An Integrated Review of Carpal Tunnel Syndrome: New Insights to an Old Problem

Abstract

Carpal tunnel syndrome (CTS) is a common entrapment neuropathy characterized by pain, numbness, and impaired function of the hand due to compression of the median nerve at the level of the wrist. Although CTS can develop from repetitive strain, injury, or medical conditions, there are also congenital and genetic risk factors that can predispose individuals to the condition. With respect to anatomical factors, some individuals are born with a smaller carpal tunnel, which increases their susceptibility to median nerve compression. Variations in specific genes, such as those encoding proteins involved in extracellular matrix remodeling, inflammation, and nerve function, have also been linked to an increased risk for CTS. CTS is associated with a high cost of health care maintenance and loss of work productivity. Therefore, it is vital that primary care physicians fully understand the anatomy, epidemiology, pathophysiology, etiology, and risk factors of CTS, so they can be proactive in prevention, diagnosing, and guiding proper treatment. This integrated review also provides insights into how biological, genetic, environmental, and occupational factors interact with structural elements to determine who is most likely to acquire and suffer from CTS. Keeping health practitioners abreast of all the factors that could impact CTS should go a long way in decreasing the health care and socioeconomic burden of CTS.

Keywords: carpal tunnel; carpal tunnel syndrome; median nerve; nerve entrapment; neuropathy.

Figure 1. Median nerve distribution in the palmar aspect of the right hand

This is an original image from the ultrasound lab department of the American University of Antigua

Figure 2. Anatomical diagram of the transverse section of a right wrist (at the distal row of the carpal bones) showing carpal tunnel and its contents

This is an original image from the ultrasound lab department of the American University of Antigua

Figure 3. Ultrasound transducer placement technique; (A) longitudinal imaging, (B) transverse imaging

This is an original image from the ultrasound lab department of the American University of Antigua

Figure 4. Ultrasound imaging of the normal carpal tunnel at the volar aspect of the wrist

On this longitudinal scan, the median nerve (*) is seen overlying the relatively hyperechoic superficial (**) and deep (***) flexor tendons of the wrist. The median nerve appears as a hypoechoic honeycomb fibrillar structure. This is an original image from the ultrasound lab department of the American University of Antigua

Figure 5. Ultrasound imaging of the normal carpal tunnel at the volar aspect of the wrist

On this transverse scan, the median nerve (*) is seen overlying the relatively hyperechoic superficial (**) and deep (***) flexor tendons of the wrist. The hypoechoic oval median nerve is located deep in the hyperechoic flexor retinaculum and has a characteristic cyst-like appearance. The tendon of flexor carpi radialis (****) is just outside the carpal tunnel. This is an original image from the ultrasound lab department of the American University of Antigua

Figure 6. Median nerve compression test

This is an original image from the ultrasound lab department of the American University of Antigua

Figure 7. Phalen's test

This is an original image from the ultrasound lab department of the American University of Antigua

Figure 8. Reverse Phalen's test

This is an original image from the ultrasound lab department of the American University of Antigua

Figure 9. Tinel sign

This is an original image from the ultrasound lab department of the American University of Antigua