Parkinson's disease is a progressive disorder of the nervous system that affects movement. Parkinson's disease (PD) can simply be defined as a chronic and progressive movement disorder, meaning that symptoms continue and worsen over time. It develops gradually, sometimes starting with a barely noticeable tremor in just one hand. But while a tremor may be the most well-known sign of Parkinson's disease, the disorder also commonly causes stiffness or slowing of movement.
In the early stages of Parkinson's disease, your face may show little or no expression, or your arms may not swing when you walk. Your speech may become soft or slurred. Parkinson's disease symptoms worsen as your condition progresses over time.
Although Parkinson's disease can't be cured, medications may markedly improve your symptoms. In occasional cases, your doctor may suggest surgery to regulate certain regions of your brain and improve your 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 Parkinson’s 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.
tremor of the hands, arms, legs, jaw and face
bradykinesia or slowness of movement
rigidity or stiffness of the limbs and trunk
postural instability or impaired balance and coordination
Making an accurate diagnosis of Parkinson’s particularly in its early stages is difficult, but a skilled practitioner can come to a reasoned conclusion that it is Parkinson’s disease. You may have experienced this frustration. Perhaps it took years for you to receive a diagnosis. Perhaps you have been diagnosed, but with Parkinsonism, not Parkinson's, and are confused about the implications. Because there are no definitive diagnostic tests for Parkinson’s, the diagnosis can sometimes be unclear.
The term “parkinsonism” is a generic descriptive term that refers to the whole category of neurological diseases that causes slowness of movement. The category includes the classic form of Parkinson’s disease, many atypical variants, sometimes called “Parkinson’s Plus Syndromes,” and any other brain disease that resembles Parkinson’s, such as hydrocephalus or drug-induced parkinsonism.
In all cases of parkinsonism, no matter the cause, there is a disturbance in the dopamine systems of the basal ganglia — a part of the brain that controls movement. In all cases, this dopamine deficiency leads to the characteristic combination of tremor, slowness, rigidity and postural instability.
How is Parkinson’s Diagnosed?
Often, the diagnosis of Parkinson’s is first made by an internist or family physician. Many people seek an additional opinion from a neurologist with experience and specific training in the assessment and treatment of Parkinson’s disease referred to as a movement disorder specialist.
To diagnose Parkinson’s, the physician takes a careful neurological history and performs an examination. There are no standard diagnostic tests for Parkinson’s, so the diagnosis rests on the clinical information provided by the person with Parkinson’s and the findings of the neurological exam.
The doctor looks to see if your expression is animated.
Your arms are observed for tremor, which is present either when they are at rest, or extended.
Is there stiffness in your limbs or neck?
Can you rise from a chair easily?
Do you walk normally or with short steps, and do your arms swing symmetrically? The doctor will pull you backwards.
How quickly are you able to regain your balance?
The main role of any additional testing is to exclude other diseases that imitate Parkinson’s disease, such as stroke or hydrocephalus. Very mild cases of PD can be difficult to confirm, even by an experienced neurologist. This is in part because there are many neurological conditions that mimic the appearance of Parkinson’s.
A person’s good response to levodopa (which temporarily restores dopamine action in the brain) may support the diagnosis. But this is not relevant if your doctor thinks you do not need any medication at this time. If you are in doubt of your diagnosis or if you need further information, you may want to seek a second opinion.
DaTscan for Parkinson's
What is the role of DaTscan for Parkinson's disease? During a diagnosis you may hear of this imaging test or be asked to undergo one.
While DaTscanscannot diagnose Parkinson's disease, the imaging technology may provide beneficial insights to help a doctor confirm a PD diagnosis in the early stages of the disease.
Young Onset Parkinson's
What is young-onset Parkinson’s disease? Most people with Parkinson’s begin to develop movement symptoms after the age of 60. When a person younger than 50 years old is diagnosed with PD, it is called young-onset PD. (Some doctors may refer to young-onset when diagnosed under the age of 40.)
Young-onset PD is unusual, affecting about five to 10 percent of people with PD. Although their symptoms are similar to those of older people with PD, people with young-onset PD often face different financial, family and employment concerns.
Symptoms of PD
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 non-motor 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.
By definition, Parkinson’s is a progressive disease. Although some people with Parkinson’s only have symptoms on one side of the body for many years, eventually the symptoms begin on the other side. Symptoms on the other side of the body often do not become as severe as symptoms on the initial side.
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 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 is postural 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, the neurologist 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
Most people with Parkinson’s experience non-motor 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 non-motor symptoms may precede motor symptoms — and a Parkinson’s diagnosis — by years. The most recognizable early symptoms include:
Loss of sense of smell
REM behaviour 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 Non-motor 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 behaviours