Parkinson's disease, a debilitating neurodegenerative condition, results from loss of pigmented cells in a part of the midbrain called the substantia nigra. The substantia nigra connects heavily to the striatum, the brain's central relay station or "trigger point" for sending electrical signals to the muscles to execute smooth, purposeful movement. Because these connections are disrupted in Parkinson's disease, people affected by the condition have problems with flexibility, posture and with the performance of everyday activities. According to the American Parkinson Disease Association, more than 1.5 million people suffer from Parkinson's. The condition occurs with higher frequency in men and in those older than age 60.
Tremor
Parkinsonian tremors happen prominently in the hands and feet, manifesting as stereotyped back-and-forth motions. Typically, a person in the early stages of Parkinson's will experience trembling only on one side of the body. As the disease progresses, however, shaking will spread laterally to the other side and then include the arms, legs, head and jaws. The shaking usually mitigates during strong voluntary movement such as quickly reaching out for an object, but grows worse under psychological stress.
Rigidity
Rigidity refers to increased muscle tone or stiffness in the limbs and torso. People with advancing Parkinson's will display chronic inflexibility in which the muscles feel tightened. Constant muscle contraction without the benefit of periodic relaxation can limit degrees of physical motion, and cause painful cramping and weakness. The National Institute for Neurological Disorder and Stroke states that rigidity in Parkinson's applies to passive as well as active displacement; when another person moves the arm of someone with Parkinson's, the arm will bend almost mechanically, not fluidly.
Bradykinesia
Bradykinesia refers to decreases in the amplitude and speed of conscious or unconscious movement, and trouble initiating action. Because of slowed or delayed movement, people with Parkinson's will exhibit difficulty carrying out routine tasks such bathing or dressing--and in later stages of the disease--with chewing and swallowing food. Speech changes might also occur, along with changes in the ease with which a person can show facial gestures.
Impaired Balance and Coordination
According to the American Parkinson Disease Foundation, Parkinsonian patients develop a clinically definable gait that impacts the way they walk. People with the condition will tend to hunch over as they step forward, keeping their arms tucked in and their shoulders drooped. Their stride might be interrupted or wholly characterized by small, pitter-patter-like steps that make it hard to turn. This shuffled pattern of walking increases the chances of falling.
