Faculty Bibliography

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.

OBJECTIVE:To examine the consistency of applying the Nashef et al (2012) criteria to classify sudden unexpected death in epilepsy (SUDEP). METHODS:We reviewed cases from the North American SUDEP Registry (n = 250) and Medical Examiner Offices (n = 1301: 698 Maryland, 457 New York City, 146 San Diego). Two epileptologists with expertise in SUDEP and epilepsy-related mortality independently reviewed medical records, scene investigation, autopsy, and toxicology and assigned a SUDEP class. RESULTS:Major areas of disagreement arose between adjudicators concerned differentiating (1) Definite SUDEP Plus Comorbidity from Possible SUDEP and (2) Resuscitated (Near) SUDEP from SUDEP. In many cases, distinguishing between contributing and competing causes of death when trying to classify Definite SUDEP Plus Comorbidity versus Possible SUDEP is ambiguous and relies on judgement. Similarly, determining if an intervention was lifesaving or not (Resuscitated SUDEP or Not SUDEP), or if resuscitation merely delayed SUDEP (Resuscitated SUDEP or SUDEP) is often a judgement call and can differ between experienced adjudicators. Given these persisting ambiguities, we propose more explicit criteria for distinguishing these categories. SIGNIFICANCE/CONCLUSIONS:Accurate and consistent classification of cause of death among individuals with epilepsy remains a dire public health concern. SUDEP is likely underestimated in national health statistics. Greater standardization of criteria among epilepsy researchers, medical examiners, and epidemiologists to determine cause and classify death will lead to more accurate tracking of SUDEP and other epilepsy-related mortalities.

BACKGROUND AND PURPOSE/OBJECTIVE:Epilepsy is a chronic neurological disease that represents a tremendous burden on both patients and society in general. Studies have addressed how demographic variables, socioeconomic variables, and psychological comorbidity are related to the quality of life (QOL) of people with epilepsy (PWE). However, there has been less focus on how these factors may differ between patients who exhibit varying degrees of seizure control. This study utilized data from the Managing Epilepsy Well (MEW) Network of the Centers for Disease Control and Prevention with the aim of elucidating differences in demographic variables, depression, and QOL between adult PWE. METHODS:Demographic variables, depression, and QOL were compared between PWE who experience clinically relevant differences in seizure occurrence. RESULTS:Gender, ethnicity, race, education, income, and relationship status did not differ significantly between the seizure-frequency categories (p>0.05). People with worse seizure control were significantly younger (p=0.039), more depressed (as assessed using the Patient Health Questionnaire) (p=0.036), and had lower QOL (as determined using the 10-item Quality of Life in Epilepsy for Adults scale) (p<0.001). CONCLUSIONS:The present results underscore the importance of early screening, detection, and treatment of depression, since these factors relate to both seizure occurrence and QOL in PWE.

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/CONCLUSIONS: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.

OBJECTIVE:To study the incidence and clinical features of sudden unexpected death in epilepsy (SUDEP) in patients treated with direct brain-responsive stimulation with the RNS System. METHODS:All deaths in patients treated in clinical trials (N = 256) or following U.S. Food and Drug Administration (FDA) approval (N = 451) through May 5, 2016, were adjudicated for SUDEP. RESULTS:There were 14 deaths among 707 patients (2208 postimplantation years), including 2 possible, 1 probable, and 4 definite SUDEP events. The rate of probable or definite SUDEP was 2.0/1000 (95% confidence interval [CI] 0.7-5.2) over 2036 patient stimulation years and 2.3/1000 (95% CI 0.9-5.4) over 2208 patient implant years. Stored electrocorticograms around the time of death were available for 4 patients with probable/definite SUDEP and revealed the following: frequent epileptiform activity ending abruptly (n = 2), no epileptiform activity or seizures (n = 1), and an electrographic and witnessed seizure with cessation of postictal electrocorticography (ECoG) activity associated with apnea and pulselessness (n = 1). SIGNIFICANCE/CONCLUSIONS:The SUDEP rate of 2.0/1000 patient stimulation years among patients treated with the RNS System is favorable relative to treatment-resistant epilepsy patients randomized to the placebo arm of add-on drug studies or with seizures after resective surgery. Our findings support that treatments that reduce seizures reduce SUDEP risk and that not all SUDEPs follow seizures.