Ophthalmoparesis or ophthalmoplegia refers to paralysis of one or more extraocular muscles

Extraocular muscles

The extraocular muscles are the six muscles that control the movements of the eye . The actions of the extraocular muscles depend on the position of the eye at the time of muscle contraction.-List of muscles:-Importance:...

 which are responsible for eye movements. It is a physical finding in certain neurologic

Neurology

Neurology is a medical specialty dealing with disorders of the nervous system. Specifically, it deals with the diagnosis and treatment of all categories of disease involving the central, peripheral, and autonomic nervous systems, including their coverings, blood vessels, and all effector tissue,...

 illnesses.

Classification

Ophthalmoparesis can involve any or all of the extraocular muscles, which include the superior recti

Superior rectus muscle

The superior rectus muscle is a muscle in the orbit. It is one of the extraocular muscles. It is innervated by the superior division of the oculomotor nerve...

, inferior recti

Inferior rectus muscle

The inferior rectus muscle is a muscle in the orbit.-Actions:It depresses, adducts, and helps extort the eye.The inferior rectus muscle is the only muscle that is capable of depressing the pupil when it is in a fully abducted position....

, medial recti

Medial rectus muscle

The medial rectus muscle is a muscle in the orbit.As with most of the muscles of the orbit, it is innervated by the inferior division of the oculomotor nerve ....

, lateral recti

Lateral rectus muscle

The lateral rectus muscle is a muscle in the orbit. It is one of six extraocular muscles that control the movements of the eye and the only muscle innervated by the abducens nerve, cranial nerve VI....

, inferior oblique

Inferior oblique muscle

The Obliquus oculi inferior is a thin, narrow muscle placed near the anterior margin of the floor of the orbit.-Action:Its actions are lateral rotation, elevation and abduction of the eye....

 and superior oblique muscle

Superior oblique muscle

For the abdominal muscle see: Abdominal external oblique muscleThe superior oblique muscle, or obliquus oculi superior, is a fusiform muscle originating in the upper, medial side of the orbit which abducts, depresses and internally rotates the eye...

s.

It can also be classified by the directions of affected movements, e.g. "vertical ophthalmoparesis".

Causes

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

• The orbit
  Orbit (anatomy)
  In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents...
  
   of the eye, including mechanical restrictions of eye movement, as in Graves disease.
• The muscle
  Muscle
  Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
  
  , as in progressive external ophthalmoplegia or Kearns-Sayre syndrome
  Kearns-Sayre syndrome
  Kearns–Sayre syndrome also known as oculocraniosomatic disease or Oculocraniosomatic neuromuscular disease with ragged red fibers is a mitochondrial myopathy with a typical onset before 20 years of age...
  
  .
• The neuromuscular junction
  Neuromuscular junction
  A neuromuscular junction is the synapse or junction of the axon terminal of a motor neuron with the motor end plate, the highly-excitable region of muscle fiber plasma membrane responsible for initiation of action potentials across the muscle's surface, ultimately causing the muscle to contract...
  
  , as in myasthenia gravis
  Myasthenia gravis
  Myasthenia gravis is an autoimmune neuromuscular disease leading to fluctuating muscle weakness and fatiguability...
  
  .
• The relevant cranial nerves (specifically the oculomotor
  Oculomotor nerve
  The oculomotor nerve is the 3rd of 12 paired cranial nerves. It enters the orbit via the superior orbital fissure and controls most of the eye's movements, including constriction of the pupil and maintaining an open eyelid by innervating the Levator palpebrae superiors muscle. The optic nerve is...
  
  , trochlear
  Trochlear nerve
  The trochlear nerve is a motor nerve that innervates a single muscle: the superior oblique muscle of the eye....
  
  , and abducens), as in cavernous sinus syndrome or raised intracranial pressure.
• The brainstem nuclei
  Nucleus (neuroanatomy)
  In neuroanatomy, a nucleus is a brain structure consisting of a relatively compact cluster of neurons. It is one of the two most common forms of nerve cell organization, the other being layered structures such as the cerebral cortex or cerebellar cortex. In anatomical sections, a nucleus shows up...
  
   of these nerves, as in certain patterns of brainstem stroke such as Foville's syndrome
  Foville's syndrome
  Foville's syndrome is caused by the blockage of the perforating branches of the basilar artery in the region of the brainstem known as the pons....
  
  .
• White matter tracts connecting these nuclei, as in internuclear ophthalmoplegia
  Internuclear ophthalmoplegia
  Internuclear ophthalmoplegia is a disorder of conjugate lateral gaze in which the affected eye shows impairment of adduction. When an attempt is made to gaze contralaterally , the affected eye adducts minimally, if at all. The contralateral eye abducts, however with nystagmus...
  
  , an occasional finding in multiple sclerosis
  Multiple sclerosis
  Multiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...
  
  .
• Dorsal midbrain structures, as in Parinaud's syndrome
  Parinaud's syndrome
  Parinaud's Syndrome, also known as dorsal midbrain syndrome is a group of abnormalities of eye movement and pupil dysfunction. It is caused by lesions of the upper brain stem and is named for Henri Parinaud , considered to be the father of French ophthalmology...
  
  .
• Certain parts of the cerebral cortex
  Cerebral cortex
  The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
  
   (including the frontal eye fields), as in stroke
  Stroke
  A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
  
  .
• Toxic envenomation
  Envenomation
  Envenomation is the process by which venom is injected into some animal by the bite of a venomous animal. Many kinds of animals, including mammals , reptiles , spiders , insects , employ venom for hunting and for self defense...
  
   by mamba
  Mamba
  Mambas, of the genus Dendroaspis , are a group of highly venomous, fast-moving land-dwelling snakes of Africa. They belong to the family of Elapidae which includes cobras, coral snakes, taipans, brown snakes, tiger snakes, death adders, kraits and, debatably, sea snakes...
  
  s, taipan
  Taipan
  The taipans are a genus of large, fast, highly venomous Australasian snakes of the elapid family.-Overview:The taipan was named by Donald Thomson after the word used by the Wik-Mungkan Aboriginal people of central Cape York Peninsula, Queensland, Australia.There are three known species: the coastal...
  
  s, and kraits.

Thiamine

Thiamine

Thiamine or thiamin or vitamin B1 , named as the "thio-vitamine" is a water-soluble vitamin of the B complex. First named aneurin for the detrimental neurological effects if not present in the diet, it was eventually assigned the generic descriptor name vitamin B1. Its phosphate derivatives are...

 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

Phenytoin

Phenytoin sodium is a commonly used antiepileptic. Phenytoin acts to suppress the abnormal brain activity seen in seizure by reducing electrical conductance among brain cells by stabilizing the inactive state of voltage-gated sodium channels...

, can also cause ophthalmoparesis.

Treatment and prognosis

Treatment and prognosis depend on the underlying condition. For example, in thiamine deficiency, treatment would be the immediate administration of vitamin B1.