A 74-year-old immunocompetent man admitted for severe retro-orbital headache was diagnosed with isolated sphenoiditis. At the time of scheduled surgery, the patient was mildly obtunded, and a head CT revealed a temporal lobe abscess. The patient underwent a left temporal craniectomy and a bilateral endoscopic sphenoid sinusotomy, which revealed gross fungal debris. The patient made a full recovery with resolution of abscess and sinus findings. Suspicion for intracranial infection should be raised in any sinus patient with neurological changes. Early diagnosis with imaging studies is extremely important for surgical drainage before permanent neurological sequelae.