LESIONS

A Guide to Localisation in Neurology

Case 3. Numb face

Case

An MRI showed a lesion in the left dorsal upper pons, in the site of the principal trigeminal sensory nucleus - suggestive of demyelination.

In addition there were multiple white matter lesions in the brain, including a juxtacortical ‘U fibre’ lesion, periventricular lesions, and cerebellar lesions.

This was suggestive of multiple sclerosis (MS), meeting the criteria for dissemination in space . However, insufficient evidence was present to meet the dissemination in time criteria, so the patient underwent another MRI with contrast 3 weeks later. By this time, the pontine lesion was non-enhancing, while there were new, asymptomatic, enhancing lesions present - demonstrating dissemination in time . MS was diagnosed.

The patient was treated with B-cell depleting infusions, which were tolerated well, with a stable clinical course and no relapses, as well as stable imaging performed annually. The facial sensory loss gradually returned to normal, with only occasional intermittent cheek tingling and numb feelings.

Two years after diagnosis, she paused her infusions for family planning and had an uncomplicated pregnancy, delivering a healthy baby.

Hemifacial numbness due to a demyelinating pontine lesion as the first presentation of MS.

1. New-onset focal sensory loss, evolving over days, raises concern for inflammatory demyelination.
2. Facial numbness is a well-recognised presentation in MS
3. There is a differential to consider for this presentation, so imaging is warranted; in some people the final diagnosis is idiopathic facial numbness after investigations return negative