The frequency of essential tremor has a negative logarithmic relationship with tremor amplitude that is probably determined by the low-pass filtering properties of skeletal muscle. Tremor frequency also has a strong negative correlation with age but not duration of illness. Therefore, aging per se may affect the clinical expression of essential tremor. Both tremors may therefore have a common origin. Older patients typically exhibit hand tremors with frequencies of 4 to 7 Hz.
Essential tremor is a postural tremor with a variable kinetic component.
Tremor in repose is observed only in the most advanced cases and differs from the complex pill-rolling hand tremor of Parkinson disease. Most patients with essential tremor have no other abnormal neurological signs. However, tremor resembling essential tremor is seen in many other neurological disorders, including Parkinson disease and dystonia. The relationship of essential tremor to action tremors in other disorders is unknown because essential tremor has no unique diagnostic features. No abnormalities have been found in autopsies of patients with essential tremor.