Atonic seizure

Disease modifying treatment available:
Time critical diagnosis and management:
Lateralising:

Definition

Atonic seizures are generalised onset seizures that cause a sudden loss in muscle tone (less than two seconds) and can involve the head, trunk or limbs. There are no preceding myoclonic or tonic features.

Taxotomy

Aetiology

None

Supercategory
Generalized seizure

Disorder	Clinical features	Associated features	Investigations	Disease modifying treatment available	Time critical
Myoclonic epilepsy with ragged-red fibers	Epilepsy Myoclonic seizure Cerebellar ataxia Dementia Sensorineural hearing loss Optic neuropathy Generalized tonic-clonic seizure Absence seizure Proximal muscle weakness Short stature Wolff-Parkinson-White syndrome

Associated genes

Gene
CDKL5	Search ClinVar	Search ClinGen
ARX	Search ClinVar	Search ClinGen

Clinical features

Atonic seizures are characterised by a loss of muscle tone affecting the head, trunk or limbs. If there is preceding myoclonus the diagnosis is a myotonic-atonic seizure instead. The differential diagnosis includes other generalized onset seizures (myoclonic-atonic, myoclonic and tonic seizures), focal atonic seizures and causes of syncope.

Investigations