Well u got the pic up......but I can not really give u much info from this...sorry....but I could not say if u have an obstruction...u need a CINE MRI for that...wish I were a Dr to tell u something more...
The picture shows an overcrowded posterior fossa, but according to the 'standards' it's not CM, so I doubt anyone will recognize it as chiari (I don't mean chiari experts) as the tonsils at exactly at the level of foramen magnum. Note the peg like tonsils.
Even this is an older MRI..I had one done in July 2011 and saw two neurologist who said nothing was wrong hmm I do see differences within my MRI opposed to other peoples but everyone different. No nuerologist have really compared my Meier together the old and new ones