My husband had a cerebellar stroke in 2014. We don t know when exactly as it was diagnosed during an emergency visit for extreme lightheadness, nausea, etc. All tests have been done, cannot find any reason. He is athletic, 57 yrs. old and in excellent health. He seems to have intermittent bouts with lighheadness sometimes severe. We have been to the hospital many times in the last year as we worry these bouts are another stroke. Each time, ct scan reveals past strokes. Any idea what these bouts are caused by?