Epilepsy is a neurological disorder which is characterized by abnormal activity of brain, which causes recurrent and unprovoked episodes of seizure, unusual behavior, altered sensations and sometimes loss of consciousness. These seizures can vary from brief episodes of a few seconds, to long periods of vigorous shaking which can result in physical injuries.
In approximately 6 out of 10 cases, there is no identifiable cause and therefore, it is called idiopathic epilepsy. Seizure with identifiable cause is called secondary epilepsy. The common causes of secondary epilepsy include brain damage after a trauma, stroke, brain tumor, brain infections, and metabolic disorders such as severe variations in blood sodium. Epilepsy can have genetic predisposition. Typically, epilepsy is diagnosed after occurrence of two unprovoked seizures. However, in the setting of an underlying known kncause, some clinicians diagnose it after one unprovoked seizure.
The epileptic seizures are classified into following two major classes:
1) Focal Seizures
2) Generalized Seizures
Focal (Partial) seizures
These result from abnormal activity in one part of the brain. They occur with loss of consciousness. If they start as focal seizure and develope loss of consciousness, the yare called focal (partial) seizures with generalization.
They always involve loss of consciousness and are further subdivided into following six types:
i) Tonic-clonic seizure
ii) Tonic seizure
iii) Clonic seizure
iv) Myoclonic seizure
v) Absence seizure
vi) Atonic seizure
The important part of management of epilepsy is finding the underlying cause by performing blood tests, brain imaging preferably MRI and electroencephalogram (EEG). Lumbar puncture for CSF examination can be part of workup if an infectious cause is suspected. In young patients, no cause might be found. New onset in an adult needs to include work-up to rule out mass and tumor as cause of a seizure.
The treatment of epilepsy primarily includes administration of anti-convulsant medication and is managed by general neurologists or epileptologists. The choice of anti-convulsant drug should be considered based on the type of seizure and adverse effects profile. The goal of anti-convulsive medication is to achieve a seizure-free status without major adverse effect. In approximately 60% of patients, this goal can be achieved by anti-convulsant therapy. After 2 to 5 years of successful treatment and being seizure-free, in about 70% of children and 60% of adults, drugs can be withdrawn without any recurrence of seizure. In drug resistant cases, epilepsy surgery can be an option as a last resort. Lobectomy and lesionectomy are two major kinds of surgery which are palliative and potentially curative. Newer techniques include vagal nerve stimulation (VNS) by surgical implantation of a stimulating device and NeuroPace RNS system implantation. These neuro stimulation techniques are approved by FDA for drug-resistant cases of epilepsy.
References: Fisher RS, van Emde Boas W, Blume W, et al. Epileptic seizures and epilepsy: definitions proposed by the International League Against Epilepsy (ILAE) and the International Bureau for Epilepsy (IBE). Epilepsia. 2005 Apr. 46(4):470-2.
“Epilepsy Fact sheet”. WHO. February 2016. Archived from the original on 11 March 2016.