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Safety in epilepsy monitoring units

[Part 3: Challenges; Rheims S & Ryvlin P]



Long-term video-EEG monitoring (LTM) is an essential and necessary diagnostic tool to investigate patients with uncontrolled seizures. Clinical indications  for LTM as well as the essential services, personnel and facilities have been detailed in guidelines released by several learned societies, including the International League against Epilepsy, the American Clinical Neurophysiology Society and the National Association of Epilepsy Centers (NAEC) (American Clinical Neurophysiology Society, 2008; Velis et al., 2007; The NAEC, 2010), with a specific emphasis on the equipment and technical procedures required to effectively capture seizures. In contrast, procedures needed to ensure patients’ safety during LTM were much less thoroughly evaluated. However, management of safety issues during LTM has progressively emerged as one of the key elements that should be taken into account  in epilepsy monitoring unit (EMU) organization.


Overall, severe adverse events affect more than 10% of patients who undergo LTM (Rheims & Ryvlin, 2014). These severe adverse events primarily include status epilepticus, seizure-related injuries and psychiatric complications. Although rare, cardiac events and/or respiratory complications have also been reported during LTM. One study reported serious peri-ictal cardiac abnormality in three out of 109 patients (2.75%), including one ictal asystole that was subsequently treated with a cardiac pacemaker, one brief ventricular tachycardia that resolved spontaneously, and one acute ST-segment depression that rapidly resolved without specific intervention (Noe & Drazkowski, 2009). Respiratory complications might also occur, related either to the risk of aspiration during and/or immediately after seizure or to the risk of respiratory failure directly related to ictal activity, about one third of seizures being associated with oxygen desaturation < 90%, and about 10% with oxygen desaturation < 80% (Bateman et al., 2008). Finally, seizures in EMUs can lead to cardiorespiratory arrest and death, including Sudden Unexpected Death in Epilepsy (SUDEP). The international MORTEMUS study aimed at quantifying this risk over all EMUs identified in Europe, Israel, Australia and New Zealand (Ryvlin et al., 2013). This study showed that the incidence of SUDEP in adults in EMUs was 5.1 per 1000 patient-years (95% CI 2·6–9·2) (Ryvlin et al., 2013), a figure comparable to that observed in similar population out of hospital (on average 4/1000 patient-years) (Tomson et al., 208). Although rare, SUDEP and near-SUDEP were encountered by more than 10% of all EMUs surveyed in MORTEMUS. A recent survey of 70 US-based units showed that 7% of centres have encountered a cardiac arrest, and 3% a death, within the past 12 months (Shafer et al., 2011).


Although the risk factors of adverse events in the epilepsy monitoring unit remain to be formally determined, two aspects might be of primary importance: (1) management of antiepileptic drugs (AED) withdrawal, and (2) patients’ supervision during LTM.


1) AEDs are often reduced during LTM to promote the occurrence of seizures and shorten its duration. While facilitating the admission of more patients, this procedure might also increase exposure to significant risks, including generalized tonic-clonic seizure in patients not usually presenting this seizure type, seizure clusters or status epilepticus. Which proportion of severe adverse events is promoted by AEDs withdrawal is not precisely known but is likely to be very high, according to the observation that seizure-related injuries are much more frequent in EMUs than out of hospital (Dobesberger et al., 2011; Sanders et al., 1996; Neufeld et al., 1999).  Furthermore, all observed SUDEP cases collected in MORTEMUS occurred following a generalized tonic-clonic seizure, most often in patients with >50% to 100% antiepileptic drugs withdrawal (Ryvlin et al. 2013). Many of these patients did not suffer a generalized tonic-clonic seizure in the last three months (some never had a generalized tonic-clonic seizure), strongly suggesting that AED withdrawal was directly responsible for the occurrence of a fatal generalized tonic-clonic seizure (Ryvlin et al., 2013). Importantly, this potential causality is supported by the complementary observation that addition of another antiepileptic drug during randomised controlled trials of refractory epilepsy was found to decrease by seven fold the risk of SUDEP compared with placebo (Ryvlin et al., 2011). Most EMUs which reported safety data did not use a standardized protocol of AED withdrawal, and rather tapered AEDs on a case-by-case basis (Rheims & Ryvlin 2014). It has been suggested that standardized protocol of AEDs withdrawal might reduce the risk of adverse events during LTM (Di Gennaro et al., 2012; Rose et al., 2003). However, no such protocol has yet been recommended (The NAEC 2013) and whether or not the modalities of AEDs tapering (i.e. more or less rapid or marked) impact the risk of seizures clusters and status epilepticus remains to formally be established. Nevertheless, the NAEC recommends that medication reduction should be avoided in the outpatient setting prior to LTM and that a specific protocol should be available within EMUs.


2) One of the strongest recommendations of the NAEC is the requirement of continuous observation (24/24) by trained staff (The NAEC, 2010). Thus, continuous observation should be performed by EEG technologist or epilepsy nurses. Furthermore, a formal educational program should be developed in each center to ensure appropriate safety expertise (NAEC, 2010). However, the AES survey reported that 26% of EMUs did not benefit from such permanent supervision and that the level of knowledge about safety issues in EMU was low (Buelow et al., 2009). Similarly, 20% of responding European EMUs reported intermittent or only daytime supervision (Rubbloi et al., 2013). It might be speculated that the rate of adverse events might be greater in EMUs not benefiting from continuous supervision. As a matter of fact, more than half of SUDEP and near fatal SUDEP cases reported in the MORTEMUS study occurred under a similar level of supervision to that of a standard neurological ward where the patient’s clinical status is checked a few times per night.


The issue of patients’ safety during LTM has long been neglected. Although the situation has recently improved, prevention of adverse events remains non-optimized in a significant number of EMUs and many issues remain to be addressed. Published data support implementation of new safety protocols and harmonization of EMU organization and management of LTM, but the impact of these procedures on patients’ safety require prospective multicentric evaluation.



Sylvain Rheims, Department of Functional Neurology and Epileptology and Institute for Epilepsies (IDEE), France

Philippe Ryvlin, Department of Functional Neurology and Epileptology and Institute for Epilepsies (IDEE), France

Dec 2014



How to cite:

Rheims S & Ryvlin P. Safety in epilepsy monitoring units. In: Hanna J, Panelli R, Jeffs T, Chapman D, editors. Continuing the global conversation [online]. SUDEP Action, SUDEP Aware & Epilepsy Australia; 2014 [retrieved day/month/year]. Available from:































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Ryvlin P, Cucherat M, Rheims S. Risk of sudden unexpected death in epilepsy in patients given adjunctive antiepileptic treatment for refractory seizures: a meta-analysis of placebo-controlled randomised trials. Lancet Neurol 2011;10:961-68.

Ryvlin P, Nashef L, Lhatoo SD, Bateman LM, Bird J, Bleasel A, Boon P, Crespel A, Dworetzky BA, Høgenhaven H, Lerche H, Maillard L, Malter MP, Marchal C, Murthy JM, Nitsche M, Pataraia E, Rabben T, Rheims S, Sadzot B, Schulze-Bonhage A, Seyal M, So EL, Spitz M, Szucs A, Tan M, Tao JX, Tomson T. Incidence and mechanisms of cardiorespiratory arrests in epilepsy monitoring units (MORTEMUS): a retrospective study. Lancet Neurol 2013;12(10):966-77.

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Shafer PO, Buelow J, Ficker DM, Pugh MJ, Kanner AM, Dean P, et al. Risk of adverse events on epilepsy monitoring units: a survey of epilepsy professionals. Epilepsy Behav 2011;20(3):502-05.

Tomson T, Nashef L, Ryvlin P. Sudden unexpected death in epilepsy: current knowledge and future directions. Lancet Neurol 2008;7(11):1021–31.

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continuing the global conversation

Sudden Unexpected Death in Epilepsy
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