Epilepsy Flashcards
Define epilepsy
- This is a recurrent tendency to spontaneous, intermittent abnormal electrical activity, manifesting as seizures
- It is a group of many different ‘epilepsies’ with one thing in common - a tendency to have seizures that start in the brain
Define a seizure
This is abnormal discharge of electrical activity in the brain causing alterations in behaviour, sensation or convulsions
- In most brains, neuron interactions occur in a chaotic but balanced, orderly fashion with few disruptions. Occasionally small disruptions (neuron misfires) may occur with little consequence
- When multiple cells misfire at the same time, depending on the severity & location in the brain this may cause a seizure
Are all seizures due to epilepsy ?
No!
- Other conditions that can look like epilepsy include fainting, hypoglycaemia in diabetes or a change in the way the heart is working, febrile convulsions
- These are all not epileptic seizures and the cause of them does not start in the brain
- 2.5% of the population affected by seizures but ony 0.5% are affected by epilepsy
When are CT scans indicated in someone presenting with a seizure ?
- Any new seizure
- Focal seizures
- Significant post-ictal focal deficit
- Epilepsy presenting as status epilepticus
- Associated preceding persistent headache of recent onset
- Seizure frequency accelerating over weeks or months
In general when can epilepsy only be diagnosed after ?
Once they have had >1 seizure as it is a continuing tendency to have seizures
What is there a rare risk of for 1 in 1000 people with epilepsy ?
Rare risk of sudden death (SUDEP)
Do all epileptic seizures involve convulsions ?
No some people can seem vacant, wander or are confused when a seizure is occurring
Are all people aware they are going to have a seizure ?
No - some people are aware of the beginning of a seizure hrs to days before it happens. On the other hand some may not be aware of the beginning & ==> have no warning
Describe the prodome in relation to a seizure
Some patients may notice a change in mood or behaviour, this may warn a patient a seizure may come. It is not part of the seziure & not everyone gets it
Describe an aura in relation to a seizure and the type of seizure it may hint towards
- This is part of the seizure itself & may preceed the other manifestations of a seizure. The aura may be a strange feeling in the gut, deja vu, strange smells or flashing lights
- It implies a partial (focal) seizure often but not alway, from the temporal lobe
What is the ictal-phase of a seizure ?
This is the period of time from first symptoms to the end of seizure activity
Describe the post-ictal phase after a seizure
This is where there may be any of the symptoms of; headache, confusion, myalgia or a sore tongue, or temporary weakness after a focal seizure in the motor cortex or dysphagia from a seizure afecting the temporal lobe
What are the causes of epileptic seizures ?
- 2/3rds are idiopathic (often familial)
- Cortical scarring e.g. from head injury years before onset of seizures
- Structural change in the brain such as the brain not developing properly
- Damage caused by brain injury, infections such as meningitis, a stroke or a tumour
- Structural changes such as tuberous sclerosis, or neurofibromatosis (type 1), which can cause growths affecting the brain
What are the non-epileptic causes of seizures ?
- Trauma
- Stroke
- Haemorrhage
- Raised ICP
- Alcohol or benzodiazepine withdrawal
- Metabolic disturbances (increased or decreased Na+, decreased Ca2+, increased or decreased glucose etc)
- Liver disease
- Infections e.g. meningitis, syphilis, HIV
- Increased temp (febrile convulsions main one)
- Drugs e.g. tricyclics, cocaine, tramadol etc
- Pseudoseizures (non-epileptic attack disorder)
How is epilepsy diagnosed ?
1st take a detailed history from the patient & an eyewitness to the attack to determine whether or not an epiletic seizure if likely to have occurred
If diagnosis cannot be established via history then further investigations are done
If diagnosis of epilepsy cannot be established via history then what further investigations are done to try and establish a diagnosis of epilepsy ?
- Blood tests for - Us and Es, glucose, calcium should be done
- 12 lead ECG should be performed in suspected epilepsy
- EEG may be used
- Imaging may be used - MRI best
When should EEG be used in the diagnosis of epilepsy ?
- It should be used only to support a diagnosis of epilepsy in whom clinical history suggests that a seizure is likely to be epileptic in origin, it should be performed after the 2nd epileptic seizure not the 1st
- It may also be used to help determine the seziure type & epilepsy syndrome, also to assess the risk of seizure recurrence
When should brain imaging be used in diagnosis of epilepsy ?
It should not be used routinely when a diagnosis of idiopathic generalised epilepsy has been made
It should be used to identify structural abnormalities that cause certain epilepsies - MRI is imaging of choice, CT may be used actuely
MRI is particularly important in those who:
- Develop epilepsy <2yrs old or in adulthood
- Who have symptoms of a focal seizure
- In whom seizures continue despite 1st line medication
What are the indications for EEG in epilepsy ?
- Classification of epilepsy
- Cinformation of non-epileptic attacks (EEG will be normal in these patients)
- Surgical evaluation
- Confirmation of non-convulsive status epilepticus = which is persistent (>30min) change in behaviour &/or mental processes from baseline associated with continuous epileptiform EEG changes but without major motor signs
Is examination of a patient usually done with suspected epilepsy ?
- No as it has little/ no benefit
- However if a diagnosis of syncope likely then CV examination, BP etc is important to carry out
What are the common differential diagnosis that could present like epilepsy ?
- Syncope
- Non-epileptic attack disorder
- Panic attacks/ hyperventilation attacks
- Sleep phenomena
