Abstract
BACKGROUND:
There are advantages to using digital textbooks, but also health concerns yet to be evaluated.
OBJECTIVE:
This study examines the use of digital textbooks’ effects on carpal tunnel, considered one of the potential health risks in students using digital textbooks.
METHODS:
Data were obtained from 43 elementary school students in the sixth grade, selected from two groups who had used digital and paper textbooks, respectively. To assess carpal tunnel function, this study performed median motor nerve and median sensory nerve conduction studies.
RESULTS:
There were no statistically significant differences between the groups, indicating that there were no functional differences related to carpal tunnel syndrome between the groups.
CONCLUSION:
Usage of digital textbook is expanding nationwide in the Republic of Korea. There is no short-term risk of carpal tunnel syndrome in this population of elementary school students.
Keywords
Introduction
Trends in today’s knowledge- and information-driven society are highly valued. A new format of textbook, which allows learning at any time and place, termed the digital textbook, has been introduced in schools. The Ministry of Educational Science and Technology (MEST) in Korea plans to expand the use of digital textbooks, developed in 2006, for all elementary, middle, and high school subjects by 2015.
Although there are advantages to the use of digital textbooks, such as portability, convenience, and vast learning resources, there are issues to be considered. Some of the anticipated problems involve the increase in computer usage due to digital textbook use, which may pose health risks to children [1, 2]. One possible health risk is video display terminal (VDT) syndrome, a general disorder found in those with extended duration of computer usage, involving the eyes, musculoskeletal tissues, skin, and the appearance of psychological stress [3]. The most common complaint among individuals with symptoms of VDT syndrome is carpal tunnel pain due to extensive keyboard and mouse use during extended computer work. According to previous research, an increase in computer usage time can potentially cause musculoskeletal discomfort [4]. Carpal tunnel syndrome (CTS), which is the most common disorder stemming from extensive use of the carpal tunnel, is caused when the wrist is pressed in local areas or when its nerves are stretched [5]. According to a 2012 report from the Korean Health Insurance Review and Assessment Service, 160,387 cases of CTS received treatment, culminating in a total cost of $33,723,602 ($1 = 1070.6 won). Among these CTS patients, children and adolescents composed 0.5% of thetotal [6].
According to a study investigating the relationship between internet addiction and VDT syndrome conducted in elementary school students, 27.9% of subjects complained of “pain in the neck, shoulder, arm, and wrist, and stiffness in the hands,” similar to that seen in CTS, and the number of complaints increased with the level of internet addiction [3]. This study also reported that the incidence of CTS is higher when the hands and wrists are used repetitively and extensively, even in elementary school students [3]. Therefore, it was concluded that additional studies were required to confirm the influence of computer usage associated with digital textbookuse on CTS.
This study measures the differences in CTS between elementary school students in digital textbook and paper textbook classes by analyzing conduction results of the median motor nerve and the median sensory nerve. This information can be used as basic data for future studies on carpal tunnel functions according to extensive digital textbook use and help to understand CTS in terms of the expansion of digital textbook usage.
Methods
Design
The purpose of the study was to compare differences in carpal tunnel function between elementary school students using digital textbooks and paper textbooks.
Participant characteristics
Research participant agreements and explanation letters for the carpal tunnel function examination were sent to the students’ homes, to be returned before the study commenced. Moreover, it included an explanation stating that the students would be visiting the Department of Rehabilitation Medicine at K University Hospital in Seoul for a carpal tunnel function examination and that a rehabilitation medicine doctor would be using an electromyography (EMG) unit to carry out the median motor nerve and median sensory nerve conduction studies. After a thorough explanation of the study, the consent form was signed and received from the students and their guardians before the examinations were conducted. On the day of the examinations, the measurement method and precautions relating to the measurements were fully explained before the study was carried out at the Department of Rehabilitation Medicine, K University Hospital.
Study participants were chosen from students in pilot schools who had used digital textbooks for over 1 year, but excluded those who had undergone surgery to implant an artificial pacemaker or had sensitivity toward electricity. In addition, students with normal upper limb muscle strength and hand sensation, and negative Phalen test and Tinel sign results were considered eligible for enrollment. Among them, 21 students from a class using digital textbooks, and 22 students from a class using paper textbooks were enrolled as study participants.
The study sample sizes were considered appropriate based on the G*Power 3.1 program calculation, which determined that the minimum sample size for each group was 21 subjects as required for t test analysis.
Evaluation method
On July 11, 2009, a nurse at K University Hospital in Seoul in the Department of Rehabilitation Medicine performed the manual muscle and sensory tests to evaluate carpal tunnel function, including the Phalen test, Tinel sign, manual muscle strength test, and a sensory evaluation of both hands. A rehabilitation medicine doctor conducted a test to examine the median motor nerve and median sensory nerve, and the results of these tests were collected for the study.
The Phalen test is considered positive if there is a tingling sensation or paresthesia on the innervated area of the median nerve after pushing the back of the hands together for 60 seconds. The Tinel sign is considered positive if there is a tingling sensation or pain around the innervated area of the median nerve when the carpal tunnel on the inside of the wrist is tapped with a reflex hammer [7]. Manual muscle testing was done by wrist flexion, palmar abduction of the thumb, and finger abduction, and the results were recorded by Medical Research Council as grade 0 (no muscle contraction) to grade 5 (normal). Sensory testing evaluated the sensation of light touch in both hands around the median and ulnar nerve regions. CTS is suspected if the results are positive, but if the results are negative, the participant is considered normal.
The rehabilitation medicine doctor performed the nerve conduction studies using a Counterpoint MK2 (Dantek®, Copenhagen, Denmark) to examine the median motor nerve and the median sensory nerve. For studies of the median nerve, an active electrode was attached to the abductor pollicis brevis, and electrical stimulation was performed 8 cm from the active electrode. The compound muscle action potential’s latency and amplitude were then recorded. For studies of the median nerve, the active electrode was attached to the third resin proximal interphalangeal joint, and electrical stimulation was performed 7 and 14 cm from the active electrode. The onset and peak latencies of the sensory nerve action potential and the amplitude between the onset and peak latencies were then recorded.
The presence of CTS was determined based on the 1999 Guidelines in Electrodiagnostic Medicine [8]. The median motor nerve is considered normal if the latency is less than 4.2 ms and if the amplitude is higher than 5.0 mV. The median sensory nerve is considered normal if the onset latency is less than 3.5 ms and the peak latency is higher than 20 μV. In addition, if the recorded peak latency of the sensory action potential of the stimulated palm is less than one-half of the peak latency of the sensory action potential of the stimulated wrist, CTS is present. The examination was carried out on both hands and was performed only after confirming a hand temperature of 34°C with a contact thermometer [7].
Data on students’ general characteristics were collected by self-report; students were asked to fill out a questionnaire on their school life, home life, and computer usage behaviors. School life was assessed by grades and satisfaction, and home life was assessed by communication time with their family. Computer usage behaviors were assessed according to location of computer usage, length of computer usage, and number of years a student had used a computer.
Statistical analysis
In this study, SAS 9.13® statistical analysis software (SAS Institute, Inc., Cary, NC) was used for data analysis. The general characteristics of the two groups were measured by descriptive statistics, while the chi square test and Student’s t test were used to verify homogeneity within the general characteristics between the two groups. A mean comparison of the nerve conduction velocity results of the digital textbook and paper textbook classes was measured using the independent sample t test, and the ratio of the changes was verified within the 95% significance level.
Results
Verification of the homogeneity of the general characteristics of study subjects
The general characteristics and the verification results of homogeneity between the two study groups are shown in Table 1. All participants were 13-year-old students in the sixth grade. Both the digital textbook and paper textbook classes had more male than female students. The students in both the digital textbook classes (30.3%) and the paper textbook (41.8%) classes answered that they frequently used a computer at home. For communication time with family per week, 37.2% of the digital textbook class answered “1–3 hours,” and 23.3% of the paper textbook class answered “more than 3 hours.” For self-evaluation of grades, 23.3% of the digital textbook class and 30.3% of the paper textbook class rated themselves as belonging to the “upper” group of the class. The average duration of computer use was 1.74 hours per day for the digital textbook class and 1.42 hours per day for the paper textbook class. The average number of years that students had used computers was 5.62 years for digital textbook class and 5.86 years for the paper textbook class. On average, students from the digital textbook class rated their satisfaction with school life as 3.67 out of 5.00; and the rating of students from the paper textbook class was 4.00 out of 5.00. Both groups were homogenous in each category, according to the homogeneity verification results shownin Tables 1 and 2.
Comparison of carpal tunnel function
Manual muscle and sensory tests
All participants showed normal strength in manual muscle testing. Sensory function was also normal in both hands.
Median motor nerve conduction study
The results of the median motor nerve (latency and amplitude) conduction study are shown in Figs. 1 and 2. The latency differences of the median motor nerve between the groups were not statistically significant (Rt: t = 1.47, p = 0.465; Lt: t = 1.03,p = 0.889).
Amplitude differences of the median motor nerve between the groups were not statistically significant (Rt: t = 0.97, p = 0.137; Lt: t = 1.77, p = 0.392).
Median sensory nerve conduction study
The results of the median sensory nerve (latency and amplitude) conduction study are shown in Figs. 3 and 4. The average peak latencies for the median sensory nerve of the wrist were within the normal range (less than 3.5 ms), and the differences between the groups were not statistically significant (Rt: t = 1.02, p = 0.965; Lt: t = 1.08, p = 0.380). In addition, when the palm was stimulated, all were more than one-half of the median sensory latency stimulated at the wrist, indicating no existence of CTS. The differences between the groups were not statistically significant (Rt: t = 1.17, p = 0.683; Lt: t = 1.03, p = 0.819).
The average median nerve amplitude difference between the groups was not statistically significant (Rt: t = 1.01, p = 0.072; Lt: t = 1.14, p = 0.074). Moreover, the average amplitudes for both stimulated palms were higher than 20 μV, indicating a normal range. The difference between the groups was not statistically significant (Rt: t = 1.11, p = 0.165; Lt: t = 1.12, p = 0.101).
Discussion
We performed a conduction study of the carpal tunnel area of the median motor nerve and median sensory nerve, comparing elementary school users of digital textbooks and paper textbooks.
There were no statistically significant differences in median motor nerve or median sensor nerve conduction detected between the digital textbook class and the paper textbook class. These results differ from those of a previous study [9], which reported that exposure to computer work can cause CTS. In addition, all of our participants exhibited normal results for the hand and upper limb muscle strength sensory evaluation, the Phalen test, and the Tinel sign. This, too, differs from other published reports. For example, Jung et al. demonstrated a significant difference in CTS symptoms according to the level of wrist-burdening work, such as “difficulty holding objects” and “relief of symptoms when hands are rubbed.” [10]. One possible explanation for the difference between our findings and those of others is that we examined school-aged children who have less exposure to daily activities involving the use of the carpal tunnel, whereas previous reports have involved adults who may be exposed to computer work for more than 8 hours per day [9], digital textbook use may have been insufficient to lead to the symptoms of CTS. Therefore, it is not feasible to compare the present study with the previous studies discussed.
Nevertheless, in light of the results of previous studies and the extended time on the computer that digital textbooks require, the issue of CTS and other problems related to extensive computer use cannot be overlooked. Past research has established a close correlation between carpal tunnel function and computer usage [3, 11]. In addition, there is a relationship between posture and duration of computer usage [12]. Classes using digital textbooks require extended computer usage, as shown by Lee et al. [11]. Pilot elementary schools using digital textbooks currently teach subjects continuously on tablet computers, as a considerable amount of time is required to set up and use the computers. Moreover, computer usage at school is associated with computer usage in the home [14]. This pattern increases total computer usage time.
Given the extended duration of computer usage associated with digital textbooks, methods to prevent potential health problems, including periodic examinations of the carpal tunnel area, are required. Specifically, because students’ increased usage influences their posture, a follow-up study is needed on the duration of digital textbook usage and posture problems. Furthermore, advice regarding the establishment of correct posture, improvements in the work environment, and utilization of assistance devices should be implemented in classes using digital textbooks. For example, results from previous studies have shown that student posture problems can cause musculoskeletal discomfort, especially in the arm area [12]. Similarly, according to Hong et al., a group of frequent digital device users reported discomfort in the wrist area [15]. Remedies include a vertical mouse, but there are also other options for reducing wrist and hand discomfort when using a computer for extended duration. Park et al. reported a statistically significant difference in wrist movement, muscle load, and subjective comfort when using an arm support made to maintain good posture during mouse use [13]. Although digital textbooks offer students various learning opportunities, a multipronged effort is needed to prevent potential health risks. Digital textbooks should not only be considered a learning tool but also a potential health problem.
This study has several limitations. First, participants were grade 6 students from pilot schools using digital textbooks; therefore, our results may have limited generalizability. In addition, the participants did not use digital textbooks long enough to influence carpal tunnel function. Despite these limitations, the present study contributes basic data on the relationship between digital textbook use and CTS. Follow-up studies are required to monitor students’ carpal tunnel health status.
Conclusions
This study was conducted to understand the functions of the carpal tunnel, which is considered a potential health problem, in students using digital textbooks. As digital textbook use is expanded in schools, it is important to prevent the potential health risks related to CTS in students. We conclude that programs and guidelines on computer using environment and carpal tunnel health, appropriate to student demand and school environments, are necessary to protect and prevent students’ wrists from harm. As CTS was not diagnosed for any student in the digital textbook or paper textbook class, these results suggest that there is no short-term risk of CTS when digital textbooks are used in place of paper textbooks. Additional research and consistent observations by professional healthcare providers responsible for student health are needed for the generalization of such results.
Funding
This study was carried out with the financial support from the Korea Education and Research Information Service of the Ministry of Educational Science and Technology in the Republic of Korea, No. CR2009-14.
Footnotes
Acknowledgments
The authors acknowledge and thank the participants who volunteered their time in the study.