Risk Factors for Carpal Tunnel Syndrome

Pourmemari Mohammadhossein

Research output: Book/ReportDoctoral thesisCollection of Articles


Carpal tunnel syndrome (CTS) is the most common compression neuropathy in the upper limbs. Carpal tunnel release (CTR) is the most commonly performed adult surgical intervention for median nerve decompression. Work-related and individual factors are responsible for the etiology of CTS. The role of some non-occupational factors in CTS are clear, such as age, sex, and obesity. However, the magnitude of the effect of obesity on CTS remains uncertain. At present, the lifetime prevalence of CTR is not known, and the effects of some individual factors, including diabetes mellitus, hypothyroidism, rheumatoid arthritis, and osteoarthritis, on CTS have partly been explained. Furthermore, the effects of type I and type II diabetes and smoking on CTS are not understood.

The overall aim of this study is to estimate the lifetime prevalence of CTR and to identify the risk factors for CTS. Three meta-analyses and one original study were conducted to determine the role of individual factors in CTS and CTR. The metaanalyses were performed using a random-effects model. In the Finnish prospective cohort, a nationwide representative sample (N=6,256 participants) was linked to the Finnish Hospital Discharge Register from 2000 to 2011.

In the meta-analyses, only cross-sectional studies found an association between smoking and CTS. Both type I and type II diabetes were associated with CTS and CTR. Overweight and obesity were associated with CTS with a dose-response relationship. The effects of overweight and obesity on CTS were similar among women and men and were independent of the study design as well as bias and confounding. In the original study, the lifetime prevalence of CTR was 3.1%, and annual incidence was 1.7 per 1,000 person-years. Both prevalence and incidence were twofold higher in women than in men and were higher in individuals with low levels of education than in people with high levels of education. The prevalence peaked at ages 50-59 years, and the incidence peaked at ages 40-49 years. In the final full model, female sex, ages 40-49 years, education, obesity, and hand osteoarthritis were associated with the incidence of CTR.

The current study suggests that diabetes and obesity increase the risk of CTS and CTR. The basic mechanisms are not fully understood. However, fatty tissue within the carpal canal can gradually increase intracarpal pressure by reducing the carpal tunnel dimension, which leads to impaired peripheral circulation. This causes ischemia, local axonal demyelination, and axon loss. In diabetes, the activation of advanced glycation end-products causes impaired vascular nerve and increases the production of inflammatory cytokines, which resulted in median nerve neuropathy. The findings also indicate that CTR is a common surgical procedure, and 1.9% of men and 4.1% of women experience CTR during their lifetimes. Hand osteoarthritis was associated with CTR. Hand osteoarthritis has been found in severe idiopathic CTS. Therefore, osseous hypertrophy of carpal bones can result in a gradual decrease in carpal tunnel dimension.
Original languageEnglish
Place of PublicationTampere
PublisherTampere University
ISBN (Electronic)978-952-03-1393-7
ISBN (Print)978-952-03-1392-0
Publication statusPublished - 2020
Publication typeG5 Doctoral dissertation (articles)

Publication series

NameTampere University Dissertations - Tampereen yliopiston väitöskirjat
ISSN (Print)2489-9860
ISSN (Electronic)2490-0028


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