Intracranial Pathways of Infection From Diseases of the Sphenoid and Ethmoid Sinuses

Abstract

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 sphenoid sinus and basisphenoid bone, the ethmoid labyrinth and the region of the cribriform plate. The superior and middle turbinâtes are included. The frontal sinuses and antrums are routinely opened and investigated, but are not included in this study, since serial section of so large a block is not feasible. The block is neither opened nor probed, but after gross inspection it is decalcified and then studied in serial sections which are cut coronally (fig. 2). On only three occasions did we find gross evidences of bone necrosis and an obvious source of infection.We have been able to demonstrate microscopically the origin of the infection in the sphenoid and ethmoid sinuses and to trace the spread to the meninges in many cases of so-called cryptogenic bacterial menin¬ gitis, or that of undetermined origin. In other instances, the assumption that the meningitis was due either to a coexisting mastoiditis or to pneumonia was proved to be wrong and the true focus of infection in the sinuses established. From the Laryngological Service and the Laboratories of the Mount Sinai Hospital.