David Diosy

Prevalence of benign epileptiform variants

OBJECTIVE There are numerous distinctive benign electroencephalographic (EEG) patterns which are morphologically epileptiform but are non-epileptic. The aim of this study was to determine the prevalence of different benign epileptiform variants (BEVs) among subjects who underwent routine EEG recordings in a large EEG laboratory over 35 years. METHODS We retrospectively studied the prevalence of BEVs among 35,249 individuals who underwent outpatient EEG recordings at London Health Sciences Centre in London, Ontario, Canada between January 1, 1972 and December 31, 2007. The definitions of the Committee on Terminology of the International Federation of Societies for EEG and Clinical Neurophysiology (IFSECN) were used to delineate epileptiform patterns (Chatrian et al. A glossary of terms most commonly used by clinical electroencephlographers. Electroenceph Clin Neurophysiol 1974;37:538-48) and the descriptions of Klass and Westmoreland [Klass DW, Westmoreland BF. Nonepileptogenic epileptiform electroenephalographic activity. Ann Neurol 1985;18:627-35] were used to categorize the BEVs. RESULTS BEVs were identified in 1183 out of 35,249 subjects (3.4%). The distribution of individual BEVs were as follows: benign sporadic sleep spikes 1.85%, wicket waves 0.03%, 14 and 6 Hz positive spikes 0.52%, 6 Hz spike-and-waves 1.02%, rhythmic temporal theta bursts of drowsiness 0.12%, and subclinical rhythmic electrographic discharge of adults in 0.07%. CONCLUSION The prevalence of six types of BEVs was relatively low among the Canadian subjects when compared to the reports from other countries. SIGNIFICANCE BEVs are relatively uncommon incidental EEG findings. Unlike focal epileptic spikes and generalized spike-and-waves, BEVs do not predict the occurrence of epilepsy. Accurate identification of the BEVs can avoid misdiagnosis and unnecessary investigations.

Early Treatment of a Progressive Rasmussen's Like Syndrome with Ganciclovir

BACKGROUND Escalating focal sensorimotor seizures, progressive neurologic deficit and cognitive decline with associated typical magnetic resonance imaging (MRI) findings or pathological confirmation constitute the syndrome of Rasmussens encephalitis. METHODS Three patients with this clinical scenario had long-term follow-up after being given the antiviral drug ganciclovir 10 mg/kg/day IV for ten days within one to three months of disease onset. RESULTS Seizures occurred at least hourly and were localized to the Rolandic region. The MRIs were normal in one patient and in two showed changes consistent with ongoing seizures. Two patients, one whose short-term outcome was reported previously, had immediate and sustained cessation of seizures and resolution of their neurologic deficit. One patient with seizures from both hemispheres did not respond and went on to hemispherectomy that confirmed chronic encephalitis. Seizures continued in five other patients treated 6 to 72 months after disease onset. CONCLUSION The sustained seizure control after ganciclovir in two of three patients suggests this drug may be effective when given early in the course of this subacute intractable focal epilepsy syndrome.

Functional MRI of neuronal activation in epilepsy patients with malformations of cortical development.

Malformations of cortical development are disturbances in brain formation that arise from abnormalities affecting the processes of cortical development. Surgical treatment of intractable epilepsy in patients with malformations of cortical development requires localization of both epileptogenic and eloquent cortices. Functional magnetic resonance imaging has been shown to detect the reorganization of activation patterns in such patients. The purpose of this study was to determine whether functional reorganization of the primary sensory and motor cortices occurs in patients with epileptogenic malformations of cortical development. Functional MRI data were obtained for 11 patients (four male, seven female) with a mean age of 36 years (range 18-55 years). The mean age at epilepsy onset was 23 years (range 3-55 years). Twelve healthy controls (six male, six female) with mean age of 33 years (range 28-51 years) were also recruited for comparison. High resolution anatomical MRI was used to confirm the presence and the location of the malformation. All imaging experiments were performed using a 3.0T Siemens Tim Trio whole body MRI. Each subject performed four block-paradigm fMRI experiments to study motor and sensory activation for each hand. A total of 132 image sets were collected for each paradigm over 5.5min (2.5s per image). Each paradigm consisted of seven stimulus periods lasting 30s (12 images) and stimulus onset of 30, 90, 150, 210 and 270s. Functional data were obtained from all eligible patients and compared to those of controls. Reorganization and reduction in function in the motor and sensory areas were observed in patients with cortical dysplasia. Patients with polymicrogyria did not present with significant functional reorganization and patients with heterotopias and coexisting polymicrogyria and/or cortical dysplasia had variable patterns of activation. In summary, this study showed evidence of functional reorganization of sensory and motor cortices in patients with cortical dysplasia development. Such information should be carefully considered in surgical planning and treatment.

Outcome of temporal lobe epilepsy surgery evaluated with bitemporal intracranial electrode recordings.

BACKGROUND Temporal lobe epilepsy (TLE) with unclear lateralization may require intracranial implantation of electrodes (IIE). We retrospectively assessed the association between the use of IIE and long-term outcomes in patients undergoing anterior temporal lobectomy (ATL). PARTICIPANTS AND METHODS We retrospectively reviewed the records of 1,032 patients undergoing epilepsy surgery at our center from 1977 to 2006. Patients who underwent ATL were included. Seizure outcome was assessed through final follow-up. Those who underwent scalp and IIE (mostly evaluated with temporal subdural strip electrodes) were compared. RESULTS From 497 patients who underwent ATL, 139 did so after IIE placement in the temporal lobes. Mean age at surgery was 32.3±12.3years and median duration of follow-up 24 months (range: 6-36). Fifty-three percent of those evaluated with IIE were seizure-free at their last available visit (vs. 68% evaluated with only scalp EEG, p=0.002). Patients with lesional TLE generally had a better outcome (65.5% seizure free) than those without lesions (56.3%, p=0.093), especially for unilateral TLE diagnosed with IIE. In a multivariate Cox regression analyses adjusted for gender, neuropsychological concordance, pathological findings, and post-operative seizures, bilateral TLE predicted seizure recurrence in IIE patients (HR=2.08, 95% CI: 1.08-4.0, p=0.029). CONCLUSIONS More than a half of those who undergo IIE in suspected TLE are seizure free after ATL. IIE allows for the identification of surgical candidates.

Coprolalia as a manifestation of epileptic seizures

OBJECTIVE The aim of this study was to investigate the lateralizing and localizing value of ictal coprolalia and brain areas involved in its production. METHODS A retrospective search for patients manifesting ictal coprolalia was conducted in our EMU database. Continuous video-EEG recordings were reviewed, and EEG activity before and during coprolalia was analyzed using independent component analysis (ICA) technique and was compared to the seizures without coprolalia among the same patients. RESULTS Nine patients were evaluated (five women), eight with intracranial video-EEG recordings (icVEEG). Four had frontal or temporal lesions, and five had normal MRIs. Six patients showed impairment in the language functions and five in the frontal executive tasks. Two hundred six seizures were reviewed (60.7% from icVEEG). Ictal coprolalia occurred in 46.6% of them, always associated with limbic auras or automatisms. They arose from the nondominant hemisphere in five patients, dominant hemisphere in three, and independently from the right and left hippocampus-parahippocampus in one. Electroencephalographic activity always involved orbitofrontal and/or mesial temporal regions of the nondominant hemisphere when coprolalia occurred. Independent component analysis of 31 seizures in seven patients showed a higher number of independent components in the nondominant hippocampus-parahippocampus before and during coprolalia and in the dominant lateral temporal region in those seizures without coprolalia (p=0.009). Five patients underwent surgery, and all five had an ILAE class 1 outcome. SIGNIFICANCE Ictal coprolalia occurs in both males and females with temporal or orbitofrontal epilepsy and has a limited lateralizing value to the nondominant hemisphere but can be triggered by seizures from either hemisphere. It involves activation of the paralimbic temporal-orbitofrontal network.

T05. Pre-surgical assessment of drug-resistant insular and peri insular epilepsy: A single center experience

Introduction Epilepsy arising from the insula is widely regarded as a challenging type of seizure, probably owing to the deep-seated location of the insula and the extensive connections it makes with adjacent structures. In recent years, we have rapidly gained insights into insular epilepsy-related obstacles. Here, we describe a detailed analysis of the electro-clinical manifestations of this type of epilepsy using intra-cerebral recordings performed with Stereo-electroencephalography (SEEG). Methods We retrospectively analyzed 12 patients from our epilepsy program who underwent insular exploration using SEEG between June 2013 and June 2017. Patient information reviewed included demographics, clinical history, neurological examination; neuroimaging studies (Brain MRI, PET, Ictal SPECT), Scalp video-EEG, intracranial recordings with SEEG, histopathological findings, and surgical outcomes. Results 12 patients (M:F = 4:8; mean age, 32.5 years; range, 19–60 years) were found with seizures originating from either the insula alone or simultaneously originating from the insula and adjacent structures. One patient had a family history of epilepsy and another one had previous exposure to viral meningoencephalitis. Six patients had undergone prior surgery for epilepsy treatment. The mean seizure frequency was 4 seizures per week, and one patient experienced seizures daily. The most common aura was somatosensory sensation, followed by cephalic sensation in 4 and 3 patients, respectively. The commonest type of seizure was focal with impaired awareness in 10 patients. 50% of the patients showed a tendency for secondary generalizations, and 25% showed nocturnal predominance. Lesions were observed on brain MRI in 8 cases. Scalp EEG revealed different interictal discharge distributions: 5 patients showed localized frontotemporal spikes, 3 showed bilateral temporal spikes, and no spikes were detected in 4. The location of ictal onset could be localized in only 50% of patients. The most common scalp EEG ictal pattern was rhythmic delta activity (1–3 Hz). Subsequent SEEG showed six patients found to have a combination of clinical and subclinical seizures. SEEG clinical seizure onset from the insula alone was found in 50% of the patients (3 right, 2 left, 1 bilateral). The other patients presented with simultaneous onset from the insula and adjacent structures: 4 from mesial temporal structures, 1 temporal operculum, and 1 frontal operculum. The commonest SEEG ictal pattern was low voltage fast activity in 8 patients. Surgical resections guided by SEEG findings were performed in 5 patients and led to excellent outcomes; all these cases had Engle class 1 outcome at 6–24 months follow up. Conclusion We observed that it is not uncommon for seizures to simultaneously originate from the insula and adjacent structures. However, non-invasive EEG monitoring tools are likely insufficient to detect such simultaneous seizures. For the given sample, SEEG proved beneficial in providing optimal surgical outcomes.

Intracranial Electroencephalographic Monitoring: From Subdural to Depth Electrodes.

At the London Health Sciences Centre Epilepsy Program, stereotactically implanted depth electrodes have largely replaced subdural electrodes in the presurgical investigation of patients with drug-resistant epilepsy over the past 4 years. The rationale for this paradigm shift was more experience with, and improved surgical techniques for, stereoelectroencephalography, a possible lower-risk profile for depth electrodes, better patient tolerability, shorter operative time, as well as increased recognition of potential surgical targets that are not accessible to subdural electrodes.