Epilepsy

Introduction

Epilepsy is a condition characterised by paroxysmal (convulsions) episodes of sudden, involuntary muscle contractions. It refers to seizures, with or without alterations in consciousness, behaviour, sensation, and autonomic function. The episodes may be partial - involving only some parts of the body or generalised - involving the whole body. These episodes are labelled epilepsy, if the attacks are recurrent. Seizures affect about 1% of the world's population, and 25% of the affected patients have chronically recurring seizures known as epilepsy. In ancient days, it was believed that epilepsy was caused by magic and other supernatural forces. The role of electro-chemical imbalances and pathological changes in the brain has been recognised as the actual cause of the condition only in the last few decades.





Cause and Pathogenesis


The cause of the seizures may be idiopathic (without identifiable cause) or secondary to identifiable causes. The causes that have been identified include pathologic processes in the brain (for example: Haemorrhage, tumours, trauma or injury, acute cerebral oedema , infection, and degenerative changes in the brain tissue), endogenous or exogenous toxic substances and chemicals (for example: uraemia, lead poisoning, alcohol intoxication or drugs), metabolic disturbances, severe pyrexia (high fever) and developmental abnormalities, birth defects, and genetic and hereditary factors. The development of seizures result from a generalised disturbance of the brain function wherein there is abnormal electrical activity within the brain. It results when an internal or external stimulus causes abnormal hypersynchronous discharges in a focal area of the brain that then spreads throughout the brain. Associated with the abnormal electrical activity is a series of complex chemical changes within the brain that are even today only partially understood. Thus a complex interaction of electro-chemical factors is responsible for the seizures in epilepsy.





Symptoms and Signs

The signs of a seizure depend upon the type of seizure.

Generalised seizures affect both the consciousness and motor function from the onset and affect the whole body.
Absence seizures usually last 10 to 30 seconds and may involve just twitching and loss of contact with the environment.
Myo-clonic seizures involve intermittent contraction of muscles.
Clonic seizures involve intermittent muscle contractions and loss of consciousness for several minutes.
Tonic seizures are marked by prolonged involuntary muscle contraction and loss of consciousness for 30-60 seconds.
Tonic-clonic seizures, one of the most common types, involve loss of consciousness with prolonged contraction of the muscles, followed later by intermittent muscle contractions and then a flaccid state of the body.
Thus, the type of seizure determines the symptoms and signs. The convulsive episode may be preceded by an aura of a fit, hallucinations and a sense of déjà vu. Bladder and bowel disturbances may occur during a seizure. After the seizure subsides, the patient may be in a state of confusion, which may last as long as a day or more. During this period, the patient may have some transient neurological deficit which disappears within a day or so.





Investigations and Diagnosis

Epilepsy is diagnosed by a detailed history and clinical examination along with a few specific investigations. The main priority of diagnosis is to distinguish idiopathic seizure activity from symptomatic activity. Electroencephalogram (EEG) is routinely taken to identify the area of abnormal discharge in the brain. Computed Tomography (CT-Scan) and Magnetic Resonance Imaging (MRI) may be used to detect pathologies like brain tumours, and haematomas. A Skull X-ray is useful to detect evidence of fractures, bony erosions, and separated sutures. Cerebral Angiography may be helpful to detect vascular abnormalities and subdural haematoma. Urine Examination may be necessary to detect toxicity caused by drugs and chemicals. Blood Tests may be done to identify hypoglycemia, electrolyte imbalances, increased blood urea nitrogen, and increased blood alcohol levels, all of which may influence the development of seizures.





Treatment and Prognosis

General treatment and first aid
During the seizure, safety precautions must be taken to prevent injury (for example: loosen restrictive clothing, roll on side to prevent aspiration, place a small pillow under the head). Prevent blockage of the airway, note frequency of seizures, type, time, involved body parts, and length of seizure, monitor vital signs and the neurologic status. Place a wad in between the teeth to prevent biting of the tongue.

Drug therapy

This is the mainstay of treatment. Various anticonvulsants like Phenytoin, Phenobarbitone, Carbamazepine, Sodium Valproate, and Benzodiazepines are useful in controlling seizures and preventing recurrence. For specific seizures, there are individual drugs that produce the best results. Treatment for epilepsy where there is no cause may need to be continued for years, sometimes for as long as five years or more after the last episode of seizure.

Surgery

Rarely, surgical intervention by resection of epileptic focus or stereotactic lesions in the brain may be required to produce good control of seizures.

Complications

These may occur as a result of the onset of seizure activity and can include injury from a fall or from jerking, as well as airway occlusion and aspiration. A condition known as status epilepticus, in which motor, sensory or psychic seizures follow one another with no intervening periods of consciousness, is a medical emergency and may be fatal.

Prevention


Episodes of seizures can be prevented by eliminating causative or precipitating factors. A normal lifestyle should be encouraged, wherever possible. Moderate exercise and participation in sports with proper safeguards may be permitted. Driving vehicles or operating heavy machinery should be avoided, if possible. Alcohol should be avoided. Anticonvulsant blood levels and possible side effects of the drugs should be clinically monitored regularly. Counselling that includes information about the importance of taking medications regularly should be given to the patient and family members.