Parkinson, James
(par'kĭn-sŏn 
)
Brit. physician, 1755–1824.
ABBR: PD
A common, chronic degenerative disease of the central nervous system that produces progressive movement disorders and changes in cognition and mood.PD is diagnosed in 1.5% to 2% of the population over 60. The disease is rarely identified earlier in life. In the U.S., the disease is much more common in European Americans than in people of African or Asian heritage. It is also more common in the Midwest and Northeastern U.S. than in other regions of the country.
Its underlying causes are not precisely known; it is clear, however, that dopamine production by brain cells in the substantia nigra is diminished in the disease. Although PD often clusters in families, it is uncertain whether this is the result solely of genetics or of exposure to common precipitating agents (viruses, toxins, chemicals or drugs) since some cases of PD cluster in certain environments.
Its hallmarks include a “pill-rolling” tremor of the hand s, muscular rigidity, loss of facial expression, difficulty initiating movements (akinesia, bradykinesia), and gait disturbances (esp. shuffling gait, festination, and , sometimes, difficulty initiating forward movements). Most patients report gradual onset of fatigue, or malaise, followed by evidence of a tremor in one or more extremities, typically a hand when it is at rest. Such tremors increase during periods of anxiety or stress but decrease during purposeful motion or sleep. Other common symptoms include difficulty getting up from a chair or turning over in bed, a change in vocal quality (a softer, less audible, more monotonous voice), shuffling gait that becomes faster after a few steps (festination), and a stooped posture. As the years pass, frequent falls may occur. Occasionally a tendency to fall backward (retropulsion) replaces festination. Facial expressiveness may diminish (patients are said to have a masklike or immobile face), swallowing often becomes impaired, and hand writing may become smaller or more cramped (micrographia).
Other than a physical exam for the symptoms and signs, there is no test to diagnose PD. A substantial dose of carbidopalevodopa may be given to treat PD; a significant improvement with this medication will often confirm the PD diagnosis.
The goal of treatment is to maintain function for as long as possible and relieve symptoms. Medical therapies include selegiline, levodopa/carbidopa; dopamine agonists, e.g., bromocriptine; inhibitors of catechol-O-methyltransferase, e.g., entacapone, and monoamine oxidase-B inhibitors, e.g., deprenyl. Surgical therapy, which is performed at a small number of hospitals, may involve transplantation of dopamine-secreting cells (fetal brain tissue, nerve cells from other parts of the patient's body) into affected areas of the brain or insertion of electrical brain stimulators into the subthalamic nucleus, globus pallidus internus, or ventral intermediate nucleus. Surgical lesion therapy incudes pallidotomy, thalamotomy, or subthalamotomy. Physical therapy is very important because it helps maintain muscle tone and function.
Teamwork benefits the PD patient, who may require a social worker, nurses, primary care providers, a neurologist, registered dietitian, physical therapist, occupational therapist, and speech therapist. Patients should be monitored for the efficacy and safety of drug therapy, particularly when a new drug is prescribed. Drug-drug interactions are common but may be avoided with careful dose titration and prescribing. Older patients are at increased risk for adverse effects because of reduced drug tolerance and should be assessed for postural hypotension, pulse irregularities, blepharospasm, and anxiety and confusion. Drug dosages should be reduced if adverse side effects occur. If patients have periods of immobility alternating with periods of severely impaired mobility, they may need changes in their medication schedule or new, additional medications. The patient and family are taught safety measures to prevent injury caused by falling, as well as swallowing techniques to deal with dysphagia. Prescribed drugs are administered and evaluated for desired effects and adverse reactions; the patient is instructed in their use and potential side effects so that the dosage can be adjusted to minimize the side effects. The nurse, physician, or occupational or physical therapist teaches the patient and family about safety measures to prevent injury, about drug-related dietary restrictions, and about the need for frequent small feedings to provide needed fluids, calories, and dietary bulk. Drinking at least 2 L/day of liquids and eating a high-fiber diet help to establish a regular bowel routine; an elevated toilet seat and frame can help the patient in moving from sitting to stand ing position. Independence is encouraged. The patient should plan daily activities for when he or she feels rested to prevent fatigue, but even so, the patient needs to exercise regularly (active and passive range of motion, walking, massage, baths, carrying out activities of daily living) to help relax muscles and prevent contractures and muscle atrophy. Education about progression of the disease and emotional support are provided; the family is assisted to recognize and fulfill the patient's need for intellectual stimulation and recreation. The patient is also referred to national organizations, e.g., the National Parkinson Foundation, Inc.; www.parkinson.org, for additional information.
Diseases that may be confused with Parkinson disease include corticobasal ganglionic degeneration, Lewy body dementia, multiple system atrophy, and progressive supranuclear palsy.
Variant: parkinsonian facies
The immobile, masklike facial expression with infrequent eye blinking, a hallmark of PD and postencephalitic states.