Ophthalmoparesis

Overview
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.

Classification
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".

Types of ophthalmoplegia are:
 * Progressive external ophthalmoplegia
 * Supranuclear ophthalmoplegia

Causes
Ophthalmoparesis can result from disorders of various parts of the eye and nervous system:


 * The orbit of the eye, including mechanical restrictions of eye movement, as in Graves disease.
 * The muscle, as in progressive external ophthalmoplegia or Kearns-Sayre syndrome
 * 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.

Differential Diagnosis
Causes
 * Acute cranial polyneuropathy
 * Adie syndrome
 * Bilateral third nerve involvement
 * Botulism
 * Brainstem stroke
 * Diptheria
 * Drugs
 * Iris injury
 * Meningitis
 * Myasthenia gravis
 * Tetanus
 * Midbrain lesion
 * Vasculitis

Treatment and prognosis
Treatment and prognosis depend on the underlying condition.