Nerve cells use a brain chemical called dopamine to help control muscle movement. Parkinson’s disease occurs when the nerve cells in the brain that make dopamine are slowly destroyed. Without dopamine, the nerve cells in that part of the brain cannot properly send messages, which leads to the loss of muscle function and gets worse with time. Exactly why these brain cells waste away is unknown.
Parkinson’s disease is a common neurodegenerative condition characterized by slowness of movement, resting tremor, and stiffness of muscles. Medications provide dramatic improvement in these symptoms, however over time, many patients develop motor fluctuation or disabling abnormal movements associated with the medications.
- Slowness of movement, or bradykinesia
- Muscle stiffness, or rigidity
- Stooped, shuffling gait
- Decreased arm swing when walking
- Lack of facial expression
- Slowed activities of daily living
- Impaired balance
- Diminished sense of smell
- Low voice volume
- Sleep disturbance
- Urinary frequency/urgency
- Male erectile dysfunction
Although no treatment has been definitively shown to stop or slow disease progression, there is effective treatment for the symptoms of the disease. Medical and surgical treatments are available. Other approaches include physical therapy and exercise.
The following classes of drugs are used to treat the motor symptoms of Parkinson's disease:
- Levodopa-carbidopa (Sinemet)
- MAO inhibitors: selegiline (Eldepryl, Zelapar), rasagiline (Azilect)
- COMT inhibitors: entacapone (Comtan), tolcapone (Tasmar)
- Dopamine agonists: pramipexole (Mirapex), ropinirole (Requip), cabergoline (not approved in the U.S.), apomorphine (Apokryn), and others
- Anticholinergics: trihexyphenidyl (Artane), benztropine (Cogentin)
- Amantadine (Symmetrel)
Surgical treatments, such as deep brain stimulation (DBS), are used for more advanced patients whose symptoms can no longer be adequately managed with medications.
Deep brain stimulation uses implanted electrodes to stimulate a specific target in the brain. The electrical stimulation interferes with the abnormal activity, creating the same effect as a lesion.