The motor symptoms of Parkinson’s disease refer to those that affect the body’s movement.
Motor symptoms are grouped into primary motor symptoms and secondary motor symptoms. Primary motor symptoms are important for the diagnosis of the disease. In addition, there are non-motor symptoms associated with the disease.
Primary motor symptoms
Primary motor symptoms include resting tremor, bradykinesia (slowness of movement), rigidity, and postural instability.
In the early stages of the disease, about 70 percent of patients experience a slight tremor in the fingers, hand, or foot on one side of the body, or occasionally in the jaw or face.
The tremor consists of a shaking or oscillating movement, and usually appears when a person’s muscles are at rest or relaxed, hence the term “resting tremor.” Sometimes a hand tremor can be stopped by keeping the hand in motion or in a flexed grip. The tremor may get worse with stress or excitement and often spreads to the other side of the body as the disease progresses, but usually remains most apparent on the initially affected side.
Bradykinesia is a defining feature of Parkinson’s disease that involves a general reduction of spontaneous movement, which can give the appearance of abnormal stillness and a decrease in facial expressiveness. Due to bradykinesia, a person with Parkinson’s disease may have difficulties executing repetitive movements and performing everyday tasks, such as buttoning a shirt or brushing their teeth. People who experience bradykinesia may walk with short, shuffling steps. The reduction in movement caused by bradykinesia can affect a person’s speech as the disease progresses.
Rigidity includes stiffness or inflexibility of the muscles of the neck, shoulders, trunk, and limbs. It causes the affected muscles to remain stiff and not relaxed, decreasing the range of motions. Rigidity can be uncomfortable or even painful. A person with rigidity and bradykinesia cannot swing their arms while walking.
Another important symptom of Parkinson’s disease is postural instability or impaired balance, which is caused by the loss of reflexes that keep people in an upright posture. Some patients develop a dangerous tendency to sway backward when rising from a chair, standing, or turning. This problem is called retropulsion and may result in a backward fall.
Secondary motor symptoms
In addition to the cardinal signs of Parkinson’s disease, there are many other motor symptoms associated with the disease.
An important sign of Parkinson’s disease is freezing of gait, when patients temporarily feel as if their feet are glued to the floor and hesitate before stepping forward. After the first step, people usually resume their normal stride. Freezing may occur in specific situations such as when a patient is starting to walk, crossing a doorway, or approaching a chair. Freezing is serious because it may increase a person’s risk of falling forward.
Micrographia refers to the shrinkage in Parkinson’s patients’ handwriting. This happens as a result of bradykinesia, which causes difficulty with repetitive actions.
The face of an individual with Parkinson’s disease may appear less expressive due to decreaed facial movements. The flexed posture of the disease may result from a combination of rigidity and bradykinesia.
Some people with Parkinson’s disease experience unwanted rapid movements. These involuntary accelerations are troublesome, particularly during speech and movement. People with excessively fast speech (or tachyphemia) produce a rapid stammering that is hard to understand. Those who experience an uncontrollable acceleration in gait (or festination) are at an increased risk for falls.
Some patients may experience additional secondary motor symptoms including:
- Dystonia (painful muscle cramps)
- Stooped posture (a tendency to lean forward)
- Impaired fine motor dexterity and motor coordination
- Impaired gross motor coordination
- Reduced movement (decreased arm swing)
- Akathisia (tendency to keep moving)
- Speech problems (such as soft voice or slurred speech)
- Difficulty swallowing
- Sexual dysfunction
- Reduced swallowing movements (causing drooling and excess saliva)
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