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Ophthalmoparesis
Ophthalmoparesis
is a physical finding in certain neurologic illnesses. It refers to paralysis
of the extraocular muscles which are responsible for eye movements. It
can refer to complete paralysis of the eyes, in which case it is synonymous
with ophthalmoplegia. More usually, it refers to a partial paralysis,
in contrast to the complete paralysis denoted by ophthalmoplegia.
Ophthalmoparesis can involve any or all of the extraocular muscles,
which include the superior recti, inferior recti, medial recti, lateral
recti, inferior oblique and superior oblique muscles. It can also be classified
by the directions of affected movements, e.g. "vertical ophthalmoparesis".
Ophthalmoparesis can result from disorders of various parts of
the eye and nervous system:
- The orbit (anatomy)
of the eye, including mechanical restrictions of eye movement, as in
Graves disease.
- The muscle, as
in progressive external ophthalmoplegia.
- The neuromuscular
junction, as in myasthenia gravis.
- The cranial nerves
or their brainstem nuclei of the oculomotor, trochlear, and abducens.
- White matter tracts
in the brainstem, as in internuclear ophthalmoplegia, an occasional
finding in multiple sclerosis.
- Injury to supranuclear
structures, as in progressive supranuclear palsy.
- Very rarely, disorders
of higher brain structures, including
the parietal lobes of the cerebral cortex.
Thiamine deficiency
can cause ophthalmoparesis in susceptible persons; this is part of the
syndrome called Wernicke encephalopathy. The causal pathway by which this
occurs is unknown. Intoxication with certain substances, such as phenytoin,
can also cause ophthalmoparesis.
Treatment and prognosis depend on the underlying condition.
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