Parkinson’s disease (PD) is a chronic and progressive movement disorder, meaning that symptoms continue and worsen over time. Nearly one million people in the US are living with Parkinson’s disease. The cause is unknown, and although there is presently no cure, there are treatment options such as medication and surgery to manage its symptoms.
Parkinson’s involves the malfunction and death of vital nerve cells in the brain, called neurons. Parkinson’s primarily affects neurons in an area of the brain called the substantia nigra. Some of these dying neurons produce dopamine, a chemical that sends messages to the part of the brain that controls movement and coordination. As PD progresses, the amount of dopamine produced in the brain decreases, leaving a person unable to control movement normally.
The specific group of symptoms that an individual experiences varies from person to person. Primary motor signs of Parkinson’s disease include the following.
1.tremor of the hands, arms, legs, jaw and face
2.bradykinesia or slowness of movement
3.rigidity or stiffness of the limbs and trunk
4.postural instability or impaired balance and coordination
Scientists are also exploring the idea that loss of cells in other areas of the brain and body contribute to Parkinson’s. For example, researchers have discovered that the hallmark sign of Parkinson’s disease — clumps of a protein alpha-synuclein, which are also called Lewy Bodies — are found not only in the mid-brain but also in the brain stem and the olfactory bulb.
These areas of the brain correlate to nonmotor functions such as sense of smell and sleep regulation. The presence of Lewy bodies in these areas could explain the nonmotor symptoms experienced by some people with PD before any motor sign of the disease appears. The intestines also have dopamine cells that degenerate in Parkinson’s, and this may be important in the gastrointestinal symptoms that are part of the disease.
The diagnosis of PD depends upon the presence of one or more of the four most common motor symptoms of the disease. In addition, there are other secondary and nonmotor symptoms that affect many people and are increasingly recognized by doctors as important to treating Parkinson’s.
Each person with Parkinson’s will experience symptoms differently. For example, many people experience tremor as their primary symptom, while others may not have tremors, but may have problems with balance. Also, for some people the disease progresses quickly, and in others it does not.
PRIMARY MOTOR SYMPTOMS
Almost 200 years after Parkinson’s was first discovered and after many new discoveries about the biology of the disease, a diagnosis still depends on identifying the core features — tremor, slowness and stiffness — described by James Parkinson. The diagnosis of Parkinson’s does not come from a test, but instead requires a careful medical history and a physical examination to detect the cardinal signs of the disease, including:
Resting Tremor: In the early stages of the disease, about 70 percent of people experience a slight tremor in the hand or foot on one side of the body, or less commonly in the jaw or face. A typical onset is tremor in one finger. The tremor consists of a shaking or oscillating movement, and usually appears when a person’s muscles are relaxed, or at rest, hence the term “resting tremor.” The affected body part trembles when it is not performing an action. Typically, the fingers or hand will tremble when folded in the lap, or when the arm is held loosely at the side, i.e., when the limb is at rest. The tremor usually ceases when a person begins an action. Some people with PD have noticed that they can stop a hand tremor by keeping the hand in motion or in a flexed grip. The tremor of PD can be exacerbated by stress or excitement, sometimes attracting unwanted notice. The tremor often spreads to the other side of the body as the disease progresses, but usually remains most apparent on the initially affected side. Although tremor is the most noticeable outward sign of the disease, not all people with PD will develop tremor.
Bradykinesia:Bradykinesia means “slow movement.” A defining feature of Parkinson’s, bradykinesia also describes a general reduction of spontaneous movement, which can give the appearance of abnormal stillness and a decrease in facial expressivity. Bradykinesia causes difficulty with repetitive movements, such as finger tapping. Due to bradykinesia, a person with Parkinson’s may have difficulty performing everyday functions, such as buttoning a shirt, cutting food or brushing his or her teeth. People who experience bradykinesia may walk with short, shuffling steps. The reduction in movement and the limited range of movement caused by bradykinesia can affect a person’s speech, which may become quieter and less distinct as Parkinson’s progresses.
Rigidity: Rigidity causes stiffness and inflexibility of the limbs, neck and trunk. Muscles normally stretch when they move, and then relax when they are at rest. In Parkinson’s rigidity, the muscle tone of an affected limb is always stiff and does not relax, sometimes contributing to a decreased range of motion. People with PD most commonly experience tightness of the neck, shoulder and leg. A person with rigidity and bradykinesia tends to not swing his or her arms when walking. Rigidity can be uncomfortable or even painful.
Postural Instability:One of the most important signs of Parkinson’s ispostural instability, a tendency to be unstable when standing upright. A person with postural instability has lost some of the reflexes needed for maintaining an upright posture, and may topple backwards if jostled even slightly. Some develop a dangerous tendency to sway backwards when rising from a chair, standing or turning. This problem is called retropulsion and may result in a backwards fall. People with balance problems may have particular difficulty when pivoting or making turns or quick movements. Doctors test postural stability by using the “pull test.” During this test, theneurologist gives a moderately forceful backwards tug on the standing individual and observes how well the person recovers. The normal response is a quick backwards step to prevent a fall; but many people with Parkinson’s are unable to recover, and would tumble backwards if the neurologist were not right there to catch him or her.
SECONDARY MOTOR SYMPTOMS
In addition to the cardinal signs of Parkinson’s, there are many other motor symptoms associated with the disease.
Freezing: Freezing of gait is an important sign of PD that is not explained by rigidity or bradykinesia. People who experience freezing will normally hesitate before stepping forward. They feel as if their feet are glued to the floor. Often, freezing is temporary, and a person can enter a normal stride once he or she gets past the first step. Freezing can occur in very specific situations, such as when starting to walk, when pivoting, when crossing a threshold or doorway, and when approaching a chair. For reasons unknown, freezing rarely happens on stairs. Various types of cues, such as an exaggerated first step, can help with freezing. Some individuals have severe freezing, in which they simply cannot take a step. Freezing is a potentially serious problem in Parkinson’s disease, as it may increase a person’s risk of falling forward.
Micrographia:This term is the name for a shrinkage in handwriting that progresses the more a person with Parkinson’s writes. This occurs as a result of bradykinesia, which causes difficulty with repetitive actions.
Mask-like Expression: This expression, found in Parkinson’s, meaning a person’s face may appear less expressive than usual, can occur because of decreased unconscious facial movements. The flexed posture of PD may result from a combination of rigidity and bradykinesia.
Unwanted Accelerations: It is worth noting that some people with Parkinson’s experience movements that are too quick, not too slow. These unwanted accelerations are especially troublesome in speech and movement. People with excessively fast speech, tachyphemia, produce a rapid stammering that is hard to understand. Those who experience festination, an uncontrollable acceleration in gait, may be at increased risk for falls.
Additional secondary motor symptoms include those below, but not all people with Parkinson’s will experience all of these.
*Stooped posture, a tendency to lean forward
*Impaired fine motor dexterity and motor coordination
*Impaired gross motor coordination
*Poverty of movement (decreased arm swing)
*Speech problems, such as softness of voice or slurred speech caused by lack of muscle control
*Drooling and excess saliva resulting from reduced swallowing movements
NON MOTOR SYMPTOMS
Most people with Parkinson’s experience nonmotor symptoms, those that do not involve movement, coordination, physical tasks or mobility. While a person’s family and friends may not be able to see them, these “invisible” symptoms can actually be more troublesome for some people than the motor impairments of PD.
Many researchers believe that nonmotor symptoms may precede motor symptoms — and a Parkinson’s diagnosis — by years. The most recognizable early symptoms include:
*Loss of sense of smell, constipation
*REM behavior disorder (a sleep disorder)
*Orthostatic hypotension (low blood pressure when standing up).
If a person has one or more of these symptoms, it does not necessarily mean that individual will develop Parkinson’s, but these markers are helping scientists to better understand the disease process.
Other Nonmotor Symptoms
Some of these important and distressing symptoms include:
*Weight loss or gain
*Vision and dental problems
*Fatigue and loss of energy
*Fear and anxiety
*Cognitive issues, such as memory difficulties, slowed thinking, confusion and in some cases, dementia
*Medication side effects, such as impulsive behaviors