Stereotactic laser interstitial thermal therapy for the treatment of pediatric drug-resistant epilepsy: indications, techniques, and safety

A Standardized Approach to MRI-Guided Stereotactic Laser Corpus Callosotomy: Technical Description and Pediatric Case Series

BACKGROUND AND OBJECTIVES

Corpus callosotomy is an effective procedure approach for treating medication-resistant drop seizures, which pose a significant challenge in patients with epilepsy. Laser interstitial thermal therapy offers an alternative to open surgery for performing corpus callosotomy that may limit approach-related comorbidities. Practices vary regarding the number of laser filaments used and staging; outcome data for pediatric patients remain relatively limited.

METHODS

We illustrate a set of 4 standardized trajectories for performing MRI-guided stereotactic laser corpus callosotomy (SLCC). For this retrospective cohort study in a pediatric neurosurgery practice, the medical records and imaging were reviewed for 10 consecutive patients who had medication-refractory drop seizures and underwent SLCC. Data collected and analyzed included patient and epilepsy characteristics, procedural details, surgical approaches, and clinical follow-up results.

RESULTS

Over 2 years, complete, single-stage SLCC was performed in 8 patients, and posterior completion SLCC was performed in 2 patients who had previously had open anterior corpus callosotomy. Four laser fibers were used in four-eighth complete SLCC, and 3 fibers were used in four-eighth complete SLCC. Seven of 10 patients were discharged from the hospital on postoperative day 1, with only 1 requiring a maximum stay of 6 days. Five of 9 evaluable patients reported no drop seizures at the last clinical follow-up. In the other 4 patients, 1 experienced them only rarely, another experienced less than 25% preoperative frequency, and the remaining 2 had less than a 50% improvement. In addition, improvement in other seizure types exceeded 50% in 8 of 9 patients. Notably, no perioperative or postoperative complications were observed, nor were there any sustained neurological deficits reported.

CONCLUSION

Complete SLCC can be safely and effectively performed in pediatric patients. It is comparable in effectiveness with open surgery but has lower complication rates and shorter hospitalization.

Complications following laser interstitial thermal therapy: a review

Laser interstitial thermal therapy (LITT) is being performed more frequently for various lesions within neurosurgery, including epileptic foci, vascular malformations, and tumors. Though this technique generally has an excellent safety profile, it is important to be aware of potential complications. Thermal ablation of tissue leads to disruption of the blood brain barrier as well as an inflammatory response both of which cause the majority of complications from LITT. The most common complications of LITT include cerebral edema, focal neurologic deficits, and intracranial hemorrhage. Few studies have identified factors predicting development of these complications, but many of these are transient and resolve without intervention. Modifications to LITT technique that allows better visualization of patient anatomy along the tract, such as fusing vascular imaging with intraoperative MRI, reduce the risk of complications.

Applications of magnetic resonance-guided laser interstitial thermal therapy in disconnective epilepsy surgery

Minimally invasive surgical techniques, such as MR-guided laser interstitial thermal therapy (LITT), have emerged as promising alternatives to open disconnective surgeries in drug-resistant epilepsy (DRE). This review synthesizes current literature on the application of LITT for corpus callosal disconnection and functional hemispheric disconnection. Studies highlight LITT's effectiveness for achieving seizure control and functional outcomes, often with reduced complications compared to traditional open procedures. Challenges include technical limitations to achieving total disconnection and adequate assessment of disconnection postoperatively. The literature is largely composed of observational studies and there is a need for rigorous, multi-center trials to establish robust guidelines and improve generalizability in clinical practice. There is also a need for a more robust exploration of how patient-specific factors contribute to response or nonresponse to intervention.

Magnetic resonance-guided laser interstitial thermal therapy versus open surgical corpus callosotomy for pediatric refractory epilepsy: A systematic review and meta-analysis

PURPOSE

Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a novel, minimally invasive alternative to traditional open surgery corpus callosotomy (CC). We aim to compare both approaches in terms of time of hospitalization and surgical procedure, complications, and efficacy outcomes.

METHODS

A systematic search on PubMed, Embase, Web of Science, and Cochrane Library databases was performed for studies directly comparing MRgLITT and open surgery for refractory epilepsy in children.

RESULTS

A total of 240 patients from five studies were included. There was no statistically significant difference observed between the two groups regarding the favorable Engel outcome. (RR 0.89; 95 % CI 0.70-1.14; p = 0.36; I2=0 %) The mean hospital length of stay (LOS) was significantly shorter in the patients who underwent MRgLITT. (MD -2.84 days; 95 % CI [-3.17]-[-2.51] days; p < 0.00001; I2=90 %) The mean operation duration was significantly longer in the intervention group. (MD 1.38 h; 95 % CI 0.64- 2.12 h; p = 0.00002; I2=55 %). The mean blood loss was significantly lower in patients who underwent MRgLITT. (MD -75.15 ml; 95 % CI [-92.82]-[-57.48] ml; p < 0.00001; I2=0 %) CONCLUSION: CC is a valuable option for treating RE, especially in children. The open surgery bears the stigma of an invasive and complicated technique which might justify its underuse. MRgLITT is a great alternative and possibly a way to widen the use of callosotomy in children, however, its cost and availability may be a challenge.

Current role of magnetic resonance imaging on assessing and monitoring the efficacy of phototherapy

Phototherapy, also known as photobiological therapy, is a non-invasive and highly effective physical treatment method. Its broad use in clinics has led to significant therapeutic results. Phototherapy parameters, such as intensity, wavelength, and duration, can be adjusted to create specific therapeutic effects for various medical conditions. Meanwhile, Magnetic Resonance Imaging (MRI), with its diverse imaging sequences and excellent soft-tissue contrast, provides a valuable tool to understand the therapeutic effects and mechanisms of phototherapy. This review explores the clinical applications of commonly used phototherapy techniques, gives a brief overview of how phototherapy impacts different diseases, and examines MRI's role in various phototherapeutic scenarios. We argue that MRI is crucial for precise targeting, treatment monitoring, and prognosis assessment in phototherapy. Future research and applications will focus on personalized diagnosis and monitoring of phototherapy, expanding its applications in treatment and exploring multimodal imaging technology to enhance diagnostic and therapeutic precision and effectiveness.

A pediatrician's guide to epilepsy surgery

Surgical intervention for epilepsy emerged in the second half of the 20th century as an important option for pediatric patients with medically refractory epilepsy. Both the number of patients undergoing epilepsy surgery and the available surgical procedures for epilepsy have expanded in the last 3 decades, and now range from surgical resection to neuromodulatory device placement1,2 Studies showing that many patients who would be excellent candidates for surgery are still not being offered appropriate interventions have prompted an interest in ensuring that all providers who see patients with epilepsy are aware of the options for epilepsy surgery to facilitate earlier referrals when medications have not been effective3 In this article, we will introduce the pediatrician to the process involved in determining epilepsy surgery candidacy and to surgical outcomes, with the goal of empowering pediatric providers to refer their medically refractory epilepsy patients to a pediatric epilepsy center.

The changing landscape of palliative epilepsy surgery for Lennox Gastaut Syndrome

Lennox Gastaut Syndrome (LGS) is characterized by drug-resistant epilepsy that typically leads to decreased quality of life and deleterious neurodevelopmental comorbidities from medically refractory seizures. In recent years there has been a dramatic increase in the development and availability of novel treatment strategies for Lennox Gastaut Syndrome patient to improve seizure. Recent advances in neuromodulation and minimally invasive magnetic resonance guided laser interstitial thermal therapy (MRgLITT) have paved the way for new treatments strategies including deep brain stimulation (DBS), responsive neurostimulation (RNS), and MRgLITT corpus callosum ablation. These new strategies offer hope for children with drug-resistant generalized epilepsies, but important questions remain about the safety and effectiveness of these new approaches. In this review, we describe the opportunities presented by these new strategies and how each treatment strategy is currently being employed. Next, we will critically assess available evidence for these new approaches compared to traditional palliative epilepsy surgery approaches, such as vagus nerve stimulation (VNS) and open microsurgical corpus callosotomy (CC). Finally, we will describe future directions that would help define which of the available strategies should be employed and when.

Technical Note: Advantages of a 2-Room Intraoperative 3-Tesla Magnetic Resonance Imaging Operating Suite for Performing Laser Interstitial Thermal Therapy in Pediatric Epilepsy and Tumor Surgery

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

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.

Arduino based intra-cerebral microinjector device for neuroscience research

Stereotaxic surgery is a less invasive form of surgery that uses a three-dimensional coordinate system to place instruments at a specific location in the brain. Through this type of surgery, one can place needles among other tools within the structures of the brain. Therefore, injections can be given in order to deliver substances that cannot cross the blood-brain barrier. The two most important parameters of the microinjection to control are volume and speed. The volume should not be so large that it displaces the brain tissue and tears it. The injection speed must also be slow so that the liquid that comes out of the syringe can diffuse into the tissue without displacing it and damaging it. Thus, the objectives of the present work are: 1) To develop not a 3D printed prototype but an end-user device. 2) The device must be for animal research only. 3) It must have the same precision in volume and speed as commercial devices. 4) It must be adjustable for microsyringes from 0.5 µl to 1 ml. 5) It must be possible to place it directly on the stereotaxic surgery apparatus and to use it separately. 6) The price must be substantially lower than that of the commercial devices.

Surgical outcomes of open and laser interstitial thermal therapy approaches for corpus callosotomy in pediatric epilepsy

OBJECTIVE

Corpus callosotomy (CC) is a palliative surgical intervention for patients with medically refractory epilepsy that has evolved in recent years to include a less-invasive alternative with the use of laser interstitial thermal therapy (LITT). LITT works by heating a stereotactically placed laser fiber to ablative temperatures under real-time magnetic resonance imaging (MRI) thermometry. This study aims to (1) describe the surgical outcomes of CC in a large cohort of children with medically refractory epilepsy, (2) compare anterior and complete CC, and (3) review LITT as a surgical alternative to open craniotomy for CC.

METHODS

This retrospective cohort study included 103 patients <21 years of age with at least 1 year follow-up at a single institution between 2003 and 2021. Surgical outcomes and the comparative effectiveness of anterior vs complete and open versus LITT surgical approaches were assessed.

RESULTS

CC was the most common surgical disconnection (65%, n = 67) followed by anterior two-thirds (35%, n = 36), with a portion proceeding to posterior completion (28%, n = 10). The overall surgical complication rate was 6% (n = 6/103). Open craniotomy was the most common approach (87%, n = 90), with LITT used increasingly in recent years (13%, n = 13). Compared to open, LITT had shorter hospital stay (3 days [interquartile range (IQR) 2-5] vs 5 days [IQR 3-7]; p < .05). Modified Engel class I, II, III, and IV outcomes at last follow-up were 19.8% (n = 17/86), 19.8% (n = 17/86), 40.2% (n = 35/86), and 19.8% (n = 17/86). Of the 70 patients with preoperative drop seizures, 75% resolved postoperatively (n = 52/69).

SIGNIFICANCE

No significant differences in seizure outcome between patients who underwent only anterior CC and complete CC were observed. LITT is a less-invasive surgical alternative to open craniotomy for CC, associated with similar seizure outcomes, lower blood loss, shorter hospital stays, and lower complication rates, but with longer operative times, when compared with the open craniotomy approach.

Posterior Fossa Laser Interstitial Thermal Therapy in Children

Real-time, MRI-guided laser interstitial thermal therapy (MRgLITT) is emerging as a minimally invasive technique for epilepsy surgery and for deep-seated tumors in the pediatric population. However, MRgLITT for posterior fossa lesions poses a unique challenge that is especially evident in this age range and remains understudied. In this study, we report our experience and analyze the current literature on MRgLITT for the treatment of posterior fossa in children.

Non-pharmacological treatment options of drug-resistant epilepsy in subcortical band heterotopia: systematic review and illustrative case

OBJECTIVE

Subcortical band heterotopia is a rare X-linked neuronal migration disorder primarily in females often associated with drug-resistant epilepsy. The aim of this study is to review the literature for non-pharmacological treatment options of drug-resistant epilepsy in subcortical band heterotopia.

MATERIAL AND METHODS

In accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, we performed a systematic review. Entering the keywords "double cortex," "subcortical band heterotopia," and "subcortical laminar heterotopia," we searched Scopus and PubMed databases. We paid particular attention to type of invasive and non-invasive treatment, radiological presentation, and outcome. We also describe a related case report, managed at Alder Hey Children's Hospital, Liverpool.

RESULTS

The systematic literature review yielded 25 patients with subcortical band heterotopia and drug-resistant epilepsy who underwent non-pharmacological treatment. Including our patient, 26 patients were reported. The patients' mean age at seizure onset was 6.5 years (range 0.2-23) with a female sex predilection (5.25:1). The patients' mean age at invasive or non-invasive treatment was 21.5 years (range 6.5-51). The 26 patients underwent 29 non-pharmacological treatments. Ten patients underwent corpus callosotomy; 8 patients had a formal temporal lobectomy. Three patients had focal cortical resection. Two patients respectively had multiple subpial transections, insertion of a vagal nerve stimulator, or deep brain stimulation of the bilateral anterior nuclei of the thalamus. One patient underwent responsive focal neurostimulation. Another patient had transcutaneous stimulation of the vagal nerve. Sixteen patients reported a reduction or the disappearance of the seizures; 1 patient had no improvement. The outcome of 2 patients was classified class I, of 1 patient class II, of 1 patient class III, and of 5 patients class IV according to the Engel Epilepsy Surgery Outcome Scale.

CONCLUSION

Mainly corpus callosotomy and formal temporal lobectomy have been performed as non-pharmacological treatment with few cases published overall. Several other invasive procedures and one non-invasive technique are based on case reports. The small number of reported cases prevents drawing a firm conclusion as to which non-pharmacological treatment is the best treatment option for refractive epilepsy in patients with subcortical band heterotopia.

Seizure outcome of pediatric magnetic resonance-guided laser interstitial thermal therapy versus open surgery: A matched noninferiority cohort study

OBJECTIVE

Minimally invasive magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) has been proposed as an alternative to open epilepsy surgery, to address concerns regarding the risk of open surgery. Our primary hypothesis was that seizure freedom at 1 year after MRgLITT is noninferior to open surgery in children with drug-resistant epilepsy (DRE). The secondary hypothesis was that MRgLITT has fewer complications and shorter hospitalization than surgery. The primary objective was to compare seizure outcome of MRgLITT to open surgery in children with DRE. The secondary objective was to compare complications and length of hospitalization of the two treatments.

METHODS

This retrospective multicenter cohort study included children with DRE treated with MRgLITT or open surgery with 1-year follow-up. Exclusion criteria were corpus callosotomy, neurostimulation, multilobar or hemispheric surgery, and lesion with maximal dimension > 60 mm. MRgLITT patients were propensity matched to open surgery patients. The primary outcome was seizure freedom at 1 year posttreatment. The difference in seizure freedom was compared using noninferiority test, with noninferiority margin of -10%. The secondary outcomes were complications and length of hospitalization.

RESULTS

One hundred eighty-five MRgLITT patients were matched to 185 open surgery patients. Seizure freedom at 1 year follow-up was observed in 89 of 185 (48.1%) MRgLITT and 114 of 185 (61.6%) open surgery patients (difference = -13.5%, one-sided 97.5% confidence interval = -23.8% to ∞, p_{Noninferiority}  = .79). The lower confidence interval boundary of -23.8% was below the prespecified noninferiority margin of -10%. Overall complications were lower in MRgLITT compared to open surgery (10.8% vs. 29.2%, respectively, p < .001). Hospitalization was shorter for MRgLITT than open surgery (3.1 ± 2.9 vs. 7.2 ± 6.1 days, p < .001).

SIGNIFICANCE

Seizure outcome of MRgLITT at 1 year posttreatment was inferior to open surgery. However, MRgLITT has the advantage of better safety profile and shorter hospitalization. The findings will help counsel children and parents on the benefits and risks of MRgLITT and contribute to informed decision-making on treatment options.

Corpus Callosotomy Is a Safe and Effective Procedure for Medically Resistant Epilepsy

Corpus callosotomy (CC) is an effective surgical treatment for medically resistant generalized or multifocal epilepsy (MRE). The premise of CC extrapolates from the observation that the corpus callosum is the predominant commissural pathway that allows spread and synchroneity of epileptogenic activity between the hemispheres. Candidacy for CC is typically reserved for patients seeking palliative epilepsy treatment with the goal of reducing the frequency of drop attacks, although reduction of other seizure semiologies (absence, complex partial seizures, and tonic-clonic) has been observed. A reduction in morbidity affiliated with evolution of surgical techniques to perform CC has improved the safety profile of the procedure without necessarily sacrificing efficacy.