Physiology Epilepsy Flashcards
What is a seizure?
A convulsion or transient abnormal event resulting from a paroxysmal discharge of cerebral neurons
What is epilepsy?
The continuing tendency to have a seizure
List the criteria needed to diagnose a seizure.
1 - at least two unprovoked seizures occurring more than 24 hours apart
2 - one unprovoked seizure and a probability of further seizures similar to the general recurrence risk after two unprovoked seizures (approx. 75% or more)
3 - at least two seizures in a setting of reflex epilepsy
List the criteria to think about when looking at seizure types.
Focal/Generalized/Unknown Onset (area affected)
Level of consciousness
Motor or not
Clonic
Shaking/jerking movements
Tonic
Being stiff
*Automatisms
Automatic behaviours
*Emotions
Emotions or appearance of emotions
- Tonic
Extension or flexion postures
*Autonomic
Flushing/sweating/piloerection
*Myoclonous
Jerking arrhythmically
*Clonus
Jerking rhythmically
*Cognitive
Language or thinking problems, deja vu
*Eyelid myoclonia
Lid jerks
*Atonic
Limp
*Sensations
Numb/tingling, sounds, smell, tastes, visions, vertigo
*Behaviour arrest
Pausing, freezing, activity arrest
*Hyperkinetic
Thrasing/pedaling
*Spasm
Trunk flexion
Why is the level of consciousness a key role in seizures?
Importance for driving, safety during seizures, employability, interference with schooling and learning
Name some evidence helpful in classifying seizures.
Videos brought in by family
EEG patterns
Lesions detected by neuroimaging
Lab results e.g. detection of anti-neuronal antibodies
Gene mutations
Diagnosis of an epilepsy syndrome diagnosis
Describe the EEG of a generalized seizure.
Sudden onset
All leads/cords have same start and pattern
Describe the EEG of a partial/focal seizure.
Only some of the leads show disruption
Starts in one place and spreads to become more general
List some differential diagnoses of seizures.
Syncope Migraine TIA Hypoglycaemia Panic attacks Breath holding attacks Psychogenic non-epileptic seizures
Describe some characteristics of non-epileptic seizures.
Gradual onset Eye closure Asymmetrical thrashing movements Side to side head movements Pelvic thrusting Lack of stereotypic pattern Talking or screaming Long duration Sudden return to consciousness Waxing and waning
What causes seizures?
Genetic predisposition
Developmental e.g. neuronal migration abnormalities
Trauma and surgery
Pyrexia (fever)
Intracranial mass lesions: tumour
Vascular: cerebral infarction, arteriovenous malformation
Drugs and drug withdrawal
Encephalitis and inflammatory conditions
Metabolic abnormalities e.g. hypocalcaemia
Neural degenerative disorders
Provoked seizures: photosensitivity and sleep deprivation
What investigations do you need to perform for seizures?
Blood tests: FBC, urea and electrolytes, calcium, glucose, CRP, toxin screen
Xray chest (mass in chest metastasized to head)
ECG
EEG
Neuroimaging: CT or MRI
Lumbar puncture if CNS infection a possibility
When do you start treatment for seizures?
2 or more seizures
Single seizure if risk factors (structural lesion, EEG abnormality, partial seizure, family history of seizures)
Immediate treatment increases time to a second seizure and reduces the time to 2 year remission
When do you stop treatment?
Consider after 2 years
Do gradually
What is status epilepticus?
If seizures recur without recovery or a single seizure continues >5min, treat as status elipticus
List examples of epilepsy surgery.
Focal resections Hemispherectomy Large multilobar resections Corpus callostomy Vagal nerve stimulation
Name the drugs for Step 1 (5-20min) of status epilepticus.
Lorazepam: 0.1mg/kg up to 4mg IV bolus
or
Diazepam: 0.15 - 0.2mg/kg up to 10mg at 2mg/min
(the above two drugs need to be repeated once every 5-10min if necessary)
or
Midazolam 10mg IV, intramuscular, intranasal or buccal = best option if no immediate IV access
Name the drugs used for status epilepticus (step 2: 20-40min)
Sodium valproate
Phenytoin
Levetiracetam
Name the drugs involved in step 3 (40-60min) of status epilepticus.
Induce a drug-induced coma in ICU:
Midazolam
or
Propofol
Monitor EEG to maintain burst suppression pattern