Faculty Bibliography

OBJECTIVE:New-onset refractory status epilepticus (NORSE) occurs in people without pre-existing epilepsy or a rapidly identified structural, toxic, metabolic, or other cause. NORSE is a rare disorder with high morbidity and mortality rates and limited evidence for effective therapies. We aimed to assess whether the gut microbiome of NORSE and status epilepticus (SE) differs from that of chronic epilepsy, whether NORSE differs from SE at different disease time points, and to examine the correlations between specific gut microbiota and cytokines in NORSE and SE. METHODS:This longitudinal cohort study observed patients with NORSE (n = 15), SE (n = 17), and chronic epilepsy who were not in SE (n = 12). NORSE patients were recruited through the NORSE Consortium. Patients with NORSE and SE underwent longitudinal serial biospecimen collection. Fecal samples were subjected to whole-community shotgun metagenomics to characterize microbiome features. Cohorts were evaluated for prokaryotic, eukaryotic, and functional diversity. Correlations between blood inflammatory cytokine levels and microbiome features and covariate analysis with critical illness and clinical treatments were examined for NORSE and SE patients during and after SE resolution. RESULTS:During SE, NORSE and SE patients had significantly different prokaryotic, eukaryotic, and functional microbiome levels compared to chronic epilepsy patients without SE. Limited microbiome differences were observed within and between NORSE and SE, although these groups displayed differing correlation patterns between microbial species and cytokines. Patients who later died or were tube-fed harbored significantly different microbiomes than those who survived or were orally fed. SIGNIFICANCE/CONCLUSIONS:NORSE and SE patients present with a more variable and dramatically different fecal microbiome than chronic epilepsy patients, which may indicate gut dysbiosis that may be reciprocally linked to inflammatory responses. Although NORSE and SE patients had similar microbiome structures, fungal and bacterial correlates with inflammatory cytokines differed between NORSE and SE, with confounding factors influencing microbiome structure. Our data suggest a microbiome-specific response to NORSE and SE, with implications for future treatment strategies.

OBJECTIVE:In traditionally designed randomized clinical trials of antiseizure medications, participants take a blinded treatment for a prespecified number of weeks, irrespective of continued seizures. The alternative design time to prerandomization monthly seizure count (T-PSC) allows participants to end the blinded treatment after an individually prespecified number of seizures, which shortens exposure to placebo and ineffective treatment. Previous reanalyses have shown that T-PSC replicated the efficacy conclusions of trials; therefore, we evaluated whether T-PSC also could replicate tolerability and safety conclusions. METHODS:We retrospectively applied the T-PSC design to analyze treatment-emergent adverse events (TEAEs) from three blinded, placebo-controlled trials of perampanel for focal onset seizures (NCT00699972, NCT00699582, NCT00700310). We evaluated the incidences of TEAEs, treatment-related TEAEs, serious TEAEs, and TEAEs that prompted medication adjustment compared to those observed during the full-length trial. RESULTS:Of the 1480 participants in the three trials, 1093 experienced any TEAE, of whom 1006 (92%) had onset prior to T-PSC. When evaluating the differences in each type of TEAE for each dose of perampanel from placebo within each trial, there was no consistent pattern of under- or overestimation. Across the three studies, 23 of 79 (29%) serious TEAEs, most requiring hospitalization, occurred after T-PSC. SIGNIFICANCE/CONCLUSIONS:Almost all TEAEs occurred before T-PSC. Similar conclusions regarding the tolerability and safety of perampanel would have been reached if the T-PSC design had been used. This suggests that the T-PSC design may potentially benefit participants by allowing earlier change from an ineffective treatment to an alternate treatment, which could reduce the risk of serious consequences of ineffective treatment, such as hospitalization.

Tractography is a unique modality for the in vivo measurement of structural connectivity, crucial for understanding brain networks and neurological conditions. With increasing b-value, the diffusion-weighting signal becomes primarily sensitive to the intra-axonal signal. However, it remains unclear how tractography is affected by this observation. Here, using open-source datasets, we showed that at high b-values, DWI reduces the uncertainty in estimating fiber orientations. Specifically, we found the ratio of biologically-meaningful longer-range connections increases, accompanied with downstream impact of redistribution of connectome and network metrics. However, when going beyond b = 6000 s/mm², the loss of SNR imposed a penalty. Lastly, we showed that the data reaches satisfactory reproducibility with b-values above 1200 s/mm². Overall, the results suggest that using b-values above 2500 s/mm² is essential for more accurate connectome reconstruction by reducing uncertainty in fiber orientation estimation, supporting the use of higher b-value protocols in standard diffusion MRI scans and pipelines.

The ability to connect the form and meaning of a concept, known as word retrieval, is fundamental to human communication. While various input modalities could lead to identical word retrieval, the exact neural dynamics supporting this process relevant to daily auditory discourse remain poorly understood. Here, we recorded neurosurgical electrocorticography (ECoG) data from 48 patients and dissociated two key language networks that highly overlap in time and space, critical for word retrieval. Using unsupervised temporal clustering techniques, we found a semantic processing network located in the middle and inferior frontal gyri. This network was distinct from an articulatory planning network in the inferior frontal and precentral gyri, which was invariant to input modalities. Functionally, we confirmed that the semantic processing network encodes word surprisal during sentence perception. These findings elucidate neurophysiological mechanisms underlying the processing of semantic auditory inputs ranging from passive language comprehension to conversational speech.

Autoimmune encephalitis (AE), defined by clinical criteria and its frequent association with neural autoantibodies, often manifests with seizures, which usually stop with immunotherapy. However, a subset of encephalitic conditions present with recurrent seizures that are resistant to immunotherapy. Three primary neurological constellations that fall within this subset are discussed in this Perspective: temporal lobe epilepsy with antibodies against glutamic acid decarboxylase, epilepsy in the context of high-risk paraneoplastic antibodies, and epilepsy following adequately treated surface antibody-mediated AE. These entities all share a common mechanism of structural injury and potentially epileptogenic focal neural loss, often induced by cytotoxic T cells. Recently, we have proposed conceptualizing these conditions under the term autoimmune encephalitis-associated epilepsy (AEAE). Here, we discuss the new concept of AEAE as an emerging field of study. We consider the clinical characteristics of patients who should be investigated for AEAE and highlight the need for judicious use of traditional epilepsy therapeutics alongside immunotherapeutic considerations that are of uncertain and incomplete efficacy for this group of disorders. Last, we discuss future efforts needed to diagnose individuals before structural epileptogenesis has superseded inflammation and to develop improved therapeutics that target the specific immunological or functional disturbances in this entity.

OBJECTIVE:This study was undertaken to investigate diagnostic delay in adolescent onset focal epilepsy, including reasons for longer delays and associated morbidities. METHODS:Secondary analysis was done using enrollment data from the Human Epilepsy Project, a multi-institutional cohort including 34 sites in the USA, Canada, Finland, Austria, and Australia (2012-2017). Participants were aged 11-64 years at enrollment and within 4 months of treatment initiation for newly diagnosed focal epilepsy. Participants with seizure onset at age ≤ 21 years were evaluated. Data included seizure diaries documenting onset, frequency, and characteristics of seizures, reasons for diagnostic delays, and prediagnosis morbidities, including injuries, suicidal ideation, and self-injurious behaviors. RESULTS: = 7.04, p = .008). SIGNIFICANCE/CONCLUSIONS:This study highlights significant delays in diagnosing adolescent onset focal epilepsy, especially in cases with nonmotor seizures. These delays, often due to lack of recognition by patients and health care providers, are linked to more frequent seizures, higher injury rates, and increased suicidal ideation and self-injury. Early recognition and diagnosis may mitigate adverse outcomes and improve quality of life for adolescents with epilepsy.

The International League Against Epilepsy (ILAE) has updated the operational classification of epileptic seizures, building upon the framework established in 2017. This revision, informed by the implementation experience, involved a working group appointed by the ILAE Executive Committee. Comprising 37 members from all ILAE regions, the group utilized a modified Delphi process, requiring a consensus threshold of more than two thirds for any proposal. Following public comments, the Executive Committee appointed seven additional experts to the revision task force to address and incorporate the issues raised, as appropriate. The updated classification maintains four main seizure classes: Focal, Generalized, Unknown (whether focal or generalized), and Unclassified. Taxonomic rules distinguish classifiers, which are considered to reflect biological classes and directly impact clinical management, from descriptors, which indicate other important seizure characteristics. Focal seizures and those of unknown origin are further classified by the patient's state of consciousness (impaired or preserved) during the seizure, defined operationally through clinical assessment of awareness and responsiveness. If the state of consciousness is undetermined, the seizure is classified under the parent term, that is, the main seizure class (focal seizure or seizure of unknown origin). Generalized seizures are grouped into absence seizures, generalized tonic-clonic seizures, and other generalized seizures, now including recognition of negative myoclonus as a seizure type. Seizures are described in the basic version as with or without observable manifestations, whereas an expanded version utilizes the chronological sequence of seizure semiology. This updated classification comprises four main classes and 21 seizure types. Special emphasis was placed on ensuring translatability into languages beyond English. Its aim is to establish a common language for all health care professionals involved in epilepsy care, from resource-limited areas to highly specialized centers, and to provide accessible terms for patients and caregivers.

OBJECTIVE/UNASSIGNED:The authors aimed to characterize the long-term psychiatric outcomes and their predictors among survivors of autoimmune encephalitis (AE). METHODS/UNASSIGNED:In this retrospective cohort study, patients diagnosed as having AE between 2008 and 2023 at two academic medical centers (in New York City and Toronto) completed the Mini International Neuropsychiatric Interview 7.0.2 (MINI) and Profile of Mood States (POMS-2) to assess long-term psychiatric outcomes. Clinical characteristics were assessed for potential predictors of psychiatric outcomes. Bivariate analyses and univariate logistic regressions were conducted to assess the relationship between the predictors and the primary outcome. RESULTS/UNASSIGNED:-methyl-d-aspartate (33%), anti-leucine-rich-glioma-inactivated 1 (24%), anti-glutamic acid decarboxylase 65 (14%), and antibody-negative encephalitis (29%). In total, 71% of participants who completed the MINI met criteria for a DSM-5 diagnosis, and 56% were diagnosed as having a mood disorder. Thirteen participants (31%) reported above-average total mood disturbance on the POMS-2. Mann-Whitney U tests revealed that participants diagnosed as having a mood disorder self-reported significantly higher levels of confusion and bewilderment (z=-2.04, p=0.04) and depression and dejection (z=-2.24, p=0.03) and lower levels of vigor and activity (z=-2.62, p=0.01). CONCLUSIONS/UNASSIGNED:AE survivors have a high prevalence of psychiatric comorbid conditions, with most being diagnosed as having a mood disorder and a significant proportion endorsing ongoing mood disturbance. Patients with a psychiatric history may benefit from closer psychiatric follow-up.

INTRODUCTION/UNASSIGNED:Seizures are common in autoimmune encephalitis (AE), but identifying patients at risk of chronic epilepsy in the post-acute phase remains challenging. This study aims to identify risk factors of treatment-resistant postencephalitic epilepsy. METHODS/UNASSIGNED:This retrospective cohort study included patients with AE who experienced new-onset seizures within one year of symptom onset from two tertiary care centers in New York. EEG findings were analyzed separately based on whether the EEG recording was obtained in the acute (<3 months from symptom onset) or subacute phase. A multivariate logistic regression model was used to identify independent predictors of postencephalitic epilepsy. RESULTS/UNASSIGNED:Eighty-nine patients were included (median age: 33 years). Neural antibodies were present in 73% of patients (NMDAR: 35, LGI1: 19, GAD65: 9, Hu: 1, AGNA-1: 1). Over a median follow-up of 4.9 years, 29.2% developed treatment-resistant postencephalitic epilepsy. Independent predictors of postencephalitic epilepsy included focal slowing on acute EEG (OR 0.15, CI 0.02-0.90), interictal epileptiform discharges (IEDs) or periodic discharges (PDs) on subacute EEG (OR 20.01, CI 1.94-206.44), and cell surface antibodies (OR 0.21, CI 0.05-0.89). Immunotherapy within three months of onset was associated with decreased epilepsy development in patients with neural antibodies (OR 4.16, CI 1.11-16.30). CONCLUSIONS/UNASSIGNED:Nearly one-third of patients with AE and acute seizures developed treatment-resistant postencephalitic epilepsy, with significant predictors including absence of focal slowing on acute EEG, presence of IEDs and PDs on subacute EEG, absence of cell surface antibodies, and absence of early immunotherapy treatment of patients with positive neural antibodies.

OBJECTIVE:To report interim data from an ongoing, open-label extension (OLE) of a Phase 2b study (X-TOLE) of azetukalner in adults with focal onset seizures (FOS) receiving 1-3 antiseizure medications. METHODS:Eligible participants enrolled in the 7-year OLE at 20 mg azetukalner once daily with food. Long-term seizure outcomes included median percentage change (MPC) in monthly (28 days) FOS frequency from the double-blind phase (DBP) baseline and achievement of ≥50%, ≥75%, ≥90%, and 100% seizure reductions. RESULTS:285 participants completed the DBP, and 275 (96.5%) enrolled in the OLE. At the 24-month interim analysis (September 5, 2023), 182 participants had been treated for ≥12 months and 165 for ≥24 months; 152 (55.3%) continued in the study. The median (range) treatment duration in the OLE was 26.3 (0.1-46.6) months. MPC reduction was 83.2% at 24 months in the OLE vs. DBP baseline. For all participants who entered the OLE, 56.4% (155/275) and 44.4% (122/275) achieved a ≥50% seizure reduction, 28.4% (78/275) and 19.6% (54/275) achieved a ≥90% seizure reduction, and 22.2% (61/275) and 14.9% (41/275) achieved seizure freedom (100% seizure reduction) for any consecutive ≥6- and ≥12-month period, respectively. For those who reached ≥24 months in the OLE, seizure freedom was achieved by 34.5% (57/165) and 23.6% (39/165) for any consecutive ≥6- and ≥12-month period, respectively. The majority of treatment-emergent adverse events (TEAEs) were mild or moderate. The most common TEAEs were dizziness (21.8%), headache (15.3%), coronavirus infection (15.3%), somnolence (12.7%), fall (12.7%), and memory impairment (10.9%). Serious AEs were reported in 35 (12.7%) participants. SIGNIFICANCE/CONCLUSIONS:The efficacy demonstrated by azetukalner in reducing FOS seizure frequency in the DBP was sustained in this interim analysis. Azetukalner was generally well tolerated, with no new safety signals compared to the DBP. These data suggest sustained long-term efficacy and safety of azetukalner in a difficult-to-treat population. PLAIN LANGUAGE SUMMARY/CONCLUSIONS:This long-term study assessed the safety and efficacy of azetukalner to treat focal seizures. Patients taking azetukalner daily with food for about 2 years had far fewer focal seizures with azetukalner than before taking the medication. For those who had been treated for 24 months, about a third were seizure-free for a consecutive 6-month period, and about a quarter were seizure-free for a consecutive 12-month period. Most side effects were mild or moderate, and these included dizziness, headache, and somnolence (sleepiness).