Epilepsy Flashcards
What is epilepsy?
Epilepsy is a recurrent tendency to spontaneous, intermittent, abnormal electrical activity in the brain, manifesting as seizures.
Convulsions are the motor signs of electrical discharge.
What are the elements of an epileptic seizure?
Some patients may experience a preceding prodrome lasting hours or days in which there may be a change in mood or behaviour.
An aura implies a focal seizure, often from the temporal lobe.
It may be a strange feeling in the gut, an experience such as deja vu, or stage smells or flashing lights.
Post-ictally, there may be a headache, confusion, and myalgia, or temporary weakness after a focal seizure in the motor cortex, or dysphasia following a focal seizure in the temporal lobe.
What are the causes of epilepsy?
2/3 are idiopathic.
Structural: cortical scarring (e.g. head injury years before onset), developmental (e.g. dysembryoplastic neuroepithelial tumour or cortical dysgenesis), space-occupying lesion, stroke, hippocampal sclerosis (e.g. after a febrile convulsion), vascular malformations.
Others: tuberous sclerosis, sarcoidosis, SLE, PAN, antibodies to voltage-gated potassium channels.
How is epilepsy diagnosed?
Can be difficult due to heterogenous nature of the disease (there are >40 different types of epilepsy).
NICE estimate 5-30% of people with ‘epilepsy’ have been wrongly diagnosed.
All patients with a seizure must be referred for specialist assessment and investigation in <2 weeks.
Take a thorough history: including a detailed description from a witness, ask specifically about tongue-biting and a slow recovery; if this is a first seizure, ask about past funny turns/odd behaviour; deja vu and odd episodic feelings of fear may be relevant; are there any triggers (e.g. alcohol, stress, flickering lights/TV)? triggered attacks tend to recur.
Establish the type of seizure.
Rule out provoking causes: trauma, stroke, haemorrhage, raised intracranial pressure, alcohol or benzodiazepine withdrawal, metabolic disturbance, infection, pyrexia, drugs.
How is epilepsy investigated?
Look for provoking causes.
Consider an EEG: it cannot exclude epilepsy and can be falsely positive- don’t do if syncope likely diagnosis.
Only do emergency EEG if non-convulsive status is the problem.
MRI (structural lesions), drug levels (if on anti-epileptics- is the patient compliant?), drugs screen, LP (e.g. if infection suspected).
Seizure classification: What are generalised seizures?
Originating at some point within, and rapidly engaging bilaterally distributed networks leading to simultaneous onset of widespread electrical discharge with no localising features referable to a single hemisphere.
Important subtypes: absence, tonic-clonic, myoclonic, atonic (akinetic), infantile spasms.
Seizure classification: What is an absence seizure?
Brief (≤10s) pauses, e.g. suddenly stops talking in mid-sentence, then carries on where left off.
Presents in childhood.
Seizure classification: What is a tonic-clonic seizure?
Loss of consciousness.
Limbs stiffen (tonic), then jerk (clonic).
May have one without the other.
Post-ictal confusion and drowsiness.
Seizure classification: What is a myoclonic seizure?
Sudden jerk of a limb, face, or trunk.
The patient may be thrown suddenly to the ground, or have a violently disobedient limb.
Seizure classification: What is an atonic (akinetic) seizure?
Sudden loss of muscle tone causing a fall.
No LOC.
Seizure classification: What are infantile spasms?
Commonly associated with tuberous sclerosis.
Seizure classification: focal seizures evolving to a bilateral convulsive seizure
‘Secondary generalised’.
In 2/3 of patients with partial seizures, the electrical disturbance which starts focally spreads widely, causing a generalised seizure, which is typically convulsive.
Localising features of focal seizures: temporal lobe
Automatisms- complex motor phenomena with impaired awareness, varying from primitive oral (lip smacking, chewing, swallowing) or manual movements (fumbling, fiddling, grabbing), to complex actions.
Dysphasia.
Deja vu (strangely familiar) or jamais vu (everything strangely unfamiliar).
Emotional disturbance, e.g. sudden terror, panic, anger, or elation, and derealisation (out of body experience).
Hallucinations of smell, taste, or sound.
Delusional behaviour.
Bizarre associations.
Localising features of focal seizures: frontal lobe
Motor features such as posturing or peddling movements of the legs.
Jacksonian march (spreading focal motor seizure with retained awareness, often starting with the face or thumb).
Motor arrest.
Subtle behavioural disturbances (diagnosed psychogenic).
Dysphasia or speech arrest.
Post-ictal Todd’s palsy (temporary weakness after focal seizure in motor cortex).
Localising features of focal seizures: parietal lobe
Sensory disturbances: tingling, numbness, pain (rare). Motor symptoms (due to spread to pre-central gyrus).
