Figure 1
PRISMA Flow Diagram for Number of Studies That Were Identified, Screened, and Included in This Review
Table 1
Clinical Assessment of Balance and Mobility in Essential Tremor
| First Author | ET (n) Control (n) | Mean Age (Years) | Method | Main Results |
|---|---|---|---|---|
| Singer et al.9 | 36 30 | 69.9; 69.2 | Tandem walk (≥ 2 missteps); tremor score; | ET patients had more tandem missteps than controls; 50% of ET patients had tandem walk abnormality; ET patients with missteps were older; tremor severity was not associated with tandem missteps |
| Hubble et al.7 | 60; 60 | 68; 68 | Tandem walk (≥ 2 missteps); tremor score | ET patients had more missteps during tandem walk; 50% of ET patients had tandem walk abnormality; age was a significant predictor of missteps |
| Lim et al.10 | 41; 44 | 60.9; 58.9 | Tandem walk (≥ 2 missteps) | 29% of ET patients had tandem walk abnormality; 70% older ET patients (> 70 years) had tandem walk abnormality |
| Louis et al.8 | 122 | 77.1 | NE; tandem walk (≥ 2 missteps) | Tandem missteps were correlated with age, age of tremor onset, and the presence of neck and voice tremors; 30% of ET patients had tandem walk abnormality. Tandem missteps increased with cranial tremor score |
| Louis and Rao22 | 120 | 71.3 | Tandem walk (≥ 2 missteps); TICS | Tandem missteps correlated with age, cranial tremor, and TICS score; tandem walk abnormality was seen in 52% ET patients |
| Parisi et al.20 | 16 ET head tremor, 14 ET no head tremor; 28 control | 59.4; 57.1; 58.4 | Clinical tests of balance (TUG, ABC and DGI); tremor score | ET patients with head tremor performed worse on clinical tests of balance and mobility except the Berg balance scale |
| Louis et al.11 | 59; 82 | 71.2; 71.6 | NE; clinical tests of balance (ABC-6; BBS; falls, near falls) | Balance confidence was low in ET, particularly patients with head tremor; near falls highest in ET with head tremor (40% had >5 near falls) in comparison with controls (13% had > 5 near falls) |
| Cinar et al.6 | 90; 50 | 61.4; 60.9 | Tandem walk; tremor score | First misstep occurred earlier in ET and was negatively correlated with age, and tremor score |
| Louis and Rao41 | 126 ET; 77 PD; 46 Dystonia 173 controls | 75.7; 74.4; 73.2; 74.1 | NE; clinical tests of balance (ABC-6; falls, near falls) | Balance confidence, number of falls, and near falls were lowest in PD, followed by ET. Need for walking aids was greatest in PD, followed by ET cases |
| Louis et al.42 | 100 | 80.5 | NE, tandem walk, ABC; physical activity, MoCA | Lower physical activity associated with age, tandem missteps, MoCA score, and higher tremor score; tandem missteps, tremor score, and MoCA score were independent predictors of physical activity |
[i] Abbreviations: ABC-6, Activities of Balance Confidence Scale; BBS, Berg Balance Scale; DGI, Dynamic Gait Index; ET, Essential Tremor; MoCA, Montreal Cognitive Assessment; NE, Neurological Examination; PD, Parkinson’s Disease; TICS, Telephone Interview of Cognitive Status; TUG, Timed Up and Go.
Table 2
Quantitative Analysis of (a) Balance and (b) Gait in ET
| First Author, Year | ET (n) Control (n) | Age (Years) | Method | Outcomes | Results |
|---|---|---|---|---|---|
| (a) Studies on quantitative assessment of balance (listed chronologically) | |||||
| Bove et al.12 | 19 ET; 19 control | 64.1 59.9 | QP (Quiet stance, cognitive and motor dual task, eyes open and closed) | 1. Center of pressure (COP) area; 2. COP path; 3. COP x displacement; 4. COP y displacement | COP path was greater in ET with head tremor; COP area and path increased with eyes closed and during dual cognitive or motor task in both groups |
| Parisi et al.20 | 16 ET head tremor, 14 ET no head tremor; 28 control | 59.4 57.1 58.4 | QP (stance eyes open and closed) | 1. Tremor score; 2. Falls; 3. Near falls; 4. COP displacement; 5. COP speed | There were no significant differences in COP sway and speed between ET and controls |
| Hoscovcova et al.13 | 30 ET 25 control | 55.8 53.0 | Tremor score; clinical tests of balance (ABC, FAB); QP (normal and tandem stance) | 1. Tremor rating scale; 2. ICARS; 3. ABC scale; 4. Fullerton advanced balance scale; 5. Acceleration amplitude; 6. Acceleration frequency; 7. Stride length; 8. Cycle time; 9. Support base; 10. Swing time; 11. Stance time; 12. Velocity; 13. Tandem missteps; 14. Sway path; 15. Sway path; 16. COP area | No differences between ET and controls during normal gait; during tandem gait, ET patients had lower velocity and more missteps; COP area was higher in ET during tandem stance; no differences between groups on clinical tests (ABC and FAB) |
| (b) Studies on quantitative assessment of gait (listed chronologically) | |||||
| Stolze et al.19 | 25 ET; 8 Cerebellar; 21 control | 50.3 52.5 52.7 | QG (preferred speed); TW; tremor score | 1. Total tremor score; 2. Gait speed; 3. Stride length; 4. Cadence; 5. Step width; 6. Foot angle; 7. Step height; 8. Stance time; 9. Swing time; 10. Double support time; 11. CoV; 12. Tandem missteps | Preferred walk: ET patients walked with greater step width; Tandem walk: ET patients had wider step width and more missteps than controls; Step width and tandem missteps were associated with intention tremor |
| Kronenbuerger et al.14 | 25 ET no DBS; 12 ET DBS; 25 control | 46.3 64.2 46.3 | QG (preferred and tandem gait on treadmill); QP; | 1. Stride length; 2. Cadence; 3. Stance phase; 4. Number of missteps; 5. Sway area; 6. Falls; | ET had shorter stride length and more missteps; ET had greater sway when vision was absent/sway referenced and platform tilt was sway referenced; DBS did not improve gait and posture |
| Rao et al.15 | 104 ET; 40 control | 86 84.1 | NE; QG (preferred and tandem walk on GAITRITE) | 1. Gait Speed; 2. Step length; 3. Cadence; 4. Stride time; 5. Double support % 6. Step time difference; 7. Step width; 8. CoV swing length; 9. CoV stride length; 10. Support base; 11. Tandem missteps | In preferred walk, ET had slow speed and cadence, increased double support percent, and increased asymmetry. In tandem walk, ET had more missteps. Gait impairments were worse for ET than controls across age |
| Louis et al.33 | 4 ET | 38–79 | NE; QG (preferred walk on GAITRITE); clinical tests of balance (ABC, POMA) | 1. ABC-6 score; 2. Tinetti POMA score; 3. Gait speed; 4. Percent time in double support; 5. Step time difference; 6. CoV swing time | ABC score and Tinetti POMA score were lower and tandem missteps were higher in ET; gait speed was lower, percent double support, step time difference and CoV swing time were higher |
| Rao et al.17 | 151 ET; 62 control | 84.4 79.6 | NE; QG (dual task gait on GaitRITE) | 1. Gait speed; 2. Stride length; 3. Cadence; 4. Stride time; 5. Double support time; 6. Step time difference; 7. Step width; 8. CoV Stride length; 9. CoV stride length | Gait most impaired in ET with low cognitive scores (LCS) – less impaired in ET cases with higher cognitive scores (HCS); cognitive motor interference was greatest for ET LCS for double support time, step time difference and CoV stride time |
| Fernandez et al.34 | 24 ET 31 PD; 38 control | 68 68 68 | QG (force plate) | 1. COP displacement; 2. COP velocity; First step length; 3. First step time; first step speed; | COP displacement in AP direction reduced in ET; length of the first step was reduced in ET |
| Roemmich et al.18 | 31 ET 11 Control | 66.5 63.6 | QG (preferred walk on treadmill) | Mean and CV for 1. Stride length; 2. Stride time; 3. Step length; 4. Step time; 5. Step width; 6. α (slope of linear least-squares fit) | During preferred walk, ET had slower gait speed and increased variability; during speed matching, ET had higher step width variability; gait variability was associated with midline tremors |
| Rao et al.28 | 132 ET 48 Control | 83.7 79.5 | NE; ABC; QG (preferred speed GAITRite) | 1. ABC-6 score; 2. Number of falls; 3. Gait speed; 4. Cadence; 5. Step length; 6. Step time difference; 7. Double support %; 8. CoV stride length; 9. CoV stride time | ET with low cognitive scores (LCS) had lower ABC scores and higher number of falls; gait measures correlated with balance confidence and falls; gait speed and ABC-6 score were significant predictors of falls |
| Rao and Louis 16 | 155 ET 60 Control | 81.9 80.1) | QG (in time with metronome on GAITRite); Tremor score | 1. Cadence; 2. Step time; 3. Cadence error; 4. Cadence SD; 5. Cranial tremor score | Cadence was lower in ET; cadence error (accuracy) and cadence SD (precision) were similar in ET and controls; cadence and cadence error were correlated with cranial tremor score |
[i] Abbreviations: ABC, Activities of Balance Confidence; CoV, Coefficient of Variation; DBS, Deep Brain Stimulation; ET, Essential Tremor; FAB, Fullerton Advanced Balance Assessment; ICARS, International Cooperative Ataxia Rating Scale; NE, Neurological Examination; PD, Parkinson’s Disease; POMA, Performance-Oriented Mobility Assessment; QG, Quantitative Gait; QP, Quantitative Posturography; TUG, Timed Up and Go.
Table 3
Studies on the effect of intervention on Balance and Gait in Essential Tremor
| First Author, Year | ET (n) Control (n) | Age (Years) | Intervention | Assessment | Outcomes | Results |
|---|---|---|---|---|---|---|
| Ondo et al.53 | 13 ET | 72.8 | Thalamic stimulation | QP (sensory organization test) | 1. Time to onset of compensatory movements; 2. Amplitude of compensatory movements | Performance on the sensory organization test was worse with DBS off and improved with DBS; |
| Fasano et al.51 | 11 ET 10 control | 69.8; 67.3 | Bilateral thalamic stimulation | NE; QG (standard and tandem walk on treadmill) | 1.Tremor rating scale; 2. Intention tremor score; 3. Spiral score; 4. Postural tremor score; 5. Overground tandem gait velocity; 6. Overground tandem number missteps; 7. Ataxia score; 8. Swing duration CV; 9. Range of motion | 1. Total tremor score, intention tremor, postural tremor, and spiral tremor, was reduced with thalamic stimulation; 2. Supra therapeutic stimulation improved tremor except during upper limb spirals; 3. Number of missteps was reduced on thalamic stimulation, but was higher than healthy controls; 3. Supratherapeutic stimulation increased number of missteps; 4. With assisted tandem gait on treadmill lower limb kinematics were highly variable; 5. Thalamic stimulation improved ataxia ratio and variability |
| Fasano et al.52 | 11 ET 10 control | 69.8; 67.3 | Bilateral thalamic stimulation | NE; QG (standard and tandem walk on treadmill) | 1. ICARS score; 2. Gait speed; 3. Stride length; 4. Swing duration; 5. Double support time; 6. Step width; 7. Step height; 8. Ataxia score; 9. Swing duration CV; 10. Range of motion | 1. Thalamic stimulation reduced intention and postural tremor; 2. Joint ROM in ET patients with normal kinematics was similar to controls; 3. ET patients with impaired kinematics (longer disease duration and greater intention tremor) had higher variability in joint movement; 4. Thalamic stimulation reduced joint variability in ET with impaired kinematics |
| Hwynn et al.56 | 38 ET | 67.1 | Thalamic stimulation (unilateral and bilateral) | NE; QG and falls assessment | 1. Fahn–Tolosa–Marin tremor rating scale; 2. Upper extremity scores (rest tremor, postural tremor, kinetic tremor, drawing spirals, pouring water into cup); 3. Gait and falls assessment | 1. About 70% of patients with unilateral thalamic stimulation and 55% with bilateral thalamic stimulation reported worsened gait; 2. Patients with worsened gait had poor baseline tremor scores |
| Earhart et al.24 | 13 ET; 13 control | 61.6; 63.2 | Bilateral thalamic stimulation | NE; QG (preferred and tandem walk) | 1. ABC Scale; 2. Spatiotemporal gait measured with GAITRite mat; 3. BBS; 4. TUG | 1. ET patients demonstrated tremor reduction with stimulation; 2. During standard and tandem walk, ET patients walked with slower speed, lower cadence, and higher double support during ON and OFF stimulation compared with controls; 3. ET patients performed worse on clinical tests of balance compared with controls; 4. There were no differences with DBS on and off |
| Ulanowski et al.47 | 1 ET | 61 | Physical therapy (balance and functional movement training) for 14 sessions over 8 weeks | Standardized clinical assessment | 1. BBS; 2. FGA, 3. Five-times-sit-to-stand test 4.10-m walk test (10MWT). | After 8 weeks of therapy, the patient had clinically meaningful changes in the five-times-sit-to-stand test, FGA, and BBS. The improvement reduced fall risk |
[i] Abbreviations: ABC, Activities of Balance Confidence; BBS, Berg Balance Scale; CV, Coefficient of Variation; ET, Essential Tremor; FGA, Functional Gait Assessment; ICARS, International Cooperative Ataxia Rating Scale; NE, Neurological Examination; QG, Quantitative Gait; QP, Quantitative Posturography; TUG, Timed Up and Go.