Case 23- Physiology Flashcards
What is pain
- Stimulus- Nociception, projections to the higher centres in the brain allow integrated, abstract representation of pain
- Protective- immediate pain warns of imminent tissue damage. Persistent pain- encourages immobilisation of injured area, allowing damaged tissue time to heal
- Psychological/emotional/social- Dictates our experience and reaction to the noxious stimuli
The pain pathway
- Somatosensory system- information on physical stimuli goes from the periphery to the brain. Records touch, temperature, vibration, proprioception and pain
- 1st order neurones- Primary afferent fibres, Dorsal horn of the spinal cord
- 2nd order neurone- Crosses midline at entry to the spinal level. Spinothalamic tracts (contralateral)
- 3rd order neurones- goes from the Thalamus to the Midbrain/Cortex
Pain in the brain
- 3rd order neurones go from the Thalamus to the Midbrain and the Cortx
- Midbrain structure- Limbic system, important for emotion, behaviour and memory
- Cortex- Sensory Homunculus
Acute vs chronic pain
- Acute- <12 week duration from onset. Defined start and end point. Usually related to injury or disease
- Chronic- continuous, long term pain >12 weeks in duration. Pain that continues after the expected healing time
Types of pain
- Nociceptive (60%)
- Neuropathic (15%)
- Combination (25%)
Risk factors associated with pain
- Female sex
- Age
- Physical or sedentary occupation
- Lack of social network support
- Socioeconomic support
Factors influencing perception of pain
- Emotion- Stressed, Angry, Bored, Lonely
* Physical conditions- Tired, Hungry, Cold
Meaning of pain
- Cancer patients attributing pain to disease progression
* Extrapolate to their own personal prognosis / survival timelines
Religious / Cultural background- Pain
• Pain as moral or spiritual atonement – positive perceptions
• Pain as punishment for sins - negative perceptions
Sense of control over pain- Lack of knowledge / helplessness can lead to poor pain control
Pain and mental health
- Depression- correlation between pain and depressive symptoms
- Anxiety- higher incidence of anxiety disorders in patients with chronic pain. Patients develop fear of pain and are hyper-vigilant to painful stimuli so may avoid activities
Assessment of pain
- Assessment is important for diagnosis of underlying cause, this facilitates selection of appropriate treatment. Allows modification of treatment depending on patients response
- Component of pain assessment- History (SOCRATES), Physical examination (Vital signs, General observations, facial signs), Pain measurement
Assessment of pain
- Assessment is important for diagnosis of underlying cause, this facilitates selection of appropriate treatment. Allows modification of treatment depending on patients response
- Component of pain assessment- History (SOCRATES), Physical examination (Vital signs, General observations, facial signs), Pain measurement
Measurement of pain- pain is divided into 3 dimensions
- Sensory, discriminative= Sensory aspect of pain, described in intensity, location and temporal aspects
- Affective, motivational- emotional and suffering aspects of pain
- Cognitive, evaluative- how pain is interpreted by the patient, resultant impact on patients function and quality of life
Pain measurement tools
- Unidimensional- measures single dimension i.e. intensity of pain, most commonly found when assessing acute pain
- Multidimensional- assessment across multiple dimensions, becomes more useful in long term pain
Unidimensional tools for assessing pain
- Categorical scales i.e. verbal descriptive scale (none, mild, moderate, severe). Simple, quick, easy to use. Limited descriptors so is less specific
- Visual analogue scale- avoids descriptors, requires cognition, no language barrier
Examples of unidimensional tools for assessing pain
- Numerical rating scales= Often used verbally ‘1-10.’ Validated, easy, quick, cognitively challenging
- Picture scales/pain drawings= simple, easy. Used in children and people with learning difficulties or those with poor language skills.
Multidimensional tools for assessing pain- brief pain inventory
- Validated. Originally for Cancer patients, since adapted for non Cancer patients
- 17 item, self rating scale, includes demographic data, medication use, sensory & reactive components to pain
Multidimensional tools for assessing pain- McGill pain Questionair
- Uses multidimensional scales looking at; Sensory, Affective, Cognitive experiences of the pain
- Validated. 16 languages available
- Lengthy (15 mins) requires good language skills
Multidimensional tools for assessing pain- Short Form McGill Pain Questionaire
- Shortened version of MPQ
- 2-3 minutes to complete
- 15 descriptors covered, 11 sensory, 4 affective
Multidimensional tool for assessing pain- Hospital anxiety and Depression scale
- Screening tool for presence & severity of Anxiety / Depression
- Validated for hospital, community & primary care settings
- Does not assess pain
Pain management
- Pharmacological therapies
- Regional analgesia
- Physical therapies
- Psychological based therapies
Stepwise approach to pain management
- Mild pain Step 1= Non opioid Analgesics: Aspirin, Paracetamol, NSAIDS with or without Adjuvants
- Moderate pain Step 2= Weak opioid Analgesics= Tramadol, Codeine, with or without Non opioids and Adjuvants
- Sever pain Step 3= Strong opioid Analgesics= Morphine, Fentanyl, Buprenorphine, Methadone. With or without Non-opioids and adjuvants
Regional analgesia
- Plane blocks= Fascia Iliaca block, good for a fractured NOF
- Specific nerve blocks= Femoral nerve for post operative pain
Physical therapies- Pain
Splints, ice packs
Physical therapies- TENS
• Transcutaneous electrical nerve stimulation
• Non-invasive, Easy to use
• Works because of the Gate controlled theory of pain
• Good for: Post-op pain, Labour, Orofacial pain, Angina, Dysmenorrhoea
• Contraindications/Cautions- Pacemakers (may malfunction), Uterus (stimulates contractions), Neck position (Laryngospasm, bradycardias via vagal stimulation), Spinal cord stimulators (Reprogramming)
Gate controlled theory of pain
- Concept of a ‘spinal’ gate
- Small fibres carrying nociceptive stimuli
- Large fibres alternate stimuli (vibration, temperature)
- Interneurone blocked at synapse
- Transmission to ascending spinal pathways blocked
Physical therapies- Temperature
- Cooling- sports injuries. Good for spastic muscles after intense exercise. Diminishes reflex activity in muscles allowing for therapeutic effect. Lasts for hours once muscles cooled
- Heat treatment- increased blood flow and decreased muscle spasm. Counterirritant effect which works on the principles of the Gate theory, there is a reduction of oedema. Can cause caution burns
Physical therapy- short wave diathermy
- Low intensity lasers
* Good for osteoarthritic joints and muscular sprains
Psychological based therapies
- Used as adjuncts to pharmacological/physical therapies
- Proven physiological benefits- decreased stimulation of the sympathetic system, muscle relaxation, decreased heart rate, improved oxygenation, low blood pressure
Examples of Psychological based therapies for pain
- Cognitive behavioural therapy (CBT)- improves patient understanding/changes perception of pain. Promotes active perception in assessment/control of pain
- Biobehavioural- procedures focused on teaching self control/modify behavioural patterns
- Mind-body – interventions that stress cognitive/psychological and physical interactions involved with patients pain assessment/control
Acute/chronic pain psychological techniques
- Relaxation
- Distraction- focus attention/concentration elsewhere and away from the pain
- Imagery- use of imagination to create mental picture using all 5 senses
- Biofeedback- measurement of neuromuscular / Autonomic activity. Then relayed to the patient to awareness and psychological control
- Hypnosis
Pain- patient information and education
- Patients report less pain
- Fewer analgesic requirements
- Ideally education delivered before pain experienced
- Often very helpful during painful procedures
- Very effective for obstetrics
Other beneficial therapies for pan management
- Urinary catheterisation for retention
- Use of warming blankets
- Reassurance
- Music
- Virtual Reality
Factors which lead to autoimmune disease
Breakdown of tolerance Genetics Sex hormones Mutations in immune components HLA allele Aging Treg cells Environmental factors Infections Drugs Tissue injury
Myasthenia Gravis
What is it- Muscle weakness (Organ-specific disease affecting neuromuscular junctions)
Commonly affects- Females 20-40 and Males aged 60-80
Genes- HLA-DR3
Extrinsic risk factors- smoking, obesity and viral infections i.e. polio
Myasthenia gravis symptoms
Drooping eyelids, Double vision, Slurred speech, Difficulty chewing & swallowing and Difficulty making facial expressions
Myasthenia gravis mechanism of action
- Autoantibodies bind to α chain of nicotinic acetylcholine receptor on skeletal muscle cells at neuromuscular junctions
- No receptor activation
- Receptors internalized and degraded
- Neuromuscular transmission blocked
Lupus (SLE)
What is it- Chronic inflammation of the joints, skin and organs (systemic disease)
Commonly affects- females aged 20-40 (most common in black and asian women)
Genetics- HLA-DR2 & HLA-DR3 and genetic complement deficiency
Extrinsic risk factors- Smoking, UV light exposure, drugs i.e. hydralazine, oestrogen and viral infections i.e. EBV and COVID-19
Symptoms of Lupus (SLE)
Butterfly rash on the face, appetite loss, hair loss, fever, fatigue, photosensitivity, mouth ulcers, painful and swollen joints & Raynauds phenomenon
Lupus (SLE)- mechanism of action
- Chronic production of IgG Ab directed at ubiquitous self antigens e.g. dsDNA
- Autoantigens are released from dead/dying cells due to tissue injury
- Continuous small immune complex formation
- Deposition of immune complexes
- Phagocytic cells activated through Fc receptor
- Inflammation due to overproduction and/or defective clearance of immune complexes leading to further tissue damage
Rheumatoid arthritis
What is it- chronic systemic disease that causes inflammation and progressive joint destruction
Commonly affects- females aged 30-55
Genetics= HLA-DR4 and HLA-DR1
Extrinsic risk factors- smoking and oestrogen
Symptoms of rheumatoid arthritis
Joint pain, swelling and stiffness, often with tiredness, decreased energy, high temperature and weight loss
Rheumatoid arthritis mechanism of action
- Initial trigger causes inflammation attracting WBCs into tissue
- CD4 T cells activate macrophages causing cytokine release and further inflammation
- Cytokines induce fibroblasts to produce MMPs and RANK ligands
- MMPs attack tissue and RANK ligands activate osteoclasts resulting in joint destruction
- B cells also activated producing rheumatoid factor leading to immune complex formation and an amplified inflammatory response
Rheumatoid arthritis pathology
1) Genetic and extrinsic susceptibility
2) Inflammatory synovitis
3) Activated CD4+ T cell causes TNF to be released resuliting in bone erosion and osteoclast activation
4) The activated CD4+ T cell causes activation of B cells. In 75% this produces rheumatoid factor (IgM anti-IgG Ans)
5) The IgG-IgM complexes activate complement and amplify inflammatory responses
Proximal humerus fracture
Older osteoporotic patient-fall onto an outstretched arm.
Younger patients-high impact trauma.
Sling immobilisation or surgery
Anterior dislocation of the shoulder
95% of dislocations
The humeral head is located underneath the coracoid proccess
In the lateral view- the humeral head is no longer in the centre of the Y
Posterior dislocation of the shoulder
Humeral head becomes more rounded-’light bulb sign’
There is no overlap between the glenoid and the humeral head
Less common than anterior dislocation
Most often in the elderly, post-seizure and electrocution
The growth plates of the proximal humerus fuse at around 16 years.
Clavicle fracture
Mostly occur in the middle third segment
FOOSH or direct trauma
Sling immobilisation or surgery
Clavicle fracture
Mostly occur in the middle third segment
FOOSH or direct trauma
Sling immobilisation or surgery
Distal fracture humerus
Fracture through the lateral epicondyle of the humerus
High energy injury- sport or RTC
Older adults- osteoporosis
Cast immobilisation or surgery
Radial head fracture
Fall onto outstretched hand
Management: Conservative (sling), ORIF
Posterior elbow dislocation
Can also have an associated fracture
Management: Closed reduction and splinting, ORIF with ligament repair
Wrist= Colles’ fracture
Fractured distal radius with dorsal impaction 'Dinner fork' deformity Typically caused by FOOSH Undisplaced > cast alone Mild displacement > closed reduction Significant deformity > ORIF
Wrist= Colles’ fracture
Fractured distal radius with dorsal impaction 'Dinner fork' deformity Typically caused by FOOSH Undisplaced > cast alone Mild displacement > closed reduction Significant deformity > ORIF
Wrist= Smith’s fracture
Fractured distal radius with volar (palmar) displacement
Direct blow to dorsal forearm or fall on flexed hand
Depending on impact, there may be one or several fragments
Non-displaced > cast
Mild displacement > closed reduction
Significant deformity/displacement > ORIF
Wrist- Barton’s fracture
Intra-articular fracture of distal radius with radiocarpal dislocation
Fracture line extends into distal articular surface via the volar aspect
Fall on extended pronated forearm
Intra-articular component distinguishes it from Colles’ or Smith’s
It generally requires ORIF with plates and screws
Ulna Styloid fracture
Can cause instability at the distal radio-ulnar joint
Seldom require fixation, even when in conjunction with a distal radius fracture
Exception is when there is instability or significant deformity
Wrist- Scaphoid fracture
Scaphoid fracture (waist) Mechanism: Fall on outstretched hand Tenderness over the anatomical snuffbox suggests a scaphoid fracture. Beware of avascular necrosis-if a# cannot be seen on x-ray then immobilise the thumb and ask the patient to return for follow up.
