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EPILEPSY

EPILEPSY. Md. Amran Howlader Lecturer of Dept. of Pharmacy SEU. 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.

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EPILEPSY

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  1. EPILEPSY Md. Amran Howlader Lecturer of Dept. of Pharmacy SEU

  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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