Parkinson’s Disease–An Introduction Chandra Shekhar Rawat and Sanjay Pandey Abstract Parkinson’s disease is the common neurodegenerative disorder that presents in a heterogeneous manner in terms of age at onset, natural history, clin- ical signs, genetic makeup, rate of disease progression, and response to treatment. Diagnosis of Parkinson’s disease relies on a good history with an inquiry about the sequence of emergence of symptoms and recognition of characteristic clin- ical features such as bradykinesia, rigidity, typical rest and reemergent tremor, and postural instability. These symptoms can also result from other neurodegenerative disorders as well as secondary to medications, metabolic causes, toxin exposures and all should be excluded in cases of suspicion, and historical review. It is necessary to recognize the non-motor features which may precede the motor manifestations such as olfactory dysfunction, constipation, rapid eye movement behaviour disorders that help in making an early diagnosis. Treatment of Parkinson’s disease requires an individualized approach based on clinical findings and complications. It involves pharmacologic approaches and surgical options such as deep brain stimulation. Keywords Parkinson’s disease · Substantia nigra · Alpha-synuclein · Lewy bodies · Deep brain stimulation 1 History The history of Parkinson’s disease (PD) can be traced back to 1817 when James Parkinson (1775–1824) published a monograph “an Essay on the Shaking Palsy”. He was a general medical practitioner who lived and worked in Shoreditch, as a British apothecary. Being a highly astute observer, James Parkinson described a disease of insidious onset and progressive disabling course [1]. He described rest tremor, flexed posture, and festination, whereas descriptions about rigidity or bradykinesia were not C. S. Rawat · S. Pandey (B ) Department of Neurology, Govind Ballabh Pant Postgraduate Institute of Medical Education and Research, New Delhi 110002, India e-mail: sanjaysgpgi2002@yahoo.co.in © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2022 S. P. Arjunan et al. (eds.), Techniques for Assessment of Parkinsonism for Diagnosis and Rehabilitation, Series in BioEngineering, https://doi.org/10.1007/978-981-16-3056-9_1 1