July 6, 2015
A 69-year-old woman with a history of right craniotomy for SDH evacuation presents 19 months later with right periauricular soft tissue swelling.
Bone Flap Osteomyelitis with Subperiosteal Abscess
- Background: Patients who have undergone a craniotomy may present with infection at or near the incision site. The process may spread by proximity to the devascularized craniotomy bone flap, which may become an infected bone sequestrum. However, the superficial soft tissue swelling is not always present.
- Clinical Presentation: Pain, fever, erethyma, headache, altered mental status, and rarely, a draining fistula
- Key Diagnostic Features:
- CT: Bone flap erosions of the outer and inner tables
- MR: Loss of the normal high T1-weighted bone flap marrow signal, with adjacent dural thickening and subperiosteal and subgaleal enhancement in the overlying scalp. An epidural or subperiosteal collection may be seen, visible on postcontrast imaging, which is suggestive of an abscess.
- DDx:
- Aseptic flap necrosis
- Bone flap tuberculosis
- Treatment: Patient is placed on broad-spectrum antibiotics, which are subsequently tapered when a specific organism is isolated.
- In this case, the microorganism was Serratia Marcescens. This patient had the devitalized bone flap removed with concurrent mesh cranioplasty.
