LESIONS

A Guide to Localisation in Neurology

Case 23 - Weakness and abnormal eye movements

Outcome

A CT was performed, showing a large pontine haemorrhage, centred towards the right side of the pons and extending upwards towards the midbrain.

In the images below, the left column shows axial CT images descending from midbrain to pons (A-D), while the right column shows coronal images, anterior (E) to posterior (H). Blood is seen as a bright substance, marked by the red arrowheads.

The patient was discussed with the on-call neurosurgery team. Unfortunately there was no surgical option possible to treat this - the blood was intraparenchymal rather than in the ventricle or in the space surrounding the cerebellum, both of which can sometimes be addressed surgically. 

She was taken to the intensive care unit and ventilated for 24 hours in addition to receiving aggressive blood-pressure lowering with intravenous beta blockers and nitrates. 

The next day she was reviewed after several hours with sedation paused. The examination found the following signs:

• She remained ventilator-dependent and deeply unresponsive
• She made little response to noxious stimuli applied to limbs, sternum or supraorbital notches.
• On oculocephalic testing her eyes moved with the head, indicating absent bilateral vestibulo-ocular reflexes

• She had no response to blink reflex testing in either eye
• Pupils were non-reactive to light and mid-sized

While the patient did not satisfy formal criteria for death by neurological criteria (sometimes referred to as 'brainstem death'), it was felt that this haemorrhage had caused overwhelming neurological damage and was unsurvivable. The team discussed her condition with her relatives who were clear that the patient would not wish to be kept alive in the event of such an illness. The team made the decision to withdraw life-support and the patient passed away that afternoon with her family present.

Sudden-onset left hemiplegia and UMN facial weakness with right abducens palsy due to a right pontine haemorrhage, followed by coma then development of severe brainstem damage, with a fatal outcome.

1. Nerve VI is long and can be affected by lesions anywhere between its nucleus and fascicles in the pons through to its destination in the orbit. It can also be affected by elevated ICP as a false-localising sign
2. VI lesions can be cross-localised with other features, if present, to find the site. In this case, ipsilateral VI with contralateral hemiplegia localises to the inferior pons. 
3. A small minority of intracerebral haemorrhages affect the pons. These may be mild, but if they are large and produce early coma, as in this case, then survival is unlikely.