Generalized Epilepsies Flashcards
Epilepsy with myoclonic astatic seizures (EM-AS; Doose syndrome)
Demographics:
Approximately 1 to 2% of all childhood epilepsies. Two thirds are boys.
Epilepsy with myoclonic astatic seizures (EM-AS; Doose syndrome)
Age range of onset
Onset is between seven months and six years (peak 2–4 years).
Epilepsy with myoclonic astatic seizures (EM-AS; Doose syndrome)
Semiology
Febrile or afebrile generalized tonic clonic seizures may precede the myoclonic seizures by several months
Myoclonic astatic seizures are the defining symptoms (100% of the cases).
Isolated atonic seizures and absences seizures also occur frequently, sometimes many times per day.
Tonic seizures are an exclusion criterion.
Non-convulsive status epilepticus is common, affecting one third of the patients.
Epilepsy with myoclonic astatic seizures (EM-AS; Doose syndrome)
Etiology
Genetically determined with a multifactorial polygenic fashion with variable penetrance.
Epilepsy with myoclonic astatic seizures (EM-AS; Doose syndrome)
EEG
In the initial stages, rhythmic theta activity in the midline may be the only significant finding.
When myoclonic – atonic seizures appear, there are frequent clusters of Irregular 2-3 Hz GPSWD.
Atonia is usually concurrent with the slow wave of a single or polyspike–wave complex.
The myoclonus of EM-AS appears to be a primarily generalized epileptic phenomenon, which differs from that of Lennox–Gastaut syndrome, which originates from the frontal cortex spreading to contralateral and ipsilateral cortical areas.
Epilepsy with myoclonic astatic seizures (EM-AS; Doose syndrome)
Prognosis
Half of patients achieve a seizure-free state and normal or near-normal development. These may correspond to the idiopathic form of EM-AS.
Childhood absence epilepsy (CAE, pyknolepsy)
Demographics:
Two-thirds are girls. Prevalence is about 10%.
Epilepsy with myoclonic astatic seizures (EM-AS; Doose syndrome)
Diagnostic Criteria
Inclusion criteria:
Normal development prior to the onset of seizures
Normal MRI
Onset of myoclonic, myoclonic – atonic or atonic seizures between seven months and six years of age.
Normal background EEG with 2–3 Hz GPSWD without focal spikes.
Exclusion criteria:
Dravet syndrome, Lennox – Gastaut syndrome, myoclonic epilepsy in infancy.
Tonic seizures
The differential diagnosis is mainly with benign myoclonic epilepsy in infancy , Dravet syndrome, Lennox–Gastaut syndrome and late-onset West syndrome. In general, children with EM-AS are normal prior to the development of seizures, have a strong family history of IGE, and the background EEG and brain imaging are normal.
A similar, but reversible, clinico-EEG condition may be induced by carbamazepine, oxcarbazepine and lamotrigine in a few children with rolandic sei zures or Panayiotopoulos syndrome. This possibility should be considered in children with benign focal seizures and dramatic deterioration after treatment with these drugs.
Childhood absence epilepsy (CAE, pyknolepsy)
Age range of onset
Onset is between 4 and 10 years of age (peak at 5–7 years).
Childhood absence epilepsy (CAE, pyknolepsy)
Semiology
Absences are severe and frequent.
The hallmark of the absence is abrupt, brief and severe impairment of consciousness with unresponsiveness and interruption of the ongoing voluntary activity.
Automatisms occur in two thirds of the seizures, the most common being mild myoclonic elements of the eyes, eyebrows and eyelids.
Other seizures are not compatible with CAE. The only exception is febrile convulsions prior to the onset of absences. Absence seizures are commonly brought on by hyperventilation.
Exclusion criteria for CAE:
other types of seizures; truncal myoclonia (however mild myoclonic elements maybe be present); mild or no impairment of consciousness during 3 Hz discharges; poly spikes – more than three; visual (photic) precipitation of seizures.
Childhood absence epilepsy (CAE, pyknolepsy)
Prognosis
Excellent. 60% chance of remission in the absence of GTCS or myoclonia.
Childhood absence epilepsy (CAE, pyknolepsy)
EEG
Of note – in typical cases, only EEG is needed. Normal background. 3 Hz GSWD. Spikes representing fragments are common.
The myoclonic jerk coincides with the spike component of the discharge.
Childhood absence epilepsy (CAE, pyknolepsy)
Etiology
Genetically determined but the precise mode of inheritance remains unidentified.
In monozygotic twins 84% had 3 Hz GSWD.
Current evidence suggests that mutations in genes encoding GABA receptors or voltage dependent calcium channels underlie CAE.
Recent evidence suggests that CAE is caused by abnormalities in the T type Ca channels in the thalamus.
Epilepsy with myoclonic absences (MAE)
Demographics:
Boys predominate. MAE is very rare.
Epilepsy with myoclonic absences (MAE)
Prognosis
Nearly half of the children having paired cognitive functioning prior to the onset of absences but these are probably symptomatic cases. Half of the idiopathic children develop cognitive and behavioral impairment.
The seizures are often resistant to treatment. The three meant usually requires high doses of valproate often in combination with ethosuximide.
Epilepsy with myoclonic absences (MAE)
Age range of onset
From the first months of life to the early teens (peak at seven years).
Epilepsy with myoclonic absences (MAE)
EEG
Background is usually normal at onset but may deteriorate. Interictal 3 Hz GPSWD.
