The peripheral nerve is demonstrated as a reticular pattern in a transverse section at high-resolution ultrasonography (US). Its echogenicity is between that of tendon and muscle. High-resolution US applied to lesions of peripheral nerves yields impressive results in that the nerve is highly differentiated from surrounding soft tissue. In cases of trauma, high-resolution US can easily differentiate between a rupture of the nerve bundle and fibroblast infiltration that results in traumatic neuroma. In cases of inflammation or compressive syndrome, high-resolution US can easily demonstrate lesion location and cause. In the evaluation of abnormal masses, high-resolution US cannot clearly differentiate neurofibromas from schwannomas but it can clarify the relationship between tumor and neural trunk and help the clinician plan treatment strategies. The authors discuss the success that can be achieved with the application of high-resolution US in the evaluation of peripheral nerve lesions.

The purpose of this study was to evaluate the morphologic changes in the ulnar nerve in cubital tunnel syndrome with high-resolution ultrasonography. The mean values of the short axis (cm) x long axis (cm) at the arm, epicondyle, and forearm levels were 0.057 +/- 0.01, 0.068 +/- 0.019, and 0.062 +/- 0.01 in control group; 0.069 +/- 0.04, 0.139 +/- 0.06, and 0.066 +/- 0.023 in the symptomatic side in patients with cubital tunnel syndrome; and 0.063 +/- 0.029, 0.068 +/- 0.029, and 0.057 +/- 0.012 in the normal side in patients with cubital tunnel syndrome. No significant difference was found in the area (short axis x long axis) of the ulnar nerve at the arm, epicondyle and forearm levels between the left and right ulnar nerve in the control group and between the control group and the normal side in symptomatic patients. However, the mean value of the area of the ulnar nerve at the epicondyle level in symptomatic patients was significantly larger than that of the control group and that of the contralateral side in patients, and the P value was less than 0.001. High resolution ultrasonography can detect morphologic changes in the ulnar nerve accurately, and it could therefore be useful as a screening and even follow-up modality in patients with cubital tunnel syndrome.

Ultrasonography with color Doppler imaging is a good modality for characterizing most soft-tissue masses, and tumor size > 5 cm and having infiltrated margin highly suggests malignancy.

Abbreviations CDUS, color Doppler ultrasonography; MRI, magnetic resonance imaging; PSV, peak systolic velocity; RI, resistive index enign peripheral nerve sheath tumors are divided into 2 major groups: schwannomas (neurilemomas) and neurofibromas.1 Differentiation of schwannomas from neurofibromas is of relevance to surgeons because schwannomas can be easily shelled out while preserving nerve contiguity. In most neurofibromas, however, the nerve is incorporated within the mass, and the required surgery includes resection and subsequent nerve grafting to preserve and restore function. B ArticleArticle includes CME test CME CME Objective. The purpose of this study was to verify whether high-resolution and color Doppler ultrasonography could distinguish schwannomas from neurofibromas. Methods. Seventy-six tumors in 71 patients were included in this study. There were 46 patients (50 tumors) with schwannomas and 25 patients (26 tumors) with nondiffuse neurofibromas in the extremities or superficial parts of the body. Ultrasonographic examinations were performed in all patients. The tumor size, shape, location, internal echogenicity, posterior acoustic phenomenon (eg, shadowing or enhancement), capsule, relationship with the adjacent nerve, and presence of cystic components were documented. Color Doppler studies (75 lesions) and spectral Doppler studies (44 lesions) were performed. All data were analyzed with statistical software to check the significance. Results. Both tumors presented as well-defined hypoechoic nodules on ultrasonography. They were oval or lobulated, showed posterior acoustic enhancement, and were hypervascular on color Doppler ultrasonography. There was no significant difference with respect to ultrasonographic morphologic characteristics. The rates of centric, eccentric, and undetermined associations with nerves were 40%, 20%, and 40% in the schwannomas and 46.2%, 0%, and 53.8% in the neurofibromas, respectively, showing a significant difference (P = .032). There was no significant difference in the chance of cystic changes between the schwannomas (30%) and neurofibromas (23%). Conclusions. No ultrasonographic finding (gray scale, color Doppler, or spectral analysis) allows differentiation between neurofibromas and schwannomas of the extremities. A nerve eccentrically entering a mass was seen only in schwannomas, and that may allow differentiation between neurofibromas and schwannomas.

In patients with a soft-tissue mass, routine plain radiography and high-resolution ultrasonography including color Doppler ultrasonography are recommended before further evaluation with ultrasonographically guided biopsy.