Introduction
Parkinson’s disease was first described in 1817 by James Parkinson; it is a progressive neuro-degenerative disorder characterized by slowing, the reduced amplitude of movements both emotional and voluntary (bradykinesia), muscle rigidity, and tremors. It is the commonest neurodegenerative disorder, second to Alzheimer’s disease, and affects nearly 1: 1000 in the general population and the rate rises to 1% above 65 years of age. It is more common in males (males to females ratio is 3:2) (Lang, 2007).
Pathology of Parkinson’s disease
The etiology of Parkinson’s disease is a combination of biological, environmental, and less clearly understood genetic factors (Lang, 2007).
Disturbances in dopaminergic neurotransmission
The substantia nigra is a grey matter mass (neurons) that is responsible for muscle tone and contributes to maintaining posture. Neurons passing from the substantia nigra to the corpus striatum are responsible for commencement and carrying out voluntary movements, with dopamine as their neurotransmitter. The dopaminergic deficiency theory of Parkinson’s disease explains both motor and psychological manifestations of the disease. The theory assumes motor features of the disease are the result of neuron death in the zona compacta of substantia nigra. Dopamine neurons loss in the zona reticulate (ventral part of substantia nigra) is responsible for thought, motivation, and mood disorders of Parkinson’s disease (Moore and colleagues, 2005).
Biological factors
First are cell death (apoptosis) and the role of α synuclein, although research suggests parkin, ubiquitin, and α synuclein proteins interact in the normal brain, yet, dopamine-rich nerve cells produce α synuclein. High levels of α synuclein are essential to developing inherited Parkinson’s disease as this protein’s functions are to maintain neural membrane stability and help the neurons to keep their function after a minor change. The other two proteins have a role in helping the natural process of self-destruction of α synuclein; thus preventing its accumulation and becoming toxic to dopamine (Recchia and colleagues (2004).
Second is the formation of Lewy bodies, which are the main pathological characteristic features of the disease, which are eosinophilic circular bodies, surrounded by a corona found in neuronal cytoplasm. It is not clear if these bodies are the result of the building up of α synuclein or they are responsible for cell death (Loutharius and Brundin, 2002). Some Parkinson’s disease patients show low levels of complex I (NADH-quinone oxidoreductase) enzyme system the mitochondria need to eliminate the free radicals. Therefore, some researchers suggested low levels of complex I make the neurons more susceptible to free radicals (oxidants) hazardous effect and cause cell damage (Loutharius and Brundin, 2002).
Environmental factors
It is hypothesized that environmental toxins whether infective (similar to encephalitis in flu epidemics), or chemicals (insecticides, ortriggerdes) triggers the production of excessive free radicals. It is argued that these factors do not initiate cell damage but have a role in the progression of nerve cells’ damage (Lang, 2007).
Genetic factors
Twins and familial studies suggest an important genetic background for early-onset Parkinson’s disease (before 50 years). The genetic abnormality is either in certain genes or in genetic locations, where defective PARK1 and PARK 5 genes lead to an autosomal dominant inheritance. PARK1 gene encodes α synuclein and gene defects lead to abnormal accumulation of α synuclein, PARK5 encodes ubiquitin needed to prevent α synuclein accumulation. PARK2 gene encodes parkin, and gene defects lead to an autosomal recessive form of the disease. The genetic background for late-onset Parkinson’s disease is less clear, and research suggests defects in PARK10 gene controlling biochemical processing of α synuclein (Mahlon and Juncos, 2004).
Diagnosis of Parkinson’s disease
Motor features of Parkinson’s disease
The presenting symptom is usually tremors (although 15% he f patient may never experience tremors). Parkinson’s tremors are characteristically resting tremors with a frequency of 4 to 6 cycles per second, and subside when moving the limb to reemerge after the limb takes a new position. Other characteristic features are rigidity secondary to increased muscle tone, when tremors superimpose, rigidity is characteristically cogwheel, and otherwise, it is lead-pipe rigidity. Bradykinesia is a movement disturbance taking the form of a slow interrupted movement with reduced amplitude and easy fatigue.
Slow monotonous speech (hypophonia) and micrographia (small handwriting) are other forms of bradykinesia, and lack of change of facial expressions. Postural disturbances are a flexion posture of the trunk and limbs (stooped), and postural instability with the imbalance and a greater possibility to fall. Gait is characteristically a slow shuffling gait (Habermann and Ghosh, 2008).
Nonmotor features of Parkinson’s disease
The main cognitive deficit in Parkinson’s disease is dementia, which is a direct sequel of the disease, and according to the American Psychological Association, should be accompanied by one other cognitive deficit (as language, visuospatial..) with unimpaired consciousness. Parkinson’s dementia impairs the patient’s quality of life and adds to the caregivers’ burden, what adds to the problem is that dementia indirectly adds to the motor features because, with its onset, medications for tremors should be stopped. Second are behavioral and psychological symptoms which include psychosis, anxiety, and depression. Sleep disorders in the form of restless leg disorders and rapid eye movement behavioral disorders, besides anosmia and disturbances of the autonomic nervous system (Samuel and others, 2006).
Treatment of Parkinson’s disease
Pharmacological treatment
Since the disease is slowly progressive, initiation of treatment depends on the patient’s preferences and the extent symptoms bother the patient or when disability becomes clear. The choices for pharmacological therapy of the motor symptoms are levodopa, dopaminergic drugs, anticholinergics or selective monoamine oxidase inhibitors (MAO B). Causes of levodopa treatment failure are usually preventable and include inadequate doses or duration of therapy, and drug interaction (with risperidone for schizophrenia and metoclopramide as an antiemetic). A trial of levodopa is the first line of pharmacologic therapy for three months gradually titrating the dose up to 1000 mg/day or till side effects appear.
Dopamine agonists are the first alternative to the failure of levodopa to control motor symptoms; they have the advantage of having the lesser risk of bradykinesia and motor fluctuation during the first few years of treatment. They should be stopped when dementia appears for fear of hallucinations. Other medications are ineffective in controlling motor symptoms if used alone; therefore they are usually combined with any of the first line medications. However, anticholinergics dementia and old age over 70 years are known contraindications (Nutt and Wooten, 2005).
Nutt and Wooten (2005, p.1025) stated that surgical treatment in the form of sub thalamic deep brain stimulation can improve all features of Parkinson’s disease.
Non pharmacological therapy
Support and patient education are essential at the time of diagnosis, of importance is to tell patients the disease is slowly progressive, the rate of progression differs from one patient to another, and there are many approaches to minimize the symptoms. Nursing care is important in palliative treatment when the disease is established. At this stage, cognitive deficits, mood and psychological disorders are the main issues a nurse has to deal with (Lee and others, 1994).
Bunting-Perry (2006, pp. 106-113) stated that based on WHO redefinition of palliative care and the advocacy of the Center to Advance Palliative Care, the term palliative care can be applied to moderate and advanced Parkinson’s disease cases. In these cases, motor symptoms become uncontrolled with pharmacological therapy, and non motor symptoms although receiving little attention in the clinical setting yet, represent a disability and a burden to the caregiver.
The Parkinson’s disease model of nursing care uses the palliative care guidelines to enable the neuroscience nurse planning an individually designed care for Parkinson’s disease patients along the course of the disease. Neuroscience nurse can support patients by identifying the main treatable symptoms and provide reassurance about untreatable ones. Besides, a neuroscience nurse can transfer experiences to the patient’s family through understanding the principles of palliative care thus help in improving the patient’s quality of life.
Prognosis of Parkinson’s disease
The disease inevitably progresses over many years; both rate and course of progress, and response to treatment vary from one patient to another. However, most patients experience increasing motor disability. Postural instability, psychological features, and sleep disorders are as important as motor disability and are associated with increased mortality (Lang, 2007).
Summary
Parkinson’s disease is the second common neurodegenerative disorder after Alzheimer’s disease. The disease pathological characteristic is loss of dopamine producing neurons in the substantia nigra. There are biological, environmental, and genetic factors blamed for dopamine accumulation and consequently cell death. Characteristic clinical features of the disease include the motor tetrad of tremors, muscle rigidity, bradykinesia, and postural disturbances. Non motor features including dementia, mood disorders and depression represent an important burden on caregivers in moderate and advanced cases. Treatment possibilities include medical and surgical treatment, however genetic therapy represent the key to future treatment.
References
Bunting-Perry, L., K. (2006). Palliative Care in Parkinson’s Disease: Implications for Neuroscience Nursing. Journal of Neuroscience Nursing, 38(2), 106-113.
Habermann, T., M., and Ghosh, A., K. (2008). Mayo Clinic Internal Medicine Concise Textbook. Rochester, MN: Mayo Clinic Scientific Press.
Lang, A. (2007). Parkinsonism. Chapter 433 in Ausiello, DA, and Goldman, L. (editors). Cecil Textbook of Medicine. Saunders. St. Louis.
Lee, P., W., H., Chang, P., C., M., Fung, S., M., and Leung, P., W., L. (1994). Issues in the Care of Elderly Patients with Parkinson’s Disease: Cognitive Impairment, Daily Life Adjustment, Behavioural/Emotional Problems and Caregiver Burden. J. Hong Kong Coll. Pschiatr., 4, 21-27.
Lotharius J. and Brundin P. (2002). Pathogenesis of Parkinson’s Disease: Dopamine, Vesicles and α synuclein. Neuroscience, 3, 1-11.
Mahlon, R., Juncos, L. (2004). Parkinson’s disease and other movement disorders. Chapter 351 in Braunwald, E., Fauci, A., Hauser, S., Jameson, J. L., Kasper, D. L., & Longo, D. (editors). Harrison’s Principles of Internal Medicine 16th Edition. New York: McGraw-Hill Professional.
Moore, D J., West, A B., Dawson, V L. and Dawson, T M. (2005). Molecular Pathophysiology of Parkinson’s Disease. Annu. Rev. Neurosci., 28, 57-87.
Nutt, J G. and Wooten, G. F. (2005). Diagnosis and Initial Management Of Parkinson’s Disease. N Engl J Med, 352, 1021-1027.
Recchia, A, Debetto, P, Negro, A. et al (2004). α-Synuclein and Parkinson’s disease. FASEB J., 18, 617-626.
Samuel, M., Maidment, I., Boustani, M., and Fox, C. (2006). Clinical management of Parkinson’s disease dementia: pitfalls and progress. Advances in Psychiatric Treatment, 12, 121-129.