ABSTRACT
INTRODUCTION AND HISTORY Parkinson’s disease (PD) is a neurodegenerative disorder characterized by the cardinal motor manifestations of bradykinesia/akinesia, rigidity, resting tremor, and postural instability, although nonmotor features play an important role as well, including cognitive, psychiatric, and autonomic features (1). Pathologically, there is a loss of nigrostriatal neurons in the substantia nigra pars compacta (SNpc), which is believed to represent a middle stage of the degenerative process that starts in the lower brainstem and olfactory nuclei and ascends throughout the cortex (2). Neurochemically, the key feature relating to current therapeutics and nigral cell death is a loss of dopamine (3).
