Ultrasonographic Identification of Fibromuscular Bands Associated with Neurogenic Thoracic Outlet Syndrome: The "Wedge-Sickle" Sign

Diagnostic ultrasonography of upper extremity dynamic compressive neuropathies in athletes: A narrative review

PURPOSE

This narrative review identifies and summarizes current evidence for diagnostic ultrasonographic evaluation of upper extremity dynamic compressive neuropathies affecting athletes.

METHODS

Relevant literature was identified using the PubMed database and then summarized.

RESULTS

The compressive neuropathies affecting athletes we identified included: neurogenic thoracic outlet syndrome, pectoralis minor syndrome, quadrilateral space syndrome, suprascapular nerve entrapment, proximal median nerve entrapment or bicipital aponeurosis/lacertus fibrosus (lacertus syndrome), radial tunnel syndrome, and cubital tunnel syndrome. Symptoms may develop only during specific sport activity, after specific sport-related trauma, or in setting of overuse during sport. Diagnostic ultrasound strategies assessing compressive neuropathies focus on static evaluation of nerves and surrounding structures, as well as dynamic evaluation of these structures in certain degrees of shoulder abduction, elbow flexion, or forearm pronation.

CONCLUSION

Ultrasonography can be used as a diagnostic tool in assessing upper extremity dynamic compressive neuropathies. Ultrasound allows for dynamic evaluation of these rare conditions, especially for athletes who primarily develop symptoms during movement or participation in sport.

Don't be perplexed by the plexus! A practical approach to brachial plexus ultrasound

Ultrasound is as accurate as MRI in the detection of most brachial pathologies but tends to be underutilized in clinical practice compared to MRI. The main reason for this under-usage is a relative lack of knowledge regarding how to perform brachial plexus ultrasound and a lack of awareness of the ultrasound appearances of brachial pathologies. This review serves to re-address this imbalance by providing a practical overview on how to perform brachial plexus ultrasound as well as highlighting the ultrasound appearances of common pathologies likely to be encountered in everyday clinical practice.

Magnetic resonance neurography in the diagnosis of neurological subtypes of thoracic outlet syndrome

Neurological thoracic outlet syndrome (TOS) can be challenging to diagnose, particularly given its described subtypes of neurogenic TOS (NTOS) and disputed TOS (DTOS) that exhibit variable clinical presentations and etiologies. The diagnostic workup of TOS often includes magnetic resonance neurography (MRN) of the brachial plexus. Specific MRN imaging modifications for TOS evaluation are required to maximize spatial and contrast resolution to increase the conspicuity of nerve segments and their relationships to surrounding osseous structures. Dynamic assessment with arm positioning is used to evaluate outlet narrowing and compression of the plexus. Individual nerve segments are interrogated for their longitudinal and cross-sectional morphologies and signal characteristics. In patients with NTOS, MRN may reveal focal impingement of the C8/T1 nerve roots and/or lower trunk with accompanying abnormal T2-weighted signal hyperintensity. Predisposing anatomical entities include cervical ribs, rib synostoses, hypertrophic callous following clavicular fracture, remnant first thoracic rib from prior incomplete resection, and variable perineural scarring. In comparison, DTOS patients frequently demonstrate signal hyperintensity and enlargement of the mid plexus (trunk and division level), with narrowing of the costoclavicular interval. Following comprehensive diagnostic workup that frequently includes electrodiagnostic testing, patients are directed to different management pathways. Nonsurgical management is considered for all cases of DTOS; all patients with NTOS or DTOS who fail conservative treatment warrant referral for a surgical opinion. If surgery is pursued, MRN can be helpful in preoperative planning.

Diagnostic and Therapeutic Approach to Thoracic Outlet Syndrome

Thoracic outlet syndrome (TOS) is a group of symptoms caused by the compression of neurovascular structures of the superior thoracic outlet. The knowledge of its clinical presentation with specific symptoms, as well as proper imaging examinations, ranging from plain radiographs to ultrasound, computed tomography and magnetic resonance imaging, may help achieve a precise diagnosis. Once TOS is recognized, proper treatment may comprise a conservative or a surgical approach.

Sports-related peripheral nerve injuries of the upper limb

Peripheral nerve injuries in athletes affect the upper limb more commonly than the lower limb. Common mechanisms include compression, traction, laceration, and ischemia. Specific sports can have unique mechanisms of injury and are more likely to be associated with certain neuropathies. Familiarity with these sport-specific variables and recognition of the common presentations of upper limb neuropathic syndromes are important in assessing an athlete with a suspected peripheral nerve injury. Evaluation may require imaging modalities and/or electrodiagnostic testing to confirm a nerve injury. In some cases, diagnostic injections may be needed to differentiate neuropathic versus musculoskeletal etiology. Early and accurate diagnosis is essential for treatment/management and increases the likelihood of a safe return-to-sport and avoidance of long-term functional consequences. Most nerve injuries can be treated conservatively, however, severe or persistent cases may require surgical intervention. This monograph reviews key diagnostic, management, and preventative strategies for sports-related peripheral nerve injuries involving the upper limb.

Neurogenic thoracic outlet syndrome and controversies in diagnosis and management

Compression of the neurovascular structures at the level of the scalene triangle and pectoralis minor space is rare, but increasing awareness and understanding is allowing for the treatment of more individuals than in the past. We outlined the recognition, preoperative evaluation, and treatment of patients with neurogenic thoracic outlet syndrome. Recent work has illustrated the role of imaging and centrality of the physical examination on the diagnosis. However, a fuller understanding of the spatial biomechanics of the shoulder, scalene triangle, and pectoralis minor musculotendinous complex has shown that, although physical therapy is a mainstay of treatment, a poor response to physical therapy with a sound diagnosis should not preclude decompression. Modes of failure of surgical decompression stress the importance of full resection of the anterior scalene muscle and all posterior rib impinging elements to minimize the risk of recurrence of symptoms. Neurogenic thoracic outlet syndrome is a rare but critical cause of disability of the upper extremity. Modern understanding of the pathophysiology and evaluation have led to a sounder diagnosis. Although physical therapy is a mainstay, surgical decompression remains the gold standard to preserve and recover function of the upper extremity. Understanding these principles will be central to further developments in the treatment of this patient population.

[Long-Term Outcomes after Surgery of the Neurogenic Thoracic-Outlet Syndrome in Adolescents]

BACKGROUND

Neurogenic Thoracic Outlet Syndrome (nTOS) describes a complex of symptoms caused by the compression of neural structures at the upper thoracic outlet. Typical symptoms include pain, numbness and motor weakness of the affected extremity. The incidence of nTOS is 2-3 per 100,000 and is highest between the ages of 25 and 40. There are only a few studies evaluating the surgical outcomes of nTOS in adolescent patients. In particular, there is a lack of long-term data.

MATERIALS AND METHODS

In a retrospective study of nTOS cases receiving surgical treatment in our clinic between 2002 and 2021, eight patients between 15 and 18 years of age were included. Demographic data, risk factors, clinical symptoms, clinical functional tests, neurophysiological, radiological and intraoperative findings were evaluated. Postoperative data were recorded using a standardised questionnaire. Decompression of the inferior truncus and the C8 and Th1 nerve roots was performed via a supraclavicular approach.

RESULTS

The average duration of symptoms before surgery was two years. Of the eight patients who underwent surgery, six answered the written questionnaire and could be analysed for the study. The average follow-up was nine years (1-18 years). After surgery, all patients experienced pain reduction; three were pain-free in the long run and five no longer required pain medication. Strength improved in all patients, but two patients still had mild motor deficits. Sensory disturbances were reduced in all patients, but residual hypoesthesia persisted in five. With regard to overhead work, half of the patients had no impairment after surgery. All patients were able to work at the time of the survey. Half of the patients pursued their sports activities without impairment, while mild impairment was reported by the other half.

CONCLUSION

nTOS in adolescents is a rare compression syndrome. Decompression of the lower parts of the brachial plexus using a supraclavicular approach without resection of the first rib is an adequate treatment. This retrospective study showed that a reduction in pain was achieved in all patients. In some patients, slight sensory and motor disturbances as well as a certain restriction in overhead work persisted. Patients were able to return to sports.

The role of imaging in focal neuropathies

Electrodiagnostic testing (EDX) has been the diagnostic tool of choice in peripheral nerve disease for many years, but in recent years, peripheral nerve imaging has been used ever more frequently in daily clinical practice. Nerve ultrasound and magnetic resonance (MR) neurography are able to visualize nerve structures reliably. These techniques can aid in localizing nerve pathology and can reveal significant anatomical abnormalities underlying nerve pathology that may have been otherwise undetected by EDX. As such, nerve ultrasound and MR neurography can significantly improve diagnostic accuracy and can have a significant effect on treatment strategy. In this chapter, the basic principles and recent developments of these techniques will be discussed, as well as their potential application in several types of peripheral nerve disease, such as carpal tunnel syndrome (CTS), ulnar neuropathy at the elbow (UNE), radial neuropathy, brachial and lumbosacral plexopathy, neuralgic amyotrophy (NA), fibular, tibial, sciatic, femoral neuropathy, meralgia paresthetica, peripheral nerve trauma, tumors, and inflammatory neuropathies.

Diagnosis of thoracic outlet syndrome with the lower trunk compression of brachial plexus by high-frequency ultrasonography

BACKGROUND

Thoracic outlet syndrome (TOS) with the lower trunk compression of brachial plexus (BP) is difficult to diagnosis. This study aimed to summarize the features of thoracic outlet syndrome (TOS) with the lower trunk compression of brachial plexus observed on high-frequency ultrasonography (HFUS).

METHODS

The ultrasound data of 27 patients who had TOS with the lower trunk compression of brachial plexus were collected and eventually confirmed by surgery. The imaging data were compared, and the pathogenesis of TOS was analyzed on the basis of surgical data.

RESULTS

TOS occurred predominantly in females (70.4%). Most cases had unilateral involvement (92.6%), mainly on the right side (66.7%). The HFUS features of TOS can be summarized as follows: (1) Lower trunk compression. HFUS revealed focal thinning that reflected compression at the level of the lower trunk; furthermore, the distal part of the nerve was thickened for edema (Affected side: 0.49 ± 0.12 cm vs. Healthy side: 0.38 ± 0.06, P = 0.009), and the cross-sectional area of brachial plexus cords was markedly greater on the injured side than on the healthy side (0.95 ± 0.08 cm² vs. 0.65 ± 0.11 cm², P = 0.004). (2) Hyperechoic fibromuscular bands behind the compressed nerve (mostly the scalenus minimus muscle). (3) Abnormal bony structures: cervical ribs or elongated transverse processes of the 7th cervical vertebra (C7). Surgical results showed that the etiological factors contributing to TOS were (1) muscle hypertrophy and/or fibrosis (100%) and (2) cervical ribs/elongated C7 transverse processes (20.7%).

CONCLUSION

TOS with the lower trunk compression of brachial plexus can be diagnosed accurately and reliably by high-frequency ultrasound.

General Overview and Diagnostic (Imaging) Techniques for Neurogenic Thoracic Outlet Syndrome

Thoracic outlet syndrome is an uncommon and controversial syndrome. Three different diagnoses can be made based on the compressed structure, arterial TOS, venous TOS, and neurogenic TOS, though combinations do exist as well. Diagnosing NTOS is difficult since no specific objective diagnostic modalities exist. This has resulted in a lot of controversy in recent decades. NTOS remains a clinical diagnosis and is mostly diagnosed based on the exclusion of an extensive list of differential diagnoses. To guide the diagnosis and treatment of TOS, a group of experts published the reporting standards for TOS in 2016. However, a consensus was not reached regarding a blueprint for a daily care pathway in this document. Therefore, we constructed a care pathway based on the reporting standards for both the diagnosis and treatment of NTOS patients. This care pathway includes a multidisciplinary approach in which different diagnostic tests and additional imaging techniques are combined to diagnose NTOS or guide patients in their treatment for differential diagnoses. The aim of the present work is to discuss and explain the diagnostic part of this care pathway.

Current Concepts in the Management of Neurogenic Thoracic Outlet Syndrome: A Review

Thoracic outlet syndrome is a constellation of signs and symptoms due to compression of the neurovascular bundle of the upper limb. In particular, neurogenic thoracic outlet syndrome can present with a wide constellation of clinical manifestations ranging from pain to paresthesia of the upper extremity, resulting in a challenge to correctly diagnose this syndrome. Treatment options range from nonoperative treatment, such as rehabilitation and physical therapy, to surgical correction, such as decompression of the neurovascular bundle.

Methods

Following a systematic review of the literature, we describe the need for a thorough patient history, physical examination, and radiologic images which have been reported to correctly diagnose neurogenic thoracic outlet syndrome. Additionally, we review the various surgical techniques recommended to treat this syndrome.

Results

Postoperative functional outcomes have been shown to be more favorable in arterial and venous thoracic outlet syndrome (TOS) patients when compared with neurogenic TOS patients, likely due to the ability to completely remove the site of compression in cases of vascular TOS as compared with incomplete decompression in neurogenic TOS.

Conclusions

In this review article, we provide an overview of the anatomy, etiology, diagnostic modalities, and current treatment options of correcting neurogenic TOS. Additionally, we offer a detailed step-by-step technique of the supraclavicular approach to the brachial plexus, a preferred approach for decompressing neurogenic TOS.

Elective brachial plexus decompression in neurogenic thoracic outlet syndrome

We aimed to evaluate functional outcome following elective brachial plexus decompression by compressive fibrous band resection and limited on-demand bone abnormality resection in patients with neurogenic thoracic outlet syndrome (N-TOS). A retrospective continuous observational study was conducted in 17 patients (15 women and 2 men), with a mean age of 42 years, operated on between 2013 and 2021. Twenty brachial plexus decompressions were performed, for 13 objective and 7 subjective N-TOSs, including 3 recurrent N-TOSs. At last follow-up, outcomes were evaluated in terms of residual pain, paresthesia and hand motor deficit, plus patient-reported assessment and Quick-DASH functional scoring. No postoperative complications occurred. At a median follow-up of 12 months (range 6-48 months), complete pain relief and paresthesia resolution were found in 11/15 and 9/14 cases, respectively. All patients reported that their symptoms had improved. In contrast, hand muscle atrophy persisted in all cases (n = 11). Sensorimotor recovery seemed to be poorer and mean Quick-DASH score better in objective than subjective N-TOS patients. Elective brachial plexus decompression seemed to be a safe procedure, providing constant improvement in subjective symptoms related to lower trunk irritation. However, nerve release did not provide hand muscle recovery in patients with objective N-TOS. LEVEL OF EVIDENCE: IV.

Thoracic Outlet Syndrome Part I: Systematic Review of the Literature and Consensus on Anatomy, Diagnosis, and Classification of Thoracic Outlet Syndrome by the European Association of Neurosurgical Societies' Section of Peripheral Nerve Surgery

BACKGROUND

Although numerous articles have been published not only on the classification of thoracic outlet syndrome (TOS) but also on diagnostic standards, timing, and type of surgical intervention, there still remains some controversy because of the lack of level 1 evidence. So far, attempts to generate uniform reporting standards have not yielded conclusive results.

OBJECTIVE

To systematically review the body of evidence and reach a consensus among neurosurgeons experienced in TOS regarding anatomy, diagnosis, and classification.

METHODS

A systematic literature search on PubMed/MEDLINE was performed on February 13, 2021, yielding 2853 results. Abstracts were screened and classified. Recommendations were developed in a meeting held online on February 10, 2021, and refined according to the Delphi consensus method.

RESULTS

Six randomized controlled trials (on surgical, conservative, and injection therapies), 4 "guideline" articles (on imaging and reporting standards), 5 observational studies (on diagnostics, hierarchic designs of physiotherapy vs surgery, and quality of life outcomes), and 6 meta-analyses were identified. The European Association of Neurosurgical Societies' section of peripheral nerve surgery established 18 statements regarding anatomy, diagnosis, and classification of TOS with agreement levels of 98.4 % (±3.0).

CONCLUSION

Because of the lack of level 1 evidence, consensus statements on anatomy, diagnosis, and classification of TOS from experts of the section of peripheral nerve surgery of the European Association of Neurosurgical Societies were developed with the Delphi method. Further work on reporting standards, prospective data collections, therapy, and long-term outcome is necessary.

Combined nerve and vascular ultrasound in thoracic outlet syndrome: A sensitive method in identifying the site of neurovascular compression

We investigated the diagnostic utility of combined nerve and vascular ultrasound in thoracic outlet syndrome (TOS) in a retrospective cohort study on two sites, involving 167 consecutive patients with the clinical symptoms suggestive of neurogenic and/or vascular TOS, and an age- and sex-matched control group. All patients and control subjects underwent nerve ultrasound of the supraclavicular brachial plexus to look for fibromuscular anomalies / compression of the brachial plexus in the scalenic region, and vascular ultrasound of the infraclavicular subclavian artery with the arm in neutral and abducted position, serving as an indicator for costoclavicular compression of the neurovascular bundle. Based on clinical symptoms, neurogenic TOS (81%) was the most frequent type of TOS, followed by combined neurogenic and arterial TOS (8%). The frequency of abnormal nerve and/or vascular ultrasound findings differed significantly from the control group (P<0.00001). The pooled sensitivity was 48% for nerve ultrasound, 85% for vascular ultrasound, and 94% when combined. Among the findings, the fibromuscular ‘wedge-sickle sign’, indicating compression of the lower trunk in the scalenic region by a congenital fibromuscular anomaly (e.g. Roos ligaments), showed the highest specificity (100%). A bony ‘wedge-sickle sign’ was also delineated, where lower trunk compression is caused by the neck of the 1^st rib. As implied by the higher sensitivity of vascular ultrasound, the most common site of compression was the costoclavicular space, but multilevel compression was also frequently observed. In summary, combined nerve and vascular ultrasound is a sensitive and reliable method to support the diagnosis of TOS. It can also identify the site(s) of compression, with obvious therapeutic consequences.

Neurogenic thoracic outlet syndrome in the overhead and throwing athlete: A narrative review

Thoracic outlet syndrome is an important cause of shoulder pain and dysfunction due to compression of neurovascular structures as they traverse the thoracic outlet. Symptoms are most commonly due to compression of the brachial plexus called neurogenic thoracic outlet syndrome (nTOS). Throwing athletes are at increased risk of nTOS because of a variety of biomechanical factors. However, because nTOS symptoms are often nonspecific, delayed diagnosis is common. Neurogenic thoracic outlet largely remains a diagnosis of exclusion with advanced imaging ruling out vascular involvement and diagnostic injections gaining favor in helping localize sites of compression. Although rehabilitation alone may improve symptoms in some athletes, many require surgical treatment for long-term relief. This generally entails decompression of the thoracic outlet by some combination of muscle release, brachial plexus neurolysis, and first rib resection. Outcomes tend to be successful in athletes with most achieving resolution of symptoms and return to athletic activity. NTOS is an important cause of shoulder pain and dysfunction in throwing athletes. The history and physical examination should focus on activities that exacerbate symptoms. Treatment of nTOS generally requires surgical intervention and allows throwing athletes to return to sport.

Thoracic Outlet Syndrome: Single Center Experience on Robotic Assisted First Rib Resection and Literature Review

BACKGROUND

Thoracic outlet syndrome (TOS) is a pathological condition caused by a narrowing between the clavicle and first rib leading to a compression of the neurovascular bundle to the upper extremity. The incidence of TOS is probably nowadays underestimated because the diagnosis could be very challenging without a thorough clinical examination along with appropriate clinical testing. Beside traditional supra-, infraclavicular or transaxillary approaches, the robotic assisted first rib resection has been gaining importance in the last few years.

METHODS

We conducted a retrospective cohort analysis of all patients who underwent robotic assisted first rib resection due to TOS at Lucerne Cantonal Hospital and then we performed a narrative review of the English literature using PubMed, Cochrane Database of Systematic Reviews and Scopus.

RESULTS

Between June 2020 and November 2021, eleven robotic assisted first rib resections were performed due to TOS at Lucerne Cantonal Hospital. Median length of stay was 2 days (Standard Deviation: +/- 0.67 days). Median surgery time was 180 min (Standard Deviation: +/- 36.5). No intra-operative complications were reported.

CONCLUSIONS

Robotic assisted first rib resection could represent a safe and feasible option in expert hands for the treatment of thoracic outlet syndrome.

Thoracic Outlet decompression Surgery for Gilliatt-Sumner Hand as presentation of neurogenic thoracic outlet syndrome

INTRODUCTION

Chronic compression of the inferior trunk of the brachial plexus can result in severe pain and progressive atrophy and weakness of the musculature of the forearm and hand, known as Gilliatt-Sumner Hand (GSH). The objective of treatment in these patients is to stop further atrophy and pain. Restoration of motor function is thought to be seldom achieved. The aim of this contemporary case series is to describe diagnosis, treatment and outcomes of surgery in GSH.

METHODS

All patients referred between January 2017 and May 2021 with visible signs of a GSH were included. Visible GSH signs were defined as muscle atrophy of the abductor digiti minimi (ADM), abductor pollicis brevis (APB), and/or interosseous musculature. Additional electrodiagnostic assessment (EDx) and high-resolution ultrasound (HRUS) were performed in all patients. All diagnosed GSH patients underwent thoracic outlet decompression (TOD) surgery by transaxillary (TA) or supraclavicular (SC) approach. Outcomes were measured with the TOS disability scale, Cervical Brachial Score Questionnaire (CBSQ), Disability of the Arm, Shoulder, and Hand (DASH) score and patient reported outcome of motor function, measured with a numerated rating scale score (NRS). The standardized Elevated Arm Stress Test (sEAST) was used to assess motor function before and after TOD.

RESULTS

Twenty patients were referred to our center with visible signs of a GSH. Clinical examination showed atrophy of the ADM, APB and interosseous musculature in all patients. EDx showed plexopathy of the lower brachial plexus in all patients. HRUS showed an indented inferior trunc of the brachial plexus (so called "wedge sickle sign" WSS) in 18 (90%) patients. Surgical treatment was performed in 17 patients (15 TA-TOD, 2 SC TOD). Three patients refrained from surgical treatment. The median follow-up interval was 15.0 (IQR 14.0) months. The TOS disability scale improved significant (Preoperative: mean 6.31, CI [5.49 - 7.13]; postoperative: mean 4.25, CI [2.80 - 5.70], p=0.026). The same was seen for the CBSQ scores (preoperative mean 77.75, CI [66.63 - 88.87]; postoperative mean 42.65, CI [24.77 - 60.77], p= 0.001) and DASH scores (preoperative mean 59.13, CI [51.49 - 66.77]; postoperative mean 40.96, CI [24.41 - 57.51]; p= 0.032. The NRS for muscle weakness and sEAST showed no statistical difference before and after TOD comparing the whole group (NRS muscle weakness preoperative mean: 6.22, CI [4.31 - 8.14]; postoperative mean: 5.11, CI [3.25 - 6.97]; p= 0.269). However, 4 (23.52%) patients had a 50% or more decrease in NRS for muscle weakness and a minimum increase of 20% in total and average force on the sEAST measurement. The NRS for numbness showed a statistically significant decrease for the whole group (preoperative mean: 5.67, CI [4.18 - 7.16]; postoperative mean: 3.33 [1.37-5.29]; p=0.029).

CONCLUSION

A combination of physical examination, EDx and HRUS studies can differentiate GSH from differential diagnoses. HRUS appears has the advantage over EDx studies in confirming GSH by visualization of compression of the brachial plexus. TOD surgery will stop the progressive muscle atrophy and significantly reduce NTOS complaints and in some patients, motor function will recover.

Evaluation and Management of Neurogenic Thoracic Outlet Syndrome with an Overview of Surgical Approaches: A Comprehensive Review

Neurogenic thoracic outlet syndrome (NTOS) represents a disorder believed to involve compression of one or more neurovascular elements as they exit the thoracic outlet. This comprehensive literature review will focus on the occurrence, classification, etiology, clinical presentation, diagnostic measures, and both nonoperative and operative therapies for NTOS. NTOS represents the most common subtype of thoracic outlet syndrome and can significantly impair quality of life. Botulinum toxin injection into the anterior scalene muscle, or even the middle scalene or pectoralis minor muscles, can reduce the symptoms of this syndrome. The best available evidence for botulinum toxin therapy to the cervicothoracic muscles supports the value of this treatment for reducing pain in the affected extremity, and for an approximate duration of 2 months or more. Surgical approaches and newer minimally invasive surgical approaches offer high rates of improvement in select centers.

Variability in electrodiagnostic findings associated with neurogenic thoracic outlet syndrome

Introduction/Aims

Neurogenic thoracic outlet syndrome (NTOS) is a heterogeneous and often disputed entity. An electrodiagnostic pattern of T1 > C8 axon involvement is considered characteristic for the diagnosis of NTOS. However, since the advent of high‐resolution nerve ultrasound (US) imaging, we have encountered several patients with a proven entrapment of the lower brachial plexus who showed a different, variable electrodiagnostic pattern.

Methods

In this retrospective case series, 14 patients with an NTOS diagnosis with a verified source of compression of the lower brachial plexus and abnormal findings on their electrodiagnostic testing were included. Their medical records were reviewed to obtain clinical, imaging, and electrodiagnostic data.

Results

Seven patients showed results consistent with the “classic” T1 axon  > C8 pattern of involvement. Less typical findings included equally severe involvement of T1 and C8 axons, more severe C8 involvement, pure motor abnormalities, neurogenic changes on needle electromyography in the flexor carpi radialis and biceps brachii muscles, and one patient with an abnormal sensory nerve action potential (SNAP) amplitude for the median sensory response recorded from the third digit. Patients with atypical findings on electrodiagnostic testing underwent nerve imaging more often compared to patients with classic findings (seven of seven patients vs. five of seven respectively), especially nerve ultrasound.

Discussion

When there is a clinical suspicion of NTOS, an electrodiagnostic finding other than the classic T1 > C8 pattern of involvement does not rule out the diagnosis. High resolution nerve imaging is valuable to diagnose additional patients with this treatable condition.

See Editorial on pages 4‐6 in this issue.

Clinico-radiological review of peripheral entrapment neuropathies - Part 1 upper limb

PURPOSE

This article aims to review the pertinent anatomy, etiopathogenesis, current clinical and radiological concepts and principles of management in case of upper limb entrapment neuropathies.

METHODS

The review is based on critical analysis of the existing literature as well as our experience in dealing with entrapment neuropathies.

RESULTS

Entrapment neuropathies of the upper limb peripheral nerves are common conditions that are often misdiagnosed because of their varying clinical presentations and lack of standardized diagnostic methods. Clinical assessment and electrodiagnostic studies have been the mainstay; however, imaging techniques have provided newer insights into the pathophysiology of these entities, leading to a paradigm shift in their diagnosis and management. The current best practice protocols for entrapment syndromes are constantly evolving with increasing emphasis on the role high-resolution ultrasound and magnetic resonance imaging. Many imaging criteria are described and we have tried to present the most validated measurements for diagnosing entrapment neuropathies.

CONCLUSION

It is imperative for a clinical radiologist to be familiar with the etiopathogenesis and clinical features of these conditions, in addition to being thorough with the anatomy and the latest imaging strategies.

Current and future applications of ultrasound imaging in peripheral nerve disorders

Neuromuscular ultrasound (NMUS) is a rapidly evolving technique used in neuromuscular medicine to provide complimentary information to standard electrodiagnostic studies. NMUS provides a dynamic, real time assessment of anatomy which can alter both diagnostic and management pathways in peripheral nerve disorders. This review describes the current and future techniques used in NMUS and details the applications and developments in the diagnosis and monitoring of compressive, hereditary, immune-mediated and axonal peripheral nerve disorders, and motor neuron diseases. Technological advances have allowed the increased utilisation of ultrasound for management of peripheral nerve disorders; however, several practical considerations need to be taken into account to facilitate the widespread uptake of this technique.

Sonographic Pearls for Imaging the Brachial Plexus and Its Pathologies

The brachial plexus (BP) is a complicated neural network, which may be affected by trauma, irradiation, neoplasm, infection, and autoimmune inflammatory diseases. Magnetic Resonance Imaging is the preferred diagnostic modality; however, it has the limitations of high cost and lack of portability. High-resolution ultrasound has recently emerged as an unparalleled diagnostic tool for diagnosing postganglionic lesions of the BP. Existing literature describes the technical skills needed for prompt ultrasound imaging and guided injections for the BP. However, it remains particularly challenging for beginners to navigate easily while scanning its different parts. To address this, we share several “clinical pearls” for the sonographic examination of the BP as well as its common pathologies.

An overview of the findings of dynamic upper limbs’ arterial and venous duplex in cases of vascular thoracic outlet syndrome

Background

To describe the findings of the dynamic upper limb arterial and venous duplex in the assessment of vascular compression in cases of VTOS. This study was conducted on 58 patients with VTOS; they were evaluated by dynamic duplex examination.

Results

Vascular compression was subdivided into a venous compression that was detected in (84.4%,n = 49), arterial compression that was seen in (1.7%,n = 1), and combined arterial and venous compression that was present in (13.7%,n = 8); bilateral compression was existing in (94.4%,n = 55), compression at the scalene triangle was seen in (1.7%,n = 1), at the costo-clavicular space was seen in (91.3%,n = 53), and at the retro-pectoral space was depicted in (8.6%,n = 5).

Complicated arterial compression was detected in (1.7%,n = 1), whereas venous complications were seen in (6.8%,n = 4).

Conclusion

Dynamic duplex ultrasound offered a simple, noninvasive, and quick technique that can help in the evaluation of the vascular thoracic outlet syndrome without exposure to ionizing radiation or contrast media administration like that in CT; nevertheless, it is done with the patient in the upright position, thus avoiding the high false-negative results associated with the supine position that is used in the CT and MRI studies.

A Novel Approach for Imaging of Thoracic Outlet Syndrome Using Contrast-Enhanced Magnetic Resonance Angiography (CE-MRA), Short Inversion Time Inversion Recovery Sampling Perfection with Application-Optimized Contrasts Using Different Flip Angle Evolutions (T2-STIR-SPACE), and Volumetric Interpolated Breath-Hold Examination (VIBE)

Background

The aim of this study was to introduce a novel method combining contrast-enhanced magnetic resonance angiography (CE-MRA), short inversion time inversion recovery sampling perfection with application-optimized contrasts using different flip angle evolutions (T2-STIR-SPACE) and volumetric interpolated breath-hold examination (VIBE) sequences in the assessment of thoracic outlet syndrome (TOS).

Material/Methods

CE-MRA, T2-STIR-SPACE, and VIBE techniques were employed to evaluate neurovascular bundles in 27 patients clinically suspected of TOS. Images were evaluated to determine the cause of neurovascular bundle compression. Surgical exploration was performed in patients with abnormal magnetic resonance imaging (MRI) results.

Results

Twenty patients were found to be abnormal: 6 cases showed only neurogenic TOS and the correlates included infraclavicular hemangiomas (n=1) and transverse cervical artery (n=5). Arterial-neurogenic TOS was found in 4 cases, including subclavian lymph node metastasis from breast cancer (n=3) and schwannoma (n=1). Arterial-venous-neurogenic TOS was found in 1 subject, and the correlates included a fibrous band from the cervical rib and elongated C7 transverse process. In this case, the subclavian artery/vein was compressed dynamically. Venous–neurogenic TOS was noted in one subject. Nine patients were considered as post-traumatic TOS, including brachial plexus edema (n=3), the brachial plexus rupture (n=2), peri-brachial plexus effusion (n=3), and stenosis of the SCA (n=1). In the remaining 7 patients, MRI did not detect abnormalities.

Conclusions

TOS can be evaluated by CE-MRA, T2-STIR-SPACE, and VIBE during a single examination, with a reduced contrast material dose. This imaging modality performs well in showing the anatomical structure of the neurovascular bundle and the cause of the compression.

Local Anesthetic Block of the Anterior Scalene Muscle Increases Muscle Height in Patients With Neurogenic Thoracic Outlet Syndrome

BACKGROUND

Local anesthetic (LA) blocks of the anterior scalene muscle are used to predict which patients with neurogenic thoracic outlet syndrome (TOS) may benefit from surgical decompression. The block is thought to work through both analgesic and muscle relaxation effects, but evidence of the latter is lacking. The aim of our study was to assess the effects of LA blocks on anterior scalene muscle anatomy as captured by magnetic resonance imaging (MRI).

METHODS

Over a two-year period, a series of patients with neurogenic TOS underwent MRI-guided anterior scalene blocks with an LA. Patients underwent MRI both before injection and 30 minutes after injection. Anterior scalene muscle heights (measured from the superior border of the first rib to the top of C3 vertebrae) before and after injection were compared for the injected side and the noninjected (control) side, both overall and stratified by subjective patient response to injection.

RESULTS

A total of 54 patients with neurogenic TOS were included. The median age was 39 years (interquartile range, 27-45), 61% were women, and 46% had a history of neck trauma. Forty-five patients (83%) had a favorable response to injection. Overall, there was no significant change in scalene muscle height for either the injected side (preinjection: 90.0 ± 1.2 mm vs. postinjection: 90.7 ± 1.2; P = 0.12) or the control side (preinjection: 89.3 ± 1.4 mm vs. postinjection: 88.9 ± 1.3 mm; P = 0.83). However, when stratified by patient response, those with a positive response had a larger increase in muscle height for the injected side than for the control side (change in baseline: 0.65 ± 0.58 mm vs. -0.53 ± 0.48 mm; P = 0.05). In contrast, nonresponders had no significant change in scalene height for either the injected or control side (change in baseline: 0.59 ± 1.30 mm vs. 0.37 ± 1.07; P = 1.00). Notably, responders had significantly longer anterior scalene muscles at baseline than nonresponders (92.2 ± 1.1 mm vs. 79.5 ± 2.5; P < 0.001).

CONCLUSIONS

LA blocks of the anterior scalene muscle may provide symptomatic relief in patients with neurogenic TOS by increasing muscle height, although the clinical significance of this small change is unclear. Patients who do not have a response to the block tend to have significantly shorter anterior scalene muscle heights than patients who respond, suggesting an anatomic difference in responders versus nonresponders.

Neuromuscular Ultrasound: Clinical Applications and Diagnostic Values

Advances in high-resolution ultrasound have provided clinicians with unique opportunities to study diseases of the peripheral nervous system. Ultrasound complements the clinical and electrophysiology exam by showing the degree of abnormalities in myopathies, as well as spontaneous muscle activities in motor neuron diseases and other disorders. In experienced hands, ultrasound is more sensitive than MRI in detecting peripheral nerve pathologies. It can also guide needle placement for electromyography exam, therapeutic injections, and muscle biopsy. Ultrasound enhances the ability to detect carpal tunnel syndrome and other focal nerve entrapment, as well as pathological nerve enlargements in genetic and acquired neuropathies. Furthermore, ultrasound can potentially be used as a biomarker for muscular dystrophy and spinal muscular atrophy. The combination of electromyography and ultrasound can increase the diagnostic certainty of amyotrophic lateral sclerosis, aid in the localization of brachial plexus or peripheral nerve trauma and allow for surveillance of nerve tumor progression in neurofibromatosis. Potential limitations of ultrasound include an inability to image deeper structures, with lower sensitivities in detecting neuromuscular diseases in young children and those with mitochondrial myopathies, due to subtle changes or early phase of the disease. As well, its utility in detecting critical illness neuromyopathy remains unclear. This review will focus on the clinical applications of neuromuscular ultrasound. The diagnostic values of ultrasound for screening of myopathies, neuropathies, and motor neuron diseases will be presented.

Indications for neuromuscular ultrasound: Expert opinion and review of the literature

Over the last two decades, dozens of applications have emerged for ultrasonography in neuromuscular disorders. We wanted to measure its impact on practice in laboratories where the technique is in frequent use. After identifying experts in neuromuscular ultrasound and electrodiagnosis, we assessed their use of ultrasonography for different indications and their expectations for its future evolution. We then identified the earliest papers to provide convincing evidence of the utility of ultrasound for particular indications and analyzed the relationship of their date of publication with expert usage. We found that experts use ultrasonography often for inflammatory, hereditary, traumatic, compressive and neoplastic neuropathies, and somewhat less often for neuronopathies and myopathies. Usage significantly correlated with the timing of key publications in the field. We review these findings and the extensive evidence supporting the value of neuromuscular ultrasound. Advancement of the field of clinical neurophysiology depends on widespread translation of these findings.

New Diagnostic and Treatment Modalities for Neurogenic Thoracic Outlet Syndrome

Neurogenic thoracic outlet syndrome is a widely recognized, yet controversial, syndrome. The lack of specific objective diagnostic modalities makes diagnosis difficult. This is compounded by a lack of agreed upon definitive criteria to confirm diagnosis. Recent efforts have been made to more clearly define a set of diagnostic criteria that will bring consistency to the diagnosis of neurogenic thoracic syndrome. Additionally, advancements have been made in the quality and techniques of various imaging modalities that may aid in providing more accurate diagnoses. Surgical decompression remains the mainstay of operative treatment; and minimally invasive techniques are currently in development to further minimize the risks of this procedure. Medical management continues to be refined to provide non-operative treatment modalities for certain patients, as well. The aim of the present work is to review these updates in the diagnosis and treatment of neurogenic thoracic outlet syndrome.