Parkinson’s disease is a neurological condition that is associated with difficulty in coordinating movements. This disease usually develops gradually, often presenting with a barely noticeable tremor (shaking) in just one hand. While tremor may be the most well-known sign of Parkinson’s disease, the disorder also commonly causes a slowing or freezing of movement in addition to stiffness (rigidity).
Many symptoms of Parkinson’s disease result from the lack of a chemical messenger called Dopamine in the brain. This occurs when the specific brain cells that produce Dopamine die or become impaired. The precise etiology of Parkinson’s disease is unknown at this time. The symptoms of Parkinson’s disease include tremor, which usually begins as a back-and-forth rubbing of your thumb and forefinger, known as pill-rolling. Many patients with Parkinson’s disease, however, do not experience a significant tremor. Slowed movement (bradykinesia) is also common in Parkinson’s disease and reduces the ability to initiate voluntary movement. This may make even the simplest tasks become difficult and time-consuming. Trying to walk with Parkinson’s disease becomes more difficult, as patients experience shortened, shuffling steps. At times, patients may experience freezing, making it hard to take a first step. Rigidity is another common symptom of Parkinson’s disease, which can become severe, limiting the range of movements and causing pain. Patients with Parkinson’s disease often develop soft, hesitating speech. Automatic movements such as blinking, smiling and swinging the arms may also be impaired in Parkinson’s disease. Many patients develop a fixed, staring expression with unblinking eyes. In the later stages of Parkinson’s disease, some patients may develop problems with memory and mental clarity (dementia). Associated depression may also occur in 20% of patients.
A diagnosis of Parkinson’s disease is usually made clinically by the observation of symptoms by a trained neurologist. Recently, the FDA has approved a diagnostic test for Parkinson’s disease. The DaTscan is a nuclear medicine test, which can show a loss of dopamine neurons in the substantia nigra. It may be useful in distinguishing Parkinson’s disease form essential tremor.
The initial treatment of Parkinson’s disease involves medications that can help manage the symptoms. Most of these medications work by increasing the level of Dopamine in the brain. The most effective Parkinson’s drug is Levodopa, which is a natural substance that passes into the brain and eventually converts itself to Dopamine inside the brain. Other medications include Dopamine agonists, which mimic the effects of Dopamine in the brain and cause neurons to react as though Dopamine is present. This class of pill includes the trade names Mirapex and Requip.
Other medications involve anticholinergics such as Cogentin and antivirals such as Amantadine.
Deep brain stimulation is the most common surgical procedure used to treat Parkinson’s disease. It involves implanting an electrode deep within the parts of the brain that control movement. The stimulation is delivered through the electrode by a pacemaker-like device that is implanted under the skin in the upper chest. Deep brain stimulation is most often used for people who have advanced Parkinson’s disease and who have begun to respond less predictably with medications. More recently, the trend by movement disorder neurologists is to recommend DBS earlier in the course of the disease. The two most common basal ganglia targets for DBS are the Subthalamic Nucleus (STN) and the Globus Pallidus Internus (GPi).
For many patients with Parkinson’s disease, deep brain stimulation is a life changing procedure, that can markedly increase the ability for patients to perform simple daily tasks.