Seizures Patho Flashcards
Definition
Seizures
- burst of electrical activity
- neurons are hyper excitable (lower seizure threshold)
- increased freuqency and synchronicity of discharge
Provoked Seizure
Etiology & Treatment
Seizure is secondary to a known cause
*This is NOT epilepsy
Treatment: Treat cause
- Drugs and drug withdrawal
- CNS Depressants: Alcohol, barbiturates, benzodiazepine withdrawal
- CNS stimulants: Cocaine, amphetamines - Infection
- meningitis - Cerebrovascular event and diseases
- hemorrhage, stroke, ischemia, AVM
- multiple scelerosis - Traumatic brain injury
- Metabolic disorders
- Hyperaemia
- hypoglycemia
- electrolyte imbalances
- Acid-base imbalances
- Dehydration - Idiopathic
Two types of Seizures
- Unprovoked (primary, epilepsy)
- Provoked (secondary)
Epilepsy
Diagnostic Definition
- Two unprovoked seizures within 24 hours
- 1 unprovoked seizure with > 60% re-occurance rate in 10 years
- epilepsy syndrome
Epileptogenic Focus
Pathophysiology
Group of hyper-excitable neurons
Depolarization shift, lower threshold for action Potential generation
Fire
1. more frequently
2. greater amplitude
Cortical excitation and spreading
-neighbour neurons recruited
- fire more easily
- seizure generalizes
Brain Regions
Tonic vs. Clonic
Tonic: Muscles rigid
Brain: brainstem, sub cortex, thalamus
Clonic: rhythmic contract-relaxation
Brain: basal ganglia, thalamus, cortex
Seizures
Oxygen Consumption
Seizures = increased BMR
- increase oxygen demand
- increase cerebral blood flow
- increase glucose consumption
Status
Risk: anaerobic glycolysis, acidosis, brain damage
Seizures
Mirror Focus
Mirror focus
- contralateral side of brain
- mirror epileptogenic focus
- learns to seize
Focal Seizure
- Discrete area of brain
- One hemisphere
- clinical symptoms = brain area activated
Generalized seizure
- primary generalized
- onset generalized
- both hemispheres
- loss of consciousness - secondary generalized
- cortical spreading from focal seizure
- loss of conscousness
- both hemispheres
3 phases of a Seizure
- Pre-ictal
- Ictal
- POst-ictal
Pre-ictal
- Prodrome: HA, tired, depressed, mental clouding (days, hours)
- aura: sensory warning (partial seizure)
Ictal
- Tonic: muscle rigidity (brainstem)
- Clonic: rhythmic relaxation and contraction (basal ganglia)
Post-ictal
- immediately following seizure (hours, days)
- HA, confusion, dysphasia, paralysis (Atodd’s paresis)
- neurons exhausted
Status Epilepticus
Definition
- Seizure duration > 5 minutes
- 3 seizures in 30 minutes
Risk
- mirror focus
- irreversible brain damage: anaerobic glycolysis, acidosis
International League of Epilepsy
Seizure Levels
- Seizure type
- focal
- generalized
- unknown - Epilepsy type (*EEG required)
- focal
- generalized
- combined
- uknonwn - Epilepsy syndrome
ILAE
Focal Seizure
Characterization
- Level of awareness (aware vs. not aware)
- Level of motor involvement ( motor vs. non-motor)
- Level of generalization (focal –> bilateral)
Examples:
Focal, aware, motor involvement
Focal, aware, non-motor involvement
Focal, unaware, motor involvement
Focal, unaware, non-motor involvement
Focal aware seizure
Focal
- discrete area of brain
Aware
- one hemisphere
Also known as “simple partial seizure)
Focal unaware seizure
Focal
- discrete area of brain
- usually starts prodrome: aura (simple partial seizure)
Unaware
- generalized to both hemispheres
Also known as “complex partial seizure”
ILAE
Focal Seizure
Motor Onset
Examples
- Automatism: lip smacking
- Atonic: loss of motor
- Clonic: rhythmic relax-contract
- Spasm: fencing position
- Hyperkinetic: bicycling
- myoclonic: jerk
- tonic: stiff
ILAE
Focal Seizure
Non Motor Onset
Examples
- Autonomic: ANS, SNS ex. flushing
- Behavioural arrests: stop, staring
- cognitive: language deficit
- emotional: fear, laugh, cry
- sensory: gustatory, numbness, tingling
ILAE
Generalized Onset Seizure
Definition
Generalized
- both hemispheres
- loss of consciousness right away (unaware)
Motor vs. Nonmotor
Ex. Absence seizure
Generalized, non-motor, unaware
Sudden cessation of activity
ILAE Generalize Seizure
Nonmotor onset
Nonmotor onset
- typical: sudden stop activity, blank stare
- Ayptical: tone is pronounced
- myoclonic: eyes jerk upwards
ILAE Generalized Seizure
Motor onset
Motor onset
- tonic
- clonic
- myoclonic
- atonic (drop seizures)
- *mixture of the above
Differential Diagnosis
Psychogenic seizure
- Eyes closed
- Asynchronous movements
- bicycling, pelvic thrusting
- can talk
- wax and wane
- 10 to 30 minutes
- history trauma, abuse
Differential diagnosis
Fainting
- Eyes roll back in head
- twitch after they lose consciousness
- pale
- low blood pressure, low heart rate
Diagnostic work up
Seizure
- Seizure onset
- focal? generalized?
- aware? unaware?
- motor? non-motor?
- first time? new? - R/O metabolic causes (ABCDEFG)
- Vital sign extremes
- labs: electrolytes (Na, K, Mg, Ca), acid-base balance, toxicology screen, glucose level
- eclampsia (8 weeks post party) - Labs for seizure complications
- Cardiac: troponin, ECG (MI)
- Metabolic acidosis: lactate, creatinine kinase (rhabdomyolysis)
- hypoglycaemia: glucose
- electrolytes: dehydration - Imaging
- CT (10-15% positive secondary cause) - Loading dose Keppra
1500mg PO
D/C home if stable, someone watching
10% re-occurance within 24 hours
referral neurology
EEG urgent (first time seizure, status, don’t D/C)
