Ophthalmoplegia

Any combination of abnormal eye movements may be presented:

• Oculomotor nerve palsy is generally associated with downwards and outwards positioning of the ipsilateral eye. Because this cranial nerve also innervates the pupillary sphincter and levator palpebrae superioris, this form of OP is accompanied by mydriasis and ptosis.
• Isolated trochlear nerve palsy is related to preponderance of inferior oblique muscle function, resulting in upwards movements of the ipsilateral eye while gazing downwards and upon adduction.
• Functional impairment of the abducens nerve results in lateral rectus muscle paralysis and consequently disturbed outwards movements of the affected eye.
• Multiple nerve palsies give rise to more complex anomalies corresponding to the actions of maintained eye muscle function.

OP patients often claim visual impairment, mainly diplopia. The degree of diplopia is dependent on the current direction of gaze. Patients may "learn" to compensate for OP by adopting abnormal head positions. This condition is commonly referred to as ocular torticollis [8] [9].

OP is diagnosed clinically and has to be associated with an underlying disorder. Demographic parameters, symptom onset and disease progression, the presence of unilateral or bilateral complaints and concomitant pathologies should be considered when establishing a list of differential diagnoses. With regards to cranial nerve palsies, extensive knowledge regarding the course of cranial nerves coordinating eye muscle contractions is required to deduce the site of injury from clinical symptoms [1]. Brain imaging may be indicated to visualize lesions of the central nervous system and in this context, magnetic resonance imaging is generally the most sensitive technique. However, computed tomography is usually preferred for an evaluation of orbital tissues [10]. Images obtained by means of computed tomography may, for instance, depict spindle-shaped, enlarged extraocular muscles, as is characteristic of Graves disease. Other entities may be associated with abnormally thin, atrophic ocular musculature. Laboratory analyses of blood samples are usually carried out to assess the patient's general condition and to reveal the underlying pathology. Cerebrospinal fluid specimens may be obtained for similar reasons.

Ophthalmoplegia (OP) generally refers to the presence of eye movement alterations that are caused by paralysis of the extraocular musculature. Because cranial nerve palsies account for considerable shares of OP cases [1], extraocular muscles shall be enumerated according to their respective innervation:

• The oculomotor nerve (III) accounts for the coordination of superior and inferior rectus muscles, medial rectus muscles, and inferior oblique muscles.
• The trochlear nerve (IV) is required for superior oblique muscle function.
• The lateral rectus muscles are innervated by the abducens nerve (VI).

In the broader sense, OP may also describe clinical symptoms arising from internal muscle paralysis. In detail, pupillary sphincter and dilator and/or the ciliary muscle may be affected. These muscles mediate narrowing and widening of the pupil, a means of adaptation to light intensity, and changes of lens shape, thus adapting the eye to short range focus. The pupillary sphincter and ciliary muscle are innervated by the oculomotor nerve.

Cranial nerve palsies may be caused by space-occupying lesions such as a cerebral aneurysm or brain tumors or may be triggered by an increased intracranial pressure, inflammation [2], infection or stroke. Intrinsic muscle dysfunction is less common but may be observed in cases of multiple sclerosis [3], myasthenia gravis, and diabetes mellitus [4], among others. These are systemic disorders not usually restricted to ocular muscles. Congenital OP may indicate developmental defects [5] or hereditary disorders such as congenital muscle dystrophy [6]. Additionally, mutations of mitochondrial DNA are commonly associated with myopathy, including but not limited to OP [7].

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10. LeBedis CA, Sakai O. Nontraumatic orbital conditions: diagnosis with CT and MR imaging in the emergent setting. Radiographics. 2008;28(6):1741-1753.