Clinical application for Somatosensation

Question 1

What is the purpose of a sensory exams? (cover conscious relay pathways)

Answer 1

establish whether sensory impairment is present and, if so, the location, type of sensation affected, and severity of the deficit

Question 2

What are the 6 guidelines to improve the reliability of sensory testing?

Answer 2

1. Administer tests in a quiet, distraction-free setting.
2. Position the patient seated or lying supported by a firm, stable surface to avoid challenging balance.
3. Explain the purpose of the test.
4. Demonstrate each test before administering.
5. Block the patient’s vision during the tests.
6. Apply stimuli near the center of the dermatomes being tested.

Question 3

What does the quick screening for somatosensation include?

Answer 3

1. Testing proprioception and vibration in the fingers and toes
2. Testing fast pain sensation in the limbs, trunk, and face with a pinprick

Question 4

What distribution of losses would be seen in a stroke or neuropathy?

Answer 4

body region

Question 5

What distribution of losses would be seen in a nerve root or spinal cord injury?

Answer 5

Dermatome

Question 6

What distribution of losses would be seen in a peripheral nerve injury?

Answer 6

Peripheral nerve distribution

Question 7

What are the two methods for electrodiagnostic studies?

Answer 7

1. Nerve conduction study

2. Somatosensory-evoked potentials

Question 8

Measures peripheral nerve function; Stimulating in the periphery and recording in the periphery; surface recording electrodes are placed along the course of a peripheral nerve, and the nerve is electrically stimulated

Answer 8

Nerve conduction study (NCS)

Question 9

Tests peripheral nerves and CNS pathways; Stimulating in the periphery and recording in the CNS

Answer 9

Somatosensory-evoked potentials

Question 10

What type of nerves are you looking at when doing a NCS?Why are they performed?

Answer 10

Large-diameter fibers; to see if there is a loss of myelination

Question 11

To determine if an NCS is normal, what three numerical values are compared?

Answer 11

1. Distal latency
2. Amplitude of the evoked potential - measure of how many axons carry a signal
3. Conduction velocity- measure of myelination

Question 12

What test would you use to localize a peripheral nerve problem (myelination, or compression due to carpal tunnel)?

Answer 12

Nerve Conduction Study

Question 13

Evaluate the function of the pathway from the periphery to the upper spinal cord or to the cerebral cortex; Potentials are used to verify subtle signs and locate lesions of the dorsal roots, posterior columns, and brainstem

Answer 13

Somatosensory-Evoked potentials

Question 14

What are the three types of ataxia?

Answer 14

1. Sensory
2. Vestibular
3. Cerebellar

Question 15

Test that is used to distinguish between cerebellar ataxia and sensory ataxia. How do you distinguish between sensory and cerebellar ataxia?

Answer 15

Romberg test

• cerebellar = unable to perform with eyes open or closed
• sensory = can perform with eyes open, but not closed

Question 16

What three systems are there to maintain balance?

Answer 16

1. Visual
2. Vestibular
3. Proprioception (sensory)

Question 17

general term for dysfunction or the pathologic condition of one or more peripheral nerves

Answer 17

neuropathy

Question 18

What will be there result of a severance of a peripheral nerve?

Answer 18

1. Lack of sensation in the distribution of the nerve (pain, touch, proprioception)
2. Pain may occur (can’t feel stimuli but changes occurring cause pain or tingling in a body part)
3. Sensory changes are accompanied by motor and reflex loss

Question 19

What is the order of sensory losses that proceed pressure, compression or injury?

Answer 19

Starts with the fastest axons and goes to the slowest:

1. Conscious proprioception and discriminative touch
2. Cold
3. Fast pain
4. Heat
5. Slow pain

Question 20

What are common causes of dysfunction in spinal region?

Answer 20

1. Trauma to the spinal cord and complete or partial severing of the cord
2. Disease that compromises the function of specific areas in the spinal cord
3. Virus that infects the dorsal root ganglion

Question 21

Lesion that results in:

All sensation is prevented at one or two levels below the lesion; Voluntary motor control below the lesion is also lost

Answer 21

Transection of the cord

Question 22

Lesion that results in:
(Spinothalamic) Complete loss of pain sensation occurs two to three dermatomes below the level of the lesion contralateral to the lesion.
(DCML) Discriminative touch and conscious proprioception are lost ipsilateral to the lesion

Answer 22

Hemisection of the cord (Brown-sequard)

Question 23

Lesion that results in:

• Conscious proprioception, two-point discrimination, and vibration sense are lost below the level of the lesion.
• Movements are ataxic immediately after the lesion.
• Individual may be unable to recognize objects by palpation if the lesion is above C6

Answer 23

Posterior Column Lesions

causes - untreated syphillis, extension injury

Question 24

Syndrome that results from:
Disrupts spinothalamic fibers that are crossing the midline
Usually occurs in cervical spinal cord; With small lesion, only pain and temperature sensation are lost at level of injury. what pattern does this create?

Answer 24

Central cord syndrom; cape pattern

Question 25

What is the region that spinothalamic fibers cross?

Answer 25

Ventral white commissure

Question 26

What can cause central cord syndrome?

Answer 26

1. Syringomyelia | 2. Trauma

Question 27

What side do brainstem region lesions affect?

Answer 27

- Usually cause a mix of ipsilateral and contralateral signs - Sensory loss may be entirely contralateral only in the upper midbrain after all discriminative sensation tracts have crossed the midline. - Lesions of the trigeminal nerve proximal axons or of the trigeminal nerve nuclei cause an ipsilateral loss of sensation from the face AKA Wallenberg syndrome

Question 28

Sensory effects of a cortical lesion are contralateral and include decreased or loss of discriminative sensations: Conscious proprioception, Two-point discrimination, Stereognosis, Localization of touch and pinprick (nociceptive) stimuli [still feel pain and temp but trouble localizing]

Answer 28

Somatosensory cortex lesions

Question 29

a form of unilateral neglect because the person neglects stimuli on one side of the body when the other side of the body is stimulated simultaneously; the loss of sensation is only evident when symmetrical body parts are tested bilaterally

Answer 29

sensory extinction

Question 30

What is pain often associated with?

Answer 30

- Tissue damage or potential tissue damage Pain is a perception

Question 31

What sensitizes nociceptors?

Answer 31

When tissue is injured or ischemic, biochemicals are released -Sensitized neurons can fire in response to normally innocuous stimuli, with slight movements, and spontaneously

Question 32

Nociceptors that are excessively reactive to stimuli are called

Answer 32

peripheral sensitization

Question 33

Unlike superficial pain, deep pain usually occurs after tissue has been damaged. What is the function of deep pain?

Answer 33

Encourage rest of the damaged tissue

Question 34

Pain that is perceived as coming from a site distinct from the actual site of origin; usually from visceral tissues to the skin

Answer 34

Referred pain -Explanation comes from the convergence and facilitation of nociceptive information from different sources

Question 35

Consists of brain structures that process and regulate pain information and are capable of creating pain perception in the absence of nociceptive input; Includes parts of the brainstem, amygdala, hypothalamus, thalamus, and areas of the cerebral cortex

Answer 35

Pain matrix

Question 36

Experience of pain is strongly linked to emotional, behavioral, and cognitive phenomena. Understanding requires the consideration of ______, _______, and ______ components

Answer 36

discriminative; motivational-affective; cognitive-evaluative

Question 37

_______ aspect refers to the ability to localize the site, timing, and intensity of tissue damage or potential tissue damage

Answer 37

Discriminative

Question 38

________ aspect refers to the effects of the pain experience on emotions and behavior, including increased arousal and avoidance behavior

Answer 38

Motivational-affective

Question 39

_______ aspect refers to the meaning that the person ascribes to the pain

Answer 39

Cognitive-evaluative

Question 40

What happens if you inure the anterior cingulate cortex?

Answer 40

it can block emotional aspects of pain but leave discrimination intact

Question 41

First scientific explanation of how pressure and other external stimuli inhibit pain transmission (holding your thumb when you hit it with a hammer), proposed by Melzack and Wall in 1965. Some details are incorrect, but it inspired inquiry into the mechanics and control of pain, such as TENS. theory of suppressed dorsal horn processing

Answer 41

Gate Theory

Question 42

Theory: explains the inhibition of nociceptive signals by stimulation of non-nociceptive receptors occurs in the dorsal horn of the spinal cord; theory of suppressed dorsal horn processing

Answer 42

Counterirritant theory

Question 43

What are the four states of dorsal horn processing?

Answer 43

1. Normal 2. Suppressed (50 come in, 20 go up - perceive less pain) 3. Sensitized (50 come in, 100 go up - perceive more pain) 4. Reorganized (pathological, changing the underlying structure of connections - can start happening with in 2 days of pain)

Question 44

the suppression of pain in response to stimulation that would normally be painful

Answer 44

Antinociception

Question 45

endogenous substances that activate antinociceptive mechanisms

Answer 45

endorphines

Question 46

What do opiate receptors bind with?

Answer 46

endorphins and opiates

Question 47

Due to continuing stimulation of nociceptive receptors; Neurons are functioning normally; chemical changes in the damaged tissue awaken sleeping peripheral nociceptors; long-term acute pain; serves a useful biological function as a warning to protect injured tissue

Answer 47

Nociceptive chronic pain

Question 48

Increased pain response (sensation of pain); painful input is perceived as more painful

Answer 48

primary hyperalgesia

Question 49

what is essential for two-point discrimination, paresthesia, stereognosis, and simultaneous awareness of stimulation on both sides of the body

Answer 49

primary somatotsensory cortex

Question 50

What will a proprioceptive pathway lesion result in?

Answer 50

sensory ataxia

Question 51

What cell bodies do the periaquductal gray synapse with? where are they located? what are the postsynaptic axon tracts called?

Answer 51

1. Locus coeruleus - midbrain and pons; ceruleospinal tract | 2. Raphe nuclei - medulla, specifically rostral ventromedial medulla; raphespinal tract

Question 52

What are the different antinociceptive systems? how do they block nociceptive input?

Answer 52

I. Peripheral - block sensitization in nociceptors II. Dorsal horn - Gate/ counterirritant theory III. PAG - activate inhibitory interneurons at dorsal horn IV. Hormonal - Release of ACTH at pituitary; slower but longer analgesia; low frequency TENS activates system V. Descending cortical inhibition - Cognitive meaning; distraction of pain, expectations of pain

Question 53

What may cause pronociception?

Answer 53

- edema and endogenous chemicals sensitize free nerve endings - anxiousness or depression