Wearable sensors for assessing disease severity and progression in Progressive Supranuclear Palsy

INTRODUCTION

Progressive supranuclear palsy (PSP) is an atypical parkinsonism characterized by prominent gait and postural impairment. The PSP rating scale (PSPrs) is a clinician-administered tool to evaluate disease severity and progression. More recently, digital technologies have been used to investigate gait parameters. Therefore, object of this study was to implement a protocol using wearable sensors evaluating disease severity and progression in PSP.

METHODS

Patients were evaluated with the PSPrs as well as with three wearable sensors located on the feet and lumbar area. Spearman coefficient was used to assess the relationship between PSPrs and quantitative measurements. Furthermore, sensor parameters were included in a multiple linear regression model to assess their ability in predicting the PSPrs total score and sub-scores. Finally, differences between baseline and three-month follow-up were calculated for PSPrs and each quantitative variable. The significance level in all analyses was set at ≤ 0.05.

RESULTS

Fifty-eight evaluations from thirty-five patients were analyzed. Quantitative measurements showed multiple significant correlations with the PSPrs scores (r between 0.3 and 0.7; p < 0.05). Linear regression models confirmed the relationships. After three months visit, significant worsening from baseline was observed for cadence, cycle duration and PSPrs item 25, while PSPrs item 10 showed a significant improvement.

CONCLUSION

We propose wearable sensors can provide an objective, sensitive quantitative evaluation and immediate notification of gait changes in PSP. Our protocol can be easily introduced in outpatient and research settings as a complementary tool to clinical measures as well as an informative tool on disease severity and progression in PSP.

A Convenient Prognostic Tool and Staging System for Progressive Supranuclear Palsy

Background

Progressive supranuclear palsy (PSP) causes major disability, shortens life, and as yet has no disease-modifying and little symptomatic treatment. A convenient prognostic tool is needed to assist patients, families, and clinicians in planning care.

Objectives

We calculated times to acquisition of certain disease milestones and death.

Methods

We followed a cohort of 417 patients with PSP-Richardson syndrome from 1995 to 2016, applying the Progressive Supranuclear Palsy Rating Scale (PSPRS) at each visit. We generated median times to acquisition of 13 milestones using the input variables of sex, onset age, rate of disease progression from motor symptom onset to initial visit, and PSPRS score at the baseline. Of the outcome milestones, 5 were stages of a new, provisional PSP staging system. The other 8 milestones comprised death and disabling levels of cognitive loss, gaze palsy, dysarthria, dysphagia, and gait/balance impairment.

Results

We derived median times to milestones, with 25th and 75th percentiles and 95% confidence intervals of the median for baseline PSPRS scores from 25 to 65 (scale range, 0-100). Sex and initial progression velocity significantly influenced the death milestone, but not most of the others. Median time to death ranged from 4.8 years for a man with PSPRS score of 25 and a slow progression velocity from onset to initial visit of 0.51 PSPRS points/month to 1.8 years for a woman with PSPRS 65 and rapid initial velocity of 2.25 points/month.

Conclusions

We have created a convenient, inexpensive, noninvasive reference for counseling patients with PSP-Richardson syndrome on approximate time to encountering 13 life-altering disease milestones.

Severity dependent distribution of impairments in PSP and CBS: Interactive visualizations

BACKGROUND

Progressive supranuclear palsy (PSP) -Richardson's Syndrome and Corticobasal Syndrome (CBS) are the two classic clinical syndromes associated with underlying four repeat (4R) tau pathology. The PSP Rating Scale is a commonly used assessment in PSP clinical trials; there is an increasing interest in designing combined 4R tauopathy clinical trials involving both CBS and PSP.

OBJECTIVES

To determine contributions of each domain of the PSP Rating Scale to overall severity and characterize the probable sequence of clinical progression of PSP as compared to CBS.

METHODS

Multicenter clinical trial and natural history study data were analyzed from 545 patients with PSP and 49 with CBS. Proportional odds models were applied to model normalized cross-sectional PSP Rating Scale, estimating the probability that a patient would experience impairment in each domain using the PSP Rating Scale total score as the index of overall disease severity.

RESULTS

The earliest symptom domain to demonstrate impairment in PSP patients was most likely to be Ocular Motor, followed jointly by Gait/Midline and Daily Activities, then Limb Motor and Mentation, and finally Bulbar. For CBS, Limb Motor manifested first and ocular showed less probability of impairment throughout the disease spectrum. An online tool to visualize predicted disease progression was developed to predict relative disability on each subscale per overall disease severity.

CONCLUSION

The PSP Rating Scale captures disease severity in both PSP and CBS. Modelling how domains change in relation to one other at varying disease severities may facilitate detection of therapeutic effects in future clinical trials.