Body-worn triaxial accelerometer coherence and reliability related to static posturography in unilateral vestibular failure

A. Micarelli; A. Viziano; D. Casali; F. Paolizzo; G. Costantini; G. Saggio; I. Pavone; M. Alessandrini

arxiv: 1907.11166 · v2 · pith:7DZ6VQOZnew · submitted 2019-07-22 · ⚛️ physics.med-ph · cs.IR

Body-worn triaxial accelerometer coherence and reliability related to static posturography in unilateral vestibular failure

M. Alessandrini , A. Micarelli , A. Viziano , I. Pavone , G. Costantini , D. Casali , F. Paolizzo , G. Saggio This is my paper

Pith reviewed 2026-05-24 17:48 UTC · model grok-4.3

classification ⚛️ physics.med-ph cs.IR

keywords accelerometerposturographyunilateral vestibular failurepostural swayforceplatebalance assessmentotoneurologyvestibular deficit

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The pith

Accelerometer-based sway measures show high correlation with forceplate posturography and discriminate unilateral vestibular failure patients.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper tests whether a body-worn triaxial accelerometer mounted on the lower back can serve as a practical substitute for laboratory forceplate posturography when measuring postural sway in people with long-standing unilateral vestibular failure. Thirteen UVF patients and thirteen matched controls stood still while both the accelerometer and the forceplate recorded their movements; the authors then compared four time-domain and three frequency-domain parameters extracted from each device. Pearson correlations were high across the shared measures, and two of the accelerometer parameters differed reliably between the patient and control groups on t-tests. This setup is presented as a way to bring quantitative sway analysis into routine otoneurological clinics without requiring a full forceplate system.

Core claim

Pearson product moment correlation demonstrated a high level of correspondence of four time-domain and three frequency-domain measures extracted by ACC and FBP testing; in addition, t-test demonstrated that two ACC-based time- and frequency-domain parameters were reliable measures in discriminating UVF subjects.

What carries the argument

Trunk-mounted 3-D accelerometer (Movit sensor) placed near the body center of mass, from which time-domain and frequency-domain sway parameters are extracted and compared with simultaneous forceplate recordings.

If this is right

Clinicians could add automatic sway analysis to standard balance tests for UVF diagnosis and follow-up without laboratory forceplates.
Two specific accelerometer parameters become candidate markers for separating UVF patients from healthy controls.
The method supplies both time- and frequency-domain information that can be combined with existing clinical mobility assessments.
Outcome studies of UVF rehabilitation could incorporate repeated inexpensive recordings outside the clinic.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

If the correlations hold across repeated sessions, the same sensor could track recovery or treatment response over weeks without repeated lab visits.
The approach might be extended to other vestibular or neurological balance disorders once the placement assumption is verified.
Automatic extraction of the seven shared parameters could be packaged into a simple smartphone or tablet interface for point-of-care use.

Load-bearing premise

The placement of the accelerometer on the posterior trunk is assumed to give a faithful proxy for center-of-mass motion captured by the forceplate, without separate checks on placement accuracy or signal quality in the UVF group.

What would settle it

Repeating the protocol in a new cohort of UVF patients while deliberately shifting the sensor a few centimeters from the stated placement site and checking whether the reported correlations and group differences remain intact.

read the original abstract

Due to the fact that no study to date has shown the experimental validity of ACC-based measures of body sway with respect to posturography for subjects with vestibular deficits, the aim of the present study was: i) to develop and validate a practical tool that can allow clinicians to measure postural sway derangements in an otoneurological setting by ACC, and ii) to provide reliable, sensitive and accurate automatic analysis of sway that could help in discriminating unilateral vestibular failure (UVF) patients. Thus, a group of 13 patients (seven females, 6 males; mean age 48.6 +/- 6.4 years) affected for at least 6 months by UVF and 13 matched healthy subjects were instructed to maintain an upright position during a static forceplate-based posturography (FBP) acquisition while wearing a Movit sensor (by Captiks) with 3-D accelerometers mounted on the posterior trunk near the body centre of mass. Pearson product moment correlation demonstrated a high level of correspondence of four time-domain and three frequency-domain measures extracted by ACC and FBP testing; in addition, t-test demonstrated that two ACC-based time- and frequency-domain parameters were reliable measures in discriminating UVF subjects. These aspects, overall, should further highlight the attention of clinicians and researchers to this kind of sway recording technique in the field of otoneurological disorders by considering the possibility to enrich the amount of quantitative and qualitative information useful for discrimination, diagnosis and treatment of UVF. In conclusion, we believe the present ACC-based measurement of sway offers a patient-friendly, reliable, inexpensive and efficient alternative recording technique that is useful - together with clinical balance and mobility tests - in various circumstances, as well as in outcome studies involving diagnosis, follow-up and rehabilitation of UVF patients.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

This is a small-scale empirical validation showing accelerometer sway measures track forceplate ones in UVF patients, with some group separation on two parameters.

read the letter

The paper's core contribution is the first reported head-to-head comparison of trunk-worn accelerometer sway metrics against forceplate posturography in a UVF cohort. They ran 13 patients and 13 matched controls through static stance trials, extracted four time-domain and three frequency-domain features from both systems, and report high Pearson correlations plus t-test separation on two ACC parameters. That fills the specific gap they flag in the abstract—no prior work had checked ACC validity in vestibular deficit subjects—and the setup is practical with an off-the-shelf sensor placed near the body center of mass. The direct same-subject comparison is the right design for a correspondence claim, and the stress-test note is correct that placement offset would affect both modalities symmetrically rather than create a hidden circularity. Small n=13 per group is the obvious limit on how far the discrimination result can be pushed, and the abstract gives no coefficients, p-values, or processing details, so the strength of the correlations remains hard to judge without the full tables. The work stays within static posturography and does not claim broader dynamic validity or new sensor tech. This is the kind of incremental clinical methods paper that belongs in an otoneurology or vestibular rehab journal. A serious editor should send it to review rather than desk-reject; the empirical core is clean enough to be worth referee time even if revisions are needed on sample size and reporting.

Referee Report

2 major / 2 minor

Summary. The paper claims that accelerometer-based measures from a body-worn triaxial sensor mounted on the posterior trunk show high Pearson correlations with forceplate posturography for four time-domain and three frequency-domain sway measures in 13 UVF patients and 13 controls. Additionally, t-tests indicate that two ACC parameters can discriminate UVF subjects, validating ACC as a practical tool for otoneurological assessment of postural sway.

Significance. Should the correlations and discrimination results hold upon full reporting of statistics, this study would provide evidence for using wearable accelerometers as an accessible alternative to forceplate systems in clinical settings for vestibular failure patients. The empirical design directly compares the two modalities on the same subjects, which is a strength for assessing correspondence.

major comments (2)

[Abstract] Abstract: The central claim of 'high level of correspondence' and 'reliable measures' for discriminating UVF is presented without any reported Pearson r values, p-values, effect sizes, or confidence intervals, despite these being the primary results. This omission directly limits evaluation of the strength of the empirical claims.
[Results] Results: The t-test findings for two ACC parameters discriminating UVF subjects are reported without accompanying effect sizes, exact p-values, or mention of multiple-comparison corrections across the seven extracted measures, which is relevant for a small n=13 per group.

minor comments (2)

[Abstract] Abstract: The age notation 'mean age 48.6 +/- 6.4 years' should use the standard ± symbol.
[Methods] Methods: The sensor placement description ('posterior trunk near the body centre of mass') would benefit from more precise anatomical reference points or a verification step to support replicability.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for these comments on statistical reporting. We agree that including specific values will improve transparency and allow better evaluation of our claims. We will revise the manuscript accordingly.

read point-by-point responses

Referee: [Abstract] Abstract: The central claim of 'high level of correspondence' and 'reliable measures' for discriminating UVF is presented without any reported Pearson r values, p-values, effect sizes, or confidence intervals, despite these being the primary results. This omission directly limits evaluation of the strength of the empirical claims.

Authors: We agree that the abstract should report the specific Pearson r values, p-values, effect sizes, and confidence intervals for the four time-domain and three frequency-domain measures. In the revised manuscript, we will update the abstract to include these statistics from our analysis to substantiate the claims of correspondence. revision: yes
Referee: [Results] Results: The t-test findings for two ACC parameters discriminating UVF subjects are reported without accompanying effect sizes, exact p-values, or mention of multiple-comparison corrections across the seven extracted measures, which is relevant for a small n=13 per group.

Authors: We acknowledge that the results section should include effect sizes (e.g., Cohen's d), exact p-values, and a multiple-comparison correction (such as Bonferroni) for the seven measures given the sample size. We will revise the results to add these details for the two discriminating ACC parameters. revision: yes

Circularity Check

0 steps flagged

No significant circularity; empirical statistical comparison only

full rationale

The paper reports direct Pearson correlations between time- and frequency-domain sway measures extracted from simultaneous ACC and FBP recordings on the same subjects, plus t-tests for group discrimination. No equations, derivations, fitted parameters, or self-citations appear in the load-bearing steps; the central claims are statistical outputs from measured data rather than reductions to inputs by construction. This matches the default expectation for non-circular empirical validation studies.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The central claim rests on standard statistical assumptions for Pearson correlation and t-test plus the unverified premise that trunk-mounted accelerometer placement accurately captures centre-of-mass sway; no free parameters, new entities, or ad-hoc axioms are introduced beyond these.

axioms (1)

standard math Pearson correlation and independent-samples t-test assumptions (linearity, approximate normality, independence) hold for the extracted sway measures
These tests are invoked to demonstrate correspondence and group discrimination.

pith-pipeline@v0.9.0 · 5899 in / 1259 out tokens · 42114 ms · 2026-05-24T17:48:41.814047+00:00 · methodology

Body-worn triaxial accelerometer coherence and reliability related to static posturography in unilateral vestibular failure

Core claim

What carries the argument

If this is right

Where Pith is reading between the lines

Load-bearing premise

What would settle it

discussion (0)