The pathology of rabies in the central nervous system

A mild degree of cerebral edema is present in many cases. In a series of 24 autopsied cases of human rabies2 the brain weights were reported to be about 10 to 20% greater than normal. Although a few markedly edematous brains have been reported in human cases (one weighing 1590 g,2 one 1570 g,3 and another 1870 g4) massive cerebral swelling is rarely seen in rabies. It is difficult to determine the relative degree to which respiratory insufficiency or arrest play in the production of this cerebral swelling. Uncal or cerebellar tonsillar herniation is rarely reported, and clinical papilledema and increased cerebrospinal fluid pressure are not noted until there are severe respiratory problems. 5•6 The parenchyma of the CNS shows little gross abnormality. Focal congestion may be seen in the white matter as well as in the tectum of the brain stem. Frank parenchymal hemorrhages are rarely seen. Focal parenchymal and meningeal blood vessel congestion is also commonly described in the spinal cord.