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[Orbital Compartment Syndrome Perhaps Secondary to Intra-Orbital Fluid Retention and Orbital/Palpebral Emphysema Following Frontotemporal Craniotomy for an Unruptured Cerebral Aneurysm:A Case Report].

A 58-year-old woman underwent left frontotemporal craniotomy for clipping of an unruptured cerebral aneurysm. A small defect was accidentally created in the orbital roof intraoperatively. The patient developed left eyelid edema and ocular pain after recovery from anesthesia. The following day, the eyelid edema worsened, and she had difficulty opening her eyes. On the 9th postoperative day, she noticed diminished visual acuity and diplopia in her left eye when she was able to spontaneously open her eyes. Ophthalmological evaluation revealed mild left visual loss, decreased light reflex, ophthalmoplegia, ptosis, and chemosis. Computed tomography(CT)/magnetic resonance imaging revealed left proptosis, optic nerve stretching, intra-orbital fluid retention, and orbital/palpebral emphysema. She was diagnosed with orbital compartment syndrome(OCS)and received conservative treatment;however, her visual acuity did not improve. OCS observed after cerebral aneurysm surgery is rare;to date, only 24 cases have been reported in the available literature. Although the mechanism of OCS after craniotomy is unclear, it may be attributed to ocular compression by a muscle flap or increased intra-orbital pressure secondary to venous congestion. In the present case, the left superior ophthalmic vein and cavernous sinus were not clearly visualized on CT angiography. Therefore, we concluded that the right superior ophthalmic vein and superficial facial veins underwent dilatation and served as collateral circulation of the left orbital venous system. We speculate that OCS occurred secondary to increased intra-orbital pressure, possibly caused by inflow of cerebrospinal fluid with air into the orbit through a small bone defect that was accidentally created during craniotomy in a setting of orbital venous congestion.