So you’ve decided to approach your physician with your suspicions of Parkinson’s Disease. Now what? Unfortunately unlike other disease entities like diabetes or high cholesterol, there is no gold standard test yet available. Examining the brain tissue under a microscope upon autopsy can show the typical pathology associated with Parkinson’s. This may be useful in the field of research but of course is not a practical or possible way to diagnose this disease. Instead physicians rely on patient narrative, their observations and clinical judgment in order to render a diagnosis such as this.
A trip to the neurologist’s office often includes reams of questions and clinical testing. What are physicians looking for on physical exam that helps to confirm a diagnosis of Parkinson’s Disease? Much of their neurologic examination is directed towards assessing the presence of the cardinal signs of Parkinson’s - resting tremor, rigidity, bradykinesia and postural instability.
Resting tremor is usually best assessed when the patient is in a seated position with their arms relaxed and hands in their lap. Sometimes, particularly early in the disease patients may need to be distracted for example by counting backwards from 10, in order to bring out the tremor. In addition to the resting tremor that characterized Parkinson’s, there are also other kinds as well. Postural tremor is observed when the arms are in an outstretched position and kinetic tremor occurs with voluntary movement and is usually assessed by the finger-to-nose test (where the patient touches their nose with their index finger and then touches the examiner’s finger which changes positions with each try). Although resting tremor is an expected abnormality, many patients have a combination of these different types of tremors.
Bradykinesia or slowness of movement is present to varying degrees throughout the course of disease. In Parkinson’s, a lack of spontaneous facial expressions and decreased blink rate are often observed. The speed of a patient’s movement may also be ascertained through repetitive movement such as opening and closing each hand or tapping the index finger and thumb against each other repetitively - large movements as quickly as possible. In Parkinson’s the movement may start off quick and precise but it will soon deteriorate, becoming slow and limited. Gait is also another way to test for bradykinesia. Observing a patient while they walk and the length of their stride as well as the speed at which they mobilize can be telling. Lack of arm swing is also a feature that is observed fairly early in the course of the disease.
Rigidity or increased tone is assessed by passively moving the joints in the upper limb (elbows, wrists) and lower limbs (knees, ankles) looking for resistance. The resistance may be smooth or more spasmodic, known as cogwheeling. This is sometimes made more obvious by the patient actively moving the opposite limb.
Postural instability usually occurs later in the disease and is a significant source of disability for patients. This is tested by the physician quickly and firmly pulling back on a patient’s shoulders while standing behind them. Taking 1 to 2 steps backward in order to regain balance is a normal response while anything more may indicate the presence of this debilitating symptom.
This is by no means a comprehensive list of tests that an experienced movement disorder specialist uses to assess a patient but these are the more common ones that you may undergo. Being aware of these clinical tests and what signs they are trying to elicit, may help demystify your examination and make navigating the diagnostic process a bit easier.