Pain Flashcards
What are the names of receptors which sense pain?
Nociceptor
What substances can sensitise nociceptors?
Leukotrienes Substance P Noradrenaline Neurokinin A CRGP Nitric oxide Reactiev oxygen species Cytokines Prostaglandins
What types of fibres transmit painful stimuli?
A-delta and C fibres
Which ascending tract does painful stimuli follow to the brain?
Spinothalamic tract
Describe the gate control theory of pain
In the absence of input from C fibres, tonically active inhibitory interneurons suppress the pain pathway but with strong pain the C fibres can override this inhibitory neuron to allow a pain signal to be sent to the brain, however, pain can also be modulated by simultaneous somatosensory input
Describe the phenomenon of referred pain
The sensation of pain is experienced ay a site other than the injured or disease tissue. It occurs because both visceral and somatic afferents converge on the same neurons in the spinal cord. So input from the viscera may be ‘refer’ to the somatic source
What is hyperalgesia?
Increased sensitivity to painful simtuli
Describe the type of pain that occurs in non-specific low back pain
Characterised by tension, pain and stiffness particularly in the morning
usually short lived and self-limiting
usually varies with time and physical activity
How would non-specific low back pain, with no red flags, be managed?
Giving general information, education and advice
Analgesia - usually paracetamol and avoiding NSAIDs where possible
Patients advised to stay active and complete back exercises
What factors may contribute to the development and maintenance of chronic pain and disability (i.e. yellow flags)?
Belief that pain is harmful and disabling sickness behaviours i.e. extended rest social withdrawal problems at work emotional problems inappropriate expectations of treatment
Prolapse of the intervertebral disc involves the protrusion of the nucleus pulpous towards the intervertebral foramen. This is usually an anterior protrusion. T/F?
False- it is usually posterior
What red flag symptoms may indicate a more serious cause of back pain?
Systemic ailments (fever, night sweats)
history of malignancy or IV drug use
profound or progressive neurological deficit
sphincter disturbance (bladder or bowels)
trauma
pain refractory to medicines
Age <20 or >50
Prolonged corticosteroid drug use
Presence of contusion of abrasions over the spine
What more serious cause of back pain does IV drug use or immunocompromised states put you at risk of?
Osteomyelitis
If, in a patient presenting with back pain, you were concerned about the possibility of malignancy or infection what lab tests would you run?
FBC
Erythrocyte sedimentation rate
C-recative protein
Blood cultures
A patient should receive an X-Ray If symptoms of low back pain continue after how many weeks of conservative treatment?
6-8 weeks
How long is the spinal cord?
42-45cm
What is pain?
An unpleasant sensory and emotional experience associated with actual or potential tissue damage
What catabolic stress responses are associated with pain?
Anxiety, depression, sleep impairment, increased blood pressure and heart rate, nausea, vomiting, ileum, urinary retention, uterine inhibition, restlessness, immobility, hyperventilation and cough inhibition
How does pain affect the hormones cortisone, glucagon and growth hormone?
Pain increases these hormones
How does pain affect the hormones insulin and testosterone?
Pain decreases these hormones
Through what type of fibres is physiological painful stimulation transmitted?
A-delta fibres
Through what type of fibres is pathological painful stimulation transmitted?
C fibres
C fibres transmit information faster than A-delta fibres. T/F?
False - the opposite is true
Physiological pain can be described as sharp, short and localised. How is pathological pain described?
Dull, diffuse, prolonged, produces spasm and guarding
Pathological pain can be abolished by morphine. Can physiological pain be abolished by morphine?
No
To which laminae of the spinal cord to the primary afferent transmit sensory painful stimuli?
Laminae 1+2
What neurotransmitters are used by excitatory interneurons?
Glutamate
What neurotransmitters are used by inhibitory interneurons?
GABA and glycine
What is the name of the theory behind transcutaneous electrical nerve stimulation (TENS)?
Gate control theory of pain
What is allodynia?
Pain from a stimulus which is not normally painful
What substances can activate nociceptors?
Potassium ions 5HT Bradykinin Hydrogen ions Histamine ATP Adenosine
Describe the process of peripheral sensitisation?
Substances such as bradykinin, cytokines, substance P and histamine act to lower the threshold at which nociceptors activate. This process of lowering painful stimuli threshold continues after the initial inflammatory stimulus has ended
Describe the process of central sensitisation?
Mediated by the decreased release of GABA and glycine from interneurons and the decreased released fo NA and 5HT
How long does general pain have to last for it to be considered chronic?
3 months
What is the difference between nociceptive and neuropathic pain?
Nociceptive pain is due to tissue damage
Neuropathic pain is due to nerve damage
Nociceptive pain from somatic sites is well localised dermatomal, shape, aching, gnawing and constant with no associations. How can nociceptive pain from visceral sites be described?
Vague distribution Diffuse to body surface Dull Cramp Dragging Often periodic Often associated with nausea, sweating, tachycardia and hypertension
How might a patient describe the sensation of neuropathic pain?
Shooting Electric-Shock like burning tingling numbness
Give examples of some causes of neuropathic pain
Post-stroke Lumbar radicular diabetic peripheral neuropathy post-hepatic neuralgia chronic post-surgical pain
Give examples of causes of low back pain
Disc bulge or rupture osteoarthritis lumbar instability joint degeneration problems with surrounding muscles and ligaments
Describe how a disc herniation could cause both neuropathic and nociceptive pain?
Leakage of substances from nucleus pulpous can active the peripheral nociceptors to cause nociceptive pain
compression and inflammation fo the nerve root can cause neuropathic pain
Low back pain may cause radicular pain which travels into the lower limb along a narrow band. How is this pain provoked?
Straight leg raise
What factors need to be assessed when covering a history of a patient presenting with pain?
Site, radiation, quality, severity, duration, frequency, relieving factors and associated phenomena
impact on quality of life
patient’s knowledge and expectations
relationship between pain and functional impairment
This is an inter-relationship between pain, sleep and anxiety/depression. T/F?
True
Patients with neuropathic pain commonly experience significant co-morbid symptoms, such as…?
Poor apetitie Anxiety depression difficulty concentrating drowsiness lack of energy difficulty speaking
What drugs are prescribed in step 1 of the WHO analgesic ladder?
Paracetamol and NSAIDs
What drugs are prescribed in step 2 of the WHO analgesic ladder?
codeine
dihydrocodeine
What drugs are prescribed in step 3 of the WHO analgesic ladder?
morphine oxycodone dental buprenorphine methadone diamorphine pethidine
What drug is prescribed between steps 2 and 3 of the WHO analgesic ladder?
tramadol
10% of Caucasian do not have the required enzyme to metabolise codeine. What enzyme is this?
cytochrome p450 CYP 2D6
Besides the drugs in the WHO analgesic ladder, what other neuropathic analgesics can be used?
Amitriptyline gabapentin pregabalin lidocaine ketamine capsaicin clonidine cannabinoids
What physical therapies are used to treat low back pain?
Maintaining activity
physiotherapy
TENS
How can acute pain be prevented from becoming chronic pain?
Early mobilisation
Limiting time of pain
Psychological input
What psychological input is used in the management of low back pain?
clinician explanation of pain education classes support groups pain management programs 1:1 psychology
In neuropathic pain, which additional type of fibre is used to transmit pain signals?
A-beta fibres
Which substances stimulate pain following tissue damage?
Potassium ions
Prostaglandins
Once pain has been stimulated, nerve fibres also back propagate to stimulate the release of CGRP and substance P. What is the action of these substances?
CGRP cause dilation of blood vessels
Substance P causes plasma extravasation, oedema and release of bradykinin
In the spinothalamic tract, branches are given off in the spinal lemniscus which activate descending pathways to modulate nociceptive input. What substances are released in order to do this?
5-HT and noradrenaline
In the gate control theory of pain, somatosensory input can override painful stimuli. The bifurcation of the afferent neuron in the dorsal column tract activates inhibitory neurons. T/F?
True
