Unfound Causes

I've heard that a lot of people don't find the cause of their pulsatile tinnitus, does that mean that there probably isn't a serious problem causing it?

 

Why would there be a correlation between the inability to find the cause of some symptom and the severity of the cause?

 

@GregCA, I would think that a major clog in blood vessels or tumor would be easier to detect. Also, I wasn't saying there was necessarily a correlation, there are probably less serious causes that are easily found. I might be wrong, which is why I was asking the question in the first place.