Ultrasound imaging of the transversus nuchae muscle: a potential entrapment site for the lesser occipital nerve.

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Statin-Induced Necrotizing Autoimmune Myopathy: Case Report of a Patient under Chronic Treatment.

Introduction: 3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) inhibitors are widely used worldwide to treat dyslipidaemia and prevent cardiovascular events. Statins can cause a wide variety of muscle injuries ranging from myalgia to severe rhabdomyolysis. In most cases, these symptoms are mild and self-limiting and do not require specific treatment besides drug withdrawal. Statin-induced autoimmune necrotizing myopathy (SINAM) is a rare but potentially fatal complication, characterized by the subacute onset of progressive proximal muscle weakness and considerably high creatine phosphokinase (CK) levels in patients exposed to statins. The diagnosis is supported by the presence of antibodies HMGCR, which allows the differentiation from other forms of necrotizing autoimmune myopathies. Symptoms usually progress even after statin discontinuation and can determine severe muscle damage. Summary. We describe the case of a 77-year-old man who developed SINAM after 5 years of statin use. He suffered from muscle functional impairment mainly involving proximal lower limb muscles which progressed to the point that he almost became bedridden. Initial treatment with prednisone alone was not effective, and he required a combination therapy with steroids, methotrexate, and intravenous immunoglobulins. After 5 months of therapy and rehabilitation, he showed complete laboratory response and muscle strength recovery. Conclusion: Recognizing SINAM is paramount in order to promptly start treatment and avoid permanent muscle damage. Using a combination therapy from the beginning could contribute to a better outcome. Prompt statin cessation, categorization of the muscle disease by autoantibody testing, imaging, and histology, exclusion of malignancy, and anti-inflammatory therapy with corticosteroids, antimetabolites, immunoglobulins, and in some cases rituximab are currently accepted approaches to this entity.

High-resolution ultrasound and magnetic resonance imaging of ulnar nerve neuropathy in the distal Guyon tunnel.

OBJECTIVE: The aim of the present study is to describe the ultrasound (US) and magnetic resonance imaging (MRI) findings in patients with neuropathies affecting the deep (DB) and superficial (SB) branches of the Ulnar nerve (UN) and to investigate the potential role of imaging modalities in the diagnostic workup of these conditions. MATERIALS AND METHODS: We screened our institutional imaging database to identify patients with a diagnosis of UN mononeuropathy, and among them, we reviewed the cases where US disclosed pathological findings affecting the UN terminal divisions. In this latter subgroup, we retrieved available data on MRI and electrodiagnostic tests performed by the patients during the diagnostic workup. All the patients were evaluated with US machines equipped with 17-5-MHz, 18-4-MHz, 24-8-MHz, or 22-8-MHz probes. MRI exams were performed on a 3-T unit equipped with a 64-channel head RF coil. RESULTS: Among 166 patients with UN mononeuropathy, we retrieved 15 patients (9%) for which US detected pathological findings affecting the UN terminal divisions, consisting of 7 cases of DB neuropathy, 4 cases of SB neuropathy, and 4 cases of combined neuropathy involving both nerves. Seven (46.7%) patients were submitted to MRI to integrate US findings. Among patients with SB and DB neuropathies, imaging allowed the identification of 7 traumatic nerve injuries, 2 nerve tumors, and 6 entrapment neuropathies, including 4 cases of nerve compression by a ganglion cyst. CONCLUSION: High-resolution US and MRI are accurate modalities for the investigation of patients with SB/DB neuropathy, can provide critical information on the cause of nerve damage, and guide therapeutic decisions. CRITICAL RELEVANCE STATEMENT: High-resolution US and MRI are accurate modalities for the investigation of patients with superficial/deep branch of the ulnar nerve neuropathy. In the proper setting, US may be regarded as a first-line approach in patients with suspected neuropathies affecting these small branches. KEY POINTS: • Neuropathies affecting the distal ulnar nerve often require multimodal investigations. • US and MRI can provide detailed morphological information about the terminal branches of the ulnar nerve. • US may be considered as a first-line approach in suspected distal ulnar nerve neuropathies.

Adhesive Capsulitis of the Shoulder: Current Concepts on the Diagnostic Work-Up and Evidence-Based Protocol for Radiological Evaluation.

Adhesive capsulitis is an idiopathic and disabling disorder characterized by intense shoulder pain and progressive limitation of active and passive glenohumeral joint range of motion. Although adhesive capsulitis has been traditionally considered a diagnosis of exclusion that can be established based on a suggestive medical history and the detection of supporting findings at the physical exam, imaging studies are commonly requested to confirm the diagnostic suspicion and to exclude other causes of shoulder pain. Indeed, clinical findings may be rather unspecific, and may overlap with diseases like calcific tendinitis, rotator cuff pathology, acromioclavicular or glenohumeral arthropathy, autoimmune disorders, and subacromial/subdeltoid bursitis. Magnetic resonance imaging, magnetic resonance arthrography, and high-resolution ultrasound have shown high sensitivity and accuracy in diagnosing adhesive capsulitis through the demonstration of specific pathological findings, including thickening of the joint capsule and of the coracohumeral ligament, fibrosis of the subcoracoid fat triangle, and extravasation of gadolinium outside the joint recesses. This narrative review provides an updated analysis of the current concepts on the role of imaging modalities in patients with adhesive capsulitis, with the final aim of proposing an evidence-based imaging protocol for the radiological evaluation of this condition.

Ultrasound of the palmar aspect of the hand: normal anatomy and clinical applications of intrinsic muscles imaging.

Intrinsic hand muscles play a fundamental role in tuning the fine motricity of the hand and may be affected by several pathologic conditions, including traumatic injuries, atrophic changes induced by denervation, and space-occupying masses. Modern hand surgery techniques allow to target several hand muscle pathologies and, as a direct consequence, requests for hand imaging now carry increasingly complex diagnostic questions. The progressive refinement of ultrasound technology and the current availability of high and ultra-high frequency linear transducers that allow the investigation of intrinsic hand muscles and tendons with incomparable resolution have made this modality an essential tool for the evaluation of pathological processes involving these tiny structures. Indeed, intrinsic hand muscles lie in a superficial position and are amenable to investigation by means of transducers with frequency bands superior to 20 MHz, offering clear advantages in terms of resolution and costs compared to magnetic resonance imaging. In addition, ultrasound allows to perform dynamic maneuvers that can critically enhance its diagnostic power, by examining the questioned structure during stress tests that simulate the conditions eliciting clinical symptoms. The present article aims to review the anatomy, the ultrasound scanning technique, and the clinical application of thenar, hypothenar, lumbricals and interossei muscles imaging, also showing some examples of pathology involving these structures.

Ultrasound of the plantar foot: a guide for the assessment of plantar intrinsic muscles.

Plantar intrinsic muscles play a pivotal role in posture control and gait dynamics. They help maintain the longitudinal and transverse arches of the foot, and they regulate the degree and velocity of arch deformation during walking or running. Consequently, pathologies affecting the plantar intrinsic muscles (for instance, acquired and inherited neuropathies) lead to foot deformity, gait disorders, and painful syndromes. Intrinsic muscle malfunctioning is also associated with multifactorial overuse or degenerative conditions such as pes planus, hallux valgus, and plantar fasciitis. As the clinical examination of each intrinsic muscle is challenging, ultrasound is gaining a growing interest as an imaging tool to investigate the trophism of these muscular structures and the pattern of their alterations, and potentially to follow up on the effects of dedicated rehabilitation protocols. The ten plantar intrinsic muscles can be dived into three groups (medial, central and lateral) and four layers. Here, we propose a regional and landmark-based approach to the complex sonoanatomy of the plantar intrinsic muscles in order to facilitate the correct identification of each muscle from the superficial to the deepest layer. We also summarize the pathological ultrasound findings that can be encountered when scanning the plantar muscles, pointing out the patterns of alterations specific to certain conditions, such as plantar nerves mononeuropathies.

High-resolution US of the facial vessels with new facial vein landmarks for reconstructive surgery and dermal injection.

BACKGROUND: Accurate knowledge of vessel anatomy is essential in facial reconstructive surgery. The technological advances of ultrasound (US) equipment with the introduction of new high-resolution probes improved the evaluation of facial anatomical structures. Our study had these objectives: the primary objective was to identify new surgical landmarks for the facial vein and to verify their precision with US, the secondary objective was to evaluate the potential of high-resolution US examination in the study of both the facial artery and vein. METHODS: Two radiologists examined a prospective series of adult volunteers with a 22-8 MHz hockey-stick probe. Two predictive lines of the facial artery and vein with respective measurement points were defined. The distance between the facial vein and its predictive line (named mandibular-orbital line) was determined at each measurement point. The distance from the skin and the area of the two vessels were assessed at every established measurement point. RESULTS: Forty-one volunteers were examined. The median distance of the facial vein from its predictive line did not exceed 2 mm. The facial vein was visible at every measurement point in all volunteers on the right side, and in 40 volunteers on the left. The facial artery was visible at every measurement point in all volunteers on the right and in 37 volunteers on the left. CONCLUSIONS: The facial vein demonstrated a constant course concerning the mandibular-orbital line, which seems a promising clinical and imaging-based method for its identification. High-resolution US is valuable in studying the facial artery and vein. RELEVANCE STATEMENT: High-resolution US is valuable for examining facial vessels and can be a useful tool for pre-operative assessment, especially when combined with the mandibular-orbital line, a new promising imaging and clinical technique to identify the facial vein. KEY POINTS: • High-resolution US is valuable in studying the facial artery and vein. • The facial vein demonstrated a constant course concerning its predictive mandibular-orbital line. • The clinical application of the mandibular-orbital line could help reduce facial surgical and cosmetic procedure complications.

Recurrent motor branch neuropathy in carpal tunnel syndrome: An ultrasound study.

INTRODUCTION/AIMS: The reason for the variable rate of progression of patients with carpal tunnel syndrome (CTS) to thenar muscles impairment is not fully understood. The aim of this study was to evaluate the occurrence of ultrasound signs of recurrent motor branch (RMB) neuropathy in patients with CTS and to correlate imaging findings with clinical and electrophysiological data. METHODS: Two cohorts were recruited, one consisting of CTS patients with electrodiagnostic evidence of prolonged median distal motor latency from wrist to thenar eminence and another consisting of sex- and age-matched healthy controls. Ultrasound reliability of RMB measurement was assessed by the calculation of the interclass correlation coefficient (ICC). Patients were evaluated with electrodiagnostic tests and asked to complete the Boston Carpal Tunnel Questionnaire. The difference between the RMB diameter in patients and controls was analyzed using a t test. Correlations between RMB diameter and other parameters were assessed using linear mixed models. RESULTS: 46 hands from 32 patients with CTS and 50 hands from 50 controls were evaluated. The intra- and interobserver agreements in RMB measurement were very good (ICC = 0.84; 95% confidence interval [CI], 0.75 to 0.90) and good (ICC = 0.79; 95% CI, 0.69 to 0.87). The RMB diameter was significantly larger in patients than in controls (P < .0001). No significant correlation was found between the RMB diameter and other variables, except for BMI and median nerve cross-sectional area. DISCUSSION: Ultrasound is reliable in identifying the RMB and characterizing its abnormalities. In this patient cohort, ultrasound allowed for detection of definite signs of RMB compression neuropathy.

Imaging of Anatomical Variants Around the Wrist and Hand.

Wrist and hand anatomy may present several clinically relevant variants that involve bones, muscles, tendons, and nerves. Thorough knowledge of these abnormalities and their appearance in imaging studies is useful for proper management. In particular, it is necessary to differentiate the incidental findings that do not represent a trigger for a specific syndrome from those anomalies causing symptoms and functional impairment. This review reports the most common anatomical variants encountered in clinical practice and briefly discusses their embryogenesis, related clinical syndrome if present, and their appearance using different imaging techniques. The information each diagnostic study (ultrasonography, radiographs, computed tomography, and magnetic resonance imaging) may provide is described for each condition.

High-pressure injection injury of the hand: Clinical usefulness of ultrasound as an early diagnostic tool.

High-pressure injection injuries of the hand are uncommon accidents with potentially catastrophic complications. We present a case of a 49-years-old male with a high-pressure injection of motor oil in his left hand. Ultrasound accurately demonstrated soft tissue infiltration and late complications, playing a fundamental role in the treatment choice.

Immune checkpoint inhibitor-related pneumonitis and COVID-19: a case-matched comparison of CT findings.

OBJECTIVES: To compare the radiological findings of immune checkpoint inhibitor-related pneumonitis (IRP) and COVID-19 pneumonia, evaluating the potential of the CO-RADS score to differentiate between them. METHODS: Two readers blindly reviewed chest CTs from age- and sex-matched groups of 33 patients with IRP and 33 patients with COVID-19 pneumonia. Each examiner evaluated the presence of 13 CT features, semiquantitatively scored lung involvement, and assigned a CO-RADS score. Inter-reader reliability in the assessment of CT features and CO-RADS categories was evaluated with Cohen's κ. Distribution differences between groups were evaluated with the χ2, Fisher's, and Mann-Whitney U tests. RESULTS: Substantial or higher inter-reader reliability was found in CO-RADS assignments (κ = 0.664) and in the evaluation of CT features (κ ≥ 0.638), among which the sole feature found to significantly differentiate IRP from COVID-19 pneumonia was unilateral presentation (p < 0.001). Lung involvement semiquantitative scores and CO-RADS scores were significantly higher (p < 0.001) in COVID patients (median involvement score 4, IQR 4-6; median CO-RADS score 5, IQR 4-5) than in IRP patients (median involvement score 2.5, IQR 2-4; median CO-RADS score 3, IQR 3-4) but exploratory analysis of CO-RADS specificity revealed comparatively low values, ranging between 51.5% (Reader 1) and 54.6% (Reader 2). CONCLUSIONS: CT features of IRP and COVID-19 pneumonia frequently overlap, save for the extent of lung involvement and bilaterality. In the current SARS-CoV-2 pandemic, the low specificity of the CO-RADS score for the differential diagnosis of COVID-19 pneumonia and IRP may prompt to reconsider the role of imaging in IRP work-up.

Ultrasound assessment of degenerative muscle sarcopenia: the University of Barcelona ultrasound scoring system for sarcopenia.

AIM: This study aimed to (1) determine the intraobserver and interobserver reliability of ultrasonographic measurement of muscle thickness (MT) and cross-sectional area (CSA) of the rectus femoris and biceps brachii, correlating these values with manual measurements on dissected cadavers and (2) develop the first semiquantitative musculoskeletal ultrasound (MSUS) scoring system of muscle morphology in sarcopenia and assess its intraobserver and interobserver reliability. In addition, the MSUS morphology score was compared with the corresponding histological images to verify concurrent validity. METHODS: Ten cryopreserved limbs of 10 cadavers aged 68-91 years were evaluated. The MSUS scoring system was based on the severity of muscle degeneration on a 3-point qualitative scale: grade 1 (normal), grade 2 (moderate changes) and grade 3 (severe changes). Reliability was assessed with intraclass correlation coefficient (ICC) for the MT and CSA and with Cohen's kappa coefficients (κ) for the MSUS scoring system. Concurrent validity was analysed with ICC. RESULTS: The results showed excellent intraobserver and interobserver reliability for both the MSUS evaluation of MT and CSA (ICC ≥0.93). The MSUS scoring system showed excellent intraobserver reliability (κ=1.0) and very good interobserver reliability (κ=0.85). There was also a high intra- and inter-observer reliability for the histological scorings (ĸ ≥0.85 and mean ĸ=0.70, respectively), as well as high reliability between the histology and MSUS scoring systems (ICC=0.92). All results were statistically significant (p≤0.001). CONCLUSION: MSUS measures of MT and CSA and the novel MSUS scoring system for degenerative muscle changes in sarcopenia was found to be reliable and strongly associated with histological findings.

High-Resolution Ultrasound of Facial Muscles: Sonoanatomy, Scanning Technique, and Pathological Cases.

The aim of the present work is to review the sonographic appearance of facial muscles with high-frequency transducers and to illustrate a step-by-step scanning technique that enables an effective evaluation of them. In addition, we highlighted the clinical application showing some pathological cases demonstrated with ultrasound (US). The recent technological advances have greatly enlarged the potential of high-resolution US in the evaluation of the face. Furthermore, the clinical indications of this technique are expected to increase in the near future.

High-resolution ultrasound of peripheral neuropathies in rheumatological patients: An overview of clinical applications and imaging findings.

Peripheral neuropathies are surprisingly common and can be associated with a number of conditions, including rheumatological diseases. Whether the co-existence of peripheral neuropathies with rheumatological disorders is coincidental or related to a common pathogenic mechanism, these disabling conditions can affect the outcome of rheumatological patients and should be targeted with specific treatment. The clinical presentation of peripheral neuropathy can be multifaceted and difficult to recognize in polysymptomatic patients. However, physicians adopting state-of-art diagnostic strategies, including nerve imaging, may improve the detection rate and management of neuropathies. In particular, a diagnostic approach relying exclusively on clinical history and nerve conduction studies may not be sufficient to disclose the etiology of the nerve damage and its anatomical location and thus requires integration with morphological studies. High-Resolution Ultrasound (HRUS) is increasingly adopted to support the diagnosis and follow-up of both joint disorders in rheumatology and peripheral neuropathies of different etiologies. In this review, the different types of nerve disorders associated with the most common syndromes of rheumatological interest are discussed, focusing on the distinctive sonographic features.

MND Phenotypes Differentiation: The Role of Multimodal Characterization at the Time of Diagnosis.

Pure/predominant upper motor neuron (pUMN) and lower motor neuron (pLMN) diseases have significantly better prognosis compared to amyotrophic lateral sclerosis (ALS), but their early differentiation is often challenging. We therefore tested whether a multimodal characterization approach embedding clinical, cognitive/behavioral, genetic, and neurophysiological data may improve the differentiation of pUMN and pLMN from ALS already by the time of diagnosis. Dunn's and chi-squared tests were used to compare data from 41 ALS, 34 pLMN, and 19 pUMN cases with diagnoses confirmed throughout a 2-year observation period. Area under the curve (AUC) analyses were implemented to identify the finest tools for phenotypes discrimination. Relative to ALS, pLMN showed greater lower limbs weakness, lower UMN burden, and progression rate (p < 0.001−0.04). PUMN showed a greater frequency of lower limbs onset, higher UMN burden, lower ALSFRS-r and MRC progression rates (p < 0.001−0.03), and greater ulnar compound muscle action potential (CMAP) amplitude and tibial central motor conduction time (CMCT) (p = 0.05−0.03). The UMN progression rate was the finest measure to identify pLMN cases (AUC = 90%), while the MRC progression rate was the finest tool to identify pUMN (AUC = 82%). Detailed clinical and neurophysiological examinations may significantly improve MNDs differentiation, facilitating prognosis estimation and ameliorating stratification strategies for clinical trials enrollment.

High-resolution Doppler ultrasound in systemic sclerosis: Analysis of digital arteries and nailfold microvasculature using 18-5 MHz and 33-9 MHz probes.

INTRODUCTION: Newly developed Doppler techniques enable the sampling of slow vascular flows and the extrapolation of spectral parameters in distal arterioles. The aim of this study was to investigate the role of spectral analysis performed by means of ultra-high frequency ultrasound (US) in the evaluation of the peripheral vascular bed of systemic sclerosis (SSc) patients. METHODS: Both hands of 33 patients affected by diffuse cutaneous SSc and 34 volunteers were evaluated with a US machine equipped with 33-9 MHz and 18-5 MHz transducers. Proximal resistive index and the peak systolic velocity (pRI and pPSV, respectively), were calculated at the level of the second interdigital artery. The distal resistive index (dRI) was calculated at the level of a nailfold arteriole of the third finger. All SSc patients had been previously divided into 4 subgroups according to their nailfold videocapillaroscopic (NVC) patterns following accepted criteria. RESULTS: SSc patients showed a significantly slower systolic velocity at the level of the second interdigital artery (pPSV [SD] = 8.38 [3] cm/s vs pPSV [SD] = 11.14 [4.5] cm/s; P = .005) and a higher dRI (dRI [SD] = 0.65 (0.14) vs dRI [SD] = 0.57 [0.11); P = .0115). No differences were found between the pRI values measured in the SSc patients and those of the controls (pRI [SD] = 0.76 [0.11] vs pRI [SD] = 0.73 [0.12]; P = .359]. The subgroup analysis did not show any significant difference when pPSV, pRI and dRI were compared among NVC morphological patterns. CONCLUSION: High-resolution Doppler analysis of digital distal arterioles may disclose subtle abnormalities in the downstream microvasculature of SSc patients that could be missed when the examination is performed at a more proximal level and/or using lower Doppler frequencies.

Neurological long-COVID in the outpatient clinic: Two subtypes, two courses.

INTRODUCTION: Symptoms referable to central and peripheral nervous system involvement are often evident both during the acute phase of COVID-19 infection and during long-COVID. In this study, we evaluated a population of patients with prior COVID-19 infection who showed signs and symptoms consistent with neurological long-COVID. METHODS: We prospectively collected demographic and acute phase course data from patients with prior COVID-19 infection who showed symptoms related to neurological involvement in the long-COVID phase. Firstly, we performed a multivariate logistic linear regression analysis to investigate the impact of demographic and clinical data, the severity of the acute COVID-19 infection and hospitalization course, on the post-COVID neurological symptoms at three months follow-up. Secondly, we performed an unsupervised clustering analysis to investigate whether there was evidence of different subtypes of neurological long COVID-19. RESULTS: One hundred and nine patients referred to the neurological post-COVID outpatient clinic. Clustering analysis on the most common neurological symptoms returned two well-separated and well-balanced clusters: long-COVID type 1 contains the subjects with memory disturbances, psychological impairment, headache, anosmia and ageusia, while long-COVID type 2 contains all the subjects with reported symptoms related to PNS involvement. The analysis of potential risk-factors among the demographic, clinical presentation, COVID 19 severity and hospitalization course variables showed that the number of comorbidities at onset, the BMI, the number of COVID-19 symptoms, the number of non-neurological complications and a more severe course of the acute infection were all, on average, higher for the cluster of subjects with reported symptoms related to PNS involvement. CONCLUSION: We analyzed the characteristics of neurological long-COVID and presented a method to identify well-defined patient groups with distinct symptoms and risk factors. The proposed method could potentially enable treatment deployment by identifying the optimal interventions and services for well-defined patient groups, so alleviating long-COVID and easing recovery.

The EFSUMB Guidelines and Recommendations for Musculoskeletal Ultrasound - Part II: Joint Pathologies, Pediatric Applications, and Guided Procedures.

The second part of the Guidelines and Recommendations for Musculoskeletal Ultrasound (MSUS), produced under the auspices of EFSUMB, following the same methodology as for Part 1, provides information and recommendations on the use of this imaging modality for joint pathology, pediatric applications, and musculoskeletal ultrasound-guided procedures. Clinical application, practical points, limitations, and artifacts are described and discussed for every joint or procedure. The document is intended to guide clinical users in their daily practice.

Clinical indications for image-guided interventional procedures in the musculoskeletal system: a Delphi-based consensus paper from the European Society of Musculoskeletal Radiology (ESSR)-part VII, nerves of the lower limb.

OBJECTIVES: To perform a Delphi-based consensus on published evidence on image-guided interventional procedures for peripheral nerves of the lower limb (excluding Morton's neuroma) and provide clinical indications. METHODS: We report the results of a Delphi-based consensus of 53 experts from the European Society of Musculoskeletal Radiology who reviewed the published literature for evidence on image-guided interventional procedures offered around peripheral nerves in the lower limb (excluding Morton's neuroma) to derive their clinical indications. Experts drafted a list of statements and graded them according to the Oxford Centre for evidence-based medicine levels of evidence. Consensus was considered strong when > 95% of experts agreed with the statement or broad when > 80% but < 95% agreed. The results of the Delphi-based consensus were used to write the paper. RESULTS: Nine statements on image-guided interventional procedures for peripheral nerves of the lower limb have been drafted. All of them received strong consensus. Image-guided pudendal nerve block is safe, effective, and well tolerated with few complications. US-guided perisciatic injection of anesthetic provides good symptom relief in patients with piriformis syndrome; however, the addition of corticosteroids to local anesthetics still has an unclear role. US-guided lateral femoral cutaneous nerve block can be used to provide effective post-operative regional analgesia. CONCLUSION: Despite the promising results reported by published papers on image-guided interventional procedures for peripheral nerves of the lower limb, there is still a lack of evidence on the efficacy of most procedures. KEY POINTS: • Image-guided pudendal nerve block is safe, effective, and well tolerated with few complications. • US-guided perisciatic injection of anesthetic provides good symptom relief in patients with piriformis syndrome; however, the addition of corticosteroids to local anesthetics still has an unclear role. • US-guided lateral femoral cutaneous nerve block can be used to provide effective post-operative regional analgesia. The volume of local anesthetic affects the size of the blocked sensory area.

Imaging Characteristics of the Proximal Lateral Collateral Ligament of the Knee: Findings on Ultrasound and MRI With Histologic Correlation.

OBJECTIVES: Determine prevalence of increased signal intensity of the lateral collateral ligament (LCL) of the knee on MRI and decreased echogenicity on ultrasound, and compare with cadaveric histologic evaluation. METHODS: After IRB approval of this prospective study with informed consent, patients having knee MRI were additionally evaluated with ultrasound. Signal intensities of LCL on MRI (low, intermediate, high), echogenicity at ultrasound (hyperechoic, hypoechoic, anechoic), and extent of findings were assessed. Descriptive statistics, Wilcoxon signed ranked test, and intraclass correlation coefficient (ICC) were calculated. Two cadaveric knees were imaged with MRI and ultrasound, including histologic LCL evaluation. RESULTS: Seventy-three subjects were included (39 males, 34 females; mean age 48 ± 14 years) with 77 knee examinations. On MRI, low, intermediate, and high signals were present in 21% (16/77), 75% (58/77), and 4% (3/77), respectively. On ultrasound, echogenicity was assessed as hyperechoic, hypoechoic, and anechoic in 62% (48/77), 38% (29/77), and 0% (0/77), respectively. Mean length of increased signal was 8.6 mm (±4.9) on MRI, and 6.5 mm (±4.8) on ultrasound. The ICC showed a good to excellent intermodality reliability (0.735-0.899) without statistically significant difference for interreader measurements (P = .163-.795). Histology evaluation showed transition of ligament fibers to fibrocartilage at its insertion with increased connective tissue mucin corresponding to MRI and ultrasound findings. CONCLUSIONS: Increased signal intensity of the proximal LCL on ultrasound and MRI is common and corresponds to normal connective tissue mucin.