Rasmussen's encephalitis: structural, functional, and clinical correlates of contralesional epileptiform activity.

Progressive inflammation of one hemisphere characterises Rasmussen's encephalitis (RE), but contralesional epileptiform activity has been repeatedly reported. We aimed to quantify contralesional epileptiform activity in RE and uncover its functional and structural underpinnings. We retrospectively ascertained people with RE treated between 2000 and 2018 at a tertiary centre (Centre 1) and reviewed all available EEG datasets. The temporal occurrence of preoperative contralesional epileptiform activity (interictal/ictal) was evaluated using mixed-effects logistic regression. Cases with/without contralesional epileptiform activity were compared for cognition, inflammation (ipsilesional brain biopsies), and MRI (cortical and fixel-based morphometry). EEG findings were validated in a second cohort treated at another tertiary centre (Centre 2) between 1995 and 2020. We included 127 people with RE and 687 EEG samples. Preoperatively, contralesional epileptiform activity was seen in 30/68 (44%, Centre 1) and 8/59 (14%, Centre 2). In both cohorts, this activity was associated with younger onset age (OR = 0.9; 95% CI 0.83-0.97; P = 0.006). At centre 1, contralesional epileptiform activity was associated with contralesional MRI alterations, lower intelligence (OR = 5.19; 95% CI 1.28-21.08; P = 0.021), and impaired verbal memory (OR = 10.29; 95% CI 1.97-53.85; P = 0.006). After hemispherotomy, 11/17 (65%, Centre 1) and 28/37 (76%, Centre 2) were seizure-free. Contralesional epileptiform activity was persistent postoperatively in 6/12 (50%, Centre 1) and 2/34 (6%, Centre 2). Preoperative contralesional epileptiform activity reduced the chance of postoperative seizure freedom in both cohorts (OR = 0.69; 95% CI 0.50-0.95; P = 0.029). Our findings question the concept of strict unilaterality of RE and provide the evidence of contralesional epileptiform activity as a possible EEG predictor for persisting postoperative seizures.

Evaluating the longer-term cognitive effects of adjunctive perampanel compared to lacosamide in a naturalistic outpatient setting.

PURPOSE: This retrospective longitudinal study aims to compare the longer-term cognitive and behavioral side effects of adjunctive antiepileptic treatment with perampanel (PER) and lacosamide (LCM), two third generation antiepileptic drugs with suggested favorable cognitive profiles. The two drugs were monitored according to a previously established routine diagnostic protocol (Helmstaedter et al. E&B 2013;26:182-7) which facilitates the retrospective comparison of antiepileptic drug tolerability in a naturalistic outpatient setting. METHODS: Records from 94 patients were evaluated who underwent neuropsychological assessment before and under adjunctive treatment with either PER (n = 57) or LCM (n = 37). Cognition was assessed using the EpiTrack screening for executive functions and a VLMT short form for verbal memory. Subjective assessments included a German QOLIE-10 adaptation (quality of life) and an extended Adverse Events Profile (AEP). The median follow-up interval was 36 weeks. RESULTS: Multivariate repeated measures statistics revealed a non-significant trend towards an interaction effect "time - treatment arm" on both executive function and memory. When analyzed separately executive functions and memory scores significantly improved under LCM (t = -2.76 p < 0.01 and t = -2.44 p < 0.05 respectively). Subjectively, PER was associated with improvements in 2/18 physiological domains and in the LCM group 1/9 cognitive domains deteriorated. Seizure freedom was achieved for five patients treated with LCM (14%) and 15 treated with PER (26%, χ2 = 2.2, n.s.). CONCLUSION: In a naturalistic outpatient setting, chronic adjunctive treatment with PER and LCM did not negatively affect cognition and LCM may even improve cognition. Neither drug increased self-reported irritability or aggression. This suggests favorable longer-term tolerability.

Mitochondrial dysfunction due to Leber's hereditary optic neuropathy as a cause of visual loss during assessment for epilepsy surgery.

Assessment for epilepsy surgery may require invasive measures such as implantation of intracranial electrodes or the Wada test. These investigations are commonly well tolerated. However, complications, including visual disturbances of various etiologies, have been reported. Here we describe two patients with pharmacoresistant temporal lobe epilepsy (TLE) who displayed loss of vision in the context of presurgical assessment and in whom mutations associated with Leber's hereditary optic neuropathy (LHON) were detected. Genetic analysis revealed in one patient the frequent mitochondrial G11778A LHON mutation in ND4. In the second patient, the mitochondrial C4640A mutation in ND2 was detected. This rare LHON mutation enhanced the sensitivity of the patient's muscle and brain tissue to amobarbital, a known blocker of the mitochondrial respiratory chain. Mitochondrial dysfunction has been reported in epilepsy. Thus, the presence of LHON mutations can be a rare cause of visual disturbances in patients with epilepsy and may have predisposed to development of epilepsy.