Bacterial pyomyositis of the extraocular muscles: case report and systematic review

To describe the manifestations and treatment of extraocular muscle (EOM) bacterial pyomyositis.

A systematic review following PRISMA guidelines and a case report.

PubMed and MEDLINE databases were searched for case reports and case series of EOM pyomyositis using the term "extraocular muscle" combined "pyomyositis" and "abscess". Patients were included as bacterial pyomyositis of the EOMs when there was a response to antibiotics alone or if a biopsy was consistent with the diagnosis. Patients were excluded when pyomyositis did not involve the EOMs or when diagnostic tests or treatment were not in keeping with the diagnosis of bacterial pyomyositis. An additional patient with bacterial myositis of the EOMs, treated locally, was added to the cases identified in the systematic review. Cases were grouped for analysis.

There are 15 published cases of EOM bacterial pyomyositis including the one reported in this paper. Bacterial pyomyositis of the EOMs typically affects young males and is caused by Staphylococcus species. Most patients present with ophthalmoplegia (12/15; 80%), periocular edema (11/15; 73.3%), decreased vision (9/15; 60%) and proptosis (7/15; 46.7%). Treatment involves antibiotics alone or in combination with surgical drainage.

Bacterial pyomyositis of the EOM presents with the same signs as orbital cellulitis. Radiographic imaging identifies a hypodense lesion with peripheral ring enhancement within the EOM. An approach to cystoid lesions of the EOMs is helpful in reaching the diagnosis. Cases can be resolved with antibiotics aimed at treating Staphylococcus, and surgical drainage may be required.