Muscle atrophy [Muscle wasting]
Muscle atrophy results from denervation or prolonged muscle disuse. When deprived of regular exercise, muscle fibers lose both 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 530 and 531.) 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 any 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.
Medical causes
Amyotrophic lateral sclerosis
Initial symptoms of this progressive disease 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 deep tendon reflexes, 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.
Compartment syndrome and Volkmann’s ischemic contracture
With this acute disorder, muscle atrophy is a late sign of irreversible ischemia, along with contractures, paralysis, and loss of pulses. Earlier signs and symptoms include severe pain that increases with passive muscle movement, along with weakness and paresthesia.
Herniated disk
Here, pressure on nerve roots leads to muscle weakness, disuse, and ultimately, atrophy. The primary symptom is severe lower back pain, possibly radiating to the buttocks, legs, and feet and commonly accompanied by muscle spasms. Diminished reflexes and sensory changes may also occur.
Hypercortisolism
This disorder may cause limb weakness and eventually atrophy. Related cushingoid features include buffalo hump, moon face, truncal obesity, purple striae, thin skin, acne, easy bruising, poor wound healing, elevated blood pressure, fatigue, hyperpigmentation, and diaphoresis. The male patient may be impotent; the female patient may develop hirsutism and menstrual irregularities.
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 this traumatic disorder.
Multiple sclerosis
This degenerative disease 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 deep tendon reflexes, sensory loss or paresthesia, dysarthria, dysphagia, incoordination, ataxic gait, intention tremors, emotional lability, impotence, and urinary dysfunction.
Osteoarthritis
This chronic disorder 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 this disorder, 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 nerve trauma
Injury to or prolonged pressure on a peripheral nerve leads to muscle weakness and atrophy. Associated findings include paresthesia or sensory loss, pain, and loss of reflexes supplied by the damaged nerve. Paralysis may also occur.
Peripheral neuropathy
With this disorder, muscle weakness progresses slowly to flaccid paralysis and eventually atrophy. Distal extremity muscles are generally affected first. Associated findings include 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 deep tendon reflexes.
Protein deficiency
If chronic, this may lead to muscle weakness and atrophy. Other findings include chronic fatigue, apathy, anorexia, dry skin, peripheral edema, and dull, sparse, dry hair.
Radiculopathy
Damaged spinal nerve roots can cause muscle atrophy as well as weakness, paralysis, severe pain and, at times, loss of feeling in the areas supplied by the affected nerves.
Rheumatoid arthritis
Muscle atrophy occurs in the late stages of this disorder, as joint pain and stiffness decrease range of motion and discourage muscle use.
Shy-Drager syndrome
This rare, progressive neurologic syndrome is characterized by muscle atrophy, orthostatic hypotension, incontinence, tremor, rigidity, incoordination, and ataxia. It’s most common in young and middle-aged adults.
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 deep tendon reflexes, positive Babinski’s reflex, sexual dysfunction, priapism, hypotension, and anhidrosis (usually unilateral).
Stroke
Stroke may produce contralateral or bilateral weakness and eventually atrophy of the arms, legs, face, and tongue. Associated signs and symptoms depend on the site and extent of vascular damage and may include dysarthria, aphasia, ataxia, apraxia, agnosia, and ipsilateral paresthesia or sensory loss. The patient may develop visual disturbance, altered level of consciousness, amnesia and poor judgment, personality changes, and emotional lability. He may also report bowel and bladder dysfunction, vomiting, headache, and seizures.
Thyrotoxicosis
This disorder may produce insidious, generalized muscle weakness and atrophy. Related findings include extreme anxiety, fatigue, heat intolerance, diaphoresis, tremors, tachycardia, palpitations, ventricular or atrial gallop, dyspnea, weight loss, and an enlarged thyroid. Exophthalmos may be present.
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.
Special considerations
Because contractures can occur as atrophied muscle fibers shorten, help the patient maintain muscle length by encouraging him to perform frequent, active range-of-motion 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, use heat, pain medication, or relaxation techniques to relax the muscle. Then slowly stretch it to full extension. (Caution: Don’t pull or strain the muscle; you may tear muscle fibers and cause further contracture.) If these techniques fail to correct the contracture, use moist heat, a whirlpool bath, resistive exercises, or ultrasound therapy. If these techniques aren’t effective, surgical release of contractures may be necessary.
Teach the patient to use necessary assistive devices properly to ensure his safety and prevent falls. Have the patient consult a physical therapist for a specialized therapy regimen.
Prepare the patient for electromyography, nerve conduction studies, muscle biopsy, and X-rays or computed tomography scans.
Pediatric pointers
In young children, profound muscle weakness and atrophy can result from muscular dystrophy. Muscle atrophy may also result from cerebral palsy and poliomyelitis, and from paralysis associated with meningocele and myelomeningocele.
Pictures
![Muscle atrophy [Muscle wasting] - 2641.png](/bookimages/8/2641.png)
Book Source Details
- Book Title: Professional Guide to Signs & Symptoms (Fifth Edition)
- Author(s): Springhouse
- Year of Publication: 2006
- Copyright Details: Professional Guide to Signs & Symptoms (Fifth Edition), Copyright © 2006 Lippincott Williams & Wilkins.
Other Book Chapters Related to Myopathy
Read excerpts from these other book chapters related to Myopathy:
Medical Books Excerpts
- Muscle spasms
- "Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series" (2007)
- [ read ]
Copyright Details: Professional Guide to Signs & Symptoms (Fifth Edition), Copyright © 2008 Williams & Wilkins.
More About Causes of Myopathy
» Next page: Muscle Cramps (Field Guide to Bedside Diagnosis)
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