I am a little confused about Medial Medullary Syndrome (MMS). I had 2 questions on one practice test about occlusion of the anterior spinal artery (ASA) on the same practice test on USMLERx, with very different results. In MMS, there is occlusion of the ASA, which causes the symptoms associated with this type of stroke. However, if the ASA is occluded, is the collateral circulation to the rest of the spinal cord (all the way up to the caudal brainstem!) from the Artery of Adamkiewicz the reason you don't get problems a quadraplegic paralysis starting from say C1? Any help is appreciated!