A 55-year-old man presented with recurrent right sided ear and post auricular pain. He had been previously treated with multiple course of oral antibiotics and was referred to otolaryngology for follow up. Computed tomography (CT) of the right ear and neck showed right sided chronic mastoiditis, erosion of the inferior mastoid cells, extension of the infection into the neck spaces and formation of a Bezold's abscess in the ipsilateral sternocleidomastoid muscle, extending into the retropharyngeal space (Fig. 1). On examination his temperature was 100.1 F. His only significant finding was post-auricular erythema and tenderness. White cell count was 16,700 cells/cmm with 80% neutrophils. His sedimentation rate was 112 mm/hr and CRP was 43. The patient was admitted and treated empirically with intravenous piperacillin/tazobactam 4.5 g every 6 h.
The patient underwent a right tympanomastoidectomy, canaloplasty, incision and drainage of the Bezold's abscess. Intraoperative findings included abscess fluid collection with surrounding necrotic tissue in the superior aspect of the ipsilateral sternocleidomastoid muscle and extensive granulation and inflammatory tissue with fibrosis in the mastoid air cell and middle ear. Histopathology of the right mastoid revealed fibroconnective tissue with chronic inflammation and possible osteomyelitis of the bone. No granulomas were seen and the acid fast and fungal stains were negative.
Postoperatively the patient continued to complain of hearing loss, severe intermittent headache and low grade fever. No focal neurological signs were present. He had mild neck pain on movement but no nuchal rigidity. The right posterior auricle was tender. There was no drainage or fluctuation over the surgical incision. MRI of the brain, triple phase bone scan and a Gallium scan (Fig. 2) and SPECT CT scan (Fig. 3) revealed extensive involvement of the infection to the petrous portion of the temporal bone, a retropharyngeal collection, intracranial dural enhancement and skull base. This confirmed the diagnosis of skull base osteomyelitis.
Antibiotics were changed to intravenous vancomycin 1 g every 12 h, cefepime 2 g every 8 h and metronidazole 500 mg every 8 h for broader empiric coverage. HIV test, RPR, tuberculosis interferon-gamma release assay and blood cultures were all negative. Staphylococcus epidermidis was recovered from one of three operative tissue cultures, but was not regarded as a pathogen. Otherwise all cultures were negative, including fungal and mycobacterial cultures. After four weeks of intravenous antimicrobials the patient's ESR and white cell count normalized. Repeat MRI brain showed interval improvement however with the intracranial extension of infection a longer duration of intravenous antibiotics continued. The patient had serial ESR, CRP and Gallium scans (Fig. 2) and CT SPECT scans (Fig. 3). After six months of treatment he had complete resolution of infection and antibiotics were discontinued.