How Closely Should We Monitor for Nocturnal Seizures?

Commentary

Value of Video Monitoring for Nocturnal Seizure Detection in a Residential Setting.

van der Lende M, Cox FM, Visser GH, Sander JW, Thijs RD. Epilepsia 2016;57:1748–1753.

OBJECTIVE: Following a sudden death at a residential care unit, the Dutch Health and Care Inspectorate advised intensification of the use of video monitoring (VM) at the unit. We assessed whether VM resulted in increased identification of seizures that required clinical intervention. METHODS: The unit provides care for 340 individuals with refractory epilepsy and severe learning disabilities. Acoustic detection systems (ADSs) cover all individuals; 37 people also have a bed motion sensor (BMS) and 46 people with possible nocturnal seizures are now monitored by VM. During a 6-month period, in all cases of a suspected seizure we asked the caregivers to specify which device alerted them and to indicate whether this led to an intervention. Staff costs of VM were estimated using payroll information. RESULTS: We identified 1,208 seizures in 37 individuals: 4 had no nocturnal seizures and 393 (33%) seizures were seen only on video. In 169 (14%) of 1,208 seizures an intervention was made and this included 39 (10%) of 393 seizures seen only on video. When compared to seizures observed with an ADS or BMS, seizures seen only on video were more often tonic seizures (71% vs. 22%, p < 0.001) and occurred mostly in the beginning or at the end of the night (40% vs. 26%, p < 0.001). The extra staff costs of monitoring was 7,035 euro per seizure seen only on video and leading to an intervention. SIGNIFICANCE: VM facilitates nocturnal surveillance, but the costs are high. This underscores the need for development of reliable seizure detection devices.

When a patient is newly diagnosed with epilepsy, a question often arises: Will I (my child, parent, loved one, etc.) die from a seizure? This can be a challenging question to answer, and medical providers often search for methods to provide reassurance. Unfortunately, the standardized mortality ratio (SMR) in adults with epilepsy is 2.5 to 3.6 times that of the general population, and deaths due to seizures occur (1). Sudden unexpected death in epilepsy (SUDEP) is the most common cause of seizure-related death. Younger adults, age 20 to 40 years, with poorly-controlled epilepsy, neurologic deficit, and intellectual disability have been reported to be at highest risk for SUDEP (2). Other causes of seizure-related death include seizure-related accidents, status epilepticus, and aspiration during seizures (1). We currently do not have definitive ways to prevent SUDEP, because we do not fully understand the causative mechanisms and risk factors.

In a case-control study of SUDEP, 67% of those with unwitnessed death were found in bed. There were also 15 patients with witnessed deaths, and of these, 12 died in association with a witnessed generalized tonic-clonic seizure. Two of the other three were likely in a post-ictal state and one declared he/she was going to have a seizure, but then collapsed without having a convulsive seizure. Difficulty breathing was noted in 12 of the cases (3). Indeed, respiratory compromise is commonly reported in witnessed cases of SUDEP. SUDEP or near-SUDEP result from peri-ictal hypoxemia, central or obstructive hypoventilation/apnea, pulmonary edema, and ictal apnea. Most SUDEP patients are found prone in bed, and the decreased post-ictal arousal makes it likely they were unable to reposition themselves in bed. In 11 monitored cases of SUDEP, respiratory arrest always occurred before cardiac arrest. Nursing intervention before hypoxemia occurred significantly shortened the duration of peri-ictal hypoxemia and reduced the peak end-tidal CO₂ (4). Supervision at night was shown to be protective against seizure-related death (5).

Unfortunately, direct supervision throughout the night is not possible in most settings. Caregivers must also sleep. Therefore, the use of seizure-detection systems is increasing. However, not one of these commercially available devices is approved as a medical device, and seizure identification is far from perfect. In the recent article by van der Lende et al., additional video monitoring was implemented following a death due to SUDEP in a residential care facility for people with refractory epilepsy and intellectual disability. Video monitoring was used for those at higher risk for unwitnessed nocturnal convulsions. Acoustic detection system monitors were used on all patients, as well as bed motion sensors and video in a minority of patients. One person was responsible for monitoring up to 80 acoustic detection systems, 10 bed motion sensors, and 16 video feeds. To accommodate for the increase in residents undergoing video monitoring, four additional personnel were hired for the night shift. Seizures were classified, and degree of nursing intervention was scored.

Throughout the 6-month observation period, 1260 seizures were recorded in 37 people; of those, 393 seizures in 29 people were captured through video monitoring alone, and intervention was required in 39 of the seizures only seen on video in 14 people. Therefore, in a care facility of residents at risk for SUDEP (refractory epilepsy and severe learning disabilities), only 12% (41/340) underwent overnight video monitoring. In those, one-third of seizures were captured only through video. However, the vast majority (71%) of these were tonic seizures, not tonic-clonic seizures. Of all the seizures recorded, those detected through video alone and requiring intervention accounted for only 3% (39/1260).

How much did the additional video monitoring truly decrease the risk of SUDEP in these patients? The study determined that the cost of additional personnel (estimated €7035 per seizure recorded only on video and requiring intervention) outweighed the value of video monitoring. Loved ones of those who died from SUDEP may argue that this is a callous calculation, and that no cost is too high to prevent SUDEP. Can we provide some words of reassurance? Possibly.

First, it is important to remember that SUDEP, while tragic, is a relatively rare event. In a study combining the results of four population-based or community-based studies of children with epilepsy, possible SUDEP occurred in 33 per 100,000 person-years (PY). In those with uncomplicated epilepsy, this risk was even lower at 9 per 100,000 PY. By comparison, death due to other natural causes (pneumonia, ventriculoperitoneal shunt malfunction, etc.) occurred in 159 per 100,000 PY. Therefore, it was recommended that prevention of deaths, if possible, might be more related to good supportive care and infection control, rather than seizure management (6). In adults, the risk of SUDEP is certainly higher, with the incidence reported to be 121 per 100,000 PY in a population-based study. However, the overall mortality was 674 per 100,000 PY, again suggesting the majority of deaths in patients with epilepsy are not related to SUDEP (7).

Second, let us focus on the efficacy of the nonvideo monitoring systems in the study by van der Lende et al. Each staff is responsible for identifying seizures in up to 80 people, the majority only through an acoustic detection system. With this high patient-to-observer ratio, 67% of seizures were identified. Furthermore, the majority of tonic-clonic seizures, the seizures most associated with seizure-related death and injury, were detected without video monitoring, making the acoustic detection system quite effective in identifying convulsive seizures.

Just as there is no way to protect our loved ones from all . possible harm, there is no way to detect all seizures and prevent all complications thereof. However, in residential settings with much lower ratios of care providers to people with epilepsy, and with continued improvement in seizure detection devices, there is hope that reliable and cost-effective seizure identification is steadily becoming a reality.