1. Electrophysiological Epidemiology of Carpal Tunnel Syndrome
FESSH June 13, 2018
Electrophysiological Epidemiology of Carpal Tunnel Syndrome
Tatsuki Ebata, Ikuo Nakai, Akira Kogure,Ken-ichiro Goto
Sakura Orthopaedic Hospital Chiba, Japan

2. T. Ebata
Objective
Carpal tunnel syndrome (CTS) is the most common upper extremity entrapment neuropathy. Nerve conduction studies are used for the diagnosis of CTS.
As the severity of CTS progresses, the nerve conduction velocity in the carpal tunnel reduces. The compound muscle action potential of the abductor pollicis brevis (APB-CMAP) demonstrates progressively increased latency and decreased amplitude. In the most advanced stages of CTS, APB-CMAP finally becomes undetectable and the motor conduction velocity cannot be measured (terminal CTS). The purpose of the present study was to investigate the epidemiology (risk factors) of CTS in relation to APB-CMAP.

3. Materials and Methods (Between 2012 and 2017)
T. Ebata
Materials and Methods
(Between 2012 and 2017)
786 hands (572 patients ) whose latencies of APB-CMAP ≥4.5
Mean age : years
Men : 136 (23.8%) Women : 436 (76.2%)
Right-handed: 542 (94.8%) Left-handed : 30 (5.2%)
The hands with undetectable APB-CMAP was defined as terminal CTS.
The binomial test, McNemar test, Wilcoxon test, and logistic regression analysis were employed for statistical analysis. A P-value of <0.05 was considered statistically significant.

4. Dominant to non-dominant ratio
T. Ebata
Results
Total: 786 hands
Men to women ratio
(P<0.01)
Dominant to non-dominant ratio
(P<0.01)
Men
191hands
(24.3%)
Dominant
446hands
(56.8%)
Non-dominant
340hands
(43.2%)
Women
595 hands (75.7%)

5. Results Terminal CTS rate Average latency of APB-CMAP
T. Ebata
Results
Terminal CTS rate
(290 patients with bilateral CTS)
Average latency of APB-CMAP
(162 patients with bilateral non-terminal CTS)
P<0.01
P<0.01
Hands ms
7.00 83
(28.6%)
6.29 52
(18.0%)
Dominant Non-dominant Dominant Non-dominant

6. Results Number of hands
T. Ebata
Results
Number of hands
Aged 60–69 years was the highest and aged 50–59 years was the second highest
Terminal CTS rate
Aged 70–79 years had the highest rates and aged 80 years and older had the second highest rates.
Hands %
222
227
29.7
26.9
27.6
22.9
101
113 71
10.9 52
5.9

7. Conclusions There are some possible risk factors of idiopathic CTS.
T. Ebata
Conclusions
There are some possible risk factors of idiopathic CTS.
Women were three times more likely to develop CTS than men. This may be because women have relatively smaller hands than men, or perhaps estrogen plays a part in the development of CTS.
Dominant hands tended to develop CTS and were more susceptible to progression than non-dominant hands. The cause of CTS may be related to overuse of the hand, as repetitive motion at work.
The age distribution curve of CTS peaked in the fifties and sixties when the most serious CTS occurred. Therefore, age is also an important factor of CTS.
A combination of these risk factors appears to contribute to the development of CTS.

8. T. Ebata
Thank you!