2. SEIZURESSEIZURES
Transient disturbance of cerebralTransient disturbance of cerebral
functionfunction
Abnormal paroxysmal neuronalAbnormal paroxysmal neuronal
dischargedischarge
It can beIt can be
a. acutea. acute
b. chronicb. chronic
3. EPILEPSYEPILEPSY
Collective name for group of CNSCollective name for group of CNS
disordersdisorders
With repeated occurrence of sudden andWith repeated occurrence of sudden and
transitory seizurestransitory seizures
It can beIt can be
a. primary or idiopathica. primary or idiopathic
b. secondary or symptomaticb. secondary or symptomatic
4. Nature of epilepsyNature of epilepsy
Epilepsy affects about 0.5% of theEpilepsy affects about 0.5% of the
population.population.
Seizure and convulsionsSeizure and convulsions
Caused by an asynchronous high-Caused by an asynchronous high-
frequency discharge of a group offrequency discharge of a group of
neuronsneurons
Partial seizures affect localized brainPartial seizures affect localized brain
regionsregions
Generalised seizures affect the wholeGeneralised seizures affect the whole
brain.brain.
5. Nature of epilepsyNature of epilepsy
Two common forms of epilepsy are the tonic-Two common forms of epilepsy are the tonic-
clonic fit (grand mal) and the absence seizureclonic fit (grand mal) and the absence seizure
(petit mal).(petit mal).
Animal modelsAnimal models
It may be associatedIt may be associated
with enhanced excitatory amino acid transmissionwith enhanced excitatory amino acid transmission
impaired inhibitory transmissionimpaired inhibitory transmission
abnormal electrical properties of the affected cells.abnormal electrical properties of the affected cells.
glutamate content in areas surrounding an epilepticglutamate content in areas surrounding an epileptic
focus may be increasedfocus may be increased
6. CLASSIFFICATION OFCLASSIFFICATION OF
SEIZURESSEIZURES
Partial SeizurePartial Seizure
Focal area in the brain is involvedFocal area in the brain is involved
Types:Types:
a. Simple partiala. Simple partial
No impairment of consciousnessNo impairment of consciousness
motor or sensory symptomsmotor or sensory symptoms
b. complexb. complex
with impairment of consciousnesswith impairment of consciousness
with automatismswith automatisms
7. GeneralizedGeneralized
Entire brain is involvedEntire brain is involved
Tonic-clonic/ Grand malTonic-clonic/ Grand mal
Tonic phase- loss of consciousness, rigidityTonic phase- loss of consciousness, rigidity
Clonic phase- jerking movements of entireClonic phase- jerking movements of entire
bodybody
Absence/ Petit malAbsence/ Petit mal
In childrenIn children
brief loss of consciousness (10s) blank stare,brief loss of consciousness (10s) blank stare,
blinking, facial twitchingblinking, facial twitching
MyoclonicMyoclonic
brief jerksbrief jerks
8. MOA OF DRUGSMOA OF DRUGS
1.1. Reduced the spread of excitation fromReduced the spread of excitation from
seizure foci to normal neuronsseizure foci to normal neurons
2.2. Enhancement of GABA mediated inhibitoryEnhancement of GABA mediated inhibitory
transmissiontransmission
3.3. Prevent or reduced excessive discharge ofPrevent or reduced excessive discharge of
altered neurons of seizure focialtered neurons of seizure foci
4.4. Diminution of glutaminergic excitatoryDiminution of glutaminergic excitatory
transmissiontransmission
5.5. Modification of ionic conductanceModification of ionic conductance
9. Where Does DiffusionWhere Does Diffusion
Take the Ion?Take the Ion?
Exterior
Interior
K+
5 mM
K+
5 mM
Cl-
Low
Cl-
Low
Cl-
High
Cl-
High
K+
150 mM
K+
150 mM
Na+
15 mM
Na+
15 mM
Na+
150 mM
Na+
150 mM
O
U
T
O
U
T
I
N
I
N
I
N
I
N
14. Clinical Correlation
Remember that it is the rate of action potentialRemember that it is the rate of action potential
propagation that determines neurologic function.propagation that determines neurologic function.
Determined by frequency of action potentials.Determined by frequency of action potentials.
What is a seizure?What is a seizure?
What would be the
effect on the membrane
of ⇑ Cl-
influx
during a seizure?
What would be the
effect on the membrane
of ⇑ Cl-
influx
during a seizure?
Hyperpolarization & …
⇓ seizure
activity!
28. MOAMOA
SPECIFICSPECIFIC
- enhances GABA receptor mediated- enhances GABA receptor mediated
current by opening chloride channelscurrent by opening chloride channels
- blocks excitatory responses induced by- blocks excitatory responses induced by
glutamateglutamate
- high concentration blocks Na and Ca- high concentration blocks Na and Ca
conductancesconductances
31. MOAMOA
Prolongs inactivated state of NaProlongs inactivated state of Na
channelchannel
Alters K and Ca conductanceAlters K and Ca conductance
TOXICITYTOXICITY
gingival hyperplasiagingival hyperplasia
megaloblastic anemiamegaloblastic anemia
34. CARBAMAZEPINECARBAMAZEPINE
Decrease spread of seizureDecrease spread of seizure
activity from an active focusactivity from an active focus
Blocks Na channelsBlocks Na channels
35. Anti-Epileptic DrugsAnti-Epileptic Drugs
Carbamazepine:Carbamazepine:
derivative of tricyclic antidepressantsderivative of tricyclic antidepressants
Partial and tonic clonic 1Partial and tonic clonic 1stst
lineline
similar profile of that of phenytoin, but with fewersimilar profile of that of phenytoin, but with fewer
unwanted effectsunwanted effects
effective in most forms of epilepsy (except absenceeffective in most forms of epilepsy (except absence
seizures); particularly effective in psychomotorseizures); particularly effective in psychomotor
epilepsy; also useful in trigenimal neuralgiaepilepsy; also useful in trigenimal neuralgia
strong enzyme-inducing agent; therefore, manystrong enzyme-inducing agent; therefore, many
drug interactionsdrug interactions
low incidence of unwanted effects; principallylow incidence of unwanted effects; principally
sedation, ataxia, mental disturbances, watersedation, ataxia, mental disturbances, water
retention.retention.
36. ETHOSUXIMIDEETHOSUXIMIDE
Blocks Ca channelsBlocks Ca channels
Inhibits Na and K atpaseInhibits Na and K atpase
Inhibits GABA aminotransferaseInhibits GABA aminotransferase
37. Anti-Epileptic DrugsAnti-Epileptic Drugs
Ethosuximide:Ethosuximide:
the main drug used to treat absencethe main drug used to treat absence
seizures, may exacerbate other formsseizures, may exacerbate other forms
acts by blocking T-type calcium channelsacts by blocking T-type calcium channels
relatively few unwanted effects, mainlyrelatively few unwanted effects, mainly
nausea and anorexia.nausea and anorexia.
Withdrawal is not a problemWithdrawal is not a problem
38. VALPROATESVALPROATES
Increase GABA mediatedIncrease GABA mediated
transmissiontransmission
Blocks Na channels at lowBlocks Na channels at low
concentrationconcentration
Blocks K channels at highBlocks K channels at high
concentrationconcentration
39. Anti-Epileptic DrugsAnti-Epileptic Drugs
Valproate:Valproate:
chemically unrelated to other anti-epilepticchemically unrelated to other anti-epileptic
drugsdrugs
Absence and tonic clonic 1Absence and tonic clonic 1stst
line and partialline and partial
22ndnd
lineline
mechanism of action not clear; weakmechanism of action not clear; weak
inhibition of GABA transaminase; someinhibition of GABA transaminase; some
effect on sodium channelseffect on sodium channels
related few unwanted effects: baldness,related few unwanted effects: baldness,
teratogenicity, liver damage (rare, butteratogenicity, liver damage (rare, but
serious).serious).
40. New Anti-Epileptic DrugsNew Anti-Epileptic Drugs
Topiramate:Topiramate:
complex actions, not fully understoodcomplex actions, not fully understood
Partial and tonic clonic 2Partial and tonic clonic 2ndnd
lineline
similar to phenytoin with fewer side-effects andsimilar to phenytoin with fewer side-effects and
simpler pharmacokineticssimpler pharmacokinetics
Risk of teratogenesisRisk of teratogenesis
Lamotrigine:Lamotrigine:
acts by inhibiting sodium channelsacts by inhibiting sodium channels
broad therapeutic profilebroad therapeutic profile
main side-effects are hypersensitivity reactionsmain side-effects are hypersensitivity reactions
(especially skin rashes).(especially skin rashes).
Partial 2Partial 2ndnd
lineline
41. New Anti-Epileptic drugsNew Anti-Epileptic drugs
Felbamate:Felbamate:
mechanisms of action unknownmechanisms of action unknown
Partial 3Partial 3rdrd
lineline
use limited to intractable disease because of theuse limited to intractable disease because of the
risk of severe hypersensitivity reactionsrisk of severe hypersensitivity reactions..
Gabapentin:Gabapentin:
mechanism of action not knownmechanism of action not known
Partial and tonic clonic 2Partial and tonic clonic 2ndnd
lineline
saturable absorption; therefore, it is safe insaturable absorption; therefore, it is safe in
overdoseoverdose
relatively free of side-effects.relatively free of side-effects.
42. Medications by SeizureMedications by Seizure
TypeType
(Generalized Seizures)(Generalized Seizures)
Absence (petit mal)Absence (petit mal)
brief period of unresponsiveness <30 sbrief period of unresponsiveness <30 s
11stst
line ethosuximide, valproic acidline ethosuximide, valproic acid
22ndnd
line lamotrigineline lamotrigine
Tonic-clonic (grand mal)Tonic-clonic (grand mal)
dramatic convulsions and loss ofdramatic convulsions and loss of
consciousnessconsciousness
11stst
line valproic acid,line valproic acid,
carbamazepine,phenytoincarbamazepine,phenytoin
22ndnd
line lamotrigine, phenobarbitalline lamotrigine, phenobarbital
43. Medications by SeizureMedications by Seizure
TypeType
(Partial Seizures)(Partial Seizures) Simple PartialSimple Partial
Sensory seizureSensory seizure
11stst
line carbamazepine, phenytoinline carbamazepine, phenytoin
22ndnd
line lamotrigine, gabapentin, valproic acidline lamotrigine, gabapentin, valproic acid
Complex PartialComplex Partial
Starts at simple partial and generalizesStarts at simple partial and generalizes
11stst
line carbamazepine,phenytoinline carbamazepine,phenytoin
22ndnd
line lamotrigine, gabapentinline lamotrigine, gabapentin
Unremitting seizureUnremitting seizure respiratory compromiserespiratory compromise
11stst
line lorazepam, diazepamline lorazepam, diazepam
22ndnd
line phenytoinline phenytoin