Extended Abstract
1. Introduction
Carpal Tunnel Syndrome (CTS) is caused by compression of the median nerve as it travels through the wrist at the carpal tunnel [1]. This syndrome is the most common compression neuropathy in the upper extremities [2]. It is a debilitating disease of the hand, and if left untreated, it can damage the median nerve, resulting in impaired hand function [4]. In general, there are a variety of reasons for CTS, but high force, high-repetition jobs, prolonged positioning, and vibration are the most common causes [8]. Approximately 50% of CTS are due to work activities [9]. In the hairdressing profession, due to the repetitive movements, long-term work in standing positions and incorrect posture, there is a possibility of musculoskeletal disorders such as CTS [10]. Working with the arms at shoulder height is often associated with neck and shoulder pain as well as circulatory problems, the pathophysiological mechanisms and possible causes of which have been described in several systematic review studies [12]. Since few studies have been conducted in this field in Iran, the present study aimed to investigate the prevalence of CTS among male hairdressers in Bojnourd, Iran.
2. Participants and Methods
Of all the hairdressers in the study, 38 had CTS symptoms such as numbness of the fingers, and underwent Phalen’s and Tinel’s tests, 22 of whom tested positive. As a result, they were referred to a rehabilitation specialist for electrodiagnostic studies. Electrodiagnostic studies were performed by the Synergy device (Medelec, UK). The device settings are as follows: Pulse duration= 0.2 ms, stimulus speed= 2ms/division, Sensitivity= 20 μv/division for sensory test and 1 v/division for motor test, filter settings= 3 Hz to 10 kHz for motor test and 10 Hz to 3 KHz for sensory test. The motor component of the median nerve was stimulated orthodromically and its sensory component was driven antidromically. 
The latency (the time from the onset of stimulation to the wave onset or peak) was determined. In determining the Compound Muscle Action Potential (CMAP) of the median nerve, the latency onset and for the Sensory Nerve Action Potential (SNAP) of the median nerve, the latency peak were also calculated. In evaluating the height of the nerve conduction, the peak-to-peek amplitude (in microvolt) was calculated based on the microwave wavelength. The median nerve velocity was calculated based on the distance between proximal and distal regions of stimulation in centimeters. Collected data were analyzed in SPSS V. 22 software by using descriptive statistics such frequency and percentage by considering a significance level of P<0.05.

3. Results
Among the 109 hairdressers participated in the study, 22 had met clinical and electrodiagnostic criteria for CTS (20.8%). Of these, 45.45% had mild (n=10), 31.81% moderate (n=7) and 22.72% severe CTS (n=5). Therefore, the highest CTS prevalence was observed in hairdressers with mild form. In general, the prevalence of CTS in subjects was 20.8% (Table 1). The most common complaint in patients was finger numbness (88.8%) and the most common clinical findings were positive Tinel (58.9%) and Phalen (50.9%) tests. Moreover, the simultaneous involvement of two hands (bilateral) was observed in 5 subjects with this syndrome (22.72%).
4. Discussion
The aim of this study was to investigate the prevalence of CTS in male hairdressers in Bojnourd, Iran which was estimated at 20.18%. Many studies have been conducted on the prevalence of CTS in different countries, and the results of these studies have been consistent with or against the results of present study. Perhaps the reasons for discrepancy include differences in the number of samples, gender, economic status, age, literacy, employment, living area (rural or urban). For example,  Atroshi et al. conducted a study on 2,466 American adults in 1999 and found that the prevalence of CTS was 2.7% [17], while in the study by Dekrom et al. on Swedish men, its prevalence was reported 6% [18].
5. Conclusion
In this study, 22 of 109 hairdressers had CTS; 10 had mild syndrome, 7 had moderate syndrome, and 5 severe syndrome. Hairdressers with severe CTS felt discomfort in both hands, while others felt numbness and pain only in their dominant hand. The most important principle in avoiding such syndromes is prevention. Prevention is the main goal of reducing labor loss and the need for surgery. It includes reducing forces, reducing activities in jobs that require repetition of wrist and hand movements, changing job, changing work tools, and so on. In this regard, it is recommended that in future studies, by teaching hairdressers on the correct methods of job performance and improving their working conditions and the impact of these factors in reducing musculoskeletal disorders, especially CTS, and performing exercises for the wrists and hands, their status should be reviewed and researched again after one year.


Ethical Considerations
Compliance with ethical guidelines
In this study, all tests were conducted according to the guidelines of American Board of Electrodiagnostic Medicine (ABEM). All subjects signed a consent form to participate in the study.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Authors' contributions
Conceptualization: Ali Roshandel Hesari and Mohsen Tavakoli; Methodology, Investigation, Initial Draft Preparation, Editing and Review: Ali Roshandel Hesari; Validation, Resources, Data Analysis, and Visualization: Mohsen Tavakoli and Ali Kamali; Supervision and Project Administration: Mohsen Tavakoli; Funding acquisition: All Authors.
Conflicts of interest
The authors declared no conflict of interest.
Acknowledgements
The authors would like to thank the Hairdressers’ Association in Bojnourd city, the hairdressers participated in the study, and all those who helped us in conducting this research.