An important controversial issue is the interpretation of the pathology of primary demyelinating processes of the central nervous system. Neuropathologists have had considerable difficulty in agreeing on the significance of the vascular and perivascular reactions often observed with demyelinating diseases of the central nervous system. One group of investigators speaks of such conditions as degenerative and another as inflammatory. A conciliatory attitude is taken by workers who claim that the perivascular reaction is the expression of so-called symptomatic inflammation, a local reaction to disintegrated material. This controversy has run its gamut in the evaluation and interpretation of multiple sclerosis, diffuse sclerosis and the demyelinating encephalomyelitides following vaccination and infectious diseases, such as measles, scarlet fever, influenza and rabies.
PATHOGENESIS
Multiple Sclerosis.
—One needs only cite Hassin's 1 opinion that this disease is degenerative and that the perivascular reaction is formed mainly, if not exclusively, of gitter cells. Lymphocytes, according to