Case presentation: DMS, 65 years old, holocranial headache with frontal predominance for 15 days, mental confusion, edema in the left orbital and periorbital region, and presented congestion of the left maxillary sinus and hypodensity in the left frontal. Lumbar puncture: leukocytes 213 - predominance of lymphocytes, glucose 68, protein 186, with negative fungal analysis or culture.. She underwent therapy with ceftriaxone and vancomycin. After 5 days, course with right hemiparesis and clear appearance of left frontal subdural empyema adjacent to the frontal hypodensity; There was a decrease in the level of consciousness, with worsening hypodensity e now with left subdural empyema. Subjected to drainage, without clinical response. Metronidazole, amphotericin and polymyxin added. The exams did not demonstrate cavernous sinus thrombosis or any other finding that could explain the ocular edema. Cerebrospinal fluid culture, culture of secretion drained from the empyema and brain biopsy were performed, with negative results. Patient died. Discussion: The most affected are young male adults. There is difficulty in relating cause and effect between meningitis and sinusitis because, un like abscesses, it mostly originates from chronic sinusitis. The clinical picture includes fever, headache that increases in intensity, neck stiffness, irritability and delirium. There are two routes of infection from the paranasal sinuses to the intracranial cavity: Retrograde thrombophlebitis through diploic veins of the skull and ethmoid bone or communicating veins (Breschet’s diploic veins) - by continuity; and by direct extension of sinus infection through congenital or traumatic dehiscences, erosion of the sinus wall, that is osteomyelitis, and existing foramina (e.g. olfactory nerves) - contiguity. Complications: meningitis, epidural abscess, subdural empyema, venous sinus thrombophlebitis and brain abscess. The frontal sinus is the most commonly associated with intracranial infection. In subdural empyema, only large collections cause a mass effect, leading to the appearance of an evident clinical picture. Anaerobic germs represent 29% of endocranial complications. Non-betahemolytic streptococcus are the most commonly found. Staphylococcus is isolated in subdural empyemas and brain abscesses, as well as in cavernous sinus thrombophlebitis and osteomyelitis. Pneumococcus and Haemophilus influenzae are more commonly found in meningitis of upper respiratory tract etiology. Anaerobes may occur in up to 50% of non-traumatic brain abscesses. Negative cultures occur in 21% of cases. Final comments: A CNS infection resulting from infectious sinusopathy is serious, includes disabling sequelae and is difficult to diagnose due to the chronicity of the symptoms and the exclusive attribution of the symptoms to sinusopathy, as in the case of our patient. CSF and empyema cultures have high rates of false negatives.