It is well known that cerebral symptoms may occur in infections and toxemias, especially when the condition is severe. Little if any attention has been paid to the explanation of these symptoms. Considerable work has been done in cases of syphilis and metallic poisonings in which similar symptoms have been exhibited since Nissl1 and Alzheimer2 described changes in the small vessels in the pia and cerebral cortex under the title "Endarteritis Syphilitica of the Small Cortical Vessels."
The effect on the small vessels would probably have little clinical significance were it not for the fact that interference with the blood supply to the cortex results. The mildest changes are those resulting from a general decrease in the blood supply to the brain, because of slight narrowing of the lumens of the small vessels. As a result, changes in the ganglion cell occur which are entirely comparable to cloudy