William Ondo, MD
Disclaimer: For diagnosis, consult a neurologist specializing in movement disorders.
While most people are familiar with Parkinson’s disease (PD), essential tremor (ET) is much less known, yet actually much more common – 8 times more common. Essential tremor is also referred to as benign tremor, familial tremor, or idiopathic tremor.
Tremors can happen at rest or when attempting an action. In order to begin to understand the differences between the two diseases, first it is important to identify the different types of tremors as defined in Thenganatt and Louis (2012).
To distinguish between these two conditions, a neurologist specializing in movement disorders will perform neurological testing which may include holding arms straight out in front of the body, touching a finger to the nose and drawing spirals. This will enable the neurologist to evaluate the features of the tremor including frequency (number of repetitions per second) and amplitude (strength of tremor).
Below are the 10 symptoms that distinguish between the two diseases:
|Essential tremor||Parkinson tremor|
|Tremor is the primary symptom, although there may be problems with the way a person walks (gait) or balance.||Symptoms include bradykinesia (slowness in the execution of movement), rigidity, tremor and gait/balance issues.|
|Amplitude is variable, ranging from barely noticeable tremor to a high amplitude tremor.||High amplitude.|
|High, fast frequency which may decrease as the disease progresses.||Low, slow frequency (4 to 6Hz).|
|Action tremor. However, rest tremor has been reported with more severe disease and longer disease duration in various studies.||Resting tremor. However, postural tremor has been reported in patients with PD.|
|Writing tends to be large and shaky.||Writing tends to be slow and small.|
|Kinetic tremor is generally of greater amplitude than postural tremor in ET.||Rarely kinetic.|
|Family history in >50% of patients.||Rarely family history.|
|Usually affects both sides of the body (bilateral) and typically not the same on both sides.||Usually starts on one side of the body and progresses to the other side.|
|Can begin at any age, but is most common in middle age.||Generally begins around 60 years of age.|
|Affects hands, head and voice, but rarely legs.||Affects hands and legs, but rarely head and voice.|