NEURO Flashcards
Definition of status epilepticus
- most seizures are brief and end within 1-3min without treatment - status refers to continual seizure activity or repeated seizures without full recovery between attacks - traditionally lasting for 30min - however need to treat after 5 minutes of continued seizure activity
Causes of acute seizures
- metabolic: hypoglycaemia, hyponatraemia, hypocalcaemia, renal failure - intoxication: drugs or poisons - stroke: haemorrhagic or ischaemic - brain trauma - intracranial infections: meningitis, encephalitis, cerebral abscess - autoimmune encephalitis - hypertensive encephalitis - severe cerebral hypoxia - eclampsia
Antiepileptic management of reversible seizures (i.e. meningitis/eclampsia)
Considering withdrawal of antiepileptic therapy when a minimum for 3 months has elapsed without further seizure activity
Management of acute seizure
- supportive mx: left lateral, protect airway, maintain oxygenation - connect monitoring equipment and gain IVC access - if unable to r.o alcoholic withdrawal give thiamine - if ongoing seizure activity after 5 minutes give 5-10mg IV midazolam or 10mg IM - given antiepileptic: phenytoin and sodium valproate are both first line - if continues to seizure need to intubate
What are the doses of the first line anti-epileptics?
Phenytoin: 20mg/kg IV Sodium valproate: 40mg/kg Same doses for children!
Complications of seizures
- aspiration - trauma - if prolonged: CNS injury, noncardiogenic pulmonary oedema, rehabdo/acidosis/acute renal failure, hyperthermia
Management of acute seizures in pregnancy in eclampsia
- magnesium sulfate 4g IV over 20 min - hydralazine 5-10mg IV over 3-10min, repeat every 20min if needed - midazolam 5-10mg IV - plan birth ASAP - do not give ergometrine
Post seizure follow up
- first episode: FBC, full biochem panel, BSL, UDS and CT head - consider LP if infection suspected and treat with abx - if nil acute cause consider epilepsy - consider anti-epileptic if 2 unprovoked seizures - may need to measure anti-epileptic drug level if able
Classification of epileptic syndrome
- Generalised: idiopathic epilepsy, symptomatic (infection, metabolic, structural, immune) 2. Focal: self limited (benign childhood epilepsy), symptomatic (temporal lobe epilepsy) 3. Focal or generalised: neonatal seizures, West syndrome (infantile spasms) 4. Special syndromes: febrile seizures, status epilepticus, metabolic/toxin induced seizures
Diagnosing epilepsy
- refer to expert to confirm diagnosis and consider rx - diagnosis relies on description of seizures with EEG to support diagnosis - normal EEG does not rule out epilepsy, nor does abnormal EEG confirm diagnosis necessarily - type of seizure influences the choice of drug
Deciding when to treat epilepsy
- seizures are more likely to be recurrent if: partial seizures, abnormal EEG, lesion on neuro-imaging or if abnormal neurological examination > consider starting rx on first seizure in these cases - otherwise generally consider after second unprovoked seizure ** prophylactic treatment in situations of high risk of epilepsy (TBI, tumours or neurosurg) is not recommended*
Initial management of tonic clonic seizures
- First seizure –> investigate cause, EEG + treat cause if able –> is recurrence high risk? NO: observe and treat if further seizure YES: treat after first seizure
Which anti-epileptic would you start after a focal/partial seizure?
Carbamazepine
Which anti-epileptic would you start after a generalised or uncertain seizure?
Sodium valproate
Factors which affect choice of antiepileptic
- type of seizure - pregnancy - adverse effects: weight gain, impaired cognition, hypersensitivity - age (valproate hepatotoxicity more common in infants - cost/ease of use - drug interactions
Which anti-epileptic should be avoided in pregnancy?
Sodium valproate!
Starting an antiepileptic
- start at low dose and slowly increase to target - especially important with lamotrigine to reduce risk of serious skin adverse reactions - exception is phenytoin which can be started at the initial target dose or even with a loading dose - start with a single drug, increase dose until seizure stop or at max dose
When would you add a second antiepileptic drug for epilepsy?
- if seizures are not controlled on first antiepileptic add a second drug - the first drug may be gradually withdrawn to find out if monotherapy is effective with second drug - many patients prefer to stay on combination therapy
How do you withdraw an anti-epileptic drug?
- slow and gradual - usually done over 6 weeks but up to 6 months if clonazepam or barbiturate - driving is not permitted when the dose of anti-epileptic drug is being reduced - driving must not resume until 3 months after completely dose reduction or withdrawal
Ceasing anti-epileptic drug therapy
- driving must stop during dose reduction and for 3 months after the last dose, hence many patients opt to continue therapy indefinitely - do not try and withdraw until at least 2 years after last seizure - risk of seizure recurrence after withdrawal of therapy after 2 years seizure free is ~50% - if seizure after withdrawal or drug decrease restart on previous effective dose (can resume driving within 1 month after this) - juvenile myoclonic epilepsy high high recurrence rate so best not to withdraw therapy
What are the serious adverse effects of specific anti-epileptics?
- sodium valproate: hepatic failure - carbamazepine: agranulocytosis - serious skin reactions (SJS, TEN, DRESS) higher risk in patients of Asian origin - monitor vitamin D concentration in patients on long term anti-epileptics
When to measure serum concentration of anti-epileptics
- for many correlation between serum concentration and efficacy or toxicity is poor - may need to use to check compliance/concordance with therapy, help diagnose if symptoms/signs are due to toxicity - guide dosage for phenytoin - adjust dosage of lamotrigine in pregnancy - when dose is change need to wait 5 half lives before re-checking
Phenytoin monitoring
- nonlinear pharmacokinetics makes monitoring and dose adjustment difficult - small change in dose can cause a large change in steady state serum concentration - if serum concentration <30mcgmol/L (<7mg/L) can increase by 100mg, if concentration >30mcg/mol only increase by 50mg
Advice for patients with epilepsy
- seizures can be provoked by sleep deprivation, ETOH, illegal stimulants, psychological stress, some drugs - avoid situations where a seizure may be dangerous (unsupervised swimming, climbing, operating machinery) - legal obligation to report condition to transport
Contraception in patients with epilepsy
- drugs used to treat epilepsy reduce efficacy of hormonal contraception by induction of hepatic enzymes - carbamazepine, phenytoin, topiramate all reduce OCP efficacy - lamotrigine may also reduce efficacy of COC and the pill may increase lamotrigine metabolism
Which common anti-epileptics do not affect hormonal contraception?
- levetiracetem (keppra) - sodium valproate
Which common anti-epileptics make OCP less effective?
- carbamazepine, phenytoin, topiramate, lamotirigine
Planning pregnancy with epilepsy
- refer all to specialist! - babies born to mother on anti-epileptics have a 4-6% risk of major congenital malformations (2 x the baseline risk) - there is no “drug of choice” in pregnancy but priority is to avoid seizures - use monotherapy if possible, minimise antiepileptic dose - avoid sodium valproate if able, wait 3 months prior to planning conception! - advise 5mg folic acid daily for at least 3 months prior to conception
Monitoring of antiepileptic dose during pregnancy
- concentrations of some drugs will fall in pregnancy - may need to increase dose of lamotrigine - should establish baseline concentration pre-preg - check serum concentration at least every 2 months during pregnancy and aim to keep level near baseline
Teratogenic effects of anti-epileptic drugs
- sodium valproate increases risk fo spinal bifida 10 fold - also associated with lower intelligence and greater risk of learning difficulties - effects are dose related, at daily doses 600-800mg sodium valproate’s teratogenicity are similar to other anti-epileptics - however valproate is often the only drug which controls idiopathic generalised epilepsy, but usually low doses are sufficient - phenytoin increases the risk of congenital abnormalities -
Management of known prolonged/repetitive seizures
- management plan to be formed - if seizure > 5 min or seizure seizures (3 or more in 1 hour) can give 5-10mg midazolam buccally or intranasally
Juvenile absence epilepsies
- genetic/idiopathic generalised seizures - onset for absence epilepsy is 4-9 years old or 10-15 - ethosuximide and sodium valproate are equally effective but ethosuximide is better tolerated and better in girls of child bearing potential - need to ensure girls have reliable contraception!
Juvenile myoclonic epilepsy
- most common form of genetic/idiopathic generalised epilepsy in adults despite its name - typically presents with tonic clonic seizure with background of myoclonic jerks - respond to sodium valproate - if possible try to avoid sodium valproate in young females of childbearing potential who do not have relative contraception - levetiracetam and lamotrigine are alternatives
What is Lennox-Gastaut syndrome
- symptomatic generalised epilepsy characterised by > significant intellectual disability > slow spike-wave pattern on EEG - multiple seizure types - first line therapy is sodium valproate
Management of focal/partial seizures
- patient may be aware (simple partial seizure) or have impaired awareness (complex partial seizure) - treatment of choice = carbamazepine
What is the most common form of structural focal epilepsy?
Mesial temporal love epilepsy due to hippocampal sclerosis
What is the earlier sign of dose related carbamazepine toxicity?
- diplopia starting 30-60min after morning dose
Management of seizure when generalised or focal onset is unclear
Sodium valproate in children/adults and females who have reliable contraception or are unable to have children Levetiracetem in females of childbearing potential who do not have reliable contraception is first line
What is West syndrome?
- infantile spasm - onset usually 4-12 months - sudden brief contraction of head/neck/trunk usually in flexion but sometimes in extension - characteristically spasms occur in runs lasting several minutes - rx: prednisolone
Most common cause of neonatal seizure?
- hypoxic-ischaemic encephalopathy - intracranial haemorrhage - perinatal ischaemic strokes - treatable causes: meningitis, hypoglycaemia, electrolyte disturbances, metabolic conditions - some are benign and familial
What is first line treatment for neonatal seizures?
- phenobarbitone
Febrile seizures
- febrile convulsion is a seizure that occurs from 3 months to 6 years associated with fever > 38 without concurrent acute intracranial disease, metabolic disturbance or CNS infection - reducing temp does not prevent or stop febrile seizures - most are self limiting and end within 1-3 minutes - treat with midazolam if > 5 min
What is the paediatric dose of midazolam for complex febrile seizures?
- buccally/intranasal midaz: 0.2-0.3mg/kg - IM 0.15-0.2mg/kg If seizure ongoing for 10 minutes after second midaz dose treat with anti-epileptic rx
Benign childhood epilepsy with centrotemporal spikes
- starts mid childhood - seizures generally occur during sleep and begin in face or mouth - produce typical “glugging” sounds - speech arrest is common - excellent prognosis, most children seizure free by adolescence - rx: carbamazepine/sodium valproate but rx is not always indicated
Differential diagnosis of epileptic seizure
- syncope - psychogenic non-epileptic seizures - migraine - TIA - paroxysmal dyskinesia - parasomnia
Describe how a generalised absence seizure may present
- “petite mal seizure” - frequent (more than daily) - brief (<30sec) - episodes of behavioural arrest without prominent motor features and immediate recovery of alertness
What is a focal seizure?
- seizures confirmed to one cerebral hemisphere - can evolve to become generalised/bilateral - can have motor, somatosensory, autonomic, visual, auditory disturbances - focal seizures may not impair consciousness (simple focal) but if they do they are “complex focal seizures”
Common causes of provoked epileptic seizures
- acute neurological insult: stroke, trauma, infection, inflammation - biochem: hyper/hypo glucose + sodium + calcium, hypomagnesaemia
What are the common side effects of phenytoin?
- hirsuitism - acne - gum hypertrophy - rash/SJS
AED and SJS
- severe cutaneous adverse reaction seen with carbamazepine, phenytoin, phenobarbiton, primidone, lamotrigine - occurs generally in the first 8 weeks of exposure - to prevent this in patients on lamotrigine need to start low and slowly increase - patients of Chinese heritage have a higher risk (need to consider HLA testing in these patients prior to starting carbamazepine)
Which AEDs can be monitored in serum?
Carbamazepine, phenytoin, valproate, lamotrigine - however the best dose is the one at which seizures are controlled and nil adverse effects are seen - may need to monitor drug levels when adherence is in question or altered pharmacokinetics are expected (pregnancy)
Epilepsy and driving
- patients with epilepsy on AEDs and patients after their first seizure are fit to return to driving after being seizure free for 6 months
What are the enzyme inducing AEDS?
- carbamazaepine - topiramate - oxycarbaxepine - phenytoin These all reduce the efficacy of the OCP by increasing oestrogen and progesterone clearance - strategies include: double dosing bills, using active pills continuously - depot and IUD remain effective however implanon efficacy will be reduced by the above AEDs
What are the 4 classifications of dizziness?
- vertigo: spinning sensation 2. disequilibrium: feeling of imbalance 3. light-headed: sensation of giddiness 4. presyncope: sensation of feeling faint
What are the 2 broad classifications of vertigo?
Central (cerebellum, brain stem) Peripheral (inner ear and vestibular nerve)
What serious causes must be considered in patients presenting with vertigo?
- CVA - tumour - MS
What features associated with vertigo suggest a central cause?
- suspect a central cause if associated with weakness, dysarthria, sensory changes, ataxia or confusion - always think about the vascular risk factors: smoking, diabetes, obesity, HTN, high cholesterol
What features associated with vertigo suggest a peripheral pathology?
- nausea, vomiting - hearing loss
Whihc medications can affect the vestibular system and in turn cause vertigo?
- Frusemide - salicylates - antihypertensive agents
What is Tullio phenomenon?
- loud noises precipitating vertigo in patients with peripheral causes
When would you suspect a perilymphatic fistula in patients with vertigo?
After recent head injury - signs: vertigo induced by valsalva manouvres or by pushing tragus
What are the 2 conditions in which vertigo with hearing loss in seen?
Labrynthitis or Meniere’s disease - hearing loss in not seen in BPPV or vestibular neuronitis
Physical examination of vertigo
- ear examination: should check for vesicles or reaction as seen in cholesteotoma - vertigo triggered by pushing the tragus or with valsalva is seen in perilymphatic fistula - check hearing - neurological examination: focusing on gait, balance, coordination with Romberg’s and heel toe, cerebella examination - eye examination: looking for nystagmus
What does vertical nystagmus indicate?
Central vertigo cause ONLY - can also cause horizontal, rotational and doesn’t disappear on fixing the gaze
When nystagmus is seen with peripheral causes
- nystagmus will disappear with fixation of gaze in peripheral causes
What specialised tests can be done for vertigo?
Dix-Hallpike: sitting on edge of bed, examined turns patients head 30-45 degrees to side being tested and quickly lies supine and hyperextends the neck (horizontal nystagmus is a positive test) Orthostatic BP check: 20mmHg is a significant postural drop Head impulse test: pt looks at examiners nose and examiner quickly turns patients head 10-20 degrees, if abnormal eyes move rapidly and repetitively failing to re-fixate on nose
What are the most common causes of vertigo seen in primary care? (4)
- Labrynthitis 2. Vestibular neuronitis 3. BPPV 4. Meniers BPPV is THE most common cause seen
Which causes of peripheral vertigo cause hearing loss and tinnitis?
Labrynthitis and Menier’s - Menier’s occurs spontaneously and lasts for hours - Labrythitis is provoked by change in head positive and episodes last for few seconds to minutes
What are the diagnostic features of vestibular neuronitis
- usually provoked by recent URTI - attacks last for seconds to minutes - often will be very unbalances - nil hearing loss
What causes BPPV?
- accumulation of calcium crystals in the posterior semicircular canal - crystals effects movement of endolymph causing vertigo - causes brief episodes of vertigo and are associated with nausea and nystagmus - episodes are triggered by rapid changes in head position - nystagmus in BPPV has a rotation nature - diagnosed by Dix-hallpike
Which manoeuvre is used to treat BPPV?
Epley’s 1. Sit with patient on the bed 2. With neck hyperextended and laterally rotated to 45 deg patient is asked to lie supine 3. Remain supine for 1 minute 4. Head is then turned to the opposite side with lateral rotation of 45 deg, remain in this position for further 1 min 5. Rotate head, chest and pelvis to almost prone, hold for further 1 minute 6. quickly sit patient up right with head tilted to the affected side
When should Epley manouvre NOT be performed?
- in patients with neck injury, carotid stenosis and heart disease
Acute labrynithitis
- inflammation of the labyrinth - presents with vertigo, hearing loss, often preceded by a viral infection - middle ear infections can spread to the inner ear and cause labrynthitis - symptoms range from days to weeks - hearing loss is main distinguishing factor - no treatment but if suppurative should drain OM
Meniere’s disease
- uncommon cause of vertigo - thought to be due to increased fluid in endolymph - commonly seen in women - classically presents with episodes > 20min, tinnitus, sensorineural hearing loss and aural fullness - eventually hearing loss becomes permanent - not cure and treatment is symptomatic - mainstay of treatment is betahistine
What is the treatment for Meniere’s?
Betahistine
Vestibular neuronitis
- inflammation of vesticular nerve - precedes viral UTI or herpes zoster infection - common in middle ages adults - acute onset vertigo without hearing loss or tinnitus - vertigo symptoms are aggravated by change in position -loss of balance is more prominent in VN, commonly patients will present after a fall - vertigo is initially severe and lasting fro 2-3 days followed by a gradula recovery which can take 2-6 weeks - bed rest and antiemetics used from 24-72 hours
Indication for neuroimaging in vertigo
- examination not fitting with peripheral lesion - prominent risk factors for CVA are present - neurological signs and symptoms present - vertigo with accompany headache
What lifestyle changes are recommended in patients with vertigo?
- salt restriction - avoid alcohol and coffee - referral to physio for vestibular rehab
Pathophysiology of multiple sclerosis
- multifocal CNS disorder characterised by inflammatory demyelinating lesions affecting white and grey matter - thought to be mediated by autoreactive T cells - causes irreversible axonal injury from outset - steady accumulation of CNS damage leads to irreversible disability
Aetiology of MS
- complex interaction of environmental and genetic factors - environmental: EBV exposure and smoking - later age of exposure to EBV is associated with a higher incidence of disease - HLA-DRB1 has strongest genome correlation
Describe the natural history and disease phases of MS
- Clinically isolated syndrome: first demyelinating event, most commonly isolated episode of long tract motor and sensory deficits, optic neuritis, brain stem syndrome 2. Relapsing remitting MS: relapse shows by symptoms of acute inflammatory demyelinating event in CNS lasting at last 24 hours, complete resolution may occur but mild residual symptoms persist in up to 40% of attacks 3. Secondary progressive MS: after 10 years ~40% of patients with RRMS transition to progressive accumulation of disability without relapses, risk of this transition is greater to 80% 4. Primary progressive MS: 15-20% of patients have progressive disease from onset without relapse or remission, commonly see slow progressive spastic parapresis followed by cerebellar or hemiplegic syndromes. This stage/disease does not respond to rx
Investigation and diagnosis of MS
- clinical diagnosis supported by MRI and CSF findings of oligoclonal bands and raised IgG index with evoked potential studies - diagnosis can only be confirmed histopathologically but need to resort to biopsy is rare
What criteria is used to diagnose MS?
McDonald criteria - > 2 clinical attacks with > 2 lesions = diagnostic - > 2 clinical attacks, with 1 lesion with history suggestive of previous lesion = diagnostic - > 2 clinical attacks, with 1 lesion and dissemination in space evident on MRI without evidence of previous lesion Clinically isolated syndrome = 1 attack with > 2 lesions with objective clinical evidence, with dissemination on MRI or CSF oligoclonal bands
What are the common sites and signs of acute inflammatory dyemyelinating events of MS?
- Optic nerve: pain in eye, blurred vision, reduce visual acuity 2. Cerebellum: unsteadiness, ataxia, evoked nystagmus 3. Spinal cord: usually multifocal and asymmetric, upper or lower limb weakness or parasthesia 4. Brainstem: blurred or double vision, opthalmoplegia 5. Bladder/bowel: constipation, urge incontinence, erectile dysfunction, urinary frequency
Typical sites of lesion on MRI in MS
- periventricular white matter - juxtacortical white matter - corpus callosum - optic nerve - infratentorial structures (pons, peduncles, cerebellum) - spinal cord
DDx of MS
- Neuromyelitis optica (Devic disease) - Acute disseminated encephalomeylitis (monophasic autoimmune disease seen more commonly in paeds, can be triggered by viral illness or vaccination) - migraine - cerebral neoplasma - nutritional deficiencies: B12 or copper - spinal cord compression - infections: syphilis and HIV - SLE - paraneoplastic syndromes - functional symptoms - recurrent infarction