Introduction Isolated sphenoid sinusitis is unusual (incidence of about 2.7% of all sinus infections) and is even rarer in children under 6 years old. It is frequently misdiagnosed because of its atypical presentation, but it threatens serious, even fatal, complications because of the sphenoid’s anatomical relationships with many intracranial structures (nerves, vessels etc). We report three cases of isolated sphenoiditis in previously healthy children with acute symptoms of CNS, which initially had raised suspicion of other conditions.

Case reports Case 1: a 4-year-old boy, with symptoms mimicking meningitis. Laboratory findings indicative for bacterial infection but “clear” CSF.

Case 2: a 12-year-old boy with dizziness and two transient episodes of visual hallucinations. No signs of infection. His symptoms initially seemed to be psychic in origin, so he was evaluated by child psychiatrists.

Case 3: a12-year-old boy, with acute headache, vomiting and dizziness. Romberg sign present, without infection findings.

In all three cases, the diagnosis of isolated sphenoiditis was revealed by head CT (the study of choice), which was performed on the suspicion of other intracranial conditions.

All cases received i.v. ceftriaxone plus clindamycin, with excellent final outcome for the first two children. The third one still has (after three months) radiological findings, so he is under ENT observation.

Conclusion Sphenoiditis can be a serious infection but is frequently misdiagnosed because of its atypical symptomatology, as in our cases. Considering that our cases presented to a provincial hospital within one year, we discuss that its rarity could be due to uncomplicated cases which did not undergo head CT scan.