Doose64 described a group of children with myoclonic and astatic seizures, often in combination with absence, generalized tonic-clonic, and tonic seizures. In this syndrome, astatic seizures (defined as seizures during which the patient is unable to stand) occurred suddenly, without warning, and the children collapsed onto the floor as if their legs had been pulled from under them. No loss of consciousness was apparent. At times the astatic seizures are so short that only a brief nodding of the head and slight flexion of the knees are seen. From the clinical description of these seizures, it appears that they are atonic.
In these children, the loss of postural tone often is immediately preceded by myoclonic jerks-hence the term myoclonic-astatic seizures. The myoclonic seizures in this disorder involve symmetric jerking of the arms and shoulders with simultaneous nodding of the head. Some myoclonic jerks are violent, causing the arms to fling upward, and some are so mild that they are easier to feel than see.
This disorder is more common in boys than in girls. The age of onset is between 1 and 5 years. With few exceptions, mental and motor development is normal before the onset of the illness. The prognosis is generally unfavorable, however, and dementia develops in most patients. Absence status is reported to play a role in the pathogenesis of the dementia.
The EEG pattern consists of bilaterally synchronous, regular or irregular 2- to 3-Hz spike-and-wave discharges. The background activity exhibits an excess of monomorphic theta activity.
Adapted from: Holmes GL. Classification of seizures and the epilepsies. In: Schachter SC, Schomer DL, eds. The comprehensive evaluation and treatment of epilepsy. San Diego, CA: Academic Press; 1997. p. 1-36.
With permission from Elsevier (www.elsevier.com)