In 11 patients, loss of postural reflexes was the initial and predominant manifestation of parkinsonism. None of these patients responded to standard anticholinergic medication. All 11 responded dramatically to amantadine or levodopa. It is important to recognize that parkinsonian deficit can manifest itself solely or predominantly as falling. Such patients usually respond well to amantadine or levodopa.
(JAMA 230:1555-1557, 1974)