Stereotactic Laser Ablation Research Articles

Robot Assisted Stereotactic Laser Ablation for a Radiosurgery Resistant Hypothalamic Hamartoma.

Hypothalamic hamartomas (HH) are benign tumors that can cause significant morbidity in adults as a cause of epilepsy, particularly gelastic seizures. Open and endoscopic resections of HH offer good seizure control but have high rates of morbidity and are technically challenging. Stereotactic radiosurgery has been an alternative treatment; however, it results in comparably poor seizure control. Recently, in children, stereotactic laser ablation has shown promise as a surgical technique that can combine the best features of both of these approaches for the treatment of HH. Here we present the first reported use of a frameless robot-assisted stereotactic system to treat an HH. The patient had failed two previous Gamma Knife radiosurgery treatments. Post-procedure he had a stable, but unintentional weight loss of 20 kg and a transient episode of hemiparesis the night of the operation. At six months postoperatively the patient remained seizure free. Stereotactic laser ablation may represent a new standard in the treatment of HH in adults, especially in those who have failed radiosurgery. Further study is warranted in this population to determine efficacy and safety profiles.

A Methodology for Systematic Volumetric Analysis of Perioperative Cranial Imaging in Neurosurgical Patients

Although objective assessment of perioperative imaging provides a rigorous evaluation method of neurosurgical techniques in epilepsy, its use remains far from mainstream. Open surgery remains the gold standard for treatment of mesial temporal lobe epilepsy (MTLE); however, stereotactic laser ablation is a promising minimally invasive alternative. Nevertheless, the variables that may affect seizure outcome in stereotactic laser amygdalohippocampectomy (SLAH) remain unclear. While an objective endpoint such as ablated mesial temporal volumes may be significant, a standard methodology for calculating such volumes has yet to be proposed.

Stereotactic laser ablation of the splenium for intractable epilepsy.

Partial or complete corpus callosotomies have been applied, traditionally via open surgical or radiosurgical approaches, for the treatment of epilepsy in patients with multifocal tonic, atonic, or myoclonic seizures. Minimally invasive methods, such as MRI-guided laser interstitial thermal ablation (MTLA), are being employed to functionally remove or ablate seizure foci in the treatment of epilepsy. This therapy can achieve effectiveness similar to that of traditional resection, but with reduced morbidity compared with open surgery. Here, we present a patient with a history of prior partial corpus callosotomy who continued to suffer from medically refractory epilepsy with bisynchronous onset. We report on the utilization of laser ablation of the splenium in this patient to achieve full corpus callosotomy. Adequate ablation of the splenial remnant was confirmed by postoperative MRI imaging, and at four-month follow-up, the patient's seizure frequency had dropped more than 50%. This is the first reported instance of laser ablation of the splenium to achieve full corpus callosotomy following a previous unsuccessful anterior callosotomy in a patient with intractable generalized epilepsy.

PTCT-02STEREOTACTIC LASER INTERSTITIAL ABLATION THERAPY FOR PEDIATRIC LOW-GRADE GLIAL NEOPLASMS

INTRODUCTION: Slowly growing deeply situated brain tumors in children pose a unique management dilemma. Considerations of watchful waiting, resection, chemotherapy and radiation therapy must be weighed carefully. With concerns over neurosurgical resection morbidity, the typical long-term ineffectiveness of chemotherapy and the feared sequelae of radiation therapy, our institution has chosen to manage select tumors using laser interstitial ablation via the stereotactic Visualase® system. METHODS: Five patients, ages 7, 8, 12, 15, 16 years had clinicoradiographic histories of slowly enlarging deep brain lesions characteristic of low-grade glial tumors. Locations included deep thalamus (2), cerebellar vermis (1), parieto-occiptal region (1) and a SEGA near a foramen of Monro (1). Options for management were discussed with each family, and laser ablation was decided upon. RESULTS: The patients were taken to the intraoperative MRI operating room for stereotactic needle biopsy and laser interstitial ablation during the same operation. Frozen section tissue analysis in all cases showed a low-grade glial tumor. Each patient underwent standard post-operative scanning, all showing evidence of lesional/peri-lesional signal change, a sign suggestive of desired zonal ablation injury to the tumor. Four patients had no evidence of post-procedure complications and were discharged several days post-procedure. One patient (cerebellar vermis) had significant post-ablation procedure ataxia and had evidence of incomplete ablation by virtue of tumor progression 16 months later, requiring a second ablation. None had evidence of concerning hemorrhage. All tumors were finalized as being low-grade glial (pilocytic) tumors. CONCLUSIONS: Stereotactic laser ablation therapy should be considered as an option in the management of select patients with deeply-situated glial tumors, in order to avoid potential serious neurosurgical morbidity via resection, or the dangers of irradiation. Continued long-term patient follow up will be needed in order to determine whether ablation therapy was successful. Further reporting on this technique by other investigators is suggested.

Magnetic Resonance Thermometry-Guided Stereotactic Laser Ablation of Cavernous Malformations in Drug-Resistant Epilepsy: Imaging and Clinical Results.

Surgery is indicated for cerebral cavernous malformations (CCM) that cause medically refractory epilepsy. Real-time magnetic resonance thermography (MRT)-guided stereotactic laser ablation (SLA) is a minimally invasive approach to treating focal brain lesions. SLA of CCM has not previously been described. To describe MRT-guided SLA, a novel approach to treating CCM-related epilepsy, with respect to feasibility, safety, imaging, and seizure control in 5 consecutive patients. Five patients with medically refractory epilepsy undergoing standard presurgical evaluation were found to have corresponding lesions fulfilling imaging characteristics of CCM and were prospectively enrolled. Each underwent stereotactic placement of a saline-cooled cannula containing an optical fiber to deliver 980-nm diode laser energy via twist drill craniostomy. MR anatomic imaging was used to evaluate targeting prior to ablation. MR imaging provided evaluation of targeting and near real-time feedback regarding extent of tissue thermocoagulation. Patients maintained seizure diaries, and remote imaging (6-21 months post-ablation) was obtained in all patients. Imaging revealed no evidence of acute hemorrhage following fiber placement within presumed CCM. MRT during treatment and immediate post-procedure imaging confirmed desired extent of ablation. We identified no adverse events or neurological deficits. Four of 5 (80%) patients achieved freedom from disabling seizures after SLA alone (Engel class 1 outcome), with follow-up ranging 12-28 months. Reimaging of all subjects (6-21 months) indicated lesion diminution with surrounding liquefactive necrosis, consistent with the surgical goal of extended lesionotomy. Minimally invasive MRT-guided SLA of epileptogenic CCM is a potentially safe and effective alternative to open resection. Additional experience and longer follow-up are needed.

MRI-guided stereotactic laser ablation of mesial temporal structures for the treatment of refractory temporal lobe epilepsy (S31.008)

MRI-guided stereotactic laser ablation of mesial temporal structures for the treatment of refractory temporal lobe epilepsy (S31.008)

Disabling amnestic syndrome following stereotactic laser ablation of a hypothalamic hamartoma in a patient with a prior temporal lobectomy.

A 19-year-old man with cortical dysplasia and intractable focal seizures underwent a right temporal lobectomy. A hypothalamic hamartoma was subsequently recognized, and he then underwent MRI-guided stereotactic laser ablation. Unfortunately, he sustained damage to the bilateral medial mammillary bodies and suffered significant memory loss. We review laser ablation therapy for hypothalamic hamartomas and the anatomy of the memory network. We postulate that his persistent memory disorder resulted from a combination of the right temporal lobectomy and injury to the bilateral medial mammillary bodies.

Stereotactic laser ablation of high-grade gliomas.

Evolving research has demonstrated that surgical cytoreduction of a high-grade glial neoplasm is an important factor in improving the prognosis of these difficult tumors. Recent advances in intraoperative imaging have spurred the use of stereotactic laser ablation (laser interstitial thermal therapy [LITT]) for intracranial lesions. Among other targets, laser ablation has been used in the focal treatment of high-grade gliomas (HGGs). The revived application of laser ablation for gliomas parallels major advancements in intraoperative adjuvants and groundbreaking molecular advances in neuro-oncology. The authors review the research on stereotactic LITT for the treatment of HGGs and provide a potential management algorithm for HGGs that incorporates LITT in clinical practice.

Introduction: Glioblastoma: an update on pathophysiology and management strategies.

Glioblastoma multiforme remains an enigma for neu­ rooncology; our understanding has progressed, but the prognosis is still poor. In this issue of Neurosurgical Focus, the emphasis is on presenting current understanding of the pathophysiology of the disease and the manage­ ment strategies that stem from it. The issue can be divided into current management strategies and future treatments based on recent advances in understanding glioblastoma pathophysiology, including cancer stem cells, angiogen­ esis, and tumor heterogeneity. The first part of the issue is devoted to an evaluation of treatment methods available to patients today. From an operative standpoint, Hawasli et al. present a timely ar­ ticle on the use of stereotactic laser ablation of high­grade gliomas, a procedure that is available to most neurosur­ geons using the current armamentarium of imaging and ablative equipment. Lescher and colleagues assert that the time frame for the evaluation of postoperative chang­ es versus residual tumor is important in determining the extent of resection, given increasing data showing sur­ vival benefits with radiographically grossor near-total resections. From a medical perspective, Barbagallo et al. report data on long­term treatment with temozolomide, whereas Pompili et al. describe palliative care and end of life issues for patients with glioblastoma. The second part of this issue emphasizes the role of future treatments that will stem from recent advances in understanding the pathophysiology of glioblastoma mul­ tiforme. Sundar et al. present a timely review on the role of cancer stem cells in glioblastoma, which is followed by Khan and Ehtesham’s article on treatment based on targeting glioma stem cells. The importance and role of angiogenesis in glioblastoma pathophysiology is demon­ strated in Womeldorff et al.’s article on the role of hy­ poxia­inducible factor­1, hypoxia, and cytokine­induced angiogenesis. Understanding the role of angiogenesis leads to a better evaluation of the role of bevacizumab in glioblastoma treatment (Castro and Aghi) and the role of MET activation as a reaction to its use (Awad et al.). Tumor heterogeneity and the microenvironment are well recognized in glioblastoma, but recent advances in mo­ lecular genomics enable not only a precise diagnosis, but also prognostic implications. Aum et al. present a pre­ cise overview of the molecular and cellular heterogene­ ity found in glioblastoma. Golden et al. report preclinical data on the role of chloroquine and autophagy in glioblas­ toma. Two genes with important prognostic implications have recently been identified: IDH (Agnihotri et al.) and WT1 (Broaddus et al.). Identification of these targets can lead to new molecularly targeted therapies (Lau et al.). Treatment of glioblastoma requires a multidisciplin­ ary approach based on understanding the pathophysiol­ ogy of the disease, which will eventually lead to a better prognosis and quality of life for our patients. (http://thejns.org/doi/abs/10.3171/2014.9.FOCUS14677)

Independent Bilateral Hypothalamic Hamartomas and Gelastic Seizures: What Treatment to Offer?

We report a case of a 9-year-old boy with normal cognitive and neurological status. Pharmacoresistant epilepsy started at 2 years of age when he woke up from sleep with epigastric painful sensations. During the course, somatosensory seizures with pain in the legs and, from 3.2 years on, gelastic seizures and dyscognitive seizures occurred. High-resolution magnetic resonance image (MRI) of the brain revealed bilateral independent hypothalamic hamartomas in the supramamillary region. After presurgical evaluation, a decision for an endoscopic resection of the bigger, right-sided hamartoma was made. Seizures improved transiently after surgery (Engel 3a). However, no significant improvement was noted 6 months after surgery. As the only negative consequence, a marked weight gain followed surgery. Cognitive functions remained stable. On the basis of this case, we discuss the therapeutic options for this rare condition which include resection of the contralateral hamartoma or stereotactic laser ablation.

191 Methodology for Critical Evaluation of Laser Placement in Stereotactic Laser Ablation for Mesial Temporal Lobe Epilepsy

191 Methodology for Critical Evaluation of Laser Placement in Stereotactic Laser Ablation for Mesial Temporal Lobe Epilepsy

New aspects in the field of epilepsy

Regarding epilepsy several new developments can be reported. The International League Against Epilepsy (ILAE) has suggested a new definition of epilepsy, for the first time including a definition of epilepsy resolution. Progress in the diagnosis relates to new genetic findings, improvements in magnetic resonance imaging (MRI) and the increasing use of stereo electroencephalograms (sEEG). Regarding treatment there are new clinically relevant data on the pathophysiology and prevention of sudden unexpected death in epilepsy (SUDEP). Zonisamide has been approved by the European Medicines Agency (EMA) for monotherapy in adults with focal seizures and combination therapy in children aged ≥ 6 years. Retigabin and perampanel have been approved but are currently taken off the market in Germany (only) because the Gemeinsamer Bundesausschuss (GBA, Joint Federal Committee) did not find any additional therapeutic value as compared to lamotrigine due to a lack of data. A decision regarding a new application for perampanel is pending. Regarding surgical treatment novel ablation techniques (e.g. stereotactic radiofrequency and laser ablation as well as focussed ultrasound ablation) and brain stimulation paradigms are under investigation. Experimental studies, generously supported by the European Union (EU) and the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) are focusing on (opto-)genetic (e.g. using lentoviral transfection), epigenetic (e.g. micro-RNA-related) approaches and on the investigation of neuronal micronetworks.

Stereotactic Laser Ablation of Hippocampus Leads to Better Cognitive Outcome Than Open Temporal Lobe Resections for the Treatment of Epilepsy (S43.003)

Stereotactic Laser Ablation of Hippocampus Leads to Better Cognitive Outcome Than Open Temporal Lobe Resections for the Treatment of Epilepsy (S43.003)

Extraventricular Long-Axis Cannulation of the Hippocampus

Patients with hippocampal epileptogenic foci may benefit from targeted intracranial monitoring of seizures and treatments such as hippocampal electrical stimulation, closed-loop stimulation, and stereotactic laser ablation. Each may benefit from a greater volume of hippocampal coverage with long-axis cannulation. Furthermore, an extraventricular trajectory avoids brain shift and reduces the risk of hemorrhage from ependymal breach. Unfortunately, detailed descriptions of the technical aspects of longitudinal cannulation of the hippocampus remain sparse. To develop a standard protocol for extraventricular longitudinal hippocampal cannulation. Images from 25 patients stereotactically implanted with 27 longitudinal hippocampal devices were retrospectively reviewed to determine the location of the burr hole or twist drill craniostomy. Simulated planning for bilateral occipital trajectories was then performed on a second cohort of 25 patients (50 trajectories) with mesial temporal sclerosis. An entry point derived from these 77 trajectories was subsequently validated on a third cohort of 25 patients (50 trajectories). Extraventricular long-axis hippocampal implantation necessitates a lateral-to-medial and cephalad-to-caudal trajectory that skirts the inferomedial border of the temporal horn. Measurements from 64 trajectories suggested a consensus entry point that successfully facilitated 50 test trajectories as well as frame placement on 4 patients requiring long-axis hippocampal cannulation. Although trajectories must be individually tailored for each patient, we recommend a starting entry point approximately 5.5 cm superior to the external occipital protuberance and 5.5 cm lateral to midline for extraventricular long-axis hippocampal cannulation in adult patients. Identification of this point is particularly important when positioning the stereotactic frame.

Robot-Assisted Stereotactic Laser Ablation in Medically Intractable Epilepsy

Stereotactic laser ablation offers an advantage over open surgical procedures for treatment of epileptic foci, tumors, and other brain pathology. Robot-assisted stereotactic laser ablation could offer an accurate, efficient, minimally invasive, and safe method for placement of an ablation catheter into the target. To determine the feasibility of placement of a stereotactic laser ablation catheter into a brain lesion with the use of robotic assistance, via a safe, accurate, efficient, and minimally invasive manner. A laser ablation catheter (Visualase, Inc) was placed by using robotic guidance (ROSA, Medtech Surgical, Inc) under general anesthesia into a localized epileptogenic periventricular heterotopic lesion in a 19-year-old woman with 10-year refractory focal seizure history. The laser applicator (1.65 mm diameter) position was confirmed by using magnetic resonance imaging (MRI). Ablation using the Visualase system was performed under multiplanar imaging with real-time thermal imaging and treatment estimates in each plane. A postablation MRI sequence (T1 postgadolinium contrast injection) was used to immediately confirm the ablation. MRI showed accurate skin entry point and trajectory, with the applicator advanced to the lesion's distal boundary. Ablation was accomplished in less than 3 minutes of heating. The overall procedure, from time of skin incision to end of last ablation, was approximately 90 minutes. After confirmation of proper lesioning by using a T1 contrast-enhanced MRI, the applicator was removed, and the incision was closed using a single stitch. No hemorrhage or other untoward complication was visualized. The patient awoke without any complication, was observed overnight after admitting to a regular floor bed, and was discharged to home the following day. This technique, using a combination of Visualase laser ablation, ROSA robot, and intraoperative MRI, facilitated a safe, efficacious, efficient, and minimally invasive approach that could be used for placement of 1 or multiple electrodes in the future.

Hypothalamic hamartomas: Optimal approach to clinical evaluation and diagnosis

Hypothalamic hamartomas (HHs) present a difficult medical problem, manifested by gelastic seizures, which are often medically intractable. Although existing techniques offer modest surgical outcomes with the potential for significant morbidity, the relatively novel technique of magnetic resonance imaging (MRI)-guided stereotactic laser ablation (SLA) offers a potentially safer, minimally invasive method with high efficacy for the HH treatment. We report here on 14 patients with medically refractory gelastic epilepsy who underwent stereotactic frame-based placement of an MR-compatible laser catheter (1.6 mm diameter) through a 3.2-mm twist drill hole. A U.S. Food and Drug Administration (FDA)-cleared laser surgery system (Visualase, Inc.) was utilized to ablate the HH, using real-time MRI thermometry. Seizure freedom was obtained in 12 (86%) of 14 cases, with mean follow-up of 9 months. There were no permanent surgical complications, neurologic deficits, or neuroendocrine disturbances. One patient had a minor subarachnoid hemorrhage that was asymptomatic. Most patients were discharged home within 1 day. SLA was demonstrated to be a safe and effective minimally invasive tool in the ablation of epileptogenic HH. Because use of SLA for HH is being adopted by other medical centers, further data will be acquired to help treat this difficult disorder.

MR-guided stereotactic laser ablation of epileptogenic foci in children

ObjectiveFor about 30% of epilepsy patients, pharmaceutical therapy fails to control their seizures. MR-guided laser interstitial thermal therapy (MRgLITT) allows for real-time thermal monitoring of the ablation process and feedback control over the laser energy delivery. We report on minimally invasive surgical techniques of MRgLITT and short‐term follow-up results from the first five pediatric cases in which this system was used to ablate focal epileptic lesions. MethodsWe studied the patients with MRI of the brain, localized the seizure with video‐EEG and used the Visualase Thermal Therapy 25 System for laser ablation of their seizure foci. ResultsAll 5 patients are seizure free and there were no complications as of 2–13‐month follow-up. ConclusionMR‐guided laser interstitial thermal therapy has a significant potential to be a minimally invasive alternative to more conventional techniques to surgically treat medically refractory epilepsy in children.