Vertical Diplopia: Skew Deviation and Medullary Lesion.

CASE REPORT

A 38-year-old female developed sudden onset vertical diplopia on looking upward and towards the left side. She had left hyperopia, neck deviation to the right, left eye incyclotorsion, and right eye excyclotorsion [Figure 1]. The skew was incomitant (left hyperopia more on left gaze and less on right gaze). Alternate cover test did not reveal corrective ocular counter roll. Skew deviation is vertical ocular misalignment because of the supranuclear gaze pathway lesion.[1] It may be comitant, incomitant, or alternating. It is associated with lesions in the posterior fossa. In some cases, the condition may mimic trochlear nerve palsy. The supine upright test helps differentiate these two conditions.[2] In our case, the patient had a clear history of diplopia on looking to left and upwards as well as reduction in diplopia (reduced distance between true and false image) by upto 80% on lying down. She had no vascular risk factors. Magnetic resonance imaging showed a FLAIR hyperintense lesion in the medulla on the right side [Figure 2]. CSF examination was normal. Oligoclonal bands were negative. A provisional diagnosis of demyelinating plaque was made. She was treated with intravenous pulse methylprednisolone, followed by oral prednisolone with significant improvement.

Figure 1

Examination revealed left eyelid retraction, left hyperopia with ocular tilt, and no nystagmus. (a-f) Rest of the neurologic examination was normal

Figure 2

MRI revealed a FLAIR hyperintense lesion in the ventral right medulla

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Conflicts of interest

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