Epilepsy Flashcards
possible triggering factors? nondrug
Sleep deprivation Sensory overstimulation Hyperventilation (e.g., breathlessness, asthma attacks) Allergies Emotional stress Hormonal changes (e.g., during puberty, pregnancy) Infections & illnesses Head trauma Congenital/perinatal complications
possible triggering factors? drug
Certain drugs (e.g., anaesthetics, antibiotics, antidepressants, NSAIDs, opioid analgesics) may lower the threshold for induction of seizures
Withdrawal of drugs (e.g., alcohol, benzodiazepines, drugs of abuse)
Excessive intake of AED –> supratherapeutic AED-induced ADRs
Missed AED medication –> subtherapeutic serum AED concentration
? Pertussis vaccine (apparent increased risk of febrile seizures)
Basic physiology of a seizure episode can be traced to instability in a single neuronal cell membrane or group of cells around it
Seizure activity is characterised by synchronised paroxysmal discharges occurring in a large population of neurons within the cortex
Basic physiology of a seizure episode can be traced to instability in a single neuronal cell membrane or group of cells around it
Seizure activity is characterised by synchronised paroxysmal discharges occurring in a large population of neurons within the cortex
Excess excitability spreads in Local region
Partial seizure
Excess excitability spreads in Widespread region
Generalised seizure
Biochemical mediators of epileptic seizures:
Abnormal K+ conductance
Defects in voltage-sensitive ion channels
Deficiencies in membrane ion-linked ATPases (usually neuronal membrane instability)
Excessive release of excitatory neurotransmitters (e.g., acetylcholine, histamine, cytokines, etc)
Insufficient release of inhibitory neurotransmitters (e.g., GABA, dopamine)
Abnormalities in intra- & extracellular substances (e.g., Na+, K+, O2, glucose, etc) that may affect normal neuronal activity
Reductions in neuronal threshold to electrical/mechanical stimuli
Excessive tendency for propagation of seizure discharge from focus
Accurate history is best provided is a person who has observed the patient’s repeated events, not necessarily from the patient himself
Accurate history is best provided is a person who has observed the patient’s repeated events, not necessarily from the patient himself
Patient is useful in describing details of auras, preservation of consciousness, and post-ictal state
Patient is useful in describing details of auras, preservation of consciousness, and post-ictal state
Positive identification of the classical characteristics
Aura
Cyanosis
Unconsciousness
Motor manifestations
- Generalised stiffness of limbs and body
- Jerking of limbs
- Tongue biting
- Urinary incontinence
- Post-ictal confusion
- Muscle soreness
- Headaches
Diagnostic procedures
Electroencephalogram (EEG)
- Critical for identifying seizure type & for elderly patients
- False positive results are possible where:
Loss of consciousness is due to syncope
Results do not correlate with other presenting features
Repeated assessment may be useful if first EEG was not conclusive
Magnetic resonance imaging
- Currently the imaging method of choice
- Useful for detecting brain lesions/anatomic defects
- Also recommended for patients refractory to 1st-line antiepileptics
Computed tomography
- Used in urgent cases or if MRI is contraindicated
Video diagnosis
- Increasingly being used for diagnosis in patients with suspected psychogenic non-epileptic seizures (PNES)
Biochemical/toxicology
- Helps to rule out electrolyte abnormalities, renal/hepatic diseases and exogenous toxicity
Serum prolactin
- May help differentiate between PNES in adults and adolescents
Lumbar puncture
- Helps to rule out presence of meningitis or encephalitis in cases where patient exhibits signs of sepsis
Misdiagnosis
Diagnosis may be complicated by resemblance of similar symptoms in other clinical conditions: Loss of consciousness can be due to - Transient cardiac arrhythmia - Transient ischaemic attacks - Hypoglycaemia - Panic attacks
Abnormal kinetic movement
- Movement disorders in sleep and wake
- Tremors / paroxysmal choreoathetosis / dystonia
- Drop attacks or cataplexy
Provoked seizure - Refers to seizures with an obvious and immediate cause - Most commonly associated with: Strokes Trauma Infections Effects of alcohol (intoxication and withdrawal) Sleep deprivation
Determining the type of seizure that has occurred is essential for:
Determining the type of seizure that has occurred is essential for:
Focusing the diagnosis on particular aetiologies
Selecting the appropriate therapy
Providing potentially vital information on prognosis
Partial seizures
Simple partial seizures
Complex partial seizures
Partial seizures with secondary generalisations
Generalised Seizures
Absence seizures Tonic-clonic seizures Tonic seizures Clonic seizures Myoclonic seizures Atonic seizures
Unclassified Seizures
Neonatal seizures
Infantile spasms
ILAE 2017 Classification of Seizure Types
ILAE 2017 Classification of Seizure Types Based on 3 key features: - Where seizures begin in the brain - Level of awareness during the seizure - Other features of the seizure
The clinical characteristics of a seizure will depend on:
The clinical characteristics of a seizure will depend on:
Site of the focus
Degree of ‘irritability’ of the areas of the brain surrounding the focus
Intensity of the impulse
the desired outcomes in the treatment of epilepsy are:
The desired outcomes in the treatment of epilepsy are: Absence of epileptic seizures
Absence of anti-epileptic drug (AED)-related side effects
Attainment of optimal quality-of-life
Treatment
General approach involves:
General approach involves:
Identification of goals of therapy
Must be patient-specific
Goals may change with time
New-onset epilepsy
- Absence of seizures
- Absence of drug-related side effects
- Excellent quality of life
Chronic epilepsy
- Minimisation of incidence of seizures
- Alleviation of drug-related side effects
- Decent quality of life
Good and proper patient assessment
Accurate diagnosis of seizure type determines initial choice of therapy
Early treatment
- DECREASE in risk of seizure recurrence by 50%
no effect on long-term prognosis
Good and proper patient assessment
Accurate diagnosis of seizure type determines initial choice of therapy
Early treatment
- DECREASE in risk of seizure recurrence by 50%
no effect on long-term prognosis
what Patient-related factors also need to be considered when deciding on the tx
Age Comorbid conditions Concomitant medications Risk of non-compliance to treatment or medications Family support Occupational/financial status
Development of a care plan
Compare advantages and disadvantages of various anti-epileptic drugs
Monotherapy is ideal but combination therapy must be considered if monotherapy is inadequate
Follow-up evaluation
Allows for re-assessment, updating and if necessary, revision of care plan
Development of a care plan
Compare advantages and disadvantages of various anti-epileptic drugs
Monotherapy is ideal but combination therapy must be considered if monotherapy is inadequate
Follow-up evaluation
Allows for re-assessment, updating and if necessary,
Non-Drug Treatment
Surgery
Dietary modification
compementary / alternative medicine
Vagus nerve stimulation
Surgery
May be useful in up to 90% of patients with selected forms of epilepsy to achieve improvement of symptoms or seizure free status
Usually advocated as early therapy for specific epileptic syndromes e.g.,
- Temporal lobe epilepsy with vs without mesial temporal sclerosis (70% vs 50%)
- Frontal lobe epilepsy with vs without identifiable lesion on MRI scan (50% vs 25%)
Also considered as a last option (vs continued drug therapy) for certain refractory cases
Dietary modification
Ketogenic diet may be used for patients who cannot tolerate or have not responded well to AED treatment
Comprises low carbohydrate, high fat in diet
- induction of ketosis and production of decanoic acid
- decanoic acid associated with reduction in incidence of certain types of seizures or epileptic syndromes
Supplemental vitamins/minerals (e.g., vitamin B, magnesium) may also sometimes be prescribed
- More useful in replacing any vitamins/minerals lost from the body due to the effects of AEDs (cf. seizure prophylaxis)
Evidence is controversial
- More commonly prescribed in children
- Usually recommended if >2 different treatments have failed
Complementary/alternative medicine
Should not be advised to the epileptic patient
No evidence that acupuncture, chiropractic, herbal medicine, homeopathy, ostopathy, or yoga improve seizure control
Drug interactions may give rise to changes in serum AED concentrations
- St John’s wort phenytoin / carbamazepine
? Evening primrose oil phenytoin / carbamazepine
Some aromatherapy oils may produce an alerting effect on the brain –> increased risk of seizure
- Hyssop, rosemary, sweet fennel, sage, wormwood
Vagus nerve stimulation
Indicated only for intractable partial seizures
Electrodes attached around left branch of vagus nerve as well as connected to programmable stimulator Stimulator delivers cyclical stimulation
During a seizure, ‘on demand’ stimulation can be achieved by placing a magnet next to subcutaneously-implanted stimulator
