ACUTE HÆMORRHAGIC LEUCO‐ENCEPHALITIS

Summary Twenty‐three cases of acute hæmorrhagic leuco‐encephalitis have been described in the literature under this title. The clinical and pathological features of these cases have been reviewed. The condition is characterized by the sudden onset of speech disturbances, motor paralyses and urinary incontinence. Rapid progression to coma and death has occurred in all cases. The illness generally follows a respiratory infection after a short latent interval. It may also arise spontaneously, or follow the administration of certain drugs or chemical agents. At autopsy, the lesions in the cerebral hemispheres are almost entirely confined to the white matter. Elsewhere in the central nervous system, this predilection is not obvious. The lesions consist of areas of hæmorrhage, perivascular exudate, fibrinoid degeneration of blood vessels, especially of small veins, together with focal and perivascular areas of demyelination and microglial proliferation. Present evidence suggests that the condition may result from hypersensitivity—a cerebral Arthus phenomenon, and that this state may be induced by different allergens. Auto‐sensitization may be involved. The relationship of this condition to various types of “hæmorrhagic encephalitis”, and to acute disseminated encephalo‐myelitis is discussed. It would appear that what is known as acute hæmorrhagic leuco‐encephalitis in Australia, the United Kingdom and certain parts of Europe, is called acute necrotizing hæmorrhagic encephalopathy in the United States. The use of cerebral biopsy in an attempt to obtain a definitive diagnosis during life is advocated. The early administration of cortisone in the diagnosed case is suggested.