Epilepsy and its management

What is Epilepsy?

• Epilepsy is a chronic neurological disorder characterized by recurrent seizures associated with disturbance of consciousness and characteristic body movement (convulsion) and sometimes autonomic hyperactivity. These seizures happen when the brain’s electrical impulses act abnormally and send erratic signals.
• It affects people of all ages and results in social, behavioral, health and economic consequences to the patients and their families. It is estimated that more than 50 million people worldwide are affected. Epilepsy cannot be cured but it can be managed well with the help of medication and other treatment. The medicine used to treat symptoms of epilepsy are called anticonvulsant drugs.

Diagnosis of epilepsy

• Electroencephalography (EEG) is the most important tool for diagnosis of epilepsy. Video-EEG monitoring helps in confirming seizure type estimating the epileptogenic zone in the brain, particularly when neuroimaging is normal, and surgery is being considered.
• Computered Tomography (CT) scans are useful in emergent conditions, but focal lesions are detected only in 30 percent of patients. Magnetic Resonance Imaging (MRI) can be used to investigate about focal lesions, to know about aetiology of epilepsy and presurgical evaluation when possible.
• Functional imaging studies such as positron emission tomography (PET) and single photon emission CT (SPECT) can help to identify and confirm the ictal focus to facilitate surgical intervention for refractory focal epilepsies.

Management of epilepsy

• Most epileptic patients with adequate treatment, can lead a normal life. Early diagnosis and treatment of seizure disorder with a single appropriate agent is the best way of achieving prolonged seizure-free periods with lowest risk of toxicity. Before initiating the treatment, it is very necessary to confirm whether the seizures are due to epilepsy or any other reasons. Following points should be considered:
  • Are the fits truly epileptic and not due to other reasons (syncope, side effect of some drugs)?
  • Is the epilepsy caused by a condition that requires treatment on its own terms (brain tumor, alcohol withdrawal)?
  • Is there risk if patient is left untreated?
  • What type of epilepsy is patient suffering from?
  • Are there some reversible or remediable factors that triggers epilepsy?

About AED (Anti epileptic Drugs)

• The ideal antiepileptic drug which completely suppress all clinical symptoms of epilepsy and doesn’t produce any side effects doesn’t exist, so the choice of drug depends upon maintaining balance between efficacy and toxicity and the type of epilepsy being treated. The therapy should be initiated with a single drug, in dosage expected to produce plasma concentration in the lower portion of the therapeutic range. The dose may be increased at appropriate interval as required to control seizures or as limited by toxicity. Plasma drug level concentration should be monitored. Mild toxicity can be managed by reducing the dose by 25-30 % and waiting for tolerance to develop. Most anti-epileptics may cause skin rashes in first few weeks of treatment so no need to stop treatment for if rashes occurs. If seizure occurs despite drug’s therapeutic level, presence of potential precipitating factors like sleep deprivation, febrile illness, drugs etc should be checked. If these factors are not present and yet seizure persists, another drug should be substituted. The alternative drug chosen should have different mechanism of action. While discontinuing the previous drug therapy, dose should be reduced gradually to prevent risk of seizure recurrence.
• If the second single drug is also inadequate, treatment comprising of two drugs simultaneously should be started. In most but not all cases, additive effects are seen. Combination of three or more drugs produce more adverse effects. Interaction of anti-epileptic drugs with other drugs (if patient is taking some other drugs also) and effect of anti-epileptic drugs in case of pregnancy should also be considered. Patients with multiple seizure types (resistant epilepsy) should be given multidrug therapy. The drugs having different mechanism of action should be combined. Their adverse effects and potential drug interactions should also be considered. In them, the initial combination should be from among the older drugs such as phenytoin, carbamazepine, phenobarbitone and valproate. If resistance persists, then a newer drug such as gabapentine, lamotrigine or topiramate is added.
• The patient who doesn’t respond to two adequate medical treatment are considered as refractory epileptic patient, according to International League Against Epilepsy (ILAE). For such patients, treatment options may be surgical treatment, diets and neurostimulation to improve seizure control and quality of life. According to recent studies intracerebral stimulation of the anterior thalamic nucleus and the NeuroPace Responsive Neurostimulator can also reduce seizure frequency and improve the quality of life in patients with refractory epilepsy.

Figure- Choice of antiepileptic drugs in various forms of seizures

Duration of therapy

• Antiseizure drugs are mostly continued for at least 2 years. If the patient is seizure-free after treatment of 2 years, therapy may be discontinued. Some patients may need treatment for their whole life. Factors associated with chances of recurrent seizures after stopping of therapy are EEG abnormalities, a known structural lesion, history if frequent seizures and abnormality on neurological exam.
• The factors associated with low risk of recurrent seizures are normal EEG, idiopathic epilepsy, onset in childhood and epilepsy controlled with single drug treatment. Before discontinuing the therapy, the clinician and patient must compare the risk of recurrent seizure and chances of potential harmful effects (effect on driving) against the effect of continuing medications (cost, adverse effects of drugs). While discontinuing the drug, it should be tapered off slowly over weeks or months.

Management of epilepsy during pregnancy

• According to research till date, there is no observed significant variation in seizure frequency during pregnancy. Some women may experience some variability during pregnancy. Pregnant women can have anti-epileptic drugs, but in a minimum dose. They are advised to continue anti-epileptic drugs during pregnancy to reduce maternal and fetal trauma associated with seizures.
• While choosing an AED for a woman of childbearing age several factors are to be considered: teratogenicity, neonatal outcomes (e.g., birth weight, head circumference), obstetrical outcomes (e.g., preterm delivery and C-section rates) as well as long-term neurodevelopmental impact (IQ, verbal and non-verbal abilities, memory, behavior and any predisposition for autism spectrum disorders). Women on AED therapy should have folic acid supplements 5mg/ day starting before the conception and should be continued throughout the pregnancy.
• Epileptic women patient has almost twice the rate of complications like toxemia, premature labor and intrapartum hemorrhage. Some AED may cause fetal malformations like cardiac defect, neural tube defect, prominent lips. The newborn from mothers who have received AED during pregnancy should be checked for congenital abnormalities.
• Neonates should receive vitamin K during birth to prevent bleeding as most AEDs promote hemorrhagic diathesis in the neonate. AED can be used safely during breast feeding. Sometimes baby may get sedated.

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