Aetiology

The underlying aetiology of SE can be divided into three groups:

Chronic epilepsy

In one-third of patients, there will be an underlying background of chronic epilepsy.

In patients with a pre-existing history of epilepsy, SE most commonly results from:

• Drug non-compliance
• Drug withdrawal
• Drug therapy alteration

However, it may also occur in the presence of:

• Intercurrent illness
• Metabolic abnormalities
• Co-ingestion of drugs that lower the seizure threshold [4]

Future epilepsy onset

In one-third of patients, the episode will represent the onset of future epilepsy.

No prior or future history

In one-third of patients, the episode occurs with no prior or future history of epilepsy.

In the absence of an established diagnosis of epilepsy, SE may result from:

• Drug withdrawal syndromes (alcohol, barbiturates, benzodiazepines)
• Acute structural brain injury (e.g. stroke, subarachnoid haemorrhage, trauma and cerebral hypoxia)
• CNS infection (meningitis, encephalitis and abscess)

These may also be the causes of SE in a patient without epilepsy and should always be borne in mind when assessing patients.