Parkinson's disease (PD) is a neurological condition characterized by dysfunctional movement. It results when the brain cells responsible for the production of dopamine are damaged or die. Dopamine is a chemical that helps coordinate muscle movements. This explains why the cardinal symptoms are resting tremor in one or more limbs, slowness of movements, rigidity in the limbs or the trunk and balance problems. There is no definitive test for PD; it is diagnosed through a neurological exam and the taking of a thorough medical history. At least two of the cardinal symptoms must be present before a diagnosis of Parkinson's can be made.
Resting Tremor
The first noticeable symptom for many people with Parkinson's is a trembling or shaking movement, usually only on one side of the body such as in a single hand, arm or leg, though it can also appear in the jaw or face. It is evident at rest or when the person tries to hold an arm or leg out away from the body. This is called a resting tremor, and as the name implies, it stops when the limb is in motion. A resting tremor must be differentiated from an essential tremor, which occurs during activity.
Slowness of Movement
While slowness of movement, or bradykinesia, may at first be dismissed as part of the normal aging process, it is one of the more debilitating aspects of the disease, even in the earlier stages. Bradykinesia is often noticed when the person's handwriting becomes small or cramped. It may also be apparent during walking, when the person exhibits a fairly distinctive slow, shuffling gait. At some point, movement may also appear slow when the person is eating, dressing or carrying out other daily activities.
Rigidity
Another early sign is rigidity, or stiffness, in either the trunk or the limbs. However, like the resting tremor, it may initially be found on only one side of the body, quite often in a shoulder. This is another symptom that people may write off as a normal arthritic-type change that occurs during aging, and indeed PD patients are not infrequently treated for shoulder arthritis before they are diagnosed with Parkinson's.
Rigidity combined with bradykinesia sometimes makes it difficult for those with PD to initiate movement, meaning it may take a few moments for them to take a first step or reach for an object.
Balance Problems
Bradykinesia and rigidity also contribute to the postural instability that sometimes occurs in the early stages of PD. Maintaining an adequate pace and swinging the arms are both ways humans keep their balance while walking, and both of these are impaired by rigidity and slowness of movement. The postural instability that may occur in the early stages of Parkinson's may also manifest as frequent falls or a more stooped posture.
Other Symptoms
Another not uncommon early feature of PD is a blank or staring facial expression. The person may not blink, smile or gesture normally or at all while speaking.
For some, speech may be affected. For example, a person may speak more softly or hesitantly, or slur or repeat words.
