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ULY CLINIC

12 Septemba 2025, 01:22:48

Muscle Atrophy (Muscle Wasting)

Muscle atrophy refers to the loss of muscle bulk, strength, and length, usually resulting from denervation, prolonged disuse, metabolic or endocrine disorders, or aging. Atrophy produces visible muscle wasting, contour changes, and functional weakness, even if mild.

History and Physical Examination

History

Ask onset, location, and progression of muscle wasting.
Inquire about associated symptoms: weakness, pain, sensory loss, recent weight changes.
Review medical history: chronic illness, musculoskeletal/neurologic disorders, trauma, endocrine/metabolic disease.
Ask about alcohol or drug use, especially steroids.

Physical examination

Identify location and extent of atrophy visually.
Examine all major muscle groups for size, tone, and strength.
Measure limb circumference, comparing sides; use consistent reference points with the limb fully extended.
Assess for contractures by extending joints and noting resistance/pain.
Palpate peripheral pulses, assess sensory function, and test deep tendon reflexes (DTRs).

Examination Tip

Measuring Limb Circumference:Mark a consistent reference point each time for accurate, reproducible measurements.

Medical causes

Condition	Murmur Characteristics / Muscle Findings	Associated Findings
Amyotrophic lateral sclerosis (ALS)	Progressive weakness and atrophy, beginning in one hand/arm	Fasciculations, hyperactive DTRs, leg spasticity, dysphagia, dysarthria, drooling, respiratory insufficiency, depression
Burns	Atrophy due to fibrous scar tissue, pain, loss of serum proteins	Limited movement
Hypothyroidism	Reversible proximal limb muscle weakness/atrophy	Cramps, stiffness, cold intolerance, weight gain, dry skin, puffy face/hands/feet, bradycardia
Meniscal tear	Quadriceps atrophy from prolonged knee immobility	Knee pain, limited ROM
Multiple sclerosis	Arm/leg atrophy from chronic weakness	Spasticity, contractures, diplopia, nystagmus, dysarthria, ataxia, tremors, sensory loss, urinary dysfunction
Osteoarthritis	Proximal atrophy from joint disuse	Bony deformities, Heberden’s/Bouchard’s nodes, crepitus, contractures
Parkinson’s disease	Muscle rigidity and disuse atrophy	Resting tremor, bradykinesia, propulsive gait, masklike facies, drooling, dysphagia, dysarthria
Peripheral neuropathy	Distal muscle weakness progressing to atrophy	Loss of vibration, paresthesia, pain, anhidrosis, diminished DTRs
Protein deficiency	Chronic muscle weakness and wasting	Fatigue, apathy, anorexia, dry skin, peripheral edema, sparse hair
Rheumatoid arthritis	Late-stage atrophy due to reduced ROM	Joint pain, stiffness
Spinal cord injury	Flaccid → spastic paralysis leading to atrophy	Level-dependent sensory/motor loss, bowel/bladder dysfunction, hypotension, sexual dysfunction

Other causes

Drugs: Long-term steroid therapy affects muscle metabolism, especially in limbs.
Immobility: Bed rest, casts, splints, or traction can cause disuse atrophy.

Special considerations

Prevent contractures with frequent active, active-assisted, or passive ROM exercises.
Use splints or braces to maintain muscle length.
Apply heat, analgesics, or relaxation techniques before stretching if resistance is present.
If conservative measures fail, surgical release may be needed.
Ensure safety with assistive devices and refer to a physical therapist for specialized regimens.
Prepare for diagnostic tests: EMG, nerve conduction studies, muscle biopsy, X-rays, or CT scans.

Patient counseling

Educate on assistive device use, exercise regimens, and fall prevention.
Emphasize the importance of maintaining muscle strength and mobility.

Pediatric pointers

In children, profound muscle weakness/atrophy may result from:
- Muscular dystrophy
- Cerebral palsy
- Poliomyelitis
- Paralysis from meningocele or myelomeningocele

References

Belavý DL, Ng JK, Wilson SJ, Armbrecht G, Stegeman DF, Rittweger J, Richardson CA. Influence of prolonged bed-rest on spectral and temporal electromyographic motor control characteristics of the superficial lumbo-pelvic musculature. J Electromyogr Kinesiol. 2009;20:170–179.
Claus AP, Hides JA, Moseley GL, Hodges PW. Different ways to balance the spine: Subtle changes in sagittal spinal curves affect regional muscle activity. Spine. 2009;34:208–214.