epilepsy Flashcards
What is SUDEP?
Sudden unexplained death in epilepsy
What are the risk factors for SUDEP?
1) Presence and frequency of generalised tonic-clonic seizures
2) Nocturnal seizure
3) Lack of seizure freedom
What is a seizure?
A seizure is a transient occurrence of signs and symptoms due to synchronous or abnormally excessive neuronal activity in the brain
What is epilepsy?
A brain disorder characterized by an enduring predisposition to generate epileptic seizures
What are the conditions that define epilepsy?
Defined by any of the following condition
1) At least two separate unprovoked seizures episodes occurring > 24 hours apart
2) Diagnosis of an epilepsy syndrome
3) One unprovoked seizure and a probability of further seizures similar to general recurrence risk (60%) after two unprovoked seizure, occurring over the next 10 years
What events can provoke seizures?
1) Electrolyte imbalances
2) Toxic substance/ drugs
3) Structural insults
4) Infectious reasons (CNS infection, Febrile illness)
5) Inflammation
What are some of the electrolyte imbalance that can lead to seizure?
1) Hypoglycaemia
2) Hyponatremia
3) Hypocalcaemia
4) Hypomagnesemia
ALL Hypo
What are some of the structural insults that can lead to seizure?
1) Traumatic brain injury
2) Stroke
What are some of the toxic substances/ drug that causes seizure?
1) Illicit drug (Cocaine, Amphetamines)
2) Drugs (TCA, Carbapemen, Baclofen)
3) Alcohol
4) BZD withdrawal
What are main processes in the pathophysiology of a seizure?
1) Hyperexcitability
2) Hypersynchronization
Seizure activity is characterized by?
Synchronised paroxysmal discharge occurring in a large population of neurons within the cortex
What is hyperexcitability?
Enhanced deposition for a neuron to depolarize
What are main ion channels involved in depolarisation?
1) Voltage gated Na+ channel
2) Voltage gated Ca2+ channel
3) Voltage gated K+ channel
4) Voltage gated Cl- channel
What are the neurotransmitters that can lead to hyperexcitability?
1) Glutamine
2) Acetylcholine
3) Histamine
4) Cytokines
Insufficiency of which neurotransmitters can result in hyperexcitability
Inhibitory neurotransmitters such as
1) Dopamine
2) GABA
What can lead to hypersynchronization?
Intrinsic organization of local circuits can contributed to synchronization and promote generation of epileptiform activity
What cause is significant for childhood epilepsy
Genetic causes (e.g. Fragile X syndrome)
How many mode of onset are there in epilepsy?
2, focal and generalized
Describe “focal onset”
Seizures begins only in one hemisphere. May spread to the contralateral hemisphere
Describe “generalized onset”
Seizure begins in both hemisphere
What is significant in a seizure described to have dyscognitive feature?
Impairment of consciousness
How is impairment of consciousness described as?
Loss of awareness to external stimuli or inability to respond to external stimuli in a purposeful and appropriate manner
How are seizure types classified?
Based on 3 keys features
1) Where does the seizure begin in the brain
2) Level of awareness during the seizure
3) Other features of the seizure
Focal onset seizure without dyscognitive features are classified as?
Simple partial seizure
Focal onset seizure with dyscognitive feature are classified as?
Complex partial seizure
The clinical characteristics of a seizure will depend on?
1) Site of focus
2) Degree of “irritability” of the areas of the brain surrounding the focus
3) Intensity of the impulse
How are the clinical presentation of simple partial seizures classified?
1) Motor symptoms
2) Sensory symptoms
3) Autonomic symptoms
4) Psychic (or somatosensory) symptoms
What are the motor symptoms of simple partial seizures?
1) Clonic movement of the arm, shoulder, leg, face
2) Speech arrest
What are the sensory symptoms of a simple partial seizure?
1) Tingling sensation, feeling of numbness
2) Rising epigastric sensation
3) Visual disturbances
What are the autonomic symptoms of a simple partial seizure?
1) Increased HR and BP
2) Sweating, salivation or pallor
What are the psychic symptoms of a simple partial seizure?
1) Hallucinations
2) Flashbacks
3) Affective symptoms including fear, depression, anger, irritability
What are the clinical presentation of complex partial seizures?
1) Aura
2) Impaired consciousness
3) Automatisms
What are the some of the characteristics of the clinical presentation of complex partial seizures?
1) For Aura, visual disturbances (flashing lights) are similar to that of simple partial seizure
2) Impaired consciousness leads to amnesia to the event
3) Automatisms includes lip smacking/ chewing, picking at their clothing unpurposefully and
What are the type of seizures in generalized onset seizures?
1) Tonic-clonic, “Grand-Mal”
2) Clonic (Jerking)
3) Tonic (Stiffness)
4) Myoclonic
5) Absence, “Petit Mal”
6) Atonic (Rag-doll)
What are some characteristics seen during a tonic-clonic seizure?
1) Cyanosis
2) Stiffening of limbs (Tonic), jerking of limbs and face (Clonic)
3) Incontinence
4) Biting of the tongue, inside of mouth
5) Noisy breathing
What are some characteristics seen after a tonic-clonic seizure?
1) Patient has a headache and appear lethargic, confused or sleepy. Sore muscles
2) Full recovery can take hours or several minutes
What is a myoclonic seizure?
A seizure that involves rapid, brief contractions of bodily muscles on both sides of the body
What is the characteristic EEG pattern seen in Absence seizure?
“3Hz Spike waves”
During history taking what are some of the important things to ask?
Description of onset, duration and characteristics of the seizure
Ask patient for details of aura, preservation of consciousness and post-ictal state
What are some of the investigational tools used in the diagnosis of Epilepsy?
1) Scalp/ Video Electroencephalography (EEG)
2) MRI with gadolinium
3) Biochemical/toxicity labs
What are the limitation of EEG?
Not all epileptic patients have an abnormal EEG.
EEG can be abnormal in normal persons
What are the treatment goals for epilepsy?
1) Absence of epileptic seizure (Seizure freedom)
2) Absence of ADR
3) Attainment of optimal QoL
What are the non-pharmacological option for treatment of epilepsy?
1) Ketogenic diet
2) Vagus nerve stimulation
3) Responsive neurostimulator system (RNS)
4) Surgery
Anti epileptic drug (AED) should be individualised according to …?
1) Seizure type, epilepsy syndrome
2) Co-medication and co-morbidity
3) Patient’s lifestyle and preference
4) National/Institutional guidelines
What are the co-morbidities that we should take note of when giving AEDs?
1) Depression - Use levetiracetam with caution
2) Renal/liver impairment necessitating dose adjustment
3) Pregnancy
4) Migraine - consider topiramate, valproate
What are the advantages of monotherapy?
1) Lower incidence of ADR
2) Absence of DDI
3) Reduced risk of birth defects
4) Lower cost
5) Easier to correlate response and ADR
6) Better adherence
Is monotherapy preferred for AEDs?
Yes
How do we initiate AED treatment?
Start with low doses of an appropriate 1st line AED for a particular seizure type
If seizure continue but there no AED SEs, what do we do?
Gradually increase dose
If seizure continues despite maximum tolerate dose of 1st line AED, what do we do?
1) Review diagnosis
2) Ensure pt has received the appropriate drug for seizure type/ epileptic syndrome
3) Check adherence
When do we consider combination AED therapy?
When the patient tolerates the first and second AED but with a suboptimal response
When do we consider substitution monotherapy?
When first AED produces an ADR/ not well tolerated at low doses/ does not improve seizures
What are the factors to consider when combining AEDs?
1) Patient’s previous clinical response to each drug alone
2) Drug’s MOA
3) Drug tolerability profile
4) Drug PK
What does a ketogenic diet consist of?
Low carbs, high fat
When do we recommend ketogenic diet?
When patient cannot tolerate/ have not responded well to AED treatment
What type of seizure is Vagus nerve stimulator (VNS) indicated for?
Only for intractable focal seizure
How does VNS work?
During a seizure, the subcutaneously implanted stimulator delivers cyclical “on-demand” stimulation to the vagus nerve by placing a magnet next to it
Responsive neurostimulator system (RNS) are indicated for what group of patients?
1) Patient with partial-onset seizures
2) 2 or less epileptogenic foci has been localized
3) Refractory to 2 or more AED
4) Have frequent and disabling symptoms
How does RNS work?
Continuously monitors electrical activity in the brain, detects patient-specific patterns and deliver brief pulses of stimulation when it detect activity that can lead to seizure