Modulation of the pain pathways

Question 1

Can tract cells be influence by non-noxious sensory stimuli?

Answer 1

Yes tract cells can be influenced by non-noxious sensory stimuli resulting in modification of pain perception

Question 2

How does pain travel from peripheral stimulus to the perception of pain?

Answer 2

Pain travels from the stimulus through the peripheral process to the central processes that terminate on secondary neurons (tract cells) in the dorsal horn. THe tract cells project fibers to the thalamus via the contralateral spinothalmic tract. Pain impulses are then relayed to the crotex for perception of the pain

Question 3

How does rubbing the area of painful stimulus modify pain?

Answer 3

Rubbing the area of a painful stimulus activates touch and pressure receptors supplied by primary afferent neurons

Question 4

Where do touch and pressure afferent fibers of the dorsal roots terminate?

Answer 4

Touch and pressure afferent fibers of the dorsal roots have collaterals that terminate on neurons in lamina II of the dorsal horn (substantia gelatinosa)

Question 5

What type of neurons are substantia gelatinosa?

Answer 5

They are inhibitory interneurons that can inhibit tract cells of the pain pathway

Question 6

Can touch and pressure stimuli activate inhibitory interneurons and modulate the transmission of pain data?

Answer 6

Yes touch and pressure stimuli can activate inhibitory interneurons that inhibit tract cells of the pain pathway and modulate the transmission of data in the ascending pathway

Question 7

What is the gate control theory?

Answer 7

Explaining the mechanism for the control of pain transmission and modulation

Question 8

What other sensory stimuli can modify pain transmission?

Answer 8

Modest temperature and proprioceptive stimulus

Question 9

Can modification of the pain pathways occur at other sites in the CNS?

Answer 9

Yes it can occur at the pars caudalis of the spinal trigeminal nucleus, thalamus and the cerebral cortex

Question 10

Can descending pathways in the CNS modulate the transmission of paid data in the dorsal horn of the brainstem?

Answer 10

Yes, through corticospinal fibers and reticulospinal fibers

Question 11

What are reticulospinal fibers?

Answer 11

Descending noxious modulatory pathways

Named as reticular formation in the brainstem but axons in the spinal cord can modulate pain transmission

Question 12

How is the integrity of the anterolateral system tested?

Answer 12

Test for pain
Test for temperature
Test for Crude Touch

Question 13

How is pain tested?

Answer 13

Pin-prick test with eyes closed which tests skin sensation and looks for normal responses (sharp is sharp) or abnormal responses (Dull is sharp)

Question 14

How are tests for temperature conducted?

Answer 14

Test tubes of warm or cool water

Question 15

How are tests for crude touch conducted?

Answer 15

Wisp of cotton

Question 16

What is parethesia

Answer 16

Abnormal sensations, tingling, itchin, burning, pins and needles

Question 17

What is Anesthesia?

Answer 17

Loss of all somatosensation for an area of the body

Question 18

What is analgesia?

Answer 18

Absence of pain in response to a stimulus which is normally painful stimuli

Question 19

What can mechanical compression do to nerves?

Answer 19

Can cause inflammation of peripheral nerve fibers and stimulate pain but can also cause paresthesia

Question 20

What is syringomyelia?

Answer 20

Degenerative condition characterized by cavitation of the central part of the spinal cord that disrupts area of the anterior white commissure

Question 21

Where does syringomyelia usually occur?

Answer 21

Often occurs in the cervical enlargement of the cord

Question 22

What are the sensory impariments included with syringomyelia?

Answer 22

Loss of pain and temperature sensations and analgesia to both and motor loss can also occur if degeneration extends to the ventral horn

Question 23

What is the lateral medullary syndrome also known as?

Answer 23

Wallenberg’s syndrome

Question 24

What is the lateral medullary syndrome ?

Answer 24

Caused by loss of blood supply to the lateral medulla (usually 1 side)

Question 25

What areas are disturbed with lateral medullary syndrome

Answer 25

Area of infarct disturbs many brainstem structures but includes the spinothalamic tract and the spinal trigeminal nucleus and tract

Question 26

What somatosensory impariments occur with lateral medullary syndrome?

Answer 26

Loss of pain and temperature sensation and analgesia to ipsilateral face (spinal thalamic tract) and the contralateral half of the body