There isn't any studies, that I know of, that are specifically designed to determine impact of O6:O3 ratio on MS, so therefore you need to piece data together as best you can and try to make an informed decision on your own health.
IMO MS is not an isolated health condition in the body, any improvement in bodiliy health will have a flow on effect on the MS symptoms.
This study below, a review of an older diet heart study shows the addition of Omega 6's as a therapeutic treatment actually increased all cause mortality in heart patients:
http://www.bmj.com/content/346/bmj.e8707
Conclusions Advice to substitute polyunsaturated fats for saturated fats is a key component of worldwide dietary guidelines for coronary heart disease risk reduction. However, clinical benefits of the most abundant polyunsaturated fatty acid, omega 6 linoleic acid, have not been established. In this cohort, substituting dietary linoleic acid in place of saturated fats increased the rates of death from all causes, coronary heart disease, and cardiovascular disease. An updated meta-analysis of linoleic acid intervention trials showed no evidence of cardiovascular benefit. These findings could have important implications for worldwide dietary advice to substitute omega 6 linoleic acid, or polyunsaturated fats in general, for saturated fats.
This article below discusses some of the issues with O6:O3 ratio and has a number of links to various studies:
http://chriskresser.com/how-too-much-om ... ng-us-sick
From studies I have read the primary issues lie in the structuring of cell membranes and the instability of PUFA's with their high rate of oxidation. Basically we only need very small amounts of these fatty acids, around 4% of total fat intake in roughly equal quantities, they perform specific signalling roles in cell membranes, as they compete for the same enzymatic machinery in the body when you ingest too much of them in an unbalanced ratio, then this is what the body gets to use, particularly if saturated fats are reduced as well. This basically results in leaky cells that require more maintenance and energy to maintain their integrity. It also means that the brain does not get access to it's DHA requirement because there is too much Omega 6 floating around in the system and the Omega 3 doesn't get processed. The excess intake then also puts a drain on the body's supply of anti oxidants in order to try and prevent them oxidising and causing systemic inflamation, as a side note arterial plaque contains no saturated fats and is primarily composed of oxidised PUFA's, this in itself suggests it may be a good idea to reduce PUFA intake.
The information is out there, but don't expect to get it in a concise single line conclusion in a study, that study is likely years away because the establishment and the powers that be are still deeply entrenched in the failed "Lipid Hypothesis" which says saturated fat (SFA's) causes heart disease and as there are a limited amount of choices we have for fat intake, there is a natural reluctance to suggest PUFA's might be worse than SFA's. According to lipid profiles our fatty acid intakes should be about 2% each of of O6 & O3 PUFA's, ideally from whole food sources, and the rest split evenly, say 48% of SFA's & 48% MUFA's, there is some flexability, but as long as intake is in that general area our bodies can manage the rest.
It also takes between 2-4 years for our bodies to balance lipid profiles once intake has been corrected, a lot of oxidised Omega 6 is stored in adipose tissue and the body needs time to dispose of it, this is another reason short term trials are a waste of time, it takes quite a few years to regain full health.
There are obviously other impacts on health through diet, environment & lifestyle but the PUFA story has been a bit of a sleeper and it's only now that the impacts of misguided healthe recommendations are coming to light.