Secondary Motor Symptoms of Parkinson's
Parkinson’s disease (PD) is a chronic disease that affects the neurological system, and it affects a person’s ability to move (motor symptoms) as well as other brain and body functions (non-motor symptoms). PD is characterized by four primary motor symptoms: tremor, rigidity, postural instability (impaired balance), and bradykinesia (slowing down and loss of spontaneous movement). In addition to these four classic symptoms, there are several secondary motor symptoms that people with PD may experience. Not every patient experiences all symptoms, and different people experience the disease in varying severities.1,2
The secondary motor symptoms associated with PD include:
- Freezing of gait or shuffling gait – the gait, or way of walking, may be affected by a temporary hesitation (freezing) or dragging of the feet (shuffling)
- Micrographia – abnormally small or cramped handwriting that shrinks as the condition progresses
- Unwanted accelerations – movements which are too quick, which may appear in movement or in speech
- Speech difficulty or changes in speech – including slurred speech or softness of voice
- Stooped posture – the body leans forward and the head may be slightly turned down
- Dystonia – prolonged muscle contractions and cramping that can cause twisting of body parts or repetitive movements
- Impaired fine motor dexterity – difficulty with precise hand and finger movement, such as in writing, sewing, or fastening buttons
- Poverty of movement – lack of natural, subtle movements like the decreased arm swing during walking
- Akathisia – restless movement, which may appear as being jumpy or fidgety
- Difficulty swallowing
- Sexual dysfunction – decreased sex drive, inability to orgasm, erectile dysfunction in men, decreased lubrication in women, or pain with intercourse in women2-4
Other symptoms of Parkinson’s disease
In addition to the motor symptoms, 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
Why does Parkinson’s disease cause motor symptoms?
While the exact disease process is not fully understood, scientists do know that PD causes damage to the nerves in the brain and in the body. Blobs or aggregates of a protein called alpha-synuclein are called Lewy bodies, and these can cause neurons not to function properly or die. Loss of dopamine-producing neurons in the substantia nigra pars compacta produces the characteristic motor symptoms, including slowing of movement, muscular rigidity, and resting tremor, that are generally used to clinically diagnose PD. However, these symptoms are only a subset of the assorted motor, cognitive, affective, autonomic and sensory impairments that result from the impaired function of neurons in different areas of the central and peripheral nervous systems in PD. While characterized as a movement disorder, PD can also be described as a multisystem neurodegenerative disorder, as it damages the neurons in multiple areas of the body.5
Treatment for motor symptoms of Parkinson’s disease
While there is no known cure for PD at this time, and there are not currently any treatments to slow or stop the natural progression of the disease, there are a number of treatments that can manage the motor symptoms.
Most patients with PD are started on medication to help manage their 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, including rigidity. 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.6
In addition to medication, physical therapy can help with muscle cramps, and regular exercise and stretching are beneficial to strengthen muscles and maintain flexibility. Trying to move throughout the day can reduce symptoms. Exercises such as yoga, tai chi and weight lifting have also been shown to help. The more high intensity the exercise is, the more beneficial it is at alleviating symptoms. Assistive devices such as walkers or canes can also be helpful.
For some people with PD whose symptoms are not adequately controlled with medication, surgery to perform deep brain stimulation may be an option. As with medication, surgery does not cure or change the course of the disease progression, but it may help with the symptoms of PD.3