MS - pathology

Question 1

Who does MS most commonly present in?

Answer 1

• young and middles aged adults
• 3x more common in women
• Caucasian northern Europeans > links to vitamin D deficiency > increased risk

Question 2

What is the nature of MS?

Answer 2

• unpredictable course of illness > symptoms change frequently
• full recovery > permanent disability

Question 3

What is the cause of MS?

Answer 3

• autoimmune disease
• principle member of “demyelinating diseases”
• possible genetic, lifestyle, environmental, infectious factors
• distance from the equator i.e. N Europe > even if immigration to high risk areas as a child
• exposure to less sunlight > Vit D deficiency > increased risk

Question 4

Pathology of MS?

Answer 4

• MS is an immune-mediated destruction of myelin
• plaques in brain and SC, predominantly in white matter (axons of neurons are in WM > myelin sheaths and Schwann cells)
• random lesions (damage) around cerebral hemispheres, brainstem, cerebellum and SC > mainly periventricular WM > anterior and posterior horns of ventricles (central cavities in brain)
• immune response triggered by unknown mechanism

Question 5

What is the process of the unknown immune response?

Answer 5

• T CELLS in PERIPHERAL immune system activated (CD4 and CD8)
• t cells are MYELIN SPECIFIC and autoreactive
• crosses complex BLOOD BRAIN BARRIER
• t cells reactivated by local CNS antigens (macrophages, microglia or B cells)
• they secrete pro-inflammatory CYTOKINS
• PLASMA cells secrete ANTIBODIES against myelin
• cytokines and antibodies destroy myelin sheath
• leads to further inflammation > microglia triggered to secrete autoLYTIC chemicals
• leads to further tissue damage and AXONAL loss

Question 6

What are the tests used to diagnose MS?

Answer 6

LUMBAR PUNCTURE - presence of proteins, oligoclonal bands and lymphocytes in cerebrospinal fluid (CSF)
ELECTROPHORESES - immunoglobulins in CSF (igG)
EVOKED POTENTIALS (controlled initiated peripheral nerve stimulation) - visual, auditory and somatosensory brain electrical activity
MRI - inflammation or plaques (especially around anterior and posterior horns of ventricles)

Question 7

What is MS pathophysiology?

Answer 7

• MS > multiple scarring
• rate of conduction of nerves is slowed down > no nodes of Ranvier for saltatory propagation between myelin sheaths of neurons > have to travel whole length of neuron
• chronic inflammation can result in axonal damage > decreased signals > fatigue
• symptoms are dependent upon which areas of CNS are affected

Question 8

What are the common types of MS?

Answer 8

~ relapsing-remitting > periods of symptoms then return to set point, short duration episodes with remaining symptom free for months to years
~ secondary-progressive > slow, steady progression with/without relapses, relapses don’t fully remit
~ primary-progressive > steady worsening from the start, no periodic relapses and remissions
~ progressive-relapsing > steadily worsen from onset, flare ups (with/out remissions)

Question 9

Signs and symptoms of MS

Answer 9

• fatigue
• visual problems (blurred, diplopia)
• cognitive and perceptual problems
• exacerbated symptoms by heat and cold
• alteration in muscle tone (low, high/spasticity)
• gait and mobility disturbances
• pain (neuropathic or msk)

Question 10

Treatment options for MS

Answer 10

*no cure ~ symptom management
- pharmacology > steriods for relapses (methylprednisolone oral or IV) > disease modifying therapy (DMT) to change immune response
- physiotherapy

Question 11

Physio treatment options for MS

Answer 11

• posture and balance re-education > gym ball
• gait re-education > prepare foot for standing > facilitated full gait cycle
• mobilisation and tactile simulation > hand prior to reach and grasp
• dependent of areas of CNS affected by demyelinated nerves