Trigeminal neuralgia due to vascular compression

Case contributed by Hoe Han Guan
Diagnosis probable

Presentation

Intermittent right otalgia (each episode lasts for 5 minutes) and mild sensorineural hearing loss.

Patient Data

Age: 60 years
Gender: Female

At the heavily T2 weighted high resolution scan (T2 MX3D) of posterior fossa, it shows the right superior cerebellar artery indents onto the right trigeminal nerve at the superior surface of the nerve near to the root entry zone (which is 2mm anterior to root entry zone).
No significant discrepancy in nerve girth seen between trigeminal nerve on either side.
No abnormal trigeminal nerve enhancement (especially the cisternal segment).

The right superior cerebellar artery can be traced from its origin at basilar artery, which seen looping downward touching the superior aspect of right trigeminal nerve. The left trigeminal nerve root entry is clear from any vascular compression.

Normal signal intensities noted within bilateral inner ear structures.
No abnormal enhancing lesion in bilateral cerebellopontine angles and IAMs.
Normal and symmetrical enhancement of geniculate ganglion and tympanic segments of bilateral facial nerve. No abnormal facial nerve enhancement at the fallopian canal and intracanalicular segments.

Multiple hyperintense foci on both T2WI and FLAIR sequences scattered throughout bilateral white matter in cerebrum, which may represent small vessel disease.

Annotated images denote the nerve root entry right trigeminal nerve is being indented by right superior cerebellar artery at its superior surface. No external compression at left trigeminal nerve.

Case Discussion

Correlating with intermittent and excruciating pain of right otalgia, the presence of vascular compression of right superior cerebellar artery onto superior surface of right trigeminal nerve at nerve root entry zone raises high suspicion of right trigeminal neuralgia secondary due to vascular compression. No MR evidence of CP angle tumor or schwannoma.

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