Internuclear ophthalmoplegia is an entity arising from lesions of the medial longitudinal fasciculus. The term was first introduced in 1922 by Lhermitte,* and shortly thereafter the condition was divided by Lutz † into the anterior and posterior types. It has been described as a characteristic clinical picture, manifested primarily by paresis of the medial rectus muscle on attempted lateral gaze, other signs of a paralysis of the third cranial nerve being absent. Associated findings of nystagmus, skew deviation, vertigo, nausea, and vomiting have been described.3
The medial longitudinal fasciculus is the important reflex pathway connecting the vestibular nuclei to the motor nuclei of the extraocular muscles and of the head and neck. Phylogenetically, it is one of the first tracts of the brain to appear, being present in the Cyclostomata and observed to be an important reflex pathway in fishes.4 In mammalian embryos it is among the first
FINE M, MacGLASHAN CB. Unilateral Internuclear Ophthalmoplegia of Vascular Origin: A Report of Four Cases. AMA Arch Ophthalmol. 1956;56(3):327–337. doi:10.1001/archopht.1956.00930040335002
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