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 ultrasound of spigelian and groin hernias: a closer look at fascial architecture and aponeurotic passageways.

From the clinical point of view, a proper diagnosis of spigelian, inguinal and femoral hernias may be relevant for orienting the patient's management, as these conditions carry a different risk of complications and require specific approaches and treatments. Imaging may play a significant role in the diagnostic work-up of patients with suspected abdominal hernias, as the identification and categorization of these conditions is often unfeasible on clinical ground. Ultrasound imaging is particularly suited for this purpose, owing to its dynamic capabilities, high accuracy, low cost and wide availability. The main limitation of this technique consists of its intrinsic operator dependency, which tends to be higher in difficult-to-scan areas such as the groin because of its intrinsic anatomic complexity. An in-depth knowledge of the anatomy of the lower abdominal wall is, therefore, an essential prerequisite to perform a targeted ultrasound examination and discriminate among different types of regional hernias. The aim of this review is to provide a detailed analysis of the fascial architecture and aponeurotic passageways of the abdominal wall through which spigelian, inguinal and femoral hernias extrude, by means of schematic drawings, ultrasound images and video clips. A reasoned landmark-based ultrasound scanning technique is described to allow a prompt and reliable identification of these pathologic conditions.

High-resolution ultrasound of the marginal mandibular branch of the facial nerve: Normal appearance and pathological findings in a postsurgical case series.

BACKGROUND: The aim of this study was to validate high-resolution ultrasound (US) as an imaging modality able to map the normal marginal mandibular nerve (MMN) and recognize its abnormalities in the postoperative setting. METHODS: The ability of US to recognize the MMN was first tested by injecting latex under US guidance on three fresh frozen cadavers. Then, a standardized scanning protocol was established on 20 healthy volunteers based on appropriate landmarks. Finally, a postsurgical series of three patients with MMN abnormalities were examined with US. RESULTS: In the cadaveric study, US-guided latex injection provided identification of the MMN. In healthy volunteers, US was able to recognize the MMN for a segment of 3.4 ± 1.2 cm in length. Pathologic abnormalities of the MMN were detected and characterized in three patients. CONCLUSIONS: High-resolution US is a valuable diagnostic tool to identify the MMN and might have potential for detecting its pathologic changes.

High-Resolution Ultrasound of Small Clinically Relevant Nerves Running Across the Posterior Triangle of the Neck.

With the advent of high-frequency ultrasound (US) transducers, new perspectives have been opened in evaluating millimetric and submillimetric nerves that, despite their dimensions, can be considered relevant in clinical practice. In the posterior triangle of the neck, the suprascapular, long thoracic, phrenic, supraclavicular, great auricular, lesser occipital, and transverse cervical nerves are amenable to US examination and the object of special interest because they may be involved in many pathologic processes or have a value as targets of advanced therapeutic procedures. The correct identification of these nerves requires a deep knowledge of local neck anatomy and the use of a complex landmarks-based approach with US. This article describes the anatomy and US technique to examine small but clinically relevant nerves of the posterior triangle of the neck (excluding the brachial plexus), reviewing the main pathologic conditions in which they may be involved.

Ultrasound Imaging Guide for Assessment of the Intrinsic Ligaments Stabilizing the Subtalar and Midtarsal Joints.

Ligament injuries around the subtalar, talocalcaneonavicular, and calcaneocuboid joints are often underestimated on clinical and imaging findings during investigation of patients with ankle and foot injuries. Because a delayed diagnosis of midtarsal ligament tears may lead to chronic pain and functional disability, an in-depth knowledge of the complex regional anatomy and of the appropriate ultrasound scanning technique is a prerequisite for evaluating these structures and avoiding misdiagnoses. The objective of this article is twofold: to describe the relevant anatomy and biomechanics related to the ligaments that stabilize the subtalar, talocalcaneonavicular, and calcaneocuboid joints, and to illustrate reasoned landmark-based scanning techniques to provide a systematic examination of these ligaments and thus make ultrasound an effective tool for assessment of patients with suspected subtalar or midtarsal sprain.

Anatomical study of the iliohypogastric, ilioinguinal, and genitofemoral nerves using high-resolution ultrasound.

INTRODUCTION: In this study we aimed to determine whether high-resolution ultrasound (US) can identify the iliohypogastric (IH), ilioinguinal (II), and genitofemoral (GF) nerves and their relations. METHODS: This investigation, initially undertaken in cadavers, was followed by a high-resolution US study in 30 healthy adult volunteers (180 nerves) by 2 musculoskeletal radiologists on separate occasions, using 2 different approaches (proximal to distal and distal to proximal). A 0-3 scale was used to assess nerve visibility. Location and course of the IH, II, and GF nerves and their relations to adjacent anatomical structures were analyzed. RESULTS: Nerves and their terminal branches were better visualized with the distal-to-proximal approach (P < 0.05). Visualization of the terminal branches was possible in up to 60% of volunteers. CONCLUSIONS: High-resolution ultrasound (US) can identify the IH, II, and GF nerves at the level of the abdominal wall and the terminal branches in the majority of volunteers.

Imaging finger joint instability with ultrasound.

Closed injuries affecting the metacarpophalangeal and interphalangeal joints and their stabilizers in the thumb and fingers occur very commonly in athletes, possibly leading to finger joint instability and long-standing or permanent disability. This article reviews the spectrum of joint injuries of the thumb and fingers that are common in the athletic population with a main focus on the ultrasound features of collateral ligament tears, palmar plate injuries, and thumb sesamoid fractures. A thorough understanding of the complex anatomy, mechanism of injury, soft tissue abnormalities, and imaging findings is critical in the diagnostic work-up of closed finger joint trauma and may help improve outcomes.

High-Resolution ultrasound of the pudendal nerve: normal anatomy.

INTRODUCTION: In this study we aimed to determine whether high-resolution ultrasound (US) can identify the pudendal nerve and its terminal branches. We also attempted to identify the best approach for visualizing these structures. METHODS: Normal anatomy of the pudendal nerve was evaluated in 3 cadavers and 20 healthy volunteers proximally at the level of the ischial spine and distally with low-frequency (2-5-MHZ) and high-frequency (12-7-MHZ and 17-5-MHZ) transducers. Two musculoskeletal radiologists performed the examinations and evaluations. Volunteers were placed in 3 different positions, which allowed different approaches (posterior, medial, and anterior transperineal). A 0-3 scale was used to assess nerve visibility. RESULTS: Visualization of the pudendal nerve at the ischial spine was best when using a medial approach (P < 0.004); the terminal branches were seen best with the anterior approach (P < 0.002). CONCLUSION: High-resolution ultrasound (US) can identify the pudendal nerve and its terminal branches.

Increased reflectivity and loss in bulk of the pronator quadratus muscle does not always indicate anterior interosseous neuropathy on ultrasound.

PURPOSE: To assess if isolated atrophy of the pronator quadratus muscle indicates anterior interosseous neuropathy on ultrasound. MATERIALS AND METHODS: IRB approval and written informed from every patient were obtained. A prospective study including 100 consecutive wrist and hand ultrasound studies in 77 patients (46 females and 31 males; 23 patients had bilateral studies) with a mean age of 45 years (range, 21-86 years) was performed between March 2010 and January 2012. The patients were chosen irrespective of age, sex, and body mass index. The studies were performed for several reasons, the most common being wrist pain (n=56), followed by ganglion cyst (n=11) and soft-tissue masses (n=10). Clinical histories, previous imaging studies and US examinations were evaluated to rule out anterior interosseous nerve neuropathy. US examinations were performed with a commercially available equipment. Pronator quadratus was checked for atrophy using flexor pollicis longus, flexor digitorum superficialis and profundus for comparison. Descriptive statistic was used. RESULTS: US signs of pronator quadratus atrophy were present in 7/100 (7%) of patients. None of the patients had a bilateral atrophy of the pronator quadratus. In the patients with atrophy of the pronator quadratus, adjacent flexor muscles were normal. There was no significant difference between males and females (3 females vs 4 males) (p=0.506). CONCLUSION: Increased reflectivity and loss in bulk of the pronator quadratus muscle does not always indicate anterior interosseous neuropathy on ultrasound.

Nerves of the hand beyond the carpal tunnel.

Imaging studies including ultrasound (US) and magnetic resonance imaging may be required to evaluate the median nerve in patients with suspected carpal tunnel syndrome. However, the radial and ulnar nerves contribute to sensory and motor innervations to the hand as well. Compressive, traumatic, and iatrogenic events may damage the small terminal branches of these nerves. In the hand, US is able to identify injuries of the median, ulnar, radial nerve, and terminal branches. This article presents the role of imaging to evaluate the nerves of the hand with an emphasis on US. Due to its high-resolution capabilities, US is useful to determine the location, extent, and type of nerve lesion. Moreover, US is useful for a postsurgical assessment. The anterior interosseous nerve, Guyon's tunnel syndrome, and Wartenberg's syndrome are also described.

Ultrasound demonstration of distal triceps tendon tears.

PURPOSE: Rupture of the distal triceps tendon is an uncommon injury that may be unrecognized on clinical examination. The purpose of the study is to describe the role of US in distal triceps tendon tears evaluation. MATERIALS AND METHODS: IRB approval was obtained and patients gave written informed consent. Of 77 consecutive US examinations of the elbow obtained over a five-year period, eight patients with correlative MR and surgery available were identified having partial or complete distal triceps tendon tear. RESULTS: N = 4 complete tears of the triceps tendon and n = 4 partial tears of the distal triceps involving the lateral/superficial head were identified. Patients with partial tear had a history of a single traumatic event that determined a sudden eccentric contraction of the triceps muscle against resistance. US demonstrated on axial and longitudinal planes a partial tear of the triceps brachii tendon that resulted in a fusiform swelling and retraction of the lateral/superficial head in four patients. It was possible to identify the normal insertion of the medial head of the triceps moving the transducer medially. MR and surgical findings were concordant with US findings in every patient. CONCLUSION: Ultrasound is able to differentiate complete from partial triceps tendon tears. US has the potential to identify isolated lesions of the lateral/superficial head of the triceps with an intact medial head.

Brachial plexus and nerves about the shoulder.

Ultrasound (US) and MR imaging have been shown able to detect in-depth features of brachial plexus anatomy and to localize pathological lesions in disorders where electrophysiology and physical findings are nonspecific or nonlocalizing. High-end gradient technology, phased array coils, and selection of an appropriate protocol of pulse sequences are the main requirements to evaluate the brachial plexus nerves with MR imaging and to distinguish between intrinsic and extrinsic pathological changes. A careful scanning technique based on anatomical landmarks is required to image the brachial plexus nerves with US. In traumatic injuries, MR imaging and myelographic techniques can exclude nerve lesions at the level of neural foramina and at intradural location. Outside the spinal canal, US is an excellent alternative to MR imaging to determine the presence of a lesion, to establish the site and the level of nerve involvement, as well as to confirm or exclude major nerve injuries. In addition to brachial plexus injuries, MR imaging and US can be contributory in a variety of nontraumatic brachial plexopathies of a compressive, neoplastic, and inflammatory nature. In the thoracic outlet syndrome, imaging performed in association with postural maneuvers can help diagnose dynamic compressions. MR imaging and US are also effective to recognize neuropathies about the shoulder girdle involving the suprascapular, axillary, long thoracic, and spinal accessory nerves that may mimic brachial plexopathy. In this article, the clinical entities just listed are discussed independently, providing an overview of the current status of knowledge regarding imaging assessment.

Imaging of neuropathies about the ankle and foot.

Neuropathies about the ankle and foot may be the cause of chronic pain and disability. In most cases, these conditions derive from mechanical or dynamic compression of a segment of a nerve within a narrow osteofibrous tunnel, an opening in a fibrous structure, or a passageway close to a ligament or a muscle. Although the evaluation of nerve disorders primarily relies on neurological examination and electrophysiology, diagnostic imaging is currently used as a complement to help define the site and etiology of nerve compression and exclude other disease possibly underlying the patient' symptoms. In this article, a review of the anatomical and pathological features of nerve entrapments in the distal lower extremity is presented on ultrasound and magnetic resonance imaging, according to the nerve involved.

Muscle variants of the upper and lower limb (with anatomical correlation).

Several accessory muscles in the upper and lower limb have been described in the medical literature. Most are asymptomatic and represent incidental findings at imaging. In some instances, however, these muscles may become clinically relevant producing palpable swelling, entrapment of neurovascular structures, or exercise-related pain. The diagnosis of accessory muscles is based on recognition of their typical location and on cross-sectional imaging features. Familiarity with their most common location and knowledge of the possible clinical syndromes caused by these supernumerary structures may aid in diagnosis and treatment.