Pain Central Mechanisms [Med NotesMCQQ&A]

The central mechanism of pain is the way in which the brain processes and interprets pain signals that are transmitted from the body. When tissue in the body is damaged or injured, it sends signals to the brain through nerve fibers called nociceptors. These signals are transmitted to the spinal cord and then to the brain, where they are interpreted as pain.

CENTRAL MECHANISMS OF PAIN [MEDNOTES+MINDMAP]

  • Spinal cord and referred pain
    • Axons of primary afferent nociceptors
    • Termination in dorsal horn of spinal gray matter
    • Release of neurotransmitters (glutamate, substance P, CGRP)
    • Convergence of sensory inputs on single spinal pain-transmission neuron
    • Referred pain
  • Ascending pathways for pain
    • Contralateral spinothalamic tract
    • Thalamic projections to somatosensory cortex and emotional regions of cerebral cortex (cingulate, insular cortex)
    • Frontal cortex and control of behavior
  • Descending pathways for pain control
    • Modulation of pain by descending pathways
    • Role of opioid peptides and nonopioid neurotransmitters
  • Pain perception and the cerebral cortex
    • Role of the somatosensory cortex in discrimination of pain
    • Role of emotional regions of the cerebral cortex in affective dimension of pain
    • Role of the prefrontal cortex in control of pain
  • Plasticity in pain pathways
    • Adaptive changes in response to repeated noxious stimuli
    • Role of glial cells in central sensitization
    • Role of stress in modifying pain perception
  • Developmental and age-related changes in pain pathways
    • Maturation of pain pathways in infants and children
    • Changes in pain pathways with aging
  • Clinical aspects of pain
    • Acute and chronic pain
    • Assessment of pain
    • Management of pain
    • Opioid abuse and addiction

CENTRAL MECHANISMS OF PAIN [CLINICAL SCENARIO MCQ] 

Scenario 1:

A patient is experiencing shoulder discomfort and has recently been diagnosed with inflammation near their central diaphragm. What is the most likely cause of their shoulder discomfort?

A: The patient is experiencing referred pain due to the inflammation near the central diaphragm.

B: The patient has a shoulder injury that is causing the discomfort.

C: The patient is experiencing pain in their shoulder due to inflammation in the brain.

D: The patient has a nerve disorder causing the shoulder discomfort.

Answer: A is correct.

Explanation : The patient is experiencing referred pain due to the convergence of sensory inputs from the shoulder skin and the central diaphragm on pain-transmission neurons in the third and fourth cervical spinal segments. This convergence and activation of spinal neurons by input from deep structures often leads to the mislocalization of pain sensation to a bodily location corresponding to the region of skin innervated by the same spinal segment.

Scenario 2:

A patient has recently undergone a surgical procedure and is experiencing pain. How is their pain likely being transmitted to their brain?

A: The pain is transmitted to the brain through the spinothalamic pathway.

B: The pain is transmitted to the brain through the auditory pathway.

C: The pain is transmitted to the brain through the visual pathway.

D: The pain is transmitted to the brain through the somatosensory pathway.

Answer: A is correct.

Explanation : The spinothalamic pathway, which consists of axons of spinal neurons that send their axons to the contralateral thalamus, is crucial for pain sensation in humans. Interruption of this pathway can result in permanent deficits in pain and temperature discrimination.

Scenario 3:

A patient has a headache and has recently been diagnosed with inflammation in their shoulder. What could be causing the headache?

A: The headache is caused by the inflammation in the shoulder.

B: The headache is caused by a brain tumor.

C: The headache is caused by eyestrain.

D: The headache is caused by sinusitis.

Answer: D is correct.

Explanation : Headaches can be caused by a variety of factors, including sinusitis, which is inflammation of the sinuses. Inflammation in the shoulder is not likely to be the cause of a headache.

Scenario 4:

A patient is experiencing difficulty with temperature discrimination and has recently undergone a surgery on their spine. What could be causing the difficulty with temperature discrimination?

A: The patient has a neurological disorder.

B: The patient has a mental health condition.

C: The patient is experiencing a side effect of their medication.

D: The patient has interrupted the spinothalamic pathway.

Answer: D is correct.

Explanation : The spinothalamic pathway is crucial for pain and temperature discrimination. Interruption of this pathway can result in permanent deficits in these abilities. A surgical procedure on the spine could potentially interrupt the spinothalamic pathway and cause difficulty with temperature discrimination.

Scenario 5:

A patient is experiencing pain in their chest and has recently been diagnosed with inflammation in their lower leg. What could be causing the pain in the chest?

A: The patient is experiencing referred pain due to the inflammation in the lower leg.

B: The patient has a chest injury causing the pain.

C: The patient has a heart attack.

D: The patient has pneumonia.

Answer: C is correct.

Explanation : Chest pain can be a symptom of a heart attack, which is a medical emergency that requires immediate attention. Inflammation in the lower leg is not likely to be the cause of chest pain.

Scenario 6:

A patient is experiencing pain in their lower back and has recently been diagnosed with inflammation in their upper arm. What could be causing the pain in the lower back?

A: The patient is experiencing referred pain due to the inflammation in the upper arm.

B: The patient has a lower back injury causing the pain.

C: The patient has a kidney infection.

D: The patient has a spinal cord injury.

Answer: B is correct.

Explanation : Lower back pain can be caused by a variety of factors, including injury to the lower back. Inflammation in the upper arm is not likely to be the cause of lower back pain.

Scenario 7:

A patient is experiencing difficulty with pain perception and has recently undergone a surgery on their thalamus. What could be causing the difficulty with pain perception?

A: The patient has a neurological disorder.

B: The patient has a mental health condition.

C: The patient is experiencing a side effect of their medication.

D: The patient has interrupted the pathways that transmit pain signals to the cerebral cortex.

Answer: D is correct.

Explanation : The thalamus is involved in the transmission of pain signals to the cerebral cortex, and a surgical procedure on the thalamus could potentially interrupt these pathways and cause difficulty with pain perception.

Scenario 8:

A patient is experiencing pain in their abdomen and has recently been diagnosed with inflammation in their foot. What could be causing the pain in the abdomen?

A: The patient is experiencing referred pain due to the inflammation in the foot.

B: The patient has an abdominal injury causing the pain.

C: The patient has appendicitis.

D: The patient has a stomach ulcer.

Answer: C is correct.

Explanation : Abdominal pain can be caused by a variety of factors, including appendicitis, which is inflammation of the appendix. Inflammation in the foot is not likely to be the cause of abdominal pain.

Scenario 9:

A patient is experiencing pain in their neck and has recently been diagnosed with inflammation in their hand. What could be causing the pain in the neck?

A: The patient is experiencing referred pain due to the inflammation in the hand.

B: The patient has a neck injury causing the pain.

C: The patient has a spinal cord injury.

D: The patient has a neck muscle strain.

Answer: B is correct.

Explanation : Neck pain can be caused by a variety of factors, including injury to the neck. Inflammation in the hand is not likely to be the cause of neck pain.

Scenario 10:

A patient is experiencing pain in his jaw and has recently been diagnosed with inflammation in their elbow. What could be causing the pain in the jaw?

A: The patient is experiencing referred pain due to the inflammation in the elbow.

B: The patient has a jaw injury causing the pain.

C: The patient has temporomandibular joint (TMJ) disorder.

D: The patient has a tooth abscess.

Answer: C is correct.

Explanation : Jaw pain can be caused by a variety of factors, including temporomandibular joint (TMJ) disorder, which is a condition that affects the joint that connects the jaw to the skull. Inflammation in the elbow is not likely to be the cause of jaw pain.

Scenario 11:

A patient is experiencing numbness in their hand and has recently undergone a surgery on their spinal cord. What could be causing the numbness in the hand?

A: The patient has a neurological disorder.

B: The patient has a mental health condition.

C: The patient is experiencing a side effect of their medication.

D: The patient has interrupted the pathways that transmit sensation to the hand.

Answer: D is correct.

Explanation : The spinal cord is involved in the transmission of sensation to the hand, and a surgical procedure on the spinal cord could potentially interrupt these pathways and cause numbness in the hand.

Scenario 12:

A patient is experiencing pain in his eye and has recently been diagnosed with inflammation in their knee. What could be causing the pain in the eye?

A: The patient is experiencing referred pain due to the inflammation in the knee.

B: The patient has an eye injury causing the pain.

C: The patient has a corneal ulcer.

D: The patient has glaucoma.

Answer: B is correct.

Explanation : Eye pain can be caused by a variety of factors, including injury to the eye. Inflammation in the knee is not likely to be the cause of eye pain.

Scenario 13:

A patient is experiencing pain in her ear and has recently been diagnosed with inflammation in their ankle. What could be causing the pain in the ear?

A: The patient is experiencing referred pain due to the inflammation in the ankle.

B: The patient has an ear injury causing the pain.

C: The patient has an ear infection.

D: The patient has a foreign object stuck in their ear.

Answer: C is correct.

Explanation : Ear pain can be caused by a variety of factors, including ear infections. Inflammation in the ankle is not likely to be the cause of ear pain.

Scenario 14:

A patient is experiencing pain in her hip and has recently undergone a surgery on their somatosensory cortex. What could be causing the pain in the hip?

A: The patient has a hip injury causing the pain.

B: The patient has arthritis.

C: The patient has a muscle strain.

D: The patient has interrupted the pathways that transmit pain signals to the somatosensory cortex.

Answer: A is correct.

Explanation : Hip pain can be caused by a variety of factors, including injury to the hip. A surgical procedure on the somatosensory cortex, which is involved in the perception of sensation, is not likely to be the cause of hip pain.

Dr. Arin Nandi

Passionate About Medical Science & Helping Future Doctors Achieve Top Ranks In Medical Exams. He is professionally a dentist as well as a public health expert from JIPMER working in govt.health department
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