~||{ National Parkinson Foundation }||~ ~||{ A World Wide Organization }||~
Is Everything that Trembles Parkinson Disease?
By Abraham Lieberman, MD, Medical Director of the National Parkinson
Foundation, Professor of Neurology at the University of Miami, Miami, FL
Introduction
A frequently asked question is "Is every tremor Parkinson disease?"
Essential tremor, not Parkinson disease, is the most common cause of
tremor. Essential tremor affects approximately 10,000,000 Americans, 10X as
many people as Parkinson disease. Essential tremor is often called benign
essential tremor, because it usually doesn't result in disability. Most
essential tremor patients are able to cope. Essential tremor is sometimes
called familial tremor, or hereditary tremor, or heredo-familial tremor,
because in approximately 50% of patients there is a family history of tremor.
Essential tremor is sometimes called senile or senescent tremor because it
usually occurs in senior citizens. Senile or senescent refers to the age at
which essential tremor occurs, not to the patient's mental capacity.
Because of the misleading association of the terms senile or senescent
tremor with senility or mental decline, the term senile or senescent tremor
isn't used.
Description
Essential tremor is characterized by involuntary rhythmical trembling or
oscillation of a body part -- usually the hands. The trembling usually
begins on both sides symmetrically, unlike the trembling of PD, which
begins on one side. Essential tremor may begin insidiously with the patient
unaware of (or in denial of) the trembling until it is pointed out.
Essential tremor usually begins in the second, third, fourth, or fifth
finger -- where it is apt to go unnoticed. This is unlike the trembling of
Parkinson disease which usually begins in the thumb and is more apt to be
noticed. The trembling in ET may, for years, remain unchanged in amplitude,
frequency, and distribution. Or the trembling may change in amplitude and
distribution. The changes are not rapid or striking.
The trembling in essential tremor may, in some people, affect the head, the
voice (as the vocal cords or tongue tremble), the legs, or the trunk. In
some patients trembling may begin in the head, the voice, or the tongue.
The trembling in essential tremor rarely begins in the legs. Trembling that
begins in an arm and a leg on the same side of the body, or in the jaw, is
more likely to be Parkinson disease.
In most people with essential tremor, the trembling worsens (or first
becomes visible) when the person voluntarily maintains his/her hands in a
fixed position as in holding his/her hands stretched in front of him. This
type of trembling is called a postural tremor.
In some people with essential tremor, the trembling worsens (or first
becomes visible) when the person voluntarily moves his/her hands, as in
performing an action such as bringing a glass of water to his/her lips,
tying his/her shoes, or threading a needle. This type of trembling is
called an action tremor. Most people with essential tremor have both
postural and action trembling.
Diagnosis
The following are useful in diagnosing essential tremor and excluding other
causes of trembling.
A postural or action trembling that starts in both hands simultaneously.
This is unlike Parkinson disease which is characterized by trembling that
begins in one hand and is present when the hand is at rest, and the muscles
relaxed. This is called a rest tremor.
Postural or action trembling present in both hands for at least two years.
Several conditions -- including caffeine or nicotine use or withdrawal,
alcohol abuse or withdrawal, lithium toxicity, electrolyte imbalance,
calcium deficiency or excess, and thyroid disease -- can result in
trembling. This type of trembling is usually temporary and disappears when
the underlying condition is corrected. Persistent trembling for at least
two years, in the absence of an underlying condition such as described
above, increases the possibility of essential tremor.
Postural or action trembling present in both hands for at least two years
in the absence of symptoms of Parkinson disease. Approximately 20% of
people with Parkinson begin with postural and/or action trembling. However,
within two years other Parkinson symptoms appear.
Head trembling.
Head trembling (as distinct from jaw trembling) associated with postural
and/or action trembling of the hands suggests essential tremor.
A strong family history, defined as: several members of the same generation
who have similar trembling, such as brothers and sisters or first cousins;
several members of one or more older generations who have similar
trembling, such as mother or father, aunts or uncles, grandmothers and
grandfathers, great-aunts and great-uncles; several members of the younger
generation who have similar trembling, such as children, nephews, and nieces.
The trembling of essential tremor may be temporarily relieved by alcohol.
Alcohol, however, is not a treatment for essential tremor. Over time,
increasingly higher doses of alcohol are required to relieve essential
tremor, and eventually alcohol fails to relieve it. The trembling of
essential tremor may be relieved by primidone (Mysoline). Primidone
(Mysoline) doesn't relieve the trembling of Parkinson disease. The
trembling of essential tremor may be relieved by propranolol (Inderal).
Propranolol (Inderal), however, may also relieve, temporarily, the
trembling of PD.
Prevalence
The prevalence of essential tremor increases with age. A study that surveys
people in a retirement community will come to a different conclusion than
one that surveys people in a college town. A study that surveys people
attending a specialty clinic (one that attracts patients with tremor) will
come to a different conclusion from one that surveys people in a general
medical clinic.
Among people of all ages, the prevalence of essential tremor varies from
4,000 to 40,000 people per 1,000,000 of population. Among people of age 60+
years, the prevalence of essential tremor varies from 13,000 to 50,000
people per 1,000,000 of population. Essential tremor affects at least 10
million Americans, 3.7% of the population. Essential tremor is 10 times
more frequent than Parkinson disease. Although almost all people with
Parkinson disease see a physician, less than 1% of all people with
essential tremor see a physician. This reflects the benign nature of
essential tremor. Essential tremor affects men and women equally. Parkinson
disease affects men more than women: 55 men for every 45 women. Essential
tremor, like Parkinson disease, can begin in adolescence.
Progression
In most people with essential tremor the trembling increases as time
passes. And a few people with essential tremor become disabled. The
disability results solely from the trembling. This is unlike Parkinson
disease where the disability results from the slowness of movement rather
than the trembling. Some people with essential tremor may have difficulty
doing everyday tasks such as handling small objects, tools, or utensils.
And some people with essential tremor have have difficulty writing,
drinking water from a cup or glass, feeding themselves, applying makeup,
shaving, or dressing.
Anxiety or stress may temporarily increase the trembling in essential
tremor and Parkinson disease.
Cause
In most people with essential tremor, the trembling is inherited. But how
an inherited defect results in trembling is unknown. Examination, after
death, of the brains of people with essential tremor is normal. It is been
proposed that abnormalities, below the level of visibility, in specific
brain structures -- the olives, the cerebellum, the thalamus -- result in
these structures acting as oscillators, setting up self-propagating
currents, resulting in trembling.
Parkinson disease Parkinson disease is an insidiously progressive disease.
There are 1.2 million people with Parkinson disease in America: 3,500
people with Parkinson disease for each 1,000,000 Americans. The typical
onset is age 60 years. Parkinson disease affects 1% of all people over age
60 years, 2% of all people over age 70 years. But, Parkinson disease is not
just a disease of seniors: 15% of Parkinson patients are 50 years or less.
Parkinson disease is characterized by 4 main symptoms:
(1) Rigidity or stiffness of one or more limbs. A stiffness like arthritis.
(2) Tremor of one or more limbs. The tremor is more prominent in the hands,
is present when the hands are relaxed, or at rest and is asymmetrical. In
30% of people with Parkinson there is no tremor.
(3) Bradykinesia, or slowness of movement of the limbs and body. Rigidity,
tremor, and slowness result, primarily, from a loss of dopamine in a region
of the brain called the striatum. Dopamine is a chemical which facilitates
the flow of impulses from nerve cells.
(4) Postural Instability results from impairment of postural reflexes, the
reflexes which allow people to adjust to abrupt changes in position. If you
trip and start falling, and if you're postural reflexes are normal, you're
able to rapidly and without thinking adjust your body and limbs to stop
falling. In Parkinson disease, your postural reflexes are lost and if you
trip, you're unable to stop falling.
How is Essential Tremor Diagnosed?
Essential tremor is diagnosed by a physician after taking a history and
performing an examination. If you tremble, have not seen a physician, and
wonder whether you have essential tremor you can complete the Tremor
Questionnaire. The questionnaire is not a substitute for a visit to your
physician.
