symptoms of parkinsons disease : symptoms of parkinsons disease

Definition

Parkinson's disease (PD) is a progressive movement disorder marked by tremors, rigidity, slow movements (bradykinesia), and postural instability. It occurs when, for unknown reasons, cells in one of the movement-control centers of the brain begin to die.
Description

PD affects approximately 500,000 people in the United States, both men and women, with as many as 50,000 new cases each year. Usually beginning in a person's late 50s or early 60s, it causes a progressive decline in movement control, affecting the ability to control initiation, speed, and smoothness of motion. Symptoms of PD are seen in up to 15% of those between the ages 65-74, and almost 30% of those between the ages of 75 and 84.
Causes & symptoms

The immediate cause of PD is the degeneration of brain cells in the area known as the substantia nigra, one of the movement control centers of the brain. Damage to this area leads to the cluster of symptoms known as parkinsonism. In PD, degenerating brain cells contain Lewy bodies, which help identify the disease. The cell death leading to parkinsonism may be caused by a number of conditions, including infection, trauma, and poisoning. Some drugs given for psychosis, such as haloperidol (Haldol) or chlorpromazine (thorazine), may cause parkinsonism. When no cause for nigral cell degeneration can be found, the disorder is called idiopathic parkinsonism, or Parkinson's disease. Parkinsonism may be seen in other degenerative conditions, known as the parkinsonism plus syndromes, such as progressive supranuclear palsy.

The substantia nigra, or black substance, is one of the principal movement control centers in the brain. By releasing the neurotransmitter known as dopamine, it helps to refine movement patterns throughout the body. The dopamine released by nerve cells of the substantia nigra stimulates another brain region, the corpus striatum. Without enough dopamine, the corpus striatum cannot control its targets, and so on down the line. Ultimately, the movement patterns of walking, writing, reaching for objects, and other basic programs cannot operate properly, and the symptoms of parkinsonism are the result.

Much research has gone into identifying the cause of PD, but as of July 2000, no clear culprit has been found. Both genetic and environmental factors are suspected. In addition to these causes, there are some known toxins that can cause parkinsonism, most notoriously a chemical called MPTP, found as an impurity in some illegal drugs. Parkinsonian symptoms appear within hours of ingestion, and are permanent. MPTP may exert its effects through generation of toxic molecular fragments called free radicals, and reducing free radicals has been a target of several experimental treatments for PD using antioxidants.

It is possible that early exposure to some as-yet-unidentified environmental toxin or virus leads to undetected nigral cell death, and that PD then becomes manifest as normal age-related decline brings the number of functioning nigral cells below the threshold needed for normal movement. It is also possible that, for genetic reasons, some people are simply born with fewer cells in their substantia nigra than others, and they develop PD as a consequence of normal decline. As of early 2000, however, no gene or toxin had been identified to explain the large number of cases of Parkinson's disease seen each year.

The identifying symptoms of PD include:

* Tremors, usually beginning in the hands, often occurring on one side before the other. The classic tremor of PD is called a pill-rolling tremor, because the movement resembles rolling a pill between the thumb and forefinger. This tremor occurs at a frequency of about three per second.
* Slow movements (bradykinesia) occur, which may involve slowing down or stopping in the middle of familiar tasks such as walking, eating, or shaving. This may include freezing in place during movements (akinesia).
* Muscle rigidity or stiffness, occurring with jerky movements replacing smooth motion.
* Postural instability or balance difficulty occurs. This may lead to a rapid, shuffling gait (festination) to prevent falling.
* In most cases, there is a masked face, with little facial expression and decreased eye-blinking.

In addition, a wide range of other symptoms may often be seen, some beginning earlier than others:

* depression
* speech changes, including rapid speech without inflection changes
* problems with sleep, including restlessness and nightmares
* emotional changes, including fear, irritability, and insecurity
* incontinence
* constipation
* handwriting changes, with letters becoming smaller across the page (micrographia)
* progressive problems with intellectual function (dementia).

Diagnosis

The diagnosis of Parkinson's disease involves a careful medical history and a neurological exam to look for characteristic symptoms. There are no definitive tests for PD, although a variety of lab tests may be done to rule out other causes of symptoms, especially if only some of the identifying symptoms are present. Tests for other causes of parkinsonism may include brain scans, blood tests, lumbar puncture, and x rays.
Encyclopedia of Alternative Medicine
by Paula Ford-Martin