Brief CommunicationOptimizing therapies for neurobehavioral comorbidities of epilepsy using chronic ambulatory electrocorticography
Introduction
There is an unmet need to improve therapy for various neuropsychiatric comorbidities and cognitive dysfunctions that have a high coincidence in persons with epilepsy (PWE) [1,2]. Anxiety, depression, psychosis, and impaired memory are some of the highly prevalent comorbidities in PWE [1,3,4]. Beyond seizure control, effective diagnosis, treatment, and monitoring of these comorbidities are critical as they impact the quality of life [5]. However, diagnosing these comorbidities remains challenging because a) seizures can masquerade as paroxysms of increased anxiety or panic attacks [6]; b) psychosis can be temporally related to increased epileptiform activities including seizure and postictal state [7]; and c) patient may fail to report symptoms due to seizure-related memory loss or social stigma. Additionally, PWE can report newer spells that are psychogenic nonepileptic seizures (PNES). The coexistence of PNES in PWE can pose a diagnostic challenge and can confound the treatment outcome [8]. Characterizing these events utilizing video-electroencephalography (vEEG) as the gold standard helps to discriminate these psychosomatic events from seizures. However, vEEG can be only performed for a limited amount of time (typically 3–5 days, max 1–2 weeks), and is often restricted to the inpatient setting, which limits access to this diagnostic tool. Chronic ambulatory electrocorticography (ECoG) from implanted Responsive Neurostimulator System (RNS®) can overcome these limitations by providing EEG that can be used to characterize and classify these psychosomatic paroxysms as a possible ictal, postictal, or interictal phenomenon and help with treatment decisions accordingly [9].
The RNS includes a cranially seated programmable neurostimulator that is connected to two leads, which are surgically placed over the suspected seizure onset zone [9]. From the two leads (4 channels), up to 12 min of electrocorticographic activity can be stored in the neurostimulator at any one time. Patients are provided with a customized telemetry unit (a wand that connects to a password-protected laptop) that can be used to download and archive the ECoG for any event of interest. Further, the patients can guide the storage of ECoG data by swiping a magnet of the neurostimulator itself whenever they have an event of concern. Here, we demonstrate the utility of the RNS in the management of psychiatric and neurological comorbidities in patients with drug-resistant focal epilepsy.
Section snippets
Methods
A single-center, retrospective study was conducted at a level IV epilepsy center. All patients with implanted RNS at the University of Alabama at Birmingham (UAB) epilepsy neuromodulation clinic were included in the study. Observations from patient visits and management, as documented in the electronic medical record, were reviewed. Since no additional appointments or treatment adjustments were based on this retrospective chart review, no formal consent was obtained as part of the study. The
Results
Among 21 patients with implanted RNS, there were five patients (23%) with significant neurobehavioral comorbidities whose presentation overlapped with their seizures and, hence, benefitted from the use of the ECoG data stored by the RNS. This group included 3 females and 2 males with 27–46 years of age. All patients were diagnosed with intractable multifocal epilepsy, and the epileptogenic cortex was not amenable to resection.
Discussion and conclusion
The five cases described above are great examples of the additional use of readily available ECoG data provided by the RNS in the management of comorbidities that are highly prevalent in PWE. The ability to access ECoG data and correlate them with patient magnet swipes during any paroxysmal event is unique compared with other therapeutic options in the field [9]. However, the RNS has its limitations. (1) The spatial sampling is restricted to only two four-contact cortical strip and/or depth
Declaration of competing interest
SP has served as a paid consultant for NeuroPace, Inc. but declares no targeted funding or compensation for this study. None of the authors share any competing interests.
Acknowledgment
SP and WM would like to thank NeuroPace representatives Ms. Kaitlyn Wilmer-Fierro and Mr. Mark Griffin and UAB study coordinator Ms. Kathleen Hernando.
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Cited by (11)
Applications of long-term data from neurostimulation devices
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2022, Clinical NeurophysiologyCitation Excerpt :The trend in LEC or interictal epileptiform activity (detections) may be used as valuable metrics to determine improvement in seizure control and may prompt the clinician to contact a patient to assess their overall well-being (Quraishi et al., 2020). RNS data can be used to rule out seizures in case of seizure mimickers such as panic attacks, psychogenic events, somatic symptom disorder, or acute postictal psychosis (Issa Roach et al., 2020). This is particularly of value during the COVID-19 pandemic, as elective admissions to characterize neurobehavioral spells are not always possible.
Closed-Loop Brain Stimulation and Paradigm Shifts in Epilepsy Surgery
2022, Neurologic ClinicsCitation Excerpt :Used in this manner, chronic iEEG monitoring can provide objective data with which to counsel patients regarding lifestyle choices in the areas of sleep hygiene, recreational drug use, and medication compliance. Similarly, the RNS system allows patients to trigger the storage of an iEEG record with use of a patient magnet that facilitates accurate characterization of patient-reported events, such as differentiating seizures from nonepileptic events, panic attacks, somatization disorders, and psychosis.60 Chronic iEEG recordings also are providing new opportunities to assess response to RNS therapy itself.
A journey into the unknown: An ethnographic examination of drug-resistant epilepsy treatment and management in the United States
2021, Epilepsy and BehaviorCitation Excerpt :It is still to be determined what factors influence this delay in time to surgery but may be multifactorial [51]. Like surgery, the use of neuromodulation in the therapeutic armamentarium is underutilized in the DRE population and was reflected in our field assessments [52,53] (Suppl. Fig. 5). Clarity about seizure burden reduction and associated side effects of each neuromodulation therapy was of particular concern for patients.
Effects of anterior thalamic nuclei stimulation on hippocampal activity: Chronic recording in a patient with drug-resistant focal epilepsy
2021, Epilepsy and Behavior ReportsCitation Excerpt :Another FDA-approved neurostimulation device for epilepsy, the RNS® System, operates with a closed-loop design [20] and is one of only two commercial devices that stores a limited form of chronic intracranial electroencephalography (cEEG) [21]. RNS cEEG has been used to address challenges in clinical epilepsy—seizure lateralization [22] and localization [23], spell characterization [24], evaluating anti-seizure medications (ASMs) [25], and seizure forecasting [26]—and it has also proven to be a powerful tool for basic neuroscience research on cortical language representation [27], spatial memory [28], and other cognitive functions [29,30]. RNS cEEG has helped characterize neural desynchronization related to vagus nerve stimulation [31] but, to our knowledge, it has not been used to quantify neurophysiological effects of an ANT DBS device implanted in the same individual.
Brain-responsive corticothalamic stimulation in the centromedian nucleus for the treatment of regional neocortical epilepsy
2020, Epilepsy and BehaviorCitation Excerpt :One clear distinction between responsive corticothalamic stimulation as delivered by the RNS System device as compared with available systems that deliver open-loop thalamic stimulation is that the RNS System also collects and stores chronic ambulatory iEEG and detection count data. These data have proven useful in measuring seizure burden [42], changes in antiepileptic medications [43,44], behavior modification [45], and characterizing neurobehavioral spells [46]. This was a retrospective chart review study at a single center.