Somatosensory System And Chronic Pain

Question 1

Nocioreceptors

Answer 1

Receptors that respond only to noxious stimuli and generate nerve impulses that the brain interprets as pain

Question 2

Slow adapting fibres

Answer 2

Fire continuously so long as pressure is applied
Primary functions are detection and perception of fine detail and texture

Question 3

Rapidly adapting fibres

Answer 3

Fire at the onset and offset of pressure
Primary functions are low and high frequency vibration detection

Question 4

Temperature detection

Answer 4

The neural processing of temperature is closely related to that of pain; The sensation of cold can inhibit the sensation of pain, and it seems to be gated similarly to pain too (stimulating nearby cold+warm spots produces a feeling of intense heat).
The cold receptors code for extreme temperatures, not just cold, so when we feel cold and warmth, we interpret it as extreme and warmth, and feel extreme heat - (Craig, Reiman, Evans & Bushnell, 1996).

Question 5

Acute pain

Answer 5

Constitutes a signal to the brain about the presence of noxious stimuli and/or ongoing tissue damage.
It has an important biological and a distinct protective function.
Has a sudden onset and often lasts from days to weeks but it resolves during the healing process.
Is useful as the individual is informed about danger and the need to escape or seek help.
Is often experienced during trauma, surgery or illness.
Poorly controlled acute pain can be a factor leading to progression towards chronic pain.
That’s why early and efficient management of pain is important.

Question 6

Chronic pain

Answer 6

Persists after the damaged tissue is healed and has no biological function.
Chronic pain is associated with functional, structural or chemical changes in the pain detection system itself, thus putting it into the realm of a disease in its own right.
In addition, chronic pain often sets the stage for the emergence of a complex set of physical and psychosocial changes.
In clinical practice acute and chronic pain often do not represent two clearly separate entities.
They may constitute a continuum without a clear boundary.

Question 7

Cancer pain

Answer 7

Is a complex, temporally changing symptom which is the end result of mixed mechanism.
It involves inflammatory, neuropathic, ischaemic and compression mechanism at multiple sites.
It is a subjective, heterogenous experience that is modified by individual genetics, past history, mood, expectation, and culture.
In clinical practice it can present as acute and chronic pain.
As there is often a limited life expectancy, destructive treatment are considered to be an option (e.g. cordotomy).

Question 8

Neuropathic pain

Answer 8

Damage or central or peripheral nervous system
Pain caused by a lesion or disease in the somatosensory nervous system

Question 9

How common is chronic pain?

Answer 9

20% of patients have some kind of chronic pain

Question 10

Peripheral neuropathy pain

Answer 10

Pain caused by a lesion or disease of the peripheral somatosensory nervous system

Question 11

Central neuropathic pain

Answer 11

Pain caused by a lesion or disease of the central somatosensory nervous system

Question 12

Hyperalgesia

Answer 12

Increased pain from a stimulus that normally provokes pain

Question 13

Hypoalgesia

Answer 13

Diminished pain in response to a stimulus that normally causes pain

Question 14

Allodynia

Answer 14

Pain due to a stimulus that does not normally provoke pain

Question 15

Hyperpathia

Answer 15

Painful syndrome characterised by a abnormal painful reaction to a stimulus, especially a repetitive stimulus, as well as an increased threshold