The spectrum of ocular motor abnormalities as the only clinical sign of brainstem lesions

Abstract

Background The widespread use of magnetic resonance imaging (MRI) revealed an increasing variety of ocular motor abnormalities as the only clinical sign of (mainly ischemic) brainstem lesions. Methods This paper reviews the variety of such abnormalities. Results Ocular motor abnormalities as the only clinical sign of MRI-documented brainstem lesions include complete and partial 3rd, 4th and 6th nerve palsies, vertical gaze palsies, crossed vertical gaze palsy, monocular elevation paresis, internuclear ophthalmoplegia, horizontal gaze palsy, horizontal gaze palsy with facial palsy, 1 1 2 -syndrome, 1 1 2 -syndrome with facial palsy (“ 8 1 2 -syndrome”), upbeat nystagmus, horizontal-rotatory nystagmus, horizontal nystagmus, skew deviation, and ocular tilt reaction. Conclusions Brainstem lesions causing isolated ocular motor abnormalities may be divided into 4 main groups. (A) Lesions involving infranuclear ocular motor nerve segments cause complete and partial 3rd, 4th and 6th nerve palsies. (B) Lesions affecting nuclei related to eye movements such as 3rd and 6th nerve nucleus, rostral interstitial nucleus of the medial longitudinal fasciculus, interstitial nucleus of Cajal, nucleus intercalatus Staderini are followed by horizontal and vertical gaze palsies, upbeat nystagmus, horizontal-rotatory nystagmus. (C) Lesions interrupting internuclear connections lead to internuclear ophthalmoplegia, monocular elevation paresis, skew deviation and ocular tilt reaction. (D) Combined lesions of nuclear and internuclear or infranuclear structures are the anatomical basis of 1 1 2 -syndrome, 8 1 2 -syndrome, or horizontal gaze palsy with facial palsy. The clinical significance of these disorders is not known.