As the disease slowly destroys nerve cells in the brain, the first symptoms of Parkinson's appear. The four hallmark symptoms are tremor (shaking) of the hands, arms, legs and face; slow movement (bradykinesia); stiffness; and difficulty with balance and coordination.
The disease is different in each person. Some people may become completely disabled relatively quickly, while others have only minor symptoms and get worse very gradually. In general, the symptoms will progress until the person notices distinct changes in his or her ability to walk, talk and perform other everyday activities. In the later stages of the disease, people with Parkinson's can develop a shuffling walk, muffled speech, small and illegible handwriting, emotional changes (including depression), a blank stare, difficulty chewing and swallowing, and constipation.
No single test can identify Parkinson's disease. Usually diagnosing the condition is a matter of ruling out similar diseases with the same symptoms. The doctor will first take a thorough health history and do a neurological test. Blood tests and magnetic resonance imaging (MRI) scans can rule out other diseases. People with at least two of the four hallmark symptoms of Parkinson's disease, and who respond to the drug levodopa, are said to have the disease.
Doctors can stage the severity of the disease using the Hoehn and Yahr Staging and Unified Parkinson's Disease Rating Scale.
The Hoehn and Yahr scale helps doctors describe the severity of symptoms based on five stages:
- Stage 1 -- symptoms are only on one side of the body
- Stage 2 -- symptoms are on both sides of the body, but balance isn't impaired.
- Stage 3 -- there is some balance impairment and disability.
- Stage 4 -- disability is severe, but the person can still walk or stand without help.
- Stage 5 -- the person cannot stand or walk, and is wheelchair-bound or bedridden.
The Unified Parkinson's Disease Rating Scale helps doctors follow the course of Parkinson's by tracking:
- Intellectual impairment, depression, motivation
- Activities of daily living (speech, swallowing, handwriting, cutting food, dressing, hygiene and walking)
- Motor skills (speech, facial expression, tremor, rigidity, posture and walk)
Within each of these areas is a list of functions. Each function is rated on a four-point scale, from normal (0) to significant problems (4). There are a total of 199 points, with 0 being no disability and 199 being total disability.