Definition

Parkinson's disease (PD) is a progressive movement disorder that causes:

• Muscle rigidity
• Tremor at rest
• Slowing down of movements (bradykinesia)
• Difficulty moving and gait instability

Causes

Symptoms are caused by a loss of nerve cells in a part of the brain called the substantia nigra. Genetic, environmental, or a combination of both factors cause this loss. This loss decreases the amount of dopamine in the brain. Low dopamine results in PD symptoms. A small percentage of people with this condition have an early onset form caused by an inherited gene defect.

	Substantia Nigra—Yellow Section
	© 2008 Nucleus Medical Art, Inc.

Secondary parkinsonism is a condition with similar symptoms. But symptoms can be caused by several factors, including:

• Antipsychotic drugs, such as haloperidol (Haldol), fluphenazine (Prolixin), trifluoperazine (Stelazine), and chlorpromazine (Thorazine)
• Carbon monoxide poisoning
• Manganese poisoning
• Hydrocephalus
• Brain tumors
• Stroke
• Encephalitis
• Meningitis
• Intravenous drug abuse of MPTP (a type of neurotoxin)
• Reserpine
• Insecticide exposure
• Trauma
• AIDS

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition. Risk factors include:

• Age: 50 or older
• History of polio
• Gender: men (slightly more likely to develop PD)
• Family members with PD
• Nonsmokers
• Exposure to toxins, drugs, or conditions listed above

Symptoms

Symptoms of PD begin mildly and worsen over time.

Symptoms include:

• "Pill-rolling" tremor in the hands
• Tremors are present at rest, improve with movement, and are absent during sleep
• Stiffness and rigidity of muscles, usually beginning on one side of the body
• Difficulty and shuffling when walking
• Short steps
• Slowness of purposeful movements
• Trouble performing usual tasks, due to shaking in hands
• Trouble speaking
• Flat, monotonous voice
• Stuttering
• Shaky, spidery handwriting
• Poor balance
• Difficulty with rising from a sitting position
• “Freezing”
• Anxiety
• Seborrhea (a skin problem that causes a red rash and white scales)
• Loss of smell
• Tendency to fall
• Stooped posture
• Increasingly mask-like face, with little variation in expression
• Trouble chewing and swallowing
• Depression
• Dementia
• Difficulty thinking, problems with memory

Diagnosis

The doctor will ask about your symptoms and medical history, and perform a physical exam. There are no tests to definitively diagnose PD. The doctor will ask many questions to rule out other causes of your symptoms.

Tests to rule out other conditions may include:

• Blood tests
• Urine tests
• CT scan—a type of x-ray that uses a computer to make pictures of structures inside the head
• MRI scan—a test that uses magnetic waves to make pictures of structures inside the head
• PET scan—a scan that makes images that show the amount of activity in the brain

Treatment

Currently, there are no treatments to cure PD or proven treatments to slow or stop its progression. Some medications are used to improve symptoms. Over time, however, the side effects may become troublesome, and the medications may lose their effectiveness.

Medications

Medications include:

• Levodopa/carbidopa (Sinemet)
• Amantadine (Symmetrel)
• Anticholinergics: benztropine (Cogentin) and biperidin (Akineton)
• Selegiline (Eldepryl)
• Dopamine agonists: bromocriptine (Parlodel), pergolide (Permax), pramipexole (Mirapex), cabergoline (Dostinex), and ropinirole (Requip)
  • Pergolide (Permax) was withdrawn from the market in March 2007 due to the risk of serious heart valve damage; cabergoline (Dostinex) has also been associated with a similar risk. *
• Apomorphine (Apokyn)
• COMT inhibitors: entacapone (Comtan) and tolcapone (Tasmar)

Also, medications to treat depression or hallucinations associated with PD may be given. These may include selective serotonin reuptake inhibitors (SSRIs) and the antipsychotic clozapine. Because these medications can worsen other symptoms of the condition, you will need to be closely monitored

Surgery

Different brain operations are available, and many more are being researched including:

• Destroying certain areas of the brain (thalamotomy and pallidotomy)—to improve tremor when medication does not work
• Deep brain stimulation—implanting a device to stimulate certain parts of the brain to decrease tremor and rigidity
• Nerve-cell transplants (research only)—to increase amount of dopamine made in the brain

Physical Therapy

Physical therapy, exercise, and stretching can improve muscle tone, strength, and balance.

Psychological Support

Joining a support group with other people who are learning to live with the challenges of PD can be very helpful.

Prevention

There are no guidelines for preventing PD.

RESOURCES:

American Academy of Neurology
http://www.aan.com/

National Institute of Neurological Disorders and Stroke
http://www.ninds.nih.gov/

National Parkinson Foundation
http://www.parkinson.org/

Parkinson's Disease Foundation, Inc.
http://www.pdf.org/

CANADIAN RESOURCES:

Health Canada
http://www.hc-sc.gc.ca/index_e.html/

Parkinson Society
http://www.parkinson.ca/

References:

American Academy of Neurology. American Academy of Neurology website. Available at: http://www.aan.com/professionals/. Accessed June 13, 2008.

Frank S. Parkinson's disease. In: Gilman S, ed. MedLink Neurology. San Diego, CA: MedLink Corporation. Available at: http://www.medlink.com. Accessed May 12, 2008.

Goetz CG. Textbook of Clinical Neurology. Philadelphia, PA: WB Saunders Company; 1999.

Parkinson's disease. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php. Accessed May 12, 2008.

Parkinson's disease information page. National Institute of Neurological Disorders and Stroke website. Available at: http://www.ninds.nih.gov/disorders/parkinsons_disease/parkinsons_disease.htm. Updated April 10, 2008. Acessed June 13, 2008.

Rowland LP, Merritt HH. Merritt's Neurology. 11th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005.

Samii A, et al. Parkinson's disease. Lancet. 2004;363:1783-1793.

Samuels MA, Feske SK. Office Practice of Neurology. Philidelphia, PA: Churchill Livingstone; 2003.

Siderowf A, et al. Update on Parkinson's disease. Ann Intern Med. 2003;138:651-658.

* 4/10/2007 DynaMed's Systematic Literature Surveillance: US Food and Drug Administration. FDA announces voluntary withdrawal of Pergolide products [press release]. March 29, 2007. US Food and Drug Administration website. Available at: http://www.fda.gov/bbs/topics/NEWS/2007/NEW01596.html

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