Neurology Flashcards
What is SCNA1 associated with?
- The sodium channel, voltage-gated, type I, alpha subunit (SCN1A) gene
- on chromosome 2q24.3
- important in controlling sodium transport into neurons
- Over 150 mutations have been linked to epilepsy
- include genetic epilepsy with febrile seizures plus and DRAVET syndrome
- Specific mutations in SCN1A have also been associated with epilepsy of infancy with migrating focal seizures and familial hemiplegic migraine
- DO NOT use sodium channel blocking anti-seizure medications.
What is Dravet syndrome? (AKA severe myoclonic epilepsy of infancy)
- Associated with SCNA1 gene mutation
- Severe end of GEFS+
- Normally presents first year of life (approx. 6/12)
- Prolonged, febrile and afebrile, focal (usually hemiclonic) and generalized tonic-clonic seizures
- Other seizure types including myoclonic and atypical absence seizures appear between the age of 1 and 4 years
- Same in both sexes
- Onset usually about 6/12 and usually associated with fever (60%)
- Immunisation may trigger earlier onset
- Associated with epileptic encephalopathy
- Head size and neurological examination are usually normal initially, over time ataxia and pyramidal signs may develop. Development is typically normal in the first year of life, with plateauing or regression in later years.
What is Rett syndrome?
- Abnormality of the MEPC2 gene on chromosome on the X chromosome
- other gene implicated is CDKL5
- affects only girls (1 in 8500) (similar defect causes severe encephalopathy in boys)
- Usually de novo
- syndrome involving developmental delay, loss of language skills, and repeated hand wringing movements),
What gene abnormality can associated with atypical Rett syndrome?
- One of the proteins affected by CDKL5 is MECP2 protein
- The cyclin-dependent kinase-like 5 (CDKL5) gene, located on chromosome Xp22, encodes a CDKL5 protein that acts as a kinase (changing activity of other proteins).
What is fragile X syndrome and how is it associated with seizures?
- Usually caused by a trinucleotide repeat expansion in the fragile X mental retardation 1 (FMR1) gene, located on chromosome Xq27.3.
- most frequent cause of familial intellectual impairment - second most common cause of intellectual impairment after Down syndrome.
- elongated face, large or protruding ears, and large testes
- Patients typically have autistic features
- Epilepsy in up to 40% of patients. Seizures and EEG features are similar to those seen in childhood epilepsy with centrotemporal spikes
- Seizures typically improve with age.
- Diagnosis : analysis of the number of trinucleotide repeats using PCR and methylation status using Southern blot analysis.
What is Ohtahara syndrome and what gene abnormality is it associated with? (AKA early infantile epileptic encephalopathy)
- frequent intractable seizures and severe early encephalopathy
- normally tonic seizures
- has onset in the first month of life (range 1-3 months)
- Equal in both sexes
- Head size normal at first
- abnormal neuro and development exam
- Severe GDD with or w/o regression
- May evolve to have West or Lennox Gastaut syndrome.
What is an epileptic spasm?
- sudden flexion, extension or mixed flexion-extension of proximal and truncal muscles, lasting 1-2 seconds i.e. longer than a myoclonic jerk (which lasts milliseconds) but not as long as a tonic seizure (which lasts > 2 seconds).
- Spasms typically occur in a series, usually on wakening
- Spasms may be bilaterally symmetric, asymmetric, or unilateral, depending on whether they are generalised onset or focal onset.
- Epileptic spasms usually occur in a series (several in a cluster) right arrow if singular, consider other seizure types.
What is West syndrome?
- West syndrome is characterized by the onset of epileptic spasms, between 3-12 months of age. Global developmental impairment (with or without regression) is typically seen.
- Ohtahara syndrome or other early onset epilepsies (typically with focal seizures) may evolve to have clinical and EEG features of West syndrome after 3-4 months of age.
- M>F
- May have normal or abnormal neuro exam and normal head
- GDD typically seen at age of onset
What is the difference between self-limited neonatal seizures and self-limiting familial neonatal epilepsy?
-Similar presentation and electrical features
- Familial has a strong Fhx where SLNS
are de novo mutations
-Present day 4-7 of life (term, and term corrected)
-If onset is later (1st 2/12 of life) it is called SL FNE
- Focal and hemi-clonic in nature. May alternate side to side; tonic features, vocalisations, automatisms, focal to bilateral tonic clonic.
-Can occur in clusters, minutes
-Usually remit by 6/12 (usually around 4-6 weeks)
-May develop seizures later on in life
-Normal development
-Some neonates with KCNQ2 (K voltage gated channelopathy) mutations may have myokymia (continuous muscle activity causing stiffness and subtle twitching)
What are the typical EEG features of Self-limited neonatal seizures and self-limiting familial neonatal epilepsy?
- May be normal
- May have theta pointu alternant pattern (seen in half patients) interictal (in-between seizures). NOTE not specific to this type of epilepsy
- Rhythmic spikes or slow waves are seen with ictal events. These may be focal (mainly seen in the centro-temporal regions, although other focal areas may be affected) or generalized
- Abnormal EEG may be enhanced in sleep
What is CDKL5 gene and how is it involved in epilepsy?
- The cyclin-dependent kinase-like 5 , located on chromosome Xp22,
- CDKL5 protein that acts as a kinase (changing activity of other proteins).
- One of the proteins affected by CDKL5 is MECP2 protein.
- Identified in girls with atypical (early onset seizure variant) Rett syndrome. Includes features of classic Rett syndrome (including developmental delay, loss of language skills, and repeated hand wringing movements), but also causes recurrent seizures beginning in infancy.
- Mutations in CDKL5 are also reported in X-linked epileptic spasms with intellectual impairment, seen more commonly in females.
- Mutations in CDKL5 are also reported in Ohtahara syndrome
What is Lennox Gastaut syndrome?
- Multiple types of intractable seizures - tonic seizures in sleep, atonic and atypical absence seizures also occur, focal, spasms, non-convulsive status
- Onset of seizures age 1-7 years old
- Often previous abnormal underlying brain structures
- Cognitive and behavioral impairments
- Diffuse slow spike-and-wave and paroxysms of fast activity on EEG.
- DDX include Dravet syndrome, atypical childhood epilepsy with centrotemporal spikes
- 10-30% have PROGRESSED to this syndrome (i.e WEST or OHTAHARA syndrome)
What is febrile seizures plus ? (or genetic febrile seizures plus)
Syndrome characterised by persisting febrile seizures past normal age and/or accompanied by general seizures ( T/C, atonic, Myoclonic, absence)
- NORMAL development
- Distinguish between the two based on presence of Fhx
- Onset between the age of 6/12 and 6 years.
- Usually self-terminate. Usually resolve by puberty
- Dominant inheritance with incomplete penetrance.
- SCN1A, SCN1B, GABRG2 and PCDH19.
- Background EEG normal
- Ictal EEG depends on kind of seizure type occurring
What is Child absence epilepsy?
- Multiple daily absence seizures, brief (<10 secs)
- V. occasionally may have GTC in adolescents
- Absences >45 secs and post ictal SHOULD NOT happen
- NORMAL development (+ Hx and neuro)
- Genetic/idiopathic in an otherwise normal child
- Onset 2-12 years (peak 5-6 years)
- DDx between 8-12 years is JAE. CAE is FAR MORE frequent
- Provoked by hyperventilation
- SELF-LIMITING
- May have associated ADHD or learning difficulty
- BG EEG normal. 1/3 have occipital intermittent rhythmic delta activity (OIRDA)
- Ictal EEG approx. 3 Hz generalised spike and wave
What is Childhood occipital epilepsy (Gastaut type)?
-Rapid onset and brief (usually <3 minutes) focal visual and sensory seizures. Frequent w/o Rx
-Usually small multi-coloured circles which increase in size and move horizontally. May get deviation or head turning to affected side
-Other sx include ictal blindness, complex hallucinations, eye pain, repetitive eyelid closure/fluttering, headache, N+V
-Post ictal headache in 50%, N+V in 10%
-4% Impaired awareness, 43% hemi-clonic seizure
-Absence seizures post occipital seizure is common
-Onset between 15m and 19 yrs (peak 8-9 yrs)
-Remission in 50-80% in 2-4 years if treated
- NORMAL development and exam
-Epileptic encephalopathy with continuous spike-and-wave during sleep can occur as a co-morbid disorder- Do EEG if cognitive decline
EEG- At ictal onset, there is decr in the usual BG occipital spike or spike-and-wave with sudden appearance of occipital faster rhythms with spikes of low amplitude.
What is childhood epilepsy with centrotemporal spikes? (AKA Rolandic epilepsy)
- Infrequent, brief, hemifacial (lips, tongue, mouth) aka frontoparietal operculum seizures that may evolve to a focal to bilateral tonic-clonic seizure IF they occur nocturnally (not during the day)
- Can get Todd’s paresis
- Seizures >30mins VERY rare
- Onset between 3-14 years (peak 8-9 yrs)
- Self-limiting- usually resolve by age 13 years
- Normal development + exam. Can get abnormal behavioural and neurophysiological deficits if not treated
- Hx of febrile seizures in 5-15%
- Note: consider Fragile X if male with ID
- Inter-ictal EEG shows high voltage centro-temporal spikes activated during sleep and drowsiness
- Ictal EEG – rare to capture. Little literature on it
What is Doose syndrome? (AKA myoclonic/atonic seizures)
- Myoclonic jerks (may be subtle) followed by atonia resulting in a fall (drop attack)
- 2/3 have febrile seizures or GTC PRIOR to onset of m/a seizures
- Onset 6 months - 6 years (peak 2-4 years)
- Epileptic encephalopathy
- M>F 2:1
- Normal Bhx, HC and neuro exam
- Normal development initially may become impaired due to EE
- MUST exclude Glucose transporter defects
- BG EEG- GENERALISED slowing, bi-parietal theta
- Ictal- generalized spike or polyspike with myoclonus. Aftergoing high voltage slow wave with atonia.
What is Landau Kleffnar syndrome?
- Subacute onset of progressive acquired aphasia (from acquired verbal auditory agnosia) on BG of PREVIOUS NORMAL development
- 20-30% DO NOT have seizures (if do they are focal, atypical absence or atonic.
- 40% present with progressive aphasia; seizures or both. Behavioural, psychiatric and cognitive disturbances are common
- Seizures are very infrequent, nocturnal and brief
- Self-limiting BUT often residual significant language impairment (>80%) and can be severe
- Epileptic encephalopathy
- Similar EEG features to other epilepsies with Centrotemporal spikes. Can result as a progression of these
- Onset between 2-8 years (peak 5-7 yrs), remission common by 10yrs old
- Interictal-High amplitude spike and wave is seen in the temporal-parietal regions
What is Juvenile absence epilepsy?
- INFREQUENT absence seizures
- GTC occurs in 80% (usually within 30min of waking)
- Distinguished between CHILD HOOD ABSENCE EPILEPSY have very frequent absence seizures
- Age onset 8-20 years (peak 9-13yrs). Lifelong
- Normal Bhx, HC and neuro exam. NORMAL development
- ADHD and learning difficulties may occur
- May have partially or fully impaired awareness. In impaired awareness can follow simple commands
- Interictal may be generalized spike-and-wave, fragments of generalized spike-and-wave or polyspike-and-wave
- Ictal- Regular 3-6 Hz generalized spike-and-wave or polyspike-and-wave
What can provoke absence seizures?
Hyperventilation well for three minutes. Expect to see on EEG generalized spike-and-wave is seen.
What is Juvenile myoclonic epilepsy?
- Most common genetic/generalised epilepsy
- Myoclonic and GTC (>90%)
- Myoclonic usually distal and within 30m to 1hr of waking
- May get infrequent absence (< daily), very brief, mild impaired awareness (can do simple commands)
- NORMAL development, Hx and exam
- Onset 8-25 years old
- May have Fhx
- Some genes involved. 15q13.3 microdeletion is associated with it
- The EEG shows generalized spike-and-wave and polyspike-and-wave. Photosensitivity is common
What is epilepsy with GTC alone?
- Common genetic/generalised idiopathic epilepsy
- GTC only. Usually within 1-2 hours of waking
- Provoked by sleep deprivation, alcohol and fatigue
- Onset 5-40 yo (peak 11-23 years)
- Lifelong treatment
- NORMAL development, Hx and exam
- Interictal- Generalized spike-and-wave or polyspike-and-wave is seen in the interictal EEG. Half of patients have these abnormalities only in sleep
- Ictal- usually obscured by artefact. Generalized fast rhythmic spikes are seen in the tonic stage. Bursts of spikes and after-coming slow waves are synchronous with clonic jerks
How does Carbamazepine work?
- Iminodibenzyl derative
- Related to TCA’s
- Inhibits voltage gates sodium channels + L-type calcium channels
- Metabolised into active form Carbamazepine-epoxide more so in infants and children = increased risk of toxicity
- Increases metabolism of oral anticoagulants, beta-blockers, haloperidol, felodipine and theophylline
- Interaction with erythromycin can cause carbamazepine toxicity
- Dose range 15-25mg/kg/day
- Adverse reactions: Hypersensitivity rash, ataxia, sedation, nausea, leukopenia, thrombocytopenia
Some of the more common side effects include diplopia and ataxia. It can also cause Stevens Johnson syndrome.
What kind of seizures are treated with Carbamazepine?
Focal seizures
GTC
SE: hypersensitivity rash, ataxia, low plts, low WCC, sedation
What kind of seizures are treated with Sodium Valproate?
All seizure types
SE: N+V, abdo pain, tremor, hair loss, low plt, deranged LFTS
TERATOGENIC (also increased risk of spina bifida)
What kind of seizures are treated with Lamotrigine?
All seizure types including absence/focal
Reduced dosing to 1/3 (5mg/kg/day) if concurrently using sodium valproate
SE: Rash
What kind of seizures are treated with Vigabatrin?
Focal seizures
Infantile spasms
West syndrome
50-150mg/kg/day
SE: Sedation, visual field constriction
What kind of seizures are treated with Ethosuximide?
Absence seizures
20-50mg/kg/day
SE:GI disturbance, rash
What kind of seizures are treated with Topiramate?
All seizure types
6-9mg/kg/day
SE: Anorexia, weight loss, sedation, parasthesiae
What kind of seizures are treated with Clobazam?
All seizure types
2mg/kg/day
SE: Sedation
What kind of seizures are treated with Phenytoin?
All seizure types
5mg/kg/day
SE: N+V, diarrhoea, rash, peripheral neuropathy
MUST monitor levels
What kind of seizures are treated with Phenobarbitone?
All seizure types
5-8mg/kg/day
Not for use as montherapy <16 yo
SE: sedation
What kind of seizures are treated with Levetiracetam?
Focal seizures +/- secondary generalised
Adjunct for myoclonic and GTC
Status loading
No drug interactions
SE: sedation, asthenia, dizziness
How does Levetiracetam work?
Unclear
Can act prophylactically to prevent seizure progression
Rapidly and almost completely absorbed as active form
Not protein bound
Enzymatically hydrolysed in the blood to inactive form and excreted within 24 hours
1/2 life 5-7 hours
Peak plasma approx. 1 hr
How does Clobazam work?
Enhance the effect of GABAa receptors by increasing channel opening FREQUENCY = Increase in calcium ion influx
Rapidly and completely absorbed oral
Peak levels 1-4 hours
Highly protein bound
Metabolised by the liver to active products
Half life elimination is 10-50hrs
How does Ethosuximide work?
Blocks T-type calcium channels in thalamacortical and dorsal root ganglions. Allows normal thalamic activity.
Rapidly absorbed. Almost 100% bioavailability. Active.
Peak levels 3-7 hours
Not protein bound.
Hepatic metabolism into inert substance (20% excreted unchanged in urine)
How does Phenobarbitone work?
Enhances effect of GABAs receptors by increasing channel opening DURATION
90% bioavailability (much lower in neonates due to poor absorption)
Peak levels 1-6 hours (9hrs in neonates)
45% protein bound
Metabolized in liver to inactive substances
Elimination slower in Neonates
Multiple interactions with other meds
Hepatic enzyme INDUCER (CYP450)
- Increases the metabolism of many AEDs such as phenytoin, carbamazepine, valproic acid, lamotrigine and Topiramate
-Some of the more common side effects include nystagmus, gum hypertrophy, hirsuitism, ammonia, liver, rash (associated with Stevens Johnson syndrome), folic acid depletion, decreased bone density.
How does Phenytoin work?
Hydantoin derivate
Inhibits VG sodium channels by reducing frequency of excitability.
Also inhibits calcium channels
Absorbed in the small intestine (more alkaline)
Absorption increased with co-feeding in small children
Bioavailability approx. 95%
Peak levels 2-12 hours
90% protein bound
Metabolized in liver into inert substances
Excreted by the kidneys
Metabolism is saturable at therapeutic levels so beware of toxicity. Lots of variability between patients
Interacts with valproate (binding sites displaced by valproate)
NEED to monitor levels
How does Sodium Valproate work?
Valproate is a short chain fatty acid
Precise mechanism uncertain
Some kind of effect on Voltage gated Na channels
Complete oral absorption and 100% bioavailability
Peak levels 1-2 hours (slower absorption in neonates)
90% bound to protein
Lots of interpatient variability
Metabolised into active substance by liver
1/2 life 6-15hr in kids (10-70hrs neonates)
Inhibits metabolism of many AEDs
Need higher doses of sodium valproate if using with other AEDs
Some of the more common side effects include increased appetite, weight gain, insulin resistance, metabolic syndrome, hair loss, easy bruising (can cause thrombocytopenia and other coagulation abnormalities). It has also been linked to polycystic ovarian syndrome.
How does Lamotrigine work?
Inhibition of use depending voltage sensitive sodium channels
+ undefined mechanisms
Absorbed easily, unaffected by food intake
Bioavailability 95%
Peak levels 1-3 h
55% protein bound
Metabolised by liver into inactive substance
Phenytoin(most effect), phenobarbitone and carbamazepine decrease plasma concentrations
Sodium Valproate reduces the rate of clearance and doubles the half life (CYP inhibitor)
Carbamazepine reduces the half life (CYP inducer)
SE: diplopia and ataxia
What is Tuberous sclerosis?
- autosomal dominant (2/3 sporadic)
- variable penetrance
- defect in protein tuberin (TSC2) or harmatin (TSC1)
- 2 major genes TSC1 (9q34) and TSC2 (16p13)
- tuberin and harmatin regulate protein synthesis and cell size (act like tumour supressor genes)
Involves multiple organs:
- head –> subependymomas, cortical tubers, SEGAs, seizures, cognitive impairment
- heart –> rhabdomyomas (50%), arrythmias
- kidneys –>angiomyolipomas, cysts
- eyes –> retinal harmatomas
- skin –> Shargreen patches, facial angiofibromas, ungal/periungal fibromas (nails), hypomelanotic macules
Seizures may present early with infantile spasms +/- hypsarrthymia on EEG. Later in childhood can be myoclonic
How is TS diagnosed?
At least 2 major criteria OR 1 major + 2 minor
Major criteria:
-head –> subependymomas, cortical tubers, SEGA
-heart –> rhabdomyomas
- kidneys –>angiomyolipomas
- eyes –> retinal harmatomas
- skin –> Shargreen patches(90%) (at least 3), facial angiofibromas(>75%), ungal/periungal fibromas (nails, occur in adolescence), hypomelanotic macules (>3)
Lung- pulmonary lymphangioleioyomatosis
What are classic signs in the early past history suggestive of Dravet syndrome?
Prolonged febrile convulsion Hemiclonic seziures Convulsions post vaccinations Family history of epilepsy May not yet have regression in milestones!
What typical EEG changes do you see in absence epilepsy?
3 Hz spike and wave throughout
frontally dominant
last 2-35 secs