# Considering the Consequences of Cybersickness in
## 2 Materials and Methods  
### Searching Process  
The INPLASY website ([[http://dx.doi.org/10.37766/inplay2023.1.0019](http://dx.doi.org/10.37766/inplay2023.1.0019)]([http://dx.doi.org/10.37766/inplay2023.1.0019](http://dx.doi.org/10.37766/inplay2023.1.0019)), accessed on 9 January 2023) has the most recent version of the systematic review procedure. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were used to conduct this systematic review [14], and the checklist is shown in Appendix B. In this article, a systematic literature search was applied to collect journal and conference articles related to cybersickness in virtual rehabilitation. This search process covered the terms as followed: VR OR virtual reality OR HMDs OR virtual environment AND cybersickness OR simulator sickness OR virtual reality sickness AND rehabilitation OR rehab OR brain injuries OR cognitive impairment OR physical inactivity. Based on the PICO model [15], the qualifying requirements were studied (participants, interventions, comparisons, and outcomes). The included papers mainly focused on the implementation of rehabilitation interventions for patients with mental or physical symptoms to alleviate their helplessness. As shown in Figure 1 and described in Section 1, the symptoms can be divided into three types according to the conditions. Pre- and post-experiments were both used to compare the differences between before and after use in the tests of these papers, in which the four attributes of SSQ were employed to measure the subjects' cybersickness scores after virtual rehabilitation.  
This research was conducted in November 2022 based on papers selected from several databases: PubMed, Web of Science, Google Scholar, and Scopus. We collected publications by searching the corresponding websites with the keywords mentioned above. The selected papers were all recent publications written in English. \"virtual reality,\" \"rehabilitation,\" \"cybersickness,\" \"Simulator Sickness Questionnaire,\" and \"immersive environment\" were among the most popular heading phrases. The selection criteria included the following: (1) the subjects utilized the virtual reality product; (2) SSQ scales were used in VR rehabilitation; (3) the papers were formal research papers. On the contrary, articles were excluded if: (1) the products were not virtual reality but mixed reality or augmented reality; (2) the papers were dissertations or reports; (3) the articles did not include SSQ scales or did not emphasize rehabilitation; (4) the standard deviations were missing in the results data.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Factors** & **Details** \\ \hline \multirow{2}{*}{Nausea} & General discomfort, increased salivation, sweating, nausea, difficulty \\  & concentrating, stomach awareness, burping \\ \hline \multirow{2}{*}{Oculomotor} & General discomfort, fatigue, headache, eyestrain, difficulty focusing \\ \hline \multirow{2}{*}{Disorientation} & Difficulty focusing, nausea, fullness of the head, blurred vision, dizzy \\  & (eyes open), dizzy (eyes closed) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Simulator Sickness Questionnaire (SSQ) factors.  
Two independent reviewers examined the research's eligibility (XL and DBL in the author list of this paper). Additionally, two reviewers separately conducted a risk-of-bias evaluation (YA and RHX in the author list of this paper). Regarding the SSQ results, the following subscale scores have fixed weights: nausea (9.54), oculomotor (7.58), and disorientation (13.92). Meanwhile, 3.74 is unweighted from the overall score. This is a crucial function in SSQ computing, which might significantly affect the study findings. The whole informative search and selection process is shown in Figure 2, together with the PRISMA principles.  
Figure 1: The main symptoms in immersive VR rehabilitation.  
Figure 2: The PRISMA flow diagram for the systematic review detailing the selection process.