Diagnostic accuracy of a smartphone bedside test to assess the fixation suppression of the vestibulo-ocular reflex: when

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SHORT COMMENTARY

Diagnostic accuracy of a smartphone bedside test to assess the fixation suppression of the vestibulo‑ocular reflex: when nothing else matters Florin Gandor1,2   · Manfred Tesch3 · Hannelore Neuhauser4   · Doreen Gruber1,2 · Hans‑Jochen Heinze2 · Georg Ebersbach1   · Thomas Lempert3  Received: 10 February 2020 / Revised: 20 May 2020 / Accepted: 22 May 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract Objective  Validation of a bedside test to objectify the fixation suppression of the vestibulo-ocular reflex (FS-VOR) in patients with a cerebellar syndrome and healthy controls. Methods  The vestibulo-ocular reflex and its fixation suppression were assessed by video-nystagmography (VNG) in 20 healthy subjects (mean age 56 ± 15) and 19 patients with a cerebellar syndrome (mean age 70 ± 11). The statistical cutoff delineating normal from pathological FS-VOR was determined at the 2.5th percentile of the normal distribution of the healthy cohort. VNG was then compared to a bedside test, where eye movements were recorded with a smartphone while patients were rotated on a swivel chair at a defined speed and amplitude. These videos were rated as normal or pathological FS-VOR by six blinded raters, and results compared to VNG. Results  VNG in healthy controls showed FS-VOR with a reduction of nystagmus beats by 95.0% ± 7.2 (mean ± SD). The statistical cutoff was set at 80.6%. Cerebellar patients reduced nystagmus beats by only 26.3% ± 25.1. Inter-rater agreement of the smartphone video ratings was 85%. The sensitivity of the video ratings to detect an impaired FS-VOR was 99%, its specificity 92%. Inter-test agreement was 91%. Conclusion  The smartphone bedside test is an easily performed, reliable, sensitive, specific, and inexpensive alternative for assessing FS-VOR. Keywords  Vestibulo-ocular reflex · Fixation suppression of the vestibulo-ocular reflex · Bedside test · Cerebellar syndrome

Introduction Electronic supplementary material  The online version of this article (https​://doi.org/10.1007/s0041​5-020-09947​-5) contains supplementary material, which is available to authorized users.

Fixation suppression of the vestibulo-ocular reflex (FSVOR) is a reliable clinical test of cerebellar function [1, 2], and its disturbance indicative of cerebellar pathology [1,

* Florin Gandor gandor@kliniken‑beelitz.de

Thomas Lempert thomas.lempert@schlosspark‑klinik.de

Manfred Tesch manfred.tesch@schlosspark‑klinik.de

1



Hannelore Neuhauser [email protected]

Movement Disorders Hospital, Kliniken Beelitz GmbH, Strasse nach Fichtenwalde 16, 14547 Beelitz‑Heilstätten, Germany

2

Doreen Gruber gruber@kliniken‑beelitz.de



Department of Neurology, Otto-Von-Guericke University, Magdeburg, Germany

3

Hans‑Jochen Heinze hans‑[email protected]



Department of Neurology, Schlosspark-Klinik Berlin, Berlin, Germany

4



Robert-Koch-Institut, Berlin, Germany

Georg Ebersbach ebersbach@kliniken‑beelitz.de

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