MRA Show Damage From Ergot? If so, Treatable?

Doctor:  I know that you can only go by what's on the report: my much beloved 78 yr old mother has progressive weakness in left arm and leg over past year.  Her neurologist suspects that it may be due to ergot poisoning as her Primary Care allowed her to progress up to 1, 2 and even 3 Cafergot suppositories EVERY SINGLE DAY for two years for chronic migraine headaches and she'd been taking at last 5 or more per week for at least 20 years before. Neuro ordered MRA of head & neck w & w/o contrast, here's report - does it sound like ergot poisoning and, either way, is this treatable/reversable at all.  (She's been on Depakot for 1 month now):
*MRA Neck W/ 7 W/O Contrast  History: Leftsided Heakness & Increased Tone
FINDINGS: The origins of the grest vessals show no areas of stenoses.  There is, however, stenosis at the origins of the right vetebral artery.  Otherwise, the left veterbral artery, internal & external arteries,  & the carotib bulb/bifurcation shows no areas of stenoses.  The arteries are of the usual caliber.
IMPRESSION:  Moderate stenosis at the origin of the right vetebral artery.  Otherwise unremarkeble MRA of the neck.
*MRA Brain W/O Contrast
FINDINGS: There is a mild diffuse irregularly of the A-2 segment of the left anterior cerebral artery. Otherwise, the vertebral, basilar, and carotid arteries and their branches are of usual course and caliper.  No areas of aneurysmal dilatation or vascular malformation is seen.
IMPRESSION: Mild diffuse irregularity and narrowing of the A-2 segment of the left anterior cerebral artery.
THANK YOU VERY MUCH!

[CCF-Neuro-M.D.-PW]

I cannot provide a formal report on the MRI scan without seeing it so this advice is very limited and is for educational use

Ergot is a vasoconstrictor and has been associated with strokes in certain susceptible individuals. However, taking ergot for a long time does not necessarily exclude other causes for a stroke, which are common in the elderly such as hardening of the arteries or atherosclerosis. Once stopping ergot any vsocontriction should resolve. Stenosis of the vertbral artery means that there is some atherosclerosis there, and there is an increased risk for stroke which should be assessed by a neurologist - she may need daily aspirin or other blood thinners, or other stroke risk prevention.

You do not mention if there is a stroke within the brain on MRI, but the presention of left arm/leg weakness could be anything from the spinal cord to the right side of the brain, so a stroke should not necessarily be assumed either. YOur neurologist shoul dbe able to sort through the issues

Good luck