Objective:

To describe a case of progression from apparent trochlear nerve palsy, to wall-eyed monocular internuclear ophthalmoplegia (WEMINO), to wall-eyed bilateral internuclear ophthalmoplegia (WEBINO) with unilateral lower motor neuron (LMN) facial palsy. 

Background:

Various descriptions of INO with cranial nerve palsies are in the literature, but we report a patient with a remarkably instructive stepwise evolution. 

Design/Methods:

Review of records of a patient with diplopia at our institution.

Results:

A 42-year-old woman presented acutely with oblique binocular diplopia worsening on right gaze and left head tilt, with left hypertropia. Trochlear nerve palsy was suspected but contrasted MRI brain with orbits, and initial CSF testing were unrevealing. On day 3, the hypertropia partly improved but she developed left eye adduction deficit. Given the fluctuation, myasthenia gravis was considered high in the differential diagnosis while test results were awaited. On day 7, she developed LMN left facial palsy and bilateral adduction deficit with abducting eye nystagmus, leading to the realization that a single progressing lesion in the pontine tegmentum could explain her entire sequence of events. Repeat MRI confirmed a minute enhancing lesion in the floor of the fourth ventricle corresponding to the dorsomedial surface of the left facial colliculus and bilateral medial longitudinal fasciculi (MLF), likely of demyelinating etiology. Her pending CSF tests returned with 7 oligoclonal bands. She received intravenous methylprednisolone and her symptoms nearly resolved by day 14.

Conclusions:

This patient presented with evolving symptoms that appeared to localize to the trochlear nerve initially, but lacked imaging correlate. It is clear in retrospect that her initial presentation represented a skew deviation from early INO, progressing to WEMINO and eventually WEBINO with unilateral fascicular facial palsy. The anatomical correlate was confirmed on repeated imaging. Her clinical course beautifully illustrates the importance of lesion localization for etiological diagnosis.