It may be caused by taking cold, thus producing passive congestion of the brain.
"The People's Common Sense Medical Adviser in Plain English" by R. V. Pierce
Passive congestion is caused by interference with the return of the current of blood from a part.
"Special Report on Diseases of the Horse" by United States Department of Agriculture
More important, because productive of less tractable lesions, is passive congestion of the digestive organs.
"Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 4" by Various
There is more frequently acute than passive, obstructive and dyspnoeic congestion.
"New, Old, and Forgotten Remedies: Papers by Many Writers" by Various
This organ is commonly found in a state of passive congestion, while the color of its tissues is slightly darkened.
"A System of Practical Medicine by American Authors, Vol. I" by Various
In the passive case the links are the items and each row of the matrix M is associated with a route between a sensor node and the sink. A test is positive if a path is congested, namely, if it contains at least one congested link.
Graph-Constrained Group Testing