Vascular loop syndrome

A  50 y o male with typical left hemi facial spasm.

Routine MRI axial T2w sequences were absolutely normal except tortuous vertebro basilar with marked tortuousity of left sided vertebral.
With history of left hemi facial spasm area of interest was left side 7-8th CN Complex, study repeated with very thin axial sections at the level of IAC, showed tortuous left vertebral artery causing an obvious compression over left 7- 8^th CN Complex.

Imaging diagnosis: Vascular loop syndrome with 7th - 8th CN Compression,  Hemifacial spasm. 

Vascular loop syndrome

Abnormal anatomical variation or course of vessel causing symptomatic compression over cranial nerves at IAC or Cp Angle cistern.

Spasmodic hyperfunction of nerve due to compression.

Compression of 5th CN (Trigeminal nerve) present with trigeminal neuralgia and 7th CN (Facial nerve) present with hemi facial spasm.

Trigeminal nerve involvement due to vascular loop is more common than Facial nerve.

'Kindling' theory, pulsatile vessel coming in contact with nerve induces ectopic excitations which travel retrogradly back to the Cranial Nerve nucleus.

Routine T2w images used for brain may be insufficient.

High index of suspicion with high resolution T2w sections in the region of posterior fossa are must.

Age of presentation is older age group after 65, though it's anatomical variation or abnormality.

Related post: Vascular loop syndrome - 5th CN compression, Trigeminal neuralgia

Let's see few doubtful cases of VASCULAR LOOPs.

This case comes from general practitioner with right sided headache. High-resolution axial T2 weighted images show a thin tortuous vessel mostly anterior inferior cerebellar artery with intracanalicular course on right side around seventh and eighth cranial nerve complex. However there is hardly any deviation of nerves from its normal course. Finding mentioned in the report with significance to be given with clinical correlation.

This case again comes with left-sided headache. High-resolution axial T2 weighted images show a thin tortuous vascular loop in between left side seventh and eighth cranial nerve complex without any deviation of nerve from its normal course. Finding mentioned in the report with significance to be given with clinical correlation.

This patient came with a requisition mentioning clinical suspicion of left side trigeminal neuralgia where an artery mostly superior cerebellar traversing very closely over cisternal portion of left side trigeminal nerve distorting the shape and normal straight course of left side trigeminal nerve, deviating the trigeminal nerve laterally consistent with clinical diagnosis of left side trigeminal neuralgia.