Conclusion Summary for A Pilot Study for Quantitative Assessment of Gait in Essential Tremor Using Wireless Sensors

Principal Investigator: Vibhash Sharma, MD
University of Kansas Medical Center (KU)

January 28, 2020

The pilot study for gait analysis in patients with Parkinson disease (PD), essential tremor (ET) and healthy controls has been completed. Gait analyses were performed during clinic visits. The time taken to perform gait analysis was between 3 to 10 minutes per person.

The Parkinson disease group was very large and diverse, therefore for comparison with the essential tremor group, we identified Parkinson disease patients who were diagnosed in the last five years. Additionally, we also identified ET patients who had normal DaTscan and PD patients who had abnormal DaTscan from our database. We created different groups from the dataset (Table 1).

Table 1

Groups Number of subjects Mean age
PD,  5 years of diagnosis or less 68 66.4 years
ET 71 68.1 years
Healthy Controls 31 63.9 years
ET with normal DaTscan 14 69.1 years
PD, 5 years of diagnosis (or less) with abnormal DaTscan 16 64.1 years

 

Gait measures obtained during gait analysis were analyzed and comparisons between the various groups were done using ANOVA. Pertinent variables amongst different groups (All ET, PD and HC) are summarized in table 2 (below). Comparisons between various groups are summarized below:

  • ET (n=71, mean age 68.1 years) vs Healthy Controls (n=31, age 63.9 years)

Patients with ET were found to have significantly reduced gait speed and stride length compared to healthy controls. There was also a significant increase in double support time and increased toe out angles compared to healthy controls, suggesting impaired dynamic balance. Additionally, ET patients showed an increase in turn duration and reduced turn velocity. When compared to normative data provided by Mobility Lab/APDM, ET patients also showed reduced cadence.

•     PD, 5 years of diagnosis or less (n=68, 66.4 years) vs Healthy Controls (n=31, 63.9 years)

Patients with PD showed significantly reduced gait speed, stride length, turn velocity and arm range of motion compared to healthy controls. PD patients also showed significant increase in duration of turn and number of steps during turn when compared to healthy controls. Cadence was reduced when compared to normative values, but when compared to healthy controls this difference was not statistically significant.

•     PD, 5 years of diagnosis or less (n=68, 66.4 years) vs ET group (n=71, mean age 68.1 years)

On comparing all PD patients with the overall ET group, no significant difference was seen across multiple gait measures including gait speed, gait cycle duration, stride length, double support time, or cadence. ET patients were found to have an increase in double support time compared to PD and arm range of motion was reduced in PD compared to ET, however only reduction in left arm range of motion in PD patients compared to ET was statistically significant.

To further assess gait parameters between PD and ET, gait measures obtained from patients with PD diagnosed in the last 5 years with abnormal DaTscan were compared with ET patients who had a normal DaTscan.

•     PD, 5 years of diagnosis or less + Abnormal DaT scan (n=16, 69.1 years) vs ET + Normal DaTscan (n= 14, 64.1 years).

On comparing gait measures no significant difference was noted among different gait measures including cadence, gait speed, stride length, or gait cycle duration. Again, ET patients showed increased double support time and toe out angle when compared to PD, but these changes were not statistically significant.

As several of our patients with PD were on dopaminergic medications at the time of gait analysis which can affect gait measures, we identified PD patients who were 1) OFF of levodopa at the time of gait analysis or 2) newly diagnosed PD patients not on dopaminergic medications. We compared gait measures in this group of PD patients (n=22) with healthy controls and ET.

•     PD diagnosed < 5 years (with no medications) (n=22, 61.5 years) vs Healthy   controls (n=31, 63.9 years)

PD patients had significantly lower gait speed and stride length. Cadence was reduced in PD patients, but the difference was not statistically significant. There was significant reduction in upper limb arm velocity and range of motion in PD compared to controls. Additionally, lower limb foot strike angle was significantly lower in PD patients. The duration of turn was significantly higher in PD patients and turn velocity was significantly reduced. The number of steps during a turn was higher in PD, but this difference was not statically significant.

•     PD diagnosed < 5 years (with no medications) (n=22, 61.5 years) vs ET patients (n = 71, 68.1 years)

Both PD and ET showed similar cadence, gait speed, gait cycle duration and stride length. ET patients had significantly increased double support time and increased duration for anticipatory postural adjustment. PD patients showed reduced arm swing velocity on left (p>0.05) and reduced arm range of motion bilaterally (p<0.05). There was no significant difference in turn duration, turn velocity and number of steps in turn (p>0.05).

•     PD diagnosed < 5 years (with no medications) (n=22, 61.5 years) vs ET patients with negative DaTscan (n = 15, 69.1 years)

Both PD and ET showed similar cadence, gait speed, and gait cycle duration. ET patients had significantly reduced stride length as compared to PD. This result is likely due to parkinsonian features in ET patients in this group due to which DaT scan was obtained. We did not see this difference in stride length in other comparisons.

ET patients had significantly increased double support time (p<0.05) and increased toe out angle but not statistically significant. PD patients showed reduced arm swing velocity and reduced arm range of motion bilaterally (however p>0.05).

There was no significant difference in turn duration, turn velocity and number of steps in turn (p>0.05).

Based on the above findings, gait assessments using wireless sensors in the clinic could help to differentiate gait measures between ET and healthy controls and PD and healthy controls. The analysis was quick to perform in the clinic and can be utilized to track gait with disease progression. However, it seems that the gait in early PD and ET is similarly affected and it may be difficult to differentiate PD and ET by gait assessment using wireless sensors in the clinic. Interestingly we found that ET patients had increased double support time across different comparisons which suggests dynamic balance is more impaired in ET as compared to early PD. Future studies are needed to support our findings.

 

Table 2: Comparison of gait measures between different groups.

 

Gait measure

(mean)

Normative value ET (n=71) PD (n=68) HC (n=31) p value
iSAW Parameters
Gait – Lower limb speed mean (m/s) L 1.23 0.88 0.90 1.05 ET vs HC: 0.000

PD vs HC: 0.000

PD vs ET: >0.05

R 0.86 0.88 1.01 ET vs HC: 0.000

PD vs HC: 0.000

PD vs ET: >0.05

Gait – Lower limb double support (%GCT) L 18.97 24.42 23.19 21.14 ET vs HC: 0.001

PD vs HC: 0.052

PD vs ET: >0.05

R 24.59 23.58 21.59 ET vs HC: 0.001

PD vs HC: 0.061

PD vs ET: >0.05

Gait – lower limb cadence (steps/min) L 113.63 102.22 103.50 105.23 >0.05
R 102.21 103.24 104.83 >0.05
Gait – lower limb stride length (m) L 1.3 1.037 1.046 1.20 ET vs HC: 0.000

PD vs HC: 0.000

PD vs ET: >0.05

R 1.009 1.013 1.15 ET vs HC: 0.000

PD vs HC: 0.000

PD vs ET: >0.05

Gait – lower limb toe out angle (degrees) L 8.54 11.12 9.81 5.98 ET vs HC: 0.007

PD vs HC: 0.068

PD vs ET: >0.05

R 14.77 13.02 10.0 ET vs HC: 0.015

PD vs HC: 0.225

PD vs ET: >0.05

Upper limb arm velocity(degree/sec) L 180.96 165.43 151.11 184.09 ET vs HC: 0.657

PD vs HC:0.095

PD vs ET: >0.05

R 148.37 153.74 185.94 ET vs HC: 0.197

PD vs HC: 0.349

PD vs ET: >0.05

Upper limb range of motion (degrees) L 43.7 37.78 28.00 41.99 ET vs HC: 0.743

PD vs HC: 0.001

PD vs ET: 0.002

R 29.43 25.10 46.79 ET vs HC: 0.000

PD vs HC: 0.000

PD vs ET: >0.05

Turns- Duration (Sec) 2.1 2.44 2.48 2.1 ET vs HC: 0.014

PD vs HC: 0.005

PD vs ET: >0.05

Steps in turn (n) 3.7 3.81 3.91 3.4 ET vs HC: 0.169

PD vs HC: 0.051

PD vs ET: >0.05

Turn velocity 156.40 147.99 180.07 ET vs HC: 0.004

PD vs HC: 0.000

PD vs ET: >0.05