Epilepsy Flashcards
define seizure and epilepsy
Seizure - the clinical manifestation of an abnormal, excessive excitation and synchronization of a population of cortical neurons
Epilepsy - a tendency to recurrent seizures >24 hours apart which are not provoked by systemic or acute neurologic insults
what is an EEG?
Electroencephalography
- Records cortical electrical activity, usually from the scalp.
- The most important neurophysiological study for the diagnosis, prognosis, and treatment of epilepsy.
what is the difference between generalised and partial/focal seizures?
generalised - originate within networks distributed across both cerebral hemispheres + cellular/biochemical or structural abnormalities
focal - originate within networks limited to one cerebral hemisphere with semiology affecting the function of affected area + structural abnormalities
how are the seizures classified according to the ILAE 1981?
- classified according to the clinical features of seizures and EEG findings
1. generalised - absence, tonic, clonic, atonic, tonic-clonic, myoclonic
2. partial - simple partial, complex partial (common, TLE) and secondary generalised (common in frontal lobe) - but simple and complex have been eliminated now
- instead depends on cognitive impairment: focal seizure w or w/o dyscognitive features
3. may be focal, generalised or unclear - epileptic spasms (uncladsifieable seizure)
what is the significance of classification of seizures?
- Seizures can be classified based on their clinical and electrographic features (EEG recording).
- Importantly, the diagnosis of a patient’s epilepsy syndrome is based on their clinical history and their seizure type(s).
what are the features of absence seizures?
- formerly known as petit Mal
- staring spell with impaired awareness: patient absent
- brief episodes: 3-20 seconds
- sudden onset and resolution
- patients stop doing whatever he/she was doing, becomes unresponsive but maintains normal posture and muscle tone
- blank expression with sometimes fine flickering of eyelids or face
- often provoked by hyperventilation
- onset typically b/w 4-14 hears if age (young childhood and resolves by age 18
- normal development and intelligence
- EEG: generalised 3Hz spike-wave discharges (slow activity on EEG)
what are the features of myoclonic seizures?
- Brief, shock-like jerk of a muscle or group of muscles
- Differentiate b/w benign, non-epileptic myoclonus (e.g., while falling asleep)
- EEG: Generalised 4-6 Hz polyspike-wave discharges
- muscle tone not normal (??)
what are the features of tonic seizures?
- Symmetric, tonic muscle contraction of extremities with tonic flexion of waist and neck
- Duration - 2-20 seconds.
- EEG – Sudden attenuation with generalised, low-voltage fast activity (most common) or generalised polyspike-wave.
what are the features of atonic seizures?
- Sudden loss of postural tone: severe - falls ; milder - head nods or jaw drops.
- Duration - usually seconds, rarely more than 1 minute
- EEG – sudden diffuse attenuation or generalised polyspike-wave
what are the features of tonic-clonic seizures?
- Associated with LOC and post-ictal confusion/lethargy
- Duration 30-120 seconds
- Tonic phase (30 secs): Stiffening and fall; often associated with ictal cry (due to spams of larygeneal and respiratory muscle) and cyanosis (breathing ceases temporarily)
- Clonic Phase (60 secs): symmetrical convulsions with muscular contraction and relaxation, noisy and poorly coordinated breathing w salivation that appears as frothing at the mouth. may have tongue bitting, other injuries, urine incontinence
- postical coma (30 mins): seizure ends but patients remains unconsciousness, probably due to large-scale release neurochemicals like opiates and GABA
- EEG – generalised polyspikes
what are simple partial seizures/focal seizures w/o dyscongitive features challenging to diagnose?
diverse range of manifestations
a. frontal: motor: clonic repetitive flexion/extension, limb jerking, headache or eye deviation
b. parietal: sensory disturbance - paresthesia (abnormal sensation: tingling, prickling, chilling, burning, numbness)
c. occipital - positive visual disturbance - coloured balls, flashing lights or hallucinations
d. auditory (crude or highly complex sounds)/ Olfactory (intense odours like burning rubber or kerosene)
e. Autonomic sensations- flushing, sweating, piloerection
- as there is a broad range of potential semiology linked to focal seizure so caution is advised before concluding the stereotypic episodes of bizarre or atypical behaviour is not due to seizure activity, thus in such cases, EEG may be helpful to confirm the diagnosis (motor focal seizure: 3-4Hz)
what are the features of complex partial seizures/focal seizures with dyscogntive features/focal seizure w impaired awarness?
- most common TLE
- LOC
- semiology vary with site of origin and degree of spread
1. Presence and nature of aura - peculiar smell, deja vu, jamais vu, euphoria (temporal: deja vu, jamais vu, memories, feeling dread, rising feeling)
2. Automatisms - chewing, lip smacking, picking. at clothing or aimless reaching
3. Other motor activity - Duration typically < 2 minutes
4. postictal confusion or aphasia or anterograde amnesia
what are the features of secondary GTC seizures?
- Begins focally, with or without focal neurological symptoms
- Tonic and clonic phases with variable symmetry, typical duration 1-3 mins
- Postictal confusion, somnolence
- Can have transient focal deficit (Todd’s paresis)
how are epilepsy syndromes grouped?
Grouping of patients that share similar:
- Seizure type(s)
- Age of onset
- Natural history/Prognosis
- EEG patterns
- Aetiology / Genetics
- Response to treatment
what is epilepsy syndrome? describe the heterogeneity in epilepsy
- Epilepsy is an umbrella term, under which many types of diseases and syndromes are included.
- Some authors distinguish between epilepsies and epileptic syndromes, depending on whether seizures are the only neurologic disorder (an epilepsy) or are one of a group of symptoms (an epileptic syndrome).
- Some of the epilepsies (e.g., juvenile myoclonic epilepsy) have well-defined genetics, clinical courses, and responses to medication.
- Others (e.g., temporal lobe epilepsy) have natural histories which are highly variable, and which reflect differences in pathology as well as in host response to that pathologic process and to the treatments administered.
describe the epilepsy syndrome classification
- The 1989 classification of epileptic syndromes: partial or generalised
- depending on whether seizures arise in a circumscribed portion of the brain, or begin diffusely in the cortex and its deep connections
- further subdivides into idiopathic, symptomatic and cryptogenic
describe the following terms
- symptomatic
- cryptogenic
- idiopathic
- symptomatic - known cause + associated w neurologic or neuropsychological abnormality + clear genetic, structural or metabolic cause
- cryptogenic - unknown cause + associated w neurologic or neuropsychological abnormality + assumed to be symptomatic
- idiopathic - unknown cause, suspected to be genetic
give examples of focal/partial epilepsy or epilepsy syndrome for
- idiopathic
- symptomatic
- idiopathic (age related onset) - benign childhood epilepsy with centrotemporal spikes (‘rolandic epilepsy’), childhood epilepsy with occipital paroxysms
- symptomatic - FL, PL, OL, TL epilepsy chronic progressive epilepsia partíais continua of childhood
give examples generalised epilepsy or epilepsy syndrome for
- idiopathic
- symptomatic
- cryptogenic
- idiopathic (age related onset)
- Benign neonatal familial convulsions
- Benign neonatal convulsions
- Benign myoclonic epilepsy in childhood
- Childhood absence epilepsy (pyknolepsy)
- Juvenile absence epilepsy
- Juvenile myoclonic epilepsy - symptomatic or cryptogenic
- west syndrome
- Lennox-gastaut syndrome
what are the features of TLE?
- most common in focal seizures w dyscognitive features
- symptomatic or cryptogenic
- onset at any age
- EEG: temporal lobe epilpetiform discharges
- common cause: sclerosis of hippocampus, small scared - detected T2W MRI
- diagnosis essential as refractory to anticonvulsants treatment but responses well to surgical intervention
what are the features of JME?
- juvenile/ early adolescent onset
- bilateral myoclonic jerks
- GTCS and absences (in 1/3)
- common in the morning after waking up
- exacerbated by sleep deprivation and alcohol
- conserved consciousness unless myoclonus is severe
- idiopathic: family history, genetic studies suggest polygenic cause
- EEG: generalised spike or polyspike/wave discharges often photosensitive (30-40%)
- complete remission uncommon but respond well to anticonvulsant medication
what are the features of west syndrome?
- generalised
- symptomatic or cryptogenic
- infantile onset (begins in first year of life)
- seizure disorder w progressive cognitive decline
- also known as infantile spasms
- Hypsarrhythmic EEG (random high voltage spikes and waves)
- abrupt shock like episodes called salaam attacks
- flexion of upper limbs + neck + hips w knees drawn up against the body
- associated w developmental or perinatal brain injury such as anoxia or encephalitis
what is rate of prognosis in JME?
- longitudinal study of 81 CAE
- 15% of participants w/o remission of CAE had developed JME - longitudinal study of 5 years in 66 JME. in an arab population
- 9 out 10 patients relapsed after VPA discontinuation - longitudinal study of 24 JME
- 11 discontinued treatment: 6 seizure free, 3 myoclonic seizure only, 2 w rare seizures - study of 31 JME
- 21 seizure free, 6 AED discontinued
what are the factors to be considered during choosing an epilepsy medication?
- Seizure type - partial or generalised
- Epilepsy syndrome
- Efficacy - best, ability to stop seizures
- Cost
- Pharmacokinetic profile
- Adverse effects - lowest likelihood
- Patient’s related medical conditions
what are the challenges associated while choosing an epilepsy medication?
- several comparison studies: minimal differences in efficacy of standard AEDs
- thus, differences in profile of expected adverse effect, pharmacokinetic and cost should guide AED choice
- most patients can be optimally managed w single AED therefore, one mist be sure that drug oven has failed before moving on to alternative drug or two drug combination
- if patient has persistent seizures but no adverse effects from the drug then the dose can be increased as tolerated or until seizure control in obtained
- the “therapeutic range” of serum concentrations given is only a guideline—the patient’s clinical state determines the appropriate dose
what are choices of treatment for epilepsy?
- epilepsy medication
2. epilepsy surgery
what did the SANAD study find?
Marson et al. - an unblinded RCT, THE SANAD studied the effectiveness valproate, lamotrigine or topiramate for generalised and unclassifiable epilepsy and found valproate. was effective. for focal but. not generalised
what are the changes in terms after organising the epilepsies?
- partial
- simple partial
- complex partial
- secondary generalised TCS
- cryptogenic
- symptomatic
- idiopathic
- partial - focal
- simple partial - focal w/o impaired awareness
- complex partial - focal w impaired awareness
- secondary generalised TCS - focal evolving to bilateral convulsive seizure
- cryptogenic - unknown
- symptomatic - metabolic/structural
- idiopathic - genetic
what are the variables accounting for the different EEG?
Age - normal EEG of a child is very different from adult
Artefacts - chewing
Conscious Level - sharp waves seen in cortex while sleeping
Drugs - burst depression seen under anaethesia
Cerebral Pathology - cerebral palsy shows abnormal EEG but not necessarily seizures
what are the different activation techniques to induce/record a seizure/abnormal EEG?
- photo stimulation
- hyperventilation: vasoconstriction provokes seizure
- sleep and sleep deprivation
- long term monitoring: ambulatory and video-telemetry
what is the sensitivity of the following epileptiform activity during the following
- wake EEG
- Sleep EEG
- repeat wake and sleep EEG
- wake EEG - 50%
- Sleep EEG- 80%
- repeat wake and sleep EEG - 92%
what is the specificity of EEG?
EEG epileptiform in 0.5 – 4 % healthy adults however the population is not healthy
what are the uses of EEG in epilepsy?
- Diagnosis (ictal) - epilepsy vs non-epilepsy
- interictal period reflecting epileptiform activity consists of bursts of abnormal discharges containing spikes or sharp waves
- epileptiform activity not specific for epilepsy but has a greater prevalence in epileptic population than others
- however, even in an epileptic patient, the initial interictal EEG may be normal up to 60%
- thus, EEG cannot establish the diagnosis of epilepsy in many cases - Classification (ictal/ interictal) - general or focal
- however, absence of EEG seizure activity does not exclude seizure disorder as focal seizures may originate from a region in cortex that cannot be detected by standard scalp electrodes
- since seizures typically infrequent and unpredictable often difficult to obtain EEG during a clinical event
- thus, video EEG telemetry unit for hospitalised patients or use portable equipment to record EEG continuously on cassettes >24h in ambulatory patients
- video approach now a routine approach for accurate diagnosis of epilepsy in patients w poorly characterised events or seizures that are difficult to control - Classifying seizure disorders and aid in the selection of anticonvulsant medications e.g.
- episodic generalised spike-wave activity seen for absence (3Hz) as well as epilepsy syndromes like JME + LGS
- west syndrome: Hypsarrhythmia EEG
- focal interictal epileptiform discharge seen in TLE and frontal lobe discharges
a. frontal: limb jerking, headache or eye deviation
b. parietal: sensory disturbance - spreading tingling
c. temporal: deja vu, jamais vu, memories, feeling dread, rising feeling
d. occipital - positive visual disturbance - coloured balls - monitor the progress
- normal EEG -> better prognosis
- abnormal background or profuse epileptiform activity -> poor
- however, this is also a limitation of EEG in epilepsy - Work-Up for Epilepsy Surgery (ictal/ interictal)- concordance w MRI abnormality
- Management of Status Epilepticus - convulsive or non-convulsive ??
what are the abuses of EEG in epilepsy?
- monitoring of progress - not imp. if EEG changes or not after treatment but imp how patients reposed to the treatment
- anti-convulsant withdrawal in adults - anti-convulsants have better results in children
- diagnosis in the presence of intracerebral disease
- diagnosis where history is of syncope - EEG should not be done of its a blackout
- driving - the regulation change every few years of driving
what are the non-pharmacological epilepsy treatment options?
- Vagal nerve stimulation (VNS)
- Deep brain stimulation (DBS)
- Resective surgery
- Ketogenic diet
- Complementary therapies
what is VNS, when is it used and what are its aims?
- an adjunctive treatment for epilepsy with focal or generalised onset
- it is used for refractory patients who seizures have not been controlled after trial 2/3 medications and are not suitable for resective surgery
- Aims to reduce the frequency and/or
intensity of seizure activity, shorten recovery time and lessen side effects
how is a VNS embedded in the body and how does it work ?
- a pulse generator is impacted into a pocket of skin normally not he left
- wires and electrodes travel under the skin and are connected to the left vagus nerve in the neck
- The stimulator is programmed to send regular, mild electrical impulses to the vagus nerve and can also be controlled by use of a magnet. The newest VNS model is also sensitive to a rise in HR (Eggleston et all, 2014).
what are the benefits of VNS?
- aims to reduce seizure activity by up to 60% interrupting and preventing the electrical irregularities on the surface of the brain, that cause seizures.
- improved alertness and memory and fewer mood problems.
- Therapy is reported to improve over time, side effects lessen over time
- proffered by patients over brain surgery