Internuclear Ophthalmoplegia

The internuclear ophthalmoplegia is characterized by paralysis of Augenadduktion during horizontal viewing movements, but not in convergence. It can be unilateral or bilateral.

At horizontal viewing movements of the medial longitudinal fasciculus allows on each side of the brain stem, the coordination of the abduction of an eye with the adduction of the other eye. The medial longitudinal fasciculus connects the following structures:

The internuclear ophthalmoplegia is characterized by paralysis of Augenadduktion during horizontal viewing movements, but not in convergence. It can be unilateral or bilateral. At horizontal viewing movements of the medial longitudinal fasciculus allows on each side of the brain stem, the coordination of the abduction of an eye with the adduction of the other eye. The medial longitudinal fasciculus connects the following structures: the nucleus VI. Cranial nerves (controls the lateral rectus muscle, which is responsible for the abduction) The center adjacent to horizontal eye movements (paramedian pontine reticular formation) The core of the contralateral III. Cranial nerves (controls the medial rectus muscle, which is responsible for the adduction), the medial longitudinal fasciculus also connects vestibular nuclei with the core of III. and IV. cranial nerves. A internuclear ophthalmoplegia is caused by a lesion of the medial longitudinal fasciculus. In younger patients, the disorder is usually caused by multiple sclerosis and can occur on both sides. In the elderly, internuclear ophthalmoplegia is typically caused by strokes and one-sided. Rarely is the cause in a Arnold-Chiari malformation, neurosyphilis, Lyme disease, tumor disease, head trauma, eating disorders (eg. B. Wernicke encephalopathy, pernicious anemia) or intoxication (z. B. with antidepressants or opioids). When a lesion in the medial longitudinal fasciculus signals from the center to horizontal eye movements to III. Cranial nerves is blocked, the eye on the affected side can not adduct over the center line (or adducted only weakly). The affected eye adducted normal for convergence because convergence requires no signals from the Center for horizontal eye movements. This finding differs a internuclear ophthalmoplegia from a paralysis of the III. Cranial nerve that affects the adduction at convergence (this paralysis also because it causes limited vertical eye movements, ptosis and Anomalies of pupillary differs). During a horizontal eye movement to the opposite side of the affected eye horizontal double images emerge; when abduzierenden eye nystagmus often occurs. Sometimes, a two-sided vertical nystagmus occurs while attempting to look upward. Treatment depends on the underlying disease. One and a half syndrome This unusual syndrome occurs when a lesion damages the Center for horizontal eye movements and the medial longitudinal fasciculus on the same side. The eyes can move horizontally in any direction, but the eye on the affected side can not abduct; the convergence is not affected. Causes of one and a half syndrome may be multiple sclerosis, an infarct, bleeding and tumors. Under treatment (eg. B. radiotherapy for tumors or treatment of multiple sclerosis), an improvement occur, it is, however, after a heart attack often limited.

Health Life Media Team

Leave a Reply