Smartphone-Based Self-Assessment of Objective Functional Impairment (6-Minute Walking Test) in Patients Undergoing Epidural Steroid Injection

Neurospine Neurospine 2020;17(1):136-142. https://doi.org/10.14245/ns.2040022.011 Case Report Corresponding Author Anna Maria Zeitlberger https://orcid.org/0000-0002-9837-5534 Department of Neurosurgery, Kantonsspital St. Gallen, Rohrschacher Strasse 95, 9001 St. Gallen, Switzerland E-mail: Received: January 15, 2020 Revised: February 9, 2020 Accepted: February 12, 2020 See commentary “The Advent of Smartphone Applications in Spine Surgery: Bringing the Field to the 21st Century” via https://doi.org/10.14245/ns.2040066.033. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Copyright © 2020 by the Korean Spinal Neurosurgery Society pISSN 2586-6583 eISSN 2586-6591 Smartphone-Based Self-Assessment of Objective Functional Impairment (6-Minute Walking Test) in Patients Undergoing Epidural Steroid Injection Anna Maria Zeitlberger1, Marketa Sosnova1, Michal Ziga1, Valentin Steinsiepe1, Oliver P. Gautschi2, Martin N. Stienen3, Nicolai Maldaner1,3 Department of Neurosurgery, Kantonsspital St. Gallen, St. Gallen, Switzerland Neuro- and Spine Center, Hirslanden Clinic St. Anna, Lucerne, Switzerland 3 Department of Neurosurgery, University Hospital Zurich & Clinical Neuroscience Center, University of Zurich, Zurich, Switzerland 1 2 Epidural steroid injection (ESI) represents a popular treatment option in patients with lumbar degenerative disc disease (DDD). The main objective of the article was to determine whether the 6-minute walking test (6WT) could assist in the discrimination between ESI responders and nonresponders. We used a validated 6WT smartphone application to assess self-measured objective functional impairment (OFI) in 3 patients with DDD undergoing ESI. Patient-reported outcome measures (PROMs), including the Core Outcome Measures Index and the Oswestry Disability Index, were obtained at baseline and at the 3-, 7-, and 28-day follow-up. Descriptive analyses were used to compare PROMs with OFI over time. Two patients responded well to the ESI, illustrated by clinically meaningful improvements in PROMs. This improvement was accompanied by a substantial increase in the 6WT distance (case I: 358 m vs. 517 m and case II: 296 m vs. 625 m). One patient reported only moderate improvement in leg pain and conflicting results in the other PROMs. The 6WT demonstrated a persistent OFI (487 m vs. 488 m). This patient was considered a nonresponder and underwent surgical treatment. This case series illustrates the feasibility of the smartphone-based 6WT as a tool to assess OFI in patients undergoing ESI for lumbar DDD. Keywords: Lumbar disc herniation, Objective functional impairment, Epidural steroid injection INTRODUCTION A thorough evaluation of functional impairment is essential to critically assess outcome and treatment efficacy in patients undergoing surgical or conservative treatment for lumbar degenerative disc diseases (DDDs). Traditionally, patient-reported outcome measures (PROMs) in the form of questionnaires are deployed to assess a patient’s subjective well-being, pain level, and impairment. More recently, several measures of objective functional impairment (OFI) have been described in the literature with the aim to complement PROMs by contributing an objective outcome dimension to the comprehensive patient 136 www.e-neurospine.org evaluation.2 Despite the growing number of publications in this field, to date there is no shared “gold standard” for the objective assessment of patients suffering from DDD.1 The majority of described objective measures, for example, the motorized-treadmill-test or the self-paced walk test, require considerable resources including specific equipment, trained personal and time commitment.2,3 Few objective outcome measures exist that can be selfperformed by the patient without supervision. The 6-minute walking test (6WT) was identified as a promising tool in a recent systematic review of objective outcomes in spinal surgery.1 For this purpose, a 6WT smartphone application (app) was de- Zeitlberger AM, et al. Objective Functional Impairment After Lumbar Epidural Steroid Injection veloped to be utilized by spine patients in their home environment.4 To date, there have been no reports on the use of the 6WT as an objective, self-measured functional assessment in patients undergoing lumbar interlaminar or transforaminal epidural steroid injection (ESI) for DDD. ESI represents a frequently performed nonsurgical management option in DDD even though its therapeutic benefits are debated and the diagnostic information gained from the procedure remains controversial.5-7 Whether or not a patient experienced a positive response to ESI remains difficult to determine in some settings. The 6WT may prove useful in identifying ESI responders and nonresponders. This case series presents the first experience gained while using the 6WT app in patients undergoing ESI for lumbar DDD. We compare changes in the 6WT with established PROMs and discuss the added diagnostic benefit of the 6WT. ate symptoms of leg and back pain. To assess OFI, patients were instructed to use the recently developed free 6WT smartphone app in their home environment. This spine-specific 6WT app was demonstrated to be highly reliable in settings that resemble a patient’s home environment.4 At first consultation, the 6WT app was downloaded from the Google Play Store or Apple Store (link to the 6WT app: see Supplementary material) onto the patient’s smartphone (Fig. 1). Patients received detailed instructions by their treating neurosurgeon prior to using the app. They consented that the app would measure the 6WD by accessing their smartphone’s global positioning system coordinates. Patients were instructed to select a sufficiently long (around 700 m), flat and level environment within their neighborhood, since app-based 6WD measurements had optimal reliability under those circumstances.4 Patients were then instructed to perform the 6WT twice at 4-time MATERIALS AND METHODS 1. Patient Identification We recruited 3 consecutive patients ( >18 years) scheduled to undergo transforaminal or interlaminar ESI due to lumbar DDD at the Kantonsspital St. Gallen, Switzerland, between August and September 2019. There were no drop-outs and none of the 3 patients failed to complete the follow-up. All patients were treated according to local clinical standards. 2. Subjective Outcome Assessment Patient was asked to fill out PROM questionnaires, including the core outcome measures index (COMI) back8 and the Oswestry Disability Index (ODI)9 before the intervention and at the 28-day follow-up. Participants additionally documented their leg pain on a numeric rating scale (NRS; range from 0 [no pain] to 10 [maximum pain]) for 7 consecutive days (...truncated)