Epilepsy Flashcards
(50 cards)
Seizure
-episode of abnormally synchronized & high frequency firing of neurons resulting in abnormal behavior or experience
Epilepsy
-chronic brain disorder of various etiologies characterized by recurrent, unprovoked seizures
Epilepsy Syndromes
-grouping of similar epileptic patients according to seizure type, EEG age of onset, prognosis & clinical signs
Epidemiology of Epileptic Seizures
- 0.5% of pop.
- 2.5 million prevalent cases
- 150,000 to 200,000 new cases/year
- age-specific incidence had dec. in younger age groups, inc. in patients over age 60
Causes of Adult-onset Epileptic Seizures
- Cerebrovascular disease
- Trauma
- Tumors
- Infections
- Cerebral Degeneration
ILAE Classifications of Epileptic Seizures
-Clinical Observation + EEG FIndings
partial seizures and generalized seizures
Types of Partial Seizure
- Simple (consciousness preserved)
- Complex (consciousness impaired)
- Secondarily Generalized (consciousness lost + bilateral cerebral involvement)
Simple Partial Seizures
- Signs/symptoms depend on focus: motor (Jacksonian - move up body part), somatosensory, autonomic, psychic
- consciousness is intact
- EEG may appear normal
- Auras are brief, simple partial seizures with no overt behavioral manifestations
Complex Partial Seizures
- impaired consciousness
- lasts ~1min
- blank stare
- oral/ipsilateral hand automatisms
- contralateral dystonic posturing
- amnesia for ictal event
- focal abnormality on routine EEG
Primary Generalized Seizures
- absent (Petit Mal)
- tonic-clonic
- clonic
- tonic
- myoclonic
- atonic
Absence Seizure Features
- brief loss of consciousness (10-20sec)
- staring spell
- no post-ictal confusion
- subtle myoclonic movement, eyelid flutter
- no baseline neurologic deficits
- baseline EEG may show generalized 3Hz spike -wave discharges
Tonic-Clonic Seizures
-typical presentation:
cry, loss of consciousness, muscular rigidity (tonic), patient may fall, rhythmic jerking (clonic), tongue-biting/injury common, bladder/bowel incontinence, post-ictal confusion/sleep
-Grand Mal
Myoclonic Seizure
-brief, shock-like muscle contractions (head, upper extremities)
-usually bilaterally symmetrical
-consciousness preserved
-precipitated by awakening or falling asleep
-may progress into tonic-clonic seizures
(juvenile myoclonic epilepsy)
Atonic Seizure
- impaired consciousness
- loss of muscle tone
- head drop, fall
- brief duration (few seconds)
- injury common
Seizure Diagnosis
- History from patient & witnesses
- Physical & neurological examination
- CBC, CMP, AED levels
- Inter-ictal EEG
- Epilepsy protocol MRI
- Video-EEG monitoring
Prevalence of Inter-ictal Epileptiform Discharges in Epileptic Patients
- initial EEG detects on epileptiform discharge in 29-55% of patients
- serial EEGs reveal epileptiform discharges in 80-90% of patients
- Repeat studies, with sleep deprivation & extended recording times, helps inc. chances of detecting epileptiform discharges in patients with epilepsy
Focal Epileptiform Discharge
- seizure focus is in left anterior temporal head region
- sharp waves, spikes, & sharp-and slow wave discharges
Generalized Epileptiform Discharge
- bilateral burst of epileptiform spike & slow wave discharges
- discharge simultaneously & symmetrically in both hemispheres
Seizure MRI
-Recent-onset epilepsy in adults requires imaging sequences, including gadolinium-DPTA enhanced sequences to find primary or secondary tumors, infection or inflammation
Epilepsy Protocol MRI
- Coronal high resolution T1-weighted volume data set through the whole brain
- a coronal T2-weighted sequence, typically using 3 mm thin sections, should also be done in order to detect hippocampal sclerosis
Video-EEG monitoring
- simultaneous recording of EEG & seizure
- useful in differentiating epileptic seizures from non-epileptic seizures
- useful for characterizing seizure type
- essential for pre-surgical localization of the seizure focus
Pathophysiology of Seizures
- Ligand-gated ion channels can be excitatory or inhibitory depending on their ion selectivity
- GABA activates GABA a receptors that mediate fast synaptic inhibition (IPSP) by permitting rapid influx of Cl ions, resulting in hyperpolarization
- glutamate activated 3 classes of ion channels (AMPA, Kainate, NMDA) that mediate fast synaptic excitation by permitting a rapid influx of NA and Ca ions
- in most neuronal circuits, GABAergic inhibition exerts a powerful suppression of excitability
- this inhibition is overcome during the development of a focal seizure
Goal of Antiepileptic Drug (AED) Therapy
-2 types of remission:
Medical remission: seizure free without side effects on 1 or 2 AEDs
-Disease Remission: seizure free off all AEDs
-major goal of AED therapy is to achieve medical remission
-surgical therapy is well-selected cases may result in disease remission
AED Selection
- efficacy for specific seizure types or epilepsy syndrome
- efficacy for co-morbid conditions
- interactions with other drugs
- ease of introduction, follow-ip
- drug safety
- cost
