The Differences Between Parkinsonian Syndrome and Essential Tremor
Parkinsonian syndromes (PS) and essential tremor (ET) are two types of movement disorders, diseases where people have difficulty with movement. PS and ET are progressive diseases, which means that they can get worse over time. PS and ET movement disorders are sometimes described as "hypokinetic" (meaning "too little movement") when a person experiences slowness and rigidity, or "hyperkinetic" (meaning "too much movement") when they experience tremor or shaking. Even though these diseases cannot yet be cured, their symptoms can be treated. And the sooner they are diagnosed, the sooner you or your loved one will be able to begin treatment and learn more about how the disease and symptoms may change over time. One of the tools involved in diagnosis is testing that can help your doctor decide if your symptoms are caused by PS or ET.
The differences between PS and ET movement disorders
The following shows the most common symptoms of PS and ET movement disorders. It does not represent a complete list of symptoms.
Parkinsonian Syndrome Movement Disorders
- Parkinson's Disease
- Description: The most common parkinsonian movement disorder that may cause tremor at rest, rigidity, slow movement, loss of control over movement, stooped posture, and freezing.
- Common symptoms: Tremor, stiffness/rigidity, balance/postural problems, slow gait, vocal symptoms, sleep problems, depression, dementia
- Progressive Supranuclear Palsy
- Description: A movement disorder characterized by unsteady walking, early frequent falls, and freezing. The person walks with feet wide apart, an erect posture, and unbent knees. Some people with this disorder move and think very slowly.
- Common symptoms: stiffness/rigidity, slow gait, vocal symptoms, sleep problems, depression, dementia
- Multiple System Atrophy, parkinsonian type
- Description: A disorder that affects 4 parts of the nervous system: basal ganglia (parkinsonism), cerebellum (balance problems), motor neurons (spasticity and weakness), and problems with function (impotence, noisy breathing or snoring, low blood pressure when standing up, urinary problems, dizziness, cold pale hands).
- Common symptoms: Stiffness/rigidity, balance/postural problems
Essential Tremor Movement Disorder
- Description: Also known as familial tremor, benign essential tremor, or hereditary tremor, ET is a progressive neurological condition that causes a rhythmic trembling of the hands, typically upon voluntary movement, head, voice, legs, or trunk. It is not caused by loss of dopamine.
- Common symptoms: Tremor upon voluntary movement
What is PS?
Parkinsonian syndromes may occur when the brain does not produce enough dopamine, a brain chemical it needs to perform certain functions. This affects the brain's ability to control movement and other muscle functions. The most common PS is Parkinson's disease, which affects approximately 1.5 million people in the United States. Some symptoms of PS may include:
- Tremor (shaking) in one or more body parts when trying to remain still
- Postural instability (balance problems)
- Rigidity or stiffness
- Slowed movement (bradykinesia) and a shuffling walk
- Freezing and inability to move
- Small, cramped handwriting
- Facial mask (stiff facial expression)
- Vocal symptoms (muffled speech, soft voice)
- Dementia, or memory loss and confusion
- Gait disturbance, or problems with walking
- Difficulty sleeping
In addition, some people also experience loss of smell and constipation.
What is ET?
Essential tremor is the most common movement disorder. It affects as much as 4% of the U.S. population over the age of 65.
With ET, the hands, head, voice, and sometimes the legs and trunk of the body may shake. Unlike PS, tremor occurs when people are actively moving, not staying still.
Essential tremor tends to run in families. People with so-called "familial" ET usually get it earlier in life than those with "non-familial" or "sporadic" ET, but this is hard to determine, since there have not been many studies of families who do and don't have the condition. It is thought that environmental factors may have something to do with non-familial ET.
Diagnosing PS and ET
One important difference between PS and ET is whether or not there is a decline in the parts of the brain (the substantia nigra) that make dopamine (degeneration of the dopaminergic system). Doctors diagnose a movement disorder by observing physical symptoms, which are similar in both conditions. However, relying on clinical signs and symptoms alone for an accurate diagnosis may be difficult.
There is a test that can help show whether there is a loss of dopamine receptors in the brain. This can help doctors determine if symptoms are the result of PS or ET.
Next: Learn About Diagnosis