Neurology Flashcards
What is the clinical tetrad of narcolepsy
Patients with narcolepsy present with a clinical tetrad of excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, and sleep paralysis.
Define Guillain-Barré syndrome
GBH aka Acute inflammatory demyelinating polyneuropathy.
demyelinating disease of the PNS
Explain the aetiology / risk factors of Guillain-Barré syndrome
An inflammatory process where antibodies after a recent infection reacts with self-antigen on myelin or neurons.
There are rare axonal variants with no demyelination.
Often no aetiological trigger is identified (idiopathic in about 40%), in other cases: .
- Post-infection (1– 3 weeks): BACTERIAL: (e.g. Campylobacter jejuni, mycoplasma pneumoniae) or VIRAL: HIV, herpes viruses (e.g. zoster, CMV, EBV). .
- Malignancy (lymphoma, Hodgkin’s disease).
- Post-vaccination (including flu vaccine!)
Note that the bacteria and viruses don’t directly damage the myelin sheath. They have antigens that look similar to the lipids in the myelin sheath. Aka molecular mimicry. So the myelin becomes an autoantigen (=normal component of the cell triggers an immune response).
The myelin autoantigens are bound by dendritic cell, which then activates helper T cell, which releases cytokines to activate B cells which produce Abs against the myelin, and macrophages, which bind to the Abs and strip the myelin off.
The demyelination is segmental (happens in patches along the axon).
At first you get remyelination, as Schwann cells try to make more myelin, but eventually the myelin depletes as the schwann cells can’t keep up
Summarise the epidemiology of Guillain-Barré syndrome
Annual UK incidence is 1– 2 in 100 000. Affects all age groups.
Recognise the presenting symptoms of Guillain-Barré syndrome
Based on nerves affected
Progressive symptoms of 1 month duration of:
- Ascending paraesthesia (affects nerves that convey vibration and touch sensation)
- Ascending symmetrical limb weakness (lower > upper).
Cranial nerve involvement (e.g. dysphagia, dysarthria and facial weakness). Double vision
In severe cases, the respiratory muscles may be affected.
Autonomic: constipation, urinary incontinence
Miller– Fisher variant (rare) : Opthalmoplegia, ataxia and arreflexia.
Recognise the signs of Guillain-Barré syndrome on physical examination
General motor: hypotonia, flaccid paralysis, arreflexia (typically ascending upward from feet to head)
General sensory: impairment of sensation in multiple modalities (typically ascending upward from feet to head)
Cranial nerve palsies (less frequently): Facial nerve weakness (lower motor neuron pattern), abnormality of external ocular movements, signs of bulbar palsy. If pupil constriction is affected, consider botulism
Type II respiratory failure: Identify early. Co2 flat, bounding pulse, drowsiness.Can be insidious and needs regular assessment
Autonomic function: Assess for postural BP change and arrhythmia, urinary difficulties and constipations
Identify appropriate investigations for Guillain-Barré syndrome and interpret the results
Briefly, treatment?
- Lumbar puncture: increased CSF protein/albumin (albuminocytologic dissociation) but white cell count and glucose normal (but normal CSF shouldn’t delay treatment if there is high clinical suspicion)
- Nerve conduction study: reduced conduction velocity or conduction block, but can be normal in early phase of disease
- Blood: anti-ganglioside Abs +ve in the Miller-Fisher variant and 25% of GBS cases; consider C. jejuni serology
- Spirometry: reduced FVC indicated ventilatory weakness
- ECG: arrhythmia may develop (sign of autonomic dysfunction)
Treatment for control of symptoms and to calm the immune system:
- IVIg
- Plasmapheresis
People typically recover over a few months
Outline the order that reflexes are lost in in GBH
Firstly ankle reflex, then patella and arm reflexes
Define motor neurone disease
What are the subtypes?
A progressive neurodegenerative disorder of cortical, brainstem and spinal motor neurons (lower and upper motor neuron).
Various subtypes:
- Amyotrophic lateral sclerosis (ALS) or Lou Gehrig’s disease: combined degeneration of upper and lower motor neurones producing a mix of UMN and LMN neurones.
- Progressive muscular atrophy variant: Only LMN signs, e.g. flail arm or flail foot syndrome. Better prognosis.
- Progressive bulbar* palsy variant: 1 Dysarthria and dysphagia with wasted fasciculating tongue (LMN) and brisk jaw jerk (UMN).
- Primary lateral sclerosis variant: UMN pattern of weakness, brisk reflexes, extensor plantar responses, without LMN signs.
* the bulbar region is made up of the brain stem minus the midbrain and plus the cerebellum
Explain the aetiology / risk factors of motor neurone disease
Unknown.
Free radical damage and glutamate excitotoxicity have been implicated because mutations in superoxide dismutase (SOD1 gene) affect 20% with familial motor neuron disease and 1– 4% of sporadic cases.
SOD1 codes for a metalloenzyme for the conversion of free radicals.
Pathology: Progressive motor neuron degeneration and death with gliosis replacing lost neurons. Neurons may exhibit intracellular inclusions (neurofilaments or ubiquinated inclusions) containing the TAR-DNA binding protein 43 (TDP-43).
Association: Associated with frontotemporal lobar dementia (FTLD) from proganulin mutations.
Summarise the epidemiology of motor neurone disease
Rare mean age 55. 5-10% could have family history with autosomal dominant inheritance
Recognise the presenting symptoms of motor neurone disease
Weakness of limbs (focal or asymmetrical)
Speech disturbance (slurring or reduced volume)
Swallowing disturbance (choking on food/nasal regurg)
Behavioural changes (disinhibition, emotional lability)
Recognise the signs of motor neurone disease on physical examination
Combination of UMN and LMN signs, offten affecting several regions ASYMMETRICALLY
LMN: muscle wasting, fasciculations (particularly on tongue), depressed/absent reflex
UPM: spastic weakness, brisk reflexes, extensor plantars
Sensory examination: SHOULD BE NORMAL
Identify appropriate investigations for motor neurone disease and interpret the results
investigations aimed to confirm the diagnosis by providing evidence of combined UMN and LMN loss and excluding other causes.
Diagnosis is made with clinical reference, with a
nerve conduction study
, and electromyography
Blood: mildly raised CK, ESR. Consider testing for anti-GM1 ganglioside Abs (present in multifocal motor neuropathy,a progressive disorder that does not affect the brain, and isn’t MND)
Nerve conduction studies: Most often normal
Electromyography (EMG): Features of acute and chronic denervation with giant motor unit action potentials in more than 1 limb and/or paraspinals. EMG is an obligatory investigation in motor neurone disease to demonstrate the widespread denervation and fasciculation required for secure diagnosis
MRI: to exclude cord or root compression, and brainstem lesion in progressive bulbar palsy variant. May show high signal in motor tracts on T2 imaging
Spirometry: to assess respiratory muscle weakness (FVC)
Define:
i. bulbar palsy
ii. psuedobulbar palsy
iii. multifocal motor neuropathy
1 Bulbar palsy: Any lesion affecting cranial nerves (IX– XII) at nuclear, nerve or muscle level, presenting with nasal speech, nasal regurgitation of food, especially fluids (palatal weakness), reduced gag reflex, absent jaw jerk, wasted fasciculating tongue.
- Pseudobulbar palsy: Any UMN (corticobulbar) lesion to the lower brainstem, presenting with monotonous or explosive speech, dysphagia, increased gag reflex, brisk jaw reflex, shrunken immobile tongue, emotional lability, UMN limb spasticity and weakness.
- Multifocal motor neuropathy: Characterized by asymmetrical LMN signs. Important to distinguish from MND as treatable. Motor nerve conduction studies show evidence of conduction block, representing focal demyelination. Associated with GM1 autoantibodies. Treatable with intravenous immunoglobulin, steroids or immunosuppression.
Define encephalitis
Inflammation of the brain parenchyma.
Explain the aetiology / risk factors of encephalitis
- What about in immunocompromised?
- Non infective causes?
In the majority of cases encephalitis is the result of a viral infection.
Virus : Most common in the UK is HSV. Other viruses are herpes zoster, mumps, adenovirus, coxsackie, echovirus, enteroviruses, measles, EBV, HIV, rabies (Asia), Nipah (Malaysia) and arboviruses transmitted by mosquitoes, e.g. Japanese B encephalitis (Asia), St. Louis and West Nile encephalitis (USA).
Non-viral: (rare) e.g. syphilis, Staphylococcus aureus.
Immunocompromised : CMV, toxoplasmosis, Listeria.
Autoimmune or paraneoplastic: May be associated with antibodies e.g. anti-NMDA or antiVGKC.
Summarise the epidemiology of encephalitis
Annual UK incidence is 7.4 in 100 000.
Recognise the presenting symptoms of encephalitis
Subacute (hours to days): Headache, fever, n&v, neck stiffness, photophobia, (i.e. symptoms of meningism meningoencephalitis) with behavioural changes, drowsiness and confusion
Often seizures
Focal neurological symptoms (dysphasia and hemiplegia) may be present
Obtain detailed travel Hx
Recognise the signs of encephalitis on physical examination
Reduced level of consciousness with deteriorating GCS, seizures, pyrexia
Signs of meningism: neck stiffness, photophobia, kernig’s test +ve (as it is in SAH).
Signs of increased ICP: papilloedema, HTN, bradycardia
Focal neurological signs, minimental examination may reveal cognitive or psuchiatric disturbances
Identify appropriate investigations for encephalitis and interpret the results
MRI findings if HSV?
U&Es findings?
Bloods:
FBC (raised lypmh), U&E (SIADH may occur), glucose (compare with CSF glucose- low CSF glucose compared to plasma are seen in bacterial meningitis, malignant involvement of meninges and sarcoidosis, but normal in viral infections of the CNS), viral serology, ABG
MRI/CT brain: excludes mass lesion, HSV produces OEDEMA OF THE TEMPORAL LOBE on MRI
LP: Increase lymphocytes, monocytes, protein but glucose usually notmal. CSF culture is difficult, viral PCR now first line
EEG: May show epileptiform activity, e.g. spiking activity in temporal libes
Brain biopsy: very rarely performed
LP: blood (rule out SAH)
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Define meningitis
Inflammation of the leptomeningeal (pia mater and arachnoid) coverings of the brain, most commonly caused by infection.
Explain the aetiology / risk factors of meningitis
BACTERIAL:
Babies <3 months:
Group B streptococcus, E Coli, L monocytogenes
Children and babies >3 months:
N meningitidis, S pneumoniae, H influenzae (now rare due to vaccine).
Adults:
N meningitidis, S pneumoniae, TB
Elderly:
S pneumoniae, L monocytogenes
*Staph Aureus with Hx of neurosurgical procedures of trauma to the head
Other, less common but important bacterial causes:
- Mycobacterium tuberculosis (Hx of exposure to TB, e.g. infants in endemic areas)
- Lyme meningitis (spirochete Borrelia burgdorferi, Hx travel to endemic region)
- Rock mountain spotted fever (Rickeettsia reicketsii, carried by dog tick, endemic to central & south america)
- Neurosyphilis (rare in sexually active individuals esp immunocompromised ones)
ASEPTIC:
VIRAL:
Enteroviruses (Coxsackie or Echovirus) are most commmon cause of viral meningitis, mumps, HSV, VZV, HIV.
FUNGAL:
Cryptococcus (associated with HIV infection).
PARASITES:
Naegleria fowleri: “brain eating amoeba)
OTHERS: Aseptic meningitis, Mollaret’s meningitis
RISK FACTORS: Close communities (e.g. dormitories), basal skull fractures, mastoiditis, sinusitis, inner ear infections, alcoholism, immunodeficiency, splenectomy, sickle cell anaemia, CSF shunts, intracranial surgery.
Most common cause of aseptic meningitis?
Aseptic meningitis : Characterized by clinical and laboratory evidence for meningeal inflammation and negative routine bacterial cultures
Most common cause entrovirus
Recognise the presenting symptoms of meningitis
TRIAD: Fever, headache, , neck rigidity,
Other common: photophobia, irritability, drowsiness, vomiting, high-pitched crying or fits. clouding of consciousness.
Time course:
Acute bacterial meningitis & HSV meningoencephalitis- Hrs to few days
Viral meningitis, cryptococcal meningitis : days to weeks
TB, sypholis: over months
Recognise the signs of meningitis on physical examination
Signs of meningism: Photophobia, neck stiffness (Kernig’s sign: with hips flexed, pain/resistance on passive knee extension; Brudzinski ‘s sign: flexion of hips on neck flexion).
Signs of infection:
Fever, tachycardia and hypotension, skin rash (petechiae with meningococcal septicaemia), altered mental state.
Identify appropriate investigations for meningitis and interpret the results
-What do 2 of the main causative organisms look like under microscopy
Blood: 2 sets of blood cultures (do not delay Abx)
Imaging: CT scan to exclude mass lesion/raised ICP before doing an LP (or it may lead to cerebral herniation during subsequent CSF removal)/
CT head must be done before LP in patients with: immunodeficiency, history of CNS disease, reduced consciousness, fit, focal neuro deficit or papilloedema
LP: Note opening CSF pressure. Send CSF for microscopy with, culture, sensitivity and Gram staining ( Streptococcus pneumoniae : Gram-positive diplococcic, Neisseria Meningitidis : gram-negative diplococcic), biochemistry and cytology.
Bacterial infection on LP: cloudy CSF, WBCs in 1000s with neutrophil pleocytosis (>80%), protein, reduced glucose (CSF: serum glucose ration of <0/5)
Viral infection on LP: WBCs in 100s with lymphocytic pleocytosis (>50%), protein but NORMAL glucose
Note that in fungal and TB meningitis, WBCs in 100s but there is mononuclear pleocytosis (>50%)
TB: Fibrinous CSF, increased lymphocytes. raised protein and reduced glucose
Staining of petechiae scrapings may detect meningococcus in ~70%. Additional studies e.g. viral PCR, staining/culture for mycobacteria and fungi, HIV test depending on the clinical presentation/CSF findings.
Generate a management plan for meningitis
ABx:
Immediate IV/IM antibiotics if meningitis suspected (before lumbar puncture or CT).
Third-generation cephalosporin are given because they can cross the BBB! (cefotaxime 2 g qds or ceftriaxone 2 g bd). The reason is that Benzylpenicillin may be given as initial blind therapy and for sensitive meningococci and pneumococi.
Amoxicillin þ gentamicin for Listeria .
For penicillin and cephalosporin resistant pneumococci: add vancomycin and if necessary rifampicin.
If there is history of anaphylaxis to penicillin or cephalosporins or if the organism is resistant to these, use chloramphenicol.
Give rifampicin for 2 days to patients treated with benzylpenicillin or chloramphenicol (to eliminate nasopharyngeal carriage).
DEXAMETHASONE:
IV (10 mg QDS for 4 days) given shortly before or with first dose of antibiotics. Continue in pneumococcal or H. influenzae meningitis: reduced complications: death ( S. pneumoniae ) and hearing loss ( H. influenza ). Avoid dexamethasone if HIV is suspected.
RESUSCITATION: best managed in ITU
PREVENTION: (only applicable to meningococcal meningitis): Notify public health services and consult a consultant in communicable disease control for advice regarding chemoprophylaxis (e.g. rifampicin for 2 days) and vaccination for close contacts. Vaccination against meningococcal serogroups A and C. (Note that there is no vaccine for serogroup B, the most common serological group
Identify the possible complications of meningitis and its management
Sensorineural deafness is most common
Subdural effusions occur secondary to Haemophilus influenzae meningitis and may progress to a subdural empyema.
.Septicaemia, shock, DIC, renal failure, fits, peripheral gangrene, cerebral oedema, cranial nerve lesions, cerebral venous thrombosis, hydrocephalus, Waterhouse– Friderichsen syndrome (bilateral adrenal haemorrhage).
Summarise the prognosis for patients with meningitis
Mortality rate from bacterial meningitis is high (10– 40% with meningococcal sepsis). In developing countries mortality rate often higher. Viral meningitis self-limiting.
What is aseptic meningitis
This is when the meningitis is caused by either viruses, mycobacteria (e.g. TB), fungi or parasites
Because routine bacterial cultures of the CSF will be -ve in these cases.
Note that bacterial meningitis is NOT aseptic
How can you distinguish pure encephalitis from meningitis
Abnormal brain function in pure encephalitis but not meningitis
Meningeal irritation symptoms (such as neck rigidity) in meningitis but not pure encephalitis
Seizures in both.
Note that meningeal irritation symptoms may occur in meningoencephalitis
Petechiae would point towards which kind of meningitis
Neisseria meningitidis
Red maculopapular rash on wrists and ankles would point towards which kind of meningitis
Rock mountain spotted fever
The following features point towards which kind of meningitis:
Bull’s eye rash (erythema chronicum migrans)
Bilateral facial nerve palsy
Cardiac arrhythmias
Lyme disease meningitis
Flaccid paralysis of the extremeties is charactersitc of what kind of meningitis
West nile virus
Parotitis is suggestive of which kind of meningitis
Mumps
What kind of things would prompt suspicion of TB meningitis
If they also had pulmonary infiltrates, lymphadenopathy and a +ve tuberculin skin test
What would lead you to add IV acyclovir onto empiric Abx in a meningitis patient
If individual has features of encephalitis: abnornal brain function, fussiness or lethargy in infants, temporal lobe enhancement on CT
Crucial to NOT DELAY acyclovir if HSV enceph is a possibility
TB meningitis often involves which part of the brain
The brainstem
Discuss the levels of protein compared to normal (15-20 mg/dL) in the CSF in:
Bacterial, viral, fungal and TB meningitis
Bacterial 100-500
Viral 15-200
Fungal 15-200
TB 100-500
Bacteria and TB cause higher levels of protein in the CSF because they cause more inflammation, which increases the permeability of the BBB more than the other causes of meningitis, allowing more protein in
Discuss the level of glucose in the CSF, and the glucose CSF:serum ration in bacterial vs viral vs fungi meningitis and why
In bacterial/fungi the glucose will be reduced, but in viral it will be normal
This is because bacterial/fungal inflammation causes less gluocse to enter through the BBB as it blocks the glucose transporters
What is the diagnostic method for TB meningitis
TB PCR preferred because it is more sensitive and faster
Looking for AFB on microscope takes weeks and is low yield
What is the cryptococal meningitis diagnostic method
India ink stain showing broad budding yeast and a thick fungal capsule that does not take up the stain
The cryptococcal capsular antigen test is more sensitive and more commonly used
What coccidoidal meningitis diagnostic method
Small spherules on microscopic examination
but serum serology is now mainstay
Presecnce of what in the CSF suggests herpes simplex encaphalitis
Presence of RBCs
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Define Bell’s palsy
Course of the facial nerve
Functions of the facial nerve
Weakness or paralysis of the muscles on one side of the face, caused by damage to the seventh cranial nerve, which is the facial nerve
The seventh cranial nerve, the facial nerve, emerges from the brainstem, and then enters the temporal bone where it travels through a narrow, Z-shaped canal, called the facial canal.
The facial nerve exits the skull through a tiny hole called the stylomastoid foramen.
- Innervates facial muscles
- Innervates the sublingual and submandibular glands, which secrete saliva, the lacrimal gland which produces tears, and mucous membranes of the nose, mouth, and nasopharynx.
- it innervates the stapedius muscle which dampens the vibration of the stapes, a small bone that help transmit vibrations from the eardrum; this protects you from loud noises.
- carries sensory information about taste from the anterior ⅔ of the tongue.
Explain the aetiology / risk factors of Bell’s palsy
The underlying cause of cranial nerve damage is idiopathic which means it’s unknown, so when there’s facial nerve a paralysis from a known cause like a stroke, a tumor, or trauma, it’s not considered a Bell’s palsy.
Bell’s palsy occurs when the facial nerve gets damaged, and although the precise cause is unknown, it’s often associated with viral infections like:
- herpes simplex virus,
- Epstein-Barr virus, and varicella-zoster virus
- the bacteria Borrelia burgdorferi which causes lyme disease.
RISK FACTORS:
Age (peak incidence > 50), diabetes mellitus, pregnancy (third trimester), early postpartum
Summarise the epidemiology of Bell’s palsy
.
Recognise the presenting symptoms of Bell’s palsy
Unilateral facial weakness (evolves rapidly over 48hr)
Absence of nasolabial fold
Drooping of eyelid
Drooping of mouth
Dryness of affected eye/mouth
Hypersensitivity to loud noises (hyperacusis)
Loss of taste sensation on anterior 2/3 of tongue (ageusia)
(relate all of these to the function of the facial nerve)
Recognise the signs of Bell’s palsy on physical examination
mnemonic
Unilateral facial weakness (evolves rapidly over 48hr)
Absence of nasolabial fold
Drooping of eyelid
Drooping of mouth
Dryness of affected eye/mouth
Hypersensitivity to loud noises (hyperacusis)
Loss of taste sensation on anterior 2/3 of tongue (ageusia)
(relate all of these to the function of the facial nerve)
Mnemonic: Blink reflex abnormal Ear sensitivity Lacrimation: deficient, excess Loss of taste, Sudden onset Palsy: CN VII nerve muscles (all symptoms unilateral)
Identify appropriate investigations for Bell’s palsy and interpret the results
Lab: serological testing if viral infection suspected
Motor nerve conduction studies can be performed if there is no recovery after a few weeks to assess for the presence of axonal degeneration
Others:
House-brackmann facial nerve dysfunction classification
Palpebral-oculogyric reflex (Bell phenomenon): attempted eyelid closure –>upward eye deviation
Reduced pinprick sensation in posterior auricular area
Reduced taste
The diagnosis of a Bell’s palsy is based on identifying that the problem is with the facial nerve and not finding an alternative explanation like a stroke or brain tumor.
Generate a management plan for Bell’s palsy
Treatment isn’t needed in all cases of Bell’s palsy, but in some severe cases, corticosteroids can help reduce the nerve inflammation and speed up the recovery.
In most cases, symptoms usually subside on their own
Other: artifical tears, eye patching (reduce corneal damage risk), physical therapy (facial exercise, NM retraining)
Identify the possible complications of Bell’s palsy and its management
Permanent facial weakness or paralysis
You might get severe ectropian requiring partial lidsuturing
Summarise the prognosis for patients with Bell’s palsy
Most people recover within 6 months after the onset, but some people develop permanent facial weakness or paralysis.
Most patients with partial paralysis recover completely and rapidly, although in those with complete paralysis recovery may not occur until after 3 months. Recovery may be incomplete and in some patients with axonal degeneration abnormal reconnections may occur e.g. production of tears on eating. Surgery should not be considered until time for recovery (> 3 months) has been allowed.
How would you differentiate stroke from bell’s palsy with regard to facial weakness.
Explain this
The lower motor neurons innervating the bottom half of the face receive innervation from upper motor neurons originating on the contralateral side
The lower motor neurons innervating the top half of the face receive innervation from upper motor neurons originating on both the ipsilateral and the contralateral side (i.e. they have dual innervation)
Thus, in a stroke (affecting the upper motor neurons), the top half of the face will be spared, because the stroke will only affect one side of the brain, but the lower motor neurons for the top half of the face receive dual innervation, so they will still receive innervation from the upper motor neuron not affected by the stroke
HOWEVER,
In Bell’s palsy, there is a disease of the LOWER motor neuron so although both the ipsilateral and contralateral supply to the lower motor neuron is fine, the damage to the lower motor neuron itself means that the muscles in the top half of the face will be paralysed
Define multiple sclerosis
4 types (one doesn’t qualify as MS)
Autoimmune condition where inflammatory plaques of demyelination in the cns disseminated in space and time;
ie occuring at multiple sites, with ≥30d in between attacks
Demyelination heals poorly, eventually causing axonal loss; >80% of patients develop progressive disability.
- Relapsing, remitting (commonest. Complete recovery in between attacks)
- Clinically isolated syndrome (single clinical attack of demyelination. Not actually MS, but 10-15% develop it after)
- Primary progressive MS (steadily accumulation of disability with no relapsing-remitting pattern)
- Secondary progressive:
Symptoms worsen more steadily over time, with or without the occurrence of relapses and remissions. Most people who are diagnosed with relapsing-remitting multiple sclerosis will transition to SPMS at some point (due to poor axonal healing) - Marburg variant (severe filminant variant of MS leading to advanced disability or death within a period of weeks)
Explain the aetiology / risk factors of multiple sclerosis
The exact cause of the disease remains unknown; it is most likely a combination of genetic and environmental factors.
Immune-mediated damage to CNS myelin results in impaired conduction along axons. There is also associated grey matter atrophy.
Type IV hypersensitivity reaction! T cells attacking myelin. This then causes antibody reaction to myelin and cell mediated attack of oligodendrocytes.
Leaves behind plaques.
Risk factors:
-Role for EBV exposure and prenatal vitamin D levels have been proposed based on epidemiological studies.
- Strong concordance in monozygotic versus dizygotic twins (25% vs 3%).
- HLA-DR 2
- Geographical variation (temperate > tropical) with individuals carrying the risk of their pre-pubertal ( < 13 years) country of origin.
Summarise the epidemiology of multiple sclerosis
Mean age of onset is 30yrs. ♀:♂ ≥3:1.
Rare in tropical countries
Recognise the presenting symptoms of multiple sclerosis
Depends on site of inflammation
- Optic neuritis (commonest)- unilatral deterioration in visual acuity and colour perception + PAIN on eye movement
- Sensory system: Pins and needles, numbness, burning.
- Motor: Limb weakness, spasms, stiffness, heaviness.
- Autonomic: Urinary urgency, hesitancy, incontinence, impotence.
- Psychological: Depression, psychosis.
Uhthoff’s phenomenon: Transient increase or recurrence of symptoms due to conduction block precipitated by a rise in body temperature. (body gets overheated from hot weather, exercise, fever, or saunas and hot tubs!)
Recognise the signs of multiple sclerosis on physical examination
What would fundoscopy show in active vs chronic disease
Which structure is likely to be affected in each case:
- Central scotoma
- Field defects
CLASSICALLY: CHARCOT’S NEUROLOGIC TRIAD:
1) Dysarthria (difficult/unclear speech and swallowing)
2) Nystagmus (involuntary rapid eye movements) + plaques in the eyes
3) Intention tremor (plaques along motor pathways)
- Optic neuritis 1 : Impaired visual acuity (most common), loss of coloured vision. On fundoscopy, in active disease, there is a swollen optic nerve head, in chronic disease, there may be optic atrophy.
- Visual field testing: Central scotoma (optic nerve affected) or field defects (optic radiations affected).
- RAPD: Both pupils contract when light is shone on the unaffected side, both pupils dilate when light is swung to the diseased (eye).
- Internuclear opthalmoplegia: when trying to look horizontally, there is a failure of adduction of the contralteral eye, indicating a lesion of the contralateral MLF. https://www.youtube.com/watch?v=NAz_g3FDPjw
- Sensory: Paraesthesia (vibration and joint position sense loss more common than pain and temperature).
- Motor: UMN signs (e.g. spastic weakness, brisk reflexes).
- Cerebellar: Limb ataxia (intention tremor, past-pointing and dysmetria on finger-nose test and heel-shin test), dysdiadochokinesis, ataxic wide-based gait, scanning speech.
- Lhermitte’s phenomenon: Electric shock-like sensation in arms and legs precipitated by neck flexion.
Identify appropriate investigations for multiple sclerosis and interpret the results
Diagnosis based on two or more CNS lesions with corresponding symptoms, separated in time and space (McDonald criteria).
FIRST INVESTIGATION: MRI-brain, cervical and thoracic spine (with gadolinium contrast): Plaque detection is highlighted as high-signal lesions -“white matter plaques”.
This can monitor disease progression and help diagnosis
Lumbar puncture: Microscopy to exclude other infective or inflammatory causes. CSF electrophoresis shows unmatched oligoclonal bands. Their presence suggests inflammation of the central nervous system due to infection or another disease. If similar bands aren’t present in your blood, you may have multiple sclerosis (MS).
Evoked potentials: Visual, auditory or somatosensory evoked potentials (VEP, BEP, SEP) may show delayed conduction velocity. VEPs are delayed in ~90% of patients with MS.
Visual evoked potentials are used to investigate patients with no clinically obvious or acute optic neuritis who are suspected to have multiple sclerosis (MS), or when there is diagnostic uncertainty about the cause of visual loss. It gives an objective measure of visual pathway function.
What is todd’s paralysis. How to deal with it
Post-ictal neurologic dysfunction (i.e. dysfunction in the altered stage of consciousness following a seizure)
Affects same area of brain from which seizure originated ranging from motor, sensory or special sense dysfunction including speech, hearing and vision.
Todd’s paralysis usually affects the same areas in which the seizure originated. It can also affect speech, gaze, and vision.
It can later go through secondary generalisation (i.e. spread to rest of body).
Self-limited condition but can require work up for other causes of paralysis e.g. stroke
What is conversion disorder
Conversion disorder describes a condition of neurologic dysfunction with no identifiable organic cause.
What is malingering. How can you tell if a patient is malingering paralysis
Malingering is the deliberate feigning of symptoms to achieve secondary gain, such as a patient faking abdominal pain to receive a prescription for narcotic pain medications.
Patients who act paralyzed often display give-away weakness. This includes maintenance of strength for a brief period followed by voluntary muscle relaxation.
Status epilepticus. How long must the seizure have been going on for
Convulsive (i.e. includes marker motor symptoms e.g. tonic clonic movements) >5mins.
If non-convulsive, lasting >10 mins
What type of symptoms would you get from embolic stroke in:
anterior cerebral artery
middle cerebral artery
posterior cerebral artery
Anterior cerebral artery injury affects the sensory and motor cortices of the lower extremity, and results in contralateral paralysis and sensory loss of that limb only. It would not affect the face or upper extremity. Behavioural changes
Middle cerebral artery
- affects the sensory and motor cortices of the face> upper extremity> leg
- Broca area, and Wernicke area so problems with speech fluency/language comprehension problem
- loss of contralateral half of visual field
PCA strokes like diplopia, visual field defects, dysphagia, vertigo, alteration in consciousness, memory impairment, or difficulty reading
T/F in expressive aphasia, the patient’s comprehension will be completely fine
F… Comprehension is mildly to moderately impaired in expressive aphasia.
What is:
Global aphasia
Anomic aphasia
Conductive aphasia
Global aphasia is a severe impairment of both expressive and receptive skills. It is caused by a large left hemisphere lesion. People are often alert and are able to express themselves through facial expressions, intonation, and gestures.
Anomic aphasia is a mild form of aphasia. The most prominent difficulty is in word-finding, with the person using generic fillers in utterances, such as nonspecific nouns and pronouns, or circumlocution, where the person describes the intended word. Comprehension and repetition of words, and sentences is typically good.
Conductive aphasia is characterized by prominent impairment with repetition. Damage typically involves the arcuate fasciculus and the left parietal region. The patient is able to express him- or herself fairly well, with some word-finding issues, and comprehension can be functional.
Anterior spinal cord syndrome would lead to what picture
Knowledge of this syndrome relies on the neuroanatomic knowledge of the cross-sectional spinal cord tract pathways:
- pain/temperature via spinothalamic tract,
- motor via corticospinal tracts, and
- tactile/vibration sensation via dorsal column medial lemniscus (DCML) tracts.
ACS leads to ischemia of the former two anteriorly located tracts, with preservation of the DCML tract, as supplied by the posterior spinal artery.
Presents with bilateral motor and temperature/pain sensory deficits, with intact pinpoint and vibratory sensation due to the preserved dorsal DCML pathways.
Differentiate the neurologic defecits caused by b12 and folate deficieny
Whereas B12 deficiency will have loss of proprioception, folate deficiency will not have any neurologic dysfunction.
This is because Vitamin B12 deficiency can lead to an accumulation of methylmalonic acid which causes dysfunction of the dorsal columns and lateral corticospinal tract. This relatively rare symptom is known as subacute combined degeneration. These patients will have ataxia and loss of proprioception.
Note that b12 deficiency will also lead to macrocytic and megaloblasic anaemia
Define Parkinson’s disease
Neurodegenerative disease of the dopaminergic neurones of the substantia nigra (which project to the striatum), characterized by bradykinesia, rigidity, tremor and postural instability (a late symptom).
Explain the aetiology / risk factors of Parkinson’s disease
What do neurons affected by parkinsons show before they die
What % of neurones need to be affected before symptoms arise
Pathophysiology:
-Degeneration of midbrain dopaminergic neurones projecting from the substantia nigra to the striatum (caudate nucleus and putamen).
Surviving neurones often contain eosinophilic cytoplasmic inclusions called Lewy bodies (Lewy bodies are eosinophilic, made of alpha synuclein proteins).
Patients only symptomatic after > 70% neuronal loss. Nigrostriatal dopaminergic deficiency causes abnormalities of plasticity in the basal ganglia and cerebral cortex.
1) Sporadic and idiopathic (most common) : Unknown. Environmental toxins and oxidative stress have been proposed (e.g. pesticides, wood pulp).
2) Familial forms :
- Genes mutations that cause Parkinson’s Disease are in LRRK2, PARK2 (Parkin), PARK7, PINK1 and SNCA ( a -synuclein) genes.
PINK1, PARKIN, ALPHA SYNUCLEIN genes
3) IN RARE CASES: A toxic impurity cound in recreational drugs (especially MPPP). The impurity is called MPTP
Risk factors:
Pesticide exposure
Gene variants LRRK2
Summarise the epidemiology of Parkinson’s disease
.Very common: 1– 2% of > 60-year-olds. Annual incidence is 20 in 100000. Mean age of onset is ~ 57 years.
Recognise the presenting symptoms of Parkinson’s disease
Is the tremor unilateral or bilateral?
How do you distinguish this tremor from benign essential tremor?
HISTORY:
Insidious onset.
Tremor AT REST, usually noticed in hands (most present with unilateral UL tremor, this later spreads to involve other limbs). (an intention or action tremor is seen in Benign Essential Tremor, so ensure you distinguish this from Parkinson’s)
Stiffness and slowness of movements
Difficulty initiating movements
Frequent falls
Smaller handwriting (micrographia)
Insomnia, mental slowness (bradyphenia)
NARROW gait
Recognise the signs of Parkinson’s disease on physical examination
Pill rolling tremor at rest
Lead pipe rigidity of muscle tone with superimposed tremor (cogwheel rigidity), which can be enhanced by distraction (asking them to raise and lower other arm)
Gait: stooped, simian, shuffling, small-stepped fait with reduced arm swing. Freezing (difficulty initiating walking)
Postural instability: falls easilty with little pressure from back (propulsion) or front (retropulsion)
Others:
- Frontalis overactivation (furrowing of brow)
- Hypomimia (expressionless face)
- Soft monotonous voice (hypophonia)
- Impaired olfaction
- Mild impairment of up-gaze and tendency to drool
- Involuntary movements in one part of the face associated with voluntary movement in another part of the face (synkinesis)
Psych: depression common. Cognitive problems and dementia in late disease
Identify appropriate investigations for Parkinson’s disease and interpret the results
How would y ou distinguish from essential tremor
Clinical diagnosis:
- Levadopa trial and clinical assessment after levodopa
- Blood: Serum ceruloplasmin excludes WILSON’S disease in young onset
- CT/MRI brain to exclude other causes of gait decline e.g. hydrocephalus, vascular disease
- Dopamine transporter scintigraphy (DAT scan): reduction in striatum and putamen. May be necessary for distinguishing from essential tremor.
How many substantia nigra in the brain
2- one on each side of the midbrain
Where do dopaminergic neurons in the nigrostriatal pathway
This is the one affected in parkinson’s.
They go from the substantia nigra, which is in the basal ganglia, up to the striatum (=caudate + putamen) in the motor cortex
Which part of the substantia nigra is affected in parkisons
pars compacta
In parkinson’s there is a resting tremor, what does this mean
There is a tremor present at rest which DIMINISHES with movement
T/F Parkinson’s disease causes weakness
NO!!!!!
This helps differentiate it from other diseases
How might you distinguish parkinsons from cerebellar diseases
Because cerebellar disease have action (=intention) tremor, which is the opposite of the resting tremor seen in parkinson’s
How might you distinguish parkinson’s from essential tremor
In essential tremor there is no bradykinesia, or postural instability
Note that in Parkinson’s there is NO WEAKNESS.
Outline causes of parkinsonism
Idiopathic Parkinson’s disease
Side effects of medication:
- Antipsychotics (haloperidol, blocking dopamine receptors)
- Metaclopramide (dopamine antagonist)
Rarely: trauma/boxing, encephalopathy post flu, manganese/copper toxicity, HIV, parkinson’s plus syndromes
Parkinson’s plus syndromes:
Lewy body dementia
Wilson disease
Pick disease (a type of fronto-temporal dementia
What are your red flag signs for parkinson’s plus and why
VIVID
V- vertical gaze palsy and early postural instability (this is usually a late feature if it’s PD)–> progressive supranuclear palsy
I- Impotence/incontinence –> multiple system atrophy
V- Visual hallucinations and early dementia–> lewy body dementia
I-Autonomous interfering activity by affected limb–> corticobasal degeneration
D-diabetic/hypertensive patient with pyramidal signs (leg) and falls, ataxia –> vascular parkinsonism
Non-motor features of parkinsonism
Loss of smell Depression and dementia Visual hallucinations Dribbling of saliva Constipation
Define hydrocephalus
Enlargement of the ventricular system in the brain caused by impaired drainage of cerebro-spinal fluid
Explain the aetiology / risk factors of hydrocephalus
Divisible into obstructive and npn-obstructive (communicating and non-communicating)
Communicating= impaired outflow of the CSF from the ventricular system:
- Lesions of 3rd, 4th ventricle or aqueduct
- Posterior fossa lesions compressing 4th ventricle (e.g tumour blood)
- Cerebral aqueduct stenosis
Non communicating= impaired CSF resorption in the subarachnoid villi:
- Tumours
- Meningitis (typically TB)
- Normal pressure hydrocephalus (see below)
Summarise the epidemiology of hydrocephalus
Bimodal age distribution. Congenital malformations and tumours in the young, tumours and strokes in the elderly.
Recognise the presenting symptoms of hydrocephalus
What about normal pressure hydrocephalus specifically?
Obstructive hydrocephalus : Headaches. Vomiting. Seizures. Acute drop in conscious level. Balance problems. Diplopia.
NPH : Chronic cognitive decline, falls, urinary incontinence.
Recognise the signs of hydrocephalus on physical examination
In neonates?
NPH?
Obstructive hydrocephalus : Impaired GCS, papilloedema, VI nerve palsy (“false localizing” sign of increased ICP). In neonates, the head circumference may enlarge, and “sunset sign” (downward conjugate deviation of eyes). In children, enlarged head, developmental delay, intellectual disability, muscle spasticity
NPH : Cognitive impairment. Gait apraxia (shuffling). Hyper-reflexia.
Identify appropriate investigations for hydrocephalus and interpret the results
CT head : First-line investigation to detect hydrocephalus. May also detect the cause (e.g. tumour in the brainstem).
CSF : Obtained from ventricular drains or lumbar puncture may indicate an underlying pathology (e.g. tuberculosis). Check for MC&S, protein, glucose (CSF and plasma).
The best way to diagnose aqueduct stenosis is with an MRI because it can visualise the entire length of the aqueduct
Lumbar puncture : This is contra-indicated in obstructive hydrocephalus as it can cause tonsilar herniation and death. May be necessary in NPH as a therapeutic trial.
What is hydrocephalus ex vacuo
Term used to describe apparent enlargement of ventricles but this is a compensatory change due to brain atrophy
What is normal pressure hydrocephalus.
What are the signs
A type of non communicating hydrocephalus.
Idiopathic chronic ventricular enlargement. The long white matter tracts (corona radiata, anterior commisure) are damaged causing gait and cognitive decline.
Hydrocephalus treatment?
Manage emergencies with ABC, and manage seizures
Surgical insertion of a ventriculoperitoneal shunt. Helps to reduce ICP. Implantation of a ventricular catheter into one or both lateral ventricles and connecting it to a subcutaneous drain which leads to the peritoneal cavity. Carries risk of shunt infection, block or malfunction (especially as some are electronic).
Lumbar-peritoneal shunting : Alternative procedure that may be suitable for communicating hydrocephalus. Advanced neurosurgery : Endoscopic ventriculostomy and aqueductoplasty are other options used to bypass blockages or maintain patency for CSF flow.
Also physiotherapy to help develop motor skills
Define epilepsy
Classification of epilepsy
At a basic level, what is more likely to be the cause of each type.
Which is more likely to be preceded by an aura
Chronic neurological condition with recurrent seizures
> 2 seizures REQUIRED for diagnosis
Partial (=focal):
- One hemisphere affected.
- More likely to be due to a structural abnormality
- Preceded by aura
e. g. Frontal lobe focal motor seizure, temporal lobe seizures, frontal lobe complex partial seizures
Partial seizures are usually “simple” (i.e. awareness not impaired, no post-ictal symptoms, auras present), but can also be “complex” (i.e. awareness impaired, post-ictal confusion common, may have auras). Can also undergo secondary generalisation.
Generalised:
- Both hemispheres
- LOC occurs
- More likely idiopathic/congenital
e. g. Tonic, clonic, tonic-clonic, atonic, myoclonic, absence,
Explain the aetiology / risk factors of epilepsy
Classify into provoked (acute symptomatic) seizures (INVITED MD), and unprovoked seizures (which can occur due to a genetic problem, or a metabolic/structural abnormality)
- Family Hx
- Febrile convulsions
- Autism/ADHA
- Cerebral palsy/stroke
CAUSES:
Idiopathic- 2/3
Infection: meningitis/encephalitis/abscess (including scarring from previously having these infections)
Neoplasm: Tumour
Vascular: stroke, haemorrhage, malignant hypertension or eclampsia
Inflammation: SLE, PAN, rarely MS
Toxic/metabolic: sodium imbalance, hyper- or hypoglycaemia, hypocalcaemia, hypoxia, prophyria, liver failure)
E-
Drugs, including withdrawal from alcohol and benzos)
Metabolic above
Degenerative: Alzheimer’s disease
PATHO:
Epislepsy results from an imbalance in the inhibitory and excitatory currents (e.g. Na þ or K þ ion channels) or neurotransmission (i.e. glutamate or GABA neurotransmitters) in the brain. Precipitants include any trigger which promotes excitation of the cerebral cortex (e.g. flashing lights, drugs, sleep deprivation, metabolic), but often cryptogenic.
Summarise the epidemiology of epilepsy
Common. Prevalence in 1% of general population. Peak age of onset is in early childhood or in the elderly.
Recognise the presenting symptoms of epilepsy
general seizure history questions, see below for in depth history for each type
History:
- Rapidity of onset
- Duration
- Aura (in focal epilepsy)
- Tongue biting/loss of continence
- Alteration of consciousness
- Trigger? Lack of sleep, stress
- Did anybody witness
- Jerking?
- Posticteral state of reduced consciousness?
- Drug Hx
Recognise the signs of epilepsy on physical examination
Depends on aetiology, usually normal between seizures. Look for focal abnormalities indicative of brain lesions.
Identify appropriate investigations for epilepsy and interpret the results
Blood: FBC, U&E, LFTs, glucose, Ca 2+ , Mg 2+, prolactin (transient increase shortly after a “true” seizure).
ECG
CT/MRI: For structural, space-occupying and vascular lesions.
EEG (supportive): Helps confirm or refute the diagnosis; assists in classifying the epileptic syndrome. Usually performed inter-ictally and often normal and does not rule out epilepsy. Ictal EEGs combined with video telemetry are more useful but requires adequate facilities.
Other investigations: Particularly for secondary seizures according to suspected aetiology e.g. lumbar puncture, HIV serology. , ABG, toxicology screen,
Generate a management plan for epilepsy
(see management of status epilepticus below)
What are the contraindications for each of the following AEDs:
- Carbamazepine
- Valproate
Which drug is to be used in seizures for pregnant women
Conservative:
- Check time (call ambulance if >5 minutes)
- Protect head and loosen tight clothing.
- DON’T hold them down, put anything in their mouth, move them unless in danger
- Put them in recovery position and minimise their embarrassment (hide incontinence) after
Pharmacological:
-Basic: carbamazepine/lamotrigine for partial seizures, valproate for generalised
Partial seizures (+/- secondary generalisation):
- Carbamazepine, lamotrigine (1st line)
- Valproate (2nd line)
CLV–>VLC
Tonic-clonic:
- Valproate, lamotrigine (1st line)
- Carbamazepine, topiramate (2nd line)
Myoclonic, tonic, atonic:
Same as tonic-clonic but avoiding carbamazepine
Absences:
- Valproate, ethosuximide (1st line)
- Lamotrigine (2nd line)
Contraindications:
Carbamazepine: Not to be prescribed if on oral contraceptive pill
Valproate: Highly teratogenic, avoid in women of child bearing age
Lamotrigine: 1st line for pregnant women
Identify the possible complications of epilepsy (incl. status epilepticus) and its management
Complications of epilepsy:
-Long seizures can lead to hypoxic brain injury
Complications of epilepsy management:
Antiepileptic drugs, particualry ethosuximide, lamotrigine, carbamezapine, phenytoin, phenobarbital and valproate are notorious for causing skin reactions.
Anticonvulsant Hypersensitivity Syndrome occurs in some patients taking anticonvulsant medication. It is characterised by fever, rash, hepatitis and other multiorgan abnormalities. They should not receive should not receive anticonvulsants in the phenytoin category, carbamazepine, phenobarbitone and lamotrigine.
Summarise the prognosis for patients with epilepsy
.
What is the most common site of a partial (=focal) seizure.
What is the most common cause of these seizures.
Presentation of temporal lobe seizure?
TEMPORAL LOBE FOCAL SEIZURE
Most common cause=hippocampal sclerosis
Auras:
- De ja vu, ja me vu
- Olfactory/gustatory hallucination
- Auditory hallucinations
- Feelings of panic and anger
- Memory loss
- Dysphasia
- Automatisms (lip smacking, chewing, fidgeting etc.)
Presentation of frontal lobe focal motor seizure?
This is a type of simple partial seizure
Frontal lobe focal motor seizure:
-Motor convulsions, may demonstrate Jacksonian march (spasm spreading from mouth or digit) followed by post-ictal flaccid weakness (Todd’s paralysis)
Presentation of a frontal complex partial seizure
Loss of consciousness with associated automatisms and rapid recovery.
Presentation of tonic-clonic (grand mal) seizure.
Is there post ictal?
This a generalised seizure.
Vague symptoms before an attack (e.g. irritability), followed by tonic phase (generalised muscle spasm), followed by a clonic phase (repetitive synchronous jerks), and associated faecal or urinary incontinence, tongue biting. After a seizure, there is often impaired consciousness, lethargy, confusion, headache, back pain, stiffness.
Presentation of absence seizure (petit mal) seizure
Is there post ictal?
Usual onset in childhood. Characterized by loss of consciousness but maintained posture (patient stops talking and stares into space for seconds), blinking or rolling up of eyes with other repetitive motor actions (e.g. chewing).
No postictal phase.
Presentation of non-convulsive status epilepticus
Acute confusional state. Often fluctuating. Difficult to distinguish from dementia.
Management of status epilepticus. What is status epilepticus
Status epilepticus >30 mins and failure to regain conscioussness (but treatment often initiated in 5-10 mins) :
- Secure airway and recovery position
- o2
- IV access
- IV benzodiazepine: lorazepam (or buccal midazolam/rectal diazepam) given over 2 minutes
- Repeat after 15 minutes if necessary
- If recur/fail to respond, IV anticonvulsant needed: e.g. phenytoin (15mg/kg) under ECG monitoring. Alternatively, give phenobarbitone, levetiracetam or sodium valproate.
- If these fail, consider general anaesthesia, requiring intubation and mechanical ventilcaiton
- Treat cause (correct hypoglycaemia or hyponatraemia)
- Check plasma levels of all anticonvulsants
MOA and side effects of each of the following anticonvulsants:
Carbamazepine Phenytoin Lamotrigine Ethosuzimide Valproate Topiramate Levetiracetam
What about interactions
Carbamazepine (Na+ channel blocker, extends inactivation)- Hyponatraemia. CI: oral contraceptive pill.
Phenytoin (Na+ blocker) : bone mineralisation, gingial hyperplasia
Lamotrigine (Na+ channel blocker, selective for excitatory NT like glutatmate)- stevens-johnson syndrome
Ethosuximide (Ca2+ channel blocker, thalamic)- sedation
Valproate (many: blocks Na, enhance GABA, block Ca) - foetal malormation
Topiramate (blocks Na, enhances GABA, blocks NMDA) - cognitive impairment/weight loss kidney stones
Levetiracetam (unknown): depression/behavioural/psych issues
Carbamazepine, phenytoin, phenobarbitol all p450 inducers
Valproate is a p450 inhibitor
What is the usual cause of a subarachnoid haemorrhage
What are the signs and symptoms
This may occur spontaneously, usually from a ruptured cerebral aneurysm, or may result from head injury.
igns and symptoms of SAH include a severe headache with a rapid onset (“thunderclap headache”), vomiting, confusion or a lowered level of consciousness, and sometimes seizures.
What does CT and LP show for SAH
You need to do CT-scan first.
If this has been ruled negative and there are no clinical signs of increased intracranial pressure, a lumbar puncture is the next step in the work-up.
In a CT scan with findings due to SAH, you would see blood pooling in the cisterns.
On LP the fluid looks yellow due to xanthochromia (presence of oxidized RBCs)
`Define subarachnoid haemorrhage
An arterial bleed into the space between the arachnoid and pia mater of the meninges
Explain the aetiology / risk factors of subarachnoid haemorrhage
Specifically what are the associations too
85%: burst saccular aneurys in circle of willis
5%: perimesencephalic haemorrhage (parenchymal hammorhage tracking to surface of prain)
5%: AV malformations, bleeding diatheses, vertbral/carotid artery dissection with intracranial extension/mycotic aneurysm/drug abuse (cocaine and amphetamine)
ASSOCIATIONS:
- HTN, smoking, excess EtOH, SACCULAR ANEURYSMS ASSOCIATED WITH PCKD, marfans, pseudoxanthoma elasticum and Ehlers Danlos syndrome
Head trauma
Summarise the epidemiology of subarachnoid haemorrhage
Peak in 5th decade
Recognise the presenting symptoms of subarachnoid haemorrhage
Sudden onset, thunderclap headache (back of head).
Nausea, vomiting, neck stiffness, photophobia
Reduced consciousness
Subarachnoid hemorrhage
(SAH) patients will commonly report having another sudden, severe
headache
one to three weeks prior. These are known as “sentinel
headaches
“ and are thought to be caused by a minor hemorrhage.
Recognise the signs of subarachnoid haemorrhage on physical examination
Meningism (blood irritates the meninges):
- Neck stiffness,
- Photophobia
- Kernig’s sign
Pyrexia
Assess GCS
Signs of high ICP:
- Hypertension with bradycardia
- Papilloedema,
- Cranial nerve palsy (IV or III)
Fundoscopy: Rarely subhyaloid haemorrhage between retina and vitreous membrane
Focal neurological signs:
-Usually develop on 2nd day, caused by ischaemia from vasospasm and reduced brain perfusion. Aneurysms may cause pressure on cranial nerves causing opthalmoplegia (classically III or VI nerve palsy)
Identify appropriate investigations for subarachnoid haemorrhage and interpret the results
Bloods: FBC, U&E, ESR/CRP, clotting (bleeding diathesis?)
Non contrast CT scan: hyperdense areas in the basal regions of the skul caused by blood in the SAH space). Identifies any intraparencymal or intraventricular haemorrhagegs as well
LP: increased opening pressure, increased red cells, few white cells, xanthochromia (confirmed by spectrophotometry of CSF supernatant after centrifugation)
Symptoms resulting from an aneurysm in the right carotid artery?
How would you distinguish that from a pituitary adenoma
An aneurysm of the right carotid artery would cause cavernous sinus syndrome and could produce the symptoms related to compression of CN III, IV, VI, V1 and V2. However, the hormonal changes cannot be attributed to an aneurysm of this blood vessel.
Symptoms of idiopathic intracranial hypertension, and who is it most common in
Pseudotumor cerebri is a condition characterized by headaches behind the eye. It is most common in obese women, but typically presents with dizziness, nausea and vomiting. The vision loss associated is usually brief, unlike the long-lasting vision loss experienced by the patient.
Define Wernicke’s encephalopathy
Condition by confusion, ataxia and opthalmoplegia
Explain the aetiology / risk factors of Wernicke’s encephalopathy
What does it usually do?
Happens because of the neurological effects of b1 (thiamine) deficiency
1) It is a coenzyme for important enzymes in glucose metabolism
2) In the brain it helps metabolise lipids and carbohydrates and maintain normal AA and neurotransmitter levels
3) In some neurons helps propogate neural impulses down the axon
Specifically, thiamine deficiency impairs glucose metabolism and this leads to a decrease in cellular energy.
The brain is particularly vulnerable to impaired glucose metabolism since it utilizes so much energy.
Differentiate wernicke’s encephalopahty with korsakoff psychosis
Wernicke’s encephalopathy is nystagmus, ophthalmoplaegia and ataxia, together with apathy, disorientation and disturbed memory. Treat urgently with thiamine or may progress to Korsakoff ‘s psychosis.
Korsakoff’s psychosis is characterized by profound impairment of retrograde and anterograde memory with confabulation, as a result of damage to the mammillary bodies and the hippocampus. Irreversible.
How does excess alcohol intake lead to wenicke-korsakoff syndrome
1) First, alcohol interferes with the conversion of thiamine to its active form, thiamine pyrophosphate by blocking the phosphorylation of thiamine.
2) Second, thiamine is normally absorbed through the first portion of the small intestine called the duodenum.
However, ethanol prevents this absorption process, and it is believed that alcohol does this by reducing the gene expression for thiamine transporter-1 within the intestinal brush border.
3) Third, chronic alcohol abuse can lead to fatty liver or cirrhosis which interferes with the storage of thiamine within the liver.
Signs and symptoms of wernicke’s-korsakoff syndrome
Early on in thiamine deficiency, the cerebellum gets affected and that can affect movement and balance.
In addition, the brainstem can be affected, and that’s the region that gives rise to the cranial nerves that provide motor and sensory innervation to the face and eyes.
If the medulla region of the brainstem is affected, it can impair the heart rate and breathing.
Later findings in thiamine deficiency are hemorrhage and necrosis of the mammillary bodies.
Wernicke’s encephalopathy is characterized by ophthalmoplegia, meaning weakness or paralysis of the eye muscles, ataxia or unsteady gait, and changes in mental state like confusion, apathy, and difficulty concentrating.
And untreated Wernicke’s encephalopathy can lead to coma and death if not treated quickly.
Korsakoff syndrome, on the other hand, mainly targets the limbic system, causing severe memory impairment.
One of the characteristic findings of Korsakoff syndrome is confabulation in which the person creates stories to fill in the gaps in their memory which they believe to be true. Not too different from what young children sometimes do in retelling a story.
How do you treat wernicke’s encephalopathy
The therapy is an infusion of thiamine over a few days to get rid of the deficiency.
This is then followed by glucose
Why don’t you give glucose before thiamine in the treatment of wernicke’s encephalopathy?
It’s important to normalize the thiamine levels first, because without thiamine pyrophosphate, most of the glucose will become lactic acid and that can lead to metabolic acidosis.
Drug used to treat partial seizures that has now caused morbiliform rash?
Lamotrigine
Why might you want to look at ESR in someone with TIA or stroke
Vasculitides can rarely cause TIA’s hence ESR estimation is useful
What investigations would be performed in someone who has had TIAs
This patient needs urgent investigation – usually involving carotid doppler ultrasound and CT/MR of the brain (to look for ischaemia, infarct, bleed, tumour)
T/F CT/MR angiography is not used in the initial investigation of a stroke
F…
CT/MR angiography can also be used to non-invasively image the carotid vessels. These techniques are usually used to further evaluate carotid stenoses identified with ultrasound.
Conventional angiography is invasive and with risk of stroke is now used less often!
Why is echocardiogram useful for stroke
Echocardiogram may also be helpful to assess cardiac function and also can identify mural thrombus/valvular disease/left atrial tumour which can all rarely cause TIA’s.
Echo cardiography may also be useful to assess left ventricular function as a marker of end organ damage secondary to hypertension.
What are the indications for carotid endarectomy
Carotid endarterectomy is generally used for patients fit enough to tolerate surgery, who have had a symptomatic TIA/ Stroke with good recovery in the previous 6 months, involving the anterior circulation.
Surgery is beneficial in patients with >70% stenosis and surgery itself is not without a small risk of stroke.
T/F absence of a carotid bruit excludes carotid stenosis
Absence of carotid bruit does not exclude a stenosis – indeed a critical stenosis may have almost no flow and bruit will be absent.
Which conditions can mimic a TIA
Hypoglycaemia, migraine, AF, glioma
Why are steroids given in the case of brain tumours
Steroids are indicated to reduce cerebral oedema around lesions.
What is the most sensitive way of assessing NM respiratory compromise
Spirometry
What type of respiratory failure is a patient with GBS likely to develop
In the context of GBS, the patient is likely to develop type 2 respiratory failure, with pCO2 rising early and pO2 falling later. Thus O2 saturations are not very sensitive. Imaging (CXR and CT chest) may show elevated diaphragms, basal atelectasis and be useful where secondary respiratory compromise through aspiration or PE is suspected.
How will you differentiate temporal arteritis from trigeminal neuralgia
Both can result in pain in in the temporal region, and be worsened by eating, talking, brushing hair.
Loss of vision is exclusive to temporal arteritis
In temporal artertitis the pain is constant and severe.
Trigeminal neuralgia causes intermittent, sharp pain, often in a mandibular/maxillary distribution. Pain can be worsened by eating, talking but is episodic and severe in nature. It is not associated with visual loss.
Trgeminal neuralgia is a symptom of MS!
How would you differentiate a 3rd nerve lesion from horner’s syndrome?
A lesion of the sympathetic chain causes a Horner’s syndrome with ptosis but does not affect eye movement.
3rd nerve lesion would cause ptosis and affect eye movement
Also, the ptosis in 3rd nerve palsy may be complete but in horner’s would be very subtle often
T/F: a 3rd nerve lesion can only cause a partial ptosis, but can cause a dilated pupil that is unreactive to light
F
A 3rd nerve lesion can cause COMPLETE ptosis AND a dilated pupil that isn’t reactive to light
