There is no cure for Parkinson's disease. Many patients are only mildly affected and need no treatment for several years after the initial diagnosis. When symptoms grow severe, doctors usually prescribe levodopa (L-dopa), which helps replace the brain's dopamine. Sometimes doctors prescribe other drugs that affect dopamine levels in the brain.
Usually, patients are given levodopa combined with carbidopa. Carbidopa delays the conversion of levodopa into dopamine until it reaches the brain. Nerve cells can use levodopa to make dopamine and replenish the brain's dwindling supply. Although levodopa helps at least three-quarters of Parkinsonian cases, not all symptoms respond equally to the drug. Bradykinesia and rigidity respond best, while tremor may be only marginally reduced. Problems with balance and other symptoms may not be alleviated at all. Anticholinergics may help control tremor and rigidity.
Other drugs, such as pramipexole and ropinirole, mimic the role of dopamine in the brain, causing the neurons to react as they would to dopamine. An antiviral drug, amantadine, also appears to reduce symptoms. In May 2006, the FDA approved rasagiline to be used along with levodopa for patients with advanced Parkinson's disease or as a single-drug treatment for early Parkinson's disease.
In some cases, surgery may be appropriate if the disease doesn't respond to drugs. In patients who are very severely affected, a kind of brain surgery known as pallidotomy has reportedly been effective in reducing symptoms. A therapy called deep brain stimulation (DBS) has now been approved by the FDA. In DBS, electrodes are implanted into the brain and connected to a small electrical device called a pulse generator that can be externally programmed. DBS can reduce the need for levodopa and related drugs, which in turn decreases the involuntary movements called dyskinesias that are a common side effect of levodopa. It also helps to alleviate fluctuations of symptoms and to reduce tremors, slowness of movements, and gait problems. DBS requires careful programming of the stimulator device in order to work correctly.