Abstract
BackgroundCogan’s anterior internuclear ophthalmoplegia (INO) is characterized by INO with inability to converge and commonly thought to be due to rostral midbrain lesion. A lesion outside midbrain that causes unilateral Cogan’s anterior INO combined with upgaze palsy and ataxia are rarely described.Case presentationA 67-year old male presented with left Cogan’s anterior internuclear ophthalmoplegia (INO), left appendicular ataxia and bilateral upgaze palsy. A Magnetic Resonance Imaging (MRI) and Magnetic Resonance Angiography (MRA) brain showed a left dorsal tegmental infarct at the level of pontomesencephalic junction.ConclusionsThis case highlights the clinical importance of Cogan’s anterior INO in combination with upgaze palsy and ataxia, and report possible site of lesion in patients with such constellation. Clinicians should consider looking for cerebellar signs in cases of Cogan’s anterior INO, apart from just considering localizing the lesion at the midbrain.
Highlights
Cogan’s anterior internuclear ophthalmoplegia (INO) is characterized by INO with inability to converge and commonly thought to be due to rostral midbrain lesion
Internuclear ophthalmoplegia (INO) is a discrete localizing sign which narrows down the lesion involving medial longitudinal fasciculus (MLF) anywhere at the paramedian tegmentum from caudal pons to midbrain [1]
In which anterior INO shows convergence impairment, whereas posterior INO exhibits intact convergence [3]. He proposed that the presence of anterior INO helps to further localize the lesion over the most rostral portion of MLF conducting the impulses from the pretectal region to the 3rd nerve nucleus in midbrain, whereas posterior INO indicates lesions at the level of the 4th ventricles in pons [4]
Summary
This is a rare case report with a constellation of unilateral Cogan’s anterior INO, upgaze palsy with ataxia due to a dorsal tegmental lesion at pontomesencephalic junction. Clinicians should consider looking for cerebellar sign in cases of Cogan’s anterior INO, apart from just considering localizing the lesion over the midbrain. INO with vertical gaze palsy should alert clinicians to look for lesions near pontomesencephalic junction and cerebellar involvement. INO with ataxia is mostly due to vascular infarct
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