Somatosensation: Clinical Application

Question 1

Allodynia

Answer 1

Sensation of pain in response to normally nonpainful stimuli

Question 2

Antinociception

Answer 2

Top-down inhibition of pain signals

Question 3

Chronic Pain Syndrome

Answer 3

Physiologic impairment consisting of muscle guarding, abnormal mov’ts, and disuse syndrome

Question 4

Complex Regional Pain Syndrome (CRPS)

Answer 4

A chronic syndrome of pain, vascular changes, and atrophy in a regional distribution
aka: causalgia, Sudeck’s atrophy, sympathetically maintained pain, reflex sympathetic dystrophy

Question 5

Counterirritant Theory

Answer 5

Theory that inhibition of nociceptive signals by stimulation of non-nociceptive receptors occurs in the dorsal horn of the SC

Question 6

Deafferntation

Answer 6

Interruption of sensory info from part of the body, usually caused by a lesion affecting first-order somatosensory neurons

Question 7

Dorsal Rhizotomy

Answer 7

Surgical severance of selected dorsal roots

Purpose = decrease pain or hyperreflexia

Question 8

Dysethesia

Answer 8

Painful abnormal sensation, including burning and aching sensations

Question 9

Ectopic Foci

Answer 9

Site of neural membrane that is abnormally sensitive to mechanical stimulation

Question 10

Endorphins

Answer 10

Endogenous, or naturally occurring, substances that activate analgesic mechanisms
- Include enkephalins, dynorphin, B-endorphin

Question 11

Enkephalin

Answer 11

A NT that, when bound to receptor sites, depresses the release of substance P and hyperpolarizes interneurons in the nociceptive pathway
- thus inhibiting the transmission of nociceptive signals

Question 12

Ephaptic Transmission

Answer 12

Cross-excitation of axons, caused by loss of myelin

- excitation of one axon induces activity in a parallel axon

Question 13

Fibromyalgia

Answer 13

Tenderness of muscles and adjacent soft tissues, stiffness of muscles, and aching pain
- the painful area shows a regional rather than dermatomal or peripheral nerve distribution

Question 14

Gate Theory of Pain

Answer 14

Theory that transmission of pain info can be blocked in the dorsal horn by stimulation of large-fiber primary afferent neurons

Question 15

Locus Ceruleus

Answer 15

Nucleus in the upper pons involved in direction ofr attention, nonspecific activation of interneurons and lower motor neurons in the SC, and inhibition of pain info in the dorsal horn
- Transmitter produced is nor-epinephrine

Question 16

Migraine

Answer 16

Syndrome including headache, nausea, vomiting, extreme sensitivity to light and sound, dizziness, and cognitive disturbances

• caused by inherited abnormalities in genes that control activity of certain BS neurons
• Some do not include headache or are preceded by an aura

Question 17

Myofascial Pain

Answer 17

pressure on sensitive points (trigger points) reproduces the person’s pattern of referred pain

• advocates contend that the dx is confirmed when stretching or injecting a local anesthetic into the trigger points eliminates the pain
• controversial diagnosis

Question 18

Neuropathic Chronic Pain

Answer 18

persistent pain caused by abnormal neural activity in various locations in the NS

Question 19

Neuropathy

Answer 19

dysfunction or pathologic condition of one or more peripheral nerves

Question 20

Nociceptive Chronic Pain

Answer 20

Persistent pain caused by stimulation of nociceptive receptors

Question 21

Paresthesia

Answer 21

Nonpainful abnormal sensation, often described by pricking and tingling

Question 22

Periaqueductal Gray

Answer 22

Area around the cerebral aqueduct in the midbrain

• involved in somatic and autonomic rxns to pain, threats, and emotions
• activity of the periaqueductal gray results in the fight-or-flight rxn and in vocalization during laughing/crying

Question 23

Peripheral Nerve Distribution

Answer 23

Area of skin innervated by a single peripheral nerve

Question 24

Postherpetic Neuralgia

Answer 24

Severe pain that persists more than 1 month after an infection with varicella zoster virus
- occurs along the distribution of a peripheral nerve or branch of a peripheral nerve

Question 25

Pronociception

Answer 25

Biologic amplification of pain signals

Question 26

Raphe nuclei

Answer 26

BS nuclei that modulate activity throughout the CNS

• Major source of serotonin
• Midbrain nuclei = Important in mood regulation & onset of sleep
• Pontine nuclei = modulate activity in BS and cerebellum
• Medullary nuclei = modulate activity in the SC via raphespinal tracts
• Projections to the SC inhibit transmission of nociceptive info, adjusting levels of interneuron activity, producing nonspecific activation of lower motor neurons

Question 27

Referred Pain

Answer 27

Pain that is perceived as arising in a site different from the actual site producing the nociceptive info

Question 28

Sensory Extinction

Answer 28

A form of unilateral neglect

- Loss of sensation is evident only when symmetrical body parts are test bilaterally

Question 29

Tinel’s sign

Answer 29

A sensation of pain or tingling in the distal distribution of a peripheral nerve
- elicited by tapping on the skin over an injured nerve

Question 30

Varicella zoster

Answer 30

infection of a dorsal root ganglion or CN ganglion with varicella zoster virus
aka herpes zoster