Sunday, 20 May 2012

Facial Colliculus Syndrome MRI Brain

A 50 yo male with recent onset left lateral rectus palsy and left side lower motor neuron facial palsy.
MRI Diffusion shows a punctate focus of recent ischemia with restricted diffusion in dorsal aspect of Pons at the floor of floor ventricle which corresponds to fascial colliculus. 
Facial Colliculus Syndrome


The facial colliculus is an anatomical elevation in the floor of the fourth ventricle located medial to the sulcus limitance.
Not formed by the facial nerve nucleus, but by the abducens nerve and the motor fibres of facial nerve loop dorsal to the 6th CN nucleus before leaving the brainstem known as internal genu of facial nerve resulting a bump at the floor of fourth ventricle called facial colliculus.
There for a nuclear lesion of abducens nerve in pons is frequently associated with an ipsilateral lower motor neuron pattern of facial weakness.

Causes of facial colliculs syndrome vary by age. In young age group tumour, demyelination and viral inection where as in elderly people ischemic lesions are common causes.
Clinical presentation of facial colliculus syndrome is due to a lesion at the facial colliculus Involves
1. Ipsilateral lower motor neuron pattern of Facial nerve palsy. .
2. Abducens nerve (CN VI) nucleus result in ipsilateral lateral rectus palsy.
3. Some times conjugate gase palsy due to an associated contra lateral medial rectus palsy due to involvement of medial longitudinal fasciculus.

Millard Gubler syndrome, a related syndrome to facial colliculus (dorsal pons) resulting in ipsilateral 6th and 7th nerve palsy +/- contra lateral hemiparesis.


References:
Localization in Clinical Neurology,  By Paul W. Brazis
Jacobs DA, Galetta SL. Neuro-ophthalmology for neuroradiologists. AJNR
Sinnatamby CS. Last's Anatomy, Regional and Applied.
Clemente CD. Anatomy, A Regional Atlas of the Human Body.

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