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Epilepsy: Causes, Seizures, and Treatments

Discover the causes, types of seizures, and available treatments for epilepsy. Learn about famous people affected by epilepsy and the role of GABA in seizure inhibition.

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Epilepsy: Causes, Seizures, and Treatments

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  1. EPILEPSY D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY

  2. INTRODUCTION • PERIODIC AND UNPREDICTABLE SEIZURES CAUSED BY THE RHYTHMIC FIRING OF LARGE GROUPS OF NEURONS • MAY RANGE FROM MILD TWITCHING TO LOSS OF CONSCIOUSNESS AND UNCONTROLLABLE CONVULSIONS

  3. SOME FAMOUS PEOPLE WHO WERE AFFLICTED • ALEXANDER THE GREAT • JULIUS CAESAR • NAPOLEON • DOSTOEVSKY • VAN GOGH

  4. CAUSES OF EPILEPSY • ACUTE • CONGENITAL

  5. CAUSES OF ACUTE EPILEPSY • CORTICAL DAMAGE • TRAUMA • STROKE • NEOPLASM • AUTOIMMUNE EFFECTS (RASMUSSEN’S ENCEPHALITIS)

  6. CAUSES OF CONGENITAL EPILEPSY • DYSGENESIS (FAILURE OF CORTEX TO GROW PROPERLY) • VASCULAR MALFORMATIONS • AT LEAST EIGHT SINGLE LOCUS GENETIC DEFECTS ARE ASSOCIATED WITH EPILEPSY. MOST FORMS INVOLVE INHERITING MORE THAN ONE LOCUS. (EXAMPLES: JUVENILE MYOCLONIC, PETIT MAL)

  7. EPILEPTIC SEIZURE FOCI • MOTOR CORTEX: CAUSE MOVEMENTS ON CONTRALATERAL SIDE ACCORDING TO THE SOMATOTOPIC LOCATION OF THE SEIZURE FOCUS. • SOMATOSENSORY CORTEX: CAUSE AN EPILEPTIC AURA IN WHICH A SENSATION IS EXPERIENCED. ALSO DEPENDS ON WHICH PART OF SOMATOTOPIC REPRESENTATION HOLDS THE FOCUS. • VISUAL CORTEX: CAUSE A VISUAL AURA (SCINTILLATIONS, COLORS).

  8. EPILEPTIC SEIZURE FOCI (Cont.) • AUDITORY CORTEX: CAUSE AN AUDITORY AURA (HUMMING, BUZZING, AND RINGING). • VESTIBULAR CORTEX: CAUSE A FEELING OF SPINNING. • TEMPORAL LOBE: CAUSE COMPLEX BEHAVIORS. • OLIFACTORY CORTEX: CAUSE MALODOROUS AURA. • HIPPOCAMPUS: PARTICULARLY SUSCEPTIBLE AND A FREQUENT SOURCE OF EPILEPTIC ACTIVITY.

  9. TWO TYPES OF SIEZURES • PARTIAL • GENERAL

  10. PARTIAL SEIZURES • IN MOTOR CORTEX - RESULTS IN LOCALIZED CONTRACTIONS OF CONTRALATERAL MUSCLES THAT MAY SPREAD TO OTHER MUSCLES FOLLOWING THE SOMATOTOPIC ORGANIZATION OF THE MOTOR CORTEX • COMPLEX PARTIAL SEIZURES MAY OCCUR IN PSYCHOMOTOR EPILEPSY. THESE ORIGINATE IN THE LIMBIC LOBE AND RESULT IN ILLUSIONS AND SEMIPURPOSEFUL MOTOR ACTIVITY • DURING AND BETWEEN FOCAL SEIZURES, SCALP RECORDINGS MAY REVEAL EEG SPIKES.

  11. GENERALIZED SEIZURES • INVOLVE WIDE AREAS OF THE BRAIN AND LOSS OF CONSCIOUSNESS • PETIT MAL • GRAND MAL

  12. TWO TYPES OF GENERAL SEIZURES • PETIT MAL SEIZURES: CONSCIOUSNESS IS TRANSIENTLY LOST AND THE EEG DISPLAYS SPIKE AND WAVE ACTIVITY. • GRAND MAL SEIZURES: CONSCIOUSNESS LOST FOR A LONGER PERIOD AND THE INDIVIDUAL WILL FALL IF STANDING WHEN SEIZURE STARTS. .TONIC PHASE: GENERALIZED INCREASED MUSCLE TONE. .CLONIC PHASE: SERIES OF JERKY MOVEMENTS. BOWEL AND BLADDER MAY EVACUATE.

  13. ELECTROPHYSIOLOGICAL CORRELATES OF SEIZURE ACTIVITY • EEG SPIKES THAT OCCUR BETWEEN FULL-BLOWN SEIZURES ARE CALLED INTERICTAL SPIKES. • THESE ARISE FROM LONG-LASTING DEPOLARIZATIONS CALLED DEPOLARIZATION SHIFTS.

  14. EEG TRACING OF EPILEPTIC SIEZURE

  15. DEPOLARIZATION SHIFTS • TRIGGER REPETITIVE ACTION POTENTIALS IN CORTICAL NEURONS • REGENERATIVE CALCIUM MEDIATED DENDRIDIC POTENTIALS IN CORTICAL NEURONS • REDUCTION OF INHIBITORY INTERACTIONS IN CORTICAL CIRCUITS • RELEASE OF POTASSIUM AND EXCITATORY AMINO ACIDS FROM HYPERACTIVE NEURONS • EXCITATION OF NMDA- TYPE GLUTAMATE RECEPTORS [N-METHYL-D-ASPARTATE, GLUTAMATE ANALOG]. (CALCIUM ENTRY AND LONG TERM POTENTIATION [LTP]). SEIZURES ACTIVATE NMDA RECEPTORS AND STRENGTHEN CONNECTIONS BETWEEN EXCITED NEURONS.

  16. TREATMENTS FOR EPILEPSY • NO EFFECTIVE PREVENTIONS OR CURES KNOWN. • SURGICAL METHODS • SEIZURE INHIBITING DRUGS

  17. SURGICAL METHODS • SURGICAL REMOVAL OF EPILEPTOGENIC REGION • CUTTING CORPUS CALLOSUM TO PREVENT SPREAD OF SEIZURES BETWEEN HEMISPHERES

  18. SEIZURE INHIBITING DRUGS • SEIZURES CAN ARISE FROM REMOVAL OF GABA INDUCED INHIBITION WHEN GABA LEVELS DROP • VITAMIN B6 (PYRIDOXAL PHOSPHATE) IS IMPORTANT FOR GABA SYNTHESIS • MOST GABA IS EVENTUALLY CONVERTED TO SUCCINATE BY GABA AMINOTRANSFERASE • A GABA AMINOTRANSFERASE INHIBITOR, SODIUM DIPROPYLACETATE, IS WIDELY USED AS AN ANTICONVULSANT • GABA IS MOST COMMONLY FOUND IN LOCAL-CIRCUIT INTERNEURONS • DRUGS THAT ACT AS AGONISTS OR MODULATORS FOR POSTSYNAPTIC GABA RECEPTORS, SUCH AS BARBITURATES, ARE ALSO USED TO TREAT EPILEPSY

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