Parkinson’s Disease – revised last 11/15/17
Parkinson’s disease was first described in 1817 by a London physician, James Parkinson. He described the hallmarks of the condition which is tremor, rigidity, bradykinesia, and gait dysfunction.
The disease is due to degeneration of neurons in the substantia niagra and in the 1960’s it was discovered that dopamine was depleted in the disease. Therefore, levodopa, a precursor to dopamine was developed as medication to improve the symptoms. The Hollywood film, Awakenings, starring Robin Williams, depicts the early use of levodopa to treat patients with a rare form of parkinson’s disease related to an epidemic of encephalitis.
Parkinson’s disease is one of the most common movement disorders. The average age of onset is about 60 years old and age is the one clear risk factor. Five to ten percent of patients have early onset Parkinson’s disease which is onset before age 50. A subset of patients have Parkinson’s disease due to some medication, drug, or chemical expose and a subset of patients have Parkinson’s disease due to a genetic components but the vast majority of cases are idiopathic meaning that there is no clear underlying cause.
There are several other conditions with similar physical exam features such as tremor, ridgidity, bradykinesia, and gait dysfunction. These features are referred to as parkinsonism which means some physical exam features seen in Parkinson’s disease but not necessarily Parkinson’s disease. Causes of parkinsonism other than Parkinson’s disease could include some other rare movement disorders referred to as Parkinson’s-Plus syndromes, Lewy Body dementia, or vascular parkinsonism.
Parkinson’s disease is a complex neurologic condition with manifestations other than the motor symptoms of tremor, rigidity, bradykinesia, and gait dysfunction. There can also be presence of autonomic dysfunction, mild cognitive impairment, depression and mood changes, disruption of normal sleep cycles, and difficulty with swallowing, chewing, and talking.
Diagnosis of Parkinson’s disease is made by detailed history and physical exam by a neurologist. No specific blood test or scan can clearly diagnose Parkinson’s disease. A trial of levodopa or other dopamine stimulating medication and therapeutic response also aids diagnosis.
For many patients, symptoms can be very well controlled for a long time with medications but regular follow up with a physician is needed for proper adjustment of medication.
By Vaibhav Shah, M.D.