Selective surgical mamillo-thalamic tract disconnection in hypothalamic hamartoma results in complete disappearance of gelastic seizures.

Hypothalamic hamartoma is a less common condition characterized by the several types of epileptic seizures including the gelastic type. It is reported that gelastic seizures are resistant to medical treatment with anticonvulsants, while stereotactic thermocoagulation or Gamma Knife radiosurgery are effective for seizure control. Here, we report an individual case where direct surgical resection disconnecting hypothalamic hamartoma from mammillothalamic tract resulted in complete disappearance of gelastic seizures without deterioration of cognitive function. A 6-year-old boy developed gelastic seizures at the age of 2 and suffered from precocious puberty. Anticonvulsants including carbamazepine and zonisamide failed to control seizures. The patient underwent direct division of the mammillothalmic tract by removal of hypothalamic hamartoma partially via anterior interhemispheric approach. It was observed that gelastic seizures disappeared completely after the surgical treatment without any endocrine and cognitive dysfunction for a follow-up period of 14 years. The mammillothalamic tract which connects anterior nucleus of thalamus and mammillary bodies plays a key role in gelastic seizures related to hypothalamic hamartoma. In this case, we disconnected the hamartoma specifically from the mammillary bodies and not from the rest of hypothalamus. Effectively, it enabled permanent control of seizures. This result shows that fibers connecting other hypothalamic structures and the dorsomedial nucleus of thalamus are not involved in gelastic seizure propagation from the hypothalamic hamartoma. When surgical treatment of hypothalamic hamartomas is performed it has high morbidity associated with hypothalamic disorders. Therefore, disconnection between hypothalamic hamartoma and mammillary bodies presents a possibility of reducing hypothalamic damage. Surgical disconnection between hamartoma and mammillothalamic tract carries minimal hypothalamic injury risk and our results suggest that it has the potential of seizure control for intractable gelastic seizures with less complications.

Surgical treatment of hypothalamic hamartomas.

Hypothalamic hamartomas are aberrant masses, composed of abnormally distributed neurons and glia. Along endocrine and cognitive symptoms, they may cause epileptic seizures, including the specific gelastic and dacrystic seizures. Surgery is the treatment of drug-resistant hamartoma epilepsy, with associated positive results on endocrine, psychiatric, and cognitive symptoms. Recently, alternatives to open microsurgical treatment have been proposed. We review these techniques and compare their efficacy and safety. Open resection or disconnection of the hamartoma, either through pterional, transcallosal, or transventricular approach, leads to good epileptological control, but its high complication rate, up to 30%, limits its indications. The purely cisternal peduncular forms remain the only indication of open, pterional approach, while other strategies have been developed to overcome the neurological, endocrine, behavioral, or cognitive complications. Laser and radiofrequency thermocoagulation-based disconnection through robot-guided stereo-endoscopy has been proposed as an alternative to open microsurgical resection and stereotactic destruction. The goal is to allow safe and complete disconnection of a possibly complex attachment zone, through a single intraparenchymal trajectory which allows multiple laser or radiofrequency probe trajectory inside the ventricle. The efficacy was high, with 78% of favorable outcome, and the overall complication rate was 8%. It was especially effective in patients with isolated gelastic seizures and pure intraventricular hamartomas. Stereotactic radiosurgery has proved as efficacious and safer than open microsurgery, with around 60% of seizure control and a very low complication rate. Multiple stereotactic thermocoagulation showed very interesting results with 71% of seizure freedom and 2% of permanent complications. Stereotactic laser interstitial thermotherapy (LiTT) seems as effective as open microsurgery (from 76 to 81% of seizure freedom) but causes up to 20% of permanent complications. This technique has however been highly improved by targeting only the epileptogenic onset zone in the hamartoma, as shown on preoperative functional MRI, leading to an improvement of epilepsy control by 45% (92% of seizure freedom) with no postoperative morbidity. All these results suggest that the impact of the surgical procedure does not depend on purely technical matters (laser vs radiofrequency thermocoagulation or stereotactic vs robot-guided stereo-endoscopy) but relies on the understanding of the epileptic network, including inside the hamartoma, the aim being to plan an effective disconnection or lesion of the epileptogenic part while sparing the adjacent functional structures.

Significance of the electrophysiological border between hypothalamic hamartomas and the hypothalamus for the target of ablation surgery identified by intraoperative semimicrorecording.

OBJECTIVE: Ablation surgery has become the first line of treatment for hypothalamic hamartomas (HHs). For effective treatment, optimum targeting of ablation is mandatory. The present study aimed to evaluate the correspondence between the electrophysiological features of HHs and morphological targeting by semimicrorecording during stereotactic radiofrequency thermocoagulation (SRT). METHODS: Eighty HH patients who underwent SRT were involved. Semimicrorecording was performed on the first trajectory. The distance from the center of the target at the morphological border (TMB) determined by magnetic resonance imaging, differences in discharge patterns, and area potentials (APs) were measured. RESULTS: The electrophysiological border (EB) between the HH and hypothalamus was detected by semimicrorecording in 73 (91.3%), AP increase (API) in the HH was detected in 31 (38.8%), and spike discharges (SDs) of the HH were detected in 56 patients (70.0%). Semimicrorecording showed significantly different APs among structures passing through the trajectory, except between API and SDs. The median distances from the center of the TMB to the EB, API, SDs, and AP decline were -3.50, -2.49, -1.38, and +2.00 mm, respectively. SIGNIFICANCE: The electrophysiological features of HHs were shown by semimicrorecording during SRT. The EB corresponded to the morphological border. The electrophysiologically active area of HHs was located near the border. Ablation surgery should focus on disconnection at the border between the HH and the hypothalamus to maximize its effectiveness, as well as to reduce complications.

Laser interstitial thermotherapy (LiTT) in pediatric epilepsy surgery.

Laser interstitial thermotherapy (LiTT) is a novel stereotactic approach to the surgical treatment of severe drug-resistant focal epilepsies. This review extends our recent general review on this topic (Hoppe et al. Laser interstitial thermotherapy [LiTT] in epilepsy surgery. Seizure 2017; 48:45-52) with a focus on children (age <18 years). A PubMed search retrieved 25 uncontrolled case series reports that included a total of 179 pediatric patients as well as 7 review papers that specifically referred to using LiTT in pediatric epilepsy surgery (due August 31, 2018). Hypothalamic hamartomas (HH) represented the most frequent indication (64.2%) while therapeutic evidence for other more frequent etiologies underlying severe focal childhood epilepsies (e.g. focal cortical dysplasia, mesiotemporal sclerosis) is still scarce (n<20). For the published cases, the rate of severe complications was 3.4% and the overall complication rate was 23.5%. The seizure freedom rate (Engel class 1) was 57.5% (including patients with early follow-up and repeat thermoablations). None of the studies included the systematic evaluation of the cognitive outcome. Overall, the published evidence does not yet allow a scientific or clinical judgement on the utility of LiTT for pediatric epilepsy surgery. LiTT is likely to extend the neurosurgical toolbox with regard to deep brain lesions (e.g. HH). However, in cases that are equally accessible for both approaches therapeutic superiority of LiTT over open resective surgery still remains to be demonstrated. Recommendations for controlled though non-randomized outcome studies are provided.

Nasopharyngeal glial heterotopia with delayed postoperative meningitis.

A male infant, who underwent radical resection of a large glial heterotopia at the nasopharynx at 8 days, developed delayed postoperative bacterial meningitis at 9 months. Neuroradiological examination clearly demonstrated that meningitis had occurred because of the intracranial and extracranial connections, which were scarcely seen in the perioperative period. A transsphenoidal extension of hypothalamic hamartoma is possible because the connection started from the right optic nerve, running through the transsphenoidal canal in the sphenoid bone and terminating at the recurrent mass in the nasopharyngeal region.

Clinical features and evolution of the gelastic seizures-hypothalamic hamartoma syndrome.

Gelastic seizures, usually with onset in early infancy, are the hallmark manifestation of hypothalamic hamartoma. This seizure type is directly generated by hamartoma itself, intrinsically epileptogenic because of its anatomofunctional organization. Other types of seizures, focal or generalized, may appear during the evolution, probably resulting from mechanisms of secondary epileptogenesis. Nevertheless, the clinical expression and the severity of the syndrome, ranging from a focal drug-resistant epilepsy to a catastrophic generalized encephalopathy with severe cognitive and behavioral impairments, depends on the size and the site of attachment of the hamartoma. Early suspicion, timely diagnosis, and appropriate treatment are mandatory to reverse a potential catastrophic evolution of this condition.

Hypothalamic hamartoma: Neuropathology and epileptogenesis.

Hypothalamic hamartomas (HHs) are congenital malformations of the ventral hypothalamus resulting in treatment-resistant epilepsy and are intrinsically epileptogenic for the gelastic seizures that are the hallmark symptom of this disorder. This paper reviews the neuropathologic features of HHs associated with epilepsy, with an emphasis on characterizing neuron phenotypes and an ultimate goal of understanding the cellular model of ictogenesis occurring locally within this tissue. We also present previously unpublished findings on Golgi staining of HH. The microarchitecture of HH is relatively simple, with nodular clusters of neurons that vary in size and abundance with poorly defined boundaries. Approximately 80-90% of HH neurons have an interneuron-like phenotype with small, round soma and short, unbranched processes that lack spines. These neurons express glutamic acid decarboxylase and likely utilize γ-aminobutyric acid (GABA) as their primary neurotransmitter. They have intrinsic membrane properties that lead to spontaneous pacemaker-like firing activity. The remaining HH neurons are large cells with pleomorphic, often pyramidal, soma and dendrites that are more likely to be branched and have spines. These neurons appear to be excitatory, projection-type neurons, and have the functionally immature behavior of depolarizing and firing in response to GABA ligands. We hypothesize that the irregular neuronal clusters are the functional unit for ictogenesis. Further research to define and characterize these local networks is required to fully understand the cellular mechanisms responsible for gelastic seizures.

Gelastic seizures: incidence, clinical and EEG features in adult patients undergoing video-EEG telemetry.

This study aimed to determine clinical features of adult patients with gelastic seizures recorded on video -electroencephalography (EEG) over a 5-year period. We screened video-EEG telemetry reports for the occurrence of the term "gelastic" seizures, and assessed the semiology, EEG features, and duration of those seizures. Gelastic seizures were identified in 19 (0.8%) of 2,446 admissions. The presumed epileptogenic zone was in the hypothalamus in one third of the cases, temporal lobe epilepsy was diagnosed in another third, and the remainder of the cases presenting with gelastic seizures were classified as frontal, parietal lobe epilepsy or remained undetermined or were multifocal. Gelastic seizures were embedded in a semiology, with part of the seizure showing features of automotor seizures. A small proportion of patients underwent epilepsy surgery. Outcome of epilepsy surgery was related to the underlying pathology; two patients with hippocampal sclerosis had good outcomes following temporal lobe resection and one of four patients with hypothalamic hamartomas undergoing gamma knife surgery had a good outcome.

Tracheal resection with patient under local anesthesia and conscious sedation.

The authors describe the case of a woman with a 2-year history of dyspnea and stridor caused by a tracheal hamartoma. The patient underwent tracheal resection and end-to-end anastomosis under monitored local anesthesia and conscious sedation, which was achieved by boluses of ketamine and midazolam. Local anesthesia was obtained by the use of stepwise local infiltration of 2% lidocaine and 7.5 mg/mL ropivacaine during the operation. The patient remained awake during the entire procedure, thus permitting the movement of the vocal cords to be monitored. Mechanical ventilation was never required. The postoperative period was uneventful, and the patient did not describe having any discomfort.

Treatment modalities for intractable epilepsy in hypothalamic hamartoma.

Hypothalamic hamartoma (HH) is usually associated with refractory epilepsy, cognitive impairment, and behavioral disturbance. There is now increasing evidence that HH can be treated effectively with a variety of neurosurgical approaches. Treatment options for intractable gelastic seizure in HH patients include direct open surgery with craniotomy, endoscopic surgery, radiosurgery with gamma knife (GKS) and stereotactic radiofrequency thermocoagulation. Selection of treatment modalities depends on type and size of the HH and the surgeon's preference. Two surgical techniques, resection and disconnection, had been described with favorable outcomes. Pretreatment evaluation, patient selection, surgical techniques, complications, and possible selection of treatment are discussed in this chapter.

Anatomic study of the lamina terminalis: neurosurgical relevance in approaching lesions within and around the third ventricle.

BACKGROUND: The lamina terminalis (LT) represents an important neurosurgical corridor by which to fenestrate the third ventricle into the subarachnoid space or to approach lesions of the third ventricle. However, a comprehensive review of its anatomy and approaches to it for various pathologies is lacking in the literature. We studied the anatomy of the LT in 21 cadavers and described the LT as observed in cadaveric dissections. We also reviewed the literature regarding the detailed anatomy and pathology of the LT. In addition, a case illustration that demonstrates the use of this structure as a corridor to third ventricular tumors is presented. Our aim was to explore the anatomy of the LT through cadaveric dissection, a review of the literature, and a case study. METHODS: Twenty-one adult cadaver heads underwent microdissection of the LT with a focus on the working distance available to enter the third ventricle and related vascular structures. RESULTS: Inferior to the anterior communicating artery was the safer region to open due to the lack of perforating arteries. A working distance of approximately 1 cm can be expected through the LT. CONCLUSIONS: This information may aid neurosurgeons during approaches through and around the LT.

Transendoscopic intraoperative recording of gelastic seizures from a hypothalamic hamartoma.

OBJECT: The differential diagnosis of hypothalamic masses in children includes hamartomas, which are associated with gelastic seizures and endocrine dysfunction. The purpose of this study was to utilize transendoscopic electroencephalography (EEG) recording at the time of tissue biopsy to further assist in diagnosis, determination of prognosis, and treatment planning. METHODS: We present the case of an infant with gelastic seizures and a large hypothalamic mass lesion. Despite a clinical and radiographic presentation typical of hypothalamic hamartoma (HH), slight growth on serial imaging raised concern for a diagnosis of intrinsic neoplasm. Biopsy of the lesion was recommended. RESULTS: Transventricular, endoscopic biopsy, was undertaken, with concurrent intraoperative, transendoscopic EEG recording using a standard epilepsy depth recording macroelectrode. Numerous electrographic seizures were recorded. Histopathology revealed a HH. CONCLUSION: This is the first report of intraoperative macroelectrode recording of electrographic seizures transendoscopically from a HH. This technique may prove useful for diagnosis, prognosis and treatment planning, as well as to guide transendoscopic therapeutic interventions for HH.

Cingulate epileptogenesis in hypothalamic hamartoma.

Hypothalamic hamartoma (HH) is a relatively rare cause of epilepsy, mainly affecting children. Nearly all patients develop gelastic seizures, often followed by other focal seizure types. Our case illustrates the mechanisms of epileptogenesis in HH. The patient developed gelastic attacks as a baby, and secondarily generalized seizures and drop attacks at 9 years of age. Magnetic resonance imaging (MRI) confirmed the presence of a HH. Presurgical assessment with intracranial electroencephalography (EEG) monitoring recorded gelastic seizures with generalized epileptiform activity. Functional stimulation of the hamartoma provoked gelastic attacks. Single pulse electrical stimulation (SPES) was used to identify epileptogenic cortex. SPES of the left cingular cortex provoked generalized responses similar to the spontaneous generalized discharges. Our results suggest that long-standing history of epilepsy in patients with HH may be related to additional sources of epileptogenic activity. Electrical stimulation performed in this patient provided additional data to favor the hypothesis of secondarily epileptogenesis in the cingulate gyrus independently from the primary origin in the HH.

L-Type calcium channel blockade reduces network activity in human epileptic hypothalamic hamartoma tissue.

PURPOSE: Human hypothalamic hamartomas (HHs) are associated with gelastic seizures, intrinsically epileptogenic, and notoriously refractory to medical therapy. We previously reported that the L-type calcium channel antagonist nifedipine blocks spontaneous firing and γ-aminobutyric acid (GABA)(A)-induced depolarization of single cells in HH tissue slices. In this study, we examined whether blocking L-type calcium channels attenuates emergent activity of HH neuronal networks. METHODS: A high-density multielectrode array was used to record extracellular signals from surgically resected HH tissue slices. High-frequency oscillations (HFOs, ripples and fast ripples), field potentials, and multiunit activity (MUA) were studied (1) under normal and provoked [4-aminopyridine (4-AP)] conditions; and (2) following nifedipine treatment. KEY FINDINGS: Spontaneous activity occurred during normal artificial cerebrospinal fluid (aCSF) conditions. Nifedipine reduced the total number and duration of HFOs, abolished the association of HFOs with field potentials, and increased the inter-HFO burst intervals. Notably, the number of active regions was decreased by 45 ± 9% (mean ± SEM) after nifedipine treatment. When considering electrodes that detected activity, nifedipine increased MUA in 58% of electrodes and reduced the number of field potentials in 67% of electrodes. Provocation with 4-AP increased the number of events and, as the number of electrodes that detected activity increased 248 ± 62%, promoted tissue-wide propagation of activity. During provocation with 4-AP, nifedipine effectively reduced HFOs, the association of HFOs with field potentials, field potentials, MUA, and the number of active regions, and limited propagation. SIGNIFICANCE: This is the first study to report (1) the presence of HFOs in human subcortical epileptic brain tissue in vitro; (2) the modulation of "pathologic" high-frequency oscillations (i.e., fast ripples) in human epileptic tissue by L-type calcium channel blockers; and (3) the modulation of network physiology and synchrony of emergent activity in human epileptic tissue following blockade of L-type calcium channels. Attenuation of activity in HH tissue during normal and provoked conditions supports a potential therapeutic usefulness of L-type calcium channel blockers in epileptic patients with HH.

Ictogenesis and symptomatogenesis of gelastic seizures in hypothalamic hamartomas: an ictal SPECT study.

PURPOSE: To topographically localize the ictogenic zone within hypothalamic hamartomas (HHs) and the symptomatogenic zone for gelastic seizure (GS), we analyzed data from both interictal and ictal single photon emission computed tomography (SPECT). METHODS: Ictal SPECT was performed immediately after GS onset in 21 patients with HH (aged 2-36 years, mean 13.8 years) who underwent stereotactic radiofrequency thermocoagulation (SRT). SPECT data were statistically analyzed by means of subtraction ictal SPECT coregistered to magnetic resonance imaging (MRI) (SISCOM) and statistical parametric mapping (SPM). Topographic localization of ictal hyperperfusion areas was evaluated. RESULTS: SISCOM obtained in 27 studies demonstrated ictal hyperperfusion in the HH interface zone in 16 studies of 13 patients (hot HH group). In these patients, HHs were significantly larger than those without hyperperfusion of HH in 11 studies of 8 patients (21.4 ± 10.3 vs. 12.3 ± 7.3 mm in diameter, p < 0.05, t-test). In all patients and in the hot HH group, SPM group analysis of individual differences between interictal and ictal data revealed significantly (p < 0.001) hyperperfused areas in the ipsilateral hypothalamus, mediodorsal (MD) nucleus of the thalamus and putamen, bilateral pontine tegmentum, and contralateral inferior semilunar lobule of the cerebellum. There was no hyperperfusion in the mammillothalamocingulate pathway. DISCUSSION: The present study confirmed that ictogenesis occurs in the HH interface zone, which should accordingly be the target for SRT. We suggest that a thalamopontocerebellar circuit plays an important role for stereotypical and automatic symptomatogenesis of GS and that the hypothalamus and MD nucleus of the thalamus are potentially involved in epileptic encephalopathy.

Large hypothalamic hamartoma with calcification and cystic components in an adult--case report.

A 24-year-old female presented with an unusual case of hypothalamic hamartoma manifesting as seizure. Neuroimaging findings were atypical, showing the large tumor (maximum diameter, 50 mm) with a cystic component and calcification. Surgery was performed and histological examination demonstrated heterotopia. Hamartoma should be considered in the differential diagnosis of a suprasellar, non-enhanced mass attached to the hypothalamus. Excessive unnecessary surgery should be avoided, and intraoperative pathological examination may lead to enhanced assessment and better outcomes.

Anterior interhemispheric approach for 100 tumors in and around the anterior third ventricle.

OBJECTIVE: We report our experience with anterior interhemispheric approach for tumors in and around the anterior third ventricle, including surgical technique, instrumentation, pre- and postoperative hormonal disturbances, and resection rate. METHODS: One hundred patients with 46 craniopharyngiomas, 12 hypothalamic gliomas, 12 meningiomas, 6 hypothalamic hamartomas, and 24 other lesions were operated on using an anterior interhemispheric approach with or without opening of the lamina terminalis. This surgical approach involves no frontal sinus opening; a narrow (approximately 15-20 mm in width) access between the bridging veins, which is sufficient to remove the tumor totally; and sparing of the anterior communicating artery. Specially designed long bipolar forceps and scissors are necessary for this approach, and concomitant use of angled instruments (endoscope, aspirator, and microforceps) is required frequently. The postsurgical follow-up period varied from 4 months to 18 years. RESULTS: Total removal of the neoplasm was accomplished in 37 of 46 patients with craniopharyngiomas (80.4%), whereas subtotal resection was performed in hypothalamic gliomas. No significant differences in pre- and postoperative hormonal disturbances were observed in 37 craniopharyngiomas and 10 hypothalamic gliomas. There was no operative mortality. Visual acuity was preserved or improved in 68 of 75 patients assessed. The Karnofsky Performance Scale score did not deteriorate in 72 of 75 patients tested. CONCLUSION: The minimally invasive anterior interhemispheric approach, with or without opening of the lamina terminalis, is useful for removal of tumors in and around the anterior third ventricle, such as craniopharyngiomas and hypothalamic gliomas.

[A successful surgical case of a hypothalamic hamartoma with gelastic seizure: a case report].

Gelastic seizure is a rare form of epilepsy defined as automatic bouts of laughter without mirth commonly associated with a hypothalamic hamartoma. Surgical treatment of hypothalamic hamartomas is associated with a high risk of complications because of the close vicinity of adjacent structures such as the optic tracts and mammillary bodies. This case was an 11-year-old girl who presented with gelastic seizure and complicated partial seizure. She developed gelastic seizure at a frequency of 10 bouts per day. She was found to have an elliptical mass close to the left hypothalamus. The signal intensity on magnetic resonance imaging (MRI) was consistent with hypothalamic hamartoma. The patient underwent surgical resection by a subtemporal approach. Pathological findings confirmed the diagnosis of hypothalamic hamartoma. Postoperative MRI demonstrated that the hypothalamic hamartoma was successfully resected. Twenty four months after surgery, complicated partial seizure in this patient has improved to Engel's class 1a and gelastic seizure has improved to Engel's class IIIa.