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

Modulation of Blood-Brain Barrier Permeability by Activating Adenosine A2 Receptors in Oncological Treatment

The blood–brain barrier (BBB) plays an important protective role in the central nervous system and maintains its homeostasis. It regulates transport into brain tissue and protects neurons against the toxic effects of substances circulating in the blood. However, in the case of neurological diseases or primary brain tumors, i.e., gliomas, the higher permeability of the blood-derived substances in the brain tissue is necessary. Currently applied methods of treatment for the primary brain neoplasms include surgical removal of the tumor, radiation therapy, and chemotherapy. Despite the abovementioned treatment methods, the prognosis of primary brain tumors remains bad. Moreover, chemotherapy options seem to be limited due to low drug penetration into the cancerous tissue. Modulation of the blood–brain barrier permeability may contribute to an increase in the concentration of the drug in the CNS and thus increase the effectiveness of therapy. Interestingly, endothelial cells in cerebral vessels are characterized by the presence of adenosine 2A receptors (A2AR). It has been shown that substances affecting these receptors regulate the permeability of the BBB. The mechanism of increasing the BBB permeability by A2AR agonists is the actin-cytoskeletal reorganization and acting on the tight junctions. In this case, the A2AR seems to be a promising therapy target. This article aims to assess the possibility of increasing the BBB permeability through A2AR agonists to increase the effectiveness of chemotherapy and to improve the results of cancer therapy.

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 Thermal Therapy in Patients with Newly Diagnosed Glioblastoma: A Systematic Review

BACKGROUND

Laser interstitial thermal therapy (LITT) is a minimal invasive neurosurgical technique for the treatment of brain tumors. Results of LITT have been reported in a case series of patients with deep seated and/or recurrent glioblastoma or cerebral metastases. With this review we aim to summarize the currently available evidence regarding safety and effectiveness of LITT in patients with newly diagnosed glioblastoma (nGBM).

METHODS

A literature search was performed using electronic databases (PubMed and Embase). Papers were assessed for the methodological quality using the Risk Of Bias In Non- randomised Studies - of Interventions (ROBINS-I) tool, and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) was used to assess the quality of the evidence.

RESULTS

We identified 835 papers of which only 11 articles were eligible for our review. All papers suffered from serious or critical risk of bias, and the quality of evidence was graded as very low according to the GRADE criteria. None of the studies was randomized and reporting of confounders and other parameters was poor. Median overall survival (OS) ranged from 4.1 to 32 months and progression free survival (PFS) from 2 to 31 months. The mean complication rate was 33.7%. No quality of life or cost-effectiveness data were reported.

CONCLUSIONS

Due to the low quality of the studies, it is not possible to draw firm conclusions regarding the (cost) effectiveness of LITT in patients with newly diagnosed glioblastoma. The low quality of evidence shows the need for a well-designed prospective multicenter randomized controlled trial.

Ultrasound Ablation in Neurosurgery: Current Clinical Applications and Future Perspectives

The concept of focusing high-intensity ultrasound beams for the purpose of cerebral ablation has interested neurosurgeons for more than 70 yr. However, the need for a craniectomy or a cranial acoustic window hindered the clinical diffusion of this technique. Recent technological advances, including the development of phased-array transducers and magnetic resonance imaging technology, have rekindled the interest in ultrasound for ablative brain surgery and have led to the development of the transcranial magnetic resonance-guided focused ultrasound (MRgFUS) thermal ablation procedure. In the last decade, this method has become increasingly popular, and its clinical applications are broadening. Despite the demonstrated efficacy of MRgFUS, transcranial thermal ablation using ultrasound is limited in that it can target exclusively the central region of the brain where the multiple acoustic beams are most optimally focused. On the contrary, lesioning of the cortex, the superficial subcortical areas, and regions close to the skull base is not possible with the limited treatment envelope of current phased-array transducers. Therefore, new ultrasound ablative techniques, which are not based on thermal mechanisms, have been developed and tested in experimental settings. This review describes the mechanisms by which these novel, nonthermal ablative techniques are based and also presents the current clinical applications of MRgFUS thermal ablation.

Graphene-laden hydrogels: A strategy for thermally triggered drug delivery

The synthesis of graphene-based materials has attracted considerable attention in drug delivery strategies. Indeed, the conductivity and mechanical stability of graphene have been investigated for controlled and tunable drug release via electric or mechanical stimuli. However, the design of a thermo-sensitive scaffold using pristine graphene (without distortions related to the oxidation processes) has not been deeply investigated yet, although it may represent a promising approach for several therapeutic treatments. Here, few-layer graphene was used as a nanofiller in a hydrogel system with a thermally tunable drug release profile. In particular, varying the temperature (25 °C, 37 °C and 44 °C), responsive drug releases were noticed and hypothesized depending on the formation and perturbation of π-π interactions involving graphene, the polymeric matrix and the model drug (diclofenac). As a result, these hybrid hydrogels show a potential application as thermally triggered drug release systems in several healthcare scenarios.

Stereotactic Laser Ablation of Glioblastoma

The previous decade has seen an expansion in the use of laser interstitial thermal therapy (LITT) for a variety of pathologies. LITT has been used to treat both newly diagnosed and recurrent glioblastoma (GBM), especially in deep-seated, difficult-to-access lesions where open resection is otherwise infeasible or in patients who would not tolerate craniotomy. This review aims to describe the current state of the technology and operative technique, as well as summarize the outcomes data and future research regarding LITT as a treatment of GBM.

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.

Changing Hands: A Rising Role of the Tumor Surgeon in Teaching Sylvian Fissure Dissection

OBJECTIVE

The landscape of microneurosurgery has changed considerably over the past 2 decades, with a decline in indications for open surgery on cerebrovascular pathology and ever-increasing indications for open resection of brain tumors. This study investigated how these trends in case volume affected residents' training experiences in microsurgery and, specifically, Sylvian fissure dissection.

METHODS

Resident case logs were reviewed, identifying open cerebrovascular operations and craniotomies for tumor. Operations involving Sylvian fissure dissection were identified through operative reports. Changes in case number by resident were plotted over time, and linear regression was applied.

RESULTS

Among 23 chief residents, 3045 operations were identified, 1071 of which were for cerebrovascular pathology and 1974 for tumor. Open cerebrovascular experience decreased (P < 0.0001) while tumor volume remained unchanged (P = 0.221). The number of Sylvian fissure dissections per resident did not change over time overall (P = 0.583) or within cerebrovascular operations (P = 0.071). The number of Sylvian fissure dissections in tumor operations increased (P = 0.004). This effect was predominated by an increase in intraaxial tumors approached via Sylvian fissure dissection (P = 0.003). The proportion of Sylvian fissure dissections in tumor surgery increased from 15% in 2009 to 34% by 2019 (P = 0.003).

CONCLUSIONS

Residents are seeing an increasing proportion of their Sylvian fissure dissection experience during tumor operations. The distribution of this experience will continue to evolve as surgical indications change but suggests a growing role for tumor surgeons in resident training in microsurgery.

Blood-Brain Barrier Disruption in Neuro-Oncology: Strategies, Failures, and Challenges to Overcome

The blood-brain barrier (BBB) presents a formidable challenge in the development of effective therapeutics in neuro-oncology. This has fueled several decades of efforts to develop strategies for disrupting the BBB, but progress has not been satisfactory. As such, numerous drug- and device-based methods are currently being investigated in humans. Through a focused assessment of completed, active, and pending clinical trials, our first aim in this review is to outline the scientific foundation, successes, and limitations of the BBBD strategies developed to date. Among 35 registered trials relevant to BBBD in neuro-oncology in the ClinicalTrials.gov database, mannitol was the most common drug-based method, followed by RMP-7 and regadenoson. MR-guided focused ultrasound was the most common device-based method, followed by MR-guided laser ablation, ultrasound, and transcranial magnetic stimulation. While most early-phase studies focusing on safety and tolerability have met stated objectives, advanced-phase studies focusing on survival differences and objective tumor response have been limited by heterogeneous populations and tumors, along with a lack of control arms. Based on shared challenges among all methods, our second objective is to discuss strategies for confirmation of BBBD, choice of systemic agent and drug design, alignment of BBBD method with real-world clinical workflow, and consideration of inadvertent toxicity associated with disrupting an evolutionarily-refined barrier. Finally, we conclude with a strategic proposal to approach future studies assessing BBBD.

Robot-assisted ultrasound navigation platform for 3D HIFU treatment planning: Initial evaluation for conformal interstitial ablation

Interstitial Ultrasound-guided High Intensity Focused Ultrasound (USgHIFU) therapy has the potential to deliver ablative treatments which conform to the target tumor. In this study, a robot-assisted US-navigation platform has been developed for 3D US guidance and planning of conformal HIFU ablations. The platform was used to evaluate a conformal therapeutic strategy associated with an interstitial dual-mode USgHIFU catheter prototype (64 elements linear-array, measured central frequency f = 6.5 MHz), developed for the treatment of HepatoCellular Carcinoma (HCC). The platform included a 3D navigation environment communicating in real-time with an open research dual-mode US scanner/HIFU generator and a robotic arm, on which the USgHIFU catheter was mounted. 3D US-navigation was evaluated in vitro for guiding and planning conformal HIFU ablations using a tumor-mimic model in porcine liver. Tumor-mimic volumes were then used as targets for evaluating conformal HIFU treatment planning in simulation. Height tumor-mimics (ovoid- or disc-shaped, sizes: 3-29 cm³) were created and visualized in liver using interstitial 2D US imaging. Robot-assisted spatial manipulation of these images and real-time 3D navigation allowed reconstructions of 3D B-mode US images for accurate tumor-mimic volume estimation (relative error: 4 ± 5%). Sectorial and full-revolution HIFU scanning (angular sectors: 88-360°) could both result in conformal ablations of the tumor volumes, as soon as their radii remained ≤ 24 mm. The presented US navigation-guided HIFU procedure demonstrated advantages for developing conformal interstitial therapies in standard operative rooms. Moreover, the modularity of the developed platform makes it potentially useful for developing other HIFU approaches.

Laser Interstitial Thermal Therapy for Metastatic Melanoma After Failed Radiation Therapy: A Case Series

BACKGROUND

Laser interstitial thermal therapy (LITT) is a growing technology to treat a variety of brain lesions. It offers an alternative to treatment options, such as open craniotomy and stereotactic radiosurgery.

OBJECTIVE

To analyze our experience using LITT for metastatic melanoma.

METHODS

This is a retrospective chart review of the patients from our institution. Our case series involves 5 patients who had previously failed radiation treatment.

RESULTS

Our patients have low complication rates and short hospital stays. Both are considerably lower when compared to the literature for metastatic melanoma.

CONCLUSION

LITT is a safe therapy, with few complications and short hospital stays.

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.

Ablative brain surgery: an overview

Background: Ablative therapies have been used for the treatment of neurological disorders for many years. They have been used both for creating therapeutic lesions within dysfunctional brain circuits and to destroy intracranial tumors and space-occupying masses. Despite the introduction of new effective drugs and neuromodulative techniques, which became more popular and subsequently caused brain ablation techniques to fall out favor, recent technological advances have led to the resurgence of lesioning with an improved safety profile. Currently, the four main ablative techniques that are used for ablative brain surgery are radiofrequency thermoablation, stereotactic radiosurgery, laser interstitial thermal therapy and magnetic resonance-guided focused ultrasound thermal ablation. Object: To review the physical principles underlying brain ablative therapies and to describe their use for neurological disorders. Methods: The literature regarding the neurosurgical applications of brain ablative therapies has been reviewed. Results: Ablative treatments have been used for several neurological disorders, including movement disorders, psychiatric disorders, chronic pain, drug-resistant epilepsy and brain tumors. Conclusions: There are several ongoing efforts to use novel ablative therapies directed towards the brain. The recent development of techniques that allow for precise targeting, accurate delivery of thermal doses and real-time visualization of induced tissue damage during the procedure have resulted in novel techniques for cerebral ablation such as magnetic resonance-guided focused ultrasound or laser interstitial thermal therapy. However, older techniques such as radiofrequency thermal ablation or stereotactic radiosurgery still have a pivotal role in the management of a variety of neurological disorders.

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.

Devascularization of a Hemorrhagic Pineocytoma by Laser Thermal Ablation Followed by Endoscopic Resection: A Proof-of-Principle Case Report

BACKGROUND

Thermal coagulation is a central principle in surgery, particularly regarding hemostasis, as well as being an integral part of intracranial tumor removal. Traditionally, surgical hemostasis is achieved through application of unipolar or bipolar electrocautery. This method has been contemporized and specialized to treat intracranial tumors through a technique called stereotactic laser ablation (SLA), also known as laser interstitial thermal therapy.

CASE DESCRIPTION

In this article, we present this technique as an additional option in the treatment of difficult intracranial tumors. Specifically, we report here a highly vascular and hemorrhagic pineocytoma found in a fragile, elderly patient who underwent a novel combination of procedures: SLA mediated devascularization followed by resection via an endoscopic approach.

CONCLUSIONS

SLA-mediated thermal-coagulation is a potential strategy for minimizing hemorrhagic risks in brain tumor resection and may be used in conjunction with other approaches tailored to the patient and their disease.

Lessons Learned in Using Laser Interstitial Thermal Therapy for Treatment of Brain Tumors: A Case Series of 238 Patients from a Single Institution

BACKGROUND

Laser interstitial thermal therapy (LITT) is a novel, minimally invasive alternative to craniotomy, and as with any new technology, comes with a learning curve.

OBJECTIVE

We present our experience detailing the evolution of this technology in our practice in one of the largest patient cohorts to date regarding LITT in neuro-oncology.

METHODS

We reviewed 238 consecutive patients with brain tumor treated with LITT at our institution. Data on patient, surgery and tumor characteristics, and follow-up were collected. Patients were categorized into 2 cohorts: early (<2014, 100 patients) and recent (>2015, 138 patients). Median follow-up for the entire cohort was 8.4 months.

RESULTS

The indications for LITT included gliomas (70.2%), radiation necrosis (21.0%), and metastasis (8.8%). Patient demographics stayed consistent between the 2 cohorts, with the exception of age (early, 54.3; recent, 58.4; P = 0.04). Operative time (6.6 vs. 3.5; P < 0.001) and number of trajectories (53.1% vs. 77.9% with 1 trajectory; P < 0.001) also decreased in the recent cohort. There was a significant decrease in permanent motor deficits over time (15.5 vs. 4.4%; P = 0.005) and 30-day mortality (4.1% vs. 1.5%) also decreased (not statistically significant) in the recent cohort. In terms of clinical outcomes, poor preoperative Karnofsky Performance Status (≤70) were significantly correlated with increased permanent deficits (P = 0.001) and decreased overall survival (P < 0.001 for all time points).

CONCLUSIONS

We observed improvement in operative efficiency and permanent deficits over time and also patients with poor preoperative Karnofsky Performance Status achieved suboptimal outcomes with LITT. As many other treatment modalities, patient selection is important in this procedure.

Thermal ablation of biological tissues in disease treatment: A review of computational models and future directions

Percutaneous thermal ablation has proven to be an effective modality for treating both benign and malignant tumours in various tissues. Among these modalities, radiofrequency ablation (RFA) is the most promising and widely adopted approach that has been extensively studied in the past decades. Microwave ablation (MWA) is a newly emerging modality that is gaining rapid momentum due to its capability of inducing rapid heating and attaining larger ablation volumes, and its lesser susceptibility to the heat sink effects as compared to RFA. Although the goal of both these therapies is to attain cell death in the target tissue by virtue of heating above 50°C, their underlying mechanism of action and principles greatly differs. Computational modelling is a powerful tool for studying the effect of electromagnetic interactions within the biological tissues and predicting the treatment outcomes during thermal ablative therapies. Such a priori estimation can assist the clinical practitioners during treatment planning with the goal of attaining successful tumour destruction and preservation of the surrounding healthy tissue and critical structures. This review provides current state-of-the-art developments and associated challenges in the computational modelling of thermal ablative techniques, viz., RFA and MWA, as well as touch upon several promising avenues in the modelling of laser ablation, nanoparticles assisted magnetic hyperthermia and non-invasive RFA. The application of RFA in pain relief has been extensively reviewed from modelling point of view. Additionally, future directions have also been provided to improve these models for their successful translation and integration into the hospital work flow.

Adapting to Space Limitations During Prone Real-Time Magnetic Resonance Imaging-Guided Stereotaxic Laser Ablation: Technical Pearls

BACKGROUND

New techniques of intraoperative magnetic resonance imaging (MRI)-guided stereotaxy enable minimally invasive approaches to intracranial pathology. Laser interstitial thermal therapy (LITT), convection-enhanced drug delivery, and stereotactic biopsy can be performed with a real-time confirmation of location and the ability to adjust for intracranial shift during the procedure. However, these procedures are constrained by patient positioning and the need for trajectories that avoid collision between stereotactic elements and the small MRI bore. To our knowledge, this is the first report to outline the technical details of safe intraoperative MRI (iMRI)-guided stereotaxy, performed with prone positioning.

OBJECTIVE

To present technical pearls to guide the safe conduction of iMRI-guided stereotaxy and LITT while in the prone position.

METHODS

The details of the positioning and trajectories for a series of patients who underwent Clearpoint® (MRI Interventions Inc) frameless real-time MRI-guided stereotaxis using a posterior approach were reviewed.

RESULTS

In this series, 5 patients underwent selective amygdalohippocampectomy, and 2 underwent tumor biopsy/ablation while in the prone position without any complications.

CONCLUSION

Prone iMRI procedures can be performed safely even in a 60-cm MRI bore.

Current Trends for Improving Safety of Stereotactic Brain Biopsies: Advanced Optical Methods for Vessel Avoidance and Tumor Detection

Stereotactic brain needle biopsies are indicated for deep-seated or multiple brain lesions and for patients with poor prognosis in whom the risks of resection outweigh the potential outcome benefits. The main goal of such procedures is not to improve the resection extent but to safely acquire viable tissue representative of the lesion for further comprehensive histological, immunohistochemical, and molecular analyses. Herein, we review advanced optical techniques for improvement of safety and efficacy of stereotactic needle biopsy procedures. These technologies are aimed at three main areas of improvement: (1) avoidance of vessel injury, (2) guidance for biopsy acquisition of the viable diagnostic tissue, and (3) methods for rapid intraoperative assessment of stereotactic biopsy specimens. The recent technological developments in stereotactic biopsy probe design include the incorporation of fluorescence imaging, spectroscopy, and label-free imaging techniques. The future advancements of stereotactic biopsy procedures in neuro-oncology include the incorporation of optical probes for real-time vessel detection along and around the biopsy needle trajectory and in vivo confirmation of the diagnostic tumor tissue prior to sample acquisition.

Microneuroanatomy of the Anterior Frontal Laser Trajectory to the Insula

BACKGROUND

Magnetic resonance imaging-guided laser interstitial thermal therapy (LITT) is an emerging minimally invasive procedure for the treatment of deep intracranial lesions. Insular lesions are challenging to treat because of the risk of damaging important surrounding structures. The precise knowledge of the neural structures that are at risk along the trajectory and during the ablation is essential to reduce associated complications. This study aims to describe the relevant anatomy of the anterior frontal LITT trajectory to the insular region by using sectional anatomy and fiber dissection technique.

METHODS

Three silicone-injected cadaveric heads were used to implant laser catheters bilaterally to the insular region by using a frameless stereotactic technique from a frontal approach. Sections were cut in both the oblique axial plane parallel to the trajectory and in the coronal plane. White matter fiber dissections were used to establish the tracts related to the laser trajectory from lateral to medial and medial to lateral.

RESULTS

Supraorbital regions were selected as entry points. After crossing the frontal bone, the track intersected the inferior frontal lobe. The catheter was illustrated reaching the insular region medial to the inferior fronto-occipital fasciculus and insular cortex, and superior to the uncinate fasciculus. The uncinate fasciculus, extreme capsule, claustrum, external capsule, and putamen were traversed, preserving the major vascular structures.

CONCLUSIONS

Independent of the insular area treated, an understanding of the neuroanatomy related to the anterior frontal laser trajectory is essential to improve the ability to perform LITT of this challenging region.

Delayed Onset Cyst Formation After Laser Interstitial Thermal Therapy: An Unreported Long-term Complication

The majority of complications following LITT therapy occur in the early post-operative period, with few long-term complications being reported. Here we present 2 cases of delayed onset cyst formation occurring more than 1 year following ablation, a previously unreported complication. In the first case, a 59 year-old female who previously underwent LITT for a radiation induced cavernoma developed a 2 cm cystic lesion 18 months following ablation, resulting in recurrent seizure. In the second case, 53 year-old female with a recurrent left frontal cerebral metastasis developed a large cystic lesion 30 months post ablation. Both patients required craniotomies and resection of their cystic lesions. In both cases pathology demonstrated reactive gliosis and blood vessel sclerosis. We hypothesize chronic gliosis following LITT therapy results in blood vessel sclerosis leading to blood-brain-barrier breakdown and resulting delayed cyst formation. These findings support need for long-term surveillance of patients treated with LITT.

History of Hemostasis in Neurosurgery

Control of bleeding in the confined area of the skull is imperative for successful neurosurgery and the prevention of devastating complications such as postoperative hemorrhage. This paper reviews the historical evolution of methods to achieve successful hemostasis in neurosurgery from the early1800s to today. The major categories of hemostatic agents (mechanical, chemical and thermal) are delineated and discussed in chronological order. The significance of this article is in its detailed history of the kinds of hemostatic methods that have evolved with our accumulating medical and surgical knowledge, which may inform future innovations and improvements.

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.