Idiopathic Generalised Epilepsy (IGE)

This flashcard set covers the characteristics, EEG patterns, and specific syndromes of Idiopathic Generalised Epilepsy (IGE), including Childhood Absence Epilepsy and Juvenile Myoclonic Epilepsy, based on the lecture material.

Idiopathic Generalised Epilepsy (IGE) Characteristics

A syndrome characterized by a normal inter-ictal state, no neurological signs or symptoms, generalized seizures, generalized EEG expression (synchronous and symmetrical), and normal neuroimaging; presumed to be genetic.

Inter-ictal discharges

EEG abnormalities that occur between seizures, which in IGE include spikes, polyspikes, spike-wave ($SW$), and polyspike-wave ($PSW$).

Myoclonic seizures

Shock-like, irregular, and arrhythmic jerks lasting for $300-500\,ms$; they can be singular or repetitive and predominantly affect the eyelids, facial/neck muscles, and upper limbs.

Simple absence seizures

A type of typical absence seizure consisting of mild, moderate, or severe impaired consciousness without other significant motor symptoms.

Complex absence seizures

A type of typical absence seizure that includes impaired consciousness along with motor manifestations such as myoclonia, atonia, clonus, automatisms, or autonomic symptoms.

Generalized Tonic Clonic Seizures (GTCS) Timing

In IGE, these seizures occur without aura and are often preceded by myoclonic jerks or absence seizures; in $17-53\%$ of cases, they occur specifically on awakening.

Homotopic regions

Corresponding parts of both cerebral hemispheres where inter-ictal discharges in IGE appear with similar morphology, amplitude, and timing.

EEG Asymmetries

Common variations in IGE where discharges may begin $10-25\,ms$ earlier or have maximal amplitude in one hemisphere, with the site of maximum shift between hemispheres during recording.

Fragmentation of Discharge

The breakdown of regular patterns into multiple spikes, irregular spike and wave, or slowing alone; very common in JME and occurs increasingly during drowsiness and sleep.

Childhood Absence Epilepsy (CAE)

An IGE syndrome with an age of onset between $4-10$ years, characterized by very frequent, brief ($4-20\,sec$) absences and ictal EEG showing bilateral, synchronous $3\,Hz$ GSWD.

Occipital intermittent rhythmic delta activity (OIRDA)

An EEG pattern common in $33\%$ of CAE cases that serves as a good prognostic feature, indicating a $> 50\%$ chance of spontaneous remission within 10 years.

Bad prognostic features in CAE

EEG findings suggesting a child is likely to develop tonic-clonic seizures and has only a $6\%$ chance of spontaneous remission; these include photoparoxysmal response and the absence of OIRDA.

Juvenile Myoclonic Epilepsy (JME)

A syndrome appearing around puberty featuring arrhythmic myoclonic jerks (often in the arms) within $30$ minutes to $1$ hour of awakening, often triggered by sleep deprivation, fatigue, or alcohol.

JME EEG Pattern

Interictal and ictal activity characterized by rapid generalized spike-and-wave and polyspike-and-wave at a frequency of $4-6\,Hz$.

Epilepsy with generalized tonic-clonic seizures only

A lifelong syndrome where GTCS occur $1$ to $2$ hours after awakening or during relaxation, with an $83\%$ incidence of relapse upon treatment withdrawal.

Epilepsy Syndrome Diagnosis

A crucial clinical distinction where management and prognostication (e.g., IGE vs. SGE) depend on the specific syndrome identified through EEG and clinical signs, rather than just a general diagnosis of epilepsy.