MS borderline conditions are considered by some to be variant forms of multiple sclerosis. Others consider multiple sclerosis borderline conditions to be similar but completely separate diseases from MS.

These so-called borderline conditions also go by the name “idiopathic inflammatory demyelinating diseases” or IIDDs. Those who consider them to be multiple sclerosis variants essentially believe that their distinctions come down to their severity, their chronicity, and the clinical course that each one of them tends to follow. This way of viewing the conditions is preferable to the perspective that describes them as distinct diseases for an important reason: it encourages one to think about multiple sclerosis in a bigger picture perspective.


Characterizing MS Borderline Conditions


Why is it important to think about multiple sclerosis in a bigger picture perspective? The answer to this question is basically that it is important to do so because looking at any disease from this perspective gives one insight into the commonalities between the different variants. Emphasizing what the MS borderline conditions have in common over what distinguishes them makes it possible to identify the common factors and mechanisms behind the demyelination and inflammation of the nervous tissue.

Some examples of multiple sclerosis borderline conditions include standard MS, leuodystrophy, Marburg MS, Tumefactive MS, Balo concentric MS, Devic’s disease, optic neuritis, and others. Chronic fatigue syndrome could also be included under this rubric, as could Guillain-Barré syndrome. Devic’s disease is divergent from standard MS in a number of ways, some subtle and others not so subtle. For one, both conditions result in demyelination and in nervous tissue lesions. However, while  in standard MS, the autoimmune attacks involve the immune system’s T-cells, in Devic’s disease, the autoimmune attacks involve antibodies. Secondly, the lesions tend to be concentrated in the spinal cord and optic nerve in Devic’s disease, while in standard MS, the brain is also affected. Thirdly, the causes of Devic’s disease have been tied to various systemic diseases, certain medications, and certain viruses. As for standard MS, its ultimate cause remains unspecified, but it has been tied to various triggers, including vitamin D deficiency and EBV.

Guillain-Barré is distinct from standard MS because it causes demlyelination in the peripheral nervous system rather than in the brain and spinal cord. About 40% of its cases are triggered by infections. Additionally, men are more likely to be affected by this condition than women, while MS is more prevalent among women than it is among men. Marburg MS, another borderline MS condition, is fast progressing, and it is also a lethal form of MS.