Table 1
Results of Search for Articles from PubMed Using Various Key Words and their Combinations
| Key Words and Combinations | Number of Publications | ||
|---|---|---|---|
| Total | Included | Excluded | |
| Essential tremor AND premotor | 29 | 4 | 25 (not in English: 0, not relevant: 25) |
| Essential tremor AND prodromal | 5 | 0 | 5 (not in English: 0, not relevant: 5) |
| Essential tremor AND non-motor | 71 | 24 | 47 (not in English: 4, not relevant: 43) |
| Essential tremor AND cognition | 138 | 29 | 109 (not in English: 6, not relevant: 103) |
| Essential tremor AND memory | 71 | 17 | 54 (not in English: 2, not relevant: 52) |
| Essential tremor AND depression | 170 | 26 | 144 (not in English: 12, not relevant: 132) |
| Essential tremor AND apathy | 7 | 5 | 2 (not in English: 0, not relevant: 2) |
| Essential tremor AND anxiety | 101 | 14 | 87 (not in English: 9, not relevant: 78) |
| Essential tremor AND sleep | 74 | 16 | 58 (not in English: 5, not relevant: 53) |
| Essential tremor AND olfaction | 32 | 8 | 24 (not in English: 0, not relevant: 24) |
| Essential tremor AND hearing | 31 | 12 | 19 (not in English: 0, not relevant: 19) |
| Essential tremor AND personality | 44 | 10 | 34 (not in English: 3, not relevant: 31) |
| Total number of articles included for review after removing the duplicates | 45 | ||
| Total number of articles included from the reference sections of the shortlisted articles | 19 | ||
| Total number of articles included from authors’ personal collections | 1 | ||
| Final number of articles include for review | 65 | ||
Figure 1
Flow diagram summarizing the steps of our literature search.
Figure 2
Summary of the evidence that favors the existence of a premotor phase of essential tremor.
Table 2
Future Directions for Research on the Premotor Phase of Essential Tremor
| More population-based longitudinal studies. |
| Confirmation of the results of the studies on the NEDICES cohort in other populations. |
| Longitudinal clinical evaluation of individuals at high risk of developing ET (e.g., unaffected first-degree relatives of ET cases). |
| Functional and structural neuroimaging in high-risk individuals and their correlation with premotor symptoms, if present. |