Orbital vascular malformations: determining outflow with Valsalva CT angiography

Hyperostosis associated with orbital vascular malformation

A previously healthy adult male presented with a slowly enlarging orbital mass associated with 5 mm of non-pulsatile proptosis. On imaging, a soft tissue lesion with avid contrast enhancement and associated bony hyperostosis was noted. The lesion and hyperostotic bone were surgically debulked, and significant arterial bleeding was noted intraoperatively consistent with an arteriovenous malformation. Histopathologic analysis revealed a vascular malformation with enhanced microvasculature infiltrating the periosteum. While vascular lesions elsewhere in the body can be associated with skeletal changes, bony hyperostosis is a rare feature of orbital vascular malformations.

Orbital Vascular Malformations: Relationship Between Enophthalmos and Clinically Apparent Distensibility with Valsalva

PURPOSE

Determining the hemodynamic characteristics of an orbital vascular malformation is a critical step in management. The purpose of this study is to assess the relationship between enophthalmos and clinically apparent distensibility of orbital vascular malformations, to optimize imaging and treatment.

METHODS

In this cross-sectional cohort study consecutive patients at a single institution were screened for study entry. Data extracted included age, sex, Hertel measurements, presence or absence of distensibility during the Valsalva maneuver, whether lesions were primarily venous or lymphatic based on imaging, and location of the lesion relative to the globe. Enophthalmos was defined as ≥ 2 mm difference from the opposite side. Parametric and nonparametric statistics were used, and linear regression was performed to examine factors predictive of Hertel measurement.

RESULTS

Twenty-nine patients met the inclusion criteria. Relative enophthalmos ≥2 mm was significantly associated with distensibility ( p = 0.03; odds ratio = 5.33). Distensibility and venous dominant morphology were the 2 most important factors associated with enophthalmos on regression analysis. The relative position of the lesion anterior or posterior to the globe did not have a significant bearing on baseline enophthalmos.

CONCLUSIONS

The presence of enophthalmos increases the likelihood that an orbital vascular malformation is distensible. This group of patients was also more likely to be characterized by venous dominant malformations. Baseline clinical enophthalmos may serve as a useful surrogate marker for distensibility and venous dominance, which may be useful in guiding the selection of appropriate imaging.