Essential tremor is considered to be a tremor syndrome characterized by isolated bilateral upper-limb action tremor with a duration of at least 3 years, with or without tremor in other locations, such as head, larynx (voice tremor), or lower limbs.
Essential tremor frequently manifests with additional mild neurologic signs of diagnostic uncertainty, such as mild ataxia, questionably abnormal posturing of the limbs, or impaired memory. This presentation is classified as “essential tremor plus.
Criteria for Essential Tremor and Essential Tremor Plus of the International Parkinson and Movement Disorder Society
Essential tremor
- Isolated tremor syndrome characterized by bilateral upper-limb action tremor
- Duration of at least 3 years
- With or without tremor in other locations (e.g., head, voice, or lower limbs)
- Absence of other neurologic signs, such as dystonia, ataxia, or parkinsonism
Essential tremor plus
- Tremor with the characteristics of essential tremor and additional neurologic signs of uncertain clinical significance such as impaired tandem gait, questionable dystonic posturing, memory impairment, or other mild neurologic signs that do not suffice to make an additional syndrome classification or diagnosis
- Essential tremor with additional tremor at rest should be classified as essential tremor plus
Clinical features of essential tremor and Parkinson’s disease
| Feature | Parkinson’s disease (PD) | Essential Tremor (ET) |
| Usual duration of symptoms before medical contact | 6–12 mo | Usually several years or more |
| Family history | Generally negative (5%–15% with an affected first-degree relative) | Often positive (>60%), autosomal dominant |
| Response to small amount of alcohol | Little or none | Often improves |
| Position of maximal activation | Rest | Maintenance of posture or with movement |
| Frequency | 3–6 Hz | 6–12 Hz |
| Morphology | Pill-rolling | Flexion-extension |
| Onset | Unilateral | Bilateral |
| Body parts affected | Upper limb, lower limb, chin, lips, or tongue | Upper limb, head, voice |
| Handwriting | Micrographic, atremulous | Normal size, tremulous |
| Associated signs (eg, bradykinesia, hypomimia) | Present | Absent |
| Is the tremor present when walking? | Yes | No |
References:
- Haubenberger D, Hallett M. Essential Tremor. N Engl J Med. 2018 May 10;378(19):1802-1810 [Medline]
- Reich SG. Essential Tremor. Med Clin North Am. 2019 Mar;103(2):351-356. [Medline]
Created May 15, 2019
