‘Epilepsy is more than just seizures’

Epilepsy is one of the most common diseases of the brain in children and adults. It is not a single disease, but a group of very different diseases. The common denominator in all epilepsies is the enduring tendency to have repeated seizures. 

The brain is like a complex electrical jack box with billions of interwined wires and as many junctions between them. Brain cells communicate between one another through electrical transmissions. Normally, there is balanced and smooth electrical transmission going on simultaneously in many parts of the brain. 

A seizure occurs due to any disturbance in this balance that results in sudden and excessive electrical impulse. Its physical manifestation is sudden, such as loss of consciousness, unresponsiveness, up rolling of eyes or sudden falling down or jerking of limbs. Many different causes can disturb the normal brain electrical function. A simple cause is ‘low sodium’ (hyponatremia) in those over 65 years of age due to poor salt intake. 

A more common cause is traumatic brain injury in a motor vehicle accident. But such seizures stop once the underlying problem is corrected (normal sodium in the blood or the healing of brain trauma). But a proportion of patients who had brain injury develop repeated seizures months or years after the injury due to the scarred brain producing excess of local electrical impulses. 

This condition, which develops later, is called epilepsy when the patient has recurrent ‘unprovoked’ seizures. Epilepsies can be divided into two groups: focal epilepsy (when seizures commence in one particular part of the brain), and generalised epilepsy (when they commence simultaneously from both hemispheres). 

Distinguishing between the two is critical for diagnostic tests and treatment approaches. Epilepsy is clinically diagnosed after carefully analysing if the seizures are indeed unprovoked epileptic ones. For there are other phenomena that can look similar to seizures. 

Video recordings of the episodes in question, if available, help doctors distinguish between seizures and mimics in many cases. But this is rare: epilepsy is a clinical diagnosis and there is no test that will confirm or rule it out. Tests are usually performed to support the diagnosis (EEG) to know which type of epilepsy one is dealing with (EEG/video-EEG) and to detect its underlying cause (MRI, other brain scans and other tests). 

The point here is that all these tests can be normal in patients with epilepsy, thus ruling out some of the more sinister causes. The underlying cause of epilepsy is most commonly not structural brain lesion that can be seen in brain scans. The abnormal excess brain electrical activity is many a time intermittent, that is, not occurring constantly. 

So the routine EEG (brain wave test) can miss the abnormality completely. When the seizure focus is very deep down in the brain, the EEG may not detect any abnormalities. The EEG may show abnormalities that are unrelated to the patient’s episodes in question. 

So test results should be interpreted judiciously. Epilepsy in 70-80 per cent of patients can be easily controlled with anti-seizure medications. There are other options available to control epileptic seizures in those with a more difficult form of the disease.