Secondary parkinsonism.

Although many disorders are included in secondary parkinsonism, the mechanisms underlying parkinsonism vary and have yet to be elucidated. Herein, we introduced a group of diseases included among the forms of secondary parkinsonism and provide overviews of clinically significant drug-induced parkinsonism (DIP), vascular parkinson- ism (VP), and idiopathic normal pressure hydrocephalus (iNPH) with a focus on pathophysiology and symptoms. Although DIP has the highest frequency among the forms of secondary parkinsonism, it is overlooked in many patients due to lack of knowledge about drugs by the prescribing physicians. Both VP and iNPH present with "lower body parkinsonism, " showing the characteristic gait disturbance. DIP and iNPH are treatable, highlighting the importance of early diagnosis and treatment intervention.