MUSCULAR ATROPHY

MUSCULAR ATROPHY: Excerpt from Differential Diagnosis in Primary Care

This symptom is developed using both anatomy and physiology. Atrophy of any muscle may develop in seven ways.

1. Lack of use of the muscle
2. Malnutrition or increased body metabolism
3. Primary muscle disease
4. Myoneural junction disease
5. Peripheral nerve disease
6. Nerve root disease
7. Spinal cord disease

When recalling the differential diagnosis of muscular atrophy, think of these seven factors and the causes will unfold.

1. Lack of use of the muscle. In focal or generalized bone or joint disease there is diminished use of the extremity or part involved, so the muscles atrophy. “Disuse” atrophy may also occur in compensation neurosis, hysteria, depression, and in many central nervous system diseases in which motivation is gone.
2. Malnutrition or body hypermetabolism. Starvation causes diffuse muscular wasting. Diffuse muscular wasting also occurs in anything that speeds up body metabolism, including hyperthyroidism, metastatic carcinoma and other diffuse neoplasms, chronic inflammatory conditions such as rheumatoid arthritis (RA) and collagen disease, and chronic fever of any cause.
3. Primary muscle disease. Muscular dystrophy, dermatomyositis, trichinosis, and McArdle syndrome should be considered here.
4. Myoneural junction. This category makes one think of myasthenia gravis.
5. Peripheral nerve disease. Diabetic neuropathy and the neuropathy from lead, arsenic, and other toxins should be considered here. Periarteritis nodosa and trauma to the nerve may give an asymmetric neuritis. Hereditary neuropathies such as Charcot–Marie–Tooth disease and Dejerine–Sottas hereditary hypertrophic neuritis are also considered here. Porphyria is another cause to recall in this category.
6. Nerve root disease. Spinal column disorders that compress the root include fractures, herniated disks, spondylolisthesis, tuberculosis, metastatic tumors, and multiple myelomas.
7. Spinal cord disease. The degenerative diseases such as amyotrophic lateral sclerosis, progressive muscular atrophy, and syringomyelia must be considered here. In addition, poliomyelitis, transverse myelitis of various areas, anterior spinal artery occlusion, infectious polyneuritis, and spinal cord tumors must be recalled.

Approach to the Diagnosis

Focal atrophy of a muscle often means a damaged peripheral nerve or root. If there are visible fasciculations, a lesion of the spinal cord or root is most likely. Electromyography will determine which portion of the nerve is affected. It will also be helpful in diagnosing muscle disease. Muscle biopsy is valuable in ruling out trichinosis, dermatomyositis, or muscular dystrophy. If there are fasciculations, a spine x-ray, spinal tap, and myelography or MRI may be necessary to establish the diagnosis. Sedimentation rate, CRP, RA titer, ANA, and tuberculin tests may be necessary.

Other Useful Tests

1. Serum protein electrophoresis (collagen disease, multiple myeloma)
2. Muscle enzyme tests (muscular dystrophy, dermatomyositis)
3. 24-hour urine creatine and creatinine levels (muscular dystrophy)
4. Acetylcholine receptor antibody titer (myasthenia gravis)
5. Thyroid function tests (hypothyroid myopathy)
6. Glucose tolerance test (diabetic neuropathy)

Pictures

Book Source Details

• Book Title: Differential Diagnosis in Primary Care
• Author(s): R. Douglas Collins MD, FACP
• Year of Publication: 2007
• Copyright Details: Differential Diagnosis in Primary Care, Copyright © 2007 Lippincott Williams & Wilkins.

More About Muscle conditions

• Back to disease: Muscle conditions: Introduction
• Next Book Extract About Muscle conditions: MUSCULAR CRAMPS (Differential Diagnosis in Primary Care)
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.

More About This Book: Title: Differential Diagnosis in Primary Care Authors: R. Douglas Collins MD, FACP Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 0-7817-6812-8

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