Case 23 questions 17-30

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Enjoy working thorugh the following questions. We hope they aid your learning. If you have any issues or feedback, please email [email protected]

Question 17

Which of these is true regarding opioid mechanism of action?

  1. delta receptor effects are responsible for respiratory depression
  2. μ receptor effects may be proconvulsant
  3. k receptor effects cause constipation
  4. delta and k receptor effects may be dependence
  5. All three receptor effects contribute to analgesia

The correct answer is option e, All three receptor effects contribute to analgesia

It is the μ receptors that are responsible for respiratory depression, it is the d receptors that may cause proconvulsant effects, it is the μ receptors responsible for constipation and it is only μ receptors responsible for dependence. All three receptors however, are responsible for some of the analgesic effect.

Question 18

Which of these statements is false regarding treatments for osteoarthritis

  1. Intra-articular corticosteroid injections are considered as an initial management step
  2. Oral analgesics such as paracetamol are considered 1st line
  3. Topical capsaicin can be considered as an adjunct to core treatments for knee or hand osteoarthritis
  4. Topical NSAIDs are considered before use of oral NSAIDs/COX-2 inhibitors or opioids
  5. Opioids can be added only if there is a poor response to paracetamol or topical NSAIDs

The correct answer is option a, Intra-articular corticosteroid injections are considered as an initial management step

Intra-articular corticosteroid injections are considered as an adjunct to core treatments in moderate to severe pain only.

Question 19

Which isn’t a consequence of peripheral sensitisation?

  1. Threshold of pain is lowered
  2. Responsiveness increased
  3. Increased likelihood of further damage
  4. During inflammation, the skin is more susceptible to pain
  5. It is protective in the short term

The correct answer is option c, Increased likelihood of further damage

Peripheral sensitisation reduces likelihood of further damage, the others are true.

Question 20

Where does central sensitisation occur?

  1. Brain only
  2. Synapses of ascending pathways
  3. Synapses of descending pathways
  4. Nerve axons in spinal cord
  5. Peripheral nerves

The correct answer is option b, Synapses of ascending pathways

Central sensitisation occurs in synapses of ascending pathways

Question 21

Which is true regarding the gated theory of pain?

  1. A-alpha and A-beta fibres stop the pain response
  2. The pain response is inhibited by dorsal column inhibition
  3. The dampening down of the pain response requires transmission via interneurons
  4. 1st order neurones connect interneurons to the anterolateral system
  5. A-delta fibres contribute to dampening down the pain response

The correct answer is option c, The dampening down of the pain response requires transmission via interneurons

A-alpha and A-beta fibres dampen down the pain response-they do not stop it. The pain response is inhibited by dorsal column stimulation, not inhibition. 1st order neurones connect peripheral receptors to interneurons, not interneurons to the anterolateral system. A-delta fibres are pain fibres so don’t contribute to dampening down the pain response. The dampening down of the pain response does require transmission via interneurons.

Question 22

Which type of pain fibres respond to dull, slow pain

  1. A-alpha
  2. A-gamma
  3. A-delta
  4. B fibres
  5. C fibres

The correct answer is option e, C fibres

C fibres respond to dull, slow, ache pain whereas A-delta responds to sharp, fast pain

Question 23

45 Year Old Mary has a 3 month history of stiffness in various joints. It is predominantly affecting her distal interphalangeal joints of her left hand. She also describes her left knee, right ankle and right metatarsophalangeal joints as being painful in the last few weeks.

Upon inspection, Mary has onycholysis and pitting of most nails on her hands.

What is the most likely diagnosis?

  1. Gout
  2. Psoriatic arthritis
  3. Osteoarthritis
  4. Rheumatoid arthritis
  5. Ankylosing spondylitis

The correct answer is option b, Psoriatic arthritis

Psoriatic arthritis is usually an asymmetrical oligoarthritis commonly affecting wrists, hands (DIP rather than MCP), feet and ankles. It is associated with psoriasis of the skin or nails, which usually precedes the onset of arthritis but the opposite can occur.

Question 24

What classification of arthritis is gout?

  1. Mechanical
  2. Crystal-induced arthritis
  3. Inflammatory
  4. Infective
  5. Juvenile

The correct answer is option b, Crystal-induced arthritis

Gout is a negatively bifringent needle shaped crystals.
Mechanical is osteoarthritis.
Inflammatory includes RA and psoriatic arthritis.
Infective is septic arthritis.
Juvenile idiopathic arthritis is a separate condition.

Question 25

In November, 41 Year old James pays a visit to his GP complaining of a red swollen left knee. Upon examination it is red and stiff, and the right knee is similar but “the left knee is giving me more bother doc” he tells his GP. He works as a carpenter and is finding it harder to hold his tools in his right hand as he notices his fingers are beginning to swell too. He tells you he is struggling in the cold mornings and has to keep his hands under a hot water tap for a while. He denies any cuts or grazes to the knees, and informs you he does not drink alcohol but smokes 10 cigarettes daily.

What biochemical marker would be most specific to confirm the most likely diagnosis?

  1. Beta-HCG
  2. Rheumatoid factor
  3. Troponin
  4. Anti-CCP
  5. BNP

The correct answer is option d, Anti-CCP

Rheumatoid factor is positive in 60-70% of patients with RA however it is also positive in other diseases and in 5-10% of normal population.

Therefore, positive result does not definitely mean RA present, and a negative result does not mean RA not present. Anti-CCP is present in around 70-80% patients with RA, therefore, it is more specific to RA than rheumatoid factor.

Question 26

What is the most likely cause of loss of central tolerance leading to autoimmune disease?

  1. HLA Haplotype
  2. Decline in regulatory T cell function
  3. Side effects of medication
  4. Varicella Zoster Virus infection
  5. Post-translational modification

The correct answer is option a, HLA haplotype

All the rest are more likely to cause loss of peripheral tolerance.

Question 27

What HLA allele is linked to SLE and myasthenia gravis?

  1. HLA-DR4
  2. HLA-B27
  3. HLA-DQ8
  4. HLA-DR3
  5. HLA-DRB1

The correct answer is option d, HLA-DR3

HLA-DR3 – Myasthenia gravis, along with Hashimoto’s thyroiditis and primary sclerosing cholangitis
HLA-DR4 – Rheumatoid arthritis
HLA-B27 – Ankylosing spondylitis
HLA-DQ8 – coeliac disease
HLA-DRB1 – several autoimmune conditions have been linked including type 1 diabetes

Question 28

60 Year Old Sarah was diagnosed with Rheumatoid arthritis in her forties. However, recently she has noticed her eyes have became dry, and swollen; at time they are painful and she avoids driving to be cautious. In addition, she complains of a dry mouth and taking plenty of sips of water.

She has also been feeling under the weather recently, with fatigue, loss of appetite.

What is the most likely diagnosis?

  1. Primary Sjogren’s Syndrome
  2. Secondary Sjogren’s Sydrome
  3. Hypothyroidism
  4. Diabetes Type 2
  5. Hyperthyroidism

The correct answer is option b, Secondary Sjogren’s Sydrome

Sjogren’s syndrome is an autoimmune disease than damages moisture-producing glands. While it can occur on its own it can also be triggered by other autoimmune diseases, including RA. In this case it is defined as secondary Sjogren’s. Common symptoms include; fatigue, brain fog, fever, loss of appetite, and joint pain

Question 29

Which enzyme does methotrexate inhibit, which is essential for the synthesis of purines and pyrimidines?

  1. Dihydrofolate reductase
  2. Thymidylate synthetase
  3. Dihydroorotate dehydrogenase – MOA of leflunomide
  4. 5-aminoimidazole-4-carboxamide ribonucleotide
  5. Phosphodiesterase

The correct answer is option a, Dihydrofolate reductase

Methotrexate is actively transported into cells and competitively inhibits dihydrofolate reductase (DHFR), an enzyme that participates in the tetrahydrofolate synthesis. DHFR catalyses the conversion of dihydrofolate to the active tetrahydrofolate. Folic acid is needed for the de novo synthesis of the nucleoside thymidine, required for DNA synthesis.

Also, folate is essential for purine and pyrimidine base biosynthesis. Methotrexate, therefore, inhibits the synthesis of DNA, RNA, thymidylates, and proteins.

Question 30

Select the following feature which reduces risk of developing osteoarthritis

  1. Female
  2. Obesity
  3. Age
  4. Male
  5. Family history of osteoarthritis

The correct answer is option d, being male

The other factors increase risk of developing osteoarthritis

Credits

  • 17-20 (Oliver Mann, 3rd year),
  • 21-30 (Amy Hookings, 3rd year)