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Epilepsija (ang


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