In the past few decades, sudden death has been emphasized as an underappreciated problem in the epileptic population. Certainly, the mortality in individuals with epilepsy is increased ostensibly from accidents, suicide, and the underlying cause of seizures. However, the main contributor to the increased mortality rate in otherwise healthy people with epilepsy is unexpected death outside of circumstances such as drowning, trauma from a fall, myocardial infarction, and automobile accidents during the seizure. It is to this group that the acronym “SUDEP,” or sudden unexplained death in epilepsy, has been applied. Surprisingly, unexpected death is predominantly an issue of adulthood more than of childhood. The rate of unexpected death increases with the duration and severity of epilepsy and several population studies suggest that the rate may be as high as several-fold higher than in age matched individuals in the general population. The rate of this entity is generally given as approximately 0.35 cases per 1,000 person years but with severe epilepsy, and as high as 3 to 9 per 1,000 person years, as summarized by Leestma and colleagues. Most patients affected have a history of generalized tonic-clonic seizures and die in bed. In children, those with treatment resistant epilepsy, developmental delay and several syndromes such as tuberous sclerosis are at particular risk.
Several factors have emerged as risks from population-based and cohort case controlled studies; the postictal period immediately after a tonic clonic seizure, increasing seizure frequency (including three generalized seizures in the preceding year), lack of successful treatment (i.e., patients not in remission as documented in a 40-year follow-up of childhood epilepsy by Sillanpää and Shinnar), or subtherapeutic levels of antiepileptic drugs, the period of early adulthood, long-standing epilepsy, and mental retardation.
Most instances of SUDEP occur when the patient is unattended or during sleep. Although respiratory difficulty and cardiac changes including asystole and ventricular arrhythmias are known to occur during and immediately after seizures, none of these has been a consistent factor and usually, the precise mechanism of death has been difficult to determine. A postictal “shutdown” of brainstem activity resulting in hypercapnia or hypoxemia has been suggested but there may be various causes operative in different cases.
One approach to preventing sudden death is adequate treatment with antiepileptic drugs. The risk of sudden death is as high as 20 times greater for untreated patients. Some specialists in the field of epilepsy have suggested that an open conversation be undertaken about the problem with patients and their families. More often, neurologists raise the issue only in high risk patients or when specifically asked. A review of this subject has been provided by Devinsky.
There remain to be considered several epileptic syndromes and other seizure states that cannot be readily classified with the usual types of generalized or partial seizures. Many of these, particularly the first four entities discussed below, have been found to have a genetic basis, typically involving an ion channel disorder.
Benign Epilepsy of Childhood With Centrotemporal Spikes (Rolandic Epilepsy, Sylvian Epilepsy)
This common focal motor epilepsy is unique among the focal epilepsies of childhood in that it is self-limiting despite a very abnormal EEG pattern. It is usually transmitted in families as an autosomal dominant trait and begins between 5 and 9 years of age. It typically announces itself by a nocturnal tonic-clonic seizure with focal onset. Thereafter, the seizures take the form of clonic contractions of one side of the face, less often of one arm or leg, and the interictal EEG shows high-voltage spikes in the contralateral lower rolandic or centrotemporal area.
Seizures are readily controlled by a single anticonvulsant drug and gradually disappear during adolescence. The relation of this syndrome to developmental dyslexia is unsettled.
Epilepsy with Occipital Spikes (Panayiotopoulos Syndrome)