Color Doppler ultrasound for evaluation of vasomotor activity in patients with carpal tunnel syndrome

Median Nerves' Electrical Activation Reduces Ipsilateral Brachial Arteries' Blood Flow and Diameter

Purpose

Our main objective in this study was to determine whether there is a difference between ipsilateral and contralateral brachial arteries' flow parameters in response to median nerves' electrical activation.

Material and Methods

The study was conducted in healthy and active subjects. The arterial diameter and flow were measured using the probe from the brachial artery. Then, the median nerve was stimulated for 5 seconds via the bipolar stimulus electrode. Arterial diameter and flow were measured once more with the Doppler transducer, which kept going to monitor continuously just after the fifth stimulus. After a week, the same subjects are invited for the purpose of measuring the contralateral brachial arteries' vasomotor response to the same stimulus.

Results

Before electrical stimulation, the median flow rate was 72.15 ml/min; after stimulation, the median flow rate was 39.20 ml/min. The drop in flow after stimulation was statistically significant (P < 0.001). While the median value of brachial artery vessel diameter before median nerve stimulation in the entire study group was 3.50 mm, the median value of vessel diameter after stimulation was 2.90 mm. After stimulation, the median nerve diameter narrowed statistically significantly (P < 0.001). As for the contralateral brachial in response to the right median nerves' activation, no significant flow or diameter change was found (P = 0.600, P = 0.495, respectively).

Conclusion

We discovered that electrical stimulation of the median nerve caused significant changes in ipsilateral brachial artery blood flow and diameter in healthy volunteers. The same stimulation does not result in flow parameter changes in the contralateral brachial artery.

Brachial arteries sympathetic innervation: A contribution to anatomical knowledge

BACKGROUND

The sympathetic nervous system makes medium and large peripheral arteries smaller to slow the blood flowing through them.

AIM

To observe brachial artery sympathetic innervation.

METHODS

We developed a neurophysiological autonomous test that measured the effects of peripheral sympathetic fibres on peripheral arteries. Our specific objective was to find the sympathetic innervation of the brachial artery. To accomplish this purpose, the brachial artery baseline diameter and flow rate were measured in the right arm of the patients. Afterwards, electrical stimulus was applied to the medial nerve for 5 s. Through electrical sympathetic activation, the vessel diameter and overall flow rate will decrease. After 7 d, a similar experiment was repeated using the ulnar nerve.

RESULTS

The differences in diameter and flow rate of the brachial artery in response to median and ulnar nerve activation were compared. In the total group, no significant difference in diameter was seen between medial and ulnar nerve stimulation (P = 0.648). The difference in absolute slowdown of flow rate between median nerve stimulation and ulnar nerve stimulation was not statistically significant for the entire group (P = 0.733).

CONCLUSION

As a target organ, the brachial artery receives an equal amount of sympathetic innervation from the median and the ulnar nerves.

Sonographic Diagnosis of Carpal Tunnel Syndrome

Diagnostic ultrasound in the diagnosis of carpal tunnel syndrome is firmly established. Preoperative evaluation is based on quantitative parameters such as measurement of the pathologically enlarged cross-sectional area of the nerve. The value of postoperative ultrasound lies in the visualization of the anatomy and the conclusions that can be drawn from it. It focuses on the semiquantitative sonographic parameters of nerve compression. Nerve lesions and persistent strictures can be visualized and clearly localized. In recurrent disease, the primary focus is to dynamically exclude postoperative scarring, which results in a reduction of nerve gliding.

Ultrasound elastography in the evaluation of peripheral neuropathies: a systematic review of the literature

Peripheral neuropathy is associated with an increase in intraneural pressure, and hence ultrasound elastography seems to be an ideal method to detect early stages of this condition based on changes in the affected nerve stiffness. The aim of this systematic review was to analyse the applicability of strain elastography (SE) and shear wave elastography (SWE) in the evaluation of peripheral nerves in patients with neuropathy of various aetiologies. Published evidence shows clearly that ultrasound elastography can accurately diagnose many types of peripheral neuropathies (carpal tunnel syndrome and other entrapment neuropathies, diabetic peripheral neuropathy and peripheral neuropathy associated with other systemic diseases), sometimes at the stages at which the condition is still asymptomatic. However, it is still unclear whether elastographic changes within the nerves precede functional anomalies detectable on nerve conduction studies. Also, relatively little is known about the relationship between the stiffness of peripheral nerves and the severity of peripheral neuropathy and its underlying condition. Based on the reproducibility data, SWE seems to be superior to SE. Nevertheless, the sources of heterogeneity in the peripheral nerve stiffness in healthy persons need to be identified, and the sets of reference values for specific peripheral nerves need to be determined. Finally, the potential confounding effect of hardening artefacts, such as bones, on the stiffness of peripheral nerves needs to be verified. After addressing all these issues, elastographic evaluation of peripheral nerve stiffness might become a reliable, easily accessible, and convenient diagnostic test performed routinely in patients with various peripheral neuropathies.

Application of ultrasound elastography for determining carpal tunnel syndrome severity

OBJECTIVE

To evaluate grey-scale and elastography ultrasound imaging findings in patients with CTS compared to nerve conductive studies.

METHOD

Sixty median nerves of 31 cases with confirmed CTS and 44 median nerves in 22 controls (healthy volunteers) who had no clinical evidence of CTS were evaluated. An expert radiologist performed all US evaluations. The RGB image is a three-dimensional matrix. A colour image RGB is an M × N × 3 array of colour pixels. The total pixels, total blue and red pixels, and blue and red indexes were compared between cases and controls.

RESULTS

Of the 60 nerves in the cases, 17 (16.3%) were mildly affected, 30 (28.8%) were moderately affected, and 13 (12.5%) were severely affected. Mean CSA, total blue pixels and blue indexes were significantly different between controls and cases with different levels of disease severity. The best cut-off point in the blue index to differentiate patients from controls was 0.1486, with a sensitivity and specificity of 80 and 70% (AUC = 0.79, P < 0.001), respectively. The best cut-off point for the red index to differentiate patients from controls was 0.1896, with a sensitivity and specificity of 70 and 55% (AUC = 0.64, P = 0.01), respectively.

CONCLUSION

Sono-elastography could be a useful diagnostic method for evaluating CTS severity in affected cases.