Multiple Sclerosis

Question 1

What is multiple sclerosis?

Answer 1

Chronic, degenerative disease of the CNS caused by immune-mediated inflammatory processes → results in demyelination and axonal degeneration in the brain and spinal cord.

Question 2

What are the different types of MS a patient could have?

Answer 2

1. Relapsing-Remitting Disease (85%) ⇒ acute attacks (last 1-2 months) followed by periods of remission
2. Secondary Progressive Disease ⇒ relapsing-remitting patients who have deteriorated and have developed neurological signs and symptoms between relapses
3. Primary Progressive Disease ⇒ progressive deterioration from onset

Dissemination in Time and Space→ lesions in the CNS must have occured in at least 2 different places and at least 2 different times

Question 3

What is the cause of MS?

Answer 3

UNKNOWN
- Autoimmune basis with potential environmental trigger in genetically susceptible individuals
- Immune-mediated damage to myelin sheaths results in impaired axonal conduction

Question 4

What are the risk factors for MS?

Answer 4

Genetic predisposition & environmental risk factors (low vitamin D levels, smoking, EBV, much more common in Caucasian populationa)

Question 5

What are the presenting symptoms of MS?

Answer 5

1. Significant Fatigue & Headache
2. Optic Neuritis (earliest manifestation - inflammation of optic nerve) → unilateral, impaired vision and colour blindness. May also have pain in moving eye. RAPD.
   - RAPD ⇒ assessed via swinging flashlight test. Both pupils appear dilated when affected eye is illuminated.
3. Sensory Disturbance (patchy paraesthesia)
4. Weakness after walking
5. Spasticity, Hyperreflexia and positive Babinski Sign → UMN signs
6. Intranuclear Opthalmoplegia (INO)
   - Lesion of the medial longitudinal fasciculus, blocking the connection between the contralateral sixth nerve nucleus and the ipsilateral third nerve nucleus, thus affecting horizontal gaze.
   - Causes ipsilateral impaired adduction (move temporally) in the eye and nystagmus in the other abducting (move nasally) eye.
   - Right INO = right eye unable to adduct (nystagmus will occur in left eye simultaneously - ie. when left eye is abducting)
7. Leg cramping
8. Bladder disorders (Urinary Incontinence) → may need to self-catheterise

Question 6

What signs of multiple sclerosis can be found on physical examination?

Answer 6

1. Optic Neuritis
   - Impaired visual acuity (MOST COMMON)
   - Loss of coloured vision
2. Visual Field Testing
   - Central scotoma (if optic nerve is affected)
   *Scotoma = a blind spot in the normal visual field
   - Field defects (if optic radiations are affected)
3. Relative Afferent Pupillary Defect (RAPD)
4. Internuclear Ophthalmoplegia
   - Lateral horizontal gaze causes failure of adduction of the contralateral eye
   - Indicates lesion of the contralateral medial longitudinal fasciculus
5. Sensory
   - Paraesthesia
6. Motor
   - UMN signs
7. Cerebellar
   - Limb ataxia (intention tremor, past-pointing, dysmetria)
   - Dysdiadochokinesia
   - Ataxic wide-based gait
   - Scanning speech
8. Uhthoff’s Sign - worsening of neurological symptoms as the body gets overheated from hot weather, exercise, saunas, hot tubs etc.
9. Lhermitte’s Sign - an electrical sensation that runs down the back and into the limbs when the neck is flexed

Question 7

What investigations are used to diagnose/ monitor MS?

Answer 7

1. Clinical:
   - absence of alternative diagnosis
   - Dissemination in time
   - Dissemination in space
   (This means the pt will have 2 different spaces in the brain affected, shown by >1 symptom, that appears in 2 different scenarios, e.g. experincing weakness today and eye pain a year later)
2. McDONALD criteria:
   Diagnosis is based on the finding of two or more CNS lesions with corresponding symptoms, separated in time and space
3. Lumbar Puncture
   - Microscopy - exclude infection/inflammatory causes
   - CSF electrophoresis shows unmatched oligoclonal bands
4. MRI Brain (contrast needed to view lesion) used to look for evidence of central demyelination to support dissemination in space, while gadolinium enhancement of some lesions and not others would demonstrate dissemination in time – both being required to achieve a diagnosis of multiple sclerosis.
   - Plaques can be identified
   - Gadolinium enhancement shows active lesions
5. Evoked Potentials
   - Visual, auditory and somatosensory evoked potentials may show delayed conduction velocity

Question 8

How is MS managed?

Answer 8

1. Acute Exacerbations → IV Glucocorticoids (methylprednisolone) as first line. Plasma Exchange as second line.
2. Relapsing MS → Immunomodulators (beta-interferon)
3. Spasticity → baclofen and gabapentin

Question 9

Describe the epidemiology of MS?

Answer 9

F>M (3:1), peak incidence 20-40 yrs old, increased prevalence in white population

Most common = young white female