Faculty Bibliography

The insula is well established as an epileptogenic area.1 Insular epilepsy surgery demands precise anatomic knowledge2-4 and tailored removal of the epileptic zone with careful neuromonitoring.5 We present an operative video illustrating an intracranial electroencephalogram (EEG) depth electrode guided anterior insulectomy.  We report a 17-yr-old right-handed woman with a 4-yr history of medically refractory epilepsy. The patient reported daily nocturnal ictal vocalization preceded by an indescribable feeling. Preoperative evaluation was suggestive of a right frontal-temporal onset, but the noninvasive results were discordant. She underwent a combined intracranial EEG study with a frontal-parietal grid, with strips and depth electrodes covering the entire right hemisphere. Epileptiform activity was observed in contact 6 of the anterior insula electrode. The patient consented to the procedure and to the publication of her images.  A right anterior insulectomy was performed. First, a portion of the frontal operculum was resected and neuronavigation was used for the initial insula localization. However, due to unreliable neuronavigation (ie, brain shift), the medial and anterior borders of the insular resection were guided by the depth electrode reference. The patient was discharged 3 d after surgery with no neurological deficits and remains seizure free.  We demonstrate that depth electrode guided insular surgery is a safe and precise technique, leading to an optimal outcome.

OBJECTIVE:Generalized epileptiform discharges (GEDs) can occur during seizures or without obvious clinical accompaniment. Motor vehicle driving risk during apparently subclinical GEDs is uncertain. Our goals were to develop a feasible, realistic test to evaluate driving safety during GEDs, and to begin evaluating electroencephalographic (EEG) features in relation to driving safety. METHODS:Subjects were aged ≥15 years with generalized epilepsy, GEDs on EEG, and no clinical seizures. Using a high-fidelity driving simulator (miniSim) with simultaneous EEG, a red oval visual stimulus was presented every 5 minutes for baseline testing, and with each GED. Participants were instructed to pull over as quickly and safely as possible with each stimulus. We analyzed driving and EEG signals during GEDs. RESULTS:Nine subjects were tested, and five experienced 88 GEDs total with mean duration 2.31 ± 1.89 (SD) seconds. Of these five subjects, three responded appropriately to all stimuli, one failed to respond to 75% of stimuli, and one stopped driving immediately during GEDs. GEDs with no response to stimuli were significantly longer than those with appropriate responses (8.47 ± 3.10 vs 1.85 ± 0.69 seconds, P < .001). Reaction times to stimuli during GEDs were significantly correlated with GED duration (r = 0.30, P = .04). In addition, EEG amplitude was greater for GEDs with no response to stimuli than GEDs with responses, both for overall root mean square voltage amplitude (66.14 μV vs 52.99 μV, P = .02) and for fractional power changes in the frequency range of waves (P < .05) and spikes (P < .001). SIGNIFICANCE:High-fidelity driving simulation is feasible for investigating driving behavior during GEDs. GEDs with longer duration and greater EEG amplitude showed more driving impairment. Future work with a large sample size may ultimately enable classification of GED EEG features to predict individual driving risk.

The term 'implantation effect' is used to describe an immediate and transient improvement in seizure frequency following an intracranial study for seizure onset localization. We conducted a retrospective analysis of 190 consecutive patients undergoing intracranial electroencephalogram (EEG) monitoring, of whom 41 had no subsequent resection/ablation/stimulation; 33 had adequate data and follow-up time available for analysis. Analysis of seizure frequency following an intracranial study showed 36% (12/33) responder rate (>50% seizure reduction) at one year, decreasing and stabilizing at 20% from year 4 onwards. In addition, we describe three patients (9%) who had long term seizure freedom of more than five years following electrode implantation alone, two of whom had thalamic depth electrodes. Electrode implantation perhaps leads to a neuromodulatory effect sufficient enough to disrupt epileptogenic networks. Rarely, this may be significant enough to even result in long term seizure freedom, as seen in our three patients.

OBJECTIVE:Localization related epilepsy (LRE) is increasingly accepted as a network disorder. To better understand the network specific characteristics of LRE, we defined individual epilepsy networks and compared them across patients. METHODS:The epilepsy network was defined in the slow cortical potential frequency band in 10 patients using intracranial EEG data obtained during interictal periods. Cortical regions were included in the epilepsy network if their connectivity pattern was similar to the connectivity pattern of the seizure onset electrode contact. Patients were subdivided into frontal, temporal, and posterior quadrant cohorts according to the anatomic location of seizure onset. Jaccard similarity was calculated within each cohort to assess for similarity of the epilepsy network between patients within each cohort. RESULTS:All patients exhibited an epilepsy network in the slow cortical potential frequency band. The topographic distribution of this correlated network activity was found to be unique at the single subject level. CONCLUSIONS:The epilepsy network was unique at the single patient level, even between patients with similar seizure onset locations. SIGNIFICANCE:We demonstrated that the epilepsy network is patient-specific. This is in keeping with our current understanding of brain networks and identifies the patient-specific epilepsy network as a possible biomarker in LRE.

IMPORTANCE:Seizures recur in as many as half of patients who undergo surgery for drug-resistant temporal lobe epilepsy (TLE). Understanding why TLE is resistant to surgery in some patients may reveal insights into epileptogenic networks and direct new therapies to improve outcomes. OBJECTIVE:To characterize features of surgically refractory TLE. DESIGN, SETTING, AND PARTICIPANTS:Medical records from a comprehensive epilepsy center were retrospectively reviewed for 131 patients who received a standard anteromedial temporal resection by a single surgeon from January 1, 2000, to December 31, 2015. Thirteen patients were excluded for having less than 1 year of follow-up. Patients at the highest risk for seizure recurrence were identified. Intracranial electroencephalogram (iEEG) analyses generated 3-dimensional seizure spread representations and quantified rapid seizure spread. The final analyses of seizure outcome and follow-up data were performed in June 2017. MAIN OUTCOMES AND MEASURES:The Engel class seizure outcome following surgery was evaluated for all patients, defining seizure recurrence as Engel class II or greater. Intracranial recordings of neocortical grids/strips and depth electrodes were analyzed visually for seizure spread. Fast β power was projected onto reconstructions of patients' brain magnetic resonance imaging scans to visualize spread patterns and was quantified to compare power within vs outside resective margins. RESULTS:Of 118 patients with 1 year of follow-up or more (mean [SD], 6.5 [4.6] years), 66 (55.9%) were women and 52 (44.1%) were men (median age, 39 years [range, 4-66 years]). The cumulative probability of continuous Engel class I seizure freedom since surgery at postoperative year 10 and afterward was 65.6%, with 92% of recurrences in years 1 to 3. Multivariable statistical analyses found that the selection for iEEG study was the most reliable predictor of seizure recurrence, with a mixed-effects model estimating that the Engel score in the iEEG cohort was higher by a mean (SD) of 1.1 (0.33) (P = .001). In patients with iEEG results, rapid seizure spread in less than 10 seconds was associated with recurrence (hazard ratio, 5.99; 95% CI, 1.7-21.1; P < .01). In the first 10 seconds of seizures, fast β power activity outside the resective margins in the lateral temporal cortex was significantly greater in patients whose seizures recurred compared with patients who were seizure-free (mean [SEM], 137.5% [16.8%] vs 93.4% [4.6%]; P < .05). CONCLUSIONS AND SIGNIFICANCE:Rapid seizure spread outside anteromedial temporal resection resective margins plays a significant role in the surgical failure of drug-resistant TLE. Seizure control after epilepsy surgery might be improved by investigating areas of early spread as candidates for resection or neuromodulation.

OBJECTIVE:The objective of the study was to compare the performance of intravenous (IV) lorazepam (IVL) and intranasal midazolam (INM) for seizure termination and prevention of seizure clusters in adults admitted to the epilepsy monitoring unit (EMU) in whom seizures were captured on continuous video-electroencephalogram. METHODS:Retrospective cohort of consecutive adults (≥18 years) with epilepsy admitted to the EMU at a single tertiary academic center, who experienced epileptic seizures (confirmed electroencephalographically) and required rescue therapy. The study spanned from January 2015 until December 2016, which included one year before and one year after transitioning from IVL to INM as the standard rescue therapy at our institution. RESULTS:A total of 50 subjects received rescue therapy and were included in the analysis. In the first year, out of 216 patients with epilepsy admitted to the EMU, 27 (13%) received IVL; in the second year, 23/217 (11%) received INM. There were no differences in baseline characteristics and markers of epilepsy severity, the median duration of index seizure (1.7 min [interquartile range (IQR): 1.1-2.7] in IVL vs. 2.0 min [IQR: 1.5-2.6] in INM group, p = 0.20), or in the number of subjects requiring repeat benzodiazepine administrations (IVL 8/27 [29.6%] vs. INM 7/23 [30.4%], p = 0.95). There were no differences in the median number of recurrent seizures in 24 h (1 [IQR: 1-3] in IVL vs. 2 [IQR: 1-4] in INM, p = 0.27), occurrence of status epilepticus (IVL 4/27 [14.8%] subjects vs. INM 1/23 [4.3%] subjects, p = 0.36), incidence of seizure clusters (IVL 8/27 [29.6%] subjects vs. INM 7/23 [30.4%] subjects, p = 0.95), need for transfer to an intensive care unit (ICU), or other adverse events. SIGNIFICANCE:In our retrospective study, INM was comparable with IVL for seizure termination and prevention of seizure clusters in the adult EMU. Intranasal midazolam circumvents the need for IV access to be maintained throughout hospitalization and is an attractive alternative to IVL as a rescue therapy in this setting. Ideally, future large, prospective, randomized, and double blind studies are needed to confirm these findings.

Faciobrachial dystonic seizures and limbic encephalitis closely associate with antibodies to leucine-rich glioma-inactivated 1 (LGI1). Here, we describe 103 consecutive patients with faciobrachial dystonic seizures and LGI1 antibodies to understand clinical, therapeutic and serological differences between those with and without cognitive impairment, and to determine whether cessation of faciobrachial dystonic seizures can prevent cognitive impairment. The 22/103 patients without cognitive impairment typically had normal brain MRI, EEGs and serum sodium levels (P < 0.0001). Overall, cessation of faciobrachial dystonic seizures with antiepileptic drugs alone occurred in only 9/89 (10%) patients. By contrast, 51% showed cessation of faciobrachial dystonic seizures 30 days after addition of immunotherapy (P < 0.0001), with earlier cessation in cognitively normal patients (P = 0.038). Indeed, expedited immunotherapy (P = 0.031) and normal cognition (P = 0.0014) also predicted reduced disability at 24 months. Furthermore, of 80 patients with faciobrachial dystonic seizures as their initial feature, 56% developed cognitive impairment after 90 days of active faciobrachial dystonic seizures. Whereas only one patient developed cognitive impairment after cessation of faciobrachial dystonic seizures (P < 0.0001). All patients had IgG4-LGI1 antibodies, but those with cognitive impairment had higher proportions of complement-fixing IgG1 antibodies (P = 0.03). Both subclasses caused LGI1-ADAM22 complex internalization, a potential non-inflammatory epileptogenic mechanism. In summary, faciobrachial dystonic seizures show striking time-sensitive responses to immunotherapy, and their cessation can prevent the development of cognitive impairment.awx323media15681705685001.