Parksinson's Disease

Pathophysiology

Parkinson's disease belongs to a group of conditions called motor system disorders.

The disease is both chronic and progressive. It is not contagious nor is it usually inherited.
Parkinson's disease is the most common form of Parkinsonism, the name for a group of disorders with similar features. These disorders share the four primary symptoms described above, and all are the result of the loss of dopamine-producing brain cells. Parkinson's disease is also called primary parkinsonism or idiopathic Parkinson's disease.. In the other forms of Parkinsonism either the cause is known or suspected or the disorder occurs as a secondary effect of another, primary neurological disorder.

Parkinson's disease occurs when neurons, in the substantia nigra die or become impaired. Normally, these neurons produce dopamine which is a neurotransmitter between the substantia nigra and the corpus striatum, to produce smooth, purposeful muscle activity. Loss of dopamine causes the nerve cells of the striatum to fire out of control, leaving patients unable to direct or control their movements in a normal manner.

The cause of the destruction of these nerve cells is currently unknown but many researchers believe that a combination of four mechanisms - oxidative damage, environmental toxins, genetic predisposition, and accelerated aging - may be responsible.

Symptoms

The four primary symptoms are tremor or trembling in hands, arms, legs, jaw, and face; rigidity or stiffness of the limbs and trunk; bradykinesia or slowness of movement; and postural instability or impaired balance and coordination. Patients may have difficulty walking, talking, or completing other simple tasks.

Other symptoms of Parkinson's disease

Depression: This is a common problem and may appear early in the course of the disease, even before other symptoms are noticed. Depression may not be severe, but it may be intensified by the drugs used to treat other symptoms of Parkinson's disease.

Emotional changes: Some people with Parkinson's disease become fearful and insecure. Perhaps they fear they cannot cope with new situations. They may not want to travel, go to parties, or socialize with friends. Some lose their motivation and become dependent on family members. Others may become irritable or uncharacteristically pessimistic. Memory loss and slow thinking may occur, although the ability to reason remains intact. Whether people actually suffer dementia from Parkinson's disease is a controversial area still being studied.


Diagnosis

There are, as yet, no sophisticated blood or laboratory tests available to diagnose the disease. The physician observe the patient for some time until it is apparent that a tremor is consistently present and is joined by one or more of the other classic symptoms.

Treatment

Not all patients require drug treatment and medications are considered when the symptoms are sufficiently bothersome for the patient.

LevodopaThe gold standard of present therapy is the drug levodopa (also called L-dopa). L-Dopa (from the full name L-3,4-dihydroxyphenylalanine) is a simple chemical found naturally in plants and animals. Levodopa is the generic name used for this chemical when it is formulated for drug use in patients. Nerve cells can use levodopa to make dopamine and replenish the brain's dwindling supply. Dopamine itself cannot be given because it doesn't cross the blood-brain barrier. Usually, patients are given levodopa combined with carbidopa which delays the conversion of levodopa into dopamine until it reaches the brain, preventing or diminishing some of the side effects that often accompany levodopa therapy. Levodopa delays the onset of debilitating symptoms and allows the majority of Parkinsonian patients to extend the period of time in which they can lead relatively normal, productive lives

Side Effects of LevodopaThe most common side effects are nausea, vomiting, low blood pressure, involuntary movements, and restlessness..

Support Groups

One of the most demoralizing aspects of the disease is how completely the patient's world changes. The most basic daily routines may be affected - from socializing with friends and enjoying normal and congenial relationships with family members to earning a living and taking care of a home. Faced with a very different life, people need encouragement to remain as active and involved as possible.

Contributed by John Lee

Source: http://www.medicinenet.com/parkinsons_disease/article.htm