Epilepsy and EEG Flashcards
Criteria for epilepsy
- Two unprovoked seizures > 24hrs apart
- 1 unprovoked seizure with the probability of further seizures
- Two seizures in a setting of reflex epilepsy
Which cells are involved in the origin of seizure activity
Pyramidal Cells
Definition of seizure
Paroxysmal transient occurrence of signs and symptoms due to abnormal excessive or synchronous neuronal activity in the brain
What is the definition of epilepsy?
A disorder of the brain where there is a predisposition to generate epileptic seizures leading to neurobiological, cognitive and psychological/social consequences of the disorder
What is a generalized seizure?
A seizure originating within and rapidly involving bilaterally distributed networks (cortical/subcortical) that can be asymmetrical
What is a focal seizure?
Originating from a discrete location within one hemisphere; may spread to contralateral hemisphere
Best test for evaluating and diagnosing epilepsy
EEG
Benefits of EEG
- Distinguish generalized and focal epilepsy
- Distinguish epilepsy and non-epileptiform events
- Can r/o subclinical seizures causing AMS in ill patients
- Diagnosing hypoxic/anoxic brain injuries, herpes encephalitis
Minimum criterion for a useful EEG
45mins and asleep
Factors which increase the yield of the EEG
- Within 24-48hrs of seizure
- Done w/ sleep deprivation
- Recorded sleep state
When to consider Tx after a single seizure
If epileptiform activity is seen on the EEG
What are landmarks used to place the EEG leads?
- Nasion
- Inion (occipital protuberance)
- Zygoma
- Tragus
- Preauricular Point
What are the types of EEG waves and their respective frequencies?
Alpha 8-13Hz
Beta 13-30Hz
Theta 4-8Hz
Delta 1-4Hz
What is the T6 Spike?
An intra-ictal event which shows up as a sharp peak between episodes
What is a focal seizure without loss of consciousness?
Simple Partial
What is a focal seizure with a loss of consciousness/dyscognitive?
Complex Partial
What is a focal seizure that evolves to result in bilateral convulsions?
Partial Seizure with secondary generalization
What term denotes a focal seizure?
Partial
Which term denotes no loss of consciousness?
Simple
Which term denotes loss of consciousness?
Complex
What are different types of generalized-onset seizures?
- Absence
- Myoclonic
- Tonic-Clonic
- Atonic
What is the typical EEG finding of an Absence Seizure?
3Hz Spike and Wave
What are the possible etiologies of epilepsy?
- Genetic
- Structural/Metabolic
- Idiopathic
- Immune Mediated Inflammatory Process
What are some examples of genetic causes of epilepsy?
Channelopathies (Dravet Syndrome, AD Nocturnal Frontal Lobe Epilepsy)
What are some structural causes of epilepsy?
- CVA
- Tumor
- Trauma
- AV Malformation
- Infection/Abscess
What are some metabolic causes of epilepsy?
- Hypernatremia
2. DKA
What is a possible cause of seizures in the neonate?
Benign Familial Neonatal Epilepsy
What are possible causes of epilepsy in infancy?
- West Syndrome
2. Dravet Syndrome