Epilepsy
Epilepsy describes the
tendency to suffer from a paroxysmal discharge of cerebral neurones resulting
in a convulsion
Incidence
3% of the population have 2
or more seizures during their lives
250 000 people in the
Seems to be twice as common
in
Pathophysiology
Normally the spread of
electrical impulses in the CNS is restricted.
Only small groups are
synchronised at any time giving rise to normal EEG rhythms.
During a convulsion large
groups of neurones are activated repeatedly hypersynchronously.
Failure of
the action of inhibitory synapses.
High voltage spike and wave
activity is seen on the EEG.
Seizure threshold
Clinical Types
Epilepsy may be generalised
or focal
Generalised seizures
Grand mal
Most common form of epilepsy
Aura - tonic - clonic - coma
Self injury
Incontinence
Status may occur
Petit mal
Typical absences
Mostly children
3 Hz spike and wave
Activity ceases, the child
stares, pales slightly, eyelids may twitch, a few
jerks may occur.
Duration of a few seconds
After the attack the child
carries on as if nothing has happened
Never due to identifiable
local lesions
Children may go on to develop
generalised seizures in adult life
Focal seizures
Discharge from a focal group
of neurones
Clinical features provide
evidence of origin
Different types occur
Jacksonian fits
Localised fitting starting in
the motor cortex
Spread occurs into the
opposite side of the body, this is "the march" of the seizure
Paralysis of the effective
limb may occur for some hours after, (Todd`s paralysis)
Temporal lobe fits
Partial seizures often
associated with jamais vu and deja vu.
Visual hallucinations may
occur
There may be secondary
generalisation of a partial seizure
Aetiology
Primary or secondary
Found in 25% of cases
Precipitating factors include
Family history, (about 30%
have affected first degree relatives)
Trauma and surgery
SOL
Cerebral infarct
Drugs alcohol and withdrawal
Encephalitis
Metabolic abnormality
Degenerative brain disorders
Photosensitivity and auditory
stimuli
Febrile convulsions - pyrexia
under the age of 5 years
Investigations
EEG EEG
telemetry CXR Blood biochemistry CT/MRI
Treatment
Prevent harm to the patient
Long term anticonvulsant
therapy
Phenytoin, Carbamazapine,
Sodium Valpoate
Surgery
Status epilepticus
One fit after another without
recovery of consciousness
A medical emergency - death
may occur from cardiorespiratory failure
IV diazepam, bolus and
infusion, may also be given PR
Chlormethiazole IVI
Phenytoin, phenobarbitone
Neurosurgical
Driving
No fits for the past two
years
Any attack after the age of 3
years bans HGV and PSV for life