Acute motor deficits occur when there is either a sudden loss of connectivity between the CNS and the muscles or there is dysfunction of the muscles themselves. Loss of connection can occur anywhere from the CNS to the motor-end plate. Acute motor deficits occur in a wide range of disease states. Careful questioning of a patient who reports sudden motor loss can help determine the exact anatomy of the motor deficit, any accompanying features, and the likely pathophysiology. The anatomic description of the deficit helps localize the site of dysfunction. This may include the brain, spinal cord, peripheral nerves, and muscles. Motor deficits can be intermittent, relapsing, or acute and catastrophic, although these features do not always help define the pathophysiology.
Once the probable site of dysfunction has been identified, consideration can be given to the likely type of process involved (vascular, trauma, infection, autoimmune/inflammatory, metabolic, compression, or other). Although a general knowledge of the different systemic pathologies is helpful, there can be considerable overlap in presentations. For example, a sudden loss of motor function might often appear to have a vascular cause, but other conditions such as edema related to a tumor in the white matter, or chronic subdural hematoma can present with a similar history, albeit less frequently.
- Subdural hematoma
- Subarachnoid hemorrhage (SAH)
- Thoracolumbar spine trauma
- Cervical spine trauma
- Brain abscess
- West Nile virus (WNV)
- Guillain-Barre syndrome (GBS)
- Myasthenia gravis (MG)
- Transverse myelitis (TM)
- Idiopathic inflammatory myopathy
- Acute hypokalemia
- Acute intermittent porphyria (AIP)
- Periodic paralysis
- Amyotrophic lateral syndrome
- Muscular dystrophies
- Common hereditary lysosomal storage diseases
- Type 1 glycogen storage disease (GSD I)
- Drug-induced myopathies
- Drug-induced neuropathy
- Toxin-induced dysfunction
- Compartment syndrome
- Brain tumor
- Spinal cord compression
- Bell palsy
Clinical Associate Professor PM&R
Wayne State University School of Medicine
KFC declares that he has no competing interests.
Assistant Professor of Neurosciences
Hotchkiss Brain Institute
University of Calgary
CT declares that he has no competing interests.
Department of Neurological Sciences
Institute of Neurology C. Mondino
SR declares that she has no competing interests.
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