Optic Neuropathy Caused by an Isolated Mucocele in an Onodi Cell

Abstract

A rare case of retrobulbar optic neuropathy caused by an isolated mucocele in an Onodi cell is presented. A 63-year-old man suffering from left recurrent optic neuropathy had shown improved visual acuity with steroid treatment at the age of 48 and 56 years. Impaired visual acuity and blurred vision in the left eye appeared again, and a marked inferior decrease in the left visual field was noted. Although axial computed tomography (CT) showed no abnormal findings, magnetic resonance imaging (MRI) revealed a small squamous-shaped lesion (17 × 17 × 7.3 mm) in the left posterior ethmoidal air cell (Onodi cell) hanging over the left optic nerve. Endoscopic sinus surgery was performed. The optic canal was extruding into the Onodi cell cavity, and the superior bony wall of the canal was eroded by the mucocele. The isolated mucocele in the Onodi cell seemed to be compressing the optic nerve downward and causing retrobulbar optic neuropathy. An Onodi cell lesion, even if it was isolated and small, would cause optic neuropathy. MRI and coronal CT scanning should be performed for the diagnosis and preoperative planning in a case of retrobulbar optic neuropathy.

Recovery of Visual Function in a Patient with an Onodi Cell Mucocele Compressive Optic Neuropathy Who Had a 5-Week Interval between Onset and Surgical Intervention: A Case Report

“…Neuroimaging is central to the detection of the lesion, and coronal and sagittal views are recommended, as axial CT images alone may not reveal the mucocele if the thickness of the slices used is greater than the width of the Onodi cell [5]. …”

Acute visual loss by an Onodi cell

“…Optic neuropathy is a well known complication of paranasal sinusitis and mucoceles,7 but there are only few cases in literature which describe an isolated mucocele in an Onodi cell as the cause of optic neuropathy 89 The mechanism of retrobulbar optic neuropathy is a mechanical compression of the optic nerve, because it often runs within the small cavity of the Onodi cell 6…”

“…9 Coronal computed tomography is helpful in the differential diagnosis of an osseous origin and preoperative evaluation 23 8 9 …”

“…Orbital inflammation associated with paranasal sinusitis is a well known cause of optic neuropathy,7 but an isolated mucocele of an Onodi cell causing optic neuropathy is rare 89 We report a case of acute visual loss caused by an isolated mucocele of an Onodi cell.…”

Onodi Cell Mucocele Causing Acute Vision Loss

“…Onodi cells have been reported to occur in approximately 7% of the general population in computed tomography (CT) studies, but in cadaveric studies they have been reported to be present in up to 60% of specimens [3]. The discrepancy may be due in part to the fact that older studies using thick section axial CT without isotropic resolution were less sensitive for detecting small air cells which are often flat in configuration within the plane of axial section [4]. Identification of an Onodi cell is of importance prior to sinonasal surgery due to the close anatomic relationship between this posterior air cell and the optic nerve ( [5]; Fig.…”