From the Ear to the Brain: Otitis Externa Complicated by Coalescent Mastoiditis Leading to Temporal Lobe Abscess and Wernicke's Aphasia.

Otitis externa is typically a benign infection of the external auditory canal; however, in high-risk individuals, particularly those with poorly controlled diabetes mellitus, it may progress to severe otogenic and intracranial complications. We report a case of a 59-year-old woman with type 2 diabetes and an HbA1c of 14%, reflecting longstanding uncontrolled disease related to medication nonadherence, who developed a temporal lobe abscess and Wernicke's aphasia following inadequately treated otitis externa. At her initial emergency department (ED) visit for left-sided otalgia, otoscopic examination demonstrated erythema and crusting of the external auditory canal with an intact tympanic membrane, preserved hearing, and no mastoid tenderness. She was prescribed topical and oral ciprofloxacin but discontinued both after one day due to vomiting. Laboratory studies revealed marked hyperglycemia with otherwise normal inflammatory markers. Two weeks later, she returned with confusion, disorientation, and fluent but nonsensical speech. A CT angiogram performed for concern of acute stroke was unremarkable, while an MRI of the brain demonstrated complete opacification of the left mastoid and middle ear cavity, coalescent mastoiditis with erosion of the tegmen tympani, and a 9 × 5 × 7 mm peripherally enhancing lesion in the left middle temporal gyrus consistent with a temporal lobe abscess. CT of the temporal bone confirmed acute mastoiditis, although intracranial findings were better delineated on MRI. Blood cultures remained negative. Given the small size of the abscess and absence of mass effect, she was managed nonoperatively with intravenous cefepime and vancomycin and oral metronidazole, alongside intensive glycemic optimization. She completed a six-week antimicrobial regimen and achieved full neurological recovery with near-complete radiographic resolution. This case highlights that inadequately treated otitis externa may serve as a suspected otogenic source of intracranial abscess in patients with uncontrolled diabetes and emphasizes the importance of early MRI evaluation when neurologic symptoms arise, even when CT imaging and laboratory findings are initially reassuring.