Hypothesis: the significance of Winterbottom's sign.

Swollen glands in the neck in African sleeping sickness is usually considered to be a sign of peripheral trypanosomiasis without cerebral involvement. Experimental evidence of connection between these glands and the ventricles of the brain is reviewed. The evidence suggests that Winterbottom's sign may indicate also a cerebral infection. It also suggests that trypanosomes may enter the brain via the lymphatic system.