Anoxic-epileptic seizures: observational study of epileptic seizures induced by syncopes
Horrocks IA, Nechay A, Stephenson JBP, and Zuberi SM (2005) Anoxic-epileptic seizures: observational study of epileptic seizures induced by syncopes. Arch Dis Child 90:12 1283–7.
Abstract: AIMS: To describe a large series of children with anoxic-epileptic seizures (AES)--that is, epileptic seizures induced by syncopes. METHODS: Retrospective case-note review in a tertiary paediatric neurology unit. For all 27 children seen with a definite diagnosis of AES between 1972 and 2002, a review of clinical histories, videotapes, and EEG/ECG studies was undertaken. Main outcome measures were: age of onset, frequency and type of syncopes; age of onset and frequency of AES; type and duration of induced epileptic seizures; effect of treatment of syncopal and epileptic components. RESULTS: Median age of onset of syncopes was 8 months (range 0.2-120), frequency 2 in total to 40/day, median total approximately 200. Syncopes were predominantly reflex asystolic (RAS), prolonged expiratory apnoea (cyanotic breath-holding spells), or of mixed or uncertain origin; there was one each of ear piercing and hair grooming vasovagal syncope and one of compulsive Valsalva. Median age of onset of AES was 17 months (range 7-120), frequency from total 1 to 3/day, median total 3. The epileptic component was almost always bilateral clonic; three had additional epilepsy, one each with complex partial seizures, myoclonic absences, and febrile seizures plus. Median duration of epileptic component was 5 minutes (range 0.5-40, mean 11). Cardiac pacing prevented RAS in two patients: most other anti-syncope therapies were ineffective. Diazepam terminated the epileptic component in 6/8. Valproate or carbamazepine abolished AES in 5/7 without influencing syncope frequency. CONCLUSIONS: Although uncommon compared with simple syncopes, syncope triggered epileptic seizures (AES) are an important treatable basis of status epilepticus.
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- Retrospective case review over 30 year period. Defines anoxic-epileptic seizure as seizure induced by syncope. Seizures were usually bilateral clonic. In one case where a detailed time course is shown, EEG synchronization occurs about 12 s after syncope onset, but it is difficult to exclude the cause of the syncope (ocular compression in this case), rather than syncope itself, as a possible cause of the seizure. See () for discussion of hypoxia-induced termination of seizure.