Neuroimmunology Flashcards
What is transverse myelitis?
Inflammation of the spinal cord - typically affecting a level
What’s the difference between myelitis and myelopathy?
Myelitis is the Inflammation of the spinal cord
Myelopathy is damage of the spinal cord
- Extrinsic or intrinsic
List causes of myelitis
1) Infection
- HSV, VZV, HTLV1, HIV, syphilis, TB, mycoplasma
2) Autoimmune
- MS, NMO, Sarcoid, GFAP
3) Paraneoplastic - CRMP5, amphiphysin
List causes of myelopathy - think extrinsic and intrinsic
1) Extrinsic
> Tumour
> Trauma
> Compression - disc herniation, epidural mets, epidural abscess
2) Intrinsic > Vascular - Cord infarct (anterior spinal artery) - Spinal dural AVF - Syrinx > Genetic - Hereditary spastic paraparesis - Leukodystrophies > Tumour > Nutritional - copper, B12, vitamin E > Drugs and toxins - nitric oxide
List primary causes of transverse myelitis
MS
Neuromyelitis optica (NMO)
Acute demyelinating encephalomyelitis (ADEM)
Post vaccine
List systemic causes of transverse myelitis
1) Systemic inflammatory conditions
SLE
Behcets
Sarcoid (Heerfordt syndrome)
2) Infectious
Syphilis, TB, HIV, HTLV1`, mycoplasma, HSV, VZV
3) Paraneoplastic - CRMP-5 ab, anti-amphyphysin ab
What’s Heerfordt syndrome?
Transverse myelitis secondary to sarcoid
Get facial palsy + uveitis + fever + parotid enlargement + transverse myelitis
How to differentiate between optic neuritis and optic neuropathy?
Both cause visual loss
Optic neuritis causes pain on eye movement
Optic neuropathy is painless
How does optic neuritis present?
Pain on eye movement
Decreased visual acuity and colour vision
Sparkles of light (photopsia)
Cecocentral scotoma (a central scotoma that joins up with a blind spot)
RAPD positive
Optic disc swelling if there is anterior inflammation of the optic nerve (comes out to make optic disc).
No optic nerve swelling if its retrobulbar inflammation (posterior section of optic nerve). Progresses to optic nerve disc pallor.
List causes of optic neuritis
1) Infection - Bartonella (cat scratch disease), syphilis
2) Autoimmune - MS, NMO, sarcoid
3) Paraneoplastic - CRMP 5
List causes of optic neuropathy
Think extrinsic and intrinsic
1) Extrinsic
- Compression by Tumour
- Compression by raised intracranial pressure (bilateral optic nerve compression)
- Trauma
2) Intrinsic
- Vascular - non-arteritic ischaemic optic neuropathy (NAION), arteritic ischaemic optic neuropathy (AION), central retinal vein occlusion (CRVO)
- Genetic - Leber’s ON
- Metabolic
- Nutritional - copper, B12, B1, folate deficiency
- Drugs and toxins - methanol, ethambutol, linezolid, amiodarone
What’s non-arteritic ischaemic optic neuropathy (NAION)?
Problem with blood vessel.
Classically small vessel disease risk factors e.g. hypertension, DM
When you stand up, you drop your BP, and you get loss of blood flow to the optic nerve and painless vision loss
What’s arteritic ischaemic optic neuropathy (AION)?
Giant cell arteritis –> loss of blood flow to the optic nerve –> painless vision loss
What’s Leber’s optic neuropathy?
Bilateral sequential (sometimes at the same time) painless vision loss
Progressive
Due to mitochondrial loss
Genetics, positive FHx
Rx: steroids, IVIG
What’s the cause of bilateral optic disc swelling?
- Raised intracranial pressure
- Hypertension
- Bilateral optic neuritis/neuropathy - NMO spectrum disorder
Define papilloedema
Bilateral optic disc swelling secondary to raised intracranial pressure
If no raised intracranial pressure, then its just bilateral disc swelling
How do people get MS?
Genetic susceptibility + environmental trigger
What genes predispose you to MS?
HLA-DRB1*15
What environmental factors can trigger MS?
Smoking
EBV
Further away from the equator (immigrants who migrate before adolescence acquire the risk of the new country)
Sunlight exposure and vitamin D protective
Pathophysiology of MS
- Demyelination (damage to oligodendrocytes) +/- re-myelination
- Axonal loss/atrophy (neurodegeneration)
- White matter and grey matter lesions
- T cell and B cells involved
- Progression starts from the onset of disease
- CNS intrinsic or extrinsic antigen activates T and B cells –> come through BBB –> damage CNS tissue –> further releases antigen into peripheral –> further priming of lymphocytes –> continuous cycle
What are plaques in MS?
Focal demyelination
How long does an MS attack typically last?
It an “itis” - progression over days
Nadir within 2 weeks, resolution within 4 weeks
Lasting greater than 24-48h
May not return to baseline
How does MS present?
What are some common symptoms?
Symptoms depends on location of lesion and functional reserve (if it was in an area that had large functional reserve, may not get symptoms and vice versa)
Common symptoms
- Cognitive impairment
- Fatigue
- Sensation changes - numbness, paraesthesia, pain, MS hug (feeling of tightness around chest or stomach), proprioceptive loss
- Weakness
- Optic neuritis (first clinical event in 20%; occurs in 50% of all MS)
- Cerebellum - ataxia, tremor, dysmetria
- Brainstem - INO (bilateral highly specific), ophthalmoplegia, vertigo, trigeminal neuralgia
- Spinal cord - bladder and bowel dysfunction (urge incontinence, neurogenic bladder, constipation), myelitis
- Lhermitte’s sign (shock like sensation shooting down when you bend your neck)
- Uhthoff’s phenomenon ie pseudorelapse
What is a clinically isolated syndrome?
1st event of MS or once off event
Duration of at least 24h
With or without recovery
60% will develop MS…risk increased by
- > 9 T2 lesions on MRI
- CSF OCBs
- Low vitamin D
What is the Mcdonalds criteria?
- Identify MS in patients who present with a typical clinically isolated syndrome
- Basically shows 2 lesions in time and space
- Uses evidence of clinical attack, MRI and CSF oligoclonal bands
In those who have a clinically isolated syndrome, what are the risk factors for MS?
Young age Large lesion Asymptomatic infratentorial or spinal cord lesion Gadolinium-enhancing lesion Oligoclonal bands in CSF Abnormal visual evoked potentials
How does optic neuritis in MS look on fundoscopy?
60-90% optic neuritis is retrobulbar so you won’t see swollen disc
But eventually will progress to optic atrophy so you will see pale/white disc
List the 4 classic areas you would see MS plaques
1) paraventricular
2) juxtacortical
3) infratentorial
4) spinal cord
How do you see disseminated plaques in time and space on MRI?
Dissemination in space seen when you have T2 lesions in different areas
Dissemination in time seen when you have
- New T2 or gadolinium enhancing lesions on follow up MRI
- Simultaneous enhancing (<1/12 old) and non-enhancing (>1/12 old) lesions
Why are oligoclonal bands important in MS?
Basically you run the CSF and the serum through a western blot and you compare how much IgG is in each.
In MS, you can have increased IgG as you get intrathecal production but this takes a year to develop. Hence if you have high CSF IgG, this indicates a chronic process = dissemination in time
What’s a radiologically isolated syndrome in MS?
Looks like MS on MRI but no clinical symptom
More likely to get progressive symptoms
Currently not treated
Acute treatment of MS relapse
1) 3/7 IV methylpred or PO methylpred
- Accelerates recovery from MS relapse but does not modify disease progression/disability
2) Plasmapharesis for severe attacks