Parkinson's disease (PD) is a disorder of the central nervous system that affects movement, muscle control and balance. Parkinson's disease is both chronic, meaning it persists over a long period of time, and progressive, meaning its symptoms grow worse over time. It is not contagious.
Parkinson's disease occurs when nerve cells, or neurons, in an area of the midbrain known as the substantia nigra die or become impaired. Normally, these neurons produce an important brain chemical known as dopamine. Dopamine is a chemical messenger responsible for transmitting signals from the brain to our extremities to produce coordinated movements. Loss of dopamine results in abnormal nerve firing patterns within the brain that cause impaired movement.
People with PD also have loss of the nerve endings that produce the neurotransmitter norepinephrine. Norepinephrine, which is closely related to dopamine, is the main chemical messenger of the sympathetic nervous system, the part of the nervous system that controls many automatic functions of the body, such as pulse and blood pressure. The loss of norepinephrine might help explain several of the non-motor features seen in PD, including fatigue and abnormalities of blood pressure regulation.
The four main symptoms of Parkinson's disease include tremor, rigidity, bradykinesia (slowness of movement), and postural instability (impaired balance). These symptoms usually begin gradually and worsen with time. As they become more pronounced, patients may have difficulty walking, talking, or completing other simple tasks. Not everyone with one or more of these symptoms has PD, as the symptoms sometimes appear in other diseases as well.
Diagnosis of PD is based on medical history and neurological examination. Brain scans or laboratory tests may be required in order to rule out other diseases. However, CT and MRI brain scans of people with PD usually appear normal. Since many other diseases have similar features but require different treatments, making a precise diagnosis as soon as possible is essential so that patients can receive the proper treatment.
Although Parkinson's disease can't be cured, medications or surgery can sometimes provide dramatic relief from the symptoms. Conservative treatment measures such as medications, physical therapy, occupational therapy, and speech therapy will be ordered before surgery is considered as an option.
If conservative treatment measures are not successful in improving the symptoms of PD, surgical treatment may be considered. The earliest types of surgery for PD involved selectively destroying specific parts of the brain that contribute to the symptoms of the disease. Because these procedures cause permanent destruction of brain tissue, they have largely been replaced by Deep Brain Stimulation surgery for treatment of PD which does not destroy any brain tissue.
Deep brain stimulation, or DBS, uses tiny electrodes surgically implanted into part of the brain. The electrodes are connected by a wire under the skin to a small electrical device called a pulse generator that is implanted in the chest beneath the collarbone. The pulse generator and electrodes painlessly stimulate the brain in a way that helps to stop many of the symptoms of PD. DBS is stereotactic surgery, meaning it uses a 3D coordinate mapping system to locate tiny areas in our bodies in order to perform surgery accurately.