Magnetic resonance-guided laser interstitial thermal therapy: report of a series of pediatric brain tumors

Exoscope aided trans-sulcal minimally invasive parafascicular resection of a paediatric brainstem pilocytic astrocytoma using a tubular retractor system

The surgical management of brainstem glioma is challenging and has significant morbidity. Advances in surgical armamentarium has presented the opportunity to tackle these lesions. We present the case of a paediatric patient with a 2.3cm midbrain pilocytic astrocytoma. With the aid of tractography, neuro-navigation, 3-dimensional exoscope and a tubular retractor, near total resection of the tumour was achieved through a trans-sulcal para-fascicular approach without permanent injury to the corticospinal tract. To our knowledge this is the first report of a brainstem tumour resected using this approach and demonstrates what can be achieved with synergistic utility of evolving technologies in neurosurgery.

Neoadjuvant Chemotherapy with Laser Interstitial Thermal Therapy in Central Nervous System Neuroblastoma: Illustrative Case and Literature Review

Primitive neuroectodermal tumors of the central nervous system, or CNS neuroblastoma, are rare neoplasms in children. Recently, methylation profiling enabled the discovery of four distinct entities of these tumors. The current treatment paradigm involves surgical resection followed by chemotherapy and radiation. However, upfront surgical resection carries high surgical morbidity in this patient population due to their young age, tumor vascularity, and often deep location in the brain. We report a case of CNS neuroblastoma that can be successfully treated with neoadjuvant chemotherapy followed by minimally invasive laser interstitial thermal therapy and radiation. The patient has complete treatment with no evidence of recurrence at one year follow-up. This case illustrates a potential paradigm shift in the treatment of these rare tumors can be treated using minimally invasive surgical approach to achieve a favorable outcome.

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.

MRI-guided laser interstitial thermal therapy for deep-seated gliomas in children with neurofibromatosis type 1: report of two cases

PURPOSE

Nearly a quarter of neurofibromatosis type 1 (NF 1)- associated diencephalic low-grade tumors are refractory to chemotherapy. Addition of alternative treatment options with laser interstitial thermal therapy will have a positive impact on the outcome of these patients.

METHODS

We report on two illustrated cases of pediatric NF1- associated, chemoresistant, WHO grade 1 pilocytic astrocytomas treated with laser interstitial thermal therapy (LITT).

RESULTS

Both tumors responded favorably to LITT.

CONCLUSION

LITT should be considered as a treatment option for chemoresistant deep-seated NF1-associated low-grade gliomas.

Laser Interstitial Thermal Therapy for the Treatment of Primary and Metastatic Brain Tumors: A Systematic Review and Meta-Analysis

BACKGROUND

Laser interstitial thermal therapy (LITT) is a minimally invasive treatment option for intracranial tumors that are challenging to treat via traditional methods; however, its safety and efficacy are not yet well validated in the literature. The objectives of the study were to assess the available evidence of the indications and adverse events (AEs) of LITT and 1-year progression-free survival and 1-year overall survival in the treatment of primary and secondary brain tumors.

METHODS

A comprehensive literature search was conducted through the databases PubMed, Embase, and the Cochrane Library until October 2021. Comparative and descriptive studies, except for case reports, were included in the meta-analysis. Separate analyses by tumor type (high-grade gliomas, including World Health Organization grade 4 astrocytomas [which include glioblastomas] as a specific subgroup; low-grade gliomas; and brain metastases) were conducted. Pooled effect sizes and their 95% confidence intervals (CI) were generated via random-effects models.

RESULTS

Forty-five studies met the inclusion criteria, yielding 826 patients for meta-analysis. There were 829 lesions in total, of which 361 were classified as high-grade gliomas, 116 as low-grade gliomas, 337 as metastatic brain tumors, and 15 as nonglial tumors. Indications for offering LITT included deep/inaccessible tumor (12 studies), salvage therapy after failed radiosurgery (9), failures of ≥2 treatment options (3), in pediatric patients (4), patient preference (1); indications were nonspecific in 12 studies. Pooled incidence of all (minor or major) procedure-related AEs was 30% (95% CI, 27%-40%) for all tumors. Pooled incidence of neurologic deficits (minor or major) was 16% (12%-22%); postprocedural edema 14% (8%-22%); seizure 6% (4%-9%); hematoma 20% (14%-29%); deep vein thrombosis 19% (11%-30%); hydrocephalus 8% (5%-12%); and wound infection 5% (3%-7%). One-year progression-free survival was 18.6% (11.3%-29.0%) in high-grade gliomas, 16.9% (11.6%-24.0%) among the grade 4 astrocytomas; and 51.2% (36.7%-65.5%) in brain metastases. One-year overall survival was 43.0% (36.0%-50.0%) in high-grade glioma, 45.9% (95% CI, 37.9%-54%) in grade 4 astrocytomas; 93.0% (42.3%-100%) in low-grade gliomas, and 56.3% (47.0%-65.3%) in brain metastases.

CONCLUSIONS

New neurologic deficits and postprocedural edema were the most reported AEs after LITT, albeit mostly transient. This meta-analysis provides the best statistical estimates of progression and survival outcomes based on the available information. LITT is generally a safe procedure for selected patients, and future well-designed comparative studies on its outcomes versus the current standard of care should be performed.

The use of stereotactic MRI-guided laser interstitial thermal therapy for the treatment of pediatric cavernous malformations: the SUNY Upstate Golisano Children's Hospital experience

PURPOSE

Cavernous malformations (CM) are central nervous system lesions characterized by interlaced vascular sinusoids coated with endothelial cells without intervening parenchyma. Magnetic resonance imaging-guided laser interstitial thermal therapy (MRIgLITT) is a minimally invasive treatment modality that can precisely treat pathologic cerebral tissue, making it an effective alternative for the management of cavernomas. We describe the outcomes of a series of pediatric patients with cavernous brain malformations treated with MRIgLITT between 2014 and 2018 at our institution.

METHODS

We retrospectively analyzed 11 cavernomas in 6 pediatric patients treated with MRIgLITT. Both the Visualase System^® and/or Neuroblate^® systems were used. A variation of the surgical technique on the application of the laser was developed. Post-ablation MRIs were obtained to assess ablated areas.

RESULTS

A total of 11 cavernomas in 6 patients were treated with MRIgLITT. Median age was 15 years (12 to 17 years); 75% were males. Presenting symptoms were headache (75%) and seizures (25%). Two patients presented with multiple CMs. All lesions in this study were supratentorial (cerebral hemispheres 81.8%, corpus callosum 9.1%, basal ganglia 9.1%). Our surgical technique was well-tolerated, with no significant adverse events observed. Hospital stay for all patients was less than 48 hours.

CONCLUSION

MRIgLITT is an effective minimally invasive technique for the treatment of pediatric CMs. It represents a useful and safe tool, when other therapeutic alternatives may represent a greater risk of surgical morbidity.

Laser interstitial thermal therapy (LITT) for pediatric patients affected by intracranial tumors

Introduction

The surgical treatment of brain tumors has evolved over time, offering different strategies tailored to patients and their specific lesions. Among these strategies, Laser Interstitial Thermal Therapy (LITT) is one of the most recent advances in pediatric neurooncological surgery, and its results and evolution are still under assessment.

Methods

We retrospectively analyzed data from six pediatric patients with deep-seated brain tumors treated with LITT at a single center between November 2019 and June 2022. A total of four patients underwent a stereotaxic biopsy during the same operating session. The indications and preparation for LITT, technical issues, clinical and radiological follow-up, impact on quality of life, and oncological treatment are discussed.

Results

The mean patient age eight years (ranging from 2 to 11 years). The lesion was thalamic in four patients, thalamo-peduncular in one, and occipital posterior periventricular in one. In total, two patients had been previously diagnosed with low-grade glioma (LGG). Biopsies revealed LGG in two patients, ganglioglioma grade I in one, and diffuse high-grade glioma (HGG) in one. Postoperatively, two patients presented with transient motor deficits. The mean follow-up period was 17 months (ranging from 5 to 32 months). Radiological follow-up showed a progressive reduction of the tumor in patients with LGG.

Conclusion

Laser interstitial thermal therapy is a promising, minimally invasive treatment for deep-seated tumors in children. The results of lesion reduction appear to be relevant in LGGs and continue over time. It can be used as an alternative treatment for tumors located at sites that are difficult to access surgically or where other standard treatment options have failed.

Magnetic Resonance-Guided Laser Interstitial Thermal Therapy for Management of Low-Grade Gliomas and Radiation Necrosis: A Single-Institution Case Series

BACKGROUND

Laser interstitial thermal therapy (LITT) has emerged as a minimally invasive treatment modality for ablation of low-grade glioma (LGG) and radiation necrosis (RN).

OBJECTIVE

To evaluate the efficacy, safety, and survival outcomes of patients with radiographically presumed recurrent or newly diagnosed LGG and RN treated with LITT.

METHODS

The neuro-oncological database of a quaternary center was reviewed for all patients who underwent LITT for management of LGG between 1 January 2013 and 31 December 2020. Clinical data including demographics, lesion characteristics, and clinical and radiographic outcomes were collected. Kaplan-Meier analyses comprised overall survival (OS) and progression-free survival (PFS).

RESULTS

Nine patients (7 men, 2 women; mean [SD] age 50 [16] years) were included. Patients underwent LITT at a mean (SD) of 11.6 (8.5) years after diagnosis. Two (22%) patients had new lesions on radiographic imaging without prior treatment. In the other 7 patients, all (78%) had surgical resection, 6 (67%) had intensity-modulated radiation therapy and chemotherapy, respectively, and 4 (44%) had stereotactic radiosurgery. Two (22%) patients had lesions that were wild-type IDH1 status. Volumetric assessment of preoperative T1-weighted contrast-enhancing and T2-weighted fluid-attenuated inversion recovery (FLAIR) sequences yielded mean (SD) lesion volumes of 4.1 (6.5) cm³ and 26.7 (27.9) cm³, respectively. Three (33%) patients had evidence of radiographic progression after LITT. The pooled median (IQR) PFS for the cohort was 52 (56) months, median (IQR) OS after diagnosis was 183 (72) months, and median (IQR) OS after LITT was 52 (60) months. At the time of the study, 2 (22%) patients were deceased.

CONCLUSIONS

LITT is a safe and effective treatment option for management of LGG and RN, however, there may be increased risk of permanent complications with treatment of deep-seated subcortical lesions.

Interstitial Photothermal Therapy Generates Durable Treatment Responses in Neuroblastoma

Photothermal therapy (PTT) represents a promising modality for tumor control typically using infrared light-responsive nanoparticles illuminated by a wavelength-matched external laser. However, due to the constraints of light penetration, PTT is generally restricted to superficially accessible tumors. With the goal of extending the benefits of PTT to all tumor settings, interstitial PTT (I-PTT) is evaluated by the photothermal activation of intratumorally administered Prussian blue nanoparticles with a laser fiber positioned interstitially within the tumor. This interstitial fiber, which is fitted with a terminal diffuser, distributes light within the tumor microenvironment from the "inside-out" as compared to from the "outside-in" traditionally observed during superficially administered PTT (S-PTT). I-PTT improves the heating efficiency and heat distribution within a target treatment area compared to S-PTT. Additionally, I-PTT generates increased cytotoxicity and thermal damage at equivalent thermal doses, and elicits immunogenic cell death at lower thermal doses in targeted neuroblastoma tumor cells compared to S-PTT. In vivo, I-PTT induces significantly higher long-term tumor regression, lower rates of tumor recurrence, and improved long-term survival in multiple syngeneic murine models of neuroblastoma. This study highlights the significantly enhanced therapeutic benefit of I-PTT compared to traditional S-PTT as a promising treatment modality for solid tumors.

Symptomatic bilateral choroid plexus xanthogranuloma in a pediatric patient

INTRODUCTION

Central nervous system xanthogranulomas are uncommon clinical entities, and symptomatic bilateral choroid plexus xanthogranulomas are rare.

CASE PRESENTATION

We present the case of a 15-year-old male patient with bilateral choroid plexus xanthogranulomas with symptoms of increased intracranial pressure. Gross total resection of the tumor in the left lateral ventricle was performed. The patient improved, and asymptomatic right-sided tumor was monitored at follow-up.

CONCLUSION

The main treatment objective in these tumors is gross total resection. Asymptomatic tumors can be followed without intervention. However, surgery should be performed for symptomatic tumors that cause hydrocephalus or symptoms of increased intracranial pressure.

Treatment of a symptomatic thalamic pilocytic astrocytoma with reservoir placement and laser interstitial thermal therapy: illustrative case

BACKGROUND

Treatment of pilocytic astrocytomas (PAs) in children can be challenging when they arise in deep midline structures because complete surgical resection may result in significant neurological injury. Laser interstitial thermal therapy (LITT) has provided an alternative treatment modality for lesions that may not be amenable to resection. However, many patients with PAs may be symptomatic from a compressive cyst associated with the PA, and LITT does not obviate the need for cystic decompression in these patients.

OBSERVATIONS

A 12-year-old male presented with left-sided weakness. Magnetic resonance imaging (MRI) revealed an enhancing mass with a large cyst involving the right thalamus and basal ganglia. The patient underwent a reservoir placement for cyst drainage and biopsy of the mass, revealing a pilocytic astrocytoma. He then underwent LITT followed by adjuvant chemotherapy. Sixteen months after LITT, follow-up MRI of the brain revealed no tumor growth.

LESSONS

This is the first case to describe reservoir placement to treat the cystic portion of a pilocytic astrocytoma followed by LITT and targeted chemotherapy. Reservoir placement reduced the cyst’s mass effect and resolved the patient’s symptoms, allowing for treatment options beyond resection.

Magnetic Resonance-guided Laser Interstitial Thermal Therapy (MRgLITT) for Brainstem Pathologies

OBJECTIVE

Magnetic Resonance-guided Laser interstitial thermal therapy (MRgLITT) is a minimally invasive and effective treatment option that can potentially treat deep-seated pathologies in cases where there are no safe open surgical corridors. In this report, we present our experience using MRgLITT for brainstem pathologies.

METHODS

A retrospective chart analysis was conducted of all patients who underwent MRgLITT for pathologies within or closely surrounding the brainstem between 2011 and 2020. The patients underwent stereotactic laser placement in the operating suite and were transported to the MRI suite for laser ablation with real-time monitoring. Demographics, operative parameters and complications were recorded.

RESULTS

A total of twelve patients underwent MRgLITT for brainstem pathologies. The average age of the patients was 47.6 years old, ranging from 4 to 75. Pathologies included both primary and metastatic intracranial tumors. The average pre-ablation volume of the targets was 2.4cm³ ±SEM=0.50. The average time of ablation was 324.3± 60.7 seconds and average post-ablation volume was 2.92±0.53 cm³. There was one perioperative mortality directly related to the procedure and seven cases of post-operative deficits. Two patients had recurrence after MRgLITT and opted to undergo additional alternative treatments.

CONCLUSION

The brainstem represents formidable territory even for minimally invasive procedures. The overall morbidity and mortality remains high, and the probability of achieving a meaningful outcome needs to be carefully assessed.

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.

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.

Laser thermal therapy in the management of high-grade gliomas

Laser interstitial thermal therapy (LITT) is a minimally invasive therapy that have been used for brain tumors, epilepsy, chronic pain, and other spine pathologies. This therapy is performed under imaging and stereotactic guidance to precisely direct the probe and ablate the area of interest using real-time magnetic resonance (MR) thermography. LITT has gained popularity as a treatment for glioma because of its minimally invasive nature, small skin incision, repeatability, shorter hospital stay, and the possibility of receiving adjuvant therapy shortly after surgery instead of several weeks as required after open surgical resection. Several reports have demonstrated the usefulness of LITT in the treatment of newly-diagnosed and recurrent gliomas. In this review, we will summarize the recent evidence of this therapy in the field of glioma surgery and the future perspectives of the use of LITT combined with other treatment strategies for this devastating disease.

Clinical and Neuroimaging Features of Magnetic Resonance-Guided Stereotactic Laser Ablation for Newly Diagnosed and Recurrent Pediatric Brain Tumors: A Single Institutional Series

OBJECTIVE

We describe our single-institutional experience with magnetic resonance-guided stereotactic laser ablation (SLA) for the treatment of newly diagnosed and recurrent pediatric brain tumors.

METHODS

Eighteen consecutive ablation procedures were performed in 17 patients from March 2016-April 2020. Patient demographics, indications, procedures, neuroimaging features, and outcomes were reviewed retrospectively.

RESULTS

Seventeen patients (mean age of 11.4 years, 11 boys, 6 girls) underwent SLA with a mean follow-up of 24 months (range: 3-45 months). Tumor histologies included pilocytic astrocytoma (n = 5), ganglioglioma (n = 3), low-grade glioma not otherwise specified (n = 4), glioblastoma (n = 2), meningioma (n = 1), medulloblastoma (n = 1), and metastatic malignant peripheral nerve sheath tumor (n = 1). SLA was first-line therapy in 10 patients. Mean procedure duration including anesthesia time was 328 minutes (range: 244-529 minutes), and mean postoperative length of stay was 1.5 days (range 1-5 days). The complication rate was 29%, which included 3 patients who experienced postoperative motor changes, which resolved within several weeks of surgery, 1 patient with self-limited intraoperative bradycardia and hypotension, and 1 patient who died postoperatively due to intracranial hemorrhage from a distant lesion. Twelve of 17 patients had a neuroimaging response after SLA (4 complete responses, 8 partial responses, 1 stable disease). Percentage of tumor shrinkage from baseline ranged from 33%-100% (mean 75%). Patients with low-grade glioma exhibited the best responses to SLA (range 3%-100% decrease; mean 90%; 36% complete response rate).

CONCLUSIONS

SLA is a minimally invasive modality for the treatment of newly diagnosed and recurrent low-grade pediatric brain tumors. Low-grade glioma exhibited the best responses. Identification of ideal candidates for SLA, mitigation of perioperative complications, and demonstration of long-term outcomes need to be better defined in a clinical trial setting.

Laser interstitial thermal therapy for pediatric atypical teratoid/rhabdoid tumor: case report

Herein, the authors describe the successful use of laser interstitial thermal therapy (LITT) for management of metastatic craniospinal disease for biopsy-proven atypical teratoid/rhabdoid tumor in a 16-month-old boy presenting to their care. Specifically, LITT was administered to lesions of the right insula and left caudate. The patient tolerated 2 stages of LITT to the aforementioned lesions without complication and with evidence of radiographic improvement of lesions at the 2- and 6-month follow-up appointments. To the authors' knowledge, this represents the first such published report of LITT for management of atypical teratoid/rhabdoid tumor.

Laser interstitial thermotherapy (LITT) for the treatment of tumors of the brain and spine: a brief review

Introduction

Laser Interstitial Thermotherapy (LITT; also known as Stereotactic Laser Ablation or SLA), is a minimally invasive treatment modality that has recently gained prominence in the treatment of malignant primary and metastatic brain tumors and radiation necrosis and studies for treatment of spinal metastasis has recently been reported.

Methods

Here we provide a brief literature review of the various contemporary uses for LITT and their reported outcomes.

Results

Historically, the primary indication for LITT has been for the treatment of recurrent glioblastoma (GBM). However, indications have continued to expand and now include gliomas of different grades, brain metastasis (BM), radiation necrosis (RN), other types of brain tumors as well as spine metastasis. LITT is emerging as a safe, reliable, minimally invasive clinical approach, particularly for deep seated, focal malignant brain tumors and radiation necrosis. The role of LITT for treatment of other types of tumors of the brain and for spine tumors appears to be evolving at a small number of centers. While the technology appears to be safe and increasingly utilized, there have been few prospective clinical trials and most published studies combine different pathologies in the same report.

Conclusion

Well-designed prospective trials will be required to firmly establish the role of LITT in the treatment of lesions of the brain and spine.

The Understanding of Pediatric Akinetic Mutism

Pediatric akinetic mutism syndrome is a clinical disease resulting from cerebellar injury and characterized by the absence of speech or reduced speech, emotional lability, there may also be hypotonia, oropharyngeal dysfunction/dysphagia, bladder and intestinal incontinence, or other behavioral disorders and neurological signals. It is described as the most recurrent complication in children, after posterior fossa tumor surgery, mainly related to cerebellar midline injuries. An increasing number of research and prospective reviews have provided valuable information on cerebellar mutism syndrome in recent years. The purpose of this review was to elucidate the pathophysiological basis and the predictive factors for this syndrome. Most cases of mutism are due to injury cerebellar tracts and cerebellar-cerebral circuits, involving particularly distinct points of the dentate-thalamus-cortical and dentato-rubro-thalamus-cortical. Advanced neuroimaging techniques, such as tractography and perfusion studies, have contributed to demonstrating changes in these pathways in patients with pediatric cerebellar mutism.

Current Role of Laser Interstitial Thermal Therapy in the Treatment of Intracranial Tumors

Laser interstitial thermal therapy (LITT) is gaining popularity in the treatment of both primary and secondary intracranial tumors. The goal of LITT is to deliver thermal energy in a predictable, controlled, and minimally invasive fashion. It can be particularly valuable in patients with recurrent tumors who, due to previous radiation or surgery, may have a potentially higher risk of wound breakdown or infection with repeat craniotomy. Deep-seated lesions that are often inaccessible through open approaches (thalamus, hypothalamus, mesial basal temporal lobe, brainstem) may also be suitable targets. The experience and data published thus far on this modality is limited but growing. This review highlights the use of LITT as a primary treatment method in a variety of intracranial tumors, as well as its application as an adjunct to established surgical techniques.

Awake Laser Ablation for Patients With Tumors in Eloquent Brain Areas: Operative Technique and Case Series

Background Magnetic resonance imaging (MRI)-guided laser interstitial thermal therapy (LITT) is a minimally invasive treatment modality that has been gaining traction in neuro-oncology. Laser ablation is a particularly appealing treatment option when eloquent neurologic function at the tumor location precludes conventional surgical excision. Although typically performed under general anesthesia, LITT in awake patients may help monitor and preserve critical neurologic functions. Objective To describe intraoperative workflow and clinical outcomes in patients undergoing awake laser ablation of brain tumors. Methods We present a cohort of six patients with tumors located in eloquent brain areas that were treated with awake LITT and report three different workflow paradigms involving diagnostic or intraoperative MRI. In all cases, we used NeuroBlate® (Monteris Medical, Plymouth, MN) fiberoptic laser probes for stereotactic laser ablation of tumors. The neurologic status of patients was intermittently assessed every few minutes during the ablation. Results The mean preoperative tumor volume that was targeted was 12.09 ± 3.20 cm³, and the estimated ablation volume was 12.06 ± 2.75 cm³. Performing the procedure in awake patients allowed us close monitoring of neurologic function intraoperatively. There were no surgical complications. The length of stay was one day for all patients except one. Three patients experienced acute or delayed worsening of pre-existing neurologic deficits that responded to corticosteroids. Conclusion We propose that awake LITT is a safe approach when tumors in eloquent brain areas are considered for laser ablation.

Stereotactic laser ablation for subependymal giant cell astrocytomas: personal experience and review of the literature

PURPOSE

Subependymal giant cell astrocytomas (SEGAs) are rare tumors typically found in tuberous sclerosis patients. They typically grow in the region of the foramen of Monro and can occlude it, leading to hydrocephalus. Currently, gross total resection is the standard of care, with low rates of recurrence but high rates of complication, especially with larger lesions. Laser interstitial thermal therapy (LITT) is a newly emerging treatment modality for a variety of pathologies. Here, we present a case series of SEGAs managed via LITT and endoscopic, stereotactic septostomy.

METHODS

A retrospective chart review was performed to identify three cases in which SEGAs were treated via LITT and septostomy. Stereotactic ablation was performed via magnetic resonance (MR) thermometry with laser output set to 69% for 2.5 min, with post-ablation scans for visualization of treatment area.

RESULTS

Average age at surgery was 8.2 years. Pre-operative tumor volumes were 0.43, 1.51, and 3.88 cm³. Post-operative tumor volumes were 0.25, 0.21, and 0.68 cm³. Mean tumor volume reduction was 70%. No complications occurred.

CONCLUSION

LITT with septostomy should be considered a viable primary or adjunct treatment modality for SEGAs.

Magnetic resonance-guided laser interstitial thermal therapy for posterior fossa neoplasms

PURPOSE

Magnetic resonance-guided laser interstitial thermal therapy (LITT) has been increasingly used to treat a number of intracranial pathologies, though its use in the posterior fossa has been limited to a few small series. We performed a multi-institutional review of targets in the posterior fossa, reporting the efficacy and safety profile associated with laser ablation in this region of the brain.

METHODS

A retrospective review of patients undergoing LITT in the posterior fossa was performed from August 2010 to March 2020. Patient demographic information was collected alongside the operative parameters and patient outcomes. Reported outcomes included local control of the lesion, postoperative complications, hospital length of stay, and steroid requirements.

RESULTS

58 patients across four institutions underwent LITT in the posterior fossa for 60 tumors. The median pre-ablation tumor volume was 2.24 cm³. 48 patients (50 tumors) were available for follow-up. An 84% (42/50) overall local control rate was achieved at 9.5 months median follow up. There were two procedural complications, including insertional hemorrhage and laser misplacement and 12/58 (21%) patients developed new neurological deficits. There was one procedure related death. The median length of hospital stay was 1 day, with 20.7% of patients requiring discharge to a rehabilitation facility.

CONCLUSIONS

LITT is an effective approach for treating pathology in the posterior fossa. The average target size is smaller than what has been reported in the supratentorial space. Care must be taken to prevent injury to surrounding structures given the close proximity of critical structures in this region.

The intersection between immunotherapy and laser interstitial thermal therapy: a multipronged future of neuro-oncology

The rise of immunotherapy (IT) in oncological treatment has greatly improved outcomes in a number of disease states. However, its use in tumors of the central nervous system (CNS) remains limited for multiple reasons related to the unique immunologic tumor microenvironment. As such, it is valuable to consider the intersection of IT with additional treatment methods that may improve access to the CNS and effectiveness of existing IT modalities. One such combination is the pairing of IT with localized hyperthermia (HT) generated through technologies such as laser interstitial thermal therapy (LITT). The wide-ranging immunomodulatory effects of localized and whole-body HT have been investigated for some time. Hyperthermia has demonstrated immunostimulatory effects at the level of tumor cells, immune cells, and the broader environment governing potential immune surveillance. A thorough understanding of these effects as well as the current and upcoming investigations of such in combination with IT is important in considering the future directions of neuro-oncology.

Hyperthermia treatment advances for brain tumors

Hyperthermia therapy (HT) of cancer is a well-known treatment approach. With the advent of new technologies, HT approaches are now important for the treatment of brain tumors. We review current clinical applications of HT in neuro-oncology and ongoing preclinical research aiming to advance HT approaches to clinical practice. Laser interstitial thermal therapy (LITT) is currently the most widely utilized thermal ablation approach in clinical practice mainly for the treatment of recurrent or deep-seated tumors in the brain. Magnetic hyperthermia therapy (MHT), which relies on the use of magnetic nanoparticles (MNPs) and alternating magnetic fields (AMFs), is a new quite promising HT treatment approach for brain tumors. Initial MHT clinical studies in combination with fractionated radiation therapy (RT) in patients have been completed in Europe with encouraging results. Another combination treatment with HT that warrants further investigation is immunotherapy. HT approaches for brain tumors will continue to a play an important role in neuro-oncology.

Retrospective Multicentric Study on Non-Optic CNS Tumors in Children and Adolescents with Neurofibromatosis Type 1

s: The natural history of non-optic central nervous system (CNS) tumors in neurofibromatosis type 1 (NF1) is largely unknown. Here, we describe prevalence, clinical presentation, treatment, and outcome of 49 non-optic CNS tumors observed in 35 pediatric patients (0-18 years). Patient- and tumor-related data were recorded. Overall survival (OS) and progression-free survival (PFS) were evaluated. Eighteen patients (51%) harbored an optic pathway glioma (OPG) and eight (23%) had multiple non-optic CNS lesions. The majority of lesions (37/49) were managed with a wait-and-see strategy, with one regression and five reductions observed. Twenty-one lesions (42.9%) required surgical treatment. Five-year OS was 85.3%. Twenty-four patients progressed with a 5-year PFS of 41.4%. Patients with multiple low-grade gliomas progressed earlier and had a lower 5-year PFS than those with one lesion only (14.3% vs. 57.9%), irrespective of OPG co-presence. Non-optic CNS tumors are common in young patients with NF1. Neither age and symptoms at diagnosis nor tumor location influenced time to progression in our series. Patients with multiple lesions tended to have a lower age at onset and to progress earlier, but with a good OS.

Seizure freedom from recurrent insular low-grade glioma following laser interstitial thermal therapy

Pediatric low-grade gliomas (LGGs) are found in approximately 1-3% of patients with childhood epilepsy that is often medically refractory. Magnetic resonance guided laser interstitial thermal therapy (MRgLITT) is a minimal access technique FDA-approved since 2007 to ablate soft tissue lesions including brain tumors and seizure foci in children. The authors describe the case of an 11-year-old boy who presented with focal right-sided seizures and was found to have a growing left insular mass determined to be a WHO grade II diffuse astrocytoma. After the initial open resection using frontotemporal craniotomy with transsylvian approach, gross total resection was achieved; however, the tumor recurred, as did the seizures. Six months postoperatively, the patient underwent laser ablation with MRgLITT for the recurrent tumor with complete removal. At both 1- and 6-months post re-operation, he has remained seizure free. MRgLITT management of LGG allows for both successfully reducing tumor burden and the amelioration of secondary seizures.

Magnetic resonance-guided stereotactic laser ablation therapy for the treatment of pediatric brain tumors: a multiinstitutional retrospective study

OBJECTIVE

This study aimed to assess the safety and efficacy of MR-guided stereotactic laser ablation (SLA) therapy in the treatment of pediatric brain tumors.

METHODS

Data from 17 North American centers were retrospectively reviewed. Clinical, technical, and radiographic data for pediatric patients treated with SLA for a diagnosis of brain tumor from 2008 to 2016 were collected and analyzed.

RESULTS

A total of 86 patients (mean age 12.2 ± 4.5 years) with 76 low-grade (I or II) and 10 high-grade (III or IV) tumors were included. Tumor location included lobar (38.4%), deep (45.3%), and cerebellar (16.3%) compartments. The mean follow-up time was 24 months (median 18 months, range 3-72 months). At the last follow-up, the volume of SLA-treated tumors had decreased in 80.6% of patients with follow-up data. Patients with high-grade tumors were more likely to have an unchanged or larger tumor size after SLA treatment than those with low-grade tumors (OR 7.49, p = 0.0364). Subsequent surgery and adjuvant treatment were not required after SLA treatment in 90.4% and 86.7% of patients, respectively. Patients with high-grade tumors were more likely to receive subsequent surgery (OR 2.25, p = 0.4957) and adjuvant treatment (OR 3.77, p = 0.1711) after SLA therapy, without reaching significance. A total of 29 acute complications in 23 patients were reported and included malpositioned catheters (n = 3), intracranial hemorrhages (n = 2), transient neurological deficits (n = 11), permanent neurological deficits (n = 5), symptomatic perilesional edema (n = 2), hydrocephalus (n = 4), and death (n = 2). On long-term follow-up, 3 patients were reported to have worsened neuropsychological test results. Pre-SLA tumor volume, tumor location, number of laser trajectories, and number of lesions created did not result in a significantly increased risk of complications; however, the odds of complications increased by 14% (OR 1.14, p = 0.0159) with every 1-cm3 increase in the volume of the lesion created.

CONCLUSIONS

SLA is an effective, minimally invasive treatment option for pediatric brain tumors, although it is not without risks. Limiting the volume of the generated thermal lesion may help decrease the incidence of complications.

Laser interstitial thermal therapy in gliomas

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

Corpus callosotomy performed with laser interstitial thermal therapy

OBJECTIVE

Corpus callosotomy is a palliative procedure that is effective at reducing seizure burden in patients with medically refractory epilepsy. The procedure is traditionally performed via open craniotomy with interhemispheric microdissection to divide the corpus callosum. Concerns for morbidity associated with craniotomy can be a deterrent to patients, families, and referring physicians for surgical treatment of epilepsy. Laser interstitial thermal therapy (LITT) is a less invasive procedure that has been widely adopted in neurosurgery for the treatment of tumors. In this study, the authors investigated LITT as a less invasive approach for corpus callosotomy.

METHODS

The authors retrospectively reviewed all patients treated for medically refractory epilepsy by corpus callosotomy, either partial or completion, with LITT. Chart records were analyzed to summarize procedural metrics, length of stay, adverse events, seizure outcomes, and time to follow-up. In select cases, resting-state functional MRI was performed to qualitatively support effective functional disconnection of the cerebral hemispheres.

RESULTS

Ten patients underwent 11 LITT procedures. Five patients received an anterior two-thirds LITT callosotomy as their first procedure. One patient returned after LITT partial callosotomy for completion of callosotomy by LITT. The median hospital stay was 2 days (IQR 1.5-3 days), and the mean follow-up time was 1.0 year (range 1 month to 2.86 years). Functional outcomes are similar to those of open callosotomy, with the greatest effect in patients with a significant component of drop attacks in their seizure semiology. One patient achieved an Engel class II outcome after anterior two-thirds callosotomy resulting in only rare seizures at the 18-month follow-up. Four others were in Engel class III and 5 were Engel class IV. Hemorrhage occurred in 1 patient at the time of removal of the laser fiber, which was placed through the bone flap of a prior open partial callosotomy.

CONCLUSIONS

LITT appears to be a safe and effective means for performing corpus callosotomy. Additional data are needed to confirm equipoise between open craniotomy and LITT for corpus callosotomy.

Single and staged laser interstitial thermal therapy ablation for cortical tubers causing refractory epilepsy in pediatric patients

OBJECTIVE Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a novel, minimally invasive treatment for the surgical treatment of epilepsy. In this paper, the authors report on clinical outcomes for a series of pediatric patients with tuberous sclerosis complex (TSC) and medication-refractory epileptogenic cortical tubers. METHODS A retrospective chart review was performed at SUNY Upstate Golisano Children's Hospital in Syracuse, New York. The authors included all cases involving pediatric patients (< 18 years) who underwent MRgLITT for ablation of epileptogenic cortical tubers between February 2013 and November 2015. RESULTS Seven patients with cortical tubers were treated (4 female and 3 male). The patients' average age was 6.6 years (range 2-17 years). Two patients had a single procedure, and 5 patients had staged procedures. The mean time between procedures in the staged cases was 6 months. All of the patients had a meaningful reduction in seizure frequency as reported by Engel and ILAE seizure outcome classifications, and most (71.4%) of the patients experienced a reduction in AED burden. Three of the 4 patients who presented with neuropsychiatric symptoms had some improvement in these domains after laser ablation. No perioperative complications were noted. The mean duration of follow-up was 19.3 months (range 4-49 months). CONCLUSIONS Laser ablation represents a minimally invasive alternative to resective epilepsy surgery and is an effective treatment for refractory epilepsy due to cortical tubers.

Neuronavigator-guided ventriculoscopic approach for symptomatic xanthogranuloma of the choroid plexus in the lateral ventricle

Xanthogranuloma of choroid plexus is an extremely rare, benign, and mostly asymptomatic intracranial lesion. We report a case of symptomatic lateral ventricular xanthogranuloma resected via a neuronavigator-guided ventriculoscopic approach. Then we review recent English medical literature and notice that craniotomies have been the most popular treatment. But our choice of a ventriculoscopic approach possesses unique advantages such as minimized neural tissue damage, shortened operative time, less blood loss, and safer access to central structures over conventional open surgeries. Informed consent has been obtained from the patient and his immediate family regarding this case report.

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.

Laser Ablation Therapy for Pediatric Patients with Intracranial Lesions in Eloquent Areas

BACKGROUND

Laser interstitial thermal therapy (LITT) is an alternative, less-invasive, and, in some circumstances, effective treatment for patients with intracranial pathology including epilepsy and some tumors. For intracranial lesions in eloquent areas, resection by conventional craniotomy proves often to be a challenge, including in the care of pediatric patients. Herein, we reviewed our experience with magnetic resonance imaging (MRI)-guided LITT as treatment for pediatric patients with intracranial lesions in eloquent areas and evaluate neurologic function and clinical outcomes.

METHODS

We retrospectively reviewed consecutive patients with intracranial lesions in eloquent speech and motor areas who underwent MRI-guided LITT. Clinical evaluation, including neurologic function and neuropsychological testing, was conducted according to clinical considerations. MRI pre- and postoperative imaging was reviewed to compare the change of lesion size.

RESULTS

Five pediatric patients received MRI-guided LITT of intracranial lesions in eloquent cortex. One patient experienced complications secondary to MRI-guided LITT, but neither was discharged with a neurologic deficit.

CONCLUSIONS

For intracranial lesions in the eloquent cortex, conventional craniotomy with surgical resection is a challenge for neurosurgeons, especially pediatric patients. MRI-guided LITT provides a less-invasive and potentially effective option for treatment in the management of pediatric epilepsy and tumors.

Trapped ventricle after laser ablation of a subependymal giant cell astrocytoma complicated by intraventricular gadolinium extravasation: case report

Magnetic resonance imaging-guided stereotactic laser ablation of intracranial targets, including brain tumors, has expanded dramatically over the past decade, but there have been few reports of complications, especially those occurring in a delayed fashion. Laser ablation of subependymal giant cell astrocytomas (SEGAs) is an attractive alternative to maintenance immunotherapy in some children with tuberous sclerosis complex (TSC); however, the effect of treatment on disease progression and the nature and frequency of potential complications remains largely unknown. The authors report the case of a 5-year-old boy with TSC who underwent stereotactic laser ablation of a SEGA at the right foramen of Monro on 2 separate occasions. After the second ablation, immediate posttreatment MRI revealed gadolinium extravasation from the tumor into the lateral ventricle. Nine months later, the patient presented with papilledema and delayed obstructive hydrocephalus secondary to intraventricular adhesions causing a trapped right lateral ventricle. This was successfully treated with endoscopic septostomy. The authors discuss the potential cause and clinical management of a delayed complication not previously reported after a relatively novel surgical therapy.

MRI-Guided Laser Interstitial Thermal Therapy for Epilepsy

MRI-guided laser interstitial thermal therapy for epilepsy (LITT-E) has become an established, minimally invasive alternative to traditional epilepsy surgery. LITT-E is particularly valuable in cases in which open surgery poses unacceptably high morbidity or patient preference precludes craniotomy. Here we present a focused review of technical details and application of LITT to both focal and generalized epilepsy.

Laser-Induced Thermal Therapy in Neuro-Oncology: A Review

OBJECTIVES

Laser therapy has become an appealing treatment modality in neurosurgery. In this review, we report on the history, physics, surgical steps, indications and uses, and complications that have been reported to date.

METHODS

An extensive literature search was performed for laser interstitial thermal therapy (LITT) and laser therapy in the context of glial tumors, metastatic lesions, pediatric brain tumors, and radiation necrosis. Reported complications in each series also were reviewed.

RESULTS

In the past decade, multiple studies have demonstrated the use, outcomes, and complications associated with LITT in neurosurgery. These same studies have consistently reported an overall benefit of LITT in cases in which traditional surgical approaches may be limited by the patient's clinical status, tumor location, or overall prognosis. However, there have been complications reported from local effects of thermal damage, technical error, and edema development. Increased experience has reduced complications and brought more promising results.

CONCLUSIONS

With the advent of real-time monitoring and damage estimation, LITT has gained ground in the management of intracranial tumors. Larger scale trials must be performed to develop standard protocols to define specific indications for use. Further large clinical studies for LITT in non-oncologic cases are also of interest.

Theoretical model for laser ablation outcome predictions in brain: calibration and validation on clinical MR thermometry images

PURPOSE

Neurosurgical laser ablation is experiencing a renaissance. Computational tools for ablation planning aim to further improve the intervention. Here, global optimisation and inverse problems are demonstrated to train a model that predicts maximum laser ablation extent.

METHODS

A closed-form steady state model is trained on and then subsequently compared to N = 20 retrospective clinical MR thermometry datasets. Dice similarity coefficient (DSC) is calculated to provide a measure of region overlap between the 57 °C isotherms of the thermometry data and the model-predicted ablation regions; 57 °C is a tissue death surrogate at thermal steady state. A global optimisation scheme samples the dominant model parameter sensitivities, blood perfusion (ω) and optical parameter (μ_eff) values, throughout a parameter space totalling 11 440 value-pairs. This represents a lookup table of μ_eff-ω pairs with the corresponding DSC value for each patient dataset. The μ_eff-ω pair with the maximum DSC calibrates the model parameters, maximising predictive value for each patient. Finally, leave-one-out cross-validation with global optimisation information trains the model on the entire clinical dataset, and compares against the model naïvely using literature values for ω and μ_eff.

RESULTS

When using naïve literature values, the model's mean DSC is 0.67 whereas the calibrated model produces 0.82 during cross-validation, an improvement of 0.15 in overlap with the patient data. The 95% confidence interval of the mean difference is 0.083-0.23 (p < 0.001).

CONCLUSIONS

During cross-validation, the calibrated model is superior to the naïve model as measured by DSC, with +22% mean prediction accuracy. Calibration empowers a relatively simple model to become more predictive.

Recent technological advances in pediatric brain tumor surgery

X-rays and ventriculograms were the first imaging modalities used to localize intracranial lesions including brain tumors as far back as the 1880s. Subsequent advances in preoperative radiological localization included computed tomography (CT; 1971) and MRI (1977). Since then, other imaging modalities have been developed for clinical application although none as pivotal as CT and MRI. Intraoperative technological advances include the microscope, which has allowed precise surgery under magnification and improved lighting, and the endoscope, which has improved the treatment of hydrocephalus and allowed biopsy and complete resection of intraventricular, pituitary and pineal region tumors through a minimally invasive approach. Neuronavigation, intraoperative MRI, CT and ultrasound have increased the ability of the neurosurgeon to perform safe and maximal tumor resection. This may be facilitated by the use of fluorescing agents, which help define the tumor margin, and intraoperative neurophysiological monitoring, which helps identify and protect eloquent brain.

Laser neurosurgery: A systematic analysis of magnetic resonance-guided laser interstitial thermal therapies

Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a novel minimally invasive modality that uses heat from laser probes to destroy tissue. Advances in probe design, cooling mechanisms, and real-time MR thermography have increased laser utilization in neurosurgery. The authors perform a systematic analysis of two commercially available MRgLITT systems used in neurosurgery: the Visualase® thermal therapy and NeuroBlate® Systems. Data extraction was performed in a blinded fashion. Twenty-two articles were included in the quantitative synthesis. A total of 223 patients were identified with the majority having undergone treatment with Visualase (n=154, 69%). Epilepsy was the most common indication for Visualase therapy (n=8 studies, 47%). Brain mass was the most common indication for NeuroBlate therapy (n=3 studies, 60%). There were no significant differences, except in age, wherein the NeuroBlate group was nearly twice as old as the Visualase group (p<0.001). Frame, total complications, and length-of-stay (LOS) were non-significant when adjusted for age and number of patients. Laser neurosurgery has evolved over recent decades. Clinical indications are currently being defined and will continue to emerge as laser technologies become more sophisticated. Head-to-head comparison of these systems was difficult given the variance in indications (and therefore patient population) and disparate literature.

MRI-guided laser interstitial thermal therapy for the treatment of low-grade gliomas in children: a case-series review, description of the current technologies and perspectives

BACKGROUND

Pediatric low-grade gliomas (LGGs) account for approximately half of all pediatric central nervous system tumors. The low-grade gliomas' first line of treatment is gross total resection. However, when gross total resection is not possible, options for adjuvant therapy are limited. MRI-guided laser ablation (magnetic resonance-guided laser interstitial thermal therapy (MRgLITT)) offers a new option for treatment in selected cases. We present a description of the current MRgLITT technology and an exemplary case-series review of our experience in its use in LGGs.

CASE DESCRIPTION

A 19-month-old male was referred to the pediatric neurosurgery clinic with an incidental left temporal lesion discovered on a prenatal ultrasound. An MRI of the brain revealed a diffuse mesial temporal lesion. Electroencephalogram (EEG) showed generalized activity arising from the lesion. The patient underwent a navigation-guided biopsy then, two bolts were secured to the skull, and laser ablation was performed with intraoperative MR guidance. Pathology was consistent with ganglioglioma. Follow-up images 13 months after ablation showed a significant volumetric reduction in size of the tumor.

DISCUSSION

It is important to achieve maximal resection of low-grade gliomas in children, lessening the need for adjuvant chemotherapy and radiotherapy, while minimizing the length of hospital stay and disruption to the child's life. Of our nine LGGs patients treated with this technology, six had undergone previous surgery and MRgLITT proved itself to be a safe surgical treatment option to achieve further cytoreduction. While most of the cases are pilocytic astrocytomas, the location of the tumors was surgically challenging. Eight of the nine cases required a single trajectory-laser-while our case example requires two lasers. Only a case of a midbrain-thalamic tumor presented a post-ablation significant brain edema as perioperative complication [1]. Eight of the nine tumors did not require any coadjuvant therapy or further surgical treatment to date.

CONCLUSION

MRIgLITT is a successful option for treatment for selected de novo or recurrent low-grade gliomas in children. It can be combined with other therapies offering the advantages of a minimally invasive procedure. LITT may be added to the current pediatric neuro-oncology protocols, but larger prospective series are needed to show the effectiveness of LITT and to standardize indications and protocols.