Special anatomy series. Imaging inner ear structures with high-frequency ultrasound: Application to physical rehabilitation space medicine.

Objective: The objective of this paper is to document the feasibility of image acquisition, image optimization, and sonographic appearance of the exposed anatomic windows of cadaveric inner ear dissection for purposes of potential future clinical evaluation as part of the developing area of physical and rehabilitation space medicine. Methods: Cadaveric dissection of the inner ear was conducted with the goal of exposing areas relevant to vestibular balance. Middle and inner ear structures of 3 human cadavers were imaged with multiple broadband transducers, including emphasis with higher frequency transducers. Results: The images were best optimized with 17 MHz and 22 MHz small footprint transducers. High-frequency ultrasound (US) images of the semicircular canals, vestibular and facial nerves, and utricles with reflected otoliths (otoconia) were obtained and reported in this article. Detailed visualization of both the vestibular nerve and facial nerve was accomplished, including identification of fascicular architecture. In addition, US reflection from the otoliths contained within the utricle was identified with sufficient clarity to provide surface measurements. Bony acoustic landmarks of the middle ear bones were identified by scanning externally from the tympanic membrane, including the dynamic movement of the bones with manual manipulation. Conclusion: US visualization has the potential to be an effective imaging modality to monitor potential changes to the otolith's size throughout extended space flight. To our knowledge, no prior study has reported US images of human inner ear structures.

Alpha-2 macroglobulin for the treatment of neuroma pain in the stump of a below-knee amputee patient.

This case report describes the successful treatment of neuroma pain in the setting of below knee amputations using alpha-2-macroglobulin (A2M). A 34-year-old female patient presented with 9 months of stump pain despite conservative treatment. The exam revealed persistent pain through rest periods and weight-bearing status during therapy. Ultrasound showed neuroma formation with neovascularization. The patient underwent two A2M hydrodissection treatments, 2 weeks apart. The patient reported significant pain relief. Ultrasound showed decreases in neovascularization and cross-sectional area of the neuroma. The patient was able to ambulate pain-free for 2 years and reported no pain since. A2M may be a treatment for patients with neuroma pain in the setting of amputations.

A standardized ultrasound approach in neuralgic amyotrophy.

Neuralgic amyotrophy (NA), also referred to as idiopathic brachial plexitis and Parsonage-Turner syndrome, is a peripheral nerve disorder characterized by acute severe shoulder pain followed by progressive upper limb weakness and muscle atrophy. While NA is incompletely understood and often difficult to diagnose, early recognition may prevent unnecessary tests and interventions and, in some situations, allow for prompt treatment, which can potentially minimize adverse long-term sequalae. High-resolution ultrasound (HRUS) has become a valuable tool in the diagnosis and evaluation of NA. Pathologic HRUS findings can be grouped into four categories: nerve swelling, swelling with incomplete constriction, swelling with complete constriction, and fascicular entwinement, which may represent a continuum of pathologic processes. Certain ultrasound findings may help predict the likelihood of spontaneous recovery with conservative management versus the need for surgical intervention. We recommend relying heavily on history and physical examination to determine which nerves are clinically affected and should therefore be assessed by HRUS. The nerves most frequently affected by NA are the suprascapular, long thoracic, median and anterior interosseous nerve (AIN) branch, radial and posterior interosseous nerve (PIN) branch, axillary, spinal accessory, and musculocutaneous. When distal upper limb nerves are affected (AIN, PIN, superficial radial nerve), the lesion is almost always located in their respective fascicles within the parent nerve, proximal to its branching point. The purpose of this review is to describe a reproducible, standardized, ultrasonographic approach for evaluating suspected NA, and to share reliable techniques and clinical considerations when imaging commonly affected nerves.

The value of high-resolution imaging in an occult peroneal intraneural ganglion cyst: illustrative case.

BACKGROUND: Foot drop is a common complaint with a broad differential diagnosis making imaging a key part of the diagnostic workup. The authors present a patient with an occult peroneal intraneural ganglion cyst who underwent imaging with high-frequency ultrasound (US) and high-resolution magnetic resonance imaging (MRI) to highlight the role of such techniques in cases of peroneal neuropathy. OBSERVATIONS: Intraneural ganglion cysts are emerging as a common cause of common peroneal neuropathy. Imaging with US and MRI is a valuable tool used to illustrate the pertinent anatomy and identify the articular branch joint connection and cyst as part of the surgical planning and definitive management. LESSONS: Intraneural ganglion cysts can be small or nearly invisible and failure to appreciate the intraneural cyst can lead to symptom or cyst persistence or recurrence. High-resolution modalities can be useful in the diagnosis and surgical planning of difficult cases.

Preoperative Imaging of Intraneural Ganglion Cysts: A Critical Systematic Analysis of the World Literature.

BACKGROUND: Advancements in imaging and an understanding of the pathomechanism for intraneural ganglion cyst formation have led to increased awareness and recognition of this lesion. However, the precise role of imaging has been advocated for but not formally evaluated. METHODS: We performed a systematic review of the world literature to study the frequency of imaging used to diagnose intraneural ganglion cysts at different sites and compared trends in identifying joint connections. RESULTS: We identified 941 cases of intraneural ganglion cysts, of which 673 had published imaging. Magnetic resonance imaging (MRI, n = 527) and ultrasonography (US, n = 123) were the most commonly reported. They occurred most frequently in the common peroneal nerve (n = 570), followed by the ulnar nerve at the elbow (n = 88), and the tibial nerve at the ankle (n = 58). A joint connection was identified in 375 cases (48%), with 62% of MRIs showing a joint connection, followed by 16% on US, and 6% on computed tomography (CT). MRI was statistically more likely to identify a joint connection than was US (P < 0.01). In the last decade, joint connections have been identified with increasing frequency using preoperative imaging, with up to 75% of cases reporting joint connections. CONCLUSIONS: Preoperative imaging plays an important role in establishing the diagnosis of intraneural ganglion cyst as well as treatment planning. Imaging has proved superior to the sole reliance of operative exposure to identify a joint connection, which is necessary to treat the underlying disease. Failure to identify cyst connections on imaging can result in an inability to truly address the underlying pathoanatomy at the time of definitive surgery, leading to a risk for clinical recurrence. Therefore, management should be guided by an intersection between new knowledge presented in the literature, clinical expertise, and surgeon experience.

Diagnostic and therapeutic musculoskeletal ultrasound applications of the shoulder.

High frequency ultrasound is a valuable tool for assessing soft tissue injuries about the shoulder. It has advantages over other imaging modalities including relatively low cost, portability, and dynamic real-time visualization. It has a high sensitivity for identifying tendon degeneration, bursitis, and rotator cuff tears. Ultrasound is also an excellent modality for diagnostic and therapeutic needle-guided procedures. A detailed knowledge of shoulder anatomy and transducer positioning is required for obtaining adequate diagnostic value from ultrasound. This Monograph is designed to help develop scanning protocols for optimizing image acquisition for musculoskeletal assessment of the shoulder. Muscle Nerve, 2019.

Ultrasound Visualization of Torsional Anatomic Changes From External Rotation of the Anterior Shoulder.

The sonographic appearance of soft tissue can be altered with movement. This can be related to both position change as well as torsional stress. The objective of this article is to demonstrate sonographic anatomy of the anterior shoulder as it moves into full external rotation. METHODS: Ultrasound images were obtained in a healthy human subject. Conventional imaging locations were selected that are typically utilized to assess musculoskeletal and peripheral nerve anatomy as well as perform therapeutic injections. The transducer was centered over each region to obtain both short- and long-axis views. A pair of sonographic images was recorded for both imaging planes at each site: the first in anatomic neutral and second in full external rotation. In addition, a video recording was made at each site to track the movement of the muscles and nerves during external rotation. RESULTS: The rotator interval including the intertubercular groove and biceps brachii long head moves far laterally when viewed in short axis, and it becomes out of plane when viewed in long axis. The subscapularis is relatively poorly visualized with the shoulder in neutral position, but the tendon and more distal aspect of the muscle are well visualized in full external rotation. The pectoralis major tendon insertion is well visualized in long axis with the shoulder in both neutral position and full external rotation. Movement of the humerus and the pectoralis major insertion are seen with shoulder rotation. The muscle appears to tighten and lengthen. The pectoralis major muscle is also seen in greater detail in external rotation. The cord level of the brachial plexus is also visualized at the infraclavicular portion of the anterior shoulder. The medial, posterior, and lateral cords are visualized in relation to the axillary artery. The relative position of the cords is only minimally altered with external rotation; however, the overlying pectoralis minor is tightened, and its influence can be visualized. DISCUSSION: External rotation has a considerable effect on the sonographic appearance of the anterior shoulder. Targets used for therapeutic injections, such as the bicipital groove, rotate out of clear view. Some chemodenervation targets, such as the muscle of the subscapularis, can only be accessed with the shoulder in full external rotation. Full external rotation of the shoulder also places torsional stress on some of the anterior shoulder structures, such as the pectorals, which can provide diagnostic clues in certain pathologic conditions. CONCLUSION: Movement into external rotation changes the sonographic appearance of the anatomic relationships of the anterior shoulder. Knowledge of these torsional changes can have both diagnostic and therapeutic implications.

Neuromuscular ultrasound of the brachial plexus: A standardized approach.

Reliable assessment of brachial plexus disorders can be challenging due to the complexity of the anatomy and variation of potential pathology. Electrodiagnostic testing can be both uncomfortable for the patient and inconclusive. Ultrasound can serve as a complement to clinical assessment, electrodiagnostic testing, and other imaging modalities. This study describes a systematic approach for performing neuromuscular ultrasound for suspected pathology in the brachial plexus. The literature regarding techniques for brachial plexus ultrasound was reviewed. A team composed of specialists in neurology, physiatry, anesthesiology, orthopedic surgery, and vascular surgery used this as the basis for describing standardized techniques for performing brachial plexus ultrasound. Four standard views, along with other supplemental views, are described for the evaluation of the brachial plexus. An illustrative case is presented. Ultrasound is a high-resolution point of care diagnostic tool that allows assessment of structural pathology affecting the brachial plexus. Muscle Nerve 58: 618-624, 2018.

Sonographic Visualization of Thenar Motor Branch of the Median Nerve: A Cadaveric Validation Study.

BACKGROUND: The thenar motor branch (TMB) of the median nerve may be affected in carpal tunnel syndrome and can be injured during carpal tunnel surgery. Although ultrasound has been used to identify small nerves throughout the body, the sonographic evaluation of the TMB has not been investigated formally. OBJECTIVE: To document the ability of ultrasound to visualize the TMB of the median nerve in an unembalmed cadaveric model. DESIGN: Prospective laboratory investigation. SETTING: Procedural skills laboratory at a tertiary medical center. METHODS: On the basis of anatomical descriptions, dissection and clinical experience, a technique was developed to sonographically identify the presumed TMB of the median nerve at the distal carpal tunnel. A single, experienced examiner then identified the presumed TMB in 10 unembalmed, cadaveric upper limb specimens (4 right, 6 left) obtained from 9 donors (4 male, 5 female) ages 76-85 years with body mass indices of 18.2-29.5 kg/m2 with both 12-3 MHZ and 16-7 MHz linear array transducers. The same examiner then injected 0.2-0.3 mL of diluted colored latex into and around the presumed TMB using direct ultrasound guidance. At a minimum of 24 hours postinjection, specimens were dissected under loupe magnification to determine the location of the latex injectate. MAIN OUTCOME MEASURE: The location of latex injectate relative to the anatomically identified TMB. RESULTS: A vertical, linear, hypoechogenic region was sonographically identified arising from the median nerve at the distal carpal tunnel in all 10 specimens and was hypothesized to represent the vertical segment of the TMB. Both transducers allowed identification of the TMB, although localization was subjectively facilitated by the higher frequency transducer. All 10 sonographically guided injections placed latex into and around the TMB of the median nerve, confirming that ultrasound had accurately identified the TMB. CONCLUSIONS: Sonographic evaluation of the TMB of the median nerve is technically feasible and should be considered when clinically indicated. Further research and clinical experience is necessary to define the role of sonographic TMB imaging in the evaluation and management of patients with carpal tunnel syndrome. LEVEL OF EVIDENCE: IV.

Ultrasound-Guided Peripheral Nerve Procedures.

Ultrasound guidance allows real-time visualization of the needle in peripheral nerve procedures, improving accuracy and safety. Sonographic visualization of the peripheral nerve and surrounding anatomy can provide valuable information for diagnostic purposes and procedure enhancement. Common procedures discussed are the suprascapular nerve at the suprascapular notch, deep branch of the radial nerve at the supinator, median nerve at the pronator teres and carpal tunnel, lateral cutaneous nerve of the thigh, superficial fibular nerve at the leg, tibial nerve at the ankle, and interdigital neuroma. For each procedure, the indications, relevant anatomy, preprocedural scanning technique, and injection procedure itself are detailed.

Ultrasound evaluation of focal neuropathies in athletes: a clinically-focused review.

Focal neuropathies represent a rare but clinically important and potentially challenging aetiology of pain in athletes. Diagnostic ultrasound is commonly used in the evaluation of nerve entrapments, and has several advantages over other imaging modalities, including high resolution, portability, lack of ionising radiation, low cost, point-of-care access, ease of contralateral comparison and capability of Doppler and dynamic imaging techniques. In this review, we discuss the use of ultrasound for the evaluation of injuries to the brachial plexus including 'stingers,' suprascapular nerve, ulnar nerve, radial nerve, common fibular nerve, tibial nerve and interdigital nerves of the foot at selected common sites of entrapment.

Electrodiagnosis of plexopathy.

Electrodiagnostic evaluation of the brachial and lumbosacral plexus can be challenging even to an experienced practitioner. Detailed attention to anatomy and correlation with the history and physical examination results are needed to have a comprehensive differential diagnosis and to develop reliable conclusions. Electrophysiologic techniques, when applied appropriately, provide invaluable functional information after a plexus injury. Electrodiagnostic evaluation of a plexus injury should be systematic and comprehensive to provide the maximum precision for localization, extent of involvement, and severity of injury.

Acute common peroneal neuropathy due to hand positioning in normal labor and delivery.

BACKGROUND: Foot drop has been described as an infrequent complication from common peroneal nerve injury related to external compression and forceful knee flexion while pushing during vaginal delivery. Past recommendations include placing the hands at the posterior thighs rather than the legs to avoid this complication. CASE: A 32-year-old woman developed unilateral foot drop after vaginal delivery. Electromyography was diagnostic for an acute compression neuropathy of the common peroneal nerve above the knee. CONCLUSION: The patient's likely mechanism of injury occurred during delivery from external compression by the patient's dominant hand to the distal posterior thigh while under epidural anesthesia. Labor and delivery teams should be aware that nerve injury is also possible at the distal thigh with excessive external pressure.

The use of ultrasound in guiding musculoskeletal interventional procedures.

There has been an increase in the use of ultrasound (US) to help guide interventional procedures involving the musculoskeletal system. To perform these procedures safely and accurately, two steps must occur. First, the appropriate structure must be localized using diagnostic US imaging. Second, a needle must be guided under constant visualization toward the targeted tissue. Although US imaging can help place the needle and, hence, therapeutic medication more accurately, there is still debate about whether or not image-guided procedures result in improved outcomes. This article discusses the advantages and disadvantages of performing US-guided injections and describes injection principles and techniques. Studies examining the efficacy of US-guided procedures are reviewed.

Phrenic nerve stimulation in the evaluation of ventilator-dependent individuals with C4- and C5-level spinal cord injury.

Three individuals with C4 or C5 spinal cord injuries (SCI) were seen in follow-up for management of their late complications, which included impaired ventilation. Electrodiagnostic studies were performed on all three as part of the assessment of the function of their phrenic nerves and diaphragm muscles in relation to their need for mechanical ventilator support. Each patient had evidence of lower-motor neuron injury to the phrenic nerves. Two of the patients who initially displayed small-amplitude (<0.1 mV) compound muscle action potentials (CMAP) bilaterally were later reevaluated during the course of their observation in the outpatient rehabilitation clinic. The CMAP amplitude of the diaphragm increased in these two cases during the 3-11 mos after SCI. Evidence of nerve recovery occurred in parallel with improvements in pulmonary function testing and was followed by successful weaning from the ventilator. These individuals both gained ventilator independence after the CMAP amplitude of least one hemidiaphragm was >0.4 mV. In the third case, early failure of ventilator weaning was reported to the patient as a poor prognostic sign. At the time of our first evaluation 11 mos after injury, a CMAP of 1.0 mV was seen on the right, with an absent response on the left. In case 3, the needle electromyogram demonstrated voluntary active motor unit action potentials that provided additional electrophysiologic support for phrenic nerve function. Phrenic nerve-conduction studies can provide useful measures in assessing the recovery of lower-motor neuron diaphragm function in relation to impaired ventilation in individuals with C4- or C5-level SCI.

Management of common running injuries.

Runners are susceptible to a variety of potential injuries because of the considerable stress of this activity. This can create a challenge for the treating practitioner; however, many of the common ailments occur in a reasonably predictable pattern. A careful history and physical examination are necessary for accurate diagnosis. Having a good understanding of these injuries as well of the role of biomechanical factors and common training errors can assist with appropriate care. Further development in the knowledge of soft tissue trauma, gait, and diagnostic and therapeutic modalities should lead to improved management of the injuries facing these athletes.

An instance of an atypical intraspinal cyst presenting as S1 radiculopathy: a case report and brief review of pathophysiology.

Intraspinal cysts are rare, but typically they originate from a degenerate zygapophyseal joint. These cysts have been commonly referred to as juxtafacet cysts and occur concomitantly with lumbar and occasionally lower-limb radicular pain. Documented cases have shown pseudoarthroses developing from nonhealing pars defects. Histologic analyses have found synovial tissue within these fibrocartilaginous accumulations. We present a case of S1 radiculopathy indicated by an intraspinal pseudocyst arising as a complication of a chronic spondylolytic defect. A brief review of the related pathophysiology is also included.