Epilepsy

DEFINITION• Came from the Greek word epilepsia which

means to seize• Is a chronic neurologic disorder characterised

by seizures• The seizures are transient signs or symptoms

of abnormal, excessive but synchronous neuronal activity in the brain

• Should not be understood as a single disorder but rather as a syndrome with vastly divergent symptoms with all involving episodic abnormal electrical activity in the brain

EPIDEMIOLOGY• About 50 million people world wide have

epilepsy• About 20,000,000 cases in US• About 3,000,000 in UK• It is placed at 14-57 per thousand population

for Africa and some South American countries• Generally it has been placed at 40-70per

100,000 population for developed countries and 100-190 per 100,000 population for developing countries.

CLASSIFICATION• Epilepsies are classified in five ways• By their first cause or aetiology• By the observable manifestations of the

seizures known as semiology• By the location in the brain where the

seizures originate• As a part of discrete identifiable medical

syndromes• By the event that triggers the seizure as in

primary reading epilepsy.

CLASSIFICATIONIn 1981. the International League against

epilepsy (ILAE) proposed a classification scheme for individual seizures that is still in common use.

It is simple

ClassificationGeneralised means the source is distributed

around the brain and it involves loss of consciousnessTonic – clonicTonicClonicAbsenceAtonic

ClassificationPartial or focal when the source of the

seizure within the brain is localisedSimple: consciousness is unaffectedComplex: involving loss of consciousnessSimple with secondary generalisationComplex with secondary generalisationSimple becoming complex with secondary

generalisation

ClassificationUnclassified these are seizure types that

could not fit into any particular category

ClassificationSince 1997 the ILAE has been working on a

new scheme that have five axisIctal phenomenon ( pertaining to an epileptic

seizure )Seizure typeAetiologySyndromeImpairment

SIMPLE PARTIAL SEIZURES• Can present with the following signs

– Motor signs• Focal without a match• Focal with a match (Jacksonian )• Postural• Phonatory ( vocalisation, or arrest of speech )

– With somatosensory or special sensory symptoms e.g simple hallucinations like tingling, light flashes, buzzing.• Somatosensory• Visual

SIMPLE PARTIAL SEIZURES• Auditoy• Olfactory• Gastatory• Vertiginous

– With autonomic symptoms or signs• Epigastric sensation• Pallor• Sweating• Flushing• Piloerection• Pupillary dilatation

SIMPLE PARTIAL SEIZURESWith psychic symptoms ( disturbance of higher

centre functions ). These symptoms however, rarely occurs without impairment of consciousness and are therefore more commonly experienced as complex partial seizures Dysphasic Cognitive ( dreamy state, distortion of time ) Dysmesic e.g dejavu Affective ( fear, anger etc )

CAUSES • The word epilepsy actually denotes idiopathic

nature of the problem • The diagnosis requires that the seizures

occurs spontaneously• Nevertheless, certain epileptic syndromes

require particular precipitants or triggers; these are termed reflex epilepsy– Patients with primary reading epilepsy have

their seizures triggered by reading– Photosensitive epilepsy is limited to seizures

triggered by flashing lights.

CAUSES – Children with childhood absence seizures may

be susceptible to hyperventilation

• Other precipitants can facilitate rather than obligately trigger seizures in susceptible individuals

• Emotional stress • Sleep deprivation• Sleep itself• Heat stress• Alcohol• Fever as in febrile convulsions

CAUSES • The influence of various precipitants varies

with the epileptic syndrome• In different age groups some causes are

common– Neonatal age• HIE ( Hypoxic ischaemic encephalopathy )• CNS infections• Trauma• Congenital abnormalities• Metabolic disorders

CAUSES – Infancy and early childhood• Febrile convulsion

– Childhood• Well defined epilepsy syndromes

– Adolescents and adulthood• CNS lesions• Stress • Trauma• CNS infections• Brain tumours• Illicit drug use

PATHOPHYSIOLOGY• Seizures are paroxysmal manifestation of

electrical properties of the cerebral cortex• A seizure results when a sudden imbalance

occurs between the excitatory and inhibitory forces within the network of cortical neurons in favour of a sudden onset net excitation.

• Depending on the affected cortical network the manifestation will differ if it is the visual cortex, the clinical manifestation are visual. Other areas may give rise to sensory, gastatory or motor manifestations.

INVESTIGATIONS• FBC• MPS• LP• Blood culture• EEG may tell seizure type• Neuroimaging; these may provide evidence

about structural abnormalities that could be the cause for the seizures– CT scan– MRI

TREATMENTIndications for starting treatment include

A patient with more than one seizure episodeThe older indication was 2 episodes in 6

months or 3 episodes in a yearThis is taken in conjunction with abnormal

results like abnormal EEG, MRI or CT scanIndications also reflect seizure type as complex

seizures require treatment

DRUGSBlockers of repetitive activation of sodium

channelsPhenytoinCarbamazepineOxcarbamazepineLamotrigineTopiramate

Enhancer of slow activation of sodium channels

DRUGSLacosamideRufinamide

GABA – A receptor enhancersPhenobarbitalBenzodiazepines

Glutamate modulatorsTopiramateLamotrigineFelbamate

DRUGST. Calcium Channel blockers

EthusuximideValproate

N- and L- Calcium channel blockersLamotrigineTopiramateZonisamideValproate

DRUGSH. Current modulators

GabapntinLamotrigine

Blockers of unique binding sitesGabapentinLenetiracetin

Carbonic anhydrase inhibitorsTopiramateZonisamide

Indication for discontinuing treatmentSeizure free for 2 – 5 yearsOver 30% of patients with epilepsy do not

have seizure control even with the best medications

Other treatment modalitiesSurgery

Palliative: Anterior callostomy which is rarely done now. Used for intractable atonic seizures

Curative Lobectomy Lesionectomy

DietKetogenic diet has been effective in improving

seizure control in selected patients

Other treatment modalitiesElectrical stimulation; one approved method

is the vagus nerve stimulation ( VNS )Stem cell transplantation

PROGNOSISThe patient prognosis for disability and for

recurrence of epileptic seizures depends on the type of seizure and the epileptic syndrome in question.

Prognosis is worse with partial seizuresPrognosis is worse with frequent seizures

before presentation

FEBRILE CONVULSIONSDefinition: Convulsion with fever in children

aged 6 months to 5 years whose cause is of an extra cranial origin. Usually lasts 15minutes or less.

About 4% of people will have one seizure episode in their life time

CLASSIFICATIONSimpleComplex

CAUSESAny condition that causes a rapid increase in

temperatureAOMMalariaMeaslesBronchopneumoniaPost immunisation

DIFFERENTIAL DIAGNOSISMeningitisEncephalitisCerebral malariaMetabolic problems

HypoglycemiaHypocalcaemia

INVVESTIGATIONSFBCMPBlood cultureViral serologyLPRBS Serum calcium

TREATMENTControl seizureTreat cause Long term seizure control

STATUS EPILEPTICUSA life threatening condition in which the

brain is in a state of persistent seizuresDefined as one continuous seizure lasting

more than 30minutes or recurring seizures lasting more than 30 minutes without regaining consciousness in between.

Mortality is in the upward of 20% if not treated early

STATUS EPILEPTICUSWith optimal neurologic care a good

prognosis is expected

TREATMENTMake sure patient is breathingClear airway by suctioning if need beDrugs

Diazepam given intravenously its effect lasts 5 – 15 minutes may need to be repeated ( though its half life is 30 hours )

Lorazepam when available lasts longer.

TREATMENTPhenytoin or fosphenytoin: takes 15 – 30

minutes to act so could be administered together with diazepam

Sodium valproate may also be used intravenously

Phenobarbitone or barbiturates

TREATMENTPractice here

DiazepamPhenobarbitoneLargactil

When all failAnaesthesia with patient paralysis and

ventilation