Unilateral mydriasis without ophthalmoplegia--a sign of neurovascular compression? Case report

We aimed to demonstrate the use of neuroimaging studies in vascular compression of the oculomotor nerve.

A 24-year-old woman was noted by her dentist to have anisocoria, with the left pupil being larger than the right. After detailed ophthalmologic and neurological examination, we proceeded to perform neuroimaging. T2-weighted images (2 mm) and constructive interference in steady-state (0.3 mm) images were utilized.

Magnetic resonance imaging showed that duplicated left superior cerebellar artery, a prominent posterior communicating artery, and a posterior cerebral artery combined to compress the superomedial portion of the left oculomotor nerve.

With continued improvements in neuroimaging, we think that more cases of isolated cranial neuropathies previously labeled as "idiopathic" will be shown to result from vascular compression.