Gray Matter Sampling Differences Between Subdural Electrodes and Stereoelectroencephalography Electrodes.

Objective: Stereoelectroencephalography (SEEG) has seen a recent increase in popularity in North America; however, concerns regarding the spatial sampling capabilities of SEEG remain. We aimed to quantify and compare the spatial sampling of subdural electrode (SDE) and SEEG implants. Methods: Patients with drug-resistant epilepsy who underwent invasive monitoring were included in this retrospective case-control study. Ten SEEG cases were compared with ten matched SDE cases based on clinical presentation and pre-implantation hypothesis. To quantify gray matter sampling, MR and CT images were coregistered and a 2.5mm radius sphere was superimposed over the center of each electrode contact. The estimated recording volume of gray matter was defined as the cortical voxels within these spherical models. Paired t-tests were performed to compare volumes and locations of SDE and SEEG recording. A Ripley's K-function analysis was performed to quantify differences in spatial distributions. Results: The average recording volume of gray matter by each individual contact was similar between the two modalities. SEEG implants sampled an average of 20% more total gray matter, consisted of an average of 17% more electrode contacts, and had 77% more of their contacts covering gray matter within sulci. Insular coverage was only achieved with SEEG. SEEG implants generally consist of discrete areas of dense local coverage scattered across the brain; while SDE implants cover relatively contiguous areas with lower density recording. Significance: Average recording volumes per electrode contact are similar for SEEG and SDE, but SEEG may allow for greater overall volumes of recording as more electrodes can be routinely implanted. The primary difference lies in the location and distribution of gray matter than can be sampled. The selection between SEEG and SDE implantation depends on sampling needs of the invasive implant.

Consequences of mesial temporal sparing temporal lobe surgery in medically refractory epilepsy.

OBJECTIVE: We compared long-term seizure outcome, neuropsychological outcome, and occupational outcome of anterior temporal lobectomy (ATL) with and without sparing of mesial structures to determine whether mesial sparing temporal lobectomy prevents memory decline and thus disability, with acceptable seizure outcome. METHODS: We studied patients (n = 21) and controls (n = 21) with no evidence of mesial temporal sclerosis (MTS) on MRI who had surgery to treat drug-resistant epilepsy. Demographic and pre- and postsurgical clinical characteristics were compared. Patients had neuropsychological assessment before and after surgery. Neuropsychological analyses were limited to patients with left-sided surgery and available data (n = 14 in each group) as they were at risk of verbal memory impairment. The California Verbal Learning Test II (CVLT-II) (sum of trials 1-5, delayed free recall) and the Logical Memory subtest of the Wechsler Memory Scale III or IV (WMS-III or WMS-IV) (learning and delayed recall of prose passages) were used to assess verbal episodic learning and memory. Seizure and occupational outcomes were assessed. RESULTS: The chance of attaining seizure freedom was similar in the two groups, so sparing mesial temporal structures did not lessen the chance of stopping seizures. Sparing mesial temporal structures mitigated the extent of postoperative verbal memory impairment, though some of these individuals suffered decline as a consequence of surgery. Occupational outcome was similar in both groups. SIGNIFICANCE: Mesial temporal sparing resections provide a similar seizure outcome as ATL, while producing a better memory outcome. Anterior temporal lobectomy including mesial structure resection did not increase the risk of postoperative disability.

Pregnancy outcomes of refractory epilepsy patients treated with Brain-responsive neurostimulation.

OBJECTIVE: To study the pregnancy outcomes, including obstetric complications and fetal outcomes, in pregnant women with epilepsy (WWE) treated with direct brain-responsive neurostimulation (RNS System). METHODS: Retrospective review of obstetric outcomes and fetal outcomes in WWE treated with the RNS System at nine comprehensive epilepsy centers in the United States from 2014-2020. In addition, changes in seizure frequency, anti-seizure medications, and RNS System setting adjustments during pregnancy were investigated. RESULTS: A total of 10 subjects and 14 pregnancies were identified. The mean age at conception was 30.6 ± 4.3 years old. The mean age at implantation was 29.8 ± 4.4 years old. The mean stimulation charge densities ranged from 1.0 to 3.0 µC/cm2 during pregnancy. Obstetric complications included recurrent miscarriage (1 patient), cesarean section (3 patients) due to preeclampsia, non-reassuring fetal heart rate tracing or prolonged labor, preterm birth (1 patient), and preeclampsia (1 patient). No still birth, gestational hypertension, gestational diabetes, eclampsia, or maternal mortality were observed. No RNS System-exposed pregnancies had major congenital malformations. One offspring had a minor congenital anomaly of cryptorchidism in a pregnancy complicated with risk factors of advanced maternal age and bicornuate uterus. SIGNIFICANCE: The present study is the first report of RNS System-exposed pregnancies in WWE to date. No major congenital malformations were identified. All of the obstetric complications were within the expected range of those in WWE based on previously published data. The sample size of our study is small, so accumulation of additional cases will further help depict the safety profile of treatment with the RNS System during pregnancy.

Progressive myoclonic epilepsy: myoclonic epilepsy and ataxia due to KCNC1 mutation (MEAK): a case report and review of the literature.

Progressive myoclonic epilepsy (PME) is characterized by prominent myoclonus and generalized or focal seizures. A recently described novel KCNC1 mutation is associated with a specific phenotype of progressive myoclonic epilepsy, which has been defined as myoclonic epilepsy and ataxia due to potassium channel mutation (MEAK). Our case illustrates a typical presentation of this disease and the potential for misdiagnosis as idiopathic generalized epilepsy during the early phase of the disease. Unique findings that may suggest an alternative diagnosis are a progressive myoclonus, prominent ataxia/dysmetria on examination, and abnormally high amplitude in the sensory evoked potential recording. We also report a brief review of the existing literature on MEAK. Early and accurate diagnosis with genetic testing may significantly help in counseling patients and families.

Nine-year prospective efficacy and safety of brain-responsive neurostimulation for focal epilepsy.

OBJECTIVE: To prospectively evaluate safety and efficacy of brain-responsive neurostimulation in adults with medically intractable focal onset seizures (FOS) over 9 years. METHODS: Adults treated with brain-responsive neurostimulation in 2-year feasibility or randomized controlled trials were enrolled in a long-term prospective open label trial (LTT) to assess safety, efficacy, and quality of life (QOL) over an additional 7 years. Safety was assessed as adverse events (AEs), efficacy as median percent change in seizure frequency and responder rate, and QOL with the Quality of Life in Epilepsy (QOLIE-89) inventory. RESULTS: Of 256 patients treated in the initial trials, 230 participated in the LTT. At 9 years, the median percent reduction in seizure frequency was 75% (p < 0.0001, Wilcoxon signed rank), responder rate was 73%, and 35% had a ≥90% reduction in seizure frequency. We found that 18.4% (47 of 256) experienced ≥1 year of seizure freedom, with 62% (29 of 47) seizure-free at the last follow-up and an average seizure-free period of 3.2 years (range 1.04-9.6 years). Overall QOL and epilepsy-targeted and cognitive domains of QOLIE-89 remained significantly improved (p < 0.05). There were no serious AEs related to stimulation, and the sudden unexplained death in epilepsy (SUDEP) rate was significantly lower than predefined comparators (p < 0.05, 1-tailed χ2). CONCLUSIONS: Adjunctive brain-responsive neurostimulation provides significant and sustained reductions in the frequency of FOS with improved QOL. Stimulation was well tolerated; implantation-related AEs were typical of other neurostimulation devices; and SUDEP rates were low. CLINICALTRIALSGOV IDENTIFIER: NCT00572195. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that brain-responsive neurostimulation significantly reduces focal seizures with acceptable safety over 9 years.

A Randomized Controlled Trial for Veterans with PTSD and Substance Use Disorder: Creating Change versus Seeking Safety.

BACKGROUND: Posttraumatic stress disorder (PTSD) and substance use disorder (SUD) co-occur in military veterans and other populations. OBJECTIVE: To conduct a randomized controlled trial to compare a new past-focused treatment (Creating Change; CC), to a well-established, evidence-based present-focused treatment for PTSD/SUD (Seeking Safety; SS), on symptoms of both disorders. CC guides patients to process the past through exploration of PTSD/SUD life themes and memories whereas SS focuses on coping skills in the present. METHODS: Fifty-two male and female veterans with current PTSD/SUD were randomized (n = 26 per treatment) and assessed at baseline, end-of-treatment and 3-month follow-up. They received 17 individual one-hour sessions. RESULTS: Intent-to-treat analyses indicated that both conditions improved over time, with no difference between conditions, on PTSD, alcohol use, and drug use (our primary outcomes) as well as mental health symptoms, quality of life, self-efficacy, and SUD cognitions. Effect sizes were medium except for alcohol use, which was large. Change over time reflected improvement from baseline to end-of-treatment, with gains sustained at follow-up, although alcohol use showed continued improvement from end-of-treatment to follow-up. Both treatments evidenced a strong safety profile; and attendance, alliance, and treatment satisfaction were also very strong. Conclusions/importance: CC has promise as a PTSD/SUD therapy with strong public health relevance and the potential to fill important gaps in the field. We used minimal exclusionary criteria to obtain a real-world sample, which was severe-predominantly substance-dependent with chronic PTSD and additional psychiatric diagnoses. Future research is warranted, especially on nonveteran samples and treatment mechanisms of action.

Atlas of Electroencephalography, 3rd Edition.

Electroencephalography (EEG) is the recording of the electrical activity of the brain. EEG is a reliable test to assess cerebral function. It aids in diagnosis, classification, and management of patients with epilepsy. It also has practical uses in conditions other than epilepsy. Moreover, it is harmless and inexpensive. EEG is an important tool for evaluating patients with epilepsy. It may help classify the syndrome, identify the likely source of focal seizures, and confirm a diagnosis of status epilepticus. EEG is therefore helpful when selecting appropriate antiepileptic drugs for patients with epilepsy, is valuable for diagnosis and management of status epilepticus as well as predicting the prognosis in epilepsy syndromes, and, is finally useful when localizing an area for resection in surgery candidates. In addition, despite advances in neuroimaging, EEG remains a valuable tool in the evaluation of stuporous and comatose patients. A systematic approach is essential for EEG interpretation, and when combined with good clinical judgment, it will improve diagnostic sensitivity and specificity and may improve therapeutic outcomes. This EEG atlas is designed as a practical guide for neurology residents, neurologists, and epileptologists, so that they may appropriately identify normal and abnormal findings, while reading an EEG. By reading and reviewing the relevant chapter of this well-organized atlas, that includes many EEG images, the reader will also learn how to report an EEG finding. We hope that this atlas fills an unmet need, and leads to improved patient care.

AR2, a novel automatic muscle artifact reduction software method for ictal EEG interpretation: Validation and comparison of performance with commercially available software.

Objective: To develop a novel software method (AR2) for reducing muscle contamination of ictal scalp electroencephalogram (EEG), and validate this method on the basis of its performance in comparison to a commercially available software method (AR1) to accurately depict seizure-onset location. Methods: A blinded investigation used 23 EEG recordings of seizures from 8 patients. Each recording was uninterpretable with digital filtering because of muscle artifact and processed using AR1 and AR2 and reviewed by 26 EEG specialists. EEG readers assessed seizure-onset time, lateralization, and region, and specified confidence for each determination. The two methods were validated on the basis of the number of readers able to render assignments, confidence, the intra-class correlation (ICC), and agreement with other clinical findings. Results: Among the 23 seizures, two-thirds of the readers were able to delineate seizure-onset time in 10 of 23 using AR1, and 15 of 23 using AR2 (p<0.01). Fewer readers could lateralize seizure-onset (p<0.05). The confidence measures of the assignments were low (probable-unlikely), but increased using AR2 (p<0.05). The ICC for identifying the time of seizure-onset was 0.15 (95% confidence interval (CI), 0.11-0.18) using AR1 and 0.26 (95% CI 0.21-0.30) using AR2.  The EEG interpretations were often consistent with behavioral, neurophysiological, and neuro-radiological findings, with left sided assignments correct in 95.9% (CI 85.7-98.9%, n=4) of cases using AR2, and 91.9% (77.0-97.5%) (n=4) of cases using AR1. Conclusions: EEG artifact reduction methods for localizing seizure-onset does not result in high rates of interpretability, reader confidence, and inter-reader agreement. However, the assignments by groups of readers are often congruent with other clinical data. Utilization of the AR2 software method may improve the validity of ictal EEG artifact reduction.

Brain-responsive neurostimulation in patients with medically intractable mesial temporal lobe epilepsy.

OBJECTIVE: Evaluate the seizure-reduction response and safety of mesial temporal lobe (MTL) brain-responsive stimulation in adults with medically intractable partial-onset seizures of mesial temporal lobe origin. METHODS: Subjects with mesial temporal lobe epilepsy (MTLE) were identified from prospective clinical trials of a brain-responsive neurostimulator (RNS System, NeuroPace). The seizure reduction over years 2-6 postimplantation was calculated by assessing the seizure frequency compared to a preimplantation baseline. Safety was assessed based on reported adverse events. RESULTS: There were 111 subjects with MTLE; 72% of subjects had bilateral MTL onsets and 28% had unilateral onsets. Subjects had one to four leads placed; only two leads could be connected to the device. Seventy-six subjects had depth leads only, 29 had both depth and strip leads, and 6 had only strip leads. The mean follow-up was 6.1 ± (standard deviation) 2.2 years. The median percent seizure reduction was 70% (last observation carried forward). Twenty-nine percent of subjects experienced at least one seizure-free period of 6 months or longer, and 15% experienced at least one seizure-free period of 1 year or longer. There was no difference in seizure reduction in subjects with and without mesial temporal sclerosis (MTS), bilateral MTL onsets, prior resection, prior intracranial monitoring, and prior vagus nerve stimulation. In addition, seizure reduction was not dependent on the location of depth leads relative to the hippocampus. The most frequent serious device-related adverse event was soft tissue implant-site infection (overall rate, including events categorized as device-related, uncertain, or not device-related: 0.03 per implant year, which is not greater than with other neurostimulation devices). SIGNIFICANCE: Brain-responsive stimulation represents a safe and effective treatment option for patients with medically intractable epilepsy, including patients with unilateral or bilateral MTLE who are not candidates for temporal lobectomy or who have failed a prior MTL resection.

Brain-responsive neurostimulation in patients with medically intractable seizures arising from eloquent and other neocortical areas.

OBJECTIVE: Evaluate the seizure-reduction response and safety of brain-responsive stimulation in adults with medically intractable partial-onset seizures of neocortical origin. METHODS: Patients with partial seizures of neocortical origin were identified from prospective clinical trials of a brain-responsive neurostimulator (RNS System, NeuroPace). The seizure reduction over years 2-6 postimplantation was calculated by assessing the seizure frequency compared to a preimplantation baseline. Safety was assessed based on reported adverse events. Additional analyses considered safety and seizure reduction according to lobe and functional area (e.g., eloquent cortex) of seizure onset. RESULTS: There were 126 patients with seizures of neocortical onset. The average follow-up was 6.1 implant years. The median percent seizure reduction was 70% in patients with frontal and parietal seizure onsets, 58% in those with temporal neocortical onsets, and 51% in those with multilobar onsets (last observation carried forward [LOCF] analysis). Twenty-six percent of patients experienced at least one seizure-free period of 6 months or longer and 14% experienced at least one seizure-free period of 1 year or longer. Patients with lesions on magnetic resonance imaging (MRI; 77% reduction, LOCF) and those with normal MRI findings (45% reduction, LOCF) benefitted, although the treatment response was more robust in patients with an MRI lesion (p = 0.02, generalized estimating equation [GEE]). There were no differences in the seizure reduction in patients with and without prior epilepsy surgery or vagus nerve stimulation. Stimulation parameters used for treatment did not cause acute or chronic neurologic deficits, even in eloquent cortical areas. The rates of infection (0.017 per patient implant year) and perioperative hemorrhage (0.8%) were not greater than with other neurostimulation devices. SIGNIFICANCE: Brain-responsive stimulation represents a safe and effective treatment option for patients with medically intractable epilepsy, including adults with seizures of neocortical onset, and those with onsets from eloquent cortex.

Absolute spike frequency as a predictor of surgical outcome in temporal lobe epilepsy.

PURPOSE: Frequent interictal epileptiform abnormalities may correlate with poor prognosis after temporal lobe resection for refractory epilepsy. To date, studies have focused on limited resections such as selective amygdalohippocampectomy and apical temporal lobectomy without hippocampectomy. However, it is unclear whether the frequency of spikes predicts outcome after standard anterior temporal lobectomy. METHOD: Preoperative scalp video-EEG monitoring data from patients who subsequently underwent anterior temporal lobectomy over a three year period and were followed for at least one year were reviewed for the frequency of interictal epileptiform abnormalities. Surgical outcome for those patients with frequent spikes (>60/h) was compared with those with less frequent spikes. Additionally, spike frequency was evaluated as a continuous variable and correlated with outcome to determine if increased spike frequency correlated with worse outcome, as assessed by modified Engel Class outcome. RESULTS: Forty-seven patients (18 men, 29 women; mean age 40 years at surgery) were included. Forty-six patients had standard anterior temporal lobectomy (24 right, 22 left) and one had a modified left temporal lobectomy. There was no significant difference in seizure outcome between those with frequent (57% Class I) vs. those with less frequent (58% Class I) spikes. Increased spike frequency did not correlate with worse outcome. Greater than 20 complex partial seizures/month and generalized tonic-clonic seizures within one year of surgery correlated with worse outcome. CONCLUSIONS: This study suggests that absolute spike frequency does not predict seizure outcome after anterior temporal lobectomy unlike in selective procedures, and should not be used as a prognostic factor in this population.

JOURNAL CLUB: Longitudinal Qualitative Characterization of MRI Features After Laser Interstitial Thermal Therapy in Drug-Resistant Epilepsy.

OBJECTIVE: Laser interstitial thermal therapy (LITT), a method for ablating brain tissue under real-time MR thermometry, has been used more frequently in recent years to treat nonmalignant lesions. The purpose of this study is to longitudinally characterize MRI features after LITT in patients with drug-resistant epilepsy, primarily in the setting of mesial temporal sclerosis. MATERIALS AND METHODS: MR images from 23 consecutive patients who underwent LITT were retrospectively reviewed. All patients had images obtained immediately after the ablation. Multiple patients had follow-up imaging at various time points after treatment, from postoperative days 7 through 1539. A total of 54 MRI studies were reviewed. RESULTS: Immediately after LITT, MR images showed a ring-enhancing lesion at the ablation site with minimal surrounding edema. Seven images showed increased enhancement of the ipsilateral choroid plexus. Images in the subacute phase showed a mild increase in edema with similar enhancement. Images in the transitional phase showed a decrease in edema with variable enhancement. Images in the chronic phase showed minimal gliosis with or without cavity formation or cavity formation alone, with either decreased or no enhancement. CONCLUSION: This report describes the time course of the imaging findings after LITT for drug-resistant epilepsy. The typical stages include rim-enhancing lesion with minimal edema, followed by an increase in edema, to eventual gliosis and nonenhancing cavity formation. Radiologists need to be familiar with the postablation findings to minimize misdiagnosis and prevent unnecessary workup.

Clinical features and postoperative seizure outcome in patients with drug-resistant gelastic seizures without hypothalamic hamartoma.

OBJECTIVES: The objective of this study was to describe the clinical characteristics and surgical outcome in patients with gelastic seizures without hypothalamic hamartoma. METHODS: We retrospectively reviewed all the video-EEG reports over a 5-year period (2007-2011) for the occurrence of the terms "laugh" or "giggle" in the text body. All the patients with at least one documented gelastic seizure at the epilepsy monitoring unit were studied. In patients who underwent epilepsy surgery, seizure outcomes were analyzed. RESULTS: Sixteen patients (10 females and 6 males) with a mean age of 46.3years were studied. Seven patients had invasive intracranial EEG recordings. Seizure onset zone was in a temporal lobe in four patients and the frontal lobe in one patient. Two patients did not have gelastic seizures during their intracranial EEG monitoring. Nine patients underwent resective epilepsy surgery for their seizures. Six patients (67%) were seizure-free after surgery. CONCLUSION: In adult patients, gelastic seizures can be seen in patients with focal epilepsy without hypothalamic hamartoma. Nonhypothalamic hamartoma gelastic seizures originating from the temporal lobe can be amenable to surgery.

Seizure outcome after switching antiepileptic drugs: A matched, prospective study.

OBJECTIVE: Outcomes after changing antiepileptic drugs (AEDs) have largely been studied in single cohort series. We recently reported the first study to examine this question in a controlled manner. Here we expand on these results by using a matched, prospective methodology applied to both uncontrolled and well-controlled patients taking any AED. METHODS: We reviewed all outpatient notes over a 9-month period and identified patients with focal epilepsy who were on monotherapy. We classified those who switched AEDs as case patients, with those remaining on the same drug serving as controls. We matched cases with controls for seizure status (seizure-free in the preceding 6 months or not), current AED, and number of failed AEDs. We subsequently assessed outcome 6 months later. RESULTS: Seizure-free patients who switched drug (n = 12) had a 16.7% rate of seizure recurrence at 6 months, compared to 2.8% among controls remaining on the same drug (n = 36, p = 0.11). There was a 37% remission rate among uncontrolled patients who switched drug compared to 55.6% among controls (n = 27 per group, p = 0.18). Uncontrolled patients who had previously tried more than one AED were somewhat less likely to enter remission (p = 0.057). Neither AED mechanism of action nor change in dosage impacted outcome. SIGNIFICANCE: Herein we provide further estimation of the modest risk (~14%) associated with switching AEDs in patients in remission compared to being maintained on the same regimen. Uncontrolled patients were no more likely to enter remission after a drug switch than they were after remaining on the same drug, suggesting that spontaneous changes in disease state, and not drug response, underlie remission in this population.

Long-term effect of antiepileptic drug switch on serum lipids and C-reactive protein.

BACKGROUND: Prior studies have shown that switching patients from inducing antiepileptic drugs (AEDs) to lamotrigine, levetiracetam, or topiramate reduces serum lipids and C-reactive protein (CRP). These studies were all of short duration, and some drugs, such as zonisamide, have not been investigated. METHODS: We recruited 41 patients taking phenytoin or carbamazepine who were being switched to zonisamide, lamotrigine, or levetiracetam. We measured serum lipids and CRP before the switch, >6weeks after, and >6months after. An untreated control group (n=14) underwent similar measurement. We combined these data with those of our previous investigation (n=34 patients and 16 controls) of a very similar design. RESULTS: There were no differences in outcome measures between the two inducing AEDs nor among the three noninducing AEDs. Total cholesterol (TC), atherogenic lipids, and CRP were higher under inducer treatment than in controls. All measures were elevated under inducer treatment relative to noninducer treatment, including TC (24mg/dL higher, 95% CI: 17.5-29.9, p<0.001) and CRP (72% higher, 95% CI: 41%-111%, p<0.001). The difference between drug treatments was clinically meaningful for atherogenic lipids (16%, 95% CI: 11%-20%, p<0.001) but small for high-density lipoprotein cholesterol (5%, 95% CI: 1%-9%, p<0.05). All measures were stable between 6weeks and 6months after drug switch. CONCLUSIONS: We demonstrate that switching from inducing to noninducing AEDs produces an enduring reduction in serum lipids and CRP. These results provide further evidence that inducing AEDs may be associated with elevated vascular disease risk. These are the first vascular risk marker data in patients taking zonisamide, which shows a profile similar to that of other noninducing AEDs.

Heart rate and blood pressure in sudden unexpected death in epilepsy (SUDEP).

Epilepsy is associated with interictal and ictal autonomic dysfunction. Seizures can immediately cause increases in blood pressure (BP) and heart rate (HR). However, it is unknown whether uncontrolled seizures, particularly when frequent, might chronically elevate the BP or HR. Additionally, it is unknown whether the interictal BP and HR is altered in individuals who are at risk for SUDEP, compared with other individuals with epilepsy. SUDEP often occurs in patients with highly refractory epilepsy. Such individuals might be at risk for a state of chronically heightened sympathetic tone, which might affect the HR and BP interictally. This study compared the resting awake interictal HR and BP in individuals who subsequently died due to SUDEP and compared these to HR and BP in two control epilepsy groups (refractory and controlled). While the overall HR and BP are similar between groups, there is a trend toward a higher diastolic BP and more stable HR in individuals who subsequently died due to SUDEP, compared with epilepsy controls. These data suggest that there may be specific types of interictal autonomic dysfunction in individuals at risk for SUDEP. Such abnormalities might serve as markers for those at elevated risk for SUDEP.

Adult Focal Epilepsies.

PURPOSE OF REVIEW: Focal epilepsy is the most common type of epilepsy in adulthood. This article discusses the seizure symptomatology, EEG findings, and imaging findings of the various forms of focal epilepsy. The majority of the article focuses on temporal and frontal lobe epilepsy as these represent the majority of focal epilepsies. RECENT FINDINGS: While significant overlap exists in the clinical symptomatology of the focal epilepsies, detailed seizure descriptions can often provide useful clinical evidence to help establish an accurate diagnosis. EEG and MRI continue to serve as the main diagnostic tools for the diagnosis of focal epilepsy. SUMMARY: The various forms of focal epilepsy generate seizure presentations that are dependent on the anatomic structures that are involved in the seizure. By understanding the symptoms typically generated in each region of the brain, a better understanding of the possible seizure localizations can be made. Most forms of epilepsy have clear changes on EEG that permit accurate localization, but several pitfalls exist, which are discussed in this article. Imaging has revolutionized our ability to accurately identify lesions associated with epilepsy and increased our ability to localize seizures in the brain.

Laser interstitial thermal therapy for medically intractable mesial temporal lobe epilepsy.

OBJECTIVE: To describe mesial temporal lobe ablated volumes, verbal memory, and surgical outcomes in patients with medically intractable mesial temporal lobe epilepsy (mTLE) treated with magnetic resonance imaging (MRI)-guided stereotactic laser interstitial thermal therapy (LiTT). METHODS: We prospectively tracked seizure outcome in 20 patients at Thomas Jefferson University Hospital with drug-resistant mTLE who underwent MRI-guided LiTT from December 2011 to December 2014. Surgical outcome was assessed at 6 months, 1 year, 2 years, and at the most recent visit. Volume-based analysis of ablated mesial temporal structures was conducted in 17 patients with mesial temporal sclerosis (MTS) and results were compared between the seizure-free and not seizure-free groups. RESULTS: Following LiTT, proportions of patients who were free of seizures impairing consciousness (including those with auras only) are as follows: 8 of 15 patients (53%, 95% confidence interval [CI] 30.1-75.2%) after 6 months, 4 of 11 patients (36.4%, 95% CI 14.9-64.8%) after 1 year, 3 of 5 patients (60%, 95% CI 22.9-88.4%) at 2-year follow-up. Median follow-up was 13.4 months after LiTT (range 1.3 months to 3.2 years). Seizure outcome after LiTT suggests an all or none response. Four patients had anterior temporal lobectomy (ATL) after LiTT; three are seizure-free. There were no differences in total ablated volume of the amygdalohippocampus complex or individual volumes of hippocampus, amygdala, entorhinal cortex, parahippocampal gyrus, and fusiform gyrus between seizure-free and non-seizure-free patients. Contextual verbal memory performance was preserved after LiTT, although decline in noncontextual memory task scores were noted. SIGNIFICANCE: We conclude that MRI-guided stereotactic LiTT is a safe alternative to ATL in patients with medically intractable mTLE. Individualized assessment is warranted to determine whether the reduced odds of seizure freedom are worth the reduction in risk, discomfort, and recovery time. Larger prospective studies are needed to confirm our preliminary findings, and to define optimal ablation volume and ideal structures for ablation.

Presurgery resting-state local graph-theory measures predict neurocognitive outcomes after brain surgery in temporal lobe epilepsy.

OBJECTIVE: This study determined the ability of resting-state functional connectivity (rsFC) graph-theory measures to predict neurocognitive status postsurgery in patients with temporal lobe epilepsy (TLE) who underwent anterior temporal lobectomy (ATL). METHODS: A presurgical resting-state functional magnetic resonance imaging (fMRI) condition was collected in 16 left and 16 right TLE patients who underwent ATL. In addition, patients received neuropsychological testing pre- and postsurgery in verbal and nonverbal episodic memory, language, working memory, and attention domains. Regarding the functional data, we investigated three graph-theory properties (local efficiency, distance, and participation), measuring segregation, integration and centrality, respectively. These measures were only computed in regions of functional relevance to the ictal pathology, or the cognitive domain. Linear regression analyses were computed to predict the change in each neurocognitive domain. RESULTS: Our analyses revealed that cognitive outcome was successfully predicted with at least 68% of the variance explained in each model, for both TLE groups. The only model not significantly predictive involved nonverbal episodic memory outcome in right TLE. Measures involving the healthy hippocampus were the most common among the predictors, suggesting that enhanced integration of this structure with the rest of the brain may improve cognitive outcomes. Regardless of TLE group, left inferior frontal regions were the best predictors of language outcome. Working memory outcome was predicted mostly by right-sided regions, in both groups. Overall, the results indicated our integration measure was the most predictive of neurocognitive outcome. In contrast, our segregation measure was the least predictive. SIGNIFICANCE: This study provides evidence that presurgery rsFC measures may help determine neurocognitive outcomes following ATL. The results have implications for refining our understanding of compensatory reorganization and predicting cognitive outcome after ATL. The results are encouraging with regard to the clinical relevance of using graph-theory measures in presurgical algorithms in the setting of TLE.