Generalised seizures are a common seizure type, characterised by loss of consciousness, widespread motor manifestations of tonic contractions followed by clonic jerking movements, and a suppressed level of arousal following the event.
They may reflect an underlying generalised-onset epilepsy or focal epilepsy with secondary generalisation.
An electroencephalogram (EEG) and magnetic resonance imaging are essential tests for properly diagnosing an epilepsy syndrome after a generalised tonic-clonic seizure (GTCS). During a GTCS, the EEG will demonstrate bilateral synchrony in the epileptiform activity.
After a GTCS, treatment depends on the type of epilepsy syndrome identified. Generalised-onset epilepsy is treated differently from focal epilepsy. With accurate diagnosis, most seizure disorders respond to treatment.
The primary treatment complications include lack of efficacy and adverse effects of medication, or idiosyncratic reactions.
A generalised tonic-clonic seizure is a seizure type as identified by specific clinical and electroencephalographic criteria. Clinically, this seizure type classically involves loss of consciousness and a phasic tonic stiffening of the limbs (either symmetrically or asymmetrically), followed by repetitive clonic jerking. The vast majority of these types of seizure are self-limiting without intervention. The observed manifestations of the seizure are correlated on the electroencephalogram with bisynchronous epileptiform activity in both cerebral hemispheres. These seizures can occur either in a primary fashion (with onset in a widespread or bilateral distribution) or in a secondary fashion (with onset in one hemisphere or region).
History and exam
Key diagnostic factors
- presence of risk factors
- focal neurological deficits
- focal neurological symptoms (before or after seizure)
- premonitory sensation or experience (fear, epigastric sensation, déjà vu, jamais vu)
- temporary hemiparesis
- temporary aphasia
- fever, nuchal rigidity, altered mental status
Other diagnostic factors
- neurocutaneous findings of neurological disease
- family history (extended or immediate) of generalised-onset epilepsy
- previous central nervous system (CNS) infection
- head trauma
- prior seizure events or suspected seizure events
- history of substance use
- premature birth
- multiple or complicated febrile seizures
1st investigations to order
- electroencephalogram (EEG)
- blood glucose
- electrolyte panel
- toxicology screen
- head CT
Investigations to consider
- lumbar puncture
- MRI brain
- serum prolactin
- serum creatine kinase (CK)
≥2 unprovoked generalised tonic-clonic seizures (GTCSs) without syndromic diagnosis
≥2 unprovoked GTCSs with focal-onset epilepsy
≥2 unprovoked GTCSs with generalised-onset epilepsy
- Psychogenic non-epileptic spells (PNES)
- Convulsive syncope
- Cardiac arrhythmia
- Epilepsies in children, young people and adults
- Epilepsy in pregnancy (green-top guideline no.68)
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