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SUDEP in Seizure Monitoring Units: What Can Be Learned?

Summary and Comment |
October 22, 2013

SUDEP in Seizure Monitoring Units: What Can Be Learned?

  1. Robert C. Knowlton, MD, MSPH

A large international survey of seizure monitoring units reveals a consistent pattern of postictal cerebral activity suppression leading to cardiorespiratory dysfunction within a few minutes, culminating in terminal apnea followed by asystole.

  1. Robert C. Knowlton, MD, MSPH

Despite increased awareness, the mechanisms and risk factors involved in sudden unexplained death in epilepsy (SUDEP) remain enigmatic. As part of a larger study to better understand epilepsy-associated death, researchers assessed data from a large retrospective survey of 147 responding centers that provided detailed information on fatal cardiorespiratory arrests occurring during inpatient video-electroencephalogram (VEEG) monitoring.

SUDEP was involved in 16 of the 29 cardiorespiratory arrests captured in the census (constituting 1771 patient-years of monitoring). Half of the SUDEP cases were definite, and half were probable. All deaths were in adults. The remaining nine cardiorespiratory arrest cases were classified as near-SUDEP. In 10 cases of SUDEP, detailed cardiorespiratory and VEEG monitoring data were available. All 10 involved a similar pattern of postictal events in which generalized tonic–clonic seizure was followed by initial “neurovegetative breakdown” (tachypnea with variable heart rate, characterized mostly by bradycardia) along with diffuse cerebral activity suppression recorded on EEG, then gradually worsening cardiorespiratory function (including transient asystole) for a few minutes, leading to terminal apnea, and then asystole. The only slight deviation from this pattern was more-rapid evolution to terminal apnea in three cases. A similar pattern of initial postictal cardiorespiratory dysfunction and cerebral activity suppression was seen in the monitored near-SUDEP cases, and most SUDEP cases occurred at night during sleep. By contrast, most nonfatal near-SUDEP cases occurred during waking hours when detection and commencement of CPR was much faster. The authors strongly advise that seizure-monitoring units have improved supervision, in particular during nighttime hours.

Comment

Although the cause of the identified pattern of disturbances remains unclear, these findings more firmly point toward an association with the severe cerebral activity suppression that can occur following generalized tonic–clonic seizures. Nonetheless, a breakdown of neurovegetative function does not occur in most instances of postictal cerebral suppression. In epilepsy patients evaluated for surgery, secondarily generalized tonic–clonic seizures with marked diffuse suppression of cerebral activity are commonly captured because of medication withdrawal, yet cases of SUDEP and near-SUDEP are extremely rare. Increased supervision, especially at night, is certainly an appropriate recommendation. However, because the cost of 24-hour monitoring may result in lack of access to evaluation for curative epilepsy surgery, better recognition of the small subset of patients at high risk is needed such that selective special supervision may be instituted.

  • Disclosures for Robert C. Knowlton, MD, MSPH at time of publication Grant / research support NIH-NINDS Leadership positions in professional societies Southern Epilepsy and EEG Society (Treasurer)

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