Most studies indicate that marijuana can precipitate a stroke, but I did find a few indicating its use as a therapeutic agent. You may wish to print these out and show them to your doctor.

A preliminary controlled study to determine whether whole-plant cannabis extracts can improve intractable neurogenic symptoms -- Wade et al. 17 (1): 21 -- Clinical Rehabilitation

http://www.drugpolicy.org/docUploads...herapeutic.pdf

http://63.240.200.111/pages/pdfs/dat...2/15402-03.pdf

Chronic smoking has been shown to decrease blood flow to the posterior cerebellum, even after 24 hours of abstention. If your damage is there, it's possible that smoking might clear the blood in that area (or other areas). The cerebellum, in general, controls motor function. It also controls one's sense of the passage of time.