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Arrhythmias in the epilepsy monitoring unit: watching for sudden unexpected death in epilepsy.

ABSTRACT

Nurses who work with patients at risk for seizures should be informed that both adult and pediatric patients are at risk for sudden unexpected death in epilepsy (SUDEP). Although the exact pathophysiology of SUDEP is not determined, patients with mesial temporal lobe epilepsy represent an at-risk population because of autonomic dysregulation. With prompt treatment, patients with near-SUDEP can continue to lead normal productive lives. This case series presents three patients with near-SUDEP diagnosed with temporal lobe epilepsy.

Keywords: arrhythmias, epilepsy, seizures, sudden unexpected death in epilepsy (SUDEP)

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Sudden unexpected death in epilepsy (SUDEP) is a rare but significant risk for both adult and pediatric populations. SUDEP is defined as sudden, unexpected, nontraumatic, nondrowning death in an individual with epilepsy, witnessed or unwitnessed, in which postmortem examination does not reveal an anatomic or toxicologic cause for the death. Epidemiological studies suggest that about 2000 cases of SUDEP occur in the United States annually and that SUDEP accounts for 8%-17% of deaths in people with epilepsy. Although the cause is still unknown, hypotheses regarding multiple etiologie mechanisms involving dysregulation of the neurologic, cardiovascular, and pulmonary systems are being evaluated. Patients with mesial temporal lobe epilepsy (MTLE), one of the most common forms of epilepsy in adults, represent a specific patient population at risk for SUDEP (Opherk, Coromilas, & Hirsch, 2002). SUDEP occurs not only at home but also in the hospital setting, including in general medical-surgical units and the intensive care unit as well as in the epilepsy monitoring unit (EMU).

Background

Over a thousand adult or pediatric EMUs likely exist in the United States, with over 200 classified as specialized level 3 or 4 treatment centers as described by the National Association of Epilepsy Centers (2014). These units provide continuous video and electroencephalogram (EEG) monitoring of patient activity during a seizure event. For patients admitted to an EMU, the goals are to define and characterize the type of seizure (e.g., epileptic or psychogenic), to determine a need for medication adjustment, and to evaluate for epilepsy surgery (Labiner et al., 2010; Shafer et al., 2012). The EMU nursing staff typically receives special training in the recognition of subtle behavior and motor changes that may occur during a seizure, assisting in the video monitoring of the patient during a seizure, and administration of clinical trials (Labiner et al., 2010). EMU nurses also help to prevent preictal (before the seizure), intraictal (during a seizure), and postictal (after a seizure) complications.

One such complication is heart arrhythmias that can occur as a result of neurocardiac modulation. The American Clinical Neurophysiology Society in its published guidelines (http://www.acns.org/practice/ guidelines) recommends the use of at least a single-lead electrocardiogram (ECG) along with EEG (American Clinical Neurophysiology Society, 2013). Typically, an EEG technician is responsible for evaluating this rhythm strip in addition to the EEG. However, EEG technicians are not typically trained to recognize subtle changes that can occur on the ECG, which could be clinically relevant.

The inclusion of ECG telemetry monitoring that is monitored by a person trained to read ECG (e.g., a registered nurse) in patients with intractable seizures in an inpatient setting may provide early detection of lethal arrhythmias as well as other cardiac sequela of seizures and their treatments, such as various types of heart block. In addition, observing for changes in the cardiac rhythm may provide insight into the region of the brain that is involved in the seizure. Specifically, prior research in patients with MTLE lias shown that autonomic reflexes during the ictal phase of a seizure may evoke cardiac rhythm changes in 92% of patients (Koseoglu, Kucuk, Arman, & Ersoy, 2009).

The addition of ECG monitoring also provides nurses with the opportunity to evaluate worsening in a patient's condition by observing for changes in the ECG rhythm or heart rate (Espinosa, Lee, Tedrow, Bromfield, & Dworetzky, 2009). Although the most common arrhythmia seen in these patients is sinus tachycardia, at least 5%-10% of patients with temporal lobe seizures develop slowing of their heart rate, some to the level of bradycardia and even asystole (Koseoglu et al., 2009). These findings support the inclusion of continuous ECG monitoring as an adjunct to all epilepsy monitoring in general and temporal lobe epilepsy specifically.

This article will provide nurses with knowledge about patients with complex partial seizures originating in the temporal lobe and possible cardiac arrhythmias associated with these seizures (Opherk et al., 2002). To further understand the relationship between partial complex seizures and ictal asystole, we review three case studies of near-SUDEP.

Case Series

The first case is S. T. who is a 48-year-old woman who experienced frequent syncopal episodes while working a 12-hour shift as a registered nurse. Eight months earlier, she was diagnosed with idiopathic nocturnal seizures, which were successfully treated with phenytoin at bedtime. Because nocturnal seizures occur only during sleep (even during daytime naps), people may not follow full seizure safety recommendations, but they are still at risk for SUDEP. To fully assess her syncope, her heart rhythm was monitored for a 24-hour period using standard (Holter) cardiac monitoring.

S. T. chose to resume her normal routine while being monitored and returned to work as a staff nurse assigned to medical/surgical patient care for 12-hour shifts. While at work on her first full day of Holter monitoring, she was observed by her co-workers to be staring straight ahead, unresponsive, and having oral automatisms (i.e., chewing). In the emergency room, ECG monitoring revealed profound sinus bradycardia with a heart rate of 20 beats per minute. Review of the Holter monitor data revealed a preictal rhythm consisting of sinus tachycardia rapidly deteriorating to sinus bradycardia with a 19-second period of asystole during the event. She was transferred to a level 4 EMU for further monitoring by neurology and cardiology teams (Opherk et al., 2002).

Epilepsy monitoring recorded six complex partial seizures originating from the left temporal lobe. During each event, her cardiac rhythm evolved from normal sinus rhythm (preictal) to sinus tachycardia (intraictal) to bradycardia or asystole (intraictal and postictal). From a cardiac standpoint, she was diagnosed with cardiac tachy-brady syndrome, a malignant and potentially lethal arrhythmia associated with SUDEP (Schuele et al, 2007). Because of this condition, the cardiologists elected to implant a dual-chamber pacemaker (Wolber, Namdar, & Duru, 2010). She was discharged on a combination of phenytoin and valproic acid. Her seizures were unable to be controlled with medication, and thus, she elected to undergo a left temporal lobectomy, in which the mesial temporal structures (i.e., amygdala and hippocampus) are typically removed (Strzelczyk et al., 2011). Postsurgical follow-up and pacemaker analysis have noted rare pacemaker firing (the pacemaker's ventricular trigger rate was decreased to 40 bpm). S. T. has since returned to work lull time. She has had no seizures or auras postoperatively in addition to no more syncopal events.

Case 2 follows J. B., a 22-year-old college student with a 5-year history of complex partial seizures attributed to repeated mild traumatic brain injury (head impacts during full-contact football). Magnetic resonance imaging performed when he was 17 years old revealed an abnormal signal (i.e., scaring of the brain) consistent with bilateral mesial temporal sclerosis (Pinto et al., 2011). His typical seizure was consistent with complex partial seizures. Of note, the clinical semiology changed, and he was noted to have abrupt syncopal episodes at the time of seizure onset. He was admitted to a telemetry unit, where he had several 8-second periods of sinus arrest, which consistently happened as a seizure evolved. To further examine his cardiac rhythm, a loop recorder was implanted subcutaneously under his left chest wall (Pinto et al., 2011).

Over a 6-month period, J. B. had 18 sinus arrest events, each lasting from 6 to 8 seconds and coinciding with seizure activity. After a trial of several antiepileptic medications, he was referred to a level 4 EMU, where he had eight seizures that originated from the left and right temporal lobes independently. Although temporal lobe seizures are fairly well controlled with surgery, removal of both temporal lobes is associated with significantly higher morbidity (e.g., inability to form new memories after surgery but with preserved old memories) and is therefore not typically done (Harroud, Bouthillier, Weil, & Nguyen, 2012). Therefore, instead of a temporal lobectomy, he participated in a clinical trial for a new device referred to as responsive neurostimulation (RNS) (NeuroPace, Inc., Mountain View, CA), which had been recently approved by the Food and Drug Administration (Fitzgerald, 2014).

The RNS detects hypersynchronous activity (i.e., seizure) and, in response, shocks the region in an attempt to stop the progression of the seizure (i.e., desynchronize the brain; Heck et al., 2014). The overall functionality is analogous to a defibrillator for the heart. In addition to the RNS, J. B. remained on antiseizure medications. He returned to his neurologist's office every 2 weeks to interrogate and modulate the neurostimulator. He eventually became seizure free, and his antiseizure medications were tapered to monotherapy lacosamide. His implanted loop recorder showed no further sinus arrests for 6 months before it being removed. After 1 year of seizure freedom, he returned to college and is currently working on his Master's Degree in Business Administration.

Case 3 is a 29-year-old woman (A. R.) with a 14-year history of complex partial seizures that had been well controlled on lamotrigine monotherapy. After a job loss resulted in loss of insurance coverage, the cost of lamotrigine became prohibitive, and she was transitioned to phenytoin by an emergency room physician. Shortly after starting a new job, she had her typical seizure, which was characterized by motionless staring, lip movements (oral automatisms), and pill rolling of the left hand (unilateral manual automatisms) followed by syncope. She was taken to an emergency room, where she was noted to be postictal with a third-degree atrioventricular heart block. She was admitted to a level 4 EMU, and subsequent seizures were recorded and noted to be associated with similar cardiac changes.

As each seizure ended and A. R. began to regain consciousness, her cardiac rhythm would return to a normal sinus rhythm. Cardiology was consulted, and an echocardiogram was performed in the EMU. Higher levels of lamotrigine (she was eventually able to resume lamotrigine) controlled her seizures, so she was tapered off phenytoin and resumed her original cardiac mediations. She reports complete seizure control for the past 2 years and has since returned to work with no cardiac events and no further evidence of third-degree block with cardiology follow-up.

Discussion

Although there is no clear central unifying hypothesis for how and why SUDEP occurs in all cases, it appears that modulation of the autonomic nervous system plays a key role in at least some cases. The interplay between epileptic seizures and the autonomic nervous system is quite complex, but typically, changes occur when the seizure involves brain regions that regulate autonomic activity, including the limbic system and insular cortex. Symptoms can occur just before, during, or after a seizure has occurred. Thus, it is very important for nurses to have a better understanding of the autonomic manifestation of seizures, which includes apnea, nausea, incontinence, flushing of the skin, sweating, and/or cardiac arrhythmias. Although tachycardia is commonly seen, heart block, atrial fibrillation, bradycardia, and asystole also can be seen, which can lead to significant morbidity and mortality. If rhythm changes are present, cardiology consultation is recommended, and these patients may require implantation of a cardiac pacemaker and/or defibrillator. With mindful clinical observation by the nursing staff capable of incorporating ECG telemetry monitoring, inpatient SUDEP or near-SUDEP could be markedly reduced, perhaps even eliminated.

Conclusion

Nursing staff who care for patients with medically refractory epilepsy already protect their patients from known immediate injury. Although awareness of the risk for SUDEP is not widely known among nursing staff, it is required knowledge for nurses who care for patients with seizures. This is particularly true for patients with MTLE given its association with neuromodulation of cardiac rhythm. Knowledge of all possible complications of epileptic events can prevent some cases of SUDEP. Incorporating ECG telemetry monitoring in these patients may identify clinically relevant cardiac changes, including potentially lethal arrhythmias. Nurses, physicians, patients, and their families will rest easier knowing that every attempt to increase the safety and quality of life for that patient is being taken.

DOI: 10.1097/JNN.0000000000000139

References

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Elizabeth A. Dawson, BSN RN-BC PCCN, is a Staff Nurse, Kindred Hospital, Arlington, TX.

Puneet K. Gupta, MD MSE, is an Adjunct Assistant Professor, University of Texas Southwestern, Dallas, TX. He is also a Faculty Member at Neurology Consultants of Dallas, Dallas, TX; and a Faculty Member at Netra Health, LLC, McKinney, TX.

Christopher J. Madden, MD FAANS, is a Professor of Neurology, University of Texas Southwestern, Dallas, TX.

Joe Pacheco, PhD, is a Faculty Member, Netra Health, LLC, McKinney, TX.

Questions or comments about this article may be directed to DaiWai M. Olson, PhD RN CCRN, at DaiWai.Olson@utsouthwestern .edu. He is an Associate Professor, Division of Neurocritical Care, Departments of Neurology & Neurotherapeutics and Neurosurgery, UT Southwestern Medical Center, Dallas, TX.

The authors declare no conflicts of interest.
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Author:Dawson, Elizabeth A.; Gupta, Puneet K.; Madden, Christopher J.; Pacheco, Joe; Olson, DaiWai M.
Publication:Journal of Neuroscience Nursing
Article Type:Report
Date:Jun 1, 2015
Words:2685
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