Modulation of the pain pathways Flashcards
Can tract cells be influence by non-noxious sensory stimuli?
Yes tract cells can be influenced by non-noxious sensory stimuli resulting in modification of pain perception
How does pain travel from peripheral stimulus to the perception of pain?
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
How does rubbing the area of painful stimulus modify pain?
Rubbing the area of a painful stimulus activates touch and pressure receptors supplied by primary afferent neurons
Where do touch and pressure afferent fibers of the dorsal roots terminate?
Touch and pressure afferent fibers of the dorsal roots have collaterals that terminate on neurons in lamina II of the dorsal horn (substantia gelatinosa)
What type of neurons are substantia gelatinosa?
They are inhibitory interneurons that can inhibit tract cells of the pain pathway
Can touch and pressure stimuli activate inhibitory interneurons and modulate the transmission of pain data?
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
What is the gate control theory?
Explaining the mechanism for the control of pain transmission and modulation
What other sensory stimuli can modify pain transmission?
Modest temperature and proprioceptive stimulus
Can modification of the pain pathways occur at other sites in the CNS?
Yes it can occur at the pars caudalis of the spinal trigeminal nucleus, thalamus and the cerebral cortex
Can descending pathways in the CNS modulate the transmission of paid data in the dorsal horn of the brainstem?
Yes, through corticospinal fibers and reticulospinal fibers
What are reticulospinal fibers?
Descending noxious modulatory pathways
Named as reticular formation in the brainstem but axons in the spinal cord can modulate pain transmission
How is the integrity of the anterolateral system tested?
Test for pain
Test for temperature
Test for Crude Touch
How is pain tested?
Pin-prick test with eyes closed which tests skin sensation and looks for normal responses (sharp is sharp) or abnormal responses (Dull is sharp)
How are tests for temperature conducted?
Test tubes of warm or cool water
How are tests for crude touch conducted?
Wisp of cotton
What is parethesia
Abnormal sensations, tingling, itchin, burning, pins and needles
What is Anesthesia?
Loss of all somatosensation for an area of the body
What is analgesia?
Absence of pain in response to a stimulus which is normally painful stimuli
What can mechanical compression do to nerves?
Can cause inflammation of peripheral nerve fibers and stimulate pain but can also cause paresthesia
What is syringomyelia?
Degenerative condition characterized by cavitation of the central part of the spinal cord that disrupts area of the anterior white commissure
Where does syringomyelia usually occur?
Often occurs in the cervical enlargement of the cord
What are the sensory impariments included with syringomyelia?
Loss of pain and temperature sensations and analgesia to both and motor loss can also occur if degeneration extends to the ventral horn
What is the lateral medullary syndrome also known as?
Wallenberg’s syndrome
What is the lateral medullary syndrome ?
Caused by loss of blood supply to the lateral medulla (usually 1 side)
What areas are disturbed with lateral medullary syndrome
Area of infarct disturbs many brainstem structures but includes the spinothalamic tract and the spinal trigeminal nucleus and tract
What somatosensory impariments occur with lateral medullary syndrome?
Loss of pain and temperature sensation and analgesia to ipsilateral face (spinal thalamic tract) and the contralateral half of the body
