This page compiles our content related to seizure disorder. For further information on diagnosis and treatment, follow the links below to our full BMJ Best Practice topics on the relevant conditions and symptoms.
A seizure is defined as "a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain." Epilepsy is considered to be a disease of the brain defined by any of the following conditions: ILAE: EpilepsyDiagnosis.org Opens in new window
At least two unprovoked (or reflex) seizures occurring more than 24 hours apart
One unprovoked (or reflex) seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10 years
Diagnosis of an epilepsy syndrome.
A life-threatening neurologic condition defined as 5 or more minutes of either continuous seizure activity or repetitive seizures without regaining consciousness. Status epilepticus can equally occur in patients with an established diagnosis of epilepsy or as the first unprovoked seizure in patients with no known history of epilepsy. Generalized convulsive status epilepticus in both its subtle and overt subtypes constitutes the most frequent variant. Recognition is crucial because rapid termination helps prevent serious brain injury, especially in patients with impaired consciousness.
Generalized seizures (generalized tonic-clonic seizures [GTCS]) classically involve loss of consciousness and a phasic tonic stiffening of the limbs, followed by repetitive clonic jerking. Most GTCS are self-limiting without intervention. The electroencephalogram (EEG) shows bisynchronous epileptiform activity in both cerebral hemispheres. GTCS occur in many different types of epilepsy. GTCS may also be provoked by an insult in an individual who does not have epilepsy.
Seizures may occur as a stand-alone event or may be recurrent. Key risk factors include genetic predisposition or family history, perinatal asphyxia, metabolic/neurodegenerative disorders, head trauma, or structural abnormalities of the central nervous system. Detailed history is of paramount importance in the diagnosis, as key diagnostic factors lie in the history as opposed to ancillary investigations.
Seizures occurring in a febrile child, between the ages of 6 and 60 months, without evidence of intracranial infection, metabolic disturbance, or history of afebrile seizures. Febrile seizures are common in childhood. The cumulative incidence is estimated to be between 2% and 5% in the US and Western Europe, between 6% and 9% in Japan, and 14% in India and Guam. Most febrile seizures resolve spontaneously and do not require acute or long-term anticonvulsant treatment.
Typically characterized by abrupt cessation of activity and responsiveness, lasting between 5 to 10 seconds, with minimal associated movements and no aura/postictal state. Typical absence seizures may be precipitated by hyperventilation and photic stimulation. EEG is the definitive test. Most typical absence seizures are medically responsive, and childhood absence epilepsy (CAE) tends to remit by adulthood. Atypical absence seizures have a less distinct beginning and end, and are not usually precipitated by hyperventilation. Atypical absence seizures tend to be medically refractory and associated with intellectual disability.
Focal (partial) seizures are the electrical and clinical manifestations of seizures that arise from one portion of the brain. They may occur in the context of an underlying structural brain abnormality, or may be idiopathic. The EEG typically indicates a localized discharge over the area of onset, or regions beyond the initial onset as the abnormal electrical activity propagates. The temporal lobe is the most common area of onset for focal seizures, but they may arise from any lobe. Consciousness is preserved in focal aware seizures, whereas focal impaired awareness seizures feature memory loss for the duration of the clinical event or impaired responsiveness at the time of the event. Focal seizures may evolve into bilateral tonic-clonic seizures.
An epilepsy syndrome typically presenting in infancy, with a varying etiology. Spasms may be flexor, extensor, mixed flexor-extensor, symmetrical or asymmetrical, and typically occur in clusters. A hypsarrhythmic pattern on EEG is characteristic, but not universally present at all times. Infantile spasms are often associated with an underlying disorder. Where no underlying cause is detected and there is normal development prior to onset, the prognosis tends to be better.
Syncope is a sudden and transient loss of consciousness that is associated with a loss of postural tone, and resolves spontaneously and completely without intervention. Differentiating between syncope and epileptic seizures can sometimes be challenging. Twitching and jerking are often seen with vasovagal or cardiac syncope, which can be differentiated from rhythmic jerking of all the limbs in tonic-clonic seizures. Loss of bowel and bladder control, commonly seen with seizures, is rare during syncope. The presence of an aura and unconsciousness for >5 minutes is more typical of a seizure.
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This overview has been compiled using the information in existing sub-topics.
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