Sudden Unexplained Death in Epilepsy
Sudden Unexplained Death in Epilepsy
abstract & commentary
Source: Kloster R, Engelskjon T. Sudden unexpected death in epilepsy (SUDEP): A clinical perspective and a search for risk factors. J Neurol Neurosurg Psychiatry 1999;67:439-444.
Sudden unexplained death in epilepsy (sudep) remains a leading risk among epileptics and accounts for between 0.35-5.9 deaths per year. Though some suspect that undetected seizures are the immediate cause of death, conclusive evidence, as well as consensus, is lacking. Ficker and associates (Ficker DM, et al. Neurology 1998;51:1270-1274) estimated from a population-based study that the risk of sudden unexpected death among young adult epileptics is 24 times higher than among healthy young adults. Prior studies, although typifying only small cohorts, have suggested several characteristic features of SUDEP victims. Most of these patients are male, and usually die at home—often in bed. Most also have histories of generalized tonic-clonic seizures, although the primary epilepsy may be focal or generalized. Seizures immediately preceding death are reported in a minority of patients. Antiepileptic drug levels determined post-mortem are usually subtherapeutic or undetectable.
Kloster and Engelskjon retrospectively analyzed a group of 140 epileptics who died over a 31-year period; 42 patients were classified as SUDEP and received post-mortem evaluation. Thirty-seven epileptics who died of identified causes also received post-mortem study. Causes of death in this latter group included status epilepticus, pneumonia, cardiac disease, trauma, suicide, and drowning.
Evaluation of historical and post-mortem pathological evaluation revealed the following points (see Table 1). No consistent difference in heart disease separated the two groups. Notably, however, pulmonary edema was present in almost two-thirds of SUDEP victims, more than twice the rate found in non-SUDEP victims. Brain edema was found in 19% of SUDEP victims, twice the rate of non-SUDEP victims. All SUDEP victims and nearly all non-SUDEP victims had experienced generalized motor convulsions resulting from either primary or secondary generalized seizures. Both also experienced frequent seizures. Signs of seizures immediately preceding death were reported for two-thirds of SUDEP patients. Insufficient data for the non-SUDEP group, however, precluded comparison. Circumstances of death were also revealing. Most SUDEP victims died in sleep at almost twice the rate expected if time of death occurred randomly. More than two-thirds of SUDEP victims were found prone at death, a small minority were supine, and the rest were in other positions. Post-mortem antiepileptic drug levels were tested in 23 SUDEP victims, and one or more anticonvulsants were found to be subtherapeutic in most. Ethanol levels were analyzed in 28 SUDEP victims, and were absent in all but one.
| Table 1-Comparison of Clinical and Post-mortem Factors in SUDEP and Non-SUDEP Patients | ||
| Variables | SUDEP | Non-SUDEP |
| Cerebral edema | 8/42 | 3/37 |
| Pulmonary edema | 26/42 | 10/37 |
| Evidence of seizure preceding death | 28/39 | 13/23 |
| Death occurred in sleep | 25/42 | |
| Position in sleep | 17/24 prone | |
| 1/24 supine | ||
| 6/24 other | ||
| Subtherapeutic anticonvulsant levels | 13/23 | 6 (N not reported) |
| Ethanol levels | 27/28 undetected | 0 |
| 1/28 low | (N not reported) | |
Commentary
Although retrospective findings are seldom conclusive, Kloster and Engelskjon provide data helpful to the practitioner. The immediate mechanisms responsible for SUDEP remain unknown, but most likely represent multiple pathologies. Ictal and postictal hypoventilation, respiratory insufficiency as a result of excess secretions or mechanical obstruction, and cardiac arrythmias—either as a result of seizures or as a primary event—may be implicated, but a single common pathology is lacking. Nevertheless, Kloster and Engelskjon disclose that at least two-thirds of SUDEP victims experienced seizures immediately preceding death, and at least one anticonvulsant level was found to be subtherapeutic in a majority of SUDEP victims. This finding suggests that patients with subtherapeutic anticonvulsant levels may be at increased risk for SUDEP. Also, the frequency of finding SUDEP victims in bed in the prone position bears further study. This position suggests that hypoventilation during or after a seizure may be lethal in the setting of mechanically restricted ventilation. Avoiding sleep positions of increased risk, or the availability of a relative to ensure the safe position of the patient may reduce the incidence of SUDEP. —fal
Which of the following statements is incorrect concerning sudden unexplained death in epilepsy (SUDEP)?
a. SUDEP most frequently occurs during sleep.
b. A majority of SUDEP victims are found in the prone position.
c. Pulmonary edema is usually present in SUDEP victims.
d. SUDEP victims are most likely to have at least one subtherapeutic anticonvulsant.
e. Seizures immediately precede death in 25% of SUDEP victims.
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