Application Of High Frequency Ultrasonography In Peripheral Nerve Diseases

Objective:To evaluate the role of high frequency ultrasonography in the diagnosis of non-traumatic nerve fascicle torsion of the upper extremity.Materials and Methods:15patients (age range18-42years,4female,11male) who underwent surgical treatment for nerve fascicle torsion were included in the study. There were no traumatic histories in all patients, who were affected unilaterally. Nerve fascicles of the upper extremity (brachial plexus, radial nerve, median nerve and ulnar nerve) were examined from shoulder joint to wrist joint, focusing on the distal segment of the upper arm and elbow joint. The radial nerve trunk and the proximal segment of deep branch of radial nerve were observed intensively. The location, diameter, echoic change, and peripheral anatomy structures of the nerve fascicles were observed. The location of the nerve torsion was marked by cross "x". The contralateral upper extremity was also observed as control, when necessary. In addition, five patients were examined using a commercially available clinical3.0T MRI system. The T1-weighted imaging and T2-weighted imaging, fat suppressed T1-weighted imaging, fat suppressed T2-weighted imaging and diffusion weighted MR neurography (DW-MRN) were performed. The location, diameter, signal change, and peripheral anatomy structures of the nerve fascicles were observed. The imaging characterization of non-traumatic nerve fascicle torsion in high frequency ultrasonography and MR were analyzed, and was compared with the surgical findings. The SPSS program (version13.0, SPSS, Chicago, IL, USA) was used for statistical analysis. Analysis of the paired t-test was adopted. There were significant differences between the nerve fascicle torsion and the normal nerve fascicle of contralateral upper extremity (p<0.05).Results:Both high frequency ultrasonography and MRI clearly showed nerve fascicles and peripheral soft-tissue structures.15patients were accurately diagnosed as nerve fascicle torsion preoperatively using ultrasonography and MRI. Among15 patients, there were13patients of radial nerve torsion,1patient of ulnar nerve torsion,1patient of radial nerve and median nerve torsion. In13patients of radial nerve torsion, there were deep branch of radial nerve torsion in2patients and the radial nerve trunk torsion in11patients. In15patients, there were single-segmental torsion in5patients and multi-segmental torsion in10patients.The hourglass-shaped appearance was a characteristic feature of nerve fascicle torsion, the affected segmental nerve fascicles were hypoechoic with increased diameters at ultrasonography, and had long T1and long T2signals at MRI. The mean diameter of nerve fascicle torsion at ultrasonography was0.28±0.05cm in15patients, and the mean diameter of that of the contralateral upper extremity was0.23±0.04cm. The SPSS program (version13.0, SPSS, Chicago, IL, USA) was used for statistical analysis. Analysis of the paired t-test was adopted. There were significant differences between the nerve fascicle torsion and the normal nerve fascicle of contralateral upper extremity (t=9.698,p<0.05).Conclusion:High frequency ultrasonography may be valuable in the diagnosis of non-traumatic nerve fascicle torsion of the upper extremity, there was important value in clinical preoperative evaluation and surgical intervention. Objective:To evaluate the role of high frequency ultrasonography in the diagnosis of peripheral nerve tumor.Materials and Methods:46patients (age range2-76years, mean age37.8years) of peripheral nerve were retrospectively studied, including18females and28males. There were single tumor in36patients and multiple tumors in10patients. The tumors were examined by high frequency ultrasonography. The tumor location, diameter, echoic change, and peripheral anatomy structures of the tumors were observed. The contralateral extremity was also observed as control, when necessary. In addition,11patients were examined using a commercially available clinical3.0T MRI system. The T1-weighted imaging and T2-weighted imaging, fat suppressed T1-weighted imaging and fat suppressed T2-weighted imaging were performed. The location, diameter, signal change, and peripheral anatomy structures of tumors were observed.Results:Both high frequency ultrasonography and MRI clearly showed tumors and peripheral soft-tissue structures. There were29schwannomas,8neurofibromas and9fibrolipomatous hamartomas. In10cases of multiple tumors, they were all schwannoma. Concerning tumor location, there were17cases of median nerve,13cases ulnar nerve,6cases common peroneal nerve,5cases tibial nerve,4cases cutaneous nerve and2cases brachial plexus.Normal peripheral nerves on ultrasonography appeared as hypoechoic nerve fascicles and hyperechoic connective tissue. In the transverse plane, the peripheral nerve was relatively hyperechoic compared with surrounding muscle tissue. In the longitudinal plane, the peripheral nerve had a linear fascicular appearance. The peripheral nerve location was relative constant by real-time observation, not with muscles, tendons and ligaments movement.Schwannoma on ultrasonography appeared as low echo mass with clear boundary, the tumors of the upper edge and lower edge were associated with nerve, like a rat-tail appearance. There were multiple cystic and hemorrhagic no-echo area in tumors, there were rich blood flow signals in Schwannoma. The sonography of multiple schwannomas appeared as beaded nodular along the nerve.The features of neurofibroma sonography were divided into three types: localized type, plexiform type and diffuse type. The localized type was the most common, which sonography was similar to Schwannoma. The plexiform type and diffuse type was relatively rare. The plexiform type of neurofibroma appeared as multiple hypoechoic nodules, which was bead-like change and without obvious boundary. The diffuse type appeared as subcutaneous fascia layer diffuse thickening, structure disorder, diffuse distribution of plexiform hypoechoic nodules, which was similar to lymphedema.The fibrolipomatous hamartoma of peripheral nerve was showed expansive growth. The hyperechoic fat tissue and hypoechoic nerve fibers were alternated with one and another, the peripheral nerve was lotus-like appearance in the transverse plane, and cable-like appearance in the longitudinal plane. There were no blood flow signals in nerves.Conclusions:High frequency ultrasonography may be valuable in the diagnosis of peripheral nerve tumors, thus helpful in clinical preoperative evaluation and surgical intervention.