Epilepsy Flashcards
What is the definition of syncope?
Transient loss of consciousness due to hypoperfusion of the brain
What is the definition of seizure?
The clinical manifestation of abnormal synchronised neuronal discharge
What is the definition of epilepsy?
A tendency to have recurrent unprovoked seizures; typically diagnosed after 2 or more recurrent seizures
Describe a typical history of generalised seizure
Situation -Alcohol excess, sleep deprivation Trigger -Flashing lights, driving past railings Warning -None, or any number of auras Aftermath -Prolonged confusion, waking with paramedics present, lateral tongue biting, possible injury Witness -Initial cry, limbs stiffened, continuous rhythmical convulsions, central cyanosis, abnormal noisy breathing Presdisposition -Head injury, febrile seizures, meningitis, family history of seizures
What is a partial seizure?
An epileptic seizure where the epileptic network is confined to one cerebral hemisphere only This must be caused by a focal brain abnormality, that MAY OR MAY NOT be visible on an MRI scan
What is a generalised seizure?
An epileptic seizure where the epileptic network involves both cerebral hemispheres
What is a simple partial seizure?
A partial seizure with unimpaired awareness AKA aura
What is a complex partial seizure?
A partial seizure with impairment or absence of awareness. This may mean the patient just stares blankly or they may have automatisms
What is a secondarily generalised seizure?
When the epileptic network in a partial seizure spreads to the opposite hemisphere and so becomes generalised
What is an automatism?
Coordinated involuntary simple movements or more complex acts performed by a person who is unaware of them, because consciousness is sufficiently impaired eg. oro-alimentary (lip-smacking), gestural
What are the characteristics of a medial temporal lobe seizure (most common)?
- Epigastric rising sensation (butterflies) - Fear/panic - Olfactory hallucincations - Deja-vu - Impaired awareness and automatisms - Pale, pupil dilation (autonomic) NB this is where the hippocampus lies
Seizures from which lobe typically cause a jacksonian march?
Frontal
What is a common cause of medial temporal lobe epilepsy?
Hippocampal sclerosis
What is idiopathic generalised epilepsy?
A group of primary generalised seizures which occur in a cohort with structurally normal brains (thought to be genetic) Makes up 1/3 of cases of epilepsy
When is the typical onset of IGE?
Childhood/adolescence
Can partial epilepsy be photosensitive?
NO
Describe a typical generalised tonic clonic seizure
May start with a groan / cry Patient stiffens and falls (tonic phase) Limbs may adopt abnormal posture Sometimes cyanosed Synchronous, continual shaking of all limbs (clonic phase) Very drowsy afterwards (unable to speak coherently or recognise family) May be incontinent May bite the side of the tongue First memory is often being in presence of paramedics
How do generalised tonic clonic seizures arise?
The majority are idiopathic primary generalised seizures, but some can be secondary generalised from a focal onset.
What is an absence seizure?
A seizure occurring in patients with IGE that involves a lack of awareness, automatisms and autonomic components, lasting a few seconds.
How can you distinguish between an absence seizure and a complex partial seizure?
ABSENCE - generalised onset, childhood, no warning or post-ictal phase, may be photosensitive, <10secs COMPLEX PARTIAL - focal onset, any age, aura warning and post-ictal phase, lasts at least 30 secs, not photosensitive
What is a myoclonic seizure?
A seizure occurring in patients with IGE, involving a sudden shock like movement, often early in the morning.
What is NEAD?
Non-epileptic attack disorder aka dissociative/functional seizures These are episodes of limb-shaking, in the absence of epileptic neuronal activity
What are the characteristics of a NEAD attack?
- Limbs flailing - Asynchronous limb convulsions - Head shaking - Pelvic thrusting - Repetitive groaning - Sobbing - Normal/rapid breathing - Forced eyelid closure NB any display of emotion in a seizure makes it very unlikely to be epilepsy
What are the red flags for NEAD?
- Psychiatric history - Learning disability - Medically unexplained symptoms - No post-ictal phase - Emotional - Awareness - All limbs shaking - Explosive onset - Seizures lasting over 10 mins
Describe the epidemiology of epilepsy
47 per 100000
If a patient has suspected epilepsy, what imaging should be done?
CT head scan - excludes obvious brain lesion, not helpful for focal neurology MRI
What tests should be done in a patient with suspected epilepsy?
Bedside - Obs, ECG (check for severe cardiac syncope) Bloods - FBC, U&E (check general health) Imaging - CT, MRI Special Tests - EEG
What abnormalities can be seen on an ECG to provoke a seizure?
- Heart block - Previous MI - Prolonged QT interval (ventricular tachycardia)
What features of an EEG can provide evidence for epilepsy?
Look for INTERICTAL EPILEPTIC DISCHARGES (spikes or sharp waves superimposed on the background rhythms)
How can we increase EEG sensitivity?
Sleep deprivation greatly increases the incidence of IEDs
What is the point of doing an EEG?
- Determine whether seizure is focal or generalised - Determine seizure recurrence risk - Captures a non-epileptic attack
What are the principles of treating epilepsy?
Treat after 2 unprovoked seizures. Use one agent and increase dose after every subsequent seizure until; - Seizure free - Maximum dose reached - Intolerable side effects occur If seizures persist, a second drug is added in the same way, then the least effective drug is withdrawn
What are the principles of letting people with epilepsy drive?
Have to be seizure free for 6 months with normal EEG, normal MRI and nothing to suggest risk of recurrence
What drug is first line for generalised epilepsy?
Men: Sodium Valproate Women: Lamotrigine (less teratogenic)
What drug is first line for focal epilepsy?
Carbamazepine and Lamotrigine (better tolerated)
Which members of the MDT are involved in the care of a patient with epilepsy?
Epileptologists, neurosurgeons, nurses, EEG technicians, psychiatrists, social workers, DVLA, pharmacologists
What drug is first line for generalised absence seizures?
Ethosuximide
What are the side effects of sodium valproate?
Weight gain Tremor Parkinsonism Teratogenicity
What are the size effects of carbamazepine, phenytoin and lamotrigine?
Tiredness, double vision, steadiness, RASH
What are the side effects of topiramate?
Weight loss, behavioural changes, paraesthesia, kidney stones
What are the side effects of levetiracetam?
Tiredness, dizziness, aggresion
Which AEDs are enzyme inducers of the OCP?
Carbamazepine (anything -epine) Phennytoin Topiramate
Which AEDs are metabolised by the liver?
If in doubt, CP450
What are the indications for monitoring AEDs?
- As guide to dosing - To check compliance - Toxic symptoms - To monitor interactions - During pregnancy - Learning disabilities
How is status epilepticus treated?
ABCDE Hospital - IV lorazepam GP - rectal diazepam Kids - buccal midazelam If these fail, give phenytoin, phenobarbital or transfer to ITU
Why do you sometimes get: a) raised GGT b) hyponatremia when being treated with carbamazepine, and what is the consequence?
a) this is because carbamazepine is an enzyme induce, you can continue with treatment but monitor b) as a consequence of SIADH - if symptomatic should discontinue treatment
Why does carbamazepine require dose adjustment as you continue treatment?
It is an AUTO-INDUCER - as treatment goes on it induces its own metabolism, so you will need to increase the dose
What are the symptoms of carbamazepine toxicity?
Nystagmus Ataxia Increased seizure frequency THESE ARE DUE TO CEREBELLAR TOXICITY
