Retrolaminar chiasmal migration of intraocular silicone oil masquerading as subarachnoid hemorrhage on CT head

Abstract

Silicone oil is used as a long-term treatment agent for intraocular tamponade to repair retinal detachments following vitrectomy. Retrolaminar migration of oil into the optic nerve is a rare complication, with migration into the optic chiasm being even more rare. Following imaging, this entity can be misdiagnosed as acute hemorrhage, aneurysm, or neoplasm on imaging possibly leading to delay of care or unnecessary interventions. We will discuss a case where the imaging findings were thought to represent a small acute subarachnoid hemorrhage possibly related to an aneurysm involving the distal right internal carotid artery.

Keywords: CT head; Misdiagnosis; Retrolaminar migration; Seizure; Silicone oil; Subarachnoid hemorrhage.

Fig. 1

STAT CT head without contrast. CT of the head from an axial view (A), a coronal view (B), and a sagittal view (C). The red arrow indicates the silicone oil in all views, and is high density that can be seen in the right aspect of the optic chiasm as well as in the adjacent portions of the right optic nerve and optic tract. Without proper knowledge of patient history, the hyperintensity can be mistaken as a hemorrhage or an aneurysm. The blue brackets demonstrate the suprasellar space. The purple arrow demonstrates the anterior cerebral artery. The yellow arrow demonstrates the sella.

Fig. 2

CT angiogram of the head following transfer to the neuro ICU. CT angiogram images with an axial view (A) and coronal view (B). Images show high-density silicone, red arrow, in the right ocular vitreous cavity related to prior silicone oil injection for treatment of retinal detachment. There is also migrated silicone in the intraorbital segment of the right optic nerve. The brown arrow demonstrates the optic nerve. The white arrow represents the lens. The green arrows point to the cavernous sinus.

Fig. 3

Axial view of CT angiography with contrast. CT angiography demonstrates that the lesion, red arrow, in the right optic chiasm and right ocular vitreous cavity does not enhance with contrast. There is no evidence of cerebral aneurysm or vascular malformation. The purple arrow shows the middle cerebral artery.