AnalyzeDirect

Carpal tunnel syndrome is a painful condition of the hand caused by performing frequent or repetitive tasks. The carpal tunnel is a narrow passageway on the palm side of the wrist made up of tendons, ligaments and nerves. The median nerve, which controls sensations and movement in the thumb and first three fingers, runs through this passageway.

Carpal tunnel symptoms, which include hand numbness, tingling, feeling of pins and needles and weakness, occur when too much pressure is put on the median nerve. The assessment of the mechanical properties and elasticity of this nerve is, therefore, crucial in order to perform an accurate diagnosis of this syndrome.

Researchers from Tokyo Medical University recently developed an innovative device to measure median nerve strain, which is the change in length of this nerve after compression divided by its initial length. While traditional methods require the examiner to hold and place an ultrasound transducer at the wrist in order to apply pressure, their novel cyclic compression apparatus is no longer operator-dependent.

Being able to apply tension to the wrist through pre-determined cycles and controlled placement of the transducer, the investigators overcame several limitations, such as reproducibility of the compression-release cycles, and maintained a constant amount of pressure across all examinations. From ultrasonographic images of the carpal tunnel, Analyze software was used to calculate the area and perimeter of the median nerve. Strain measurements indicated that subjects with carpal tunnel syndrome had significantly lower median nerve strain compared to healthy controls, as the ability of the nerve to modify its length decreases with the progressive hardening of the nerve.

Findings from this study highlight that this device represents a reliable and precise method that allows for measurements of the median nerve and diagnosis of carpal tunnel syndrome.