Generally medical strains would be high in CBD, but not necessarily THC, but I don't really know about MS specifically. A good choice for a high CDB medical strain would be Harlequin.
[h=1]Harlequin[/h]
Classification: Sativa (75%)/Indica (25%)
Growing Environment: Indoor Recommended
Flowering Time: 60 - 70 days
THC Content: Low
CBD Content: High
Garden Ability: Beginner to Intermediate
Medicinal Uses: Pain relief, anti-inflammatory, anxiety
Cannabissearch.com Buzz Rating: The taste is ever-so-sweet with definite fruitiness, with the aroma being thick, sweet and hash-like.
Harlequin is preceded by a Thai cannabis strain, a Swiss one, and a Columbian Gold marijuana strain. While Harlequin is notably low in THC content (lab testing in California showed around 7%), it is considerably high in CBD (usually showing results between 5% and 9%). Cannabidiol content this high in strains throughout dispensaries is considered somewhat rare in recent time, making this unique strain sought after for it's pain relieving qualities and noticeable cerebral effects.
Comparitively, this amazing hybrid begins her flowering cycle early. Dime-sized buds are oftentimes visible after just 2 weeks into Harlequin producing the first buds. Additionally, growers should take caution in the last week or two before they harvest this plant. The flowering tops become so heavy and buds so tri-chrome-covered that the colas will require extra support to keep from collapsing under all this added weight. An added frustration - but one that is well worth the wait - is that Harlequin usually takes between 2 and 3 weeks to finish the curing process.
Harlequin is not for those smokers who are just looking to "catch a buzz," due to the low THC content, however medicinally speaking, this strain is great for patients looking for chronic pain relief or who enjoy meditating, because of the amount of CBD present in the cannabis. Harlequin is one of those strains that, when grown properly, will come out amazing, but when grown improperly, has a tendency to be an abomination.