Carpal tunnel syndrome (CTS) is the most commonly encountered compressive peripheral neuropathy, and the economic burden associated with its diagnosis, treatment, and indirect costs is in the billions of dollars. The typical diagnostic protocol of clinical examination and electro diagnostic nerve conduction testing is not suited to patients with early-stage CTS who retain normal nerve function. However, definitive diagnosis of early-stage CTS is highly desirable because these patients may be more receptive to conservative therapies that would decrease their long-term disability and treatment costs. Unfortunately, use of imaging methods such as MRI or ultrasound has not improved diagnosis of early-stage CTS. CTS is a compressive nerve disorder that is aggravated by hand activity. During normal, functionally-loaded hand movements, the median nerve has been shown to move dramatically through the carpal tunnel between the digital flexor tendons, thereby putting it at great risk for compression by these neighboring structures. Accumulation of these compressive insults may contribute to the development of CTS symptoms. Ultrasound is the only clinically available methodology which allows for dynamic imaging of the median nerve during all of the potential mechanical insults it may endure throughout the course of hand movement. The goal of this project is to use ultrasound to identify differences in median nerve kinematics (motion paths, speed, and movement continuity) associated with repetitive motion tasks, and to quantify differences in nerve kinematics between healthy subjects and CTS patients. The first task will be to standardize ultrasound image appearance so that measurements of nerve kinematics can be made using computer-based methods. Then, median nerve kinematics will be measured in healthy subjects performing repetitive activities. Finally, differences between median nerve kinematics in healthy subjects versus CTS patients will be identified. In the long term, measurable abnormalities in functional tissue kinematics may provide an objective diagnosis of CTS and contribute to the understanding of the underlying abnormalities in tissue mechanics that are responsible for the development of CTS.
The combination of medical and indirect costs associated with carpal tunnel syndrome ranges between $20,000 and $100,000 per affected hand, and approximately 600,000 new cases of carpal tunnel syndrome are diagnosed annually in the United States. Carpal tunnel syndrome is a disorder associated with forceful and repetitive hand movements that cause carpal tunnel tissue structures to variably compress the median nerve. The proposed work aims to measure the dynamic movement of the median nerve within the carpal tunnel using ultrasound, for the dual purposes of improving methods of early diagnosis and increasing the understanding of tissue mechanics underlying the pathology of carpal tunnel syndrome.
