Ultrasonography of the Peripheral Nerves of the Forearm, Wrist and Hand: Definition of Landmarks, Anatomical Correlation and Clinical Implications.

BACKGROUND: Peripheral nerve pathologies of the upper extremity are increasingly assessed by high-resolution ultrasonography (HRUS), yet rapid identification of nerve segments can be difficult due to small nerve diameters and complex regional anatomy. We propose a landmark-based approach to speed up and facilitate evaluation and intervention in this region. METHOD: Relevant landmarks and section planes for eleven nerve segments of the forearm, wrist and hand were defined by ultrasonography in cadaver arms before cryosection and topographical neurovascular preparation. Information on all nerve segments and a pictorial guide including anatomical cross-sections, topographical preparations and HRUS images are provided. The identification rates of these nerve segments were then assessed in 20 healthy volunteers. RESULTS AND CONCLUSION: Sonographic landmarks and guidelines for the rapid identification and assessment of nerves of the forearm, wrist and hand are presented in pictorial and tabular form, including discussion of normal variants. Utilizing this overview should facilitate training, diagnostic examinations and intervention for nerves of the upper extremity. KEY POINTS: · High-resolution ultrasound enables assessment of peripheral nerves of the forearm, wrist and hand.. · A landmark-based approach can facilitate and speed up nerve evaluation in these regions.. · High detection rates could be reproduced using the proposed landmark-based approach.. CITATION FORMAT: · Gruber L, Loizides A, Peer S et al. Ultrasonography of the Peripheral Nerves of the Forearm, Wrist and Hand: Definition of Landmarks, Anatomical Correlation and Clinical Implications. Fortschr Röntgenstr 2020; 192: 1060 - 1072.

High resolution ultrasound in posterior interosseous nerve syndrome.

INTRODUCTION: Posterior interosseous nerve (PIN) syndrome is a rare compression neuropathy of the PIN in the region of the supinator muscle, most common by the arcade of Frohse. We aimed to specify ultrasonographic findings in patients with PIN syndrome in comparison to healthy volunteers. METHODS: Ultrasound images and clinical data of 13 patients with PIN syndrome confirmed by neurological examination and electrophysiological testing were evaluated retrospectively. Anteroposterior nerve diameters measured at the arcade of Frohse were compared with those of 20 healthy volunteers. The echotexture and the presence of a caliber change of the PIN were additionally assessed. RESULTS: Enlargement of the PIN was seen in all patients with PIN syndrome, but not in volunteers (statistically significant difference in mean diameter P < 0.05). Furthermore, edema and caliber change of the PIN were present in all patients. CONCLUSIONS: High-resolution ultrasound allows for differentiation between patients with PIN syndrome and healthy volunteers.

Ultrasound-guided injections in the middle and lower cervical spine.

Injection therapies play a major role in the treatment of cervical pain and are becoming integral parts of a multidisciplinary approach in treatment and rehabilitation of such patients. Pararadicular- and facet-joint injections in the cervical spine are preferentially performed under computed tomography (CT) or fluoroscopy-guidance. In this article we present an alternative, simple and easy to learn step by step US-guided technique for injection therapy in the cervical spine.

Ultrasound of the median arcuate ligament syndrome: a new approach to diagnosis.

INTRODUCTION: The currently accepted pathophysiological concept behind median arcuate ligament syndrome (MALS) is vascular compromise by atypically positioned median arcuate ligament. Despite many articles on MALS, only sparse data on the outcome in general and the rather poor outcome after intervention have been reported and this makes at least questionable the current concepts of the underlying disease. MATERIAL AND METHODS: A total of 364 patients with suspected celiac trunk pathology underwent a standardized ultrasound assessment procedure: suspected diagnostic features for MALS such as typically elevated peak flow velocities (PV) in the celiac trunk or atypical celiac trunk deflection-angles (DA) were defined in patients and in 20 matched volunteers. RESULTS: All the 6 retrospectively clearly diagnosed MALS-patients as well as 40% (8/20) of volunteers presented a DA of over 50°. MALS-patients presented a mean inspiratory PV of 172cm/s (+/- 40.9 cm/s), a mean expiratory PV of 425cm/s (+/-130.1 cm/s) with a PV-amplitude of 249.1% (+/-68.9%). Volunteers presented a mean inspiratory PV of 126.9cm/s (+/-42 cm/s), a mean expiratory PV of 209.9cm/s (+/-80.1 cm/s) with a PV-amplitude of 169.4% (+/-54.3%). CONCLUSIONS: The combination of a maximum expiratory PV of over 350 cm/s and a DA higher than 50° seems to be a most reliable indicator for MALS in this small series of patients. Based on these data we propose that functional ultrasound should be the first line in screening for MALS. However, a clear pathophysiological definition of MALS remains still obscure.

Perfusion pattern of musculoskeletal masses using contrast-enhanced ultrasound: a helpful tool for characterisation?

OBJECTIVE: We report 54 patients with histologically evaluated musculoskeletal masses who underwent grey-scale and contrast-enhanced ultrasound (CEUS), followed by ultrasound-guided biopsy. We hypothesise that the definition of a CEUS-based enhancement pattern improves the characterisation of tumour malignancy. METHODS: Fifty-four patients with soft-tissue masses were examined according to our standardised ultrasound procedure. After CEUS, quantitative and qualitative perfusion analyses were performed and each mass was assigned to one of four preliminarily defined perfusion patterns (P1-P4). Additionally, mass size and localisation were recorded. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) in the definition of malignancy were calculated for relevant combinations of localisation, size and perfusion pattern. RESULTS: The single event probability for malignancy was 0% for the P1 and P4 perfusion patterns, and 60% for P2 and 80% for P3. The best combined sensitivity (89%) and specificity (85%) was achieved in a "three-feature combination" of size >3.3 cm, mass location below the superficial fascia and either P2 or P3 perfusion pattern with a PPV of 86% and NPV of 88%. CONCLUSION: The proposed definition of perfusion pattern types with CEUS may serve as a new and reliable diagnostic tool for distinguishing malignant soft-tissue masses from their benign counterparts. KEY POINTS: • CEUS can assess "tumour perfusion". • Four typical perfusion patterns are seen on CEUS of musculoskeletal masses. • Knowledge of tumour size, localisation and perfusion pattern can help patient management.

Contrast Enhanced Ultrasound of the lower limb deep venous system: a technical feasibility study. Technical innovation.

BACKGROUND: A clear diagnosis of deep venous thrombosis (DVT) is still challenging: many patients with unclear compression/duplex-sonography undergo a trial of anticoagulative treatment with the immanent risk of systemic hemorrhagic complications. As contrast enhanced ultrasound (CEUS) has the potential to visualize the blood pool, we conducted this pilot study to determine its potential in the characterization of the deep venous system of the lower limb. MATERIAL AND METHODS: CEUS was performed with a 9-3 MHz broadband linear transducer (iU22®, Philips, USA) after the standard-application of a second-generation contrast agent (SonoVue®, Bracco, Italy) in three healthy volunteers. Transverse US-scans were performed for depiction of the fibular-, posterior tibial-vein group, the popliteal, femoral, the external iliacal and the inferior caval vein at defined levels. RESULTS: On our three volunteers the intended segments of the deep venous system of the lower limb were visualized clearly between 45 and 350 seconds by CEUS. The continuous proximal ward scanning demonstrated the venous topography up to the external iliac veins. DISCUSSION AND CONCLUSIONS: These preliminary results show that the use of CEUS is at least promising in the detection and characterization of the deep venous system of the lower limb. This should be pathbreaking, especially in patients with e.g. high Body Mass Index, local edema, diffuse inflammation etc. undergoing sonographic assessment for suspected deep vein thrombosis not definable by complete compression venous ultrasound or duplex ultrasound.

Ultrasound guided core needle biopsy of soft tissue tumors; a fool proof technique?

AIM: To assess technical and lesion related factors affecting the quality of ultrasound guided core needle biopsy (CNB) of musculoskeletal soft tissue tumors. MATERIALS AND METHODS: Data of 223 CNBs were evaluated in a retrospective study. Diagnostic yield was calculated for all lesions on the basis of lesion location (extremity/torso), examiner, biopsy needle gauge/length and number of acquired samples. Diagnostic accuracy was calculated for surgical lesions (n= 113) based on final specimen histology. Chi-square test based Phi-coefficient calculations were performed to search for associations between each factor and diagnostic yield. RESULTS: Overall diagnostic yield was 94.6%. There was no significant difference in diagnostic yield between specialist biopsies (96.8%) and resident biopsies (93.1%), between lesions located in the extremities (94.9%) and lesions in the torso (93.8%) and on the basis of needle gauge or number of acquired cores. Diagnostic accuracy was 100% for surgical lesions. The only factor influencing the quality of CNB was lesion composition (repeat biopsies in myxoid and/or inhomogeneous lesions). CONCLUSION: The most important aspects to achieve constant high quality results with ultrasound guided CNBs in the work-up of musculoskeletal soft tissue tumors are expertise concerning identification and targeting of viable tumor components and strict adherence to a quality controlled biopsy procedure. Once this is achieved, technical factors have almost no effect on the quality of CNB.

The "dark tendon sign" (DTS): a sonographic indicator for idiopathic trigger finger.

Although the diagnosis of "idiopathic trigger finger" (stenosing tenovaginitis) is normally based on clinical examination alone, to date there is no reliable evaluation defining this idiopathic disease beyond an exclusion of secondary causes or an unnecessary sonographic certification of high-grade impairment. By standardized assessment of 32 patients who retrospectively fulfilled the study inclusion criteria and their comparison to a matched group of volunteers, we defined the diagnostic efficiency of the here newly proposed sonographic dark tendon sign (DTS) alone, of impaired tendon gliding alone and the combination of these two features. Pulley thickness in patients and volunteers was significantly different. The combination of clinically impaired tendon gliding plus the DTS reached a sensitivity and diagnostic efficiency of 100%. We propose this diagnostic combination as the new first line assessment features for the quick definition of idiopathic stenosing tendovaginitis during daily routine

Ultrasound-guided injections in the lumbar spine.

Injection therapies play a major role in the treatment of low back pain and radiculopathy and are becoming integral parts of a multidisciplinary approach in treatment and rehabilitation of patients with pain. Pararadicular- and facet-joint injections in the lumbar spine are preferentially performed with computed tomography (CT) or fluoroscopy-guidance. In this paper we present an alternative, simple and easy to learn US-guided technique for injection therapy in the lumbar spine.

The validity of ultrasonographic assessment in cubital tunnel syndrome: the value of a cubital-to-humeral nerve area ratio (CHR) combined with morphologic features.

Diagnosis of a typical idiopathic cubital tunnel syndrome (CuTS) is straight forward but the work-up of mild forms is clinically challenging. The diagnostic value of high-resolution ultrasound (HRUS) relying solely on nerve measurements is doubtful. Additional textural analysis of the nerve may possibly overcome this drawback. Thirty-eight prospectively enrolled patients with idiopathic CuTS and 23 healthy volunteers underwent standardized HRUS. A cubital-to-humeral nerve area ratio (CHR) was calculated and the texture of the most swollen nerve segment assessed. CHR was significantly different among patients and volunteers (p<0.001) but with a marked overlap. Combination of at least partial inner fascicular masking plus a CHR>1.4 showed a positive linear coherence with idiopathic CuTS at a specificity>95% and a PPV>90%. Thus, the combined textural analysis and CHR calculation seems a powerful tool for the sonographic diagnosis of idiopathic CuTS.

State-of-the-art HR-US imaging findings of the most frequent musculoskeletal soft-tissue tumors.

High resolution ultrasound (HR-US) including color Doppler ultrasound (CD-US), power Doppler ultrasound (PD-US), and spectral wave analysis (SWA), is a broadly available, non-invasive and relatively low-cost modality without ionizing radiation. It is increasingly used for initial assessment of an ambiguous musculoskeletal soft-tissue lesion and for sonographically guided core biopsy. The aim of this review is to provide sonographic findings of the most frequent benign and malign soft-tissue lesions. By this essay, we can show that combined with clinical features, with information on tumor-localization and patient age, many musculoskeletal lesions may be successfully characterized by HR-US. In contrast, a mere morphologic assignment of some fibrous tumors and malignant lesions remains often impossible; however, certain CD-US signs such as anarchic vascular architecture or arteriovenous shunting may be very helpful indicators for malignancy. HR-US offers a simple, quick, and reliable first-line examination of musculoskeletal soft-tissue lesions and may have an important role in the diagnostic work-up followed by magnetic resonance or multimodality imaging and guided core biopsy.

Practical experience with sonographically guided phenol instillation of stump neuroma: predictors of effects, success, and outcome.

OBJECTIVE: Phantom limb pain and stump pain frequently occur after limb amputation, and stump neuromas play an important role in generation of the pain. The purpose of this study was to evaluate the effects of a previously described optimized procedure for sclerosis of painful stump neuromas under real-time high-resolution sonographic guidance. SUBJECTS AND METHODS: In this prospective study, neurosclerosis was performed on 82 patients by means of high-resolution sonographically guided injection of up to 0.8 mL of 80% phenol solution according to a standardized protocol. RESULTS: During treatment all patients had marked improvement in terms of reduction of pain measured with a visual analog scale. Twelve (15%) of the subjects were pain free after one to three treatments, nine of the 12 achieving relief with the initial instillation. At 6-month follow-up evaluation, 52 patients assessed their present pain quantity with a simplified three-step score. Twenty (38%) of the 52 patients reported almost unnoticeable pain, and 33 (64%) reported pain equal to the minimum reached during therapy. In 18 (35%) of the 52 patients, the incidence of painful periods had markedly decreased. The neurosclerosis procedure had a low complication rate (5% rate of minor complications, 1.3% rate of major complications). CONCLUSION: The high-resolution sonographically guided neurosclerosis procedure had a significantly better outcome than other documented treatments. Sonographically guided neurosclerosis should be included in the management of chronic phantom limb and stump pain.

High-resolution ultrasound of peripheral neurogenic tumors.

Peripheral nerve tumors are not frequent, but due to their association with a nerve they are somewhat special. They may be encountered incidentally during evaluation of a soft-tissue mass or when a nerve lesion is clinically suspected and the recognition of such a lesion and its differential diagnosis is key for successful therapy and patient prognosis. As sonography is often the first line modality in the work-up of a soft-tissue mass, the sonographer should be aware of the typical features of such lesions in order to arrive at the correct diagnosis, and this article tries to give an overview of the histological subtypes of peripheral nerve tumors and their sonographic characteristics.

Leg edema formation and venous blood flow velocity during a simulated long-haul flight.

INTRODUCTION: Long-distance traveling in a sitting position may be associated with an increased incidence for venous thromboembolism. As major contributing factors immobility and compression of leg veins are discussed. At present no studies have been performed measuring the time course of lower limb blood flow, leg volume and leg tissue thickness during a long-haul flight. MATERIALS AND METHODS: We measured limb volumes (plethysmographic method), lower leg tissue thickness and lower limb venous hemodynamics before, during and after 10 h sitting in modern aircraft chairs under normobaric hypoxia in healthy volunteers (n=12). RESULTS: Lower leg volume was already significantly increased after 4 h sitting (+109 ml) reaching its maximum after 10 h (+145 ml). These changes were accompanied by an increased body weight, total body water, extracellular water and tissue thickness of the tibia. No significant changes were measured for leg vessel cross-section diameters and maximal flow velocities in superficial femoral veins. After 10 h sitting core temperature, overall surface temperature and skin temperatures in front of the tibia were significantly increased. All parameters returned to baseline one day after sitting. CONCLUSIONS: Prolonged sitting in modern aircraft seats is associated with a remarkable fluid accumulation in the lower legs which mainly occurred during the first hours. These fluid shifts were independent of lower limb venous hemodynamics and vessel cross-sectional diameters.

High-resolution ultrasound of the supraclavicular brachial plexus--can it improve therapeutic decisions in patients with plexus trauma?

Patients with major traumatic brachial plexus lesions benefit from early surgery, but they are seldom isolated by today's diagnostic workup. Subjects with ambiguous findings after such workups usually undergo a trial of conservative treatment and those without improvement delayed surgery. Our study focuses on this problem. Hence, the purpose of this study was to evaluate the impact of high-resolution ultrasound (HR-US) on patient recruitment for non-delayed surgery. Twelve patients after blunt shoulder trauma and standardized HR-US assessment who underwent plexus surgery were included in this prospective observational study. Thereby, a total of 168 plexus elements were evaluated. All findings were compared to electrophysiological data if available and tested statistically against the gold-standard, i.e., surgical validation. Major plexus lesions were correctly detected by HR-US in nine patients (20 plexus elements). In two patients (five plexus elements), the lesion was underestimated by HR-US in relation to the gold standard (surgical inspection). Our analysis showed a high positive (1.0) and an acceptable negative predictive value (0.92) for the grading of traumatic plexus lesions with HR-US. Based on HR-US findings alone, 9 of 11 patients with objective major lesions would have undergone early surgery. In conclusion, HR-US proved a valuable tool for the triage of patients with traumatic lesions into surgical and non-surgical candidates.

Peroneal nerve palsy associated with knee luxation: evaluation by sonography--initial experiences.

OBJECTIVE: Traumatic knee dislocation needs immediate surgical repair to restore joint function. A concomitant traction injury of the peroneal nerve is reported to exist in up to 25% of cases and is often overlooked initially. In patients with major nerve lesions, immediate surgical nerve repair might be necessary to avoid irreversible loss of neural function. In the present study, we tried to evaluate whether sonography is a valuable tool for identification of nerve pathology that warrants surgical intervention. SUBJECTS AND METHODS: In this prospective study, both peroneal nerves in nine patients with one-sided peroneal nerve palsy after closed knee luxation and the peroneal nerves of 11 healthy volunteers were investigated with sonography. Using statistical analysis, we tried to define the comparability and significance of the findings. RESULTS: The mean cross-sectional area of healthy peroneal nerves in the genicular region was 0.18 cm2 (SD, 0.07 cm2). Impaired nerves were significantly discerned because of their increased cross-sectional area at the level of the injury (mean cross-sectional area, 0.7 cm2; SD, 0.46 cm2; p < 0.05). Identification of caliber changes and depiction of at least one nerve stump were found to be the most specific criteria for the definition of a major neural lesion. The ability of sonography to provide additional information about surrounding soft-tissue impairment (scar tissue and hematoma formation) proved helpful. CONCLUSION: Sonography allows radiologists to visualize neural and extraneural pathology and to define the exact level and extent of lesions. Thus, it may be a valuable adjunct in the decision of whether surgical intervention is necessary.

Detection and characterization of perianal inflammatory disease: accuracy of transperineal combined gray scale and color Doppler sonography.

OBJECTIVE: To evaluate the accuracy of transperineal gray scale and color Doppler sonography for the detection and characterization of perianal inflammatory disease with surgical correlation. METHODS: Eighty-seven patients with suspected perianal inflammatory disorders underwent transperineal gray scale and color Doppler sonography with a linear 4- to 7-MHz transducer that was used to scan the entire perianal region for the detection of suspected inflammatory disorders. Each detected inflammatory disorder was evaluated to determine its morphologic characteristics and extent. Color Doppler sonography was applied to assess the presence of increased vascularity in the perianal region. In comparison with surgical findings, the diagnostic performance of transperineal sonography was assessed by means of receiver operating characteristic analysis for lesion detection and the Spearman rho test for lesion characterization. Logistic regression analysis was used to assess whether increased perineal vascularity was a predictive factor of perianal inflammatory disease. RESULTS: Seventy-seven perianal inflammatory disorders were confirmed in 62 patients. Gray scale sonography achieved a significantly good performance in the detection (area under the curve = 0.86; P < .001) and characterization (r = 0.65; P < .001) of perianal inflammatory disease. For the detection of perianal fistulas and abscesses, sensitivity was 100% for both, and specificity was 100% and 94%, respectively. With the use of color Doppler sonography, the diagnostic confidence increased slightly (area under the curve = 0.89) but significantly (P = .002). Logistic regression analysis identified hypervascularity at the periphery of a perianal lesion as a significant independent predictor of an inflammatory disease. CONCLUSIONS: Combined gray scale and color Doppler sonography enables a high detectability rate and comprehensive characterization of perianal abscesses and fistulas.

Sonographic evaluation of primary peripheral nerve repair.

OBJECTIVE: This feasibility study was undertaken to define the potential of sonography for the follow-up evaluation of patients with surgical repair after nerve transection and persistent impairment of nerve function. METHODS: Nineteen patients with primary repair of a transected peripheral nerve because of direct trauma or complex fractures were evaluated with sonography. All patients had persistent clinical symptoms and neurologic signs of impaired nerve function. In 11 patients who underwent second operations, the intraoperative findings were correlated with those of sonography. RESULTS: Reliable identification of repaired nerves with sonography was feasible in all patients. However, in some cases, sufficient visualization of the site of nerve coaptation was problematic because of extensive scarring. Sonographic findings included the appearance of partial discontinuity of nerve fascicles, detection of neuromas, and compression of nerves by overlying scars. Surgical correlation with sonographic findings was excellent for neuroma detection; however, definition of nerve continuity on sonography was sometimes impaired by scarring. CONCLUSIONS: Sonography has a high potential for follow-up examinations of peripheral nerves in relation to previous nerve repair in patients with persistent neurologic signs and symptoms of nerve impairment. Sonography may help in decisions for follow-up surgery by identifying lesions such as neuromas in continuity or discontinuous nerve elements--lesions that will possibly benefit from a second look.