Subperiosteal Orbital Hematoma: An Uncommon Complication of Acute Sinusitis
Non-traumatic subperiosteal orbital hematoma (SOH) is a rare disease and infrequent cause of proptosis. Isolated cases related to sudden increase in central venous pressure have been reported, as well as an association with inflammatory periorbital conditions such as sinusitis and orbital cellulitis.
It has been suggested that sinusitis-induced inflammatory response can lead to venous stasis and thrombophlebitis in the delicate subperiosteal orbital veins, leading to rupture and hematoma formation.[2,3] Anticoagulation and blood diathesis also increase risk of SOH formation. The orbital periosteum confines the hematoma within the subperiosteal potential space. Subperiosteal fluid collection in the setting of sinusitis more commonly represents an abscess, and therefore, delineating between the two entities is important for appropriate treatment. Whereas medical management is often sufficient in cases of orbital abscess and phlegmon, symptomatic subperiosteal hematoma most commonly requires surgical drainage.
A 64-year-old male with a medical history of prior orbital fracture and extensive sinus surgery initially presented to an outside hospital with symptoms of acute sinusitis. His symptoms initially improved with antibiotics, however, approximately 7 days after starting antibiotics, he began to have right orbital pain, blurry vision, and transient vision loss. He was taking aspirin and warfarin for a vascular stent. Physical examination demonstrated proptosis, decreased visual acuity, and impaired upward gaze. Computed tomography (CT) imaging showed a slightly hyperattenuating, well-circumscribed fluid collection confined within the subperiosteal space of the right orbital roof causing significant proptosis and mass effect on the superior rectus muscle and superior aspect of the globe [Figure 1]. The orbital apex and optic nerve were preserved. The collection was given a presumptive diagnosis of abscess and the patient was taken for surgery. Operatively, a superior orbitotomy was utilized to evacuate the collection, which was proven to be an organized hematoma at pathology. Cultures were negative.
A 51-year-old female with a history of extensive sinus surgery for recurrent sinusitis presented with symptoms of acute sinusitis. Symptoms transiently improved with antibiotics. Despite initial improvement, she returned complaining of increased left orbital pressure and discomfort with upward gaze. Clinical examination noted 1–2 mm downward deviation of the left pupil and diminished visual acuity. CT demonstrated a hyperattenuating subperiosteal fluid collection in the superomedial aspect of the left orbit causing mild inferolateral deviation of the globe, as well as mild proptosis [Figure 2]. This was initially diagnosed as an abscess. On further investigation, a prior diagnosis of a von Willebrand-like disorder was revealed. A superior orbitotomy was utilized to drain a maroon-colored thick fluid collection proven to be an organized hematoma at pathology. Cultures were negative.
SOH is an infrequent cause of proptosis. While several reports of orbital hematoma associated with trauma, orbital cellulitis, and increased central venous pressure are described in the literature, only a few case reports are reported in the literature describing orbital hematoma occurring in the setting of sinusitis.[2-6] The risk of developing a hematoma is increased in patients on anticoagulation or with a bleeding diathesis as in the two presented cases.
The superior and medial aspect of the orbit is the most common location of SOH. This is likely due to the rich network of subperiosteal vasculature in this location. This orbital location is adjacent to the frontal and ethmoid sinuses and is the frequent location of sinusitis-related SOH. Sinus or orbital CT is the initial imaging modality of choice. Findings that suggest a diagnosis of subperiosteal hematoma rather than abscess on unenhanced CT include a smooth, well-defined interface between the periosteum and orbital fat (no associated fat stranding) with no identifiable periosteal breech and a sharply defined, high attenuating, extraconal lesion that is biconvex with margins contained by the sutures. No contrast enhancement would be expected with hematoma.
Magnetic resonance imaging (MRI) is useful when there is an indeterminate diagnosis on CT and may increase diagnostic accuracy; however, the effect of blood product degradation on the T1- and T2-weighted MRI sequences can present a diagnostic dilemma. T1-weighted and T2-weighted image signal intensity varies temporally with blood product degradation. With acute and subacute hematoma, T1 hyperintensity and T2 hypointensity would be expected. In the late subacute stage, T2 signal intensity increases; during transition to chronic hematoma, T1 and T2 intensity decrease progressively overtime. Blood sensitive sequences such as gradient recalled echo and susceptibility-weighted images are strong detectors of blood products but can be easily degraded by magnetic field inhomogeneity, as in the orbit near the interface with aerated sinuses, facial bones, and orbital soft tissue. Diffusion-weighted imaging (DWI) is a sensitive sequence for detection of high cellularity showing high signal intensity as in the case of abscess and would demonstrate low signal intensity with hematoma.
In patients with small asymptomatic SOH, non-surgical management is the preferred method of treatment. Close clinical follow-up is recommended due to the fact that extension of SOH into the orbital apex can result in rapid onset blindness.[1,4,6] Some authors have expressed concerns that hematoma could serve as nidus for infection, potentially leading to orbital abscess formation. Nearly all reported cases of symptomatic sinusitis-induced orbital hematoma were treated surgically.[1,6]
Commonly used operative approaches for evacuation of subperiosteal collection include (1) superior or superomedial orbitotomy and/or (2) endoscopic partial ethmoidectomy with partial lamina papyracea resection. While multiple factors determine the selected surgical approach, there is a trend toward endoscopic evacuation due to decreased risk of bleeding and better esthetic outcome.
When a subperiosteal orbital fluid collection is present in the setting of sinusitis, the radiologist must consider the possibility of SOH and distinguish it from abscess due to differing treatment. Features that favor SOH on non-contrast CT are a hyperattenuating fluid collection with smooth borders, no orbital fat stranding, no appreciable periosteal breach, and biconvex shape contained by suture lines. MRI with DWI can be useful if there is doubt on CT.