Further, Knauer reports that even at the height of post-rheumatic stupor, external stimuli make some impression, in that a thoughtful facial expression appears. In deep stupors, such as occurred in our series, this response is not seen. The same phenomenon of “rousing,” larval in Knauer’s cases, is often well marked in encephalitis lethargica and is, of course, a pathognomonic symptom of delirium.
As will be discussed in a later chapter on the literature, reactions resembling benign stupors occur as a result of toxins, particularly following acute rheumatism. Recently the medical profession has been called on to treat many cases of encephalitis lethargica where similar symptoms are observed.