Clinical Application of Somatosensation Flashcards Preview

632: Neuroanatomy-Neuroscience > Clinical Application of Somatosensation > Flashcards

Flashcards in Clinical Application of Somatosensation Deck (82):
1

Somatosensation is essential for what?

The accurate control of movements and protection against injury

2

What are the 4 pathways necessary to test for somatosensation?

- Discriminative touch
- Conscious proprioception
- Fast pain
- Discriminative temperature

3

What does quick screening for sensory impairment consist of?

Testing proprioception and vibration in the fingers and toes and testing past pain sensation in the limbs, trunk, and face with a pinprick

4

Do somatosensory tests test the ability to use somatosensation to prepare for and during movements?

No, they only require that the patient has conscious awareness and cognition

5

What is one way you can reveal the location of nerve pathologies?

recording electrical activity from nerves

6

What are 2 methods of examining sensory nerve function?

- Nerve conduction studies (NCSs)
- Somatosensory-evoked potentials (SEPs)

7

What do nerve conduction studies evaluate?

The function of peripheral nerves

8

How are NCS and SEP applied?

Electrical stimulation is applied to the peripheral nerve so that all axons are depolarized simultaneously

9

Nerve conduction studies only measure the performance of ___-diameter axons

large

10

Conduction velocity is slowed in what types of nerves?

demyelinated ones

11

What are the 3 numeric values that are compared in order to determine whether a NCS is normal

- Distal latency
- Amplitude of the evoked potential
- Conduction velocity

12

What is distal latency?

the time required for the depolarization evoked by the stimulus to reach the distal recording site

13

What do somatosensory-evoked potentials evaluate?

The function of the pathway from the periphery to the upper spinal cord or to the cerebral cortex

14

What are SEPs used to verify?

Subtle signs and locate lesions of the dorsal roots, posterior columns, and brainstem

15

What is ataxia?

Incoordination that is not the result of weakness

16

What are the 3 types of ataxia?

- sensory
- vestibular
- cerebellar

17

What test is used to distinguish between cerebellar ataxia and sensory ataxia?

Romberg test

18

What is neuropathy?

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

19

What does complete severance of a peripheral nerve result in?

Lack of sensation in the distribution of the nerve, pain may occur, and sensory changes are accompanied by motor and reflex loss

20

What does compression of a peripheral nerve result in?

Decreased sensation or a feeling of a limb "falling asleep"

21

Describe the order in which sensory loss proceeds

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

22

What occurs when compression is relieved?

Sensations are returned in the reverse order that they were lost. Thus, aching pain occurs first, then a sensation of warmth, then sharp, stinging sensations, then cold, and finally a return of discriminative touch and conscious proprioception

23

What are the 3 common causes of dysfunction of the spinal region?

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

24

Describe sensory and motor loss following a complete severing of the spinal cord

All sensation is lost at one of two levels below the lesion and all voluntary motor control is lost below the lesion

25

Describe sensory loss following a hemisection of the spinal cord

- There is reduced sensation of pain and temperature on the contralateral side two to three dermatomes below the level of the lesion
- There is reduced sensation of discriminative touch and conscious proprioception on the ipsilateral side of the lesion
- There is a zone of complete loss of sensation on the ipsilateral side of the lesion, just below it

26

What sensations are lost in posterior column lesions?

Conscious proprioception, two-point discrimination, and vibration sense are lost below the level of the lesion

27

What occurs immediately after a posterior column lesion?

Movements are ataxic

28

What may occur in a posterior column lesion above C6?

The individual may be unable to recognize objects by palpation because ascending information from the hand has been lost

29

Infection of a dorsal root ganglion or a cranial nerve ganglion causes what?

Varicella zoster (aka shingles)

30

What is the major symptom of shingles?

severe pain

31

Do brainstem lesions causes ipsilateral and contralateral signs?

A mix of the two because the axons that carry sensory information from the body and face cross the midline at various levels

32

A lesion at what point in the brainstem will sensory loss be entirely contralateral?

In the upper midbrain after all discriminative sensation tracts have crossed the midline

33

A lesion of trigeminal nerve proximal axons or of the trigeminal nerve nuclei causes what?

An ipsilateral loss of sensation from the face

34

Lesions in the brainstem often cause mixed sensory impairments, affecting the _____ body and ____ face

contralateral

ipsilateral

35

What do thalamic lesions result in?

Decreased or lost sensation from the contralateral body or face

36

Do those who experience thalamic lesions (stroke) have severe pain in the contralateral body or face?

They rarely do

37

What does a lesion of the somatosensory cortex result in?

Contralateral sensory effects that include decreased or loss of discriminate sensations such as conscious proprioception, two-point discrimination, stereognosis, and localization of touch and pinprick (nociceptive) stimuli

38

When is the only time in which somatosensory cortex lesions are evident?

When symmetrical body parts are tested bilaterally, so that the person neglects stimuli on one side of the body when the other side of the body is stimulated simultaneously (unilateral neglect)

39

What is pain often associated with?

tissue damage or potential tissue damage, although it can be experienced independently of tissue damage

40

Even though nociceptors signal injury, their activity is insufficient to cause pain because pain is a ______.

perception

41

When nociceptors are stimulated by biochemicals released from tissue that is injured or ischemic they become excessively reactive to stimuli, what is this called?

peripheral sensitization

42

Unlike superficial pain, when does deep pain usually occur?

After the tissue has been damaged

43

What is the function of deep pain?

To encourage rest of the damaged tissue

44

What is referred pain?

Pain that is perceived as coming from a site distinct from the actual site of origin

45

When does referred pain occur?

When branches of nociceptive fibers from an internal organ and branches nociceptive fibers from the skin converge on the same second-order neurons in the spinal cord or in the thalamus, and the central neurons become sensitized

46

What does the pain matrix consist of?

Brain structures that process and regulate pain information and are capable of creating pain perception in the absence of nociceptive input

47

What brain structures does the pain matrix include?

parts of the brainstem, amygdala, hypothalamus, thalamus, and areas of the cerebral cortex

48

What is the experience of pain strongly linked to?

emotional, behavioral, and cognitive phenomena

49

What does the discriminative aspect of pain refer to?

The ability to localize the site, timing, and intensity of tissue damage or potential tissue damage

50

What does the motivational-affective aspect of pain refer to?

The effects of the pain experience on emotions and behavior, including increased arousal and avoidance behavior

51

What does the cognitive-evaluative aspect of pain refer to?

The meaning that the person ascribes to the pain

52

Describe the gate theory of pain

If low-threshold mechanical afferents are more active than nociceptive afferents, mechanoreceptive information is transmitted and nociceptive information is inhibited.

53

According to the gate control theory of pain where is pain transmission blocked?

in the dorsal horn of the spinal cord

54

What theory incorporates findings from research stimulated by the gate theory?

The Counterirritant Theory

55

What are the 4 states of dorsal horn processing?

- Normal
- Suppressed
- Sensitized
- Reorganized

56

Describe the mechanism of suppressed sensory processing in the dorsal horn

Touch, pressure, and vibration information is transmitted normally, but pain impulses are inhibited

57

Describe the mechanism of sensitized sensory processing in the dorsal horn

There are changes in neurotransmitters and receptors

58

Describe the mechanism of reorganized sensory processing in the dorsal horn

The structure of the dorsal horn has changed owing to cell death, degeneration of nociceptive axon terminals, and the sprouting of new terminals that synapse with neurons in the nociceptive pathways

59

Of the 4 states of dorsal horn processing, which are neuropathic (pain causing)?

Sensitized and Reorganized

60

What does neuropathic pain result from?

changes in neuronal activity, thus by neuroplasticity not by stimulation of nociceptors.

61

What is Antinociception?

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

62

What are the substances that activate antinociceptive mechanisms?

Endorphins

63

Endorphins bind to what kind of receptor?

Opiate receptors

64

The phenomenon of antinociception is summarized by a ___-level model

five

65

Where does level 1 of antinociception occur?

in the periphery

66

Where does level 2 of antinociception occur?

in the dorsal horn

67

What is level 3 called?

The fast-acting neuronal descending system, involving PAG, the rostral ventromedial medulla, and the locus coeruleus

68

What is level 4 called?

the hormonal system, involving the PVG in the hypothalamus, the pituitary gland, and the adrenal medulla

69

Level 5 is the _____ level

cortical

70

At what level do superficial heat and high-rate TENS act on?

Level 2

71

At what level does low-rate TENS act on?

Level 4

72

What is pronoception?

The biological amplification of pain signals

73

What is the mechanism of pronoception?

Edema and endogenous chemicals sensitize free nerve endings in the periphery intensifying pain signals

74

What causes acute pain?

Threat or actual tissue damage

75

How does a client report acute pain?

They give a clear, description of location, pattern quality, frequency, and duration of pain

76

What is the function of acute pain?

Acts as warning of tissue damage to enforce rest of healing tissue

77

What are the causes of chronic pain?

- Continuing tissue damage
- Environmental factors
- Sensitization of nociceptive pathway neurons
- Dysfunction of endogenous pain control systems

78

How does a client report chronic pain?

They give very vague descriptions

79

What is the function of chronic pain?

If tissue damage is not continuing, there is no biological benefit, but there may be a social or psychosocial benefit

80

What is nociceptive chronic pain due to?

continuing stimulation of nociceptive receptors

81

What is an example of nociceptive chronic pain?

Chronic pain that results from a vertebral tumor pressing on nociceptors in the meninges surrounding the spinal cord

82

The chemical changes that occur in chronically damaged tissues activates peripheral nociceptors which leads to what?

Primary hyperalgesia which is an excessive sensitivity to stimuli in the injured tissue