3. Muscular Pathologies Flashcards
Muscle Shortening
If a muscle is continuously contracted, the actin-myosin filaments remain attached.
• Chronic muscle contracture causes muscle fatigue but also places a strain on the muscles skeletal attachments.
Muscle Strain and Tear
Muscle Strain:
• Over-stretching of muscle fibrils or the tendon, occurring when a joint is forced beyond its normal range(“pulled muscle”).
• The muscle remains whole and blood supply intact to permit healing.
• Hamstring and back overstraining injuries are common.
Muscle Tear:
• More significant, where the muscle tears and is no longer whole! More likely to cause bruising.
•Preventing natural complete healing. Can lead to fibrosis.
Impingement Syndrome
Impingement syndrome describes a shoulder condition in which movements of the shoulder can be painful and limited.
• In impingement syndrome, the rotator cuff tendons
and/or bursa can become inflamed/damaged. This
is most notable when compressing the space that
they are both found within (the sub-acromial space).
• The sub-acromial space is the area between the
humeral head and the acromion.
• The rotator cuff tendons connect the humerus and
scapula. Normally, when moving the shoulder, the
rotator cuff have to maneuver intricately to prevent
impingement.
Impingement Syndrome: Causes
• Overuse & working with the arms raised
overhead.
• More common with increasing age as blood
supply is poor and the tendons degenerate.
• Positional fault –when the head of the humerusdoes not sit perfectly in the socket.
• Bone spurs - can reduce the space available
for the bursa and tendons to move under the
acromion.
• Oddly sized acromion resulting in reduced
space.
Impingement Syndrome: Signs & Symptoms
- Shoulder ache in early stages.
- Pain when abducting the shoulder or rotating (i.e. Reaching into back pocket)
- Painful arc of movement.
- A catching sensation is felt on lowering the arm.
- Weakness and inability to raise the arm may indicate rotator cuff tear.
Impingemnt Syndrome: Treatment
• Cortisone injection, NSAIDs, surgery.
Fibromyalgia
Fibromyalgia is a chronic pain disorder, heavily associated with widespread musculoskeletal pain and fatigue.
• Often accompanied by multiple, unexplained symptoms, anxiety, depression and functional impairment of daily activities.
• Women are 10 times more commonly affected that men, mostly occurring aged 30-50.
• Has a neurophysiologic basis, characterised by abnormalities in pain processing by the central nervous system (CNS).
• A form of“central sensitisation”: pain perception to sensory stimulus that would not normally be painful.
Fibromyalgia: Pain Processing
- Fibromyalgia is associated with ‘central sensitisation’ –a central disturbance in pain processing.
- Normally, sensory input such as light touch & temperature are sent as nerve signals to the brain/spinal cord where it synapses with nerves.
- In fibromyalgia, alterations occur in pain processing in the spinal cord & brain(‘centrally’).
- High levels of substance P are found in synapses, which makes nerves more sensitised to pain.
- Excess postsynaptic nitric oxide production also causes the synapse to amplify pain signals.
Fibromyalgia: Causes & Triggers
- Biological, environmental and possibly genetic factors are thought to contribute:
- Poor mitochondrial functioning –damaged by free radicals.
- Altered stress response (i.e. excess cortisol, adrenal fatigue).
- Post-viral and chronic toxic load e.g. heavy metals, chemicals.
- Poor gut health –dysbiosis, leaky gut syndrome.
- Serotonin & noradrenaline deficiencies –play a role in pain tolerance.
- Sleep dysregulation (fatigue, ↑pain, ↓activity).
Fibromyalgia: Signs & Symptoms
- Widespread (diffuse) musculoskeletal pain.
- Pain that results from gentle pressure.
- Feeling of “swollen joints”, often with no actual swelling.
- Debilitating fatigue & sleep severely disturbed.
- Headaches (‘muscular’ or ‘migraine’ type).
- IBS symptoms, numbness, tingling and weakness.
- Anxiety and depression
Fibromyalgia: Diagnosis
Criteria for diagnosis:excess pain on palpation in at least 11 of 18 predefined anatomical points.
- The patient experiences pain at tender points at a decreased threshold. However:
- Normal Biopsy.
- Normal electrical muscle tests.
- Drug studies show no benefit of NSAIDS but benefits of antidepressants.
- It is also an ‘exclusion diagnosis’.
Fibromyalgia: Treatments
Pain relief
Pain clinics
Anti-depressants
CBT and counselling
Muscular Dystrophy
Muscular dystrophies are a group of inherited muscular diseases that cause muscle degeneration and weakness.
Many types of muscular dystrophies exist.
Muscular dystrophies are characterised by:
Progressive skeletal muscle atrophy.
Death of muscle cells & tissue (final stages).
Defects in muscle proteins.
Myasthenia Gravis
Myasthenia Gravis is an autoimmune disease of the neuromuscular junction, characterised by fluctuating muscle fatigue & weakness.
• Antibodies block acetylcholine receptors on the motor end plate preventing a nerve impulse being sent to muscle fibres. The muscle becomes progressively weaker.
• Most common in women, age 20-50.
• Muscles of face & neck are commonly affected.
Myasthenia Gravis: Signs and Symptoms
- Weakness of ocular muscles; double vision and ptosis (drooping).
- Weakness in facial muscles(expressions) which spreads to the proximal limbs.
- Difficulty with speech, chewing, swallowing.
- Death may result from failure of the respiratory muscles.
- Symptoms worsen throughout the day.
Myasthenia Gravis: Treatment
• Acetylcholinesterase inhibitors, corticosteroids
to reduce effects of the antibodies (side effects! Including osteoporosis, indigestion, nausea, insomnia, mood changes, diabetes)
• Plasma Exchange in severe cases, injections of
normal immunoglobulins from healthy donors.
Duchenne Muscular Dystrophy
• Caused by a single gene defect on the X chromosome, affecting males, whilst females
can be carriers. Affects 1 in 3500 males.
• Usually diagnosed 3-5 years of age.
• Associated with a lack of a protein called ‘dystrophin’ in muscle cells. Dystrophin anchors the cytoskeleton to the extracellular matrix.
• If this protein is missing, when the cell contracts
there is no support and the cell membrane becomes leaky, allowing materials to flood in.
• This results in muscle degeneration and necrosis
Duchenne Muscular Dystrophy: Signs and Symptoms
- Delayed walking.
- Difficulty getting up from sitting or lying position.
- Clumsiness, frequent falls.
- Waddling gait.
- Speech delay.
- Gowers sign. (using hands to push on legs to stand)
Duchenne Muscular Dystrophy: Diagnosis
- Serum creatine kinase(10-100x normal). This is also often raised in carriers.
- Genetic analysis and muscle biopsy.
Duchenne Muscular Dystrophy: Prognosis
- All muscle types affected: skeletal, smooth and cardiac.
- Small amounts of dystrophin also present in nerve cells (IQ is affected).
- Prognosis poor: usually wheelchair support needed by 10 years and ventilation by 20 years.
- Most die in their late twenties, often from pneumonia and cardio-respiratory failure.
- Therapeutic strategies aimed at prolonging independent
