Theories abound because no one knows the answers yet

It is difficult to think of an aetiological theory that has not been suggested to explain multiple sclerosis. Disconcertingly, however, many of the aetiological questions asked over 150 years ago are still unanswered.1 Is the disease due to a vascular defect as initially suggested by Rindfleisch in 1863, who noted a blood vessel in the centre of each plaque, or is it a defect in the glial tissue as argued by Charcot in 1868 after he viewed and drew the glial and nerve changes under his microscope? Oppenheim was certain that multiple sclerosis was caused by environmental toxins. In the middle of the 20th century interest centred around the possibility that it was an immunological disease and, more recently, a genetic disease.

Perhaps the most enduring questions concern a potential infectious agent. In 1894 Pierre Marie, a former student of Charcot, argued strongly that infection was the cause of multiple sclerosis and that those who disagreed had not read his papers. He did not know the …