Epilepsija (ang


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Epilepsija (ang

  1. 1. Epileptic seizures and epilepsy <ul><li>Classification </li></ul><ul><li>EEG in epilepsy diagnosis </li></ul>Rasa Žemaitaitytė
  2. 2. Definition <ul><li>Epilepsy – group of disorders of the CNS that cause a person to have recurrent, unprovoked seizures. </li></ul><ul><li>Seizure is the subjective or objective behavioral manifestation of an abnormal discharge of electricity from brain cells and its propagation in the brain. </li></ul>
  3. 3. Causes of epileptic seizure <ul><li>Genetic defects (of K+ channels and others); </li></ul><ul><li>Malformation of the brain; </li></ul><ul><li>Trauma to the brain (glial scars), tumor, bleeding or abscesses; </li></ul><ul><li>Poisoning (e.g., alcohol, drugs); </li></ul><ul><li>Inflammation, fever, cell swelling or (less likely) shrinkage; </li></ul><ul><li>Hypoglycemia, hypomagnesemia, hypocalcemia; </li></ul><ul><li>Lack of sleep, stress; </li></ul><ul><li>Ischemia or hypoxia; </li></ul><ul><li>Repetitive stimuli (e.g., a flickering light, noise). </li></ul>
  4. 4. Mechanisms of development <ul><li>Paroxysmal activation of Ca 2+ channels </li></ul><ul><li>Hypomagnesia </li></ul><ul><li>[K + ] extracellular  K + efflux </li></ul><ul><li>Glutamate from exicatory synapses </li></ul><ul><li>Lack of energy  impairment of Na+/K+-ATPase </li></ul><ul><li>Lack of GABA from inhibitory synapses </li></ul>DEPOLARIZATION EPILEPTIC SEIZURE
  5. 5. Classification of epileptic seizures ( International League Against Epilepsy (ILAE), 1981) <ul><li>1) Partial (focal, local) seizures </li></ul><ul><li>Simple partial seizures </li></ul><ul><ul><li>With motor signs </li></ul></ul><ul><ul><li>With somatosensory or special sensory symptoms </li></ul></ul><ul><ul><li>With autonomic symptoms and signs </li></ul></ul><ul><ul><li>With physic symptoms </li></ul></ul><ul><li>Complex partial seizures </li></ul><ul><ul><li>Simple partial onset followed by impairment of consciousness </li></ul></ul><ul><ul><li>With impairment of consciousness at onset </li></ul></ul><ul><li>Partial seizures evolving to secondarily generalized seizures </li></ul><ul><ul><li>Simple partial seizures evolving to generalized seizures </li></ul></ul><ul><ul><li>Complex partial seizures evolving to generalized seizures </li></ul></ul><ul><ul><li>Simple partial seizures evolving to complex partial seizures evolving to generalized seizures </li></ul></ul><ul><li>2) Generalized (convulsive or nonconvulsive) seizures </li></ul><ul><li>Absence seizures </li></ul><ul><ul><li>Typical absence </li></ul></ul><ul><ul><li>Atypical absence </li></ul></ul><ul><li>Myoclonic seizures </li></ul><ul><li>Clonic seizures </li></ul><ul><li>Tonic seizures </li></ul><ul><li>Tonic – clonic seizures </li></ul><ul><li>Atonic seizures </li></ul>3) Unclasiffied seizures
  6. 6. Classification of epilepsy <ul><li>Grand mal epilepsy – tonic-clonic seizures: </li></ul><ul><ul><li>Bilateral tonic and clonic movements </li></ul></ul><ul><ul><ul><li>Clonic phase – alternate contraction and relaxation of skeletal muscle (“jerking”) </li></ul></ul></ul><ul><ul><ul><li>Tonic phase – steady contraction of the muscle (“stiff-ending”) </li></ul></ul></ul><ul><ul><li>Loss of consciousness </li></ul></ul><ul><ul><li>Often tongue bitting and urinary incontinence </li></ul></ul><ul><ul><li>Last 1-5 minutes </li></ul></ul><ul><ul><li>Postseizure depression (postical state) </li></ul></ul><ul><ul><li>EEG: high-voltage, high-frequence discharge almost in all entire cortex </li></ul></ul><ul><li>Petit mal epilepsy – absence seizures: </li></ul><ul><ul><li>3 to 30 sec of unconsciousness (or diminished consciousness) Twitch-like contractions of muscles (especially muscles of eye) </li></ul></ul><ul><ul><li>Tend to be quite frequent, can occur hundred times per day </li></ul></ul><ul><ul><li>No postseizure depression </li></ul></ul><ul><ul><li>EEG: spike and dome pattern </li></ul></ul>
  7. 7. EEG activity
  8. 8. EEG in epilepsy diagnosis <ul><li>To distinguish partial and generalized seizures if they both have same clinical picture. </li></ul><ul><li>EEG may provide a clue to the area of onset. </li></ul><ul><li>To prove epilepsy diagnosis which is not always seen clinically. </li></ul><ul><li>Techniques to provoke abnormalities: </li></ul><ul><ul><li>Sleep deprivation, </li></ul></ul><ul><ul><li>Photic stimulant, </li></ul></ul><ul><ul><li>Hyperventilation, </li></ul></ul><ul><li>NB: many people with epilepsy have normal EEGs; also normal people without epilepsy occasionally can have abnormal EEGs. </li></ul>
  9. 9. Interictal spike discharge <ul><li>Depolarization shift </li></ul><ul><li>Hyperpolarizing potential </li></ul><ul><li>Neuronal inhibition </li></ul>Traditional EEG marker for a hyperexcitable area of the cortex with high epileptogenic potential.
  10. 10. Treatment of epilepsy <ul><li>Anticonvulsant drugs - mechanisms of action (to prevent excessive depolarization of neurons): </li></ul><ul><ul><li>Prolonged inactivation of the voltage-dependant Na + channels; </li></ul></ul><ul><ul><li>Blockade of T calcium current; </li></ul></ul><ul><ul><li>Enhancement of GABA-mediated inhibition; </li></ul></ul><ul><ul><li>Antagonist action of NMDA receptor. </li></ul></ul><ul><li>Surgical therapy – after conventional medications fail to control seizures. What is done: </li></ul><ul><ul><li>To remove pathological lesions; </li></ul></ul><ul><ul><li>To interrupt the CNS pathways by witch seizure are thought to spread; </li></ul></ul><ul><ul><li>To remove areas with clearly defined focal epileptogenic effect. </li></ul></ul>
  11. 11. Summary
  12. 12. References <ul><li>Kaufman – Essentials of Pathophysiology </li></ul><ul><li>Guyton – Medical Physiology </li></ul><ul><li>Silbernagl - Color Atlas of Pathophysiology </li></ul>
  13. 13. Thank you for attention 