Michael L. Slavin

MRI in optic neuritis

Magnetic resonance imaging (MRI) demonstrated several hyperintense white matter lesions in the brain of 15/20 patients with acute optic neuritis. The patients were categorized into three groups based on history and physical. Group 1 (11/20 patients) consisted of patients with isolated optic neuritis, six of which had abnormal MRI scans. Group 2 (8/20 patients) consisted of patients with probable multiple sclerosis (MS). Group 3 (one patient) consisted of patients with definite MS. All of the patients in Groups 2 and 3 had abnormal MRI scans. There was no difference between the extent or location of MRI demonstrated lesions between these three groups of patients with optic neuritis. Patients with isolated optic neuritis were just as likely to have extensive areas of involvement on MRI, as patients with probable or definite multiple sclerosis.

Unusual associations of downbeat nystagmus

Two patients presented with downbeat nystagmus and lesions remote from the cranio-cervical junction: one with decompensated aqueductal stenosis; the second with midbrain infarction. Unopposed upward drift of the eyes due to to vestibular or pursuit imbalance seem unlikely in the pathogenesis in these cases. An abnormality in the vertical gaze holding center is compatible with eye movement recordings in one case.

Segmental arteriolar sheathing: A sign of retinal emboli

In five patients with amaurosis fugax and visible retinal emboli, an additional finding was observed, consisting of focal arteriolar mural opacification. Typical atheromatous emboli were observed in each case, either in proximity to the vascular sheathing, or in the fellow eye. One case demonstrated the occurrence of an embolus, followed by focal progressive arteriolar opacification ensuing over the next few months. We believe that focal arteriolar sheathing is due to local arteriole wall reaction provoked at the time of embolus impaction, and that this sign in isolation is as useful a ‘calling card’ of embolic retinal disease as the appearance of the cholesterol embolus itself.