Essential Tremor and Functional Tremor: What’s the Difference?

Essential tremor (ET) is the most common movement disorder among adults. There is another type of tremor called functional tremor (FT). Just like ET, it causes involuntary (uncontrollable) rhythmic movements, usually an arm or leg. It is frequently mistaken for ET or for Parkinson’s disease, but it is not related to either of those.

ET: a physical disorder

ET comes about when certain areas of the brain begin to malfunction, sending incorrect signals to the part of the thalamus that forwards motor (movement) messages to the limbs and head. In other words, there is a physical cause, and it may respond to pharmaceutical or surgical treatment. Unfortunately, many ET patients do not find medication effective, and unless their tremors become severe, they don’t wish to undergo an invasive brain procedure.

FT: a psychogenic disorder?

Functional tremor can occur when the nervous system is not working properly Just as with ET and Parkinson’s tremors, people with FT experience emotional distress and often some degree of disability. However, no underlying physical cause can be found. Because of this, FT is often called a psychogenic disorder, implying that it’s related to a psychological or emotional state. While this does not sit well with FT patients who resent the implication that somehow FT is all in their mind, some studies have found a correlation between FT and higher scores in depression and anxiety. In any case, FT tremors are very real and not imagined.

A comparison of ET and FT

The following summarizes important differences between ET and FT:

Essential Tremor Functional Tremor
Generally appears during intentional activity, such as lifting a glass of water to take a drink. Not associated with any particular activity. May start and stop sporadically for no apparent reason.
Medication or surgical intervention (thalamotomy, Deep Brain Stimulation, MRgFUS) may control tremors Tremors do not respond to medication or surgical intervention
Tremors do not stop when the patient is suddenly distracted Tremors may abruptly stop if the patient is suddenly distracted
Tremors do not respond to motor retraining or conditioning Tremors may be lessened or brought under control with physiotherapy, retraining, or conditioning
Tremors do not respond to hypnosis Some FT patients have found hypnosis helps to reduce or control their tremors
Cognitive behavioral therapy does not help Some FT patients have found cognitive behavioral therapy helpful

 

Living with tremors

ET, FT and Parkinson’s disease are the most common forms of tremors, but there are several less common sources of tremor:

  • Exposure to toxins
  • Traumatic brain injury
  • Stroke
  • Multiple Sclerosis
  • Overactive thyroid
  • Extreme nervousness or panic

Many people with mild tremors that are not due to a neurodegenerative disease are able to live well with them, and cope with any embarrassment that may arise. Once they have a diagnosis and assurance that they do not have a life-threatening condition, they may choose not to seek treatment unless the tremors become more severe. Treatment recommendations will begin with the least intervention needed to bring about the greatest effect.

For ET patients, if tremors increase dramatically, to the point where a quality of life is severely compromised, patients may pursue a treatment to interrupt the dysfunctional messages that are forwarded by the VIM nucleus of the thalamus in the brain. A noninvasive alternative to neurosurgery through an opening in the skull is MRI-guided Focused Ultrasound (MRgFUS). This painless outpatient procedure produces immediate, lasting results.

If you or a loved one is struggling with ET that impairs quality of life and does not respond to medication, contact Sperling Neurosurgery Associates.