Aetiology
The incidence of SE varies by age, with the highest risk seen in infants and individuals over 50 years old. [8]
In children, the most common aetiologies are infective. In adults, the most common aetiology is cerebrovascular disease.
The underlying aetiology of SE can be divided into three groups:
1.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 [5]
2. Future epilepsy onset
In one-third of patients, the episode will represent the onset of future epilepsy.
3. 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.