One thing that struck me is that Zamboni's original tests weren't truly blinded. If an MS patient had an obvious physical problem, the doctors and techs would realize the person probably had MS. The article seems to confim this:
Zivadinov says that his study might have been “better blinded”, which might have removed some levels of subjectivity during ultrasound scanning. “All patients walked in [to the ultrasound test room] with a walking stick, so the technician wouldn't know which subjects had MS or other neurological disease”, says Zivadinov.
Also, some people have been arguing that the big difference in percentages between Zamboni and the Buffalo group was due to differences in ultrasound machines. But
Zamboni's team also used a more sensitive ultrasound machine, which might explain the much higher prevalence of CCSVI among patients with MS in their study, says Zivadinov. This, however, does not explain why Zamboni's more sensitive machine did not pick up any venous abnormalities in the control individuals, whereas the Buffalo team found that 22% of healthy control individuals had CCSVI.