Extraocular muscle enlargement

Abstract

Extraocular muscle enlargement can occur secondary to a range of orbital and systemic diseases. Although the most common cause of extraocular muscle enlargement is thyroid eye disease, a range of other inflammatory, infective, neoplastic, and vascular conditions can alter the size and shape of the extraocular muscles. Imaging with computed tomography and magnetic resonance imaging plays an essential role in the workup of these conditions. This article provides an image-rich review of the wide range of pathology that can cause enlargement of the extraocular muscles.

High index of suspicion: diagnosing a carotid-cavernous fistula

“…This engorgement can manifest as non-specific enlargement of the extraocular muscle on the MRI with clinical signs of diplopia and bilateral abducens nerve palsy. The presence of proptosis and diplopia can mimic other diseases and can be a falsely localising sign making the diagnosis of carotid-cavernous fistula harder to make, and can cause confusion when other causes of extraocular muscle enlargement need to be explored 8 9…”

Non-traumatic extraocular muscle haemorrhage associated with anticoagulation use

“…NTOH related to the EOM is a rarely diagnosed clinical condition with characteristic radiological features 5. In a case series conducted by Chan et al , intra/juxta-oculomuscular haemorrhage was described to occur spontaneously in the absence of underlying vascular malformations.…”

“…EOM enlargement can result from a range of different pathologies, including inflammatory, infective, vascular and neoplastic conditions (table 1). 5…”

“…Various conditions could result in extraocular muscle enlargement including inflammation, infection, malignancy, amyloidosis and vascular conditions, with thyroid eye disease being the most common cause (table data obtained from Rana et al 5). …”

“…Radiological findings on both CT and MRI scans vary depending on the haematoma age (table 2). 5 However, since MRI can more accurately identify haemoglobin and its breakdown products, serial MRI scans can be more helpful in supporting the diagnosis of intramuscular haemorrhage 5 6…”