Epilepsy

Aetiology

Epilepsy may be attributed to an identifiable underlying cause in some people, yet in others no underlying cause is found. The illness also can be hereditary.

Epilepsy can result from an underlying brain disorder, such as former brain anoxia during delivery, a brain tumour or stroke, from brain damage incurred by brain trauma, such as a severe blow to the head or surgery, or as a result of brain infection, eg encephalitis or meningitis.

For the majority of people with epilepsy, the cause of their illness cannot be identified and may be attributed to an imbalance of neurotransmitters in the brain. This is usually the case in children with epilepsy, and the older the person with epilepsy is, the more likely it may be that epilepsy is caused by an underlying brain disease.

Together with a family history of seizures, use of antidepressant drugs, discontinuation of benzodiazepines and alcohol misuse are risk factors associated with epilepsy. In addition, low blood sugar and changes in electrolytes (especially sodium) can cause seizures.

What happens in the brain

The areas of the brain implicated in partial and general seizure .

During a seizure, neurons in the cerebrum create abnormally increased electrical activity, preventing the brain from processing normal signals. The seizure activity may be localised, which may induce symptoms from the cortical regions, eg motor cortex, inducing abnormal motor activity or in the temporal  lobe causing gastrointestinal symptoms. If the seizure spreads to other regions, other brain functions may be involved which results in a generalised seizure.

Changes in glial cell division and loss of neurons in the brain have been identified in people with epilepsy, and a loss of the neurons containing the inhibitory neurotransmittergamma aminobutyric acid (GABA) has been implicated in the disorder. Whether these changes are the cause or the consequence of the seizure is uncertain.

 Further information on the forebrain