Muscle atrophy [Muscle wasting]
Muscle atrophy results from denervation or prolonged muscle disuse. When deprived of regular exercise, muscle fibers lose bulk and length, producing a visible loss of muscle size and contour and apparent emaciation or deformity in the affected area. Even slight atrophy usually causes some loss of motion or power.
Atrophy usually results from neuromuscular disease or injury. However, it may also stem from certain metabolic and endocrine disorders and prolonged immobility. Some muscle atrophy also occurs with aging.
History and physical examination
Ask the patient when and where he first noticed the muscle wasting and how it has progressed. Also ask about associated signs and symptoms, such as weakness, pain, loss of sensation, and recent weight loss. Review the patient's medical history for chronic illnesses; musculoskeletal or neurologic disorders, including trauma; and endocrine and metabolic disorders. Ask about his use of alcohol and drugs, particularly steroids.
Begin the physical examination by determining the location and extent of atrophy. Visually evaluate small and large muscles. Check all major muscle groups for size, tonicity, and strength. (See Testing muscle strength, pages 410 and 411.) Measure the circumference of all limbs, comparing sides. (See Measuring limb circumference.) Check for muscle contractures in all limbs by fully extending joints and noting pain or resistance. Complete the examination by palpating peripheral pulses for quality and rate, assessing sensory function in and around the atrophied area, and testing deep tendon reflexes (DTRs).
Medical causes
Amyotrophic lateral sclerosis (ALS).Initial symptoms of ALS include muscle weakness and atrophy that typically begin in one hand, spread to the arm, and then develop in the other hand and arm. Eventually, weakness and atrophy spread to the trunk, neck, tongue, larynx, pharynx, and legs; progressive respiratory muscle weakness leads to respiratory insufficiency. Other findings include muscle flaccidity, fasciculations, hyperactive DTRs, slight leg muscle spasticity, dysphagia, impaired speech, excessive drooling, and depression.
Burns.Fibrous scar tissue formation, pain, and loss of serum proteins from severe burns can limit muscle movement, resulting in atrophy.
Hypothyroidism.Reversible weakness and atrophy of proximal limb muscles may occur in hypothyroidism. Associated findings commonly include muscle cramps and stiffness; cold intolerance; weight gain despite anorexia; mental dullness; dry, pale, cool, doughy skin; puffy face, hands, and feet; and bradycardia.
Meniscal tear.Quadriceps muscle atrophy, resulting from prolonged knee immobility and muscle weakness, is a classic sign of meniscal tear.
Multiple sclerosis.Multiple sclerosis may produce arm and leg atrophy as a result of chronic progressive weakness; spasticity and contractures may also develop. Associated signs and symptoms typically wax and wane and include diplopia and blurred vision, nystagmus, hyperactive DTRs, sensory loss or paresthesia, dysarthria, dysphagia, incoordination, an ataxic gait, intention tremors, emotional lability, impotence, and urinary dysfunction.
Osteoarthritis.Osteoarthritis eventually causes atrophy proximal to involved joints as a result of progressive weakness and disuse. Other late signs and symptoms include bony joint deformities, such as Heberden's nodes on the distal interphalangeal joints, Bouchard's nodes on the proximal interphalangeal joints, crepitus and fluid accumulation, and contractures.
Parkinson's disease.With Parkinson's disease, muscle rigidity, weakness, and disuse may produce muscle atrophy. The patient may exhibit insidious resting tremors that usually begin in the fingers (pill-rolling tremor), worsen with stress, and ease with purposeful movement and sleep. He may also develop bradykinesia; a characteristic propulsive gait; a high-pitched, monotone voice; masklike facies; drooling; dysphagia; dysarthria; and, occasionally, oculogyric crisis or blepharospasm.
Peripheral neuropathy.With peripheral neuropathy, muscle weakness progresses slowly to flaccid paralysis and eventually atrophy. Distal extremity muscles are generally affected first. Associated findings include a loss of vibration sense; paresthesia, hyperesthesia, or anesthesia in the hands and feet; mild to sharp, burning pain; anhidrosis; glossy red skin; and diminished or absent DTRs.
Protein deficiency.If chronic, protein deficiency may lead to muscle weakness and atrophy. Other findings include chronic fatigue, apathy, anorexia, dry skin, peripheral edema, and dull, sparse, dry hair.
Rheumatoid arthritis.Muscle atrophy occurs in the late stages of rheumatoid arthritis as joint pain and stiffness decrease range of motion (ROM) and discourage muscle use.
Spinal cord injury.Trauma to the spinal cord can produce severe muscle weakness and flaccid, then spastic, paralysis, eventually leading to atrophy. Other signs and symptoms depend on the level of injury, but may include respiratory insufficiency or paralysis, sensory losses, bowel and bladder dysfunction, hyperactive DTRs, a positive Babinski's reflex, sexual dysfunction, priapism, hypotension, and anhidrosis (usually unilateral).
Other causes
Drugs.Prolonged steroid therapy interferes with muscle metabolism and leads to atrophy, most prominently in the limbs.
Immobility.Prolonged immobilization from bed rest, casts, splints, or traction may cause muscle weakness and atrophy.
Nursing considerations
▪ Help the patient maintain muscle length by encouraging him to perform frequent, active ROM exercises.
▪ If he can't actively move a joint, provide active assistive or passive exercises, and apply splints or braces to maintain muscle length.
▪ If you find resistance to full extension during exercise, consult the physical therapist.
▪ Use heat, pain medication, or relaxation techniques to relax resistant muscles.
▪ Prepare the patient for electromyography, nerve conduction studies, muscle biopsy, and X-rays or computed tomography scans.
Patient teaching
▪ Teach the patient to use necessary assistive devices properly to ensure his safety and prevent falls.
▪ Discuss safety measures that that patient should follow.
▪ Teach exercises that the patient can perform at home and increase in intensity as his muscle strength improves.
Pictures
![Muscle atrophy [Muscle wasting] - 5612.1.png](/bookimages/16/5612.1.png)
Book Source Details
- Book Title: Nursing: Interpreting Signs and Symptoms
- Author(s): Springhouse
- Year of Publication: 2007
- Copyright Details: Nursing: Interpreting Signs and Symptoms, Copyright © 2007 Lippincott Williams & Wilkins.
Other Book Chapters Related to Muscle atrophy
Read excerpts from these other book chapters related to Muscle atrophy:
Copyright Details: Nursing: Interpreting Signs and Symptoms, Copyright © 2008 Williams & Wilkins.
More About Causes of Muscle atrophy
» Next page: MUSCULAR ATROPHY (Differential Diagnosis in Primary Care)
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