The pathologic process and the pathways of intracranial infection from the paranasal sinuses have not been investigated as routinely or as thoroughly as those of the mastoid bone and petrous pyramid. Except for gross examination at the necropsy table, little effort has heretofore been made to study the sinuses microscopically even in cases of bacterial meningitis of undetermined pathogenesis. Since in only a small percentage of instances is the lesion visible macroscopically, a large number of lesions starting in the sinuses have undoubtedly been overlooked and the primary foci not discovered. It was once assumed that in the presence of suppuration of the middle ear the meningitis was otitic in origin even though pathologic proof of this origin did not exist.
During the past seven years, we have been removing the paranasal sinuses en bloc in all cranial autopsies in cases of meningitis. The block consists (fig. 1) of the