Epilepsy I Flashcards
Differences between seizures and epilepsy
Epilepsy is unprovoked, seizures can be provoked.
Epileptic seizures are spaced out for >24h apart, seizures could occur any time based on medical or extenuating conditions.
At least 2 seizures are required to be considered as epilepsy, the number of seizures for a general seizure does not matter.
Diagnosis of epilepsy syndrome vs none
Epilepsy causes:
- Genetic: fragile chromosome
- Structural: previous brain injury or structural abnormality
- Metabolic: mitochondrial disorder, GLUT1 deficiency
-Immune, infectious (HIV, TB, meningitis)
Seizure causes:
-electrolyte imbalances, toxic substances, brain injury, stroke, CNS infection
Pathophysiology of seizures and epilepsy
A. Hyperexcitability
- imbalances between extracellular and intracellular substances (Na+, K+, Ca2+, Cl-)
- excessive amount of excitatory neurotransmitters, few inhibitory neurotransmitters.
B. Hypersynchronization
- Hyper-excitable neuron will end up excessively exciting the entire group of neurons
Classification of epilepsy
- Focal onset
- Originates from one hemisphere of the brain - Generalized onset
- Originates from both hemispheres of the brain
What is the ILAE 2017 Classification of Seizure Types (Expanded Version)?
- Where seizures begin in the brain
- Level of awareness during the seizure
- Focal: can be aware, or impaired awareness
- Generalized: usually unaware - Other features of the seizure
- Focal (motor onset): automatisms
- Generalized onset (non-motor, absence): eyelid monoclonia
Factors that affect the clinical presentation of the symptoms
- Site of the focus
- Degree of “irritability” of the areas of the brain surrounding the focus
- Intensity of the impulse
Focal onset (without discognitive features) / simple partial
- Motor symptoms
- Clonic movements (e.g. twitching and jerking)
- Speech arrest - Sensory
- Feelings of numbness or tingling
- Visual disturbances
- Rising epigastric sensation - Autonomic symptoms
- Sweating, salivation or pallor
- BP, HR - Psychic (or somatosensory symptoms)
- Flashbacks
- Visual, auditory, olfactory, gustatory hallucinations
- May experience fear
Clinical presentation of focal onset (With Dyscognitive Features)/Complex Partial)
- Automatisms
- Aura
- Amnesia
Generalised onset of seizures:
- Tonic-clonic Grand Mal
- Absence Petit Mal
- GTC
- begin with stiffening of the limbs, followed by jerking.
- cyanosis
- may stop breathing or cease breathing during the jerking.
- incontinence may occur, along with the biting of the tongue.
- patients may appear lethargic, confused or sleepy.
- last for a few minutes to hours. - Absence (petit mal)
- comes and goes without warning
- abrupt, lasts for a few seconds
- no after effects
- persistent staring
- different from complex partial seizures in the sense that:
» there are no auras
» last seconds (rather than minutes
» begin frequently and end abruptly
» produce characteristics EEG pattern “3Hz spike waves”
Diagnosis of epilepsy
- Thorough history-taking is important
- Description of onset, duration and characteristics of a seizure
- Accurate history is best provided by the person who has observed the patients
- Patient is useful in describing details of auras, preservation of consciousness and post-ictal state. - Neurologic examination
- Concomitant medical conditions
Investigations for epilepsy
- Scalp EEG
- Essential tool for diagnosis and classification of seizures and epileptic syndrome.
- If diagnosis of seizures or epilepsy is considered, epileptiform discharges on EEG confirm diagnosis.
- A normal EEG does not exclude possibility of epilepsy.
- Limitations
» Not all epileptic patients have an abnormal EEG.
» EEG can be abnormal in normal persons (false positive) - MRI with gadolinium
- Ordered for: adult patient with first seizure, patients with focal neurologic difficulties, suggestion of focal onset seizure
- Identify focal lesions:
» Mesial temporal sclerosis
» Focal cortical dysplasia
» Remote injury (old stroke etc.)
» Tremor
» Vascular malformation - Biochemical/toxicology
» Rule out electrolyte abnormalities
» Serum prolactin – considerable variability, not used routinely
» Creatine kinase – raised after GTC
Risk after seizure recurrence
- After a single, unprovoked seizure occurring, within the next 5 years, 30%. Risk is higher in the first 2 years.
- Risk of second seizure is higher in the presence of:
» Epileptiform abnormalities on EEG
» Prior brain insult (e.g. stroke, brain trauma)
» Structural abnormality in brain imaging
» Nocturnal seizure - After 2 unprovoked seizures, risk of recurrence is 70%.
- Treatment after first seizure:
» Reduced risk of 2nd seizure
» No effect on long-term prognosis
» No evidence of higher risk of death, injuries or status epilepticus
Treatment goals for epilepsy
- Absence of epileptic seizures
- Absence of anti-epileptic drug (AED)-related side effects
- Attainment of optimal QoL
Factors that influence AED choice
- Seizure type, epilepsy syndrome
- Co-medication and co-morbidity
» Migraine: valproate; Depression/anxiety: levetiracetam with caution
» Drug-drug interactions with HIV patients: immunosuppressants
» Route of elimination: e.g. renal or liver impairment
» Special population:
»> Women with child-bearing potential: levetiracetam / lamotrigine
Pharmacological treatment: general principles
- Monotherapy is preferred
- Initiation of treatment
- Start with low dose of 1st-line AED appropriate for the particular seizure type
- If seizures continue but no side effects occur: gradually increase dose of AED
» Diagnosis should be reviewed
» Ensure that patient has received the appropriate drug for seizure type / epileptic syndrome
» Check adherence - Choice of seizure freedom after failure of first AED is low
- Consider substitution if the first AED produces an adverse drug reaction or is not tolerated at low doses.
- Consider combination therapy if the patient tolerates the first or second AED but with a suboptimal response. - Drug resistant epilepsy:
- Failure of adequate trials of two appropriately chosen, and used AEDs (can be monotherapy, or in combination) to achieved sustained seizure freedom.
Non-pharmacological methods (ketogenic diet)
- Used in patients who cannot tolerate or have not responded well to AED treatment.
- Low carbohydrates, high fat in diet
» Induction of ketosis
» Prevention of seizures (used mainly in young children – evidence)
» Challenging to adhere long term