Motor Symptoms of Parkinson's
Parkinson’s disease (PD) is a progressive neurological disorder that affects approximately 1 million Americans. Motor symptoms of PD, those that affect motor functioning, or movement, are characteristic of the disease’s effects on the body and include:
PD is highly variable, and not every patient with PD will experience all the symptoms. Different patients will have different combinations of symptoms as well as severity of symptoms, and each case of PD progresses on an individual level.2
Other symptoms of Parkinson’s disease
In addition to these primary motor symptoms, there are secondary motor symptoms that can occur in people with PD, including a shuffling gait (rhythm of walking), micrographia (abnormally small or cramped handwriting), a mask-like expression, or speech difficulties. There are many non-motor symptoms that people with PD experience, such as depression, difficulty swallowing or chewing, urinary problems, constipation, skin problems, sleep problems, pain, and cognitive problems, such as memory problems or slow thinking. 1,2
Several other neurological conditions mimic PD, which may make diagnosis difficult. Diagnosis is made by a neurologist and is generally based on clinical assessment of the main motor symptoms, a gradual progression of symptoms, and the relief of motor symptoms with levodopa therapy.3 Treatments are more successful the earlier the symptoms are diagnosed. Therefore, it is important to see a movement disorder specialist as soon as PD is suspected.
How Parkinson’s disease causes primary motor symptoms
PD damages the neurons (nerve cells) in the brain, especially an area of the brain called the substantia nigra pars compacta. The neurons in the substantia nigra produce dopamine, a neurotransmitter (chemical messenger) that transmits signals from the substantia nigra to other parts of the brain to produce smooth, purposeful movement. When the neurons in the substantia nigra are damaged in large numbers, the loss of dopamine causes impaired movement and the motor symptoms of PD: tremor, rigidity, impaired balance, and loss of spontaneous movement. Research has shown that people with PD have lost 60-80% or more of the neurons that produce dopamine by the time symptoms appear.1,4,5
Treatment for primary motor symptoms in Parkinson’s disease
Although there are currently no medications that can cure or slow the progression of PD, there are several treatments that can help relieve symptoms, including the primary motor symptoms of PD. Treatment approaches include medications, surgery (deep brain stimulation), and complementary or alternative medicine.
Several medications are available that can help relieve the primary motor symptoms. Initial therapy is usually levodopa (administered with carbidopa), dopamine agonists, and/or monoamine oxidase-B (MAO-B) inhibitors. The combination of levodopa and carbidopa is the most effective treatment available for the management of motor symptoms of PD. However, it can cause a side effect known as dyskinesia, which are abnormal involuntary movements. Dopamine agonists are less effective on the motor symptoms of PD but have a lower rate of causing dyskinesia, although they have other side effects. MAO-B inhibitors are less effective than levodopa or dopamine agonists, however they have fewer side effects. Choice of therapy should be customized to the individual patient with an understanding of the risks and benefits of each class of medication.3