Multiple Sclerosis Flashcards
Multiple sclerosis : Definition
Multiple sclerosis (MS) is a chronic and progressive autoimmune condition involving;
* demyelinationin the central nervous system.
* The immune system attacks the myelin sheathof the myelinated neurones.
Multiple sclerosis : Pathophysiology
1 . Function of Myelin
Myelin covers the axons of neurones and helps electrical impulses travel faster.
Myelin is provided by cells that wrap themselves around the axons:
* Oligodendrocytes in the central nervous system
* Schwann cells in the peripheral nervous system
2 . MS only effects Myelin on the nerves in the CNS
* Targets Oligodendrocytes only
3 . Inflammation and immune cell infiltration damages the Myelin on the CNS nerve cells - ‘Demyelination’
4 . Slows down electrical signals transmitted in the CNS
Multiple sclerosis : Causes
Potential causes are;
* Genetics
* Epstein–Barr virus (EBV)
* Low vitamin D
* Smoking
* Obesity
Multiple sclerosis : Incidence
- 3 times more common in women
- most commonly diagnosed in people aged 20-40 years
- much more common at higher latitudes
Multiple sclerosis : Patterns of disease
1. Relpasing - remitting
* most common
* Acute attack 1-2 months followed by period of remission.
During relapse episodes, disease can further be classified into
* Active: new symptoms are developing, or new lesions are appearing on the MRI
* Not active: no new symptoms or MRI lesions are developing
* Worsening: there is an overall worsening of disability over time
* Not worsening: there is no worsening of disability over time
2. Secondary progressive disease
* Deterioration of symptoms from initial relapsing-remitting disease
Symptoms are expanding and getting worse - with incomplete remission
3 . Primary progressive
* Gradual worsening of symptoms from the point of diagnosis
* No relapse or remission
Multiple sclerosis : Visual Clinical features
1. Optic neuritis :
* demyelination of the optic nerve and presents with unilateral reduced vision
* *Developing over hours to days.
2 . Central scotoma (an enlarged central blind spot)
3. Eye movement abnormalities:
* Diplopia, restricted eye movement
* Demyelination of occulormotor, trochlear or abducens nerve
4 . Relative afferent pupillary defect :
* affected eye constricts more when shining a light in the contralateral eye than when shining it in the affected eye.
Multiple sclerosis : Neurological clinical features
1 . Focal motor weakness
* Incontinence
* Facial nerve plasy
* Limb paralysis
2 . Facial sensory symptoms
* Trigeminal neuralgia
* Numbness, Paresthesia
Dorsal column lesion
* Lhermitte’s sign ;
Cause : Demyelination of nerves in cervical spinal chord in dorsal column
Sx : Flexing neck causes electric shock sensation down the spine
- Sensory ataxia : loss of proprioception, leading to loss of balance and + Rhomberg’s
Cerebellar lesion
* Cerebellar ataxia
Multiple sclerosis : Investigations
- MRI : High T2 lesions, periventricular plaques
- Lumbar punctur : Oligoclonal bands
Multiple sclerosis : Diagnosis
Diagnosis can be made on the basis of;
1. Clinical picture : > 2 relapses
And
2. Clinical investigation : MRI, CSF
Multiple sclerosis : Acute relapse mx
Acute relapse
Mx : High dose Methylprednisolone for 5 days
* Shorten length of acute relapse
Multiple sclerosis : Maintainance therapy
Disease modifying drugs
* Aim : Reduce risk of relapse
Indication :
* relapsing-remitting disease + 2 relapses in past 2 years + able to walk 100m unaided
- secondary progressive disease + 2 relapses in past 2 years + able to walk 10m (aided or unaided)
Multiple sclerosis : Symptoms control
1 . Fatigue :
* Amantadine
2 . Spasticity :
* Baclofen
* Gabapentin
3 . Urge incontinence :
* Solifenacin
4 . Oscillopsia : visual field oscillates
* Gabapentin
