“World renowned movement disorder specialist?”

My brother's neurologist diagnosed him with Parkinsonian Syndrome recently (probably vascular parkinsonian syndrome). I recommended that we find a "world-renown" Movement Disorder Specialist to tweak the diagnosis. He gave us a name and that MD retired in 2020. How does one go about finding such an individual? I have a list of about 20 MDSs from various places, i.e, Columbia-Presbyterian, Neuroscience Center of NJ, Rutgers-Robert Wood Johnson, and NJ Brain&Spine Movement Disorder Center. Trying to tease out the right person is daunting. Do you have any suggestions on how to search for the best doctor? We have spent a year and a half going to specialists (ENT, psychoneurologist, Vestibular PT, Audiologist, Geriatrician, neurologists, psychologist) and need a better way to get to the right one. His PCP has not been very helpful in this regard. His most aggravating symptom is dizziness (not vertigo) 24/7 that came on suddenly. He did not tolerate several anti-depressants or anti-anxiety agents.