Parkinson’s disease is a common neurologic disorder. It affects people of all ages and ethnic backgrounds and is seen in countries all around the world. Parkinson’s disease mostly begins between ages 55-60, although the majority of patients are over 65. Early onset Parkinson’s disease is now more widely recognized. Approximately ten percent of Parkinson patients are under the age of 50 (juvenile onset.) It is estimated that 1 million Americans are affected, with 50,000 new cases diagnosed annually. It affects men slightly more frequently than women. Modern therapy has provided excellent treatment and control of many of the symptoms of Parkinson’s disease, but it still remains a progressive neurodegenerative disorder.
Essay on the Shaking Palsy by James Parkinson, 1817
Historical Background
Parkinson’s disease has been referred to in history as far back as the ancient Egyptians. Hieroglyphic writings make reference to the symptoms of the disease. The references to Parkinson’s disease throughout historical literature include the Bible, writings of Galen-the-Great, a Greek physician of the second century and in Shakespeare’s works. In 1817 a British surgeon, James Parkinson, wrote an essay on The Shaking Palsy. In this paper he described the primary clinical symptoms of six patients affected with the disease. In the later 1800′s, this clinical syndrome of tremor, rigidity and slowness of movements (bradykinesia) came to bear Dr. Parkinson’s name.
Cause
The underlying disease process for Parkinson’s disease was discovered in the 1950′s. It was found that a specific area of the brain known as the substantia nigra was affected. The substantia nigra is a dark pigmented area located in the brainstem. It contains specialized nerve cells (neurons) that produce a neurotransmitter, dopamine. Dopamine is responsible for enabling the brain to generate signals for smooth, well-regulated motor (muscle) function. In patients with Parkinson’s disease, the dopamine producing neurons slowly die off. This results in a dopamine shortage in the brain. Patients who develop symptoms of Parkinson’s disease have already lost 80 percent of the dopamine producing neurons. Despite extensive clinical research, the cause for the loss of these dopamine-containing neurons in the substantia nigra remains a medical mystery.
Diagnosis
The clinical diagnosis of Parkinson’s disease is based on patient symptoms and findings on a neurological examination. There are no specific CT/MRI brain scan abnormalities or blood tests that confirm the diagnosis of Parkinson’s disease. A physician may order certain tests to exclude other problems, but the diagnosis of Parkinson’s disease is based on detailed clinical history and a physical exam. There are several neurologic diseases that mimic Parkinson’s disease. These syndromes have some of the clinical features of Parkinson’s disease. They are not, however, due to the dying off of nerve cells in the substantia nigra or due to dopamine deficiency. These syndromes are classified as atypical Parkinson’s disease or Parkinson Plus syndromes. Common among these syndromes are progressive supranuclear palsy, Wilson’s disease and cortical basal ganglionic degeneration (CBGD). Patients affected with one of these diseases frequently do not respond to the medications used to treat Parkinson’s disease. All of these neurological syndromes, including Parkinson’s disease, are in the family of neurodegenerative disorders. They are inexorably progressive – usually over a period of five to twenty years.