative complications were analyzed with 95% confidence intervals (CIs). The Methodological Index for Non-Randomized Studies (MINORS) was used to assess the risk of bias in the included studies. RESULTS Sixteen published studies that included a total of 269 patients with treatment resistant epilepsy were identified. The prevalence of Engel Class I, II, III and IV were 61% (95% CI, 0.54-0.68; I²=14.5%; P=0.302), 12% (95% CI, 0.07-0.16; I²=86.8%; P=0.000), 16% (95% CI, 0.10-0.22; I²=3.0%; P=0.397), and 15% (95% CI, 0.08-0.22; I²=13.2%; P=0.330), respectively. The prevalence of postoperative complications was 24% (95% CI, 0.16-0.32; I2=0%; P=0.629). CONCLUSIONS Meta-analysis of data from 16 studies that included 269 patients with treatment-resistant epilepsy showed that MRI-guided LITT significantly reduced the frequency of seizures and reduced postoperative complications, supporting the safety and effectiveness of MRI-guided LITT in the treatment of drug-resistant epilepsy.

Stereotactic laser ablation for nonlesional cingulate epilepsy: case report

Stereotactic laser ablation (SLA) is being increasingly used to treat refractory focal epilepsy, especially mesial temporal lobe epilepsy. However, emerging evidence suggests it can be used for extratemporal lobe epilepsy as well.The authors report the case of a 17-year-old male who presented with refractory nocturnal seizures characterized by bilateral arms stiffening or rhythmic jerking lasting several seconds. Semiology suggested an epileptogenic zone close to one of the supplementary sensory motor areas. Electroencephalography showed seizures arising from the central region without consistent lateralization. Brain imaging showed no abnormality. An invasive evaluation using bilateral stereoelectroencephalography (SEEG) was utilized in 2 steps, first to establish the laterality of seizures, and second to further cover the mesial cingulate region of the right hemisphere. Seizures arose from the middle portion of the right cingulate gyrus. Extraoperative electrical mapping revealed that the seizure onset zone was adjacent to eloquent motor areas. SLA targeting the right midcingulate gyrus was performed. The patient has remained seizure free since immediately after the procedure with no postoperative deficits (follow-up of 17 months).This case highlights the utility of SEEG in evaluating difficult-to-localize, focal epilepsy. It also demonstrates that the use of SLA can be extended to nonlesional, extratemporal epilepsies.

CyberKnife® Radiosurgery as First-line Treatment for Catastrophic Epilepsy Caused by Hypothalamic Hamartoma

Hypothalamic hamartomas (HH) are deep-seated lesions often associated with catastrophic epilepsy (an epileptic syndrome characterized by severe, drug-refractory seizures eventually leading to mental retardation and death). Radical microsurgical resection is not feasible for lesions located within the wall of the third ventricle inside the hypothalamus. Frame-based stereotactic radiosurgery has been reported as an effective treatment modality for small- to medium-size intrahypothalamic hamartomas, providing excellent seizure outcomes without lasting complications. This report describes the use of frameless image-guided robotic radiosurgery (CyberKnife® Radiosurgery System) as a first-line treatment in two children with catastrophic epilepsy induced by HH. Both patients experienced multiple-daily complex partial and gelastic seizures, as well as almost daily generalized seizures. The prescribed dose was 16 Gy (to the 65% isodose for case I; to the 70% isodose for case II). Lesional volume was 11.5 cc (case I) and 8.9 cc (case II). A steady reduction of the seizure frequency and severity was achieved after the treatment, starting about three months after the treatment. The generalized seizures disappeared within one year, while complete resolution of the gelastic seizures required up to 18 months. No seizure recurrence and no radiation-induced side effects or complications were witnessed over a follow-up period of ten years and eight months (case I) and nine years and seven months (case II) since the treatment. CyberKnife radiosurgery proved to be a safe and effective non-invasive first-line treatment in these two children with catastrophic epilepsy caused by HH.

Computational analysis of linear energy modulation for laser thermal coagulation

Accurate treatment planning and monitoring are critical factors to ensure safe and effective outcomes of laser thermal coagulation (LTC). Computational and experimental models based upon linear energy modulation were deployed to predict temperature distribution and thermal damage within ex vivo porcine liver. 1470-nm Gaussian emission was confirmed by using digital imaging and the customized goniometry. The tissue temperature was maintained in the pre-determined range (65~75 °C) to induce thermally destructive volumes of 0.23 cm³ (simulation) and 0.17 ± 0.05 cm³ (experiment) once the applied power was linearly reduced from 3.5 W to 0.2 W in 50 s ("3.5 W fast slope" laser modulation mode). The proposed model may be a useful tool to predict thermal responses of the tissue during LTC.