Wired for Pain
These thinly myelinated fibres carry "first pain": sharp, well-localised and fast.
A) A-alpha fibres
B) A-beta fibres
C) A-delta fibres
D) C fibres
C) A-delta fibres
A-delta fibres carry fast, pricking first pain; unmyelinated C fibres carry slow, burning, poorly localised second pain.
The active metabolite of morphine, which accumulates in renal failure and causes prolonged sedation and respiratory depression
A) Morphine-3-glucuronide
B) Morphine-6-glucuronide
C) Hydromorphone
D) Normorphone
B) Morphine-6-glucuronide
M6G is a potent mu agonist cleared by the kidney
A) Lidocaine
B) Procaine
C) Cocaine
D) Bupivacaine
C) Cocaine
Cocaine was introduced into clinical practice by Carl Koller in 1884 for eye surgery, marking the birth of modern local anesthesia.
Brief, unilateral, electric-shock facial pain triggered by brushing teeth or a light breeze:
A) Trigeminal neuralgia
B) Cluster headache
C) Persistent idiopathic facial pain
D) Temporomandibular joint dysfunction
A) Trigeminal neuralgia
Classic trigeminal neuralgia is often due to vascular compression of the nerve root; microvascular decompression is an option when drugs fail.
The concentration of lipid emulsion used to treat local anaesthetic systemic toxicity.
A) 5%
B) 10%
C) 50%
D) 20%
D) 20%
The ASRA dose is a 1.5 mL/kg bolus of 20% lipid emulsion, followed by an infusion.
This neuropeptide, released from central C-fibre terminals, acts on NK-1 receptors in the dorsal horn:
A) Substance P
B) Met-enkephalin
C) GABA
D) Glycine
A) Substance P
Substance P and CGRP are co-released with glutamate and amplify nociceptive transmission.
Patients do not develop meaningful tolerance to this opioid side effect:
A) Nausea
B) Sedation
C) Constipation
D) Respiratory depression
C) Constipation
Constipation and miosis persist, so laxatives should be prescribed with regular opioids.
Which theory, proposed by Melzack and Wall in 1965, fundamentally changed modern understanding of pain modulation?
A) Specificity theory
B) Pattern theory
C) Gate Control theory
D) Neuromatrix theory
Which feature in a patient with low back pain is a red flag needing urgent imaging?
A) Pain worse after prolonged sitting
B) Saddle anaesthesia
C) Paraspinal muscle tenderness
D) Pain eased by lying down
B) Saddle anaesthesia
This suggest cauda equina syndrome, a surgical emergency needing urgent MRI.
Performed at C6 over Chassaignac's tubercle for sympathetically maintained upper limb pain; a Horner syndrome confirms success.
A) Coeliac plexus block
B) Stellate ganglion block
C) Lumbar sympathetic block
D) Superior hypogastric plexus block
B) Stellate ganglion block
Ptosis, miosis and anhidrosis show head and neck sympathetic block; a rise in upper limb skin temperature confirms limb sympathectomy.
At the presynaptic terminal of primary afferents, opioids reduce neurotransmitter release mainly by this action.
A) Blocking voltage-gated sodium channels
B) Opening ligand-gated chloride channels
C) Activating adenylyl cyclase
D) Inhibiting voltage-gated calcium channels
D) Inhibiting voltage-gated calcium channels
Absorption from a transdermal fentanyl patch increases sharply with this, risking toxicity.
A) Cooling the skin
B) Clipping hair at the site
C) Applying it to the upper arm
D) Fever or a heating pad over the patch
D) Fever or a heating pad over the patch
Heat increases skin blood flow and drug release; patches are unsuitable for acute pain or rapid titration.
Credited with the first spinal anaesthetic in 1898, he described intravenous regional anaesthesia in 1908:
A) August Bier
B) Fidel Pages
C) Gaston Labat
D) John Bonica
A) August Bier
Bier performed the first planned, successful operation under true subarachnoid (spinal) anesthesia at the University of Kiel, using an intrathecal injection of cocaine.
Chronic widespread pain with fatigue, unrefreshing sleep and cognitive symptoms, without inflammation or structural damage.
A) Polymyalgia rheumatica
B) Rheumatoid arthritis
C) Polymyositis
D) Fibromyalgia
D) Fibromyalgia
Fibromyalgia is a central sensitization syndrome; exercise, education and drugs such as duloxetine or amitriptyline are the mainstays.
Under ASRA guidelines, after a prophylactic dose of low-molecular-weight heparin (e.g. enoxaparin 40 mg once daily), wait at least this long before neuraxial puncture.
A) 4 hours
B) 12 hours
C) 24 hours
D) 48 hours
B) 12 hours
A patient with complete brachial plexus avulsion has severe burning pain in an insensate arm. Which mechanism best explains it?
A) Deafferentation, with abnormal firing of central neurons that have lost their input
B) Peripheral sensitization of intact nociceptors in the arm
C) Ongoing inflammation of the plexus
D) Activation of muscle nociceptors by spasm
A) Deafferentation, with abnormal firing of central neurons that have lost their input
Avulsion pain is a central neuropathic pain; the DREZ (dorsal root entry zone) lesion is a surgical option for refractory cases.
When switching to a different opioid, the calculated equianalgesic dose is reduced by 25–50% mainly because of this.
A) Different elimination half-lives
B) Active metabolites
C) Differences in protein binding
D) Incomplete cross-tolerance
D) Incomplete cross-tolerance
Tolerance to one opioid does not fully transfer to another, so full equianalgesic doses can cause overdose.
The International Association for the Study of Pain (IASP) was founded in this year.
A) 1946
B) 1965
C) 1973
D) 1990
C) 1973
It grew out of a 1973 meeting organised by Bonica in Issaquah, Washington.
Buttock pain with sciatic-type radiation, reproduced by flexion, adduction and internal rotation of the hip
A) Trochanteric bursitis
B) Facet arthropathy
C) Piriformis syndrome
D) Sacroiliac joint dysfunction
C) Piriformis syndrome
The sciatic nerve is irritated as it passes beneath or through the piriformis muscle.
One of the following gives shoulder surgery analgesia while largely sparing the phrenic nerve.
A) Superficial cervical plexus block
B) Supraclavicular block
C) Stellate ganglion block
D) Suprascapular plus axillary nerve blocks
D) Suprascapular plus axillary nerve blocks
The suprascapular nerve supplies most of the shoulder joint; the axillary nerve covers the anterior and lateral capsule.
Loss-of-function mutations in this sodium channel cause congenital insensitivity to pain
A) Nav1.5
B) Nav1.4
C) Nav1.7
D) Nav1.1
C) Nav1.7
Nav1.7 is concentrated in nociceptors and is a major target for new analgesic development.
Suzetrigine, approved by the US FDA in January 2025 for moderate-to-severe acute pain, is the first in a new non-opioid class. It selectively blocks this channel.
A) Nav1.7
B) TRPV1
C) Nav1.8
D) Nav1.5
C) Nav1.8
Nav1.8 is expressed almost only in peripheral nociceptors, so blocking it avoids CNS effects and addiction potential.
Founder of St Christopher's Hospice in 1967, she introduced the concept of "total pain": physical, psychological, social and spiritual.
A) Florence Nightingale
B) Cicely Saunders
C) Elisabeth Kübler-Ross
D) Virginia Apgar
B) Cicely Saunders
Saunders trained as a nurse, social worker and doctor, and championed regular rather than as-needed dosing of opioids for cancer pain.
Six weeks after a distal radius fracture, a woman has a burning, swollen, sweaty hand with colour change and allodynia, and no nerve lesion. What should management focus on first?
A) Further immobilisation in a cast
B) Long-term strong opioids alone
C) Early physiotherapy and functional restoration, with analgesia
D) Surgical sympathectomy
C) Early physiotherapy and functional restoration, with analgesia
This is CRPS type I; rehabilitation (including graded motor imagery and mirror therapy) is the cornerstone, with drugs and sympathetic blocks to enable it.
The PENG block targets the articular branches of these nerves supplying the anterior hip capsule.
A) Femoral, obturator and accessory obturator nerves
B) Femoral, lateral femoral cutaneous and genitofemoral nerves
C) Sciatic and obturator nerves
D) Saphenous and femoral nerves
A) Femoral, obturator and accessory obturator nerves
The pericapsular nerve group block deposits local anaesthetic between the iliopsoas tendon and the pubic ramus, largely sparing the quadriceps.