Clinical Features

The disease that subsequently became known as Parkinson’s disease was
called “shaking palsy” by Parkinson. The shaking refers to the tremor which,
although it is thought by many people to be invariably associated with Parkinson’s
disease, may be completely absent, or present to a minor degree, in
some patients. Four symptoms which are present in many patients are a progressive
tremor, bradykinesia and even akinesia, muscular rigidity, and loss
of postural reflexes. There still is no specific test that can be used to diagnose
Parkinson’s disease. No biochemical, electrophysiologic, or radiologic
test has been found to be completely reliable. As a result, misdiagnosis and
underdiagnosis have been common with the disease. The situation is complicated
further as a number of other diseases and conditions share some of
the same symptoms, including Wilson’s disease, familial Alzheimer’s disease,
Huntington’s disease, and encephalitis, as well as responses to certain
drugs. Symptoms of Parkinson’s disease may also develop consequent to
trauma to the brain.
A slight tremor in the hands may indicate the first symptoms of Parkinson’s
disease, and the tremor may or may not also be found in the legs, jaws,
and neck. An interesting symptom that may appear in later stages of the disease
is seborrhea, or acne. Intellectual functioning usually remains normal,
but approximately 20 percent of the patients experience dementia and have
a progressive loss of intellectual abilities and impairment of memory. It is
not yet clear how the dementia of Parkinson’s disease is related to the dementia
associated with Alzheimer’s disease. Depression also may occur in
patients, with approximately one-third of them having depression at any
one time. The depression may be directly related to the disease, or it may be
a reaction to some of the medication.
It has been convenient to divide the progression of symptoms of Parkinson’s
disease into five stages, according to the severity of the symptoms and
the degree of disability associated with them. Stage 1 is marked by mild
symptoms. In this stage, the symptom that brings the patient to a physician is
likely to be a mild tremor, usually limited to one hand or arm. The tremor
usually is reduced or disappears during activity, but it may increase during
periods of emotional stress. During this early stage of the disease, mild
akinesia of the affected side and mild rigidity may be evident. Overall, many
of these changes are subtle enough that the patient is not aware of them or
does not complain of them. Usually, symptoms are confined to one side, but
as the disease progresses, it becomes bilateral in most patients in one or two
years. In Stage 2, there is bilateral involvement. Postural changes lead to the
patient having a stooped posture and a shuffling walk, with little extension
of the legs. All body movements become slower and slower (bradykinesia).
The difficulty and slowness of movements may cause patients to curtail
many of their normal activities and, in many cases, may lead to depression.
Stage 3 is characterized by an increase in the postural changes and movements,
leading to retropulsion, a tendency to walk backward, and to propulsion,
a tendency when walking forward to walk faster and faster with shorter
and shorter steps. As the disease progresses, movements occur more and
more slowly, and there are fewer total movements. By Stage 4, symptoms
have become so severe as to lead to significant disability, and the patient usually
needs constant supervision. The course of the disease leads to Stage 5, a
period of complete disability in which the patient is confined to a chair or
bed. Interestingly, the tremor which is so characteristic of the initial onset of
Parkinson’s disease tends to lessen considerably during the later stages of
the disorder. In addition to the dementia associated with aging, patients
with Parkinson’s disease show an increased risk of dementia, occurring six
to seven times more frequently compared to age-matched controls.