MONOPLEGIA
MONOPLEGIA: Excerpt from Differential Diagnosis in Primary Care
Monoplegia is the paralysis of one extremity. Following the nerve
impulse from the cerebral cortex down through the spinal cord, nerve roots,
brachial and lumbosacral plexus, peripheral nerve, myoneural junction, and
muscles allows us to recall the most significant causes of monoplegia.
Cerebral cortex. Monoplegia may result from a
parasagittal tumor or abscess and anterior cerebral artery embolism or
thrombosis. Occasionally an occlusion of the middle cerebral artery or its
branches may cause monoplegia of the upper extremity, but there are almost
always neurologic signs in the lower extremities in these cases.
Spinal cord. Early space-occupying lesions of the
spinal cord and amyotrophic lateral sclerosis may present with monoplegia.
It is unlikely for multiple sclerosis or transverse myelitis to present this
way.
Nerve roots. Poliomyelitis, progressive muscular
atrophy, and herniated discs may present with monoplegia. Early cauda equina
tumors may present with monoplegia as well.
Brachial plexus. This would bring to mind
brachial plexus neuropathy, thoracic outlet syndrome, and Pancoast tumors.
Sciatic plexus. This would suggest sciatic
neuritis or injury.
Peripheral nerve. Trauma or entrapment of the
peripheral nerves may present as a monoplegia. Charcot-Marie tooth disease
may begin in one extremity.
Myoneural junction. Myasthenia gravis or
Eaton-Lambert syndrome may occasionally present as weakness in one
extremity.
Muscle. It is unusual for the various forms of
muscular dystrophy and dermatomyositis to present with monoplegia.
Approach to the Diagnosis
The neurologic examination will help determine the site of the lesion
and thus the likely etiology. If there are hyperactive reflexes in the
involved extremity, the lesion is probably in the upper spinal cord or
cerebral cortex. If there is associated facial palsy or other cranial nerve
signs, the lesion is probably in the brain or brainstem.
Hypoactive reflexes in the involved extremity indicate a lesion in the nerve
roots, nerve plexus, or peripheral nerves. However, acute cerebral
thrombosis, hemorrhage, or embolism may present with hypoactive reflexes in
the involved extremity. Before proceeding with an expensive workup, a
neurologist needs to be consulted.
Monoplegia of the upper extremities with hyperactive reflexes would indicate
the need for an MRI or CT scan of the brain or cervical spinal cord.
Monoplegia of the lower extremities with hyperactive reflexes would suggest
the need for an MRI of the thoracic spine. However, a CT scan or MRI of the
brain may still be required to rule out a parasagittal lesion.
Monoplegia with hypoactive reflexes may require an MRI or CT scan of the
spine, electromyogram (EMG), and nerve conduction velocity (NCV) studies.
Blood lead levels, glucose tolerance tests, and other studies indicated in a
neuropathy workup (page 345) may be
required. Muscle biopsy and acetylcholine receptor antibody titers may be
necessary.
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 Brown-Sequard Syndrome
More Medical Textbooks Online about Brown-Sequard Syndrome
Review other book chapters online related to Brown-Sequard Syndrome:
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- MONOPLEGIA
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- "Algorithmic Diagnosis of Symptoms and Signs" (2003)
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- Analgesia
- "Handbook of Signs & Symptoms (Third Edition)" (2006)
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- Analgesia
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- Analgesia
- "Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series" (2007)
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
» Next page: SPASTICITY (Differential Diagnosis in Primary Care)
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