Pathology of CNS

Question 1

motor neurone disease pathophysiology

Answer 1

Amyloid lateral sclerosis
- progressive degeneration and weakness due to loss of muscle innervation
-problems in moving limbs, swallowing , breathing
- sporadic unknown causes
- 3 years life span
In motor neurone disease, damage to the ventral horns of the spinal cord leads to atrophy of the ventral roots. Neurons in the frontal and temporal lobes also degenerate

Both upper and lower Motor neurones are involved .

Question 2

Lambert-eaton Syndrome Pathology

Answer 2

Associate with small cell lung cancer
due to :
a) paraneoplastic (immune system has autoantibodies to ca2+ channels )
b) non paraneoplastic (thyroid graves disease, type1 diabetes )
autoantibodies for ca2+ channels on pre synaptic neurone .

Symptoms:

• proximal muscle weakness
• absent reflexes
• ptosis
• dry mouth , erectile dysfunction , sluggish pupils

Treatments includes:

• malignancy
• Amifampridine
• guanidine
• pyrostigmine ( acetylcholinesterase inhibitor )

Question 3

Polymyositis

Answer 3

develops due to abnormal activation of cytotoxic T lymphocytes (CD8 cells) and macrophages against muscular antigens
Results in :
- rhabdomyolysis (break down of the muscle)
- proximal myopathy.

Question 4

Duchenne Muscular Dystrophy

Answer 4

severe, progressive, muscle-wasting disease that leads to difficulties with movement and, eventually, to the need for assisted ventilation and premature death.

• > X linked recessive so only occurs in males
• > The disease is caused by mutations in DMD (encoding dystrophin) that abolish the production of dystrophin in muscle.
• > but the age of 10 they cant walk
• > degenerated muscle is replaced by fat.

Question 5

what are the antibodies the body produces in myasthenia gravis?(mg)

Answer 5

1) Ach receptor antibodies
2) musK
3)LRP4
2+3 => are involved in creating the Ach Receptor

Question 6

symptoms of MG and how would you diagnose them ?

Answer 6

Symptoms :

• muscle weakness worse at the end of the day (proximal muscles and the small muscles of the head and neck )
• extra ocular muscle weakness ( leads to double vision and diplopia)
• Eyelid muscles ( drooping and ptosis )

Examination consists of :

• repeatedly blinking , do they get ptosis ?
• Upward gaze ( prolonged ) = does this cause double vision or diplopia ?

Diagnoses :

• ACH Antibodies , MusK antibodies, LRP4 Antibodies
• CT of thymus to check for thymoma

Question 7

What is the edrophonian test and when is it used ?

Answer 7

Used in MG

• Given IV
• blocks the cholinesterase enzymes , so increase ACH in NMJ
• should temporarily improve weakness , hence show diagnoses of Myasthenia gravis

Question 8

Treatment of mg

Answer 8

• Acetylcholine inhibitors
• Immunosuppression ( to reduce the antibodies )
• Thymectomy