Epilepsy

Nota:

• May lead to Secondary Generalized Serizure

1. Simple

   Nota:

   • Without alteration of conciousness
2. Complex

   Nota:

   • With alteration of consciousness
3. Secondarily Generalized Seizures

   Nota:

   • Loss of consciousness. Involves both hemispheres. Tonic (extending rigidity) and clonic (jerking extremities) phases
4. Medication
   1. Carbamazepine

      Nota:

      • Fewer side-effects than phenytoin Well absorbed Strong enzyme-inducing agent- many interactions with other drugs 
      • Side effects include sedation, ataxia, mental disturbances, mild generalised erythematous rash and water retention
   2. Valproate

      Nota:

      • Increases GABA by: (i) Weak inhibitor of enzymes that inactivate GABA, such as GABA transaminase. (ii) May stimulate synthesis of GABA (iii) May decrease GABA turnover (iv) weak blocker of Na+ channels (v) May block NMDA-mediated responses
      • • Side effects include baldness, teratogenicity, weight gain and liver damage - liver function should be managed • Valproate has metabolic effects and increases plasma lamotrogine levels • There may be an increased risk of poly-cystic-ovary syndrome associated with valproate
   3. Phenytoin

      Nota:

      • Acts mainly by block of Na+ channels • Metabolism of phenytoin shows the characteristic of saturation • Range of plasma concentration for effectiveness prior to the appearance of side effects is ~40-100 μmol/l
      • Side effects begin to appear at plasma concentrations of ≥100 μmol/l and severe reactions at plasma concentrations of ≥150 μmol/l) Side effects include confusion, gum hyperplasia, skin rashes, anaemia and teratogenesis 

1. Absence (Petit Mal)

   Nota:

   • Brief interruption of consciousness <10 seconds
   1. Medication
      1. Ethosuximide

         Nota:

         • Mechanisms of action: Blocks of T-type Ca2+ channels • Side effects include nausea and anorexia • Cautions include avoiding abrupt withdrawal, hepatic and renal impairment
      2. Lamotrigine
      3. Valproate
2. Tonic-clonic (Grand Mal)

   Nota:

   • Sequences of tonic and clonic phases
   1. Medication
      1. Valproate
      2. Carbamazepine
      3. Lamotrigine

         Nota:

         • Mechanism of action: -Blocker of Na+ channels -Inhibits the release of glutamate • Effective in treating absence epilepsy • Side effects include sedation, dizziness, ataxia and skin rashes (Stevens-Johnson syndrome) • Cautions include close monitoring in the effect of skin rashes, consideration for withdrawal
      4. Phenytoin
3. Myclonic

   Nota:

   • Sudden involuntary muscle contraction
4. Atonic

   Nota:

   • Loss of muscle tone

Nota:

• Continuous seizures lasting at least 30 minutes.

1. Medication
   1. Lorazepam

      Nota:

      • High potency benzodiazepine  •Tolerance and dependance can develop from long term administration •Mechanism of action: positive allosteric modulator of GABA(A)receptors •Side effects include sedation and withdrawal symptoms
   2. Diazepam

      Nota:

      • Tolerance can develop with long term administration • Mechanism of action: positive allosteric modulator of GABA(A) receptors • Side effects include sedation and withdrawal symptoms
   3. Clonazepam

      Nota:

      • Tolerance can develop •Mechanism of action: positive allosteric modulator of GABA(A)receptors •Side effects include sedation and withdrawal symptoms