Multiple Sclerosis and Demyelinating Disorders Flashcards
Multiple sclerosis
Pathogenesis and Immunology
Pathogenesis
* ****Inflammation, demyelination and axon degeneration in multiple sites of CNS - brain, spinal cord, optic nerve
* Most widely accepted theory -> inflammatory autoimmune disorder mediated by autoreactive lymphocytes - later dominated by microglial activation and chronic neurodegeneration
* Other theories -> immune due to chronic viral infection, nonimmune non-inflammatory etiology due to genetically determined neuroglial degenerative process
Epidemiology
* ****F: M = 3:1
* Usually ages 15-50. 5% MS population < 18 years
* Genetics - HLA DRB1
* Risk factors -> lack of sun exposure, low vitamin D levels, EBV and other viruses, temperate latitude, smoking (increased relapse rates in smokers), obesity, early adulthood, female sex
* 2-4% risk if first degree relative affected
* Concordance in monozygotic twins 30-50%
Clinical features multiple sclerosis
Commonest = sensory symptoms in limbs (31%), then visual loss (14%)
* * Internuclear ophthalmoplegia
* Optic neuritis - 50% chance of developing MS by 15 years
○ Fundoscopy - reduction in visual acuity, pappilitis, optic atrophy, scotomata (usually central)
* RAPD
* Upper motor neurone weakness
* Cerebellar signs
* Posterior column sensory loss
* Faecal/urinary incontinence
* Lhermitte’s sign
○ Electric shock like sensation in the limbs or trunk following neck flexion
○ Also seen in subacute combined degeneration of the cord, cervical spondylosis, cervical cord tumours, foramen magnum tumours, nitrous oxide abuse, mantle irradiation
* Uhthoff’s phenomenon
○ Worsening symptoms in the setting of hotter temperatures or exercise
§ Common in MS - also occurs in peripheral disorders like myasthenia gravis
Notes on clinically isolated syndrome in multiple sclerosis
- First clinical episode suggestive of MS - thought of as a precursor in MS
- Monophasic clinical episode, acute or subacute onset lasting > 24 hours
- Resembles typical MS relapse, with symptoms and objective findings reflecting focal or multifocal inflammatory demyelinating event in CNS
- No evidence of previous episodes of demyelination from patient history
- Develop over hours - days, remit over weeks to months
- Typical syndromes include (also typical for relapse) -> unilateral optic neuritis, painless diplopia, brainstem/cerebellar syndrome, partial transverse myelitis - often predominantly sensory, Lhermitte symptom, sphincter/erectile dysfunction
**Risk of progression to MS
**if abnormal MRI - 70-90% develop MS
Normal MRI - 10% will develop MS
Gadolinium enhancing lesions - higher risk of progression
MRI better predictor of development of MS than CSF or evoked potentials
Notes on multiple sclerosis and optic neuritis
- First presenting symptom of MS in 21% cases
- Probability of developing MS by 15 years after onset of optic neuritis 50%
- Strongly related to presence of lesions on a baseline MRI
- No lesions - 25% probability during follow up period, risk very low after ten years
- 1 or more lesions - 72% probability, risk substantial even after ten years
- Increased risk of progression to MS: females, younger adults > adults or children, abnormal brain MRI, recurrence, retinal perivenous sheathing, CSF oligoclonal bands, severe papillitis
- Note simultaneous bilateral ON - lower MS risk
**Symptoms
**Monocular, central visual loss, pain (particularly on eye movement), altered colour vision e.g. red -> dark/bleached, red-green more affected in late phase , phosphenes, uhthoff phenomenon, reduced contrast sensitivity
Recovery: 90% vision 6/12 or better at one year
Poorer prognosis: moer severe visual loss at presentation, longer lesion in optic nerve, african-american heritage, children
Recurrence: 35% at 10 years
Notes on eye movement abnormalities in MS
**Gaze abnormalities
**Internuclear ophthalmoplegia
One-and-a-half syndrome
Dorsal midbrain syndrome
Skew deviation
**Nystagmus
**Horizontal, vertical, pendular
**Slowed smooth pursuit movements
Ocular motor nerve palsies (uncommon)
**One and a half syndrome
**Horizontal gaze palsy on looking to one side plus impaired adduction on looking to the opposite side
Other features - turning out (exotropia) of the eye opposite the lesion
If ilsiplateral LMN facial nerve weakness = 8 and a half syndrome
Dorsal pons lesion - stroke, MS
Notes on bladder/bowel/sexual dysfunction in MS
Notes on paroxysmal symptoms in MS
Notes on radiologically isolated syndrome in multiple sclerosis
- Incidental white matter lesions
- Clinical MS develops in up to 50% of people with RIS, sometimes with a primary progressive course
Notes on MRI in multiple sclerosis
- FLAIR very sensitive
- MRI shows more active MS lesions than those that produce clinical disease
- Difficulties in patients > 50 as ischaemic changes can mimic MS lesions
- **Dissemination in space - **see attached slide
- **Dissemination in time: **simultaneous contrast enhancging and non-enhancing lesions, or new lesions on follow-up MRI. Sensitivity 72-85%, specificity 67-92%
- **Spinal lesions - **short segement transverse myelitis. If LETM - think NMO. Cord lesions in MS most common in cervical spine.
- **Optic neuritis - **Fat-suppressed MRI or orbits: enhancement of the right optic nerve
- Dawson’s fingers = lesions radiating out from corpus callosum
**Gadolinium
**Enhancement indicates “active” lesions and usually persists for < 1month, may last > 8 weeks
Decreases after steroid treatment
The more gad you use the more lesions you see
**Hypointense T1 lesions
**Black holes - suggest axonal loss
Especially common in SPMS
Correlate better than active lesions with disability and cognitive impairment and progression of disease
Notes on blood and CSF testing in multiple sclerosis
Notes on visual evoked potentionals testing in multile sclerosis
McDonald Criteria for diagnosis of MS
Notes on relapsing-remitting MS
-Clearly defined attacks, due to recurrent demyelination within the CNS
-Either full or incomplete recovery
-Minimal disease progression between relapses, though severe disability may result from a relapse
-Diagnosis depends on demonstration of dissemination in time and in space
-Differentiate pseudorelapses from true relapses
Notes on progressive MS
**SPMS: initial relapsing-remitting course followed by gradual worsening
**May have occasional relapses, minor remission and plateaus
Transition from RRMS to SPMS occurs at a median of 12 years from diagnosis and 19 years from first symptom
Disease modifying treatment available for active sPMS with relapses
**PPMS: progressive accumulation of disability from disease onset
**Often progressive spastic parapareiss or ataxia, rarely cognitive, visual or brainstem
May have relapses, temporary minor improvement and occasional plataeus
Males= females. Mean age of onset = 40 years
Multiple sclerosis
Treatment of acute relapses
- 3-7 day course IV methyprednisolone (500-100mg daily) +/- short prednisone taper
- 3-7 days course prednisone (625-1250mg daily) +/- short taper
○ Lots of tablets
○ Small RCTs - no difference in benefits oral vs IV
§ Exception optic neuritis - oral steroids increased risk of recurrent ON - Plasma exchange considered for acute, severe neurological deficits cause by MS attacks showing poor response to high dose glucocorticoids
○ Patients with gadolinium-enhancing lesions on MRI before treatment had best response to PLEX
- 3-7 days course prednisone (625-1250mg daily) +/- short taper