Orbital wall thickness and the spread of infection from the paranasal sinuses.

Ninety-three human skulls (80 adults and 13 children) have been examined and the extent of thin bone in the party walls between the orbit and the frontal, ethmoidal and maxillary sinuses has been assessed. Translucent bone is most often present in the lateral wall of the ethmoidal labyrinth and least often in the floor of the frontal sinus. In children such bone is present significantly less often in the roof of the maxillary sinus (P less than 0.001) than in adults. Computerized tomography scans and clinical data from 6 patients with orbital cellulitis were reviewed. In one of these an inferolateral subperiosteal abscess of the orbit was associated with a defect in the roof of the maxillary sinus. Two patients had a medial subperiosteal abscess associated with ethmoiditis and in one there was direct continuity between the abscess and the adjacent ethmoidal cells. In another case a superolateral abscess was demonstrated in continuity with a surgical defect in the floor of the frontal sinus. We conclude that the ethmoidal, frontal or maxillary sinuses may be sources of orbital infection and that spread occurs either by direct extension through the sinus wall or by local thrombophlebitis.