Abnormal anatomy of inferior orbital fissure and herniation of buccal fat pad

Lateral orbital wall anomaly in a patient with thyroid eye disease

An isolated defect in the lateral orbital wall is an uncommon occurrence, although cases of orbital floor, roof, and medial wall spontaneous dehiscence have been described in the literature. Here, we describe a lateral orbital wall defect in a patient with thyroid eye disease - which may be related to bony remodeling or may represent a rare congenital anomaly. Computed tomography (CT) prior to decompression surgery revealed a defect in the left lateral orbital wall. At the time of orbital decompression, prolapse of buccal fat into the orbit was noted once the subperiosteal plane was entered along the lateral orbital wall in the area of this bony defect. Literature review revealed only a few previous reports of lateral wall abnormalities, including two involving the inferior orbital fissure; one other case was associated with Down syndrome, and other reports consist of sphenoid hypoplasia associated with neurofibromatosis.

Herniation of orbital fat through the inferior orbital fissure and into the infratemporal fossa: a cadaveric case report and review

Orbital fat herniation is primarily in a subconjunctival location. However, herniation through the inferior orbital fissure (IOF) has been scantly reported. Here, we report a cadaveric case of herniation of orbital fat through the inferior orbital fissure and into the infratemporal fossa. The cadaver's orbital anatomy and orbital fat herniation were found during routine dissection. The details of this case are reported. We also discuss anatomical variations of the inferior orbital fissure as well as the related vascular and nervous system structures related to orbital fat herniation. This is a rare case of a cadaver with this anatomical abnormality.

Prolapse of Orbital Fat through the Inferior Orbital Fissure: Description, Prevalence, and Assessment of Possible Pathologic Associations

BACKGROUND AND PURPOSE

A few patterns of orbital fat prolapse have been described. Some are associated with disease, and others may mimic a neoplasm. We have observed prolapse of orbital fat into the infratemporal fossa via the inferior orbital fissure on MR imaging. The clinical relevance of this finding, if any, is unknown. The purposes of this study were to describe the MR imaging appearance of orbital fat prolapse through the inferior orbital fissure, to estimate the prevalence of this finding, and to assess possible pathologic associations.

MATERIALS AND METHODS

For this retrospective study of 228 orbital MR imaging examinations, 3 neuroradiologists independently assessed the presence of prolapse on high-resolution T1-weighted images. Discrepancies were resolved by consensus, and interobserver agreement was calculated. Patient demographics, indications for imaging, and pertinent clinical history were recorded. One-way analysis of variance and the Fisher exact test were used to assess possible associations between prolapse and specific patient characteristics.

RESULTS

Orbital fat prolapse through the inferior orbital fissure was observed in 20/228 patients (9%). This finding was unilateral in 11 patients (55%) and bilateral in 9 patients (45%). There was no significant association with age, sex, obesity, Graves disease, hypercortisolism, prior orbital trauma, proptosis, or enophthalmos. Interobserver agreement was 90%.

CONCLUSIONS

Prolapse of orbital fat into the infratemporal fossa via the inferior orbital fissure is a relatively common finding on orbital MR imaging that has no identified pathologic association. Neuroradiologists should recognize this finding so as not to report it as pathologic.