Which features are essential for the diagnosis of Parkinson's disease?

For the diagnosis of Parkinson's disease, the essential features identified are resting tremor, bradykinesia, rigidity, and postural instability. Resting tremor refers to the involuntary shaking that occurs when the muscles are relaxed and not in use. Bradykinesia is characterized by slowness of movement, which is a hallmark symptom of the disease. Rigidity indicates increased muscle tone, making movement difficult. Postural instability refers to balance issues, which can lead to falls.

These features collectively represent the core motor symptoms outlined in the clinical criteria for Parkinson's disease. The presence of two or more of these symptoms is typically necessary to make a formal diagnosis, indicating how they are integral to recognizing the condition effectively. In contrast, the other options present symptoms that may be associated with other conditions or are not primary criteria for diagnosing Parkinson's disease.