Serotonin receptor expression in hippocampus and temporal cortex of temporal lobe epilepsy patients by postictal generalized electroencephalographic suppression duration

OBJECTIVE

Prolonged postictal generalized electroencephalographic suppression (PGES) is a potential biomarker for sudden unexpected death in epilepsy (SUDEP), which may be associated with dysfunctional autonomic responses and serotonin signaling. To better understand molecular mechanisms, PGES duration was correlated to 5HT1A and 5HT2A receptor protein expression and RNAseq from resected hippocampus and temporal cortex of temporal lobe epilepsy patients with seizures recorded in preoperative evaluation.

METHODS

Analyses included 36 cases (age = 14-64 years, age at epilepsy onset = 0-51 years, epilepsy duration = 2-53 years, PGES duration = 0-93 s), with 13 cases in all hippocampal analyses. 5HT1A and 5HT2A protein was evaluated by Western blot and histologically in hippocampus (n = 16) and temporal cortex (n = 9). We correlated PGES duration to our previous RNAseq dataset for serotonin receptor expression and signaling pathways, as well as weighted gene correlation network analysis (WGCNA) to identify correlated gene clusters.

RESULTS

In hippocampus, 5HT2A protein by Western blot positively correlated with PGES duration (p = .0024, R2  = .52), but 5HT1A did not (p = .87, R2  = .0020). In temporal cortex, 5HT1A and 5HT2A had lower expression and did not correlate with PGES duration. Histologically, PGES duration did not correlate with 5HT1A or 5HT2A expression in hippocampal CA4, dentate gyrus, or temporal cortex. RNAseq identified two serotonin receptors with expression that correlated with PGES duration in an exploratory analysis: HTR3B negatively correlated (p = .043, R2  = .26) and HTR4 positively correlated (p = .049, R2  = .25). WGCNA identified four modules correlated with PGES duration, including positive correlation with synaptic transcripts (p = .040, Pearson correlation r = .52), particularly potassium channels (KCNA4, KCNC4, KCNH1, KCNIP4, KCNJ3, KCNJ6, KCNK1). No modules were associated with serotonin receptor signaling.

SIGNIFICANCE

Higher hippocampal 5HT2A receptor protein and potassium channel transcripts may reflect underlying mechanisms contributing to or resulting from prolonged PGES. Future studies with larger cohorts should assess functional analyses and additional brain regions to elucidate mechanisms underlying PGES and SUDEP risk.

Sudden Unexpected Death in Epilepsy: Pathogenesis, Risk Factors, and Prevention

Sudden unexpected death in epilepsy (SUDEP) is a tragic and unexpected cause of death in patients with a known diagnosis of epilepsy. It occurs in up to 6.3 to 9.3/1,000 patients with drug-resistant epilepsy. The main three risk factors associated with SUDEP are the presence of generalized tonic-clonic seizures, the presence of a seizure in the past year, and an intellectual disability. There are several mechanisms that can result in SUDEP. The most likely sequence of events appears to be a convulsive seizure, overactivation of the autonomic nervous system, cardiorespiratory dysfunction, and death. While the risk of SUDEP is relatively high in patients with drug-resistant epilepsy, studies indicate that more than 50% of patients and caregivers are unaware of the diagnosis. Counseling about the diagnosis and preventative measures at the time of diagnosis is important. There are numerous interventions that may reduce the risk of SUDEP, including conservative measures such as nocturnal surveillance with a bed partner (where applicable) and automated devices. Optimizing seizure control with antiseizure medications and surgical interventions can result in a reduced risk of SUDEP.

Alternate Seizure Spread with Agenesis of the Corpus Callosum

Agenesis of the corpus callosum is a brain malformation that can occur in isolation or in conjunction with other congenital or developmental defects. The clinical sequelae of this condition include epilepsy, cognitive deficits, developmental delay, and various neurological and psychiatric disorders. Here we present the case of a patient with congenital complete agenesis of the corpus callosum and medically refractory epilepsy who underwent stereoelectroencephalography. This identified a left frontal ictal focus and revealed that contralateral spread occurred though the anterior commissure, a rare and interesting occurrence. Left frontal resection resulted in significant improvement. This demonstrates the role of the anterior commissure in ictal spread and the potential for novel methods of seizure spread in patients with temporal lobe epilepsy that must be considered in a surgical approach.

The role of convulsive seizures in SUDEP

Convulsive seizures are the most consistently reported risk factor for SUDEP. However, the precise mechanisms by which convulsive seizures trigger fatal cardiopulmonary changes are still unclear. Additionally, it is not clear why some seizures cause death when most do not. This article reviews the physiologic changes that occur during and after convulsive seizures and how these may contribute to SUDEP. Seizures activate specific cortical and subcortical regions that can cause potentially lethal cardiorespiratory changes. Clinical factors, including sleep state, medication treatment and withdrawal, positioning and posturing during seizures, and underlying structural or genetic conditions may also affect specific aspects of seizures that may contribute to SUDEP. While seizure control, either through medication or surgical treatment, is the primary intervention that reduces SUDEP risk, unfortunately, seizures cannot be fully controlled despite maximal treatment in a significant proportion of people with epilepsy. Thus specific interventions to prevent adverse seizure-related cardiopulmonary consequences are needed. The potential roles of repositioning/stimulation after seizures, oxygen supplementation, cardiopulmonary resuscitation and clinical treatment options in reducing SUDEP risk are explored. Ultimately, understanding of these factors may lead to interventions that could reduce or prevent SUDEP.

Improving prediction of sudden unexpected death in epilepsy: From SUDEP-7 to SUDEP-3

OBJECTIVE

Sudden unexpected death in epilepsy (SUDEP) is a significant cause of mortality in epilepsy. The aim of this study is to evaluate the validity of the SUDEP-7 inventory and its components as tools for predicting SUDEP risk, and to develop and validate an improved inventory.

METHODS

The study included 28 patients who underwent video-electroencephalography (EEG) monitoring and later died of SUDEP, and 56 age- and sex-matched control patients with epilepsy. The SUDEP-7 score, its individual components, and an alternative inventory were examined as predictors of SUDEP.

RESULTS

SUDEP-7 scores were significantly higher among SUDEP patients compared with controls, both at time of admission (p = 0.024) and most recent follow-up (p = 0.016). SUDEP-7 scores declined only among controls, who demonstrated reduced seizure frequency. Seizure freedom after epilepsy surgery was also associated with survival. Several components of the SUDEP-7 inventory were independently associated with higher risk of SUDEP, including more than three generalized tonic-clonic (GTC) seizures (p = 0.002), one or more GTC seizures (p = 0.001), or one or more seizures of any type within the last year (p = 0.013), and intellectual disability (p = 0.031). In stepwise regression models, SUDEP-7 scores did not enhance the prediction of SUDEP over either GTC seizure frequency or seizure frequency alone. A novel SUDEP-3 inventory comprising GTC seizure frequency, seizure frequency, and intellectual disability (p < 0.001) outperformed the SUDEP-7 inventory (p = 0.010) in predicting SUDEP.

SIGNIFICANCE

Our findings demonstrate the limitations of the SUDEP-7 inventory. We propose a new three-item SUDEP-3 inventory, which predicts SUDEP better than the SUDEP-7.

Automated Analysis of Risk Factors for Postictal Generalized EEG Suppression

Rationale: Currently, there is some ambiguity over the role of postictal generalized electro-encephalographic suppression (PGES) as a biomarker in sudden unexpected death in epilepsy (SUDEP). Visual analysis of PGES, known to be subjective, may account for this. In this study, we set out to perform an analysis of PGES presence and duration using a validated signal processing tool, specifically to examine the association between PGES and seizure features previously reported to be associated with visually analyzed PGES.

Methods: This is a prospective, multicenter epilepsy monitoring study of autonomic and breathing biomarkers of SUDEP in adult patients with intractable epilepsy. We studied videoelectroencephalogram (vEEG) recordings of generalized convulsive seizures (GCS) in a cohort of patients in whom respiratory and vEEG recording were carried out during the evaluation in the epilepsy monitoring unit. A validated automated EEG suppression detection tool was used to determine presence and duration of PGES.

Results: We studied 148 GCS in 87 patients. PGES occurred in 106/148 (71.6%) seizures in 70/87 (80.5%) of patients. PGES mean duration was 38.7 ± 23.7 (37; 1–169) seconds. Presence of tonic phase during GCS, including decerebration, decortication and hemi-decerebration, were 8.29 (CI 2.6–26.39, p = 0.0003), 7.17 (CI 1.29–39.76, p = 0.02), and 4.77 (CI 1.25–18.20, p = 0.02) times more likely to have PGES, respectively. In addition, presence of decerebration (p = 0.004) and decortication (p = 0.02), older age (p = 0.009), and hypoxemia duration (p = 0.03) were associated with longer PGES durations.

Conclusions: In this study, we confirmed observations made with visual analysis, that presence of tonic phase during GCS, longer hypoxemia, and older age are reliably associated with PGES. We found that of the different types of tonic phase posturing, decerebration has the strongest association with PGES, followed by decortication, followed by hemi-decerebration. This suggests that these factors are likely indicative of seizure severity and may or may not be associated with SUDEP. An automated signal processing tool enables objective metrics, and may resolve apparent ambiguities in the role of PGES in SUDEP and seizure severity studies.

Magnetic resonance-guided laser interstitial thermal therapy: Correlations with seizure outcome

OBJECTIVE

This study was undertaken to identify clinical factors associated with seizure freedom after magnetic resonance-guided laser interstitial thermal therapy (MRgLiTT) in temporal lobe epilepsy patients with unilateral mesial temporal sclerosis (MTS).

METHODS

We identified 56 patients with magnetic resonance imaging-defined MTS who underwent MRgLiTT with at least 1 year of follow-up. Primary outcome was seizure freedom at 1 year. We examined the association of seizure freedom and the following clinical factors: age at surgery, gender, history of febrile seizures, history of focal to bilateral tonic-clonic seizures, duration of epilepsy at the time of surgery, frequency of interictal epileptiform discharges (IEDs), seizure frequency, and presence of bilateral IEDs.

RESULTS

Thirty-five (62.5%) patients were seizure-free at 1 year. The presence of bilateral IEDs and age at surgery were associated with 1-year seizure freedom after MRgLiTT. The presence of bilateral IEDS was associated with lower odds of seizure freedom (odds ratio [OR] = .05, 95% confidence interval [CI] = .01-.46, p = .008), whereas increasing age at surgery was associated with increased odds of seizure freedom (OR = 1.10, 95% CI = 1.03-1.19, p = .009).

SIGNIFICANCE

This study demonstrates associations between presence of bilateral IEDs and age at surgery and seizure freedom at 1 year after MRgLiTT.

Seizure Clusters, Seizure Severity Markers, and SUDEP Risk

Rationale: Seizure clusters may be related to Sudden Unexpected Death in Epilepsy (SUDEP). Two or more generalized convulsive seizures (GCS) were captured during video electroencephalography in 7/11 (64%) patients with monitored SUDEP in the MORTEMUS study. It follows that seizure clusters may be associated with epilepsy severity and possibly with SUDEP risk. We aimed to determine if electroclinical seizure features worsen from seizure to seizure within a cluster and possible associations between GCS clusters, markers of seizure severity, and SUDEP risk. Methods: Patients were consecutive, prospectively consented participants with drug-resistant epilepsy from a multi-center study. Seizure clusters were defined as two or more GCS in a 24-h period during the recording of prolonged video-electroencephalography in the Epilepsy monitoring unit (EMU). We measured heart rate variability (HRV), pulse oximetry, plethysmography, postictal generalized electroencephalographic suppression (PGES), and electroencephalography (EEG) recovery duration. A linear mixed effects model was used to study the difference between the first and subsequent seizures, with a level of significance set at p < 0.05. Results: We identified 112 GCS clusters in 105 patients with 285 seizures. GCS lasted on average 48.7 ± 19 s (mean 49, range 2-137). PGES emerged in 184 (64.6%) seizures and postconvulsive central apnea (PCCA) was present in 38 (13.3%) seizures. Changes in seizure features from seizure to seizure such as seizure and convulsive phase durations appeared random. In grouped analysis, some seizure features underwent significant deterioration, whereas others improved. Clonic phase and postconvulsive central apnea (PCCA) were significantly shorter in the fourth seizure compared to the first. By contrast, duration of decerebrate posturing and ictal central apnea were longer. Four SUDEP cases in the cluster cohort were reported on follow-up. Conclusion: Seizure clusters show variable changes from seizure to seizure. Although clusters may reflect epilepsy severity, they alone may be unrelated to SUDEP risk. We suggest a stochastic nature to SUDEP occurrence, where seizure clusters may be more likely to contribute to SUDEP if an underlying progressive tendency toward SUDEP has matured toward a critical SUDEP threshold.

Association of Peri-ictal Brainstem Posturing With Seizure Severity and Breathing Compromise in Patients With Generalized Convulsive Seizures

OBJECTIVE

To analyze the association between peri-ictal brainstem posturing semiologies with postictal generalized electroencephalographic suppression (PGES) and breathing dysfunction in generalized convulsive seizures (GCS).

METHODS

In this prospective, multicenter analysis of GCS, ictal brainstem semiology was classified as (1) decerebration (bilateral symmetric tonic arm extension), (2) decortication (bilateral symmetric tonic arm flexion only), (3) hemi-decerebration (unilateral tonic arm extension with contralateral flexion) and (4) absence of ictal tonic phase. Postictal posturing was also assessed. Respiration was monitored with thoracoabdominal belts, video, and pulse oximetry.

RESULTS

Two hundred ninety-five seizures (180 patients) were analyzed. Ictal decerebration was observed in 122 of 295 (41.4%), decortication in 47 of 295 (15.9%), and hemi-decerebration in 28 of 295 (9.5%) seizures. Tonic phase was absent in 98 of 295 (33.2%) seizures. Postictal posturing occurred in 18 of 295 (6.1%) seizures. PGES risk increased with ictal decerebration (odds ratio [OR] 14.79, 95% confidence interval [CI] 6.18-35.39, p < 0.001), decortication (OR 11.26, 95% CI 2.96-42.93, p < 0.001), or hemi-decerebration (OR 48.56, 95% CI 6.07-388.78, p < 0.001). Ictal decerebration was associated with longer PGES (p = 0.011). Postictal posturing was associated with postconvulsive central apnea (PCCA) (p = 0.004), longer hypoxemia (p < 0.001), and Spo₂ recovery (p = 0.035).

CONCLUSIONS

Ictal brainstem semiology is associated with increased PGES risk. Ictal decerebration is associated with longer PGES. Postictal posturing is associated with a 6-fold increased risk of PCCA, longer hypoxemia, and Spo₂ recovery. Peri-ictal brainstem posturing may be a surrogate biomarker for GCS severity identifiable without in-hospital monitoring.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that peri-ictal brainstem posturing is associated with the GCS with more prolonged PGES and more severe breathing dysfunction.

Long-term video-EEG monitoring and interictal epileptiform abnormalities

In the appropriate clinical setting, the presence of interictal epileptiform abnormalities (IEAs) on EEG supports the diagnosis of epilepsy. However, the absence of epileptiform abnormalities on EEG cannot exclude a diagnosis of epilepsy. The goal of our study is to determine the prevalence of IEAs in patients with confirmed epilepsy, determined by having at least one epileptic seizure recorded during video-EEG monitoring. In addition, we aimed to analyze the time to recording IEAs and seizures in correlation with patient age, duration of epilepsy, and seizure focus localization. We retrospectively evaluate EEG data for all patients admitted to the epilepsy monitoring unit over a 2-year period. Of the 151 patients included, 129 (86%) patients had IEAs and 22 (14%) patients had no IEAs. Age and duration of epilepsy were not independent predictors of whether IEAs were present on EEG. The duration of EEG monitoring and time to first seizure did not influence IEA detection. In patients with IEAs, the mean time to the first IEA was 1.57 days. By day 5, IEAs were observed in 95% of the patients who had IEAs present on EEG (82% of total patients). The majority (75%) of patients also had their first seizure by day 5. We concluded that five days of EEG recording is optimal to detect IEAs and seizures, and that more prolonged recording has a low yield. Failure to detect IEAs should be interpreted with caution, and is not useful for diagnostic purposes.

Postictal serotonin levels are associated with peri-ictal apnea

OBJECTIVE

To determine the relationship between serum serotonin (5-HT) levels, ictal central apnea (ICA), and postconvulsive central apnea (PCCA) in epileptic seizures.

METHODS

We prospectively evaluated video EEG, plethysmography, capillary oxygen saturation (SpO₂), and ECG for 49 patients (49 seizures) enrolled in a multicenter study of sudden unexpected death in epilepsy (SUDEP). Postictal and interictal venous blood samples were collected after a clinical seizure for measurement of serum 5-HT levels. Seizures were classified according to the International League Against Epilepsy 2017 seizure classification. We analyzed seizures with and without ICA (n = 49) and generalized convulsive seizures (GCS) with and without PCCA (n = 27).

RESULTS

Postictal serum 5-HT levels were increased over interictal levels for seizures without ICA (p = 0.01), compared to seizures with ICA (p = 0.21). In patients with GCS without PCCA, serum 5-HT levels were increased postictally compared to interictal levels (p < 0.001), but not in patients with seizures with PCCA (p = 0.22). Postictal minus interictal 5-HT levels also differed between the 2 groups with and without PCCA (p = 0.03). Increased heart rate was accompanied by increased serum 5-HT levels (postictal minus interictal) after seizures without PCCA (p = 0.03) compared to those with PCCA (p = 0.42).

CONCLUSIONS

The data suggest that significant seizure-related increases in serum 5-HT levels are associated with a lower incidence of seizure-related breathing dysfunction, and may reflect physiologic changes that confer a protective effect against deleterious phenomena leading to SUDEP. These results need to be confirmed with a larger sample size study.

The association of serotonin reuptake inhibitors and benzodiazepines with ictal central apnea

OBJECTIVE

Ictal (ICA) and postconvulsive central apnea (PCCA) have been implicated in sudden unexpected death in epilepsy (SUDEP) pathomechanisms. Previous studies suggest that serotonin reuptake inhibitors (SRIs) and benzodiazepines (BZDs) may influence breathing. The aim of this study was to investigate if chronic use of these drugs alters central apnea occurrence in patients with epilepsy.

METHODS

Patients with epilepsy admitted to epilepsy monitoring units (EMUs) in nine centers participating in a SUDEP study were consented. Polygraphic physiological parameters were analyzed, including video-electroencephalography (VEEG), thoracoabdominal excursions, and pulse oximetry. Outpatient medication details were collected. Patients and seizures were divided into SRI, BZD, and control (no SRI or BZD) groups. Ictal central apnea and PCCA, hypoxemia, and electroclinical features were assessed for each group.

RESULTS

Four hundred and seventy-six seizures were analyzed (204 patients). The relative risk (RR) for ICA in the SRI group was half that of the control group (p = 0.02). In the BZD group, ICA duration was significantly shorter than in the control group (p = 0.02), as was postictal generalized EEG suppression (PGES) duration (p = 0.021). Both SRI and BZD groups were associated with smaller seizure-associated oxygen desaturation (p = 0.009; p ≪ 0.001). Neither presence nor duration of PCCA was significantly associated with SRI or BZD (p ≫ 0.05).

CONCLUSIONS

Seizures in patients taking SRIs have lower occurrence of ICA, and patients on chronic treatment with BZDs have shorter ICA and PGES durations. Preventing or shortening ICA duration by using SRIs and/or BZD in patients with epilepsy may play a possible role in SUDEP risk reduction.

Incidence, Recurrence, and Risk Factors for Peri-ictal Central Apnea and Sudden Unexpected Death in Epilepsy

Introduction: Peri-ictal breathing dysfunction was proposed as a potential mechanism for SUDEP. We examined the incidence and risk factors for both ictal (ICA) and post-convulsive central apnea (PCCA) and their relationship with potential seizure severity biomarkers (i. e., post-ictal generalized EEG suppression (PGES) and recurrence.

Methods: Prospective, multi-center seizure monitoring study of autonomic, and breathing biomarkers of SUDEP in adults with intractable epilepsy and monitored seizures. Video EEG, thoraco-abdominal excursions, capillary oxygen saturation, and electrocardiography were analyzed. A subgroup analysis determined the incidences of recurrent ICA and PCCA in patients with ≥2 recorded seizures. We excluded status epilepticus and obscured/unavailable video. Central apnea (absence of thoracic-abdominal breathing movements) was defined as ≥1 missed breath, and ≥5 s. ICA referred to apnea preceding or occurring along with non-convulsive seizures (NCS) or apnea before generalized convulsive seizures (GCS).

Results: We analyzed 558 seizures in 218 patients (130 female); 321 seizures were NCS and 237 were GCS. ICA occurred in 180/487 (36.9%) seizures in 83/192 (43.2%) patients, all with focal epilepsy. Sleep state was related to presence of ICA [RR 1.33, CI 95% (1.08–1.64), p = 0.008] whereas extratemporal epilepsy was related to lower incidence of ICA [RR 0.58, CI 95% (0.37–0.90), p = 0.015]. ICA recurred in 45/60 (75%) patients. PCCA occurred in 41/228 (18%) of GCS in 30/134 (22.4%) patients, regardless of epilepsy type. Female sex [RR 11.30, CI 95% (4.50–28.34), p < 0.001] and ICA duration [RR 1.14 CI 95% (1.05–1.25), p = 0.001] were related to PCCA presence, whereas absence of PGES was related to absence of PCCA [0.27, CI 95% (0.16–0.47), p < 0.001]. PCCA duration was longer in males [HR 1.84, CI 95% (1.06–3.19), p = 0.003]. In 9/17 (52.9%) patients, PCCA was recurrent.

Conclusion: ICA incidence is almost twice the incidence of PCCA and is only seen in focal epilepsies, as opposed to PCCA, suggesting different pathophysiologies. ICA is likely to be a recurrent semiological phenomenon of cortical seizure discharge, whereas PCCA may be a reflection of brainstem dysfunction after GCS. Prolonged ICA or PCCA may, respectively, contribute to SUDEP, as evidenced by two cases we report. Further prospective cohort studies are needed to validate these hypotheses.

Postconvulsive central apnea as a biomarker for sudden unexpected death in epilepsy (SUDEP)

OBJECTIVE

To characterize peri-ictal apnea and postictal asystole in generalized convulsive seizures (GCS) of intractable epilepsy.

METHODS

This was a prospective, multicenter epilepsy monitoring study of autonomic and breathing biomarkers of sudden unexpected death in epilepsy (SUDEP) in patients ≥18 years old with intractable epilepsy and monitored GCS. Video-EEG, thoracoabdominal excursions, nasal airflow, capillary oxygen saturation, and ECG were analyzed.

RESULTS

We studied 148 GCS in 87 patients. Nineteen patients had generalized epilepsy; 65 had focal epilepsy; 1 had both; and the epileptogenic zone was unknown in 2. Ictal central apnea (ICA) preceded GCS in 49 of 121 (40.4%) seizures in 23 patients, all with focal epilepsy. Postconvulsive central apnea (PCCA) occurred in 31 of 140 (22.1%) seizures in 22 patients, with generalized, focal, or unknown epileptogenic zones. In 2 patients, PCCA occurred concurrently with asystole (near-SUDEP), with an incidence rate of 10.2 per 1,000 patient-years. One patient with PCCA died of probable SUDEP during follow-up, suggesting a SUDEP incidence rate 5.1 per 1,000 patient-years. No cases of laryngospasm were detected. Rhythmic muscle artifact synchronous with breathing was present in 75 of 147 seizures and related to stertorous breathing (odds ratio 3.856, 95% confidence interval 1.395-10.663, p = 0.009).

CONCLUSIONS

PCCA occurred in both focal and generalized epilepsies, suggesting a different pathophysiology from ICA, which occurred only in focal epilepsy. PCCA was seen in 2 near-SUDEP cases and 1 probable SUDEP case, suggesting that this phenomenon may serve as a clinical biomarker of SUDEP. Larger studies are needed to validate this observation. Rhythmic postictal muscle artifact is suggestive of post-GCS breathing effort rather than a specific biomarker of laryngospasm.

Automated Detection of Postictal Generalized EEG Suppression

Although there is no strict consensus, some studies have reported that Postictal generalized EEG suppression (PGES) is a potential electroencephalographic (EEG) biomarker for risk of sudden unexpected death in epilepsy (SUDEP). PGES is an epoch of EEG inactivity after a seizure, and the detection of PGES in clinical data is extremely difficult due to artifacts from breathing, movement and muscle activity that can adversely affect the quality of the recorded EEG data. Even clinical experts visually interpreting the EEG will have diverse opinions on the start and end of PGES for a given patient. The development of an automated EEG suppression detection tool can assist clinical personnel in the review and annotation of seizure files, and can also provide a standard for quantifying PGES in large patient cohorts, possibly leading to further clarification of the role of PGES as a biomarker of SUDEP risk. In this paper, we develop an automated system that can detect the start and end of PGES using frequency domain features in combination with boosting classification algorithms. The average power for different frequency ranges of EEG signals are extracted from the prefiltered recorded signal using the fast fourier transform and are used as the feature set for the classification algorithm. The underlying classifiers for the boosting algorithm are linear classifiers using a logistic regression model. The tool is developed using 12 seizures annotated by an expert then tested and evaluated on another 20 seizures that were annotated by 11 experts.

Brainstem network disruption: A pathway to sudden unexplained death in epilepsy?

Observations in witnessed Sudden Unexpected Death in Epilepsy (SUDEP) suggest that a fatal breakdown of the central autonomic control could play a major role in SUDEP. A previous MR study found volume losses in the mesencephalon in focal epilepsy that were more severe and extended into the lower brainstem in two patients who later died of SUDEP. The aims of this study were to demonstrate an association (1) between brainstem volume loss and impaired autonomic control (reduced heart rate variability [HRV]); (2) between brainstem damage and time to SUDEP in patients who later died of SUDEP. Two populations were studied: (1) Autonomic system function population (ASF, 18 patients with focal epilepsy, 11 controls) with HRV measurements and standardized 3 T MR exams. (2) SUDEP population (26 SUDEP epilepsy patients) with clinical MRI 1-10 years before SUDEP. Deformation-based morphometry of the brainstem was used to generate profile similarity maps from the resulting Jacobian determinant maps that were further characterized by graph analysis to identify regions with excessive expansion indicating significant volume loss or atrophy. The total number of regions with excessive expansion in ASF was negatively correlated with HRV (r = -.37, p = .03), excessive volume loss in periaqueductal gray/medulla oblongata autonomic nuclei explained most of the HRV associated variation (r/r²  = -.82/.67, p < .001). The total number of regions with excessive expansion in SUDEP was negatively correlated with time to SUDEP (r = -.39, p = .03), excessive volume loss in the raphe/medulla oblongata at the obex level explained most of the variation of the time between MRI to SUDEP (r/r²  = -.60/.35,p = .001). Epilepsy is associated with brainstem atrophy that impairs autonomic control and can increase the risk for SUDEP if it expands into the mesencephalon.

Serum serotonin levels in patients with epileptic seizures

Profound cardiovascular and/or respiratory dysfunction is part of the terminal cascade in sudden unexpected death in epilepsy (SUDEP). Central control of ventilation is mediated by brainstem rhythm generators, which are influenced by a variety of inputs, many of which use the modulatory neurotransmitter serotonin to mediate important inputs for breathing. The aim of this study was to investigate epileptic seizure-induced changes in serum serotonin levels and whether there are potential implications for SUDEP. Forty-one epileptic patients were pooled into 2 groups based on seizure type as (1) generalized tonic-clonic seizures (GTCS) of genetic generalized epilepsy and focal to bilateral tonic-clonic seizures (FBTCS; n = 19) and (2) focal seizures (n = 26) based on clinical signs using surface video-electroencephalography. Postictal serotonin levels were statistically significantly higher after GTCS and FBTCS compared to interictal levels (P = .002) but not focal seizures (P = .941). The change in serotonin (postictal-interictal) was inversely associated with a shorter duration of tonic phase of generalized seizures. The interictal serotonin level was inversely associated with a shorter period of postictal generalized electroencephalographic suppression. These data suggest that peripheral serum serotonin levels may play a role in seizure features and earlier postseizure recovery; these findings merit further study.

The incidence and significance of periictal apnea in epileptic seizures

OBJECTIVE

The aim of this study was to investigate periictal central apnea as a seizure semiological feature, its localizing value, and possible relationship with sudden unexpected death in epilepsy (SUDEP) pathomechanisms.

METHODS

We prospectively studied polygraphic physiological responses, including inductance plethysmography, peripheral capillary oxygen saturation (SpO₂ ), electrocardiography, and video electroencephalography (VEEG) in 473 patients in a multicenter study of SUDEP. Seizures were classified according to the International League Against Epilepsy (ILAE) 2017 seizure classification based on the most prominent clinical signs during VEEG. The putative epileptogenic zone was defined based on clinical history, seizure semiology, neuroimaging, and EEG.

RESULTS

Complete datasets were available in 126 patients in 312 seizures. Ictal central apnea (ICA) occurred exclusively in focal epilepsy (51/109 patients [47%] and 103/312 seizures [36.5%]) (P < .001). ICA was the only clinical manifestation in 16/103 (16.5%) seizures, and preceded EEG seizure onset by 8 ± 4.9 s, in 56/103 (54.3%) seizures. ICA ≥60 s was associated with severe hypoxemia (SpO₂ <75%). Focal onset impaired awareness (FOIA) motor onset with automatisms and FOA nonmotor onset semiologies were associated with ICA presence (P < .001), ICA duration (P = .002), and moderate/severe hypoxemia (P = .04). Temporal lobe epilepsy was highly associated with ICA in comparison to extratemporal epilepsy (P = .001) and frontal lobe epilepsy (P = .001). Isolated postictal central apnea was not seen; in 3/103 seizures (3%), ICA persisted into the postictal period.

SIGNIFICANCE

ICA is a frequent, self-limiting semiological feature of focal epilepsy, often starting before surface EEG onset, and may be the only clinical manifestation of focal seizures. However, prolonged ICA (≥60 s) is associated with severe hypoxemia and may be a potential SUDEP biomarker. ICA is more frequently seen in temporal than extratemporal seizures, and in typical temporal seizure semiologies. ICA rarely persists after seizure end. ICA agnosia is typical, and thus it may remain unrecognized without polygraphic measurements that include breathing parameters.

Ictal coughing: Clinical features and differential diagnoses

PURPOSE

To describe a series of patients with ictal coughing to estimate its occurrence and characterize the clinical features and differential diagnoses.

METHODS

We retrospectively reviewed all the long-term video-EEG reports from Jefferson Comprehensive Epilepsy Center over a 7-year period (2010-2016) for the occurrence of the term "cough" in the text body. All the extracted reports were reviewed and patients with at least one documented ictal coughing at the epilepsy monitoring unit (EMU) were included in the study.

RESULTS

During the study period, 2487 patients were investigated at our EMU. Seven patients (0.28%) had at least one documented seizure accompanied by coughing. Four patients (0.16%) had epilepsy and three patients (0.12%) had psychogenic nonepileptic seizures (PNES). All patients with epilepsy had focal onset epilepsy; ictal coughing was not associated with any particular localization or lateralization.

CONCLUSION

We add to the literature on ictal coughing by providing additional information on its differential diagnosis and clinical features. Ictal coughing is a rare finding among patients evaluated at the EMUs. The differential diagnoses for ictal coughing include epilepsy and PNES. Epileptic ictal coughing is a rare semiological finding in patients with epilepsy and when present, it is invariably associated with focal epilepsy.

Equivocal significance of post-ictal generalized EEG suppression as a marker of SUDEP risk

PURPOSE

Our objective was to determine the significance of PGES as a possible EEG marker of increased risk for SUDEP and explore factors that influence PGES.

METHODS

We identified 17 patients who died due to definite or probable SUDEP and 52 living control patients with drug resistant focal epilepsy who underwent EEG monitoring and least one seizure recorded on EEG. We reviewed 305 seizures on EEG and when available, on video, for presence or absence of PGES, the duration of PGES immediately after seizure end, seizure type, state seizure occurred (sleep vs. wake), tonic duration and time from seizure onset to initial nursing intervention. We noted that majority (93% in SUDEP group and 83% living controls) with PGES had additional brief bursts of suppression. We measured the time from the end of seizure to end of last brief suppression to determine the time to final PGES.

RESULTS

SUDEP patients had statistically significant shorter PGES duration compared to living controls (unadjusted: -32.8s, 95%CI[-54.5, -11.2], adjusted: -39.5s, 95% CI[-59.4, -19.6]). SUDEP status was associated with longer time to final PGES compare to living controls, but this was not statistically significant. Earlier nursing intervention was associated with shorter seizure duration. PGES occurred only after GCS. Time to nursing intervention, tonic duration or state did not have a statistically significant effect on PGES.

CONCLUSIONS

PGES is an equivocal marker of increased SUDEP risk. Earlier nursing intervention is associated with shorter seizure duration and may play a role in reducing risk of SUDEP.

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.

Mesial temporal lobe epilepsy with childhood febrile seizure

OBJECTIVES

To evaluate the demographic and clinical manifestations of patients with mesial temporal sclerosis and temporal lobe epilepsy (MTS-TLE) with childhood febrile seizure (FS) and establishing the potential differences as compared to those without FS. We also investigated the surgery outcome in these two groups of patients.

MATERIALS AND METHODS

In this retrospective study, all patients with a clinical diagnosis of drug-resistant TLE due to mesial temporal sclerosis, who underwent epilepsy surgery at Jefferson Comprehensive Epilepsy Center, were recruited. Patients were prospectively registered in a database from 1986 through 2014. Postsurgical outcome was classified into two groups; seizure-free or relapsed. Clinical manifestations and outcome were compared between patients with MTS-TLE with FS and those without FS.

RESULTS

Two hundred and sixty-two patients were eligible for this study. One hundred and seventy patients (64.9%) did not have FS in their childhood, while 92 patients (35.1%) reported experiencing FS in their childhood. Demographic and clinical characteristics of these two groups of patients were not different. Postoperative seizure outcome was not statistically different between these two groups of patients (P = 0.19).

CONCLUSIONS

When MTS is the pathological substrate of TLE, clinical manifestations and response to surgical treatment of patients are very similar in patients with history of febrile seizure in their childhood compared to those without such an experience. In other words, when the subgroup of patients with MTS-TLE and drug-resistant seizures is examined history of childhood febrile seizure loses its value as a distinguishing factor in characteristics or predictive factor for surgery outcome.

Postsurgical outcome in patients with auditory auras and drug-resistant epilepsy

PURPOSE

We assessed whether patients with auditory auras have similar outcomes after epilepsy surgery as patients without auditory auras, and hypothesized that patients with non-dominant hemisphere foci might fare better after temporal lobe surgery than patients with dominant resections.

METHODS

In this retrospective study, outcome after temporal resection was assessed for patients with drug-resistant epilepsy. Preoperative demographic data, clinical data, and surgical outcome were prospectively registered in a database from 1986 through 2016. Seizure outcome was classified as either seizure-free or relapsed.

RESULTS

Data were available in 1186 patients. Forty five patients (3.8%) reported auditory auras; 42 patients (93%) had temporal lobe epilepsy (TLE), and three patients (7%) had extratemporal epilepsy. Since most patients with auditory auras had TLE and in order to have comparable groups, we selected 41 patients with auditory auras and compared them with patients without auditory auras who had temporal lobe resections (767 patients). There were no significant demographic or clinical differences between TLE patients with auditory auras and those without. Patients who had auditory auras were more likely to relapse after temporal lobe surgery than those without (p=0.03). Among patients who had auditory auras and temporal lobe surgery, side of surgery was not related to postoperative outcome (p=0.3).

CONCLUSION

Auditory auras are rare among patients with drug-resistant TLE. The presence of an auditory aura in a patient with drug-resistant TLE carries a worse prognosis for a postoperative seizure free outcome and this is not related to the side of surgery.

Post-epilepsy surgery psychogenic nonepileptic seizures

OBJECTIVES

We investigated the prevalence of post-epilepsy surgery psychogenic nonepileptic seizures (PNES) in patients with drug-resistant epilepsy and the possible influence of risk factors on these seizures.

METHODS

In this retrospective study, we examined data from all patients with a clinical diagnosis of drug-resistant epilepsy who underwent epilepsy surgery at Graduate Hospital and the Jefferson Comprehensive Epilepsy Center between 1986 and 2016. Postsurgical outcome was identified for up to 15 years after surgery. Diagnosis of PNES was verified in the epilepsy monitoring unit with video-electroencephalography (EEG) ictal recording. Potential associated factors were assessed by comparing patients with or without postoperative PNES.

RESULTS

A total of 1,105 patients were studied; 697 patients had postoperative seizures, and, of these, 27 patients (3.9%) had documented PNES after surgery. A full-scale intelligence quotient (IQ) <80 was significantly associated with post-epilepsy surgery PNES (odds ratio [OR] 2.89, p = 0.007, 95% confidence interval [CI] 1.33-6.29). A history of a preoperative psychiatric diagnosis was also significantly associated with post-epilepsy surgery PNES (OR 4.67, p = 0.0001, 95% CI 2.01-10.82). Other factors were not significantly associated with post-epilepsy surgery PNES.

SIGNIFICANCE

Post-epilepsy surgery PNES should be considered when patients report recurrent seizures after epilepsy surgery. Although these seizures probably occur relatively infrequently, attention to factors such as appearance of new ictal behaviors, a preoperative history of a psychiatric disorder, and a low full-scale IQ should raise suspicion and lead to appropriate diagnostic measures.

Seizure clusters in drug-resistant focal epilepsy

We investigated clinical factors associated with seizure clustering in patients with drug-resistant focal epilepsy and any association between seizure clustering and outcome after surgery. We performed a retrospective study including patients with a diagnosis of drug-resistant focal epilepsy who underwent epilepsy surgery. Patients were prospectively registered in a database from 1986 until 2015. Seizure cluster was defined as two or more seizures occurring within 2 days. Potential risk factors for seizure clustering were assessed. To investigate any potential association between seizure clusters and seizure outcome after surgery, time to event analysis was used to produce a Kaplan-Meier estimate of seizure recurrence. We studied 764 patients. Seizure clusters were reported in 23.6% of patients with temporal lobe epilepsy (TLE) and 16.9% of extratemporal patients (p = 0.2). We could not identify any significant clinical factors associated with seizure clustering. Among patients with TLE, those who had history of seizure clusters fared better after surgery (p < 0.01). We found that seizure clusters relate to prognosis after temporal lobe surgery in drug-resistant TLE. These data may provide added value for surgical prognostication when combined with other data types. A better understanding of the neurobiology underlying seizure clusters is needed.

Seasonality of birth in patients with temporal lobe epilepsy

OBJECTIVES

We investigated the seasonal pattern in births of patients with temporal lobe epilepsy and mesial temporal sclerosis. We hypothesized that the seasonal pattern in births of these patients is different from that in the general population.

MATERIALS AND METHODS

In this retrospective study, all patients who were evaluated for epilepsy surgery at Jefferson Comprehensive Epilepsy Center, Thomas Jefferson, Philadelphia, USA, between 1986 and 2014 and had a diagnosis of mesial temporal sclerosis (made by definite imaging findings of atrophy and/or sclerosis) were included. The seasonality in births of patients was compared with the seasonal pattern in the live births of the general population from Pennsylvania State.

RESULTS

Two hundred and eighty-two patients (146 females and 136 males) were studied. The seasonality pattern in birth of patients was not statistically different from that in the general population.

CONCLUSIONS

The observed contradictory findings among various studies indicate the need for further studies to elucidate whether season of birth brings the possibility of acquiring various epilepsy syndromes in the future. To investigate any possible association between season of birth and epilepsy, we suggest avoid pooling all patients with epilepsy together.

Nonseizure SUDEP: Sudden unexpected death in epilepsy without preceding epileptic seizures

OBJECTIVE

To describe the phenomenology of monitored sudden unexpected death in epilepsy (SUDEP) occurring in the interictal period where death occurs without a seizure preceding it.

METHODS

We report a case series of monitored definite and probable SUDEP where no electroclinical evidence of underlying seizures was found preceding death.

RESULTS

Three patients (two definite and one probable) had SUDEP. They had a typical high SUDEP risk profile with longstanding intractable epilepsy and frequent generalized tonic-clonic seizures (GTCS). All patients had varying patterns of respiratory and bradyarrhythmic cardiac dysfunction with profound electroencephalography (EEG) suppression. In two patients, patterns of cardiorespiratory failure were similar to those seen in some patients in the Mortality in Epilepsy Monitoring Units Study (MORTEMUS).

SIGNIFICANCE

SUDEP almost always occur postictally, after GTCS and less commonly after a partial seizure. Monitored SUDEP or near-SUDEP cases without a seizure have not yet been reported in literature. When nonmonitored SUDEP occurs in an ambulatory setting without an overt seizure, the absence of EEG information prevents the exclusion of a subtle seizure. These cases confirm the existence of nonseizure SUDEP; such deaths may not be prevented by seizure detection-based devices. SUDEP risk in patients with epilepsy may constitute a spectrum of susceptibility wherein some are relatively immune, death occurs in others with frequent GTCS with one episode of seizure ultimately proving fatal, while in others still, death may occur even in the absence of a seizure. We emphasize the heterogeneity of SUDEP phenomena.

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.

Patient Historical Risk Factors Associated with Seizure Outcome After Surgery for Drug-Resistant Nonlesional Temporal Lobe Epilepsy

OBJECTIVE

To investigate the possible influence of risk factors on seizure outcome after surgery for drug-resistant nonlesional temporal lobe epilepsy (TLE).

METHODS

This retrospective study recruited patients with drug-resistant nonlesional TLE who underwent epilepsy surgery at Jefferson Comprehensive Epilepsy Center and were followed for a minimum of 1 year. Patients had been prospectively registered in a database from 1991 to 2014. Postsurgical outcome was classified into 2 groups: seizure free or relapsed. The possible risk factors influencing long-term seizure outcome after surgery were investigated.

RESULTS

Ninety-five patients (42 males and 53 females) were studied. Fifty-four (56.8%) patients were seizure free. Only a history of febrile seizure in childhood affected the risk of postoperative seizure recurrence (odds ratio, 0.22; 95% confidence interval, 0.06-0.83; P = 0.02). Gender, race, family history of epilepsy, history of status epilepticus, duration of disease before surgery, aura symptoms, IQ, and seizure type or frequency were not predictors of outcome.

CONCLUSIONS

Many patients with drug-resistant nonlesional TLE responded favorably to surgery. The only factor predictive of seizure outcome after surgery was a history of febrile seizure in childhood. It is critical to distinguish among different types of TLE when assessing outcome after surgery.

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.

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.

Ketogenic diet in adolescents and adults with epilepsy

PURPOSE

The ketogenic diet is an alternative treatment for patients with refractory epilepsy. Most studies to date report dietary response in children. There are limited data evaluating the efficacy of the ketogenic diet in adults. This is a report of the long-term outcome in a largely adult population of patients treated with the ketogenic diet for epilepsy.

METHOD

Twenty-nine adult and adolescent patients (mean age 32 years, range 11-51) were initiated on the ketogenic diet and followed until diet discontinuation. Clinical response and adverse effects were noted during the duration of the diet.

RESULTS

Fifty-two percent of patients had a significant reduction in seizure frequency on the ketogenic diet, including 45% with ≥50% reduction in seizure frequency. Thirty-one percent had no improvement, seven percent were unable to successfully initiate the diet, and 10% had a >50% increase in seizure frequency. The diet was continued for a mean of 9 months (range 0.13-35 months), with five patients completing ≥23 months. There was a trend toward better response and better tolerability/longer duration in patients with symptomatic generalized epilepsy. The diet was generally well-tolerated, but undesired weight loss and constipation were the most frequent adverse effects.

CONCLUSION

The ketogenic diet can be used safely in the adult and adolescent population, with a response rate similar to those seen in children. Patient with symptomatic generalized epilepsy may be particularly good candidates for this type of dietary treatment.

Seizure recurrence and remission after switching antiepileptic drugs

PURPOSE

Studies of seizure outcome in patients undergoing serial antiepileptic drug trials have all been uncontrolled, with no account made for the spontaneous changes in disease state that could confound the elucidation of drug effects. In addition, no study has ever looked at outcome following antiepileptic drug switch in seizure-free patients, despite the fact that this is done routinely in clinical practice. We aimed to address both of these issues using a matched case-cohort design.

METHODS

We followed patients taking phenytoin or carbamazepine in monotherapy for focal epilepsy who were being crossed over to a newer agent as part of studies on the metabolic effects of anticonvulsant therapy. Many had been seizure-free but were being switched nonetheless due to side effects or concerns about long-term adverse consequences. Each patient was matched with two controls of the same seizure status who were taking anticonvulsant monotherapy and whose drug was not switched. Seizure freedom over the ensuing 6 months was the primary end point.

KEY FINDINGS

There were 43 cases and 86 matched controls. Twenty-three patients (cases) had been seizure-free on their old drug; 5 (21.7%) had seizure recurrence after drug switch compared to 2 (4.3%) of 46 matched controls. Twenty patients (cases) were having seizures on their old drug; 6 (30%) entered remission after drug switch, compared to 8 of 40 matched controls (20%). The two groups differed at baseline in number of anticonvulsants previously failed, which was the most important factor for prognosis. After statistical adjustment to account for this, seizure-free patients had 6.53 times higher odds of seizure recurrence if switched to a new drug (95% confidence interval [CI] 1.02-61.19; p = 0.06). Non-seizure-free patients had 1.66 times higher odds of remission if they remained on the same drug compared to switching, although this was not significant (95% CI 0.36-8.42; p = 0.532). Neither dose changes, nor drug mechanism, nor duration of seizure freedom had any bearing upon the results.

SIGNIFICANCE

Although the large majority of seizure-free patients remain so when switched to another agent, about one sixth have a recurrence attributable to the change. Conversely, our study design provides the first evidence to suggest that most improvements in drug-resistant patients are likely due to spontaneous remissions, not new drug introductions. These findings have conflicting implications for two competing models of comparative antiepileptic drug efficacy, which will require further study to elaborate.

Long-term cardiac rhythm and repolarization abnormalities in refractory focal and generalized epilepsy

This prospective study evaluated 19 individuals with refractory focal or generalized epilepsy utilizing an implantable cardiac loop recorder. Recording averaged 15 months (range 12-19 months) in 18 patients and 1.5 months in one patient. A median of 37 seizures per patient (range 3-657) occurred, with 1,477 seizures total. Cardiac arrhythmias and repolarization abnormalities occurred frequently (in 42% of patients) in refractory epilepsy, particularly during generalized tonic-clonic and tonic seizures. Patients with Lennox-Gastaut syndrome may be at high risk for cardiac abnormalities.

Surgical outcome in PET-positive, MRI-negative patients with temporal lobe epilepsy

PURPOSE

Fluorodeoxyglucose positron emission computed tomography (FDG-PET) hypometabolism is important for surgical planning in patients with temporal lobe epilepsy (TLE), but its significance remains unclear in patients who do not have evidence of mesial temporal sclerosis (MTS) on magnetic resonance imaging (MRI). We examined surgical outcomes in a group of PET-positive, MRI-negative patients and compared them with those of patients with MTS.

METHODS

We queried the Thomas Jefferson University Surgical Epilepsy Database for patients who underwent anterior temporal lobectomy (ATL) from 1991 to 2009 and who had unilateral temporal PET hypometabolism without an epileptogenic lesion on MRI (PET+/MRI-). We compared this group to the group of patients who underwent ATL and who had MTS on MRI. Patients with discordant ictal electroencephalography (EEG) were excluded. Surgical outcomes were compared using percentages of Engel class I outcomes at 2 and 5 years as well as Kaplan-Meier survival statistic, with time to seizure recurrence as survival time. A subgroup of PET+/MRI- patients who underwent surgical implantation prior to resection was compared to PET+/MRI- patients who went directly to resection without implantation.

KEY FINDINGS

  There were 46 PET+/MRI- patients (of whom 36 had 2-year surgical outcome available) and 147 MTS patients. There was no difference between the two groups with regard to history of febrile convulsions, generalized tonic-clonic seizures, interictal spikes, depression, or family history. Mean age at first seizure was higher in PET+/MRI- patients (19 ± 13 vs.14 ± 13 years, Mann-Whitney test, p = 0.008) and disease duration was shorter (14 ± 10 vs. 22 ± 13 years, student's t-test, p = 0.0006). Class I surgical outcomes did not differ significantly between the PET+/MRI- patients and the MTS group (2 and 5 year outcomes were 76% and 75% for the PET+/MRI- group, and 71% and 78% for the MTS group); neither did outcomes of the PET+/MRI- patients who were implanted prior to resection versus those who went directly to surgery (implanted patients had 71% and 67% class I outcomes at 2 and 5 years, whereas. nonimplanted patients had 77% and 78% class I outcomes, p = 0.66 and 0.28). Kaplan-Meier survival statistics for both comparisons were nonsignificant at 5 years. Dentate gyrus and hilar cell counts obtained from pathology for a sample of patients also did not differ between groups.

SIGNIFICANCE

PET-positive, MRI-negative TLE patients in our study had excellent surgical outcomes after ATL, very similar to those in patients with MTS, regardless of whether or not they undergo intracranial monitoring. These patients should be considered prime candidates for ATL, and intracranial monitoring is probably unnecessary in the absence of discordant data.

Employment after anterior temporal lobectomy

PURPOSE

To explore the effect of anterior temporal lobectomy on employment and define demographic and clinical predictors of postoperative employment in a large cohort with a prolonged observational period.

METHODS

Subjects had an anterior temporal lobectomy for refractory epilepsy. All had an assessment period of 4 years or more with documentation of demographic factors, employment status, and seizure frequency prospectively registered in a database at surgery and at each contact after surgery. McNemar chi-square and a Wilcoxon matched pairs test were used to compare employment status before and after surgery. A multiple logistic regression assessed independent predictors of postoperative employment status based on preoperative employment status.

KEY FINDINGS

Three hundred sixty-nine patients were evaluated. Employment levels were higher and unemployment levels were lower after surgery (McNemar χ(2) = 3.96; p = 0.047). Working before surgery (Wald's χ(2) = 22.69, p < 0.0001) and having a greater percent of seizure-free years (Wald's χ(2) = 34.43, p < 0.0001) were associated with being employed after surgery. Of 131 patients who were unemployed or homemakers before surgery, 67 (51.1%) became employed postoperatively, with a younger age at surgery, a younger age of epilepsy onset, and driving a motor vehicle associated with gaining employment. Of 172 patients who were working at baseline, 27 (15.7%) became unemployed or homemakers after surgery. Gender was the only variable associated with loss of employment, with women being more likely to become homemakers (χ(2) = 14.98, d.f.= 6, p = 0.02). Most students were working after surgery, with seizure control influencing outcome.

SIGNIFICANCE

Anterior temporal lobectomy is followed by reduced unemployment and underemployment, with elimination of seizures, relative youth, and operating a motor vehicle serving as the main driving forces for improvement. This is important information for patients and physicians who contemplate surgery as it helps define reasonable expectations, and provides further objective evidence for benefits beyond purely medical outcomes after epilepsy surgery.

Genetic drift and estimation of effective population size

The statistical properties of the standardized variance of gene frequency changes (a quantity equivalent to Wright's inbreeding coefficient) in a random mating population are studied, and new formulae for estimating the effective population size are developed. The accuracy of the formulae depends on the ratio of sample size to effective size, the number of generations involved (t), and the number of loci or alleles used. It is shown that the standardized variance approximately follows the chi(2) distribution unless t is very large, and the confidence interval of the estimate of effective size can be obtained by using this property. Application of the formulae to data from an isolated population of Dacus oleae has shown that the effective size of this population is about one tenth of the minimum census size, though there was a possibility that the procedure of sampling genes was improper.

Statistical Studies on Protein Polymorphism in Natural Populations. III. Distribution of Allele Frequencies and the Number of Alleles per Locus

With the aim of understanding the mechanism of maintenance of protein polymorphism, we have studied the properties of allele frequency distribution and the number of alleles per locus, using gene-frequency data from a wide range of organisms (mammals, birds, reptiles, amphibians, Drosophila and non-Drosophila invertebrates) in which 20 or more loci with at least 100 genes were sampled. The observed distribution of allele frequencies was U-shaped in all of the 138 populations (mostly species or subspecies) examined and generally agreed with the theoretical distribution expected under the mutation-drift hypothesis, though there was a significant excess of rare alleles (gene frequency, 0 approximately 0.05) in about a quarter of the populations. The agreement between the mutation-drift theory and observed data was quite satisfactory for the numbers of polymorphic (gene frequency, 0.05 approximately 0.95) and monomorphic (0.95 approximately 1.0) alleles.-The observed pattern of allele-frequency distribution was incompatible with the prediction from the overdominance hypothesis. The observed correlations of the numbers of rare alleles, polymorphic alleles and monomorphic alleles with heterozygosity were of the order of magnitude that was expected under the mutation-drift hypothesis. Our results did not support the view that intracistronic recombination is an important source of genetic variation. The total number of alleles per locus was positively correlated with molecular weight in most of the species examined, and the magnitude of the correlation was consistent with the theoretical prediction from mutation-drift hypothesis. The correlation between molecular weight and the number of alleles was generally higher than the correlation between molecular weight and heterozygosity, as expected.

Cardiac effects of seizures

Seizures frequently affect the heart rate and rhythm. In most cases, seizure-related cardiac changes are transient and do not appear to cause clinically significant abnormalities for the patient. Great interest in this area of research has been generated because of a possible connection with sudden unexpected death in epilepsy (SUDEP). While there are clear, but rare complications from seizure-related cardiac arrhythmias, such as ictal asystole that causes syncope, the overall risk of seizures on cardiac status and any potential connection between seizures and SUDEP still remain uncertain.