Introduction to Epilepsy and Its Classification

Epilepsy Introduction

• Epilepsy is a common disorder affecting 0.5-1% of the population
• Characterized by seizures, episodic neuronal discharges
• Often, no recognizable cause
• Seizures range from brief loss of attention to full convulsive seizures
• Seizures can also manifest as strange feelings or behavior

Epilepsy Classification

• Classified by seizure type:
  • Partial Seizures: Begin locally and can become generalized
    • Jacksonian Epilepsy: Repetitive jerking of a muscle group, beginning on one side of the body and spreading. Patient may not lose consciousness
    • Psychomotor Epilepsy: Stereotyped purposive movements or complex behavior
  • Generalized Seizures: Involve the whole brain, immediate loss of consciousness.
    • Tonic-Clonic Seizures (Grand Mal): Tonic phase (1 min) with muscle contraction, involuntary cry, respiratory arrest, unconsciousness. Followed by clonic phase with synchronous jerks
    • Absence Seizures (Petit Mal): Occur in children, characterized by sudden cessation of activity and staring for a few seconds with minimal motor disturbance
    • Lennox-Gastaut Syndrome: Occurs in children, associated with progressive mental retardation
    • Status Epilepticus: Continuous uninterrupted seizures, requires emergency medical treatment

Antiepileptic Drugs

• Aim to inhibit abnormal neuronal discharge, not the underlying cause
• Mechanisms of Action:
  • Enhancement of GABA Action:
    • Phenobarbital
    • Benzodiazepines
    • Vigabatrin
    • Tiagabine
  • Inhibition of Sodium Channel Function:
    • Carbamazepine
    • Phenytoin
    • Lamotrigine
    • Lacosamide
  • Inhibition of Calcium Channel Function:
    • Valproate
    • Ethosuximide
  • Novel Mechanisms:
    • Gabapentin
    • Pregabalin
    • Ganaxolone
    • Tonabersat

Phenobarbital

• Similar clinical uses to phenytoin
• Not commonly used due to sedative effects
• Widely used in veterinary practice

Carbamazepine

• One of the most widely used antiepileptic drugs
• Chemically related to tricyclic antidepressants
• Used in certain partial seizures (e.g., psychomotor epilepsy)
• Treats neuropathic pain and manic-depressive illness
• Oral administration
• Plasma half-life of 30 hours
• Strong inducer of hepatic enzymes
• Slow-release preparation available
• Side effects:
  • Nausea, anorexia
  • Lethargy, dizziness
  • Hypersensitivity reactions (rare)

Valproate

• Useful in certain types of infantile epilepsy
• Low toxicity and lacks sedative action
• Used in adolescents with tonic-clonic, myoclonic, and absence seizures
• Used for spina bifida
• Well absorbed orally and excreted
• Plasma half-life of 15 hours
• Contraindicated in pregnancy
• Side effects:
  • Ataxia
  • No convulsions

Gabapentin and Pregabalin

• Effective against partial seizures and neuropathic pain
• Less severe side effects
• Well absorbed, plasma half-life of 6 hours
• Requires dosing 2-3 times daily
• Minimal drug interactions
• Used as an analgesic for neuropathic pain
• Pregabalin is a more potent analogue of gabapentin

Benzodiazepines

• Used to treat:
  • Acute seizures, especially in children
  • Status epilepticus
  • Act rapidly
  • Examples:
    • Diazepam (rectal administration)
    • Lorazepam (IV)
    • Diazepam (IV)
    • Clonazepam (IV)

Other Uses of Antiepileptic Drugs

• Bipolar disorder (valproate, carbamazepine, oxcarbazepine, lamotrigine, topiramate)
• Migraine prophylaxis (valproate, gabapentin, topiramate)
• Anxiety disorders (gabapentin)
• Neuropathic pain (gabapentin, pregabalin, carbamazepine, lamotrigine)

Antiepileptic Drugs and Women

• May increase oral contraceptive metabolism, reducing effectiveness
• May produce teratogenic effects (fetal abnormalities)
• May cause vitamin K deficiency in newborns

Clinical Uses of Antiepileptic Drugs

• Generalized Tonic-Clonic Seizures:
  • Carbamazepine (preferred due to favorable effectiveness-risk ratio)
  • Phenytoin
  • Valproate
  • Newer agents: Vigabatrin, lamotrigine, topiramate, levetiracetam
• Partial (Focal) Seizures:
  • Carbamazepine
  • Valproate
  • Alternatives: Clonazepam, phenytoin, gabapentin, pregabalin, lamotrigine, topiramate, levetiracetam, zonisamide
• Juvenile Myoclonic Epilepsy:
  • Newer agents
• Absence Syndromes:
  • Ethosuximide
  • Valproate
  • Use of a single drug is preferred to avoid pharmacokinetic interactions

Maintenance of Medication

• Continuing therapy should be planned by a specialist
• Treatment plan should include:
  • Specific drug choices
  • Drug dose
  • Possible side effects
  • Action to take if seizures persist
• Adherence is important:
  • Educate patients and caregivers
  • Use simple medication regimens

Changes to AED Regimen

• If seizures continue despite optimal dose of first-line AED, re-evaluate the epilepsy diagnosis.
• If AED fails due to seizures or side effects:
  • Begin a second drug (alternative first- or second-line drug)
  • Combination therapy (adjunctive) should only be considered when monotherapy is ineffective.

Drug Monitoring

• Maintain vigilance for treatment-emergent adverse effects
• Blood monitoring:
  • Indications:
    • Determination of non-adherence
    • Suspected toxicity
    • Adjustment of phenytoin dose
    • Management of pharmacokinetic interactions
    • Specific clinical circumstances (status epilepticus, organ failure, pregnancy)

Discontinuation of Treatment

• Discuss risks and benefits of continuing or withdrawing medication after 2 years of seizure freedom.
• Withdrawal should be managed by a specialist.
• Extra caution with benzodiazepines and barbiturates (withdrawal may take 6 months or longer)
• Instruct patients, families, and caregivers about withdrawal.

Explore the basics of epilepsy, a disorder that affects a significant portion of the population. This quiz delves into the different types of seizures, including partial and generalized seizures, along with specific examples like Jacksonian and Tonic-Clonic seizures. Test your understanding of the characteristics and classifications associated with epilepsy.