Fusobacterium necrophorum an Underrecognized Cause of Petrous Apicitis Presenting with Gradenigo Syndrome: A Case Report

Objective: Rare disease Background: With the advent of antibiotics, petrous apicitis (PA), inflammation of the petrous temporal bone, has become a rare complication of otitis media. Even more uncommon is Gradenigo syndrome (GS), a result of PA, characterized by a triad of otitis media or purulent otorrhea, pain within the regions innervated by the first and second division of the trigeminal nerve, and ipsilateral abducens nerve palsy. Recent literature has demonstrated increasing reports of Fusobacterium necrophorum isolated in cases of GS. Case Report: A 21 -year -old man presented with otalgia, reduced hearing, and severe headache. Examination revealed rightsided purulent otorrhea, anesthesia within the trigeminal nerve distribution, and an ipsilateral abducens nerve palsy. F. necrophorum was isolated from an ear swab and a blood culture. Computed tomography and magnetic resonance imaging (MRI) demonstrated otomastoiditis, PA, cavernous sinus thrombosis, and severe stenosis of the petrous internal carotid artery. He was treated with intravenous benzylpenicillin, underwent a mastoidectomy and insertion of a ventilation tube, and was started on a 3 -month course of dabigatran. Interval MRI showed improved internal carotid artery caliber, persistent petrous apex inflammation, and normal appearance of both cavernous sinuses. Follow-up clinical review noted persistent abducens and trigeminal nerve dysfunction. Conclusions: We identified 190 cases of PA; of these, 80 presented with the classic Gradenigo triad. Fusobacterium sp. were cultured in 10% of GS cases, making them the most frequent isolates. Due to the fastidious nature of F. necrophorum, it may be underrepresented in the historical literature, and we recommend that empiric antibiotics cover anaerobic organisms.