Parkinson's disease

What is Parkinson's disease?

Parkinson's disease is a progressive degeneration of nerve cells in the part of the brain that controls muscle movements. The loss of nerve cells results in depletion of a chemical (dopamine) that is important for transmitting signals from one group of cells to another within the brain. As a result, walking, arm movements, and facial expressions are impaired. The cause of Parkinson's disease is unknown. The disease usually begins in middle or late life and develops very slowly.

How is it diagnosed?

History: Early symptoms are often related to muscle rigidity and include complaints of slowness of movements and vague heaviness, stiffness, or aching in the limbs. As the disease progresses, a stooped posture develops. The individual experiences difficulty maintaining balance. It may become difficult for the individual to get up from a seated position and begin walking. The gait itself is characterized by small, shuffling steps and a loss of the normal automatic arm swing. There may be unsteadiness on turning, difficulty in stopping, and a tendency to fall. In the earlier stages, intellectual abilities are unaffected, but some degree of dementia eventually occurs in at least one-third of individuals.

Depression is also common. The development of symptoms is often slow. In fact, the individual may be unaware of exactly what is happening. The early clinical presentation of Parkinson's may also confuse the physician, particularly if the characteristic tremor is not yet present.

Physical exam: Individuals often present with infrequent blinking of the eyes and a blank stare. Voluntary and emotional facial movements are both limited and slow. Speech is monotonous, and, as the disease progresses, becomes difficult or impossible to understand. Drooling may be apparent. Motor examination reveals that strength is normal, but voluntary and spontaneous tasks are made difficult by rigidity and slowness in the initiation of movement. Rigidity is found in most muscles although, it may initially be confined to one limb. At first, only a slight rigidity may be felt within the muscles on movement, but eventually a ratchet-like jerking is felt. Handwriting changes are often useful early diagnostic signs as the writing becomes shaky and the letters small. Parkinsonian tremor is characteristic when present.

Tests: There are no diagnostic tests for Parkinson's disease. Medical tests may be performed, to eliminate other causes of disease. A response to medication is supportive of the diagnosis.

How is Parkinson's disease treated?

No cure exists for Parkinson's disease, and the illness is progressive. The mortality rate of individuals with Parkinson's disease may be reduced if therapeutic drug use is introduced within three years following the onset of symptoms, rather than at a later stage.

• Drug therapy is the single most effective treatment for Parkinson's disease. It improves all of the major features of Parkinson's disease, but unfortunately, does not stop its progression. After five years, greater than 50% of individuals begin to experience fluctuations in their response to the drugs ("on-off" effect). Drugs may affect the natural history of Parkinson's disease by slowing down its progressive course.
• Physical therapy or speech therapy helps many individuals physically handle their disability.
• Surgical treatment may be helpful in selected individuals become unresponsive to medication or develop intolerable adverse drug reactions. For these individuals, brain tissue in areas called the thalamus and globus pallidus is sometimes surgically destroyed (thalamotomy).

Medications

Anticholinergics; antihistamines; antidyskinetics; antitremor drugs, such as amantadine; or antiparkinson medications (dopamine stimulators, dopamine precursors), including bromocriptine, levodopa and carbidopa. Selegiline is prescribed to maintain maximal effectiveness of levodopa and carbidopa. All these decrease tremors and reduce muscle rigidity, but they often have significant side effects.

Symmetrel (Amantadine), Seroquel (Quetiapine), Ambien (Zolpidem)

Activity

Remain as active as possible, and rest often. Physical abilities vary greatly between persons with this disease. The only restrictions are those imposed by muscle rigidity.

What might complicate it?

Complications of the disease include difficulty moving and speaking, confusion, depression, aspiration pneumonia, weight loss, and falls and injury.

Predicted outcome

The symptoms of Parkinson's disease can be relieved or controlled. There is, however, no cure, and all individuals will continue to deteriorate. Life expectancy is not significantly reduced unless onset is under 50 years of age.

Alternatives

Differential diagnoses may include Wilson's disease, striatonigral degeneration, essential tremor, Creutzfeldt-Jakob disease, Huntington's disease, Shy-Drager syndrome, progressive supranuclear palsy, cortical basal ganglionic degeneration, stroke, and hydrocephalus.

Type of rehabilitation

Physical therapy, including range of motion exercises (ROM), occupational therapy, and speech therapy may be useful in special cases, one to five times a week, for limited periods.

Appropriate specialists

Neurologist, physical therapist, occupational therapist and speech therapist.

Last updated 7 August 2011