Epilepsy

Definition

Epilepsy is a condition characterised by recurrent seizures. A seizure is hypersynchornous neuronal activity. "Hypersynchronous", in plain English, means "unsynchronised" and "a lot". So a seizure is a lot of unsynchronised neuronal activity.

Strictly speaking, "epilepsy" is not a disease in that it is not a pathophysiological process. In fact, the colloquial term is what is medically considered "idiopathic epilepsy".

Classification Of Seizures

The first division to make is into partial and generalised which describe the area of the brain affected. The definitions are:

• Partial seizures involve a localised area of the brain
• Generalised seizures involve the whole brain

Partial Seizures

Partial seizures can be further divided into simple and complex which describe the effect on consciousness. The definitions are:

• Simple partial seizures do NOT cause a loss of consciousness
• Complex partial seizures DO cause a loss of consciousness

Generalised seizures

These always results in a loss of consciousness and as such cannot be classified in this way. The most important types of generalised epilepsy are:

• Absences
• Tonic-clonic seizures

There are four other types of seizure which are considered generalised but are less common: myoclonic seizures, clonic seizures, tonic seizures and atonic seizures.

A final addendum is those seizures which are considered epileptic but cannot be defined. These are "unclassified epileptic seizures". This is not the same a non epileptic attack disorder (NEAD) which is considered a psychogenic disorder with no area of uncontrolled, unsynchronised brain activity.

Investigations

EEG FBC Look for

• U+Es for electrolyte disturbance (hyponatraemia & hypernatraemia)
• hypoglycaemia
• INR PTT LFTs - looking for liver encephalopathy.
• CT Abscess - looking for brain abscess or tumour
• LP - if there is no CT result