Intra-arterial administration of antibiotics for refractory skull base osteomyelitis

We report two cases of elderly diabetic men with skull base osteomyelitis (SBO) originating from malignant external otitis (MEO). In both, a devastating infection and neural paralysis deteriorated after conventional therapy, including long-term intravenous administration of culture-directed antibiotics with strict control of blood sugar levels and surgical debridement of infectious granulation tissue. Since poor perfusion of antibiotics in the lesion may be associated with serious nature of MEO/SBO, we administered antibiotics intra-arterially via a retrograde catheter with the tip set at the proximal point of the external carotid artery to increase the tissue drug concentration in the maxillary artery (MA) and ascending pharyngeal artery (APA) supply areas, in which intense inflammation was observed. This intra-arterial administration of antibiotics (IA therapy) followed by long-term intravenous and oral antibiotic treatments eliminated their infection and no recurrence was observed in 2 years follow-up period. Interestingly, CT images of angiography via the catheter demonstrated stronger enhancement in the MA supply area compared to the APA supply area and IA therapy was more effective in the former. These results suggest that IA therapy, which might achieve high antibiotic concentration at the site of infection, is effective in patients with MEO/SBO refractory to conventional treatments.