Non-traumatic extraocular muscle haemorrhage associated with anticoagulation use

Background

Non-traumatic orbital haemorrhage (NTOH) is an uncommon event which has been associated with several underlying aetiologies including vascular and bleeding abnormalities, inflammation, infection and malignancy. Based on anatomical patterns, NTOH can be classified into five different categories (box 1).1

NTOH in relation to extraocular muscles (EOMs) was described in a number of cases, in which the haemorrhage occurred mainly within the muscle sheath or the intermuscular septum. Fewer cases reported the haemorrhage to be located within the muscle belly.1 Chan et al concluded that vascular risk factors, namely, hyperlipidaemia, hypertension and antiplatelet use, could be considered as possible predisposing factors for non-traumatic EOM haemorrhage.1

Direct oral anticoagulants (DOACs) are increasingly prescribed for prevention and treatment of thrombotic vascular events.2 3 Rivaroxaban, a DOAC which works by inhibiting factor Xa, is favoured in some patients for its high compliance rate being prescribed as a single daily dose for venous thromboembolism prevention and treatment.2–4

Case presentation

A woman in her late 60s presented to the emergency department with a 2-day history of sudden-onset, pressure-like pain above her left eye. The pain radiated along the left temporal region and across the inner corner of her eye. The pain was aggravated by ocular movement, bright light, lying on the affected side and bending forward. Apart from increased stress, there were no acute events, specifically, no trauma, respiratory tract infection or forceful straining. The patient did not use spectacles or contact lenses and had never undergone ocular surgery or had orbital implants.

Following recurrent deep vein thrombosis, rivaroxaban 10 mg once daily was started as a life-long anticoagulation treatment, to which the patient was compliant. Other medical conditions included: osteoarthritis, dyspepsia, depression and asthma. In addition to anticoagulation, regular medications included fluoxetine, gabapentin and tramadol with topical ibuprofen as needed. There was no known history or family history of bleeding disorders. No documented COVID-19 infection was reported prior to the presentation, and she had received two doses of COVID-19 vaccination. The patient was not undergoing any other medical investigation.

Examination revealed only tenderness at the supraorbital foramen. The patient had normal eye movement, with exacerbation of pain on left lateral gaze. Visual fields appeared to be normal, and cranial nerves were intact with no peripheral focal neuropathy. A specialist ophthalmological examination confirmed normal colour vision and visual acuity, normal intraorbital pressure, and healthy optic discs and maculae.

Investigations

Initial non-contrast CT of the head identified a 21×12×12 mm intraconal, hyperdense soft tissue mass, slightly deviating the left optic nerve medially. The mass was thought either to rise from the left lateral rectus muscle or to be centred over it. While haematoma was considered as a possible diagnosis, malignancy with an intratumoural haemorrhage was also a concern. An MRI orbit with contrast revealed a well-defined oval lesion arising from the left lateral rectus muscle. The lesion was peripherally enhancing and mildly hyperintense on T1/T2. On susceptibility-weighted imaging (SWI) sequence, a small focus of low SWI signal, representing either haemorrhage or calcification, was noted. As the MRI scan was inconclusive and malignancy was still a concern, the patient had CT scan of the thorax, abdomen and pelvis, with no obvious malignancy identified.

Laboratory tests showed no coagulopathy (prothrombin time 10.5 s, activated partial thromboplastin time 24.6 s, Clauss fibrinogen 3.1 g/L) and haemoglobin was 143 g/L (normal 115–160 g/L).

Treatment

Rivaroxaban was withheld after discussing risks and benefits with the patient and her partner. The patient was also started on 60 mg of prednisolone once daily, with a plan of reducing the dose by 10 mg every 3 days. The pain was well controlled with oral analgesia, and the patient was discharged home with urgent follow-up.

Outcome and follow-up

The patient was readmitted the following week due to increased pain concerns, and further imaging was undertaken to rule out any complication. A repeat MRI concluded an appearance of resolving haematoma with significant size reduction of the previously described mass, which was now showing as high T1 signal. Afterwards, the patient was followed up by the medical team and the ophthalmology specialists. When reviewed 2 weeks after the initial presentation, the medical team decided to restart oral anticoagulation (rivaroxaban) and finish the last few days of the steroid course. At the 6-week follow-up appointment, the patient’s symptoms continued to improve, although she was still experiencing occasional shooting pain in the left frontal area. Ophthalmological examination remained unremarkable apart from a finding of mild nuclear cataract. A 4-month follow-up MRI demonstrated a further reduction in the haematoma and a slight reduction in the size of the belly of the left lateral rectus muscle, focal intramuscular T2 hyperintensity and resolving T1 hyperintensity with the surrounding retrobulbar fat returning to normal. MRI at 6 and 8 months showed that the left lateral rectus haematoma had continued to consistently reduce in size (figure 1).

Figure 1

Reduction of haematoma over serial MRIs. (A) Initial MRI: axial MRI showing a well-defined oval lesion arising from the left lateral rectus muscle. (B) MRI 7 days post-presentation: axial MRI demonstrating an appearance of resolving haematoma with significant size reduction. (C) MRI 8 months after presentation: axial MRI revealing significant resolution of the haematoma.