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

Clinical Application of Somatosensation Flashcards

1
Q

Somatosensation is essential for what?

A

The accurate control of movements and protection against injury

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2
Q

What are the 4 pathways necessary to test for somatosensation?

A
  • Discriminative touch
  • Conscious proprioception
  • Fast pain
  • Discriminative temperature
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3
Q

What does quick screening for sensory impairment consist of?

A

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

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4
Q

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

A

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

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5
Q

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

A

recording electrical activity from nerves

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6
Q

What are 2 methods of examining sensory nerve function?

A
  • Nerve conduction studies (NCSs)

- Somatosensory-evoked potentials (SEPs)

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7
Q

What do nerve conduction studies evaluate?

A

The function of peripheral nerves

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8
Q

How are NCS and SEP applied?

A

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

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9
Q

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

A

large

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10
Q

Conduction velocity is slowed in what types of nerves?

A

demyelinated ones

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11
Q

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

A
  • Distal latency
  • Amplitude of the evoked potential
  • Conduction velocity
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12
Q

What is distal latency?

A

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

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13
Q

What do somatosensory-evoked potentials evaluate?

A

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

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14
Q

What are SEPs used to verify?

A

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

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15
Q

What is ataxia?

A

Incoordination that is not the result of weakness

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16
Q

What are the 3 types of ataxia?

A
  • sensory
  • vestibular
  • cerebellar
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17
Q

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

A

Romberg test

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18
Q

What is neuropathy?

A

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

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19
Q

What does complete severance of a peripheral nerve result in?

A

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

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20
Q

What does compression of a peripheral nerve result in?

A

Decreased sensation or a feeling of a limb “falling asleep”

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21
Q

Describe the order in which sensory loss proceeds

A

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

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22
Q

What occurs when compression is relieved?

A

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

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23
Q

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

A
  • 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
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24
Q

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

A

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

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25
Q

Describe sensory loss following a hemisection of the spinal cord

A
  • 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
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26
Q

What sensations are lost in posterior column lesions?

A

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

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27
Q

What occurs immediately after a posterior column lesion?

A

Movements are ataxic

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28
Q

What may occur in a posterior column lesion above C6?

A

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

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29
Q

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

A

Varicella zoster (aka shingles)

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30
Q

What is the major symptom of shingles?

A

severe pain

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31
Q

Do brainstem lesions causes ipsilateral and contralateral signs?

A

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

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32
Q

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

A

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

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33
Q

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

A

An ipsilateral loss of sensation from the face

34
Q

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

A

contralateral

ipsilateral

35
Q

What do thalamic lesions result in?

A

Decreased or lost sensation from the contralateral body or face

36
Q

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

A

They rarely do

37
Q

What does a lesion of the somatosensory cortex result in?

A

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
Q

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

A

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
Q

What is pain often associated with?

A

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

40
Q

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

A

perception

41
Q

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

A

peripheral sensitization

42
Q

Unlike superficial pain, when does deep pain usually occur?

A

After the tissue has been damaged

43
Q

What is the function of deep pain?

A

To encourage rest of the damaged tissue

44
Q

What is referred pain?

A

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

45
Q

When does referred pain occur?

A

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
Q

What does the pain matrix consist of?

A

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

47
Q

What brain structures does the pain matrix include?

A

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

48
Q

What is the experience of pain strongly linked to?

A

emotional, behavioral, and cognitive phenomena

49
Q

What does the discriminative aspect of pain refer to?

A

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

50
Q

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

A

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

51
Q

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

A

The meaning that the person ascribes to the pain

52
Q

Describe the gate theory of pain

A

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

53
Q

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

A

in the dorsal horn of the spinal cord

54
Q

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

A

The Counterirritant Theory

55
Q

What are the 4 states of dorsal horn processing?

A
  • Normal
  • Suppressed
  • Sensitized
  • Reorganized
56
Q

Describe the mechanism of suppressed sensory processing in the dorsal horn

A

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

57
Q

Describe the mechanism of sensitized sensory processing in the dorsal horn

A

There are changes in neurotransmitters and receptors

58
Q

Describe the mechanism of reorganized sensory processing in the dorsal horn

A

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
Q

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

A

Sensitized and Reorganized

60
Q

What does neuropathic pain result from?

A

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

61
Q

What is Antinociception?

A

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

62
Q

What are the substances that activate antinociceptive mechanisms?

A

Endorphins

63
Q

Endorphins bind to what kind of receptor?

A

Opiate receptors

64
Q

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

A

five

65
Q

Where does level 1 of antinociception occur?

A

in the periphery

66
Q

Where does level 2 of antinociception occur?

A

in the dorsal horn

67
Q

What is level 3 called?

A

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

68
Q

What is level 4 called?

A

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

69
Q

Level 5 is the _____ level

A

cortical

70
Q

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

A

Level 2

71
Q

At what level does low-rate TENS act on?

A

Level 4

72
Q

What is pronoception?

A

The biological amplification of pain signals

73
Q

What is the mechanism of pronoception?

A

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

74
Q

What causes acute pain?

A

Threat or actual tissue damage

75
Q

How does a client report acute pain?

A

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

76
Q

What is the function of acute pain?

A

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

77
Q

What are the causes of chronic pain?

A
  • Continuing tissue damage
  • Environmental factors
  • Sensitization of nociceptive pathway neurons
  • Dysfunction of endogenous pain control systems
78
Q

How does a client report chronic pain?

A

They give very vague descriptions

79
Q

What is the function of chronic pain?

A

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

80
Q

What is nociceptive chronic pain due to?

A

continuing stimulation of nociceptive receptors

81
Q

What is an example of nociceptive chronic pain?

A

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

82
Q

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

A

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

632: Neuroanatomy-Neuroscience (26 decks)

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