Utility of early single photon emission computed tomography (SPECT) in neonatal gelastic epilepsy associated with hypothalamic hamartoma

Hypothalamic hamartomas: A comprehensive review of the literature - Part 1: Neurobiological features, clinical presentations and advancements in diagnostic tools

Hypothalamic hamartomas (HH) are rare, non-neoplastic heterotopic tissues which contains normal neurons and glia including oligodendrocytes and fibrillary astrocytes but in an abnormal distribution. They arise from the floor of the third ventricle, tuber cinereum, or mammillary bodies. Estimated incidence ranges from 1 in 50,000-1 in 1,000,000. Hypothalamic hamartomas are associated with different clinical presentations including various types of seizures, most characteristically; the gelastic seizures, precocious puberty, cognitive impairment, and behavioral changes. In this review, the authors discuss advancements in different diagnostic elements of hypothalamic hamartoma; including clinical features, EEG findings, and neuroimaging techniques. Moreover, different classifications described in the literature will be discussed.

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.

Mechanisms of intrinsic epileptogenesis in human gelastic seizures with hypothalamic hamartoma

Human hypothalamic hamartoma (HH) is a rare developmental malformation often characterized by gelastic seizures, which are refractory to medical therapy. Ictal EEG recordings from the HH have demonstrated that the epileptic source of gelastic seizures lies within the HH lesion itself. Recent advances in surgical techniques targeting HH have led to dramatic improvements in seizure control, which further supports the hypothesis that gelastic seizures originate within the HH. However, the basic cellular and molecular mechanisms of epileptogenesis in this subcortical lesion are poorly understood. Since 2003, Barrow Neurological Institute has maintained a multidisciplinary clinical program to evaluate and treat patients with HH. This program has provided a unique opportunity to investigate the basic mechanisms of epileptogenesis using surgically resected HH tissue. The first report on the electrophysiological properties of HH neurons was published in 2005. Since then, ongoing research has provided additional insights into the mechanisms by which HH generate seizure activity. In this review, we summarize this progress and propose a cellular model that suggests that GABA-mediated excitation contributes to epileptogenesis in HH lesions.

Hypothalamic hamartomas. Part 1. Clinical, neuroimaging, and neurophysiological characteristics

Hypothalamic hamartomas are uncommon but well-recognized developmental malformations that are classically associated with gelastic seizures and other refractory seizure types. The clinical course is often progressive and, in addition to the catastrophic epileptic syndrome, patients commonly exhibit debilitating cognitive, behavioral, and psychiatric disturbances. Over the past decade, investigators have gained considerable knowledge into the pathobiological and neurophysiological properties of these rare lesions. In this review, the authors examine the causes and molecular biology of hypothalamic hamartomas as well as the principal clinical features, neuroimaging findings, and electrophysiological characteristics. The diverse surgical modalities and strategies used to manage these difficult lesions are outlined in the second article of this 2-part review.

Dynamic Causal Modelling of epileptic seizure propagation pathways: a combined EEG-fMRI study

Simultaneous EEG-fMRI offers the possibility of non-invasively studying the spatiotemporal dynamics of epileptic activity propagation from the focus towards an extended brain network, through the identification of the haemodynamic correlates of ictal electrical discharges. In epilepsy associated with hypothalamic hamartomas (HH), seizures are known to originate in the HH but different propagation pathways have been proposed. Here, Dynamic Causal Modelling (DCM) was employed to estimate the seizure propagation pathway from fMRI data recorded in a HH patient, by testing a set of clinically plausible network connectivity models of discharge propagation. The model consistent with early propagation from the HH to the temporal-occipital lobe followed by the frontal lobe was selected as the most likely model to explain the data. Our results demonstrate the applicability of DCM to investigate patient-specific effective connectivity in epileptic networks identified with EEG-fMRI. In this way, it is possible to study the propagation pathway of seizure activity, which has potentially great impact in the decision of the surgical approach for epilepsy treatment.

The gelastic seizures-hypothalamic hamartoma syndrome: facts, hypotheses, and perspectives

Hypothalamic hamartoma (HH) can be associated with a wide spectrum of epileptic conditions, ranging from a mild form with seizures characterized by urge to laugh and no cognitive involvement up to a catastrophic encephalopathy with early onset gelastic seizures (GS), precocious puberty, and mental retardation. Moreover, a refractory, either focal or generalized, epilepsy develops during the clinical course in nearly all the cases. Neurophysiologic and neuroimaging studies have demonstrated that HH itself generates GS and starts a process of secondary epileptogenesis responsible for refractory focal or generalized epilepsy. The intrinsic epileptogenicity of HH may be explained by the neurophysiological properties of small GABAergic, spontaneously firing HH neurons. Surgical ablation of HH can reverse epilepsy and encephalopathy. Gamma-knife radiosurgery and image-guided robotic radiosurgery seem to be useful and safe approaches for treatment, in particular of small HH. Here, we review this topic, based on literature reports and our personal observations. In addition, we discuss pathogenetic hypotheses and suggest new approaches to this intriguing issue.

Long-term outcome after emergency resection of hypothalamic hamartomas for status gelasticus

OBJECT

Gelastic seizures are epileptic events characterized by bouts of laughter. They are rare and mostly associated with hypothalamic hamartomas (HHs). Status gelasticus, a rare form of status epilepticus, is defined as a prolonged cluster of gelastic seizures (> 20-30 minutes) without necessarily involving loss of awareness between seizures. Emergency resection of the hamartoma is highly effective in these situations and should be considered as early as possible. The authors retrospectively reviewed their surgical cases to document the success, complications, and long-term follow-up after emergency resection of HHs for status gelasticus.

METHODS

The authors report on a retrospective case series from a single tertiary care center. Three patients who presented with status gelasticus underwent emergency resection of HHs. Demographic details, seizure history, medical treatment, and postoperative follow-up data were evaluated. Long-term follow-up (minimum 2 years) data were obtained either from the last clinic visit notes or via telephone and e-mail contacts. The institutional review board at St. Joseph's Hospital approved this study.

RESULTS

In the last 7 years, of 157 patients who underwent HH resection, the resection was performed on an emergency basis for status gelasticus in 3 cases. At emergency surgery, these 3 patients ranged in age from 9 months to 3.5 years. All of the patients were boys. Delalande and Fohlen Type II, III, and IV lesions were present in the 3 patients. Surgical approaches for resection of HH included an orbitozygomatic, transcallosal anterior interforniceal approach and endoscopic resection. Status gelasticus was terminated following emergency surgery in all cases, and 1 patient was seizure free. Postsurgical complications included, in 1 case, a small right thalamic infarct with mild transient left hemiparesis, which completely resolved within 2 days. Within 2 years of their original surgery, 2 patients underwent further elective surgeries (endoscopic resection and radiosurgery for persistent symptomatic seizures). Follow-up since their most recent surgery ranged from 8 months to 2 years. Two patients were seizure free and 1 patient had greater than 50% reduction in seizures.

CONCLUSIONS

Status gelasticus associated with HHs can be successfully terminated by emergency resection of the HH. Long-term follow-up in the present series suggests good seizure freedom results or at least greater than 50% reduction in seizures, although repeat operations were necessary.

Role of single photon emission computed tomography in epilepsy

Molecular imaging with ictal single photon emission computed tomography (SPECT) is an established functional imaging modality for the presurgical evaluation of patients with refractory partial onset seizures. SPECT coregistered on to the MRI has greater sensitivity to identify the ictal onset zone. Ictal SPECT should always be interpreted in the context of other presurgical investigations. Ictal SPECT is sensitive method for the lateralization of TLE, but ictal SPECT is more sensitive when MRI is normal. Ictal SPECT and interictal PET are complementary to each other in lateralizing the side in patients with TLE and normal MRI. In extratemporal epilepsy, ictal SPECT will guide the placement of surface grid and depth electrodes.

A review on the management of epilepsy associated with hypothalamic hamartomas

INTRODUCTION

Hypothalamic hamartomas are rare congenital malformations located in the region of the tuber cinereum and third ventricle. Patients may be asymptomatic, but the usual presentation is gelastic seizures, precocious puberty, and/or developmental delay.

CLINICAL PRESENTATION

Without surgical intervention, the gelastic seizures, which are typically present in childhood, may progress to other seizure types, including generalized epilepsy, and are generally refractory to antiepileptic drugs.

SUMMARY

This review will discuss the clinical and electrophysiologic aspects of these lesions, as well as treatment options, including surgery, endoscopy, and radiosurgery.

Gelastic seizures associated with hypothalamic hamartomas. An update in the clinical presentation, diagnosis and treatment

Gelastic seizures are epileptic events characterized by bouts of laughter. Laughter-like vocalization is usually combined with facial contraction in the form of a smile. Autonomic features such as flushing, tachycardia, and altered respiration are widely recognized. Conscious state may not be impaired, although this is often difficult to asses particularly in young children. Gelastic seizures have been associated classically to hypothalamic hamartomas, although different extrahypothalamic localizations have been described. Hypothalamic hamartomas are rare congenital lesions presenting with the classic triad of gelastic epilepsy, precocious puberty and developmental delay. The clinical course of patients with gelastic seizures associated with hypothalamic hamartomas is progressive, commencing with gelastic seizures in infancy, deteriorating into more complex seizure disorder resulting in intractable epilepsy. Electrophysiological, radiological, and pathophysiological studies have confirmed the intrinsic epileptogenicity of the hypothalamic hamartoma. Currently the most effective surgical approach is the trancallosal anterior interforniceal approach, however newer approaches including the endoscopic and other treatment such as radiosurgery and gamma knife have been used with success. This review focuses on the syndrome of gelastic seizures associated with hypothalamic hamartomas, but it also reviews other concepts such as status gelasticus and some aspects of gelastic seizures in other locations.

Radiosurgery for hypothalamic hamartomas

Radiosurgery plays an important role in the treatment of refractory seizures induced by hypothalamic hamartomas (HHs). These lesions, deeply located and surrounded by a delicate vascular and neuronal network, are often associated with catastrophic epilepsy leading to progressive cognitive and behavioral deterioration. Surgical approaches include microsurgical resection, endoscopic resection or disconnection, radiofrequency lesioning, and interstitial brachytherapy. Radiosurgery is an emerging treatment modality for HHs, which provides excellent seizure outcomes and no lasting complications to date.

Intractable gelastic seizures during infancy: ictal positron emission tomography (PET) demonstrating epileptiform activity within the hypothalamic hamartoma

Gelastic seizures comprise a very rare form of epilepsy. They present with recurrent bursts of laughter voices without mirth and are most commonly associated with the evolution of a hypothalamic hamartoma. The purpose of this article is to describe the second reported ictal fluorodeoxyglucose-positron emission tomography study in a unique case of an infant with intractable gelastic seizures since the neonatal period associated with a hypothalamic hamartoma. The patient presented at 4 months old with recurrent, almost persistent, gelastic seizures consisting of laughter bouts without mirth. The seizures were noticeable at the first week of life and increased in frequency to last up to 12 hours, namely status gelasticus. These gelastic fits were accompanied with focal motor seizures, including unilateral right-eye blinking and mouth twitching. Developmental mile-stones were intact for age. Magnetic resonance imaging of the cortex demonstrated a large hypothalamic hamartoma within the third ventricle, hampering cerebrovascular fluid drainage of the lateral ventricles. An electroencephalography was nondiagnostic. Ictal fluorodeoxyglucose-positron emission tomography demonstrated a large circumscribed hypermetabolic region within the location of the hypothalamic hamartoma, representing localized intense epileptiform activity. The infant became instantly free of all seizure types given minute doses of oral benzodiazepine (clonazepam) and remains completely controlled after 12 months. Her overall development remains intact. This ictal fluorodeoxyglucose-positron emission tomography is the second reported study verifying that the main source of the epileptic activity inducing gelastic seizures originates from the hypothalamic hamartoma itself; therefore, a complementary fluorodeoxyglucose-positron emission tomography study should be considered in any patient presenting with intractable gelastic seizures, especially in those associated with hypothalamic hamartoma, in order to localize the region of epileptiform activity amenable to surgical resection if intensive drug therapy fails.

Pediatric-onset gelastic seizures: clinical data and outcome

Gelastic seizures are an extremely rare form of epilepsy defined as automatic bouts of laughter without mirth commonly associated with a hypothalamic hamartoma. The objective was to survey all Israeli children found to develop recurrent gelastic seizures and report presenting symptoms, electroencephalographic and radiologic data, and response to either antiepileptic drugs or surgery. Ten children who developed gelastic seizures at the age of 1 week to 6.5 years (mean, 25 months) at a frequency from 3 bouts per week to >10 prolonged bouts per day were followed for a period of 1.3-12 years (mean, 6 years). Seven cases were defined as symptomatic: cortical magnetic resonance imaging revealed a hypothalamic hamartoma in four patients and cortical abnormalities in three others. Seizure control was achieved in four patients, including a neonate with status gelasticus and hypothalamic hamartoma, and partial control in one more. Five children remained resistant to polytherapy, including three with hypothalamic hamartoma even after two of them underwent hemartoma excision. Thus, children with gelastic seizures may respond relatively well to drug therapy. Four of the 10 patients became seizure free with drug therapy; in three intractable symptomatic cases, surgery was tried but failed in two of the three.

Epilepsy in hypothalamic hamartoma: clinical and EEG features

Hypothalamic hamartoma (HH) is a congenital malformation of the hypothalamus that may be asymptomatic or manifest with precocious puberty or seizures. Gelastic seizures often begin early in life, even in the newborn period, being manifest by frequent attacks of inappropriate laughter resulting from seizure activity in the HH. The scalp electroencephalogram (EEG) is often normal in children with gelastic seizures, such that the diagnosis of epilepsy and the finding of a HH are often delayed. In a proportion of children with HH, there is an epileptic progression, in which complex partial seizures with frontal, temporal, and lateralized clinical features appear, usually with the appearance of focal slowing and epileptiform activity on the interictal EEG. Further progression may ensue with the appearance of tonic or atonic drop attacks, generalized tonic-clonic seizures, and epileptic spasms; rarely, infantile spasms may be the presenting seizure type. With the appearance of generalized seizures, the interictal EEG shows bilaterally synchronous and generalized epileptiform activity, often in abundance. The mechanism of this evolution is incompletely understood but neocortical seizure propagation and secondary epileptogenesis are believed to be important. Paralleling the development of the focal and generalized electroclinical manifestations in children with HH is usually slowing of development and the appearance of behavioral problems. Fortunately, many of these neurologic manifestations can be arrested, or reversed, with effective surgical treatment directed at the HH.

Hypothalamic hamartomas--clinical, neuropathological and surgical aspects

INTRODUCTION

Hypothalamic hamartomas are rare congenital lesions of the tuber cinereum presenting with the classic triad of gelastic epilepsy, central precocious puberty and developmental delay. The clinical course in the majority is one of progression, commencing with gelastic seizures in infancy, deteriorating into more complex seizure disorders and resulting in a catastrophic epilepsy associated with a concomitant cognitive and behavioural decline.

OBSERVATION

Electrophysiological, radiological and pathophysiological studies have confirmed the intrinsic epileptogenicity of the hypothalamic hamartoma. Secondary generalised epilepsy seen in this condition is theorised to be through propagation via the mamillothalamic pathways with attachment to the mamillary bodies identified on MRI. Indications as to timing for surgery remain ill-defined although there is a theoretical argument to intervene before the development of secondary generalised epilepsy.

SURGICAL APPROACH

Currently, the most effective surgical route appears to be the transcallosal anterior interforniceal approach although newer approaches of endoscopic disconnection and radiosurgery are being assessed.

Epilepsy related to hypothalamic hamartomas: surgical management with special reference to gamma knife surgery

OBJECTIVE

A large spectrum of surgical techniques can be proposed to young patients presenting with hypothalamic hamartomas (HH) associated with severe epilepsy. The aim of this report is to point on some clinical and anatomical parameters supposed to influence the choice of the surgical approach and to emphasize the specific role of radiosurgery.

MATERIALS AND METHODS

We reviewed both our experience and the recent literature based on a Pubmed search. Lateral pterional, midline frontal through the lamina terminalis, transcallosal interforniceal approaches, endoscopic treatment through the foramen of Monro, disconnecting surgery, radiofrequency ablation, brachytherapy and gamma knife surgery (GKS) were all considered. Mortality, morbidity, and efficacy of each of these techniques were compared. Specific limits, difficulties, and constraints were taken into account. Our experience of radiosurgery is based on a prospective trial which enrolled 60 patients with HH and associated severe epilepsy between October 1999 and December 2005.

RESULTS

Several surgical techniques can lead to a real reversal of the epileptic encephalopathy. The main factors for the decision-making process are the age, the size of the lesion and its anatomical type (according to our original classification), the severity of the epilepsy, and the severity of the cognitive/psychiatric comorbidity. In our prospective trial (GKS), 27 patients have a follow-up superior to 3 years. Among those, 59.2% have an excellent result with a dramatic behavioral and cognitive improvement and are completely seizure-free (37%) or have only rare non-disabling seizures (22.2%). No permanent neurological complication has been observed so far; three patients have presented a transient poïkilothermia. GKS is clearly the safer approach for these difficult patients. Young patients with severe epilepsy and comorbidity must be operated on using a curative approach as early as possible. Very large type VI or mixed type with a large component above the floor of the third ventricle must be disconnected and then the upper remnant can be ideally treated by GKS (staged surgery). Type V (rarely epileptic) and IV are frequently operable by disconnection. Type I HH deeply embedded in the hypothalamus are operated on by GKS efficiently and safely. Type II HH can be operated on either endoscopically or transcallosally or by GKS depending on the parents' choice and severity of epilepsy. In small type III HH, GKS is a safer procedure, due to the very close relationship to the fornix and mammillary bodies. In very large type III HH, transcallosal interforniceal approach is proposed but with significant risks especially concerning short-term memory. When the lesion is sufficiently small, GKS is globally offering the patient a rate of seizure cessation comparable to microsurgery with, however, a much lower risk (no neurological deficit reported till now).

CONCLUSION

Our first results indicate that GKS is as effective as microsurgical resection and very much safer. GKS also allows avoiding the vascular risk related to radiofrequency lesioning or stimulation. The disadvantage of radiosurgery is its delayed action. Longer follow-up is mandatory for a reliable evaluation of the role of GKS. The early effect on subclinical discharges turns out to play a major role in the dramatic improvement of sleep quality, behavior, and developmental learning acceleration at school.

Hypothalamic hamartoma with gelastic seizures in Swedish children and adolescents

BACKGROUND

Hypothalamic hamartoma with gelastic seizures (HHGS) is an uncommon, often unrecognized, epileptic syndrome with onset of symptoms during childhood.

AIM

In order to study the occurrence, clinical symptoms and different investigations of HHGS in Swedish children and adolescents, a nationwide survey was undertaken. Methods. Twelve patients, three females, aged 5 to 19 years were identified and their hospital records reviewed. MRI examinations were reinvestigated.

RESULTS

Gelastic seizures were noted before the age of six months in seven patients in at least three as early as the neonatal period. During the course of disease one or more other seizure types developed in 11 patients. Behaviour disorder became subsequently obvious in ten patients, and mental retardation was diagnosed in seven. Precocious puberty was diagnosed in five patients. A total of 46 MRI examinations were performed in 11 patients, revealing hypothalamic tumors, eight of which were drooping with a broad base. Interictal and ictal EEG examinations were pathological in 10 patients with nonspecific results. Nonspecific results were also found on SPECT and PET performed in six and two patients, respectively. Available antiepileptic drugs had little or no effect on gelastic seizures, but some effect on other seizure types. Precocious puberty was treated with a GnRH-agonist. Neurosurgical treatment of the hypothalamic hamartoma, performed in three patients, had a rather good outcome concerning gelastic seizures and behaviour. Vagal nerve stimulation in five patients had no effect.

CONCLUSIONS

Review of the literature and experience from this group's own cases confirms that early diagnosis of HHGS is important. Hypothalamic hamartoma should be considered in any child with laughing attacks. MRI investigation is compulsory, and neurosurgery the most important treatment.

Hypothalamic hamartomas: seven cases and review of the literature

Hypothalamic hamartomas constitute rare developmental lesions associated with gelastic epilepsy and/or precocious puberty (PP). We elected to review cases encountered at our center (7 patients) and the existing literature (277 patients) to obtain a better understanding of the clinical aspects, pathogenesis, and treatment of this entity. Evidence suggests that gelastic seizures are due to intrinsic epileptogenicity. The cause of the subsequent development of other seizure types, cognitive decline, and diffuse spike-and-wave pattern remains unresolved and is addressed. Anticonvulsants often fail to control seizures and different surgical options are available. Available evidence suggests that a resection through a subtemporal approach is best for lesions that are pedunculated or with a significant prepontine component, while a transcallosal approach is more appropriate for sessile lesions with an intraventricular component. Gamma knife surgery may be especially useful for small sessile lesions, failed partial resections, or patients not appropriate or refusing open surgery.

The role of subcortical structures in human epilepsy

Like normal cerebral function, epileptic seizures involve widespread network interactions between cortical and subcortical structures. Although the cortex is often emphasized as the site of seizure origin, accumulating evidence points to a crucial role for subcortical structures in behavioral manifestations, propagation, and, in some cases, initiation of epileptic seizures. Extensive previous studies have shown the importance of subcortical structures in animal seizure models, but corresponding human studies have been relatively few. We review the existing evidence supporting the importance of the thalamus, basal ganglia, hypothalamus, cerebellum, and brain stem in human epilepsy. We also propose a "network inhibition hypothesis" through which focal cortical seizures disrupt function in subcortical structures (such as the medial diencephalon and pontomesencephalic reticular formation), leading secondarily to widespread inhibition of nonseizing cortical regions, which may in turn be responsible for behavioral manifestations such as loss of consciousness during complex partial seizures.

Gelastic seizure with hypothalamic hamartoma: proton magnetic resonance spectrometry and ictal electroencephalographic findings in a 4-year-old girl

Gelastic seizure is a rare symptom often associated with hypothalamic hamartoma. We present here a 4-year-old girl with gelastic epilepsy caused by hypothalamic hamartoma and report the magnetic resonance spectrometry and electroencephalographic (EEG) findings. At the age of 2 1/2 years, she developed brief, repetitive laughing attacks or mixed attacks with laughing and crying, which were refractory to carbamazepine. An interictal EEG showed intermittent slow waves in the left frontocentral region and sporadic positive sharp waves in the left centroparietal area. Ictal EEG demonstrated dysrhythmic theta activity in the left central area 3 seconds after the onset of laughing. Brain magnetic resonance imaging demonstrated a large sessile mass, isointense to gray matter, in the region of the hypothalamus, suggesting hypothalamic hamartoma. Proton magnetic resonance spectrometry of the hypothalamic hamartoma revealed a significant reduction of the N-acetylaspartate/serum creatinine ratio. The altered chemical shift imaging with magnetic resonance spectrometry in our patient suggests a biochemical abnormality in the tissue of the hypothalamic hamartoma. Moreover, this abnormal function of the hamartoma tissue might be closely related to epileptogenesis because the time difference between the ictal laughter and the subsequent EEG changes in the ictal EEG does not support the idea that the activated cortex is the epileptogenic focus.