Multiple sclerosis Flashcards
Define
• Inflammatory demyelinating disease of the CNS clinically defined by 2 episodes of neurological dysfunction (brain, spinal cord, or optic nerves) that are separated in space and time.
What are the different types?
o Relapsing-Remitting MS (85%-90%)
• COMMONEST form
• Clinical attacks of demyelination with complete recovery in between attacks
o Clinically Isolated Syndrome
• Single clinical attack of demyelination
• The attack in itself does NOT count as MS
• 10-50% progress to develop MS
o Primary Progressive MS (10-15%)
• Steady accumulation of disability with NO relapsing-remitting pattern
o Secondary progressive MS
• Late stage of MS, gradually worsening disability
• 75% of RRMS will move to this
o Relapsing-progressive MS (<5%)
• Similar to PPMS but with occasional supra-added relapses on a background of progressive disability from the outset
o Marburg Variant
• Severe fulminant variant of MS leading to advanced disability or death within weeks
Explain the aetiology/ risk factors
• UNKNOWN
• Autoimmune basis with potential environmental trigger in genetically susceptible individuals
• Immune-mediated damage to myelin sheaths results in impaired axonal conduction
• Inflammation, demyelination and axonal loss are the major feature of the MS plaque and cause the clinical manifestations. Plaques are perivenular and have a predilection for distinct CNS sites: optic nerves, periventricular white matter, brainstem and its cerebellar connections and the cervical spinal cord (corticospinal tracts and posterior columns). The peripheral nerves are never affected.
• Risk Factors
o EBV exposure
o Prenatal vitamin D levels
Epidemiology
- UK prevalence: 1/1000
- 2 x as common in FEMALES
- Increasing risk with increasing distance from the equator
- Age of presentation: 20-40 yrs
- Classically presents in white women aged between 20-40 with temporary visual/ sensory loss
What are the presenting symptoms?
• Varies depending on the site of inflammation • Optic Neuritis (COMMONEST) o Unilateral deterioration of visual acuity and colour perception (particularly reds) o Pain on eye movement o Common first symptoms of multiple sclerosis • Sensory o Pins and needles o Numbness o Burning • Motor o Limb weakness o Foot dragging o Spasms o Stiffness o Heaviness • Autonomic o Urinary urgency o Hesitancy o Incontinence o Impotence • Psychological o Depression o Psychosis • Uhthoff's Sign - worsening of neurological symptoms as the body gets overheated from hot weather, exercise, saunas, hot tubs etc. • Lhermitte's Sign - an electrical sensation that runs down the back and into the limbs when the neck is flexed
What are the signs?
• Optic Neuritis
o Impaired visual acuity (MOST COMMON)
o Loss of coloured vision
• Visual Field Testing
o Central scotoma (if optic nerve is affected)
• Scotoma = a blind spot in the normal visual field
o Field defects (if optic radiations are affected)
• Relative Afferent Pupillary Defect (RAPD)
• Internuclear Ophthalmoplegia (uncommon)
o Lateral horizontal gaze causes failure of adduction of the contralateral eye
o Indicates lesion of the contralateral medial longitudinal fasciculus
• Sensory
o Paraesthesia
• Motor
o UMN signs
• Cerebellar
o Limb ataxia (intention tremor, past-pointing, dysmetria)
o Dysdiadochokinesia
o Ataxic wide-based gait
o Scanning speech
What are the appropriate investigations?
• Lumbar Puncture
o Microscopy - exclude infection/inflammatory causes
o CSF electrophoresis shows unmatched oligoclonal IgG bands
• MRI Brain, Cervical and Thoracic Spine (with gadolinium)
o Plaques can be identified
o Hyperintensities in the periventricular white matter
o Gadolinium enhancement shows active lesions
o Demyelinating lesions in the spinal cord
• Evoked Potentials
o Visual, auditory and somatosensory evoked potentials may show delayed conduction velocity
FBC, TSH, vit B12 tested to exclude other causes.
