Parkinson's Disease (Parkinson Disease)

Paralysis agitans (1907, after St. Leger)[1]

Parkinson's disease is a form of neurological disorder characterized by gradual loss of those neurological functions that governs body movement. The disease is therefore also referred to as movement disorder.


Presentation

In the early stages of the disease, signs and symptoms are pretty less evident. However, as the disease progresses to more advance stages the following symptoms are prominent [7]:

  • Tremors characterized by shaking hands, fingers and legs.
  • Bradykinesia characterized by slowed movement making everyday simple tasks,difficult to achieve.
  • Muscle stiffness sets in as the disease advances.
  • Posture and balance of the individual get disrupted.
  • Individuals may experience difficulty in writing due to loss of motor movements.
  • Changes in the speech may occur.
  • Automatic movements such as blinking, swinging arms while walking and making gestures while talking are all lost.

Workup

So far no laboratory tests exist for diagnosing Parkinson's disease. A neurologist will diagnose the disease based on the past medial history of the affected individual followed by thorough analysis of the signs and symptoms. In addition, certain tests may also be required to rule out the possibility of any underlying disease condition. In order to arrive at an appropriate diagnosis, the neurologist will give medications meant for Parkinson's disease to the individual. If the individual benefits from the drug then the diagnosis is confirmed [8].

Treatment

Parkinson's disease cannot be cured; the symptoms can be effectively managed and progression of the condition slowed down with appropriate treatment methods. Medications form an important part of treatment regime. In more advanced stages, however surgery may be advised. The following are the various medications prescribed for treating Parkinson's disease.

  • Carbidopa-levodopa is one of the most effective medications for Parkinson disease. This is a natural chemical that gets converted to dopamine when it reaches the brain [9].
  • Medications containing dopamine antagonists are prescribed which unlike levodopa do not get converted to dopamine but mimic the effects of the brain chemical.
  • Monoamine oxidase B (MAO-B) inhibitors do not allow the breakdown of dopamine. However, this class of medication has various side effects when taken with other drugs.
  • Anticholinergics help in controlling the tremors; however are seldom prescribed due to associated side effects.
  • Amantadine is prescribed for short term relief from the symptoms. It is also given in association with levodopa to reduce dyskinesias that may accompany as a side effect of carbidopa-levodopa drug [10].

Prognosis

As the disease progresses, there is gradual loss of neurological functions in the affected individuals. Individuals who do not receive proper treatment often suffer from other secondary debilitating conditions. There is absolute loss of movement making the individual completely bed ridden for rest of the life. However, with introduction of newer generation medications, it has now been possible to effectively manage the symptoms and improve the quality of life [6].

Etiology

Parkinson disease occurs due to necrosis of certain nerve cells in the brain which are responsible for producing dopamine. The exact cause that triggers the development of such a type of movement disorder is yet to be known. However, interplay of several factors such as environment and genetic are known to play a role. Genetic factors attribute to 10% cases of Parkinson disease.

Genetic factors

Certain genes have been identified to play a major role in causation of Parkinson's disease. Individuals with family history of this disease are at an increased risk of contracting it as they age.

Environmental factors

Exposure to certain toxins can predispose an individual to develop Parkinson's disease [2].

Epidemiology

Parkinson disease is the second most common neurological disorder affecting about 7 million individuals across the globe. An estimated 1 million individuals of United States suffer from this neurodegenerative disorder [3]. Individuals aged 60 years and above fall easy prey to this disease. Men are 1.5 times more likely to contract Parkinson's disease, compared to women. Statistics have revealed that a small percentage of individuals (5 – 10%) between the age group of 20 – 50 years have been known to develop this kind of movement disorder [4].

Sex distribution
Age distribution

Pathophysiology

Parkinson's disease is a result of death of neurons in the brain. These are responsible for producing dopamine. Dopamine is a chemical messenger of the brain that transmits information to control the movements in various parts of the body [5]. The inability of the neurons to produce dopamine causes motor impairment which is the major cause of disability amongst the affected individuals. It has also been found that about 60 – 80% of necrosis of the nerve cells occurs even before the preliminary signs and symptoms of Parkinson's disease occur.

Prevention

Till date, no methods have been developed to prevent Parkinson's disease. Since the cause is unknown, ways to prevent the onset of the disease also remains a mystery. However, there have been some pieces of evidence suggesting the use of caffeine to help prevent Parkinson's disease.

Summary

Individuals over the age of 60 years are the most affected.The disease steadily causes disability greatly interfering with the individual’s ability to carry out daily functions. The preliminary stage of the disease may showcase little or no symptoms. Parkinson's disease cannot be cured. The symptoms can be effectively managed with appropriate medications. In some cases, surgical procedures may be required to improve the symptoms [1].

Patient Information

Definition

Parkinson's disease is a neurodegenerative disorder characterized by loss of neurological functions due to necrosis of the nerve cells in the brain. It is known to be the second most common neurological disorder after Alzheimer disease. Individuals above the age of 60 years are more prone to develop this condition. Parkinson's disease greatly affects the movement ability of the individuals and therefore the disease is also commonly referred to as movement disorder.

Cause

The exact factor that leads to development of Parkinson's disease is not clear. However certain genetic factors and exposure to environmental toxins is known to cause this type of neurological disorder.

Symptoms

In the initial stages, Parkinson's disease may show little or no signs at all. As the disease progresses to more advance stages, individuals experience tremors of the hands, fingers and legs. They also have difficulty in walking and their movements slow down to a great extent. Difficulty in talking is evident with slurred speech.

Diagnosis

No laboratory tests help in diagnosing the condition. A thorough examination of the signs and symptoms help in confirming Parkinson's disease.

Treatment

Medications form the basis of the treatment regime. Various classes of drugs are prescribed to keep the symptoms under control. Carbidopa-levodopa is the most effective drug for treating Parkinson's disease. It works by getting converted into dopamine once it reaches the brain.

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References

  1. Langston JW. The Parkinson's complex: parkinsonism is just the tip of the iceberg. Ann Neurol 2006; 59:591.
  2. Pezzoli G, Cereda E. Exposure to pesticides or solvents and risk of Parkinson disease. Neurology. May 28 2013;80(22):2035-41.
  3. Wirdefeldt K, Adami HO, Cole P, Trichopoulos D, Mandel J. Epidemiology and etiology of Parkinson's disease: a review of the evidence. Eur J Epidemiol. Jun 2011;26Suppl 1:S1-58.
  4. Van Den Eeden SK, Tanner CM, Bernstein AL, et al. Incidence of Parkinson's disease: variation by age, gender, and race/ethnicity. Am J Epidemiol 2003; 157:1015.
  5. Hornykiewicz O. The discovery of dopamine deficiency in the parkinsonian brain. J Neural TransmSuppl 2006; :9.
  6. Jeffrey S. Biomarkers for Parkinson's Diagnostic, Prognostic. Medscape [serial online]. Available at http://www.medscape.com/viewarticle/810262.
  7. Politis M, Wu K, Molloy S, et al. Parkinson's disease symptoms: the patient's perspective. MovDisord 2010; 25:1646.
  8. Tolosa E, Gaig C, Santamaría J, Compta Y. Diagnosis and the premotor phase of Parkinson disease.Neurology. Feb 17 2009;72(7 Suppl):S12-20.
  9. Stocchi F, Rascol O, Kieburtz K, et al. Initiating levodopa/carbidopa therapy with and without entacapone in early Parkinson disease: the STRIDE-PD study. Ann Neurol. Jul 2010;68(1):18-27.
  10. Weintraub D, Sohr M, Potenza MN, Siderowf AD, Stacy M, Voon V, et al. Amantadine use associated with impulse control disorders in Parkinson disease in cross-sectional study. Ann Neurol. Dec 2010;68(6):963-8.

Media References

  1. Paralysis agitans (1907, after St. Leger), PD-US

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