 These dopamine cells are especially vulnerable to damage, and a variety of insults, including encephalitis (as depicted in the book and movie "Awakenings"), repeated sports-related concussions, and some forms of chemical poisoning such as MPTP, can lead to substantial cell loss, producing a parkinsonian syndrome that is similar in its main features to Parkinson's disease.Most cases of Parkinson's disease, however, are idiopathic, meaning that the cause of cell death cannot be identified.The most widely used treatment for parkinsonism is administration of L-DOPA, the metabolic precursor for dopamine.