Seizures
More than 90% of individuals with AS are reported to have seizures but this may be an overestimate because medical reports tend to dwell on the more severe cases. Less than 25% develop seizures before 12 months of age. Most have onset before 3 years, but occurrence in older children or in teenagers is not exceptional. The seizures can be of any type (i.e. major motor involving jerking of all extremities; absence type involving brief periods of lack of awareness), and may require multiple anticonvulsant medications. Seizures may be difficult to recognize or distinguish from the child’s usual tremulousness, hyperkinetic limb movements or attention deficits. The typical EEG is often more abnormal than expected from the clinical appearance, and it may suggest seizures when in fact there are none[1-3].
There is no agreement as to the optimal seizure medication although valproic acid (Depakote), topiramate (Topamax), lamotrigine (Lamictal), levetiracetam (Keppra), and clonazepam (Klonopin) are more commonly used in the North Amereica. Carbamazepine (Tegretol), ethosuximide (Zarontin), phenytoin (Dilantin), phenobarbital, and ACTH are less commonly used. Vigabatrin (Sabril), an inhibitor of GABA metabolism, should not be used. [4] Single medication use is preferred but seizure breakthrough is common. Some children with uncontrollable seizures have been placed on a ketogenic diet, and this may be helpful in some cases. Children with AS are at risk for medication over-treatment because their movement abnormalities or attention deficits can be mistaken for seizures and because EEG abnormalities can persist even when seizures are controlled.
1. Boyd SG, Harden A and Patton MA. The EEG in early diagnosis of the Angelman (happy puppet) syndrome. Eur J Pediatr, 1988. 147(5): p. 508-13.
2. Laan LA and Vein AA. Angelman syndrome: is there a characteristic EEG? Brain Dev, 2005. 27(2): p. 80-7.
3. Clayton-Smith J and Laan L. Angelman syndrome: a review of the clinical and genetic aspects. J Med Genet, 2003. 40(2): p. 87-95.
4. Kuenzle C, Steinlin M, Wohlrab G, et al. Adverse effects of vigabatrin in Angelman syndrome. Epilepsia, 1998. 39(11): p. 1213-5.