Hypothalamic hamartoma and seizures: a treatable epileptic encephalopathy

Hypothalamic Hamartomas: A Narrative Review

Hypothalamic hamartomas (HH) are infrequent, non-neoplastic malformations of the hypothalamus with heterogeneous clinical features, with symptoms including gelastic seizures, central precocious puberty, and cognitive or behavioral deficits. This narrative review synthesizes current knowledge regarding the etiology, clinical manifestations, diagnostic advances, and therapeutic approaches for HH. Genetic insights highlight the role of postzygotic mosaicism and dysregulated Sonic Hedgehog signaling in HH development, emphasizing their relevance in potential therapeutic strategies. Diagnostic modalities such as MRI, PET, and SEEG are pivotal in identifying and characterizing HHs, enabling precise treatment planning. Therapeutic interventions span pharmacological, surgical, and neuromodulatory approaches. While surgical approaches, such as transcallosal resection or stereotactic radiosurgery, can offer considerable seizure control, newer modalities, such as laser interstitial laser thermal therapy (LITT) as well as stereotactic radiofrequency thermocoagulation, prioritize minimizing both cognitive and behavioral sequelae. The use of pharmacologic management and neuromodulation provides adjuvant benefits, specifically in drug-resistant epilepsy; despite progress, limitations still remain, including variability of outcomes and not enough long-term studies. This review underscores the need for multidisciplinary care and advanced research to optimize outcomes and improve the quality of life for patients with HH.

Endoscopic endonasal resection of olfactory tract hamartoma for pediatric epilepsy

BACKGROUND

Non-hypothalamic glioneural hamartomas are rare entities known to cause medically refractory epilepsy. Olfactory bulb hamartomas, in particular, are exceptionally rare.

METHODS

We describe a case of an olfactory bulb hamartoma that was surgically resected at our institution. We also performed a literature review of all glioneural hamartomas and discuss the clinical presentation, diagnosis, and management of these lesions.

RESULTS

Herein, we present the unusual case of a typically developing 17-year-old boy with a near life-long history of drug-resistant epilepsy, found to have a 0.8 × 1.0 cm right olfactory bulb hamartoma. Endoscopic endonasal trans-cribriform resection of the lesion led to seizure freedom in the 6-month follow-up period (Engel class 1 outcome). Comprehensive literature review revealed only one other sporadic case, which was also successfully treated with total surgical resection.

CONCLUSIONS

Our case of an olfactory bulb hamartoma adds to the limited literature currently available, illustrating key clinical characteristics of these exceedingly rare lesions and outlining an effective, minimally invasive, and low-morbidity treatment strategy.

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

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

Surgical and radiosurgical treatment of hypothalamic hamartoma: The Italian experience between 2011 and 2021

OBJECTIVE

To investigate the Italian experience on the surgical and radiosurgical treatment of drug-resistant epilepsy due to hypothalamic hamartoma (HH) in the period 2011-2021 in six Italian epilepsy surgery centers, and to compare safety and efficacy profiles of the different techniques.

METHODS

We collected pseudo-anonymized patient's data with at least 12 months of follow-up. Surgical outcome was defined according to Engel classification of seizure outcome. Univariate analysis was performed to assess the risk of post-operative seizures, categorized in dichotomous variable as favorable and unfavorable; explanatory variables were considered. Mann-Whitney or Chi-squared test were used to assess the presence of an association between variables (p < 0.05).

RESULTS

Full presurgical and postoperative data about 42 patients from 6 epilepsy surgery centers were gathered. Engel class I was reached in the 65.8% and 66.6% of patients with gelastic and non-gelastic seizures, respectively. Other than daily non-gelastic seizures were associated with seizure freedom (p = 0.01), and the radiological type presented a trend toward significance (p = 0.12).

SIGNIFICANCE

Endoscopic disconnection and laser interstitial thermal therapy are effective in the treatment of HH-related epilepsy, with a tolerable safety profile. Both gelastic and non-gelastic seizures can be treated, also in patients with a long history of seizures.

PLAIN LANGUAGE SUMMARY

This study collected data about 42 patients with HH-related epilepsies. Endoscopic disconnection and laser therapy are both effective and safe in the treatment of hypothalamic hamartoma-related epilepsies.

Intraoperative changes in large-scale thalamic circuitry following laser ablation of hypothalamic hamartomas

BACKGROUND AND OBJECTIVES

Gelastic seizures due to hypothalamic hamartomas (HH) are challenging to treat, in part due to an incomplete understanding of seizure propagation pathways. Although magnetic resonance imaging-guided laser interstitial thermal therapy (MRgLITT) is a promising intervention to disconnect HH from ictal propagation networks, the optimal site of ablation to achieve seizure freedom is not known. In this study, we investigated intraoperative post-ablation changes in resting-state functional connectivity to identify large-scale networks associated with successful disconnection of HH.

METHODS

Children who underwent MRgLITT for HH at two institutions were consecutively recruited and followed for a minimum of one year. Seizure freedom was defined as Engel score of 1A at the last available follow-up. Immediate pre- and post- ablation resting-state functional MRI scans were acquired while maintaining a constant depth of general anesthetic. Multivariable generalized linear models were used to identify intraoperative changes in large-scale connectivity associated with seizure outcomes.

RESULTS

Twelve patients underwent MRgLITT for HH, five of whom were seizure-free at their last follow-up. Intraprocedural changes in thalamocortical circuitry involving the anterior cingulate cortex were associated with seizure-freedom. Children who were seizure-free demonstrated an increase and decrease in connectivity to the pregenual and dorsal anterior cingulate cortices, respectively. In addition, children who became seizure-free demonstrated increased thalamic connectivity to the periaqueductal gray immediately following MRgLITT.

DISCUSSION

Successful disconnection of HH is associated with intraoperative, large-scale changes in thalamocortical connectivity. These changes provide novel insights into the large-scale basis of gelastic seizures and may represent intraoperative biomarkers of treatment success.

Multimodal Approach for the Treatment of Complex Hypothalamic Hamartomas

Hypothalamic hamartomas (HHs) are rare congenital lesions formed by heterotopic neuronal and glial cells attached to the mammillary bodies, tuber cinereum, and hypothalamus.They often present with an intractable epilepsy typically characterized by gelastic seizures but commonly associated with other types of refractory seizures. The clinical course is progressive in most of the cases, starting with gelastic seizures in infancy and deteriorating into complex seizure disorders that result in catastrophic epilepsy associated with cognitive decline and behavioral disturbances.Hamartomas are known to be intrinsically epileptogenic and the site of origin for the gelastic seizures. As antiepileptic drugs are typically ineffective in controlling HH-related epilepsy, different surgical options have been proposed as a treatment to achieve seizure control. Resection or complete disconnection of the hamartoma from the mammillothalamic tract has proved to achieve a long-lasting control of the epileptic syndrome.Usually, symptoms and their severity are typically related to the size, localization, and type of attachment. Precocious puberty appears mostly in the pedunculated type, while epileptic syndrome and behavioral decline are frequently related to the sessile type. For this reason, different classifications of HHs have been developed based on their size, extension, and type of attachment to the hypothalamus.The bigger and more complex hypothalamic hamartomas typically present with severe refractory epilepsy, behavioral disturbances, and progressive cognitive decline posing a formidable challenge for the control of these symptoms.We present here our experience with the multimodal treatment for complex hypothalamic hamartomas. After an in-depth review of the literature, we systematize our approach for the different types of hypothalamic hamartomas.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Brain mosaicism of hedgehog signalling and other cilia genes in hypothalamic hamartoma

Hypothalamic hamartoma (HH) is a rare benign developmental brain lesion commonly associated with a well characterized epilepsy phenotype. Most individuals with HH are non-syndromic without additional developmental anomalies nor a family history of disease. Nonetheless, HH is a feature of Pallister-Hall (PHS) and Oro-Facial-Digital Type VI (OFD VI) syndromes, both characterized by additional developmental anomalies. Initial genetic of analysis HH began with syndromic HH, where germline inherited or de novo variants in GLI3, encoding a central transcription factor in the sonic hedgehog (Shh) signalling pathway, were identified in most individuals with PHS. Following these discoveries in syndromic HH, the hypothesis that post-zygotic mosaicism in related genes may underly non-syndromic HH was tested. We discuss the identified mosaic variants within individuals with non-syndromic HH, review the analytical methodologies and diagnostic yields, and explore understanding of the functional role of the implicated genes with respect to Shh signalling, and cilia development and function. We also outline future challenges in studying non-syndromic HH and suggest potential novel strategies to interrogate brain mosaicism in HH.

Long term outcome after surgical treatment for hypothalamic hamartoma

PURPOSE

To determine long-term outcome for seizure control and clinical predictors for seizure freedom in patients undergoing surgical treatment for epilepsy associated with hypothalamic hamartoma (HH).

METHODS

155 patients underwent surgical treatment for HHs and treatment-resistant epilepsy at one center (Barrow Neurological Institute at St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA) between February 2003 and June 2010. Data collection included medical record review and direct follow-up interviews to determine seizure outcome. Statistical analysis included descriptive summaries of patient characteristics and time-to-event analysis for seizure freedom.

RESULTS

Long-term survival with follow-up of at least five years since first surgical treatment was available for 108 patients (69.7% of the treatment cohort). The surgical approach for first HH intervention consisted of transventricular endoscopic resection (n = 57; 52.8%), transcallosal interforniceal resection (n = 35; 32.4%), pterional resection (n = 7; 6.5%), and gamma knife radiosurgery (n = 9; 8.3%). Multiple surgical procedures were required for 39 patients (36.1%). There were 10 known deaths from all causes in the treatment cohort (6.5%). Of these, one (0.6%) was related to immediate complications of HH surgery, three (1.9%) were attributed to Sudden Unexpected Death in Epileptic Persons (SUDEP), and one (0.6%) to complications of status epilepticus. For surviving patients with long-term follow-up, 55 (50.9%) were seizure-free for all seizure types. Univariable analysis showed that seizure-freedom was related to 1) absence of a pre-operative history for central precocious puberty (p = 0.01), and 2) higher percentage of HH lesion disconnection after surgery (p = 0.047). Kaplan-Meier survival analysis shows that long-term seizure outcome following HH surgery is comparable to short-term results.

SUMMARY

These uncontrolled observational results show that long-term seizure control following HH surgical treatment is comparable to other forms of epilepsy surgery. Late relapse (at least one year after surgery) and SUDEP do occur, but in a relatively small number of treated patients. These results inform clinical practice and serve as a comparable benchmark for newer technologies for HH surgery, such as magnetic resonance imaging-guided laser interstitial thermal therapy, where long-term outcome results are not yet available.

Mosaic variants detectable in blood extend the clinicogenetic spectrum of GLI3-related hypothalamic hamartoma

Purpose

Hypothalamic hamartoma (HH) can be syndromic (eg, Pallister-Hall syndrome [PHS], HH, and mesoaxial polydactyly) or nonsyndromic. Most PHS cases have germline variants in GLI3, but a minority remain unresolved. Some nonsyndromic HH cases have GLI3 mosaic variants in the brain. PHS and nonsyndromic HH are regarded as 2 separate GLI3-related disorders, clinically and genetically. Here, we searched for mosaic variants in unsolved cases.

Methods

High-depth exome sequencing was performed on leukocyte-derived DNA in 1 unsolved PHS and 25 nonsyndromic HH cases. We searched for mosaic variants in GLI3 and other HH-associated genes. Mosaic variants were confirmed by droplet-digital polymerase chain reaction.

Results

The PHS case had a GLI3 stop-gain variant c.2845G>T; p.(Glu949Ter) at 6.9% variant allele fraction (VAF). Two nonsyndromic cases had GLI3 variants-a stop-gain (c.2639C>A; p.(Ser880Ter), VAF 3.7%) and a frameshift (c.3326_3330del; p.(Glu1109AlafsTer18), VAF 7.8%). The nonsyndromic patient with 3.7% VAF in blood had 35.8% VAF in HH tissue. He had a vestigial extra digit removed adjacent to his left fifth finger.

Conclusion

GLI3 mosaicism is associated with a phenotypic spectrum from PHS to HH with subtle extra PHS features, to isolated nonsyndromic HH. High-depth sequencing permits detection of low-level mosaicism, which is an important cause of both syndromic and nonsyndromic HH.

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

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

Hypothalamic hamartoma associated with polymicrogyria and periventricular nodular heterotopia in children: report of three cases and discussion of the origin of the seizures

PURPOSE

Hypothalamic hamartomas (HH) are malformations responsible for drug-resistant epilepsy. HH are usually isolated or part of a genetic syndrome, such as Pallister-Hall. Exceptionally they can be associated with other brain malformations such as polymicrogyria (PMG) and periventricular nodular heterotopia (PNH). We discuss the origin of the seizures associated with this combination of malformations, through electrophysiological studies, and review the literature on this rarely reported syndrome.

METHODS

We retrospectively reviewed the patients with HH who had surgery between 1998 and 2020 and selected those with associated focal PMG and PNH, detected on MRIs. All patients had comprehensive clinical evaluation and surface video-EEG and one underwent stereoelectroencephalography (SEEG).

RESULTS

Three male patients out of 182 were identified with a mean age at surgery of 7.5 years. MRI showed unilateral focal PMG (fronto-insulo-parietal, fronto-insulo-parieto-opercular, and fronto-insular, respectively) and multiple PNH homolateral to the main HH implantation side. In two patients, there were strong clinical and scalp EEG arguments for seizure onset within the HH. In the third, due to abnormalities on scalp video-EEG in the same area as PMG and the lack of gelastic seizures, SEEG was indicated and demonstrated seizure onset within the hamartoma. With a mean follow-up of 6 years, two patients were seizure-free.

CONCLUSION

Our results show that HH is the trigger of epilepsy, which confirms the high epileptogenic potential of this malformation. In patients such as ours, as in those with isolated HH, we recommend to begin by operating the HH independently of seizure semiology or electrophysiological abnormalities.

Image-guided LINAC radiosurgery in hypothalamic hamartomas

Introduction

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

Materials and methods

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

Results

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

Conclusions

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

Robot-assisted, real-time, MRI-guided laser interstitial thermal therapy for pediatric patients with hypothalamic hamartoma: surgical technique, pitfalls, and initial results

OBJECTIVE

Real-time, MRI-guided laser interstitial thermal therapy (MRgLITT) has been reported as a safe and effective technique for the treatment of epileptogenic foci in children and adults. After the recent approval of MRgLITT by the European Medicines Agency in April 2018, the authors began to use it for the treatment of hypothalamic hamartomas (HHs) in pediatric patients with the assistance of a robotic arm. In this study, the authors report their initial experience describing the surgical technique, accuracy of the robotic arm, safety, and efficacy.

METHODS

The laser fiber was placed with the assistance of the stereotactic robotic arm. The accuracy of the robotic arm for this procedure was calculated by comparing the intraoperative MRI to the preoperative plan. Common demographic and seizure characteristics of the patients, laser ablation details, complications, and short-term seizure outcomes were prospectively collected.

RESULTS

Sixteen procedures (11 first ablations and 5 reablations) were performed in 11 patients between 15 months and 17 years of age (mean age 6.4 years) with drug-resistant epilepsy related to HHs. The mean target point localization error was 1.69 mm. No laser fiber needed to be repositioned. The mean laser power used per procedure was 4.29 W. The trajectory of the laser fiber was accidentally ablated in 2 patients, provoking transient hemiparesis in one of these patients. One patient experienced postoperative somnolence and syndrome of inappropriate antidiuretic hormone secretion, and 2 patients had transient oculomotor (cranial nerve III) palsy. Fifty-four percent of the patients were seizure free after the first ablation (mean follow-up 22 months, range 15-33 months). All 5 patients who experienced an epilepsy relapse underwent a second treatment, and 4 remain seizure free at least 5 months after reablation.

CONCLUSIONS

In the authors' experience, the robotic arm was sufficiently accurate for laser fiber insertion, even in very young patients. MRgLITT appears to be an effective treatment for selected cases of HH. MRgLITT for HH is a minimally invasive procedure with appealing safety features, as it allows delivery of energy precisely under real-time MRI control. Nonetheless, complications may occur, especially in voluminous HHs. The amount of delivered energy and the catheter cooling system must be closely monitored during the procedure. A larger sample size and longer follow-up duration are needed to judge the efficacy and safety of MRgLITT for HH more rigorously. This initial experience was very promising.

[Surgical treatment of epilepsy in patients with hypothalamic hamartomas]

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

CONCLUSION

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

Hypothalamic Hamartomas: Evolving Understanding and Management

Hypothalamic hamartomas (HH) are rare, basilar developmental lesions with widespread comorbidities often associated with refractory epilepsy and encephalopathy. Imaging advances allow for early, even prenatal, detection. Genetic studies suggest mutations in GLI3 and other patterning genes are involved in HH pathogenesis. About 50%-80% of children with HH have severe rage and aggression and a majority of patients exhibit externalizing disorders. Behavioral disruption and intellectual disability may predate epilepsy. Neuropsychological, sleep, and endocrine disorders are typical. The purpose of this article is to provide a summary of the current understanding of HH and to highlight opportunities for future research.

Long-term cognitive outcome after radiosurgery in epileptic hypothalamic hamartomas and review of the literature

OBJECTIVE

Epileptic patients with hypothalamic hamartoma (HH) frequently present cognitive impairments. Surgical techniques aiming at HH can be very efficient for epilepsy relief and cognitive improvement but are also demonstrated to carry a significant risk of additional reduction in memory function in these already disabled patients. Gamma knife radiosurgery (GKS) offers an efficient minimally invasive procedure. We evaluated the effect of stereotactic radiosurgery on cognitive outcome.

METHODS

We designed a prospective single-center case series study. Thirty-nine epileptic patients (median age = 17 years, range = 4-50) with HH underwent preoperative and postoperative testing of intelligence quotient (IQ; all patients), including a working memory component, and other memory function testing (for patients ≥16 years old). All patients were prospectively evaluated and underwent complete presurgical and postsurgical clinical, electrophysiological, endocrinal, and visual assessments. In all patients, the postoperative assessment was performed at least 3 years after radiosurgery. We explored what variables correlate with cognitive outcome. Literature review was done for other surgical techniques and their risks for cognitive complications after surgery.

RESULTS

No decline was observed in intellectual ability (including working memory) after GKS, and no memory decline was seen in adults. We observed significant improvement (>1 SD in z-score) in working memory index (46%) and processing speed index (35%), as well as improvement in full-scale IQ (24%), verbal comprehension index (11%), perceptual organization index (21%), verbal learning (20%), and visual learning (33%). Before GKS, the probability of seizure cessation was higher in patients with higher cognitive performance. After GKS, the cognitive improvement was significantly higher in the seizure-free patients compared to the non-seizure-free patients.

SIGNIFICANCE

We found clear cognitive improvement in a high percentage of patients but importantly no significant decline in intellectual ability (including working memory) and no decline in memory in adult patients 3 years after GKS. GKS compares favorably to the other surgical techniques in terms of cognitive outcome, with similar seizure freedom.

Surgical targeting of large hypothalamic hamartomas and seizure-freedom following MR-guided laser interstitial thermal therapy

BACKGROUND

Large hypothalamic hamartomas (HH) are often associated with difficult-to-treat, refractory seizures. Although magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) has emerged as a useful tool to treat these challenging lesions, postoperative outcomes are variable and potentially related to differences in surgical targeting.

PURPOSE

We sought to identify differences in the anatomic localization of laser ablations that either did or did not result in seizure freedom.

METHODS

Four children who underwent MRgLITT for large HH (3 seizure-free and 1 not seizure-free) were included in the analysis. Ablation volumes were segmented, normalized, and overlaid on a high-resolution hypothalamic atlas. For each lesion, the size, spatial extent, and degree of overlap with key hypothalamic nuclei and surrounding brain regions were computed and compared between ablations that did and did not result in seizure freedom.

RESULTS

Ablation masks that resulted in seizure freedom were smaller and located more centrally than the ablation mask that did not. In addition, ablation masks that resulted in seizure freedom overlapped with regions including the paraventricular nucleus, the posterior hypothalamus and the zona incerta, fornix, and mammillothalamic tract, whereas the single non-seizure-free ablation did not.

CONCLUSION

Differences in the size, position, and anatomical localization of ablation volumes may be a potential contributor to the variability in postoperative outcomes of large HH treated with MRgLITT. A novel, high-resolution MRI atlas of the hypothalamus identifies a number of regions at the interface of large HH that are preferentially disconnected in seizure-free patients. This method of anatomical localization not only serves as a potential clinical tool for surgical targeting but may also provide novel insights into the mechanisms of epileptogenesis in hypothalamic hamartomas.

Seizure Semiology in Focal and Generalized Epilepsies: Distinctive and Overlapping Features

Studying seizure semiology is the first step in evaluating any patient with epilepsy which leads the way to further investigations and management, particularly in differentiating focal and generalized epilepsies. While the usefulness of semiological analysis has been confirmed through decades' worth of research and clinical practice, there remains some instances when the line between focal and generalized semiological features is blurred leading to difficulties identifying the type of epilepsy at hand. This in turn can lead to delayed or wrong diagnoses with significant implications.In this review article, we explain the role of semiology in epilepsy, specifically in differentiating focal versus generalized epilepsies and cover the semiological features for both groups. We also discuss the occasional overlapping semiology between the two groups and provide case examples.

Gelastic seizures and the hypothalamic hamartoma syndrome: Epileptogenesis beyond the lesion?

The clinicoradiologic syndrome of hypothalamic hamartoma (HH) manifests with a variety of symptoms, including pharmacoresistant epilepsy with multiple seizure types, precocious puberty, behavioral disturbances, and cognitive impairment. Gelastic seizures are an early marker of epilepsy with HH in most of the cases. Despite a high variability, two major epilepsy phenotypes can be distinguished, based on electroclinical features: (i) focal seizures with epigastric or déjà-vu aura, loss of consciousness, and oroalimentary or gestural automatisms suggestive of temporal lobe involvement; and (ii) motor seizures with tonic, atonic, myoclonic, or versive phenomena, suggesting frontoparietal network involvement, with possible evolution toward an epileptic encephalopathy. The underlying physiopathologic mechanisms are not completely elucidated. The well-known intrinsic epileptogenicity of the HH represents the rationale for direct HH-aiming surgical procedures, with variable success in achieving seizure freedom. The concept of kindling-like secondary epileptogenesis has been suggested as a possible putative mechanism since the very beginnings of the hamartocentric era. Accordingly, a cortical area with enhanced epileptogenic properties due to an independent stage of secondary epileptogenesis would be responsible for seizures persisting after hamartoma ablation. However, recent intracerebral stereotactic EEG (SEEG) explorations demonstrated more complex, both reciprocal and hierarchical, relationships within the hypothalamo-cortical epileptogenic networks. Network formation may be due to either secondary epileptogenesis or widespread epileptogenicity present at the outset. A short time window from epilepsy onset to surgery seems to be crucial to cure epilepsy by direct surgery addressing a hamartoma. SEEG exploration may be reasonably proposed in cases where clinical data suggest an extension of the epileptogenic zone outside the limits of the HH, especially in focal seizures with impaired awareness and absence of gelastic seizures, or after a failure of the direct HH-aiming procedure.

Ecstatic and gelastic seizures related to the hypothalamus

Ecstatic seizures constitute a rare form of epilepsy, and the semiology is diverse. Previously, brain areas including the temporal lobe and the insula have been identified to be involved in clinical expression. The aim of this report is to review changes in ecstatic seizures in a patient before and after operation for a hypothalamic hamartoma, and to scrutinize the relation to gelastic seizures. In this case, the ecstatic seizures disappeared after surgery of the hamartoma but reappeared eleven years later. Clinical information was retrospectively obtained from medical records, interviews, and a questionnaire covering seizure semiology that pertained to ecstatic and gelastic seizures. Our findings imply a possible connection between gelastic and ecstatic seizures, originating from a hypothalamic hamartoma. To our knowledge, this location has not previously been described in ecstatic seizures. Gelastic seizures may in this case be associated with ecstatic seizures. We speculate that patients with ecstatic seizures may have an ictal activation of neuronal networks that involve the insula. Our case may add information to the knowledge concerning ecstatic seizures.

Distinguishing Dependent-Stage Secondary Epileptogenesis in a Complex Case of Giant Hypothalamic Hamartoma With Assistance of a Computational Method

Besides gelastic seizures, hypothalamic hamartoma (HH) is also noted for its susceptibility to remote secondary epileptogenesis. Although clinical observations have demonstrated its existence, and a three-stage theory has been proposed, how to determine whether a remote symptom is spontaneous or dependent on epileptic activities of HH is difficult in some cases. Herein, we report a case of new non-gelastic seizures in a 9-year-old female associated with a postoperatively remaining HH. Electrophysiological examinations and stereo-electroencephalography (SEEG) demonstrated seizure onsets with slow-wave and fast activities on the outside of the HH. By using computational methodologies to calculate the network dynamic effective connectivities, the importance of HH in the epileptic network was revealed. After SEEG-guided thermal coagulation of the remaining HH, the patient finally was seizure-free at the 2-year follow-up. This case showed the ability of computational methods to reveal information underlying complex SEEG signals, and further demonstrated the dependent-stage secondary epileptogenesis, which has been rarely reported.

Ecstatic and gelastic seizures relate to the hypothalamus

Ecstatic seizures constitute a rare form of epilepsy, and the semiology is diverse. Previously, brain areas including the temporal lobe and the insula have been identified to be involved in clinical expression. The aim of this report is to review changes in ecstatic seizures in a patient before and after operation of a hypothalamic hamartoma, and to scrutinize the relation to gelastic seizures. In this case, the ecstatic seizures disappeared after surgery of the hamartoma but reappeared eleven years later. Clinical information was retrospectively obtained from medical records, interviews, and a questionnaire covering seizure semiology that pertained to ecstatic and gelastic seizures. Our findings imply a possible connection between gelastic and ecstatic seizures, originating from a hypothalamic hamartoma. To our knowledge, this location has not previously been described in ecstatic seizures. Gelastic seizures may in this case were associated with ecstatic seizures. We speclate patients with ecstatic seizures may have an ictal activation of neuronal networks that involves the insula. Our case may add information to the growing knowledge concerning ecstatic seizures.

Electrophysiological properties and seizure networks in hypothalamic hamartoma

Objective

Little is known about the intrinsic electrophysiological properties of hypothalamic hamartoma (HH) in vivo and seizure network since only few cases using stereoelectroencephalography (SEEG) electrodes exploring both cortex and HH have been published. To elucidate these issues, we analyzed simultaneous SEEG recordings in HH and cortex systematically.

Methods

We retrospectively investigated data from 15 consecutive patients with SEEG electrodes into the HH for the treatment purpose of radiofrequency thermocoagulation treatment. Additional SEEG electrodes were placed into the cortex in 11 patients to assess extra‐HH involvement. Interictal discharges within the HH and anatomo‐electroclinical correlations during seizures of each patient were qualitatively and quantitatively analyzed.

Results

Overall, 77 electrodes with 719 contacts were implanted, and 33 spontaneous seizures were recorded during long‐term SEEG monitoring. Interictally, distinct electrophysiological patterns, including isolated intermittent spikes/sharp waves, burst spike and wave trains, paroxysmal fast discharges, periodic discharges, and high‐frequency oscillations, were identified within the HH. Notably, synchronized or independent interictal discharges in the cortex were observed. Regarding the ictal discharges, the electrical onset pattern within the HH always started with abrupt giant shifts superimposed on low‐voltage fast activity across patients. The gelastic seizure network mainly involved the HH, orbitofrontal areas, and cingulate gyrus. Seizures with automatisms and impaired awareness primarily propagated to mesial temporal lobes. Moreover, independent ictal discharges arising from the mesial temporal lobe were detected in three out of nine patients.

Interpretation

This study comprehensively reveals intrinsic electrophysiological patterns and epileptogenic networks in vivo, providing new insights into the mechanisms underlying cortical and subcortical epileptogenesis.

Repeat stereotactic radiofrequency thermocoagulation in patients with hypothalamic hamartoma and seizure recurrence

Objective

To evaluate the feasibility of repeat stereotactic radiofrequency thermocoagulation (re‐SRT) for patients with hypothalamic hamartoma (HH) and to clarify clinical and surgical factors for seizure outcomes.

Methods

Hypothalamic hamartoma patients with gelastic seizures (GSs) who underwent SRT were retrospectively reviewed. Seizure outcomes were evaluated separately for GS and other types of seizures (non‐GS). Surgical complications were compared between re‐SRT and first SRT. Clinical and surgical factors related to both seizure recurrences after first SRT and final seizure outcomes were analyzed.

Results

Participants comprised 150 patients (92 males; median age at surgery, 8 years; range, 1.7‐50 years). Of those, 122 (81.3%) had non‐GS. Forty‐three patients (28.7%) underwent re‐SRT. Freedom from GS was achieved by first SRT in 103 patients (68.7%), second SRT in 30/40 (67.5%), third SRT in 3/10 (30.0%), and fourth SRT in 2/3 (66.7%). Finally, 135 patients (90.0%) became GS‐free. Ninety patients (73.8%) achieved non‐GS freedom, with first SRT in all except one case. Transient complications were more frequent with first SRT (118/150, 78.7%) than re‐SRT (35/56, 62.5%), whereas persistent complications were more frequent with re‐SRT (7/56, 12.5%) than with first SRT (3/150, 2.0%). Multivariate analyses revealed only younger age at surgery (≤1 year) as related to GS recurrence after first SRT, with no variables affecting final GS outcomes. Meanwhile, seizure type (tonic seizure), intellectual disability, and genetic syndromes were significant factors for both non‐GS recurrence and final outcomes. Multiple previous treatments were significantly related to final non‐GS outcomes as well. Size and subtype of HH and surgical factors were unrelated to seizure outcomes.

Significance

Repeat stereotactic radiofrequency thermocoagulation provides potential opportunities to achieve freedom from recurrent GS, albeit with increased risks of persistent complications. Non‐GS and intellectual disability could offer early surgical indications, and repeated ineffective treatments should be avoided.

Long-term use of methylphenidate in a boy with hypothalamic tumor, drug-resistant epilepsy and ADHD

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We report the successful treatment of a boy with hypothalamic tumor, gelastic seizures, drug-resistant epilepsy and ADHD

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The use of methylphenidate significantly reduced symptoms of ADHD while seizure frequency remained unchanged.

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

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

Surgical treatment for refractory epilepsy

The goal of any epilepsy surgery is to improve patient's quality of life by achieving seizure freedom or by reducing the frequency of severely debilitating seizures. To achieve this goal, non-invasive and invasive diagnostic methods must precisely delineate the epileptogenic zone (EZ), which is defined as the area that needs to be resected to obtain seizure freedom. At the same time, the correct identification of eloquent brain areas is inevitable to avoid new neurological deficits from surgery. In recent years, the technical advances in diagnostics have enabled us to achieve these goals in an increasing number of cases. As a consequence, and with new surgical treatment options available, the number of patients who might benefit from epilepsy surgery is constantly increasing. Especially in pediatric epilepsy, early surgical intervention is becoming frequently advocated as it has been shown to improve cognitive and behavioral outcome. Specialized epilepsy centers and multidisciplinary teams are required to provide adequate care and treatment. The goal of this review is to describe important diseases that are accessible to epilepsy surgery and to give an overview of current diagnostic methods. The focus lies on established as well as novel techniques in epilepsy surgery. The presurgical work-up and patient selection is outlined.

A novel use of the NeuroBlate SideFire probe for minimally invasive disconnection of a hypothalamic hamartoma in a child with gelastic seizures

The authors describe the case of a 22-month-old boy who presented with gelastic seizures and developmental delay. Magnetic resonance imaging and video-electroencephalography monitoring revealed a primarily intraventricular hypothalamic hamartoma and gelastic seizures occurring 20-30 times daily. The patient was treated with various regimens of antiepileptic medications for 16 months, but the seizures remained medically intractable. At 3 years of age, he underwent stereotactic laser ablation with an aim of disconnection of the lesion. The procedure was performed with the NeuroBlate SideFire probe. To the authors' knowledge, this is the first reported use of this technology for this procedure and serves as proof of concept. There were no perioperative complications, and 2 years postprocedure, the patient remains seizure free with marked behavioral and cognitive improvements.

A case of pure gelastic seizures due to hypothalamic hamartoma with a benign course

Hypothalamic hamartoma is a potentially complex entity with diverse clinical manifestations. We report a case of gelastic seizures associated with a hypothalamic hamartoma, which followed a benign course. A 31-year-old woman with episodes of laughter was referred for diagnostic evaluation. Her initial MRI and EEG were reported as normal. However, her episodes of laughter were typical of gelastic seizures from history and video review. Repeat MRI revealed a small HH. She declined any medical treatment and was medication free until last follow-up. This benign course of HH-associated epilepsy, not necessitating treatment, to our knowledge, has not been previously reported.

Endoscopic Treatment of Hypothalamic Hamartomas

Hypothalamic hamartoma (HH) is a benign indolent lesion despite the presentation of refractory epilepsy. Behavioral disturbances and endocrine problems are additional critical symptoms that arise along with HHs. Due to its nature of generating epileptiform discharge and spreading to cortical region, various management strategies have been proposed and combined. Surgical approaches with open craniotomy or endoscopy, stereotactic approaches with radiosurgery and gamma knife surgery or radiofrequency thermos-coagulation, and laser ablation have been introduced. Topographical dimension and the surgeon’s preference are key factors for treatment modalities. Endoscopic disconnection has been one of the most favorable options performed in treating HHs. Here we discuss presurgical evaluation, patient selection, surgical procedures, and complications.

Pure endoscopic management of epileptogenic hypothalamic hamartomas

Hypothalamic hamartomas (HH) are rare congenital malformations located in the region of the tuber cinereum and third ventricle. Their usual clinical presentation is characterized by gelastic/dacrystic seizures which often become pharmaco-resistant and progress to secondary focal/generalized intractable epilepsy causing mostly in children cognitive and behavioral problems (particularly in cases of progressive epileptic encephalopathy) and precocious puberty. Whereas gelastic seizures can be surgically controlled either by resection of the lesion or disconnection (tissue-destructive) procedures, aimed at functionally prevent the spreading of the epileptic burst; generalized seizures tend to respond better to HH excision rather than isolated neocortical resections, which generally fail to control them. Prospective analysis of 14 consecutive patients harboring HH treated in an 8-year period; 12 patients had unilateral and two bilateral HH. All patients were managed by pure endoscopic excision of the HH. The mean operative time was 48 min and mean hospital stay was 2 days; perioperative blood loss was negligible in all cases. Two patients showed a transient diabetes insipidus (DI); no transient or permanent postoperative neurological deficit or memory impairment was recorded. Complete HH excision was achieved in 10/14 patients. At a mean follow-up of 48 months, no wound infection, meningitis, postoperative hydrocephalus, and/or mortality were recorded in this series of patients. Eight patients became seizure free (Engel class I), 2 other experienced worthwhile improvement of disabling seizures (Engel class II); 2 patients were cured from gelastic attacks while still experiencing focal dyscognitive seizures; and 2, having bilateral HH (both undergoing unilateral HH excision), did not experience significant improvement and required later on a temporal lobectomy coupled to amygdalohyppocampectomy. Overall, the followings resulted to be predictive factors for better outcomes in terms of seizure control: (1) cases of unilateral, Delalande class B, HH, (2) shorter history of epilepsy. Endoscopic resection of HH proved, in our series, to be effective in achieving complete control or in reducing the frequency of seizures. Furthermore, this approach has confirmed its minimally invasive nature with a very low morbidity rate: of note, it allowed to better preserve short-term memory and hypothalamic function.

Stereotactic radiofrequency thermocoagulation for giant hypothalamic hamartoma

OBJECTIVE

The authors undertook this study to validate the feasibility and safety of stereotactic radiofrequency thermocoagulation (SRT) for the surgical treatment of giant hypothalamic hamartoma (HH).

METHODS

Of the 109 patients who underwent SRT for hypothalamic hamartoma (HH) at the authors' institution between 1997 and 2013, 16 patients (9 female, 7 male) had giant HHs (maximum diameter ≥ 30 mm). The clinical records of these 16 patients were retrospectively reviewed.

RESULTS

The patients' age at first SRT ranged from 1 to 22 years (median 5 years). The maximum diameter of their HHs was 30–80 mm (mean 38.5 mm). Eleven HHs had bilateral attachments to the hypothalamus. All patients had gelastic seizures (GS), and 12 had types of seizures other than GS. Some of these patients also had mental retardation (n = 10, 62.5%), behavioral disorders (n = 8, 50.0%), and precocious puberty (n = 11, 68.8%). A total of 22 SRT procedures were performed; 5 patients underwent repeat SRT procedures. There was no mortality or permanent morbidity. After 17 of the 22 procedures, the patients experienced transient complications, including high fever (n = 7), hyperphagia (n = 3), hyponatremia (n = 6), disturbance of consciousness (n = 1), cyst enlargement (n = 1), and epidural hematoma (n = 1). Thirteen patients (81.3%) achieved freedom from GS after the final SRT procedure during a follow-up period ranging from 6 to 60 months (mean 23 months). Twelve patients had nongelastic seizures in addition to GS, and 7 (58.3%) of these 12 patients experienced freedom from their nongelastic seizures.

CONCLUSIONS

SRT provided minimal invasiveness and excellent seizure outcomes even in patients with giant HHs. Repeat SRT is safe for residual GS. SRT is a feasible single surgical strategy for HH regardless of the tumor's size or shape.

Mutations of the Sonic Hedgehog Pathway Underlie Hypothalamic Hamartoma with Gelastic Epilepsy

Hypothalamic hamartoma (HH) with gelastic epilepsy is a well-recognized drug-resistant epilepsy syndrome of early life.(1) Surgical resection allows limited access to the small deep-seated lesions that cause the disease. Here, we report the results of a search for somatic mutations in paired hamartoma- and leukocyte-derived DNA samples from 38 individuals which we conducted by using whole-exome sequencing (WES), chromosomal microarray (CMA), and targeted resequencing (TRS) of candidate genes. Somatic mutations were identified in genes involving regulation of the sonic hedgehog (Shh) pathway in 14/38 individuals (37%). Three individuals had somatic mutations in PRKACA, which encodes a cAMP-dependent protein kinase that acts as a repressor protein in the Shh pathway, and four subjects had somatic mutations in GLI3, an Shh pathway gene associated with HH. In seven other individuals, we identified two recurrent and three single brain-tissue-specific, large copy-number or loss-of-heterozygosity (LOH) variants involving multiple Shh genes, as well as other genes without an obvious biological link to the Shh pathway. The Shh pathway genes in these large somatic lesions include the ligand itself (SHH and IHH), the receptor SMO, and several other Shh downstream pathway members, including CREBBP and GLI2. Taken together, our data implicate perturbation of the Shh pathway in at least 37% of individuals with the HH epilepsy syndrome, consistent with the concept of a developmental pathway brain disease.

MRI-guided stereotactic radiofrequency thermocoagulation for 100 hypothalamic hamartomas

OBJECT

The aim of this study was to elucidate the invasiveness, effectiveness, and feasibility of MRI-guided stereotactic radiofrequency thermocoagulation (SRT) for hypothalamic hamartoma (HH).

METHODS

The authors examined the clinical records of 100 consecutive patients (66 male and 34 female) with intractable gelastic seizures (GS) caused by HH, who underwent SRT as a sole surgical treatment between 1997 and 2013.

The median duration of follow-up was 3 years (range 1–17 years). Seventy cases involved pediatric patients. Ninety percent of patients also had other types of seizures (non-GS). The maximum diameter of the HHs ranged from 5 to 80 mm (median 15 mm), and 15 of the tumors were giant HHs with a diameter of 30 mm or more. Comorbidities included precocious puberty (33.0%), behavioral disorder (49.0%), and mental retardation (50.0%).

RESULTS

A total of 140 SRT procedures were performed. There was no adaptive restriction for the giant or the subtype of HH, regardless of any prior history of surgical treatment or comorbidities. Patients in this case series exhibited delayed precocious puberty (9.0%), pituitary dysfunction (2.0%), and weight gain (7.0%), besides the transient hypothalamic symptoms after SRT. Freedom from GS was achieved in 86.0% of patients, freedom from other types of seizures in 78.9%, and freedom from all seizures in 71.0%. Repeat surgeries were not effective for non-GS. Seizure freedom led to disappearance of behavioral disorders and to intellectual improvement.

CONCLUSIONS

The present SRT procedure is a minimally invasive and highly effective surgical procedure without adaptive limitations. SRT involves only a single surgical procedure appropriate for all forms of epileptogenic HH and should be considered in patients with an early history of GS.

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.

Gelastic epilepsy: Beyond hypothalamic hamartomas

Gelastic epilepsy or laughing seizures have been historically related to children with hypothalamic hamartomas. We report three adult patients who had gelastic epilepsy, defined as the presence of seizures with a prominent laugh component, including brain imaging, surface/invasive electroencephalography, positron emission tomography, and medical/surgical outcomes. None of the patients had hamartoma or other hypothalamic lesion. Two patients were classified as having refractory epilepsy (one had biopsy-proven neurocysticercosis and the other one hippocampal sclerosis and temporal cortical dysplasia). The third patient had no lesion on MRI and had complete control with carbamazepine. Both lesional patients underwent resective surgery, one with complete seizure control and the other one with poor outcome. Although hypothalamic hamartomas should always be ruled out in patients with gelastic epilepsy, laughing seizures can also arise from frontal and temporal lobe foci, which can be surgically removed. In addition, we present the first case of gelastic epilepsy due to neurocysticercosis.

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.

Risk of seizures in children with tectal gliomas

The objective of this study was to determine the prevalence of seizures in children with tectal gliomas and to determine if there are common clinical, electroencephalography (EEG), or radiologic findings that predict risk of seizures in these patients. We conducted a retrospective review of all patients with tectal gliomas over a 22-year period at a single institution. Data extraction included sex, age at presentation of tectal glioma and age of presentation with seizures, magnetic resonance imaging (MRI) findings, seizure frequency and semiology, and EEG findings. We identified 79 patients, 66 of whom had adequate imaging and clinical data for further analysis. Eight patients (12.1%) had a history of seizures. Three patients had a clear symptomatic cause of seizures. Three patients were diagnosed with a tectal glioma as an incidental finding after a first seizure. One patient had a history of febrile convulsions. One patient had a generalized seizure 5 years after presenting with macrocephaly. Although the risk of seizure in children with known tectal glioma was relatively high, we did not identify specific clinical, radiologic, EEG, or MRI features that are predictive of increased risk. Thus, in children with tectal gliomas who have seizures, alternative causes for the seizures must be sought.