Intracranial complications are recognised as rare, but serious, sequelae of endoscopic sinus surgery.

A 56-year-old woman was referred after developing meningitis following elective functional endoscopic sinus surgery. Computed tomography demonstrated a significant defect of the skull base in the right posterior ethmoid, clearly visible on both coronal and sagittal sections. Operative exploration demonstrated the skull base to be intact in the posterior ethmoid area identified on the scan, and the overlying mucosa appeared undisturbed. Scans were reviewed in the light of operative findings; coronal and sagittal images were found to be reconstructions. Directly acquired coronal computed tomography, undertaken three weeks after surgery, demonstrated a complete bony plate in the right posterior ethmoid at the site previously identified as dehiscent.

We speculate that the posterior ethmoid defect was actually an artefact of reconstruction. We cannot exclude the alternative possibility of remineralisation, but given the time frame this seems unlikely. This case highlights the need for caution when interpreting reconstructed images of the thin bony plates of the skull base and lamina papyracea, as regards both clinical significance and medicolegal reporting. While virtual defects have been reported in the superior semicircular canals as a result of reconstructed images, we believe this to be the first reported case demonstrating a similar problem in the anterior skull base.