Short-term efficacy and safety of rufinamide for Lennox-Gastaut syndrome.

Objective: We examined the short-term efficacy and safety of rufinamide (RFN) in patients with Lennox-Gastaut syndrome (LGS). Methods: We performed a retrospective review of clinical records of patients with LGS who started RFN treatment between July 2013 and June 2014 at the Hokkaido Medical Center for Child Health and Rehabilitation and Midorigaoka Ryo-iku-en. Efficacy and safety were evaluated when the patients had completed three months of treatment. Patients were classified into four categories according to percent seizure reduction : remission (seizure-free), response (seizure reduction≥50%), no change (seizure reduction<50% or increase) and aggravation (seizure increase≥50%). Responder rate (RR) was the percentage of patients with≥50% decrease in seizure frequency. Results: Thirteen LGS patients (8 males, 5 females) were studied. The efficacy for tonic seizures (13 patients) was remission 1 patient, response 3 patients, no change 8 patients and aggravation 1 patient, with RR of 30.8%. Two patients discontinued LGS due to seizure aggravation. Four patients experienced transient remission. For generalized tonic clonic seizures (2 patients), 1 patient achieved remission and 1 patient showed no change. Two patients of atonic seizures showed no change. Of 2 patients of atypical absence, 1 patient showed response and 1 patient no change. Eight patients had adverse effects such as somnolence (6 patients), sleep disturbance (1 patient), and appetite loss (4 patients) including weight loss in 2 patients. There were no severe adverse effects and no discontinuation due to adverse effects. Conclusions: Short-term effectiveness for tonic seizures was observed when patients with LGS were treated with RFN, with transient remission in some patients. We consider that RFN is worth trying in patients with LGS due to its efficacy for tonic seizures and absence of severe adverse effects.

Long-term course of Dravet syndrome: a study from an epilepsy center in Japan.

OBJECTIVE: This study attempted to clarify the long-term course of Dravet syndrome (DS). METHODS: Sixty-four patients diagnosed with DS (44 with typical DS, and 20 with atypical DS) were studied. The long-term outcomes of clinical seizures, electroencephalographic findings, neuropsychological findings, and social situation were analyzed. The follow-up period ranged from 11 to 34 years 5 months (median 24 years). RESULTS: At the last visit, the ages ranged from 19 years to 45 years (median 30 years). Fifty-nine patients continued to have generalized tonic-clonic seizures (GTCS). Status epilepticus and unilateral seizures were not observed and myoclonic seizures, atypical absence seizures, and photosensitive seizures were resolved in most patients. The frequency of complex partial seizures was equally low, with five patients at presentation and six patients at the last visit, respectively. Five patients achieved seizure remission (seizure-free for 1 year or longer). Only 1 of 44 patients with typical DS had seizure remission, whereas 4 of 20 patients with atypical DS remitted, with a statistically significant difference between the two phenotypes (p = 0.03). Intellectual disability was found in all patients; especially, severe intellectual disability was prevalent. Patients with atypical DS tended to have milder intellectual disability compared to those with typical DS (p = 0.0283). Occipital alpha rhythm in the basic activity was associated with milder intellectual disability (p = 0.0085). The freedom from seizures correlated with appearance of occipital alpha rhythms (p = 0.0008) and disappearance of epileptic discharges (p = 0.0004). Two patients with GTCS died. Mutations of the neuronal voltage-gated sodium channel alpha subunit type 1 gene were detected at a high frequency (33 of 36 patients examined). Seizure remission was found only in the missense mutation group. SIGNIFICANCE: The long-term seizure and intellectual outcomes are extremely poor in patients with typical DS compared to those with atypical DS. Epilepsy phenotype may influence long-term course of DS.

Influence of CYP2C19 polymorphism and concomitant antiepileptic drugs on serum clobazam and N-desmethyl clobazam concentrations in patients with epilepsy.

OBJECTIVE: The aims of this study were to identify the factors influencing the metabolism of clobazam (CLB) and its active metabolite [N-desmethyl clobazam (NCLB)] and to evaluate the NCLB concentration as an indicator for CYP2C19 polymorphism in epileptic patients. METHODS: A total of 302 serum samples from 238 Japanese patients were evaluated. The ratios of the serum CLB and NCLB concentrations to the CLB dose (CD ratios) were calculated and compared with CYP2C19 phenotypes. RESULTS: The mean CD ratio of NCLB in extensive metabolizers (EM: *1/*1), intermediate metabolizers (IM: *1/*2 or *1/*3), and poor metabolizers (PM: *2/*2, *3/*3, or *2/*3) was 3.1, 4.9, and 21.6 (µg/mL)/(mg/kg), respectively. In the EM and IM groups, the concomitant use of hepatic enzyme inducers (phenytoin and carbamazepine) reduced the CD ratio of CLB and increased that of NCLB. In the PM group, these inducers also decreased the CD ratio for CLB but did not elevate the CD ratio for NCLB. Using multiple regression analysis, body weight showed a positive correlation with an increased CD ratio for NCLB. The concomitant use of zonisamide and stiripentol also elevated the CD ratio for NCLB in the EM and IM groups, but that of the PM group was almost unchanged. When the cut-off value of the CD ratio for NCLB was set as 10.0 (µg/mL)/(mg/kg) for predicting the CYP2C19 PM status, the sensitivity and specificity were 94.4% and 95.7%, respectively. CONCLUSIONS: The interaction between NCLB and other antiepileptic drugs showed marked differences among CYP2C19 phenotypes. Measurement of the serum NCLB concentration is clinically useful for identifying the PM phenotype.

[Efficacy of repeated adrenocorticotropic hormone therapy in patients with intractable epileptic spasms].

OBJECTIVE: We examined the effectiveness of repeated adrenocorticotropic hormone (ACTH) therapy in short-term and long-term seizure control in patients with intractable epileptic spasms. METHODS: Twenty-five patients with intractable spasms, in whom epileptic seizures were not controlled or relapsed after the first ACTH therapy, were given repeated ACTH therapy. The short-term effect (seizure control longer than two months) of repeated ACTH therapy was analyzed, and the long-term effect was estimated by Kaplan-Meier method. RESULTS: Short-term seizure control by repeated ACTH therapy was achieved in 13 of 25 patients (52.0%), and in 5 of 13 patients, seizures were controlled by ACTH therapy at higher doses compared with the first ACTH therapy. Short-term effectiveness was obtained in 76.5% of patients who had epileptic spasms alone at the time of the second ACTH therapy, but was ineffective in all 8 patients who had multiple types of seizures, with relapses within 2 months. Short-term effectiveness was not associated with clinical factors such as onset age, age of repeated ACTH treatment, and EEG findings. Regarding the long-term effect of repeated ACTH therapy, the period until seizure relapse was significantly longer in patients with epileptic spasms alone compared to patients with multiple seizure types. Spasms were controlled in 5 of 25 cases (20.0%) at the final observation. In patients with multiple seizure types and patients with onset age older than eight months, seizure control was not obtained. Long-term outcome was good in patients with treatment lag within 2 months. CONCLUSION: In repeated ACTH therapy, seizure type seems to be one of the major determinants for short- and long-term seizure outcome.

[Sleepiness:a frequent adverse reaction of antiepileptic drugs in patients with epilepsy after encephalitis/encephalopathy].

OBJECTIVE: Patients with epilepsy after encephalitis/encephalopathy (EAE) are often on polytherapy with anti-epileptic drugs (AEDs), and are at risk of adverse reactions. We examined the adverse effects of AEDs, especially sleepiness, in these patients. METHODS: In this retrospective study, the medical records of 66 patients who were diagnosed with EAE in our hospital were reviewed and the clinical characteristics were analyzed. Immunological biomarkers including cytokines, chemokines, granzyme B, soluble tumor necrosis factor receptor 1, matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 were also investigated. RESULT: The mean onset age of acute encephalitis was 9 years and 1 month and the mean interval from onset of acute encephalitis to onset of epilepsy was 6.4 months. Sleepiness induced by AEDs was observed in 26 of 66 patients (39.3%). The incidence of sleepiness was high in patients treated with clorazepate (75%), lamotrigine (66.7%), and ethosuximide (40%). Comparing the AEDs used by more than 20 patients, the incidence of sleepiness was high for clonazepam (30.4%) and phenytoin (25.8%). IgG, protein, and albumin levels in cerebrospinal fluid were significantly higher in patients affected by sleepiness than in those not affected. IL-8 in cerebrospinal fluid was significantly higher in the group with sleepiness compared to that without. Serum matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 levels were not different between the two groups. CONCLUSION: Long-lasting blood-brain barrier dysfunction and proliferation of immature vessels induced by IL-8 may contribute to the occurrence of sleepiness as an adverse effect of AEDs in patients with EAE. We recommend to assess for blood-brain barrier dysfunction when choosing AEDs for treating patients with intractable EAE.

Loss-of-function mutation of collybistin is responsible for X-linked mental retardation associated with epilepsy.

Microarray-based comparative genomic hybridization analysis identified a 737-kb microdeletion of Xq11.1, including the cell division cycle 42 guanine nucleotide exchange factor (GEF)-9 gene (ARHGEF9), encoding collybistin, which has a pivotal role in formation of postsynaptic glycine and γ-aminobutyric acid receptor clusters, in a male patient with severe mental retardation and epilepsy. No overlapping deletion with this was identified in the database of genomic copy number variations. A cohort study of ARHGEF9 nucleotide sequence identified a nonsense mutation in another male patient with severe mental retardation and epilepsy. This mutation affects one of the three transcript variants of ARHGEF9, which was confirmed to be expressed in the brain by reverse transcription-PCR. Although this nonsense mutation was shared with the patient's mother, it was not observed in 100 normal individuals. Both male patients suffered epileptic seizures after 1 year of age. Brain magnetic resonance imaging revealed mild frontal atrophy in the first patient and right frontal polymicrogyria in the second patient. Three previously reported mutations of ARHGEF9 consisted of a missense mutation in a male patient with hyperekplexia and two chromosomal disruptions in two female patients. The common phenotypic effects of all ARHGEF9 mutations were mental retardation and epilepsy. Therefore, ARHGEF9 is likely to be responsible for syndromic X-linked mental retardation associated with epilepsy.

Retrospective multiinstitutional study of the prevalence of early death in Dravet syndrome.

PURPOSE: A questionnaire survey was conducted in Japan to investigate the causes and prevalence of death related to Dravet syndrome. METHODS: A questionnaire was delivered to 246 hospitals at which physicians were treating childhood epilepsy to gain information about the total number of patients with Dravet syndrome and their prevalence of early death. KEY FINDINGS: Responses to the survey were collected from 91 hospitals, and a total of 63 of 623 patients with Dravet syndrome died. Data from 59 of these patients were analyzed. The patients' ages at death ranged from 13 months to 24 years and 11 months, with a median age of 6 years and 8 months. The analysis showed that the risk of mortality remained high up to approximately 12 years of age. The causes of mortality included sudden death in 31 patients (53%), acute encephalopathy with status epilepticus (SE) in 21 patients (36%), drowning in 6 patients (10%), and acute hepatopathy in one patient (1%). The incidence of sudden death reached a first peak at 1-3 years of age and reached a second peak at 18 years and older. In contrast, the incidence of acute encephalopathy with SE reached a sharp peak at 6 years of age. Seven of 10 patients who underwent an SCN1A mutation analysis exhibited positive mutations without a specific mutation site. SIGNIFICANCE: In the present study, the prevalence of Dravet syndrome-related mortality was 10.1%. The incidence of sudden death and acute encephalopathy with SE was the highest in infancy (1-3 years) and at early school ages (with a peak at 6 years), respectively. After approximately 12 years of age, the risk of mortality declined sharply. Neither the treatment nor the number of seizures was associated with any cause of mortality. In addition, it is difficult to predict which factors lead to a fatal outcome.

Mortality in Dravet syndrome: search for risk factors in Japanese patients.

A questionnaire survey was conducted in Japan to investigate the causes and prevalence of death related to Dravet syndrome. The questionnaire was delivered to 246 hospitals at which physicians were treating childhood epilepsy to gain information about the total number of patients with Dravet syndrome and the prevalence of early death due to the disorder. Responses to the survey were collected from 91 hospitals, and a total of 63 of 623 patients with Dravet syndrome had died. Data from 59 of these patients were analyzed. The age at death for these patients ranged from 13 months to 24 years and 11 months, with a median age of 6 years and 8 months. The causes of mortality included sudden death in 31 patients (53%), acute encephalopathy with status epilepticus (SE) in 21 patients (36%), drowning in 6 patients (10%), and other causes in one patient (1%). The incidence of sudden death reached a first peak at 1-3 years of age and a second peak at 18 years and older. In contrast, the incidence of acute encephalopathy with SE reached a peak at 6 years of age. Seven of the 10 patients who underwent SCN1A mutation analysis exhibited positive mutations but exhibited no consistent phenotype. The prevalence of Dravet syndrome-related mortality was 10.1%. The incidence of sudden death and acute encephalopathy with SE was higher in infancy (1-3 years) and at early school ages (with a peak at 6 years), respectively. Neither the treatment nor the number of seizures was associated with any cause of mortality. Factors leading to a fatal outcome are difficult to predict.

CDKL5 alterations lead to early epileptic encephalopathy in both genders.

PURPOSE: Genetic mutations of the cyclin-dependent kinase-like 5 gene (CDKL5) have been reported in patients with epileptic encephalopathy, which is characterized by intractable seizures and severe-to-profound developmental delay. We investigated the clinical relevance of CDKL5 alterations in both genders. METHODS: A total of 125 patients with epileptic encephalopathy were examined for genomic copy number aberrations, and 119 patients with no such aberrations were further examined for CDKL5 mutations. Five patients with Rett syndrome, who did not show methyl CpG-binding protein 2 gene (MECP2) mutations, were also examined for CDKL5 mutations. KEY FINDINGS: One male and three female patients showed submicroscopic deletions including CDKL5, and two male and six female patients showed CDKL5 nucleotide alterations. Development of early onset seizure was a characteristic clinical feature for the patients with CDKL5 alterations in both genders despite polymorphous seizure types, including myoclonic seizures, tonic seizures, and spasms. Severe developmental delays and mild frontal lobe atrophies revealed by brain magnetic resonance imaging (MRI) were observed in almost all patients, and there was no gender difference in phenotypic features. SIGNIFICANCE: We observed that 5% of the male patients and 14% of the female patients with epileptic encephalopathy had CDKL5 alterations. These findings indicate that alterations in CDKL5 are associated with early epileptic encephalopathy in both female and male patients.

Lamotrigine is favourable for startle-induced seizures.

Falling due to startle-induced seizures (SISs) often leads to injury. The triggers of SIS are mostly unexpected auditory stimuli, which are too common to avoid in daily life. As SISs are often refractory to conventional medications, effective therapeutic options have to be established. We report a small series of six patients treated with lamotrigine (LTG) as add-on therapy. Seizure control was improved greatly in three of the six patients, resulting in less restricted daily life, but no effect was observed in two and a skin rash developed in one. Patient 1 was a 19-year-old man. His seizure comprised of a sudden tonic extension of the extremities induced by auditory or visual stimulus. He fell down due to SISs, five to ten times a day, with frequent injuries. After adding LTG to treatment with valproate (VPA) and clobazam (CLB), SISs were reduced to once a month. Patient 2 was a 51-year-old woman. Sudden tonic extension of all limbs induced by unexpected sounds frequently threw her down onto the floor. Addition of LTG to treatment with CLB, zonisamide and phenytoin reduced her SISs from several to less than once a day. Patient 3 was a seven-year-old girl with post-encephalitic epilepsy. After adjunctive treatment of LTG to VPA, the severity of SISs became milder thus avoiding injury, although seizure frequency did not decrease. LTG is potentially effective for the treatment of SISs and may prevent falling. The addition of LTG treatment dramatically improved the lives of the patients presented here and should be considered as an option for startle-induced seizures.

[Remarkable effect of a modified ketogenic diet in a boy with focal seizures followed by epileptic spasms in a cluster].

A modified ketogenic diet was demonstrated to be remarkably effective in a child with intractable symptomatic focal epilepsy with combined seizures of focal seizures and epileptic spasms (ES) in a cluster (ESC). ES started at 8 months of age and disappeared with ACTH therapy. At the age of 13 months, the child began to have intractable focal seizures that, later, were followed by ESC 10 times a day. Brain MRI showed only a non-specific diffuse cerebral atrophy. Interictal EEG showed high amplitude diffuse disorganized slow waves with prominent sharp waves predominant over the bilateral occipital region. We started a modified ketogenic diet (mKD) treatment without fasting or a water/calorie limitation. Since the 20th day of mKD, the patient has been seizure free (6 months) without adverse effects. EEG showed remarkable improvement and he has some improvement in the developmental milestones. A modified ketogenic diet is easier to start and continue compared to the classic ketogenic diet, and should be tried in intractable epilepsies that are not treatable surgically early in life from the developmental prognosis point of view.

HPeV3-associated acute encephalitis/encephalopathy among Japanese infants.

OBJECTIVE: The current study aimed to identify and compare the clinical characteristics of human parechovirus type 3 (HPeV3)-associated acute encephalitis/encephalopathy (HPeV3E/E) between infants with abnormal brain magnetic resonance imaging (MRI) findings (typical, or MRI-positive HPeV3E/E) and those with MRI-negative findings (MRI-negative HPeV3E/E). METHODS: This is a retrospective study on patients with HPeV3 infection, and a two-step questionnaire survey performed on 837 hospitals in Japan between 2014 and 2016. RESULTS: We identified 240 infants with HPeV3 infection, of which 34 had been clinically-diagnosed HPeV3E/E (cHPeV3E/E). However, detailed clinical data were provided by 32 of the 34 patients. Among these 32, 23 had undergone MRI and were categorized into two groups, MRI-positive (n = 17) and -negative (n = 6). There were no significant intergroup differences in clinical lab results or symptoms, except for gastrointestinal symptoms that were only present in the MRI-negative patients. The MRI-positive group showed white matter involvement on brain MRI during the acute phase, and 8 patients presented with lesions on follow-up MRI. Furthermore, 4 (50%) of the 8 patients had neurological sequelae. CONCLUSION: Clinical characteristics of cHPeV3E/E patients with and without lesions on brain MRI showed no significant differences. Therefore, considering the difficulty in distinguishing febrile infants with cHPeV3E/E from those with a sepsis-like illness, during an HPeV3 infection epidemic, it is imperative to frequently perform brain MRI in febrile infants presenting with severe disease for the early diagnosis of HPeV3E/E presenting with brain lesions.

Effect of total callosotomy on KCNQ2-related intractable epilepsy.

AIM: To describe beneficial effects of callosotomy on KCNQ2-related intractable epilepsy. CASE REPORT: Our patient was a 10-year-old girl who had developed epilepsy during the neonatal period, accompanied by a suppression-burst pattern on the electroencephalography (EEG). The patient showed profound psychomotor developmental delay since early infancy. Daily seizures of versive posturing and ocular deviation were transiently controlled by carbamazepine and valproate at the age of 1 year; however, the seizures gradually increased to up to 50 times per day. Ictal EEG and positron emission tomography revealed an epileptic focus in the left frontal lobe at age 5 years. Total callosotomy resulted in marked reduction of epileptic seizures thereafter, as well as improved responses to external auditory and visual stimuli. Whole exome sequencing at age 9 identified a de novo missense variant in KCNQ2 (NM_172107.3:c.563A > C:p.(Gln188Pro)). CONCLUSION: This case supports that epilepsy surgery could benefit children with epileptic encephalopathy, even with the etiology of channelopathy.

Risk factors of cognitive impairment in pediatric epilepsy patients with focal cortical dysplasia.

OBJECTIVE: The purpose of this study was to identify the risk factors of cognitive impairment in pediatric epilepsy patients with focal cortical dysplasia (FCD). METHODS: 77 patients with histopathologically confirmed FCD were studied. The statistical relationship between cognition levels and clinical factors at presurgical evaluation was analyzed. Cognitive function was evaluated by development quotient or intelligence quotient (DQ-IQ). RESULTS: Ages at seizure onset were younger than 15 years (mean ±â€¯SD; 5.0 ±â€¯4.2 years). Mean disease duration was 14.5 ±â€¯8.5 years. Mean age at pre-surgical DQ-IQ evaluation was 34.8 ±â€¯10.7 years. Mean DQ-IQ was 60.5 ±â€¯20.5, and 41 of 77 (53.2%) patients had mental retardation (DQ-IQ < 70). Younger seizure onset and seizure clustering were significantly associated with lower DQ-IQ (p < 0.001). A multiple regression study identified higher seizure frequency pattern, a history of epileptic spasm and status epilepticus as aggravating factors of DQ-IQ decline (R2 = 0.63, p < 0.001). On the other hand, the risk was decreased in patients with habitual focal aware seizure and transient seizure-free periods up to 6 months in the course of epilepsy. FCD location (FCD site, extent of radiological lesion and laterality) and histopathology of FCD did not affect DQ-IQ. CONCLUSIONS: Our study suggests that seizure characteristics including higher seizure frequency pattern, a history of epileptic spasm, status epilepticus, seizure clustering and early onset of seizure are risk factors of cognitive impairment in FCD patients.

Quantification of BK polyoma viruria in Japanese children and adults with hemorrhagic cystitis complicating stem cell transplantation.

Polyoma BK virus (BKV) is frequently found in the urine of stem cell transplantation (SCT) patients with hemorrhagic cystitis (HC), but also occurs in SCT patients without HC. How BK viruria relates to the development of HC in SCT patients, especially in children, has not yet been fully evaluated. In the present study, we analyzed the relationship of several factors including urinary BKV load to HC development in children and adults undergoing SCT. We employed a quantitative PCR assay and evaluated 37 patients (aged 9 months-62 years) of whom 12 developed HC and 25 did not. Older age was a risk factor for the development of HC; however, other factors such as sex, primary disease, type of SCT, conditioning regimen and aGVHD were not. Peak urinary BKV values in HC patients were not higher than those in non-HC patients. Severity of HC also did not correlate with urinary BKV loads. However, in some patients who secreted higher urinary BKV loads, the peak loads were closely related with the onset of HC. Higher BKV loads may be a risk factor for the development of HC in conjunction with other coexisting factors.

Successful hemispherotomy in two refractory epilepsy patients with cerebral hemiatrophy and contralateral EEG abnormalities.

We describe two cases of refractory epilepsy with cerebral hemiatrophy and contralateral electroencephalographic (EEG) abnormalities, in which hemispherotomy of the atrophic hemisphere effectively controlled seizures. Case 1 was a 5-year-1-month-old girl with refractory bilateral asymmetrical tonic posturing seizures predominantly in the right arm. Magnetic resonance imaging showed left porencephaly corresponding to a left middle cerebral artery infarction. Case 2 was a 3-year-8-month-old boy with refractory bilateral asymmetrical tonic posturing seizures predominantly in the right arm due to atrophy of the left cerebral hemisphere after septic meningitis. Both patients had right hemiparesis and was incapable of pinching by the right hand. Contralateral interictal and ictal EEG abnormalities were observed. Interictal 99mTc-ethyl cysteinate dimer (99mTc-ECD) single photon emission computed tomography (SPECT) showed hypoperfusion and ictal 99mTc-ECD-SPECT showed hyperperfusion within the left cerebral hemisphere. Left hemispherotomy was performed. Cases 1 and 2 remained seizure-free at the last follow-up 18 months and 15 months, respectively, after surgery, and contralateral interictal EEG abnormalities disappeared. In patients with cerebral hemiatrophy and contralateral EEG abnormalities, epilepsy surgery may be considered when the laterality of seizure semiology, functional imaging findings and motor deficits were concordant with the atrophic side. Ictal SPECT is effective to confirm the epileptogenic hemisphere.

[Valproate sodium and zonisamide associated interstitial pneumonitis in an infant].

A six month-old female infant developed dyspnea when she was treated with valproate sodium (VPA) and zonisamide (ZNS) for epileptic spasms. Two weeks after its onset, her dyspnea was exacerbated by respiratory syncytial virus (RSV) infection. We diagnosed interstitial pneumonitis (IP) based on her chest CT and high serum concentrations of KL-6 and surfactant protein D. Her dyspnea improved with the treatment which included steroids, neutrophil elastase inhibitor and discontinuation of VPA and ZNS. An allergic reaction probably explains the IP in our patient because steroids were effective. Her IP might have been exacerbated by several factors including the use of two anticonvulsants (VPA, ZNS), RSV infection, and physiological low serum IgA level of infants. Drug-induced interstitial lung disease should be remembered as a possible complication of anticonvulsant treatment, such as VPA and ZNS.

Long-term safety and seizure outcome in Japanese patients with Lennox-Gastaut syndrome receiving adjunctive rufinamide therapy: An open-label study following a randomized clinical trial.

PURPOSE: To evaluate the long-term safety and seizure outcome in Japanese patients with Lennox-Gastaut syndrome (LGS) receiving adjunctive rufinamide therapy. SUBJECTS AND METHODS: We conducted an open-label extension study following a 12-week multicenter, randomized, double-blind, placebo-controlled study of adjunctive rufinamide therapy in Japanese patients with LGS. Fifty-four patients participated in the extension study. Seizure frequency was evaluated until 52 weeks after the start of the extension study. Adverse events (AEs) were evaluated throughout both studies. KEY FINDINGS: Of the 54 patients, 41 (75.9%) completed the extension study. The median duration of exposure to rufinamide was 818.0 days in all 54 patients, and 38 patients (70.4%) received rufinamide for 2 years or more. The median percent change in the frequency of tonic-atonic seizures relative to the frequency at the start of the double-blind study was -39.3% (12 weeks), -40.6% (24 weeks), -46.8% (32 weeks), -47.6% (40 weeks), and -36.1% (52 weeks). Reduction of total seizure frequency was also maintained until 52 weeks. Frequent treatment-related AEs were somnolence (20.4%), decreased appetite (16.7%), transient seizure aggravation including status epilepticus (13.0%), vomiting (11.1%), and constipation (11.1%). Adverse events were mild or moderate, except for transient seizure aggravation in three patients. Adverse events resulting in discontinuation of rufinamide were decreased appetite, drug eruption, and worsening of underlying autism. When clinically notable weight loss was defined as a decrease ≥ 7% relative to baseline, 22 patients (40.7%) experienced weight loss at least once during long-term observation, although weight loss was reported as an AE in only three patients. SIGNIFICANCE: This study demonstrated a long-term benefit of rufinamide as adjunctive therapy for Japanese patients with LGS. Exacerbation of seizures and decreased appetite/weight loss should be monitored carefully.