Extensive skull base osteomyelitis is a severe complication of malignant otitis externa (MOE). It is most commonly diagnose in patients with diabetes and in immuno compromised patients with bacterial and/or fungal infection. The primary infection is often bacterial with fungal superinfection. Pseudomonas aeruginosa is the causative pathogen in 50%-90% of cases, although other agents may be isolated.
A 76-year-old man was refer to our Ear Nose and Throat (ENT) department in 2015 with a 4-month history of worsening right-side MOE with the involvement of the ipsilateral otomastoid foramen and temporal bone. The patient had been treat empirically with oral ciprofloxacin (Ciprofloxacina; Sandoz S.P.A., Varese, Italy) 500 mg/day for 2 months but show little clinical improvement.
They presented with persistent temporal headache, otalgia, milky otorrhea, right facial palsy (House–Brackmann grade 4), and left hemiparesis as a result of a stroke 16 years earlier. Computed tomography (CT) revealed occlusion of the right external auditory canal, chronic osteomyelitis of the right temporal bone extending to the right mastoid and tympanic cavity, erosion of the ossicular chain, partial erosion of the inner ear, and preservation of a small portion of the cochlea.
Malignant otitis externa is the osteomyelitis of the temporal bone that usually occurs in elderly diabetic or otherwise immuno compromised patients; occasionally, the infection can spread and cause a skull base osteomyelitis. The disease is associated with serious complications with a cranial nerve involvement and high mortality and morbidity rates. MOE is also reported in immuno compromised or diabetic children; however, the incidence is not as common as in elderly diabetic patients.
The spectrum of human infections with Corynebacterium is broad ranging from community-acquired infections such as conjunctivitis, pharyngitis, genitourinary tract infections, prostatitis, skin and soft-tissue infections, and breast abscess to nosocomial-acquired infections such as cerebrospinal fluid infections, pneumonia, intravenous catheter-related bloodstream infections, endocarditis, post-surgical infections, urinary tract infections, and peritoneal dialysis-related peritonitis.
The patient was treat exclusively with antibiotic therapy. He underwent surgery only to obtain biopsies of the mastoid cortex and tympanic cavity for histopathologic and microbiologic examination. The introduction over the years of newer, more effective, and less toxic antibiotics has reduced the role of surgery. In our case, clinically there was a marked progression of unilateral MOE with a severe involvement of the skull base, the contralateral side, and the cervical spine inferiorly.
Bilateral skull base osteomyelitis is very rare, and there are no reports of bilateral involvement of the skull base from extension of unilateral disease. However, cases of bilateral skull base osteomyelitis concomitant with or following bilateral MOE have been described. Unilateral MOE complicated by extensive skull base osteomyelitis in a non-diabetic and immunocompetent patient is uncommon.
An extensive skull base osteomyelitis extending up to the contralateral petrous temporal bone and cervical vertebra is exceedingly rare. This case presented multiple concurrent factors: prior radiotherapy treatment, an extensive otitis externa, a rare bacterial infection; perhaps, the sum of these conditions could have caused the extraordinary extension of the infection to the skull base. We recommend early detection of such cases in non-diabetic and immunocompetent patients.