Facial Colliculus Syndrome

Constellation of neurological signs due to a lesion at the facial colliculus, involving

* Abducens nerve (CN VI) nucleus
* Facial nerve (CN VII) fibres at the genu
* Medial longitudinal fasciculus

and resulting in peripheral facial palsy and conjugate gaze palsy.

The facial palsy is due to interruption of the ipsilateral facial nerve fibres at the genu as they arch behind the abducens nerve (CN VI) nucleus (thus forming the colliculus).

The conjugate gaze palsy is due to involvement of innervation not only to the ipsilateral abducens nerve to lateral rectus, but also to the interneurons projecting into the medial longitudinal fasciculus which contribute to innervation of the contralateral medial rectus (thus coordinating conjugate gaze). This is not however always the case (this case), as you can see the dysconjugate gaze on the T2 FSE)
Aetiology

Causes of facial colliculs syndrome vary by age:

* Young:
o tumour
o demyelination (e.g MS)
o viral inection (e.g rhomboencephalitis)
* Older:
o vascular (e.g stroke – this case)

References:

D.A. Jacobsa and S.L. Galettaa “Neuro-Ophthalmology for Neuroradiologists” American Journal of Neuroradiology 28:3-8, January 2007

For more images of the case and many more, please visit Radiopaedia.org here.

Credit: Dr Frank Gaillard