Parkinson's disease is a degenerative disorder of the nervous system characterized by progressive loss of coordinated voluntary and involuntary movement. Parkinson's disease symptoms vary over time, often overlapping with symptoms of other illnesses and conditions. Symptom similarity between Parkinson's disease and other conditions can present a diagnostic challenge, as there is no definitive test for Parkinson's disease.
Tremor
A tremor is an involuntary back-and-forth motion that can affect the limbs, trunk, head and voice. Tremors are commonly known as "the shakes." Hand tremor is often the first symptom of Parkinson's disease, but also occurs with many other diseases and conditions, including stroke, overactive thyroid disease, alcohol or drug withdrawal, head injury and liver failure.
The National Institute of Neurological Disorders and Stroke reports that the most prevalent cause of tremor is a condition known as essential tremor, which is a familial disorder characterized by tremors without other neurological problems. As with Parkinson's disease, essential tremor most commonly affects the hands, typically involving one hand at the onset. Unlike the tremor of Parkinson's disease, essential tremor is most active when the hand in use. In contrast, Parkinson's disease tremors are most prominent at rest and improve with deliberate movement. The absence of other neurological problems with essential tremor stands in stark contrast to Parkinson's disease, which is characterized by a broad array of neurological abnormalities. The familial nature of essential tremor also distinguishes this disorder from Parkinson's disease, which most often occurs sporadically.
Myoclonus
Myoclonus is involuntary muscle jerking or relaxation, which may resemble some of the abnormal body movements that occur in people with Parkinson's disease. The National Institute of Neurological Disorders and Stroke notes that myoclonus may be a symptom of several conditions and disorders, including stroke, liver or kidney failure, head injury, nervous system infections, spinal cord injury, certain types of poisoning, multiple sclerosis, Creutzfeldt-Jakob disease, juvenile myoclonic epilepsy and Alzheimer's disease. Concurrent signs and symptoms, the symptom history, the age of the patient and diagnostic test results provide important information to help distinguish between movement abnormalities due to Parkinson's disease versus other possible causes.
Ataxia
People with ataxia exhibit varying degrees of muscular incoordination, leading to difficulty with voluntary and involuntary movement. As noted on MayoClinic.com, manifestations of ataxia include loss of balance, unsteadiness, frequent stumbling, an unusual walking pattern or stance, swallowing difficulties, slurred speech, clumsiness and difficulty using the hands. Ataxia frequently occurs in people with Parkinson's disease, but also presents with a variety of other disorders, including heavy metal poisoning, Wilson's disease, brain tumor, multiple sclerosis, stroke, cerebral palsy, head injury and certain inherited disorders of the brain and spinal cord.
References
- National Institute of Neurological Disorders and Stroke: Parkinson's Disease
- National Institute of Neurological Disorders and Stroke: Tremor
- National Institute of Neurological Disorders and Stroke: Essential Tremor
- National Institute of Neurological Disorders and Stroke: Myoclonus
- MayoClinic.com: Ataxia
