Role of magnetic resonance imaging in entrapment and compressive neuropathy--what, where, and how to see the peripheral nerves on the musculoskeletal magnetic resonance image: part 2. Upper extremity

Technical Update on MR Neurography

Imaging evaluation of peripheral nerves (PNs) is challenging. Magnetic resonance imaging (MRI) and ultrasonography are the modalities of choice in the imaging assessment of PNs. Both conventional MRI pulse sequences and advanced techniques have important roles. Routine MR sequences are the workhorse, with the main goal to provide superb anatomical definition and identify focal or diffuse nerve T2 signal abnormalities. Selective techniques, such as three-dimensional (3D) cranial nerve imaging (CRANI) or 3D NerveVIEW, allow for a more detailed evaluation of normal and pathologic states. These conventional pulse sequences have a limited role in the comprehensive assessment of pathophysiologic and ultrastructural abnormalities of PNs. Advanced functional MR neurography sequences, such as diffusion tensor imaging tractography or T2 mapping, provide useful and robust quantitative parameters that can be useful in the assessment of PNs on a microscopic level. This article offers an overview of various technical parameters, pulse sequences, and protocols available in the imaging of PNs and provides tips on avoiding potential pitfalls.

Imaging of Elbow Injuries

Familiarity with throwing mechanics during elbow range of motion allows accurate diagnosis of sports-related elbow injuries, which occur in predictable patterns. In addition, repetitive stress-related injuries are often clinically apparent; however, imaging plays an important role in determining severity as well as associated injuries that may affect clinical management. A detailed understanding of elbow imaging regarding anatomy and mechanism of injury results in prompt and precise treatment.

Compression neuropathies of the forearm: anatomy, clinical features and management

The upper limb consists of four major parts: a girdle formed by the clavicle and scapula, the arm, the forearm and the hand. Peripheral nerve lesions of the upper limb are divided into lesions of the brachial plexus or the nerves arising from it. Lesions of the nerves arising from the brachial plexus are further divided into upper (proximal) or lower (distal) lesions based on their location. Peripheral nerves in the forearm can be compressed in various locations and by a wide range of pathologies. A thorough understanding of the anatomy and clinical presentations of these compression neuropathies can lead to prompt diagnosis and management, preventing possible permanent damage. This article discusses the aetiology, anatomy, clinical presentation and surgical management of compressive neuropathies of the upper limb.

Diagnosis and treatment of nerve injury following venipuncture - A report of two cases

BACKGROUND

Venipuncture is one of the one of the most commonly performed, minimally-invasive procedures; however, it may lead to peripheral nerve injury. Here, we describe the diagnosis, treatment, and prognosis of two self-reported cases of nerve injury during venipuncture with the aim of drawing attention to possible needle-related nerve injuries.

CASE

Two anesthesiologists in our hospital experienced an injury of the lateral antebrachial cutaneous branch of the musculocutaneous nerve during venipuncture. Immediately, they underwent ultrasound examinations and nerve blocks with oral medication, resulting in full recovery.

CONCLUSIONS

Ultrasonography is important for the early and confirmative diagnosis of a nerve injury during venipuncture, and for immediate treatment with a nerve block. Moreover, it is imperative for both the practitioner and the patient to be aware of the possible complication of nerve injury after venipuncture.

Primary elbow osteoarthritis presenting as ulnar nerve palsy with claw hand

A 59-year-old woman was referred with weakness, paraesthesia, numbness and clawing of the little and ring fingers for the last 2 years. MRI of the cervical spine was normal and nerve conduction velocity revealed abnormality of the ulnar nerve. Ultrasound and MRI showed medial osteophytes and effusion of the elbow joint with stretched and thinned ulnar nerve in the cubital tunnel. The patient underwent release and anterior transposition of the ulnar nerve with significant relief of symptoms.

T2 mapping of the median nerve in patients with carpal tunnel syndrome and healthy volunteers

INTRODUCTION

We investigated the changes in MRI T2 mapping values in subjects with carpal tunnel syndrome (CTS) compared to healthy controls.

METHODS

We enrolled 71 patients with CTS and 26 healthy controls. Median nerve T2 values were measured at the distal carpal tunnel, hamate bone, proximal carpal tunnel, and forearm levels. These were compared between patients and controls and correlated with median nerve cross-sectional area (CSA) and nerve conduction measurements.

RESULTS

The mean T2 values at the proximal carpal tunnel levels were higher in the CTS group (56.7 ms) than in the control group (51.2 ms, P = .02) and also were higher than at the distal carpal tunnel (51.0 ms, P < .001) and forearm levels (47.6 ms, P < .001). T2 values were not significantly associated with CSA or nerve conduction measurements.

DISCUSSION

T2 mapping of the carpal tunnel provides qualitative information on median nerve pathology but does not reflect CTS severity.

Etiology Diagnosis and Management of Radial Nerve Entrapment

Context

The anatomy of the radial nerve is prone to entrapment, each with different symptomology. Compression of entrapment of the radial nerve can occur near the radiocapitellar joint, the spiral groove, the arcade of Frohse, the tendon of the extensor carpi radialis brevis (ECRB), and at the radial tunnel. Those who require repetitive motions are at increased risk of peripheral neuropathy syndromes, including repetitive pronation and supination, trauma, or systemic disease; however, t the influence of all risk factors is not well understood. Depending on the location of entrapment, radial nerve entrapment syndrome presents different symptoms. It may include both a motor component and a sensory component. The motor component includes a dropped arm, and the sensory component can include pain and paresthesia in the distribution of the radial nerve that resolves with rest and exacerbates by repetitive pronation and supination.

Evidence Acquisition

Diagnostic evaluation for radial nerve entrapment, apart from clinical symptoms and physical exam, includes electromyography, nerve conduction studies, ultrasonography, and magnetic resonance imaging. Conservative management for radial nerve entrapment includes oral anti-inflammatory medications, activity modification, and splinting. Some recently performed studies mentioned promising minimally invasive techniques, including corticosteroid injections, peripheral nerve stimulation, and pulsed radiofrequency.

Results

When minimally invasive techniques fail, open or endoscopic surgery can be performed to release the nerve

Conclusions

Endoscopic surgery has the benefit of decreasing incision size and reducing time to functional recovery.

An Update on Treatment Modalities for Ulnar Nerve Entrapment: A Literature Review

CONTEXT

Ulnar nerve entrapment is a relatively common entrapment syndrome second only in prevalence to carpal tunnel syndrome. The potential anatomic locations for entrapment include the brachial plexus, cubital tunnel, and Guyon's canal. Ulnar nerve entrapment is more so prevalent in pregnancy, diabetes, rheumatoid arthritis, and patients with occupations involving periods of prolonged elbow flexion and/or wrist dorsiflexion. Cyclists are particularly at risk of Guyon's canal neuropathy. Patients typically present with sensory deficits of the palmar aspect of the fourth and fifth digits, followed by motor symptoms, including decreased pinch strength and difficulty fastening shirt buttons or opening bottles.

EVIDENCE ACQUISITION

Literature searches were performed using the below MeSH Terms using Mendeley version 1.19.4. Search fields were varied until further searches revealed no new articles. All articles were screened by title and abstract. Decision was made to include an article based on its relevance and the list of final articles was approved three of the authors. This included reading the entirety of the artice. Any question regarding the inclusion of an article was discussed by all authors until an agreement was reached.

RESULTS

X-ray and CT play a role in diagnosis when a bony injury is thought to be related to the pathogenesis (i.e., fracture of the hook of the hamate.) MRI plays a role where soft tissue is thought to be related to the pathogenesis (i.e., tumor or swelling.) Electromyography and nerve conduction also play a role in diagnosis. Medical management, in conjunction with physical therapy, shows limited promise. However, minimally invasive techniques, including peripheral percutaneous electrode placement and ultrasound-guided electrode placement, have all been recently studied and show great promise. When these techniques fail, clinicians should resort to decompression, which can be done endoscopically or through an open incision. Endoscopic ulnar decompression shows great promise as a surgical option with minimal incisions.

CONCLUSIONS

Clinical diagnosis of ulnar nerve entrapment can often be delayed and requires the suspicion as well as a thorough neurological exam. Early recognition and diagnois are important for early institution of treatment. A wide array of diagnostic imaging can be useful in ruling out bony, soft tissue, or vascular etiologies, respectively. However, clinicians should resort to electrodiagnostic testing when a definitive diagnois is needed. Many new minimally invasive techniques are in the literature and show great promise; however, further large scale trials are needed to validate these techniques. Surgical options remains as a gold standard when adequate symptom relief is not achieved through minimally invasive means.

Comparison of MR findings of acute traumatic peripheral nerve injury and acute compressive neuropathy in a rat model

Purpose

The treatment strategy is different for acute traumatic peripheral nerve injury and acute compressive neuropathy. This study aimed to compare magnetic resonance imaging (MRI) features of acute traumatic peripheral nerve injury and acute compressive neuropathy in a rat model.

Materials and methods

Twenty female Sprague-Dawley rats were divided into two groups. In the crush injury group (n = 10), the unilateral sciatic nerve was crushed using forceps to represent acute traumatic peripheral nerve injury. In the compression injury group (n = 10), the unilateral sciatic nerve was ligated using silk to represent acute compressive neuropathy. The MRI of eight rats from each group were acquired on postoperative days 3 and 10. Fat-suppressed T2-weighted images were acquired. Changes in the injured nerve were divided into three grades. A Fisher’s exact test was used to compare the changes in the nerves of the two groups. Histological staining and a western blot analysis were performed on one rat in each group on day 3. Neurofilament, myelin basic protein (MBP), and p75^NTR staining were performed. Expression of neurofilament, MBP, p75^NTR, and c-jun was evaluated by western blot analysis.

Results

MR neurography revealed substantial nerve changes in the compression injury group compared with the crush injury group at two-time points (p = 0.001 on day 3, p = 0.026 on day 10). The histopathological analysis indicated the destruction of the axon and myelin, mainly at the injury site and the distal portion of the injury in the crush injury group. It was prominent in the proximal portion, the injury site, and the distal portion of the injury in the compression injury group. The degree of axonal and myelin destruction was more pronounced in the compression injury group than in the crush injury group.

Conclusion

MR neurography showed prominent and long-segmental changes associated with the injured nerve in acute compressive neuropathy compared with acute traumatic peripheral nerve injury.

Repetitive Strain Injuries of the Upper Extremity: Imaging of Tendon Pathology and Compressive Neuropathies

Repetitive strain injuries (RSIs) encompass a broad clinicopathologic spectrum which includes discrete patterns of tissue injury involving tendons, bursae and nerves although an element of subjective symptomatology may be contributory. Upper extremity RSIs include De Quervain's tenosynovitis, intersection syndromes, epicondylitis, ulnar, and median neuritis as well as other compressive neuropathies. It is estimated that RSIs cost the US economy over $60 billion annually and while detailed clinical examination remains the diagnostic mainstay, imaging can aid in diagnosis, guide management and reduce costs.

Ultrasound imaging of nerves in the neck: Correlation with MRI, EMG, and clinical findings

Objective

We evaluated the performance of ultrasound in the detection of neuropathy of the suprascapular nerve (SSN), long thoracic nerve (LTN), spinal accessory nerve (SAN), and phrenic nerve and compared this performance with MRI.

Methods

A retrospective review of 56 patients who had undergone ultrasound imaging of the SSN, LTN, SAN, and phrenic nerve was performed. Diagnoses made by ultrasound, MRI, EMG reports, and clinical and operative notes were recorded.

Results

Ultrasound was successful in visualizing nerves in the neck in the overwhelming majority of cases. Sonographic findings were typically in agreement with MRI and clinical findings.

Conclusion

Ultrasound is effective in the visualization and diagnostic evaluation of the SSN, LTN, SAN, and phrenic nerve.

Classification of evidence

This study provides Class IV evidence that ultrasound can effectively visualize and diagnose neuropathy of the SSN, LTN, SAN, and phrenic nerve in the neck.

Shear-wave elastography: a new potential method to diagnose ulnar neuropathy at the elbow

Objectives

The primary aim of this study was to verify if shear-wave elastography (SWE) can be used to diagnose ulnar neuropathy at the elbow (UNE). The secondary objective was to compare the cross-sectional areas (CSA) of the ulnar nerve in the cubital tunnel and to determine a cut-off value for this parameter accurately identifying persons with UNE.

Methods

The study included 34 patients with UNE (mean age, 59.35 years) and 38 healthy controls (mean age, 57.42 years). Each participant was subjected to SWE of the ulnar nerve at three levels: in the cubital tunnel (CT) and at the distal arm (DA) and mid-arm (MA). The CSA of the ulnar nerve in the cubital tunnel was estimated by means of ultrasonographic imaging.

Results

Patients with UNE presented with significantly greater ulnar nerve stiffness in the cubital tunnel than the controls (mean, 96.38 kPa vs. 33.08 kPa, p < 0.001). Ulnar nerve stiffness of 61 kPa, CT to DA stiffness ratio equal 1.68, and CT to MA stiffness ratio of 1.75 provided 100% specificity, sensitivity, positive and negative predictive value in the detection of UNE. Mean CSA of the ulnar nerve in the cubital tunnel turned out to be significantly larger in patients with UNE than in healthy controls (p < 0.001). A weak positive correlation was found in the UNE group between the ulnar nerve CSA and stiffness (R = 0.31, p = 0.008).

Conclusions

SWE seems to be a promising, reliable and simple quantitative adjunct test to support the diagnosis of UNE.

Key Points

• SWE enables reliable detection of cubital tunnel syndrome

• Significant increase of entrapped ulnar nerve stiffness is observed in UNE

• SWE is a perspective screening tool for early detection of compressive neuropathies

Evaluation of median nerve T2 signal changes in patients with surgically treated carpal tunnel syndrome

OBJECTIVE

To determine the accuracy of median nerve T2 evaluation and its relation with Boston Questionnaire (BQ) and nerve conduction studies (NCSs) in pre-operative and post-operative carpal tunnel syndrome (CTS) patients in comparison with healthy volunteers.

METHODS

Twenty-three CTS patients and 24 healthy volunteers underwent NCSs, median nerve T2 evaluation and self-administered BQ. Pre-operative and 1st year post-operative median nerve T2 values and cross-sectional areas (CSAs) were compared both within pre-operative and post-operative CTS groups, and with healthy volunteers. The relationship between MRI findings and BQ and NCSs was analyzed. The ROC curve analysis was used for determining the accuracy.

RESULTS

The comparison of pre-operative and post-operative T2 values and CSAs revealed statistically significant improvements in the post-operative patient group (p<0.001 for all parameters). There were positive correlations between T2 values at all levels and BQ values, and positive and negative correlations were also found regarding T2 values and NCS findings in CTS patients. The receiver operating characteristic curve analysis for defined cut-off levels of median nerve T2 values in hands with severe CTS yielded excellent accuracy at all levels. However, this accuracy could not be demonstrated in hands with mild CTS.

CONCLUSION

This study is the first to analyze T2 values in both pre-operative and post-operative CTS patients. The presence of increased T2 values in CTS patients compared to controls and excellent accuracy in hands with severe CTS indicates T2 signal changes related to CTS pathophysiology and possible utilization of T2 signal evaluation in hands with severe CTS.

Beyond the Cuff: MR Imaging of Labroligamentous Injuries in the Athletic Shoulder

Shoulder disease is common in the athletic population and may arise as a consequence of a single traumatic episode or multiple repeated events. Associated labroligamentous injuries can result in substantial disability. Specific athletic and occupational activities result in predictable injury patterns. Imaging in general and magnetic resonance (MR) imaging, in particular, are vital in establishing the correct diagnosis and excluding common mimicking conditions, to ensure timely and appropriate management. In this review, the utility of MR imaging and MR arthrography will be explored in evaluation of shoulder disease, taking into account normal variants of the labroligamentous complex. Subsequently, broad categories of labral lesions and instability, external and internal impingement, as well as nerve entrapment syndromes, will be discussed, while emphasizing their imaging findings in the clinical context and illustrating key features. More recent concepts of internal impingement and secondary subacromial impingement will also be clarified.

Entrapment and traumatic neuropathies of the elbow and hand: An imaging approach

Ultrasound and magnetic resonance imaging currently offer a detailed analysis of the peripheral nerves. Compressive and traumatic nerve injuries are the two main indications for imaging investigation of nerves with several publications describing the indications, technique and diagnostic capabilities of imaging signs. Investigation of entrapment neuropathies has three main goals, which are to confirm neuronal distress, search for the cause of nerve compression and exclude a differential diagnosis on the entire nerve. For traumatic nerve injuries, imaging, predominantly ultrasound, occasionally provides essential information for management including the type of nerve lesion, its exact site and local extension.

Neurogenic thoracic outlet syndrome due to subclavius posticus muscle with dynamic brachial plexus compression: a case report

Background

Neurogenic thoracic outlet syndrome is an underestimated cause of brachial weakness and pain. The subclavius posticus muscle (SPM) is an aberrant muscle originating from the medial aspect of the first rib reaching to superior border of the scapula, which may cause, depending on its activation, dynamic compression of the brachial plexus.

Case presentation

In the present study, we report about a 32-year-old male caucasian patient with weakness in radial deviation of his left hand. An isolated macrodactyly of his left middle finger had been operated twice. Electroneurography showed a carpal-tunnel-syndrome (CTS) on the left side. MRI of the brachial plexus revealed an additional muscle in the costoclavicular space, identified as SPM. To our knowledge, this is the second case report of a neurogenic thoracic outlet syndrome due to SPM, and the first case described with isolated macrodactyly and CTS in the same patient.

Conclusion

If complaints about hand weakness are only reported in cases of distinct hand positions, a dynamic compression of the brachial plexus by SPM may be the cause. A neurogenic thoracic outlet syndrome may facilitate the development of CTS.

Cross-sectional sonographic assessment of the posterior interosseous nerve

PURPOSE

Cross-sectional sonographic measurements are considered first-line confirmatory tests in diagnosing peripheral nerve entrapment syndromes. Our aim is to establish normal values of cross-sectional area of the posterior interosseous nerve (PIN) at the arcade of Frohse, the most common site of compression of this nerve.

METHODS

The PIN was identified with ultrasound on 50 healthy adults and 30 cadavers. Measurements of the cross-sectional area (CSA), antero-posterior (AP) and lateral (L) distances were taken immediately proximal and distal to the arcade of Frohse.

RESULTS

The mean AP and L distances of the PIN proximal to the arcade of Frohse were 0.111 cm (0 ± 0.021) and 0.266 cm (±0.058), respectively, while the mean AP and L distances of the PIN distal to the arcade of Frohse were 0.085 cm (±0.019) and 0.343 cm (±0.057), respectively. P squared testing showed a statistically significant difference between the AP and lateral distances of the PIN when comparing proximal and distal to the arcade (p ≤ 0.001). However, the mean CSA of the PIN measured immediately proximal to the arcade of Frohse was 0.022 cm(2) (±0.005); immediately distal to the arcade of Frohse, it was 0.023 cm(2) (±0.004). t test showed no statistical difference between the two regions (p = 0.11).

CONCLUSIONS

Our study has provided reference values for the PIN in healthy individuals at the arcade of Frohse. Although, there is a flattening of the nerve as it enters the supinator muscle, this should not be mistaken for nerve entrapment as the size of the nerve remains consistent.

Nerve entrapment: update

LEARNING OBJECTIVES

After reading this article, the participant should be able to: 1. Understand the pathophysiology of chronic nerve compression. 2. Describe the evaluation of a patient presenting with compression neuropathy. 3. Discuss the current controversies in the management of compression neuropathies. 4. Describe the treatment of common compression neuropathies, including carpal and cubital tunnel syndromes.

SUMMARY

Nerve entrapment syndromes are common in the general population, and are managed by a wide variety of medical and surgical specialists. A thorough understanding of the pathophysiology of nerve compression and appropriate clinical workup are critical in the overall management of these conditions. There remain several topics of controversy regarding the surgical management of nerve entrapment syndromes, including multiple points of nerve compression, carpal tunnel release under local anesthesia, open versus endoscopic decompression surgery, the "best" operation for primary cubital tunnel surgery, and revision decompression surgery. This article attempts to provide a concise summary of the advances in the basic and clinical science of peripheral nerve entrapment.

Peripheral nerve injuries due to osteochondromas: analysis of 20 cases and review of the literature

Object

Nerve compressions due to osteochondromas are extremely rare. The aim of this retrospective study was to investigate the mechanisms, diagnostic evaluations, and treatment of nerve lesions due to osteochondromas, and to review the literature.

Methods

The authors retrospectively reviewed their clinic data archive from 1998 through 2008, and 20 patients who were operated on due to peripheral nerve injuries caused by osseous growth were enrolled in the study. Patients' age, duration of symptoms, localizations, intraoperative findings, and modified British Medical Research Council (MRC) and electromyography data obtained from hospital records were evaluated. The literature on this topic available in PubMed was also reviewed. All 20 patients underwent surgery, which consisted of tumor excision performed by orthopedic surgeons and nerve decompression performed by neurosurgeons.

Results

There were 17 men and 3 women included in the study, with a mean age of 21 years (range 18–25 years). Three patients had multiple hereditary exostoses, and 17 had a solitary exostosis. All of the patients underwent en bloc resection. The most common lesion site was the distal femur (45%). The peroneal and posterior tibial nerves were the structures that were affected the most frequently. The mean follow-up was 3.9 years (range 2–7 years). After the surgery, all patients (100%) experienced good sensory recovery (modified MRC Grade S4 or S5).

Conclusions

To the authors' knowledge, no large series have reported peripheral nerve compression due to exostoses. The authors have several recommendations as a result of their findings. First, all patients with peripheral nerve compression due to an osteochondroma should undergo surgery. Second, preoperative electromyographic examinations and radiographic evaluation, consisting of MRI and CT to provide optimal information about the lesion, are crucially important. Third, immediate treatment is mandatory to regain the best possible recovery. And fourth, performing nerve decompression first and en bloc resection of osteochondroma consecutively in a multidisciplinary fashion is strongly recommended to avoid peripheral nerve injury.

Can testing of six individual muscles represent a screening approach to upper limb neuropathic conditions?

BACKGROUND

It has previously been demonstrated that an extensive upper limb neurological examination of individual muscle function, sensation in homonymous innervated territories, and nerve trunk allodynia is reliable and that the outcome reflects symptoms. Since this approach may appear complicated and time consuming, this study deals with the value of an examination limited to manual testing of only six muscles.

METHODS

Two examiners blinded to symptom status performed manual muscle testing of six muscles in 82 upper limbs with or without pain, weakness, and/or numbness/tingling. The six muscles represent three antagonist pairs (pectoralis major/posterior deltoid, biceps/triceps, and radial flexor of wrist/short radial extensor of wrist). The inter-rater reliability of detecting muscular weaknesses and the relation of weakness to the mentioned symptoms were analysed by kappa-statistics.

RESULTS

The two examiners recognized weaknesses in 48 and 55 limbs, respectively, with moderate agreement (median kappa = 0.58). Out of these, 35 and 32 limbs, respectively, were symptomatic. There was good correlation between findings and symptoms for one examiner (kappa = 0.61) and fair correlation for the other one (kappa = 0.33). Both reached high sensitivity (0.92, 0.84) but less satisfactory specificity (0.70, 0.50). Weaknesses agreed upon by the two examiners correlated moderately with symptoms (kappa = 0.57).

CONCLUSIONS

Weakness in one or more muscles was present in almost all symptomatic limbs but in many non-symptomatic limbs as well. Manual testing of six muscles may represent a useful screening approach to upper limb neuropathic conditions, but a confirmative diagnosis requires further assessment.

Functional restoration of diaphragmatic paralysis: an evaluation of phrenic nerve reconstruction

BACKGROUND

Unilateral diaphragmatic paralysis causes respiratory deficits and can occur after iatrogenic or traumatic phrenic nerve injury in the neck or chest. Patients are evaluated using spirometry and imaging studies; however, phrenic nerve conduction studies and electromyography are not widely available or considered; thus, the degree of dysfunction is often unknown. Treatment has been limited to diaphragmatic plication. Phrenic nerve operations to restore diaphragmatic function may broaden therapeutic options.

METHODS

An interventional study of 92 patients with symptomatic diaphragmatic paralysis assigned 68 (based on their clinical condition) to phrenic nerve surgical intervention (PS), 24 to nonsurgical (NS) care, and evaluated a third group of 68 patients (derived from literature review) treated with diaphragmatic plication (DP). Variables for assessment included spirometry, the Short-Form 36-Item survey, electrodiagnostics, and complications.

RESULTS

In the PS group, there was an average 13% improvement in forced expiratory volume in 1 second (p < 0.0001) and 14% improvement in forced vital capacity (p < 0.0001), and there was corresponding 17% (p < 0.0001) and 16% (p < 0.0001) improvement in the DP cohort. In the PS and DP groups, the average postoperative values were 71% for forced expiratory volume in 1 second and 73% for forced vital capacity. The PS group demonstrated an average 28% (p < 0.01) improvement in Short-Form 36-Item survey reporting. Electrodiagnostic testing in the PS group revealed a mean 69% (p < 0.05) improvement in conduction latency and a 37% (p < 0.0001) increase in motor amplitude. In the NS group, there was no significant change in Short-Form 36-Item survey or spirometry values.

CONCLUSIONS

Phrenic nerve operations for functional restoration of the paralyzed diaphragm should be part of the standard treatment algorithm in the management of symptomatic patients with this condition. Assessment of neuromuscular dysfunction can aid in determining the most effective therapy.

High-resolution sonography detects extraforaminal nerve pathology in patients initially diagnosed with cervical disc disease: a case series

In patients presenting with neck and upper limb complaints, MRI changes suggestive of cervical disc disease do not exclude concomitant extraforaminal pathology, as shown in the series of three cases presented here. High-resolution ultrasound of the brachial plexus and peripheral nerves may be useful in identifying an extraforaminal pathology when (1) symptoms and signs are disproportionate to MRI findings of cervical disc disease; (2) there is obvious discordance between MRI and nerve conduction findings; (3) an entrapment neuropathy is suspected but the site of nerve lesion is unidentifiable on the basis of available investigations and clinical findings.

Entrapment neuropathies in the upper and lower limbs: anatomy and MRI features

Peripheral nerve entrapment occurs at specific anatomic locations. Familiarity with the anatomy and the magnetic resonance imaging (MRI) features of nerve entrapment syndromes is important for accurate diagnosis and early treatment of entrapment neuropathies. The purpose of this paper is to illustrate the normal anatomy of peripheral nerves in the upper and lower limbs and to review the MRI features of common disorders affecting the peripheral nerves, both compressive/entrapment and noncompressive, involving the suprascapular nerve, the axillary nerve, the radial nerve, the ulnar nerve, and the median verve in the upper limb and the sciatic nerve, the common peroneal nerve, the tibial nerve, and the interdigital nerves in the lower limb.

Peripheral nerve surgery: the role of high-resolution MR neurography

High-resolution MRN is becoming increasingly available due to recent technical advancements, including higher magnetic field strengths (eg, 3T), 3D image acquisition, evolution of novel fat-suppression methods, and improved coil design. This review describes the MRN techniques for obtaining high-quality images of the peripheral nerves and their small branches and imaging findings in normal as well as injured nerves with relevant intraoperative correlations. Various microsurgical techniques in peripheral nerves, such as neurolysis, nerve repairs by using nerve grafts, and conduits are discussed, and MRN findings of surgically treated nerves are demonstrated.

High resolution imaging of tunnels by magnetic resonance neurography

Peripheral nerves often traverse confined fibro-osseous and fibro-muscular tunnels in the extremities, where they are particularly vulnerable to entrapment and compressive neuropathy. This gives rise to various tunnel syndromes, characterized by distinct patterns of muscular weakness and sensory deficits. This article focuses on several upper and lower extremity tunnels, in which direct visualization of the normal and abnormal nerve in question is possible with high resolution 3T MR neurography (MRN). MRN can also serve as a useful adjunct to clinical and electrophysiologic exams by discriminating adhesive lesions (perineural scar) from compressive lesions (such as tumor, ganglion, hypertrophic callous, or anomalous muscles) responsible for symptoms, thereby guiding appropriate treatment.

MR imaging of the brachial plexus: comparison between 1.5-T and 3-T MR imaging: preliminary experience

OBJECTIVE

To compare 1.5-T and 3-T magnetic resonance (MR) imaging of the brachial plexus.

MATERIALS AND METHODS

Institutional review board approval and informed consent were obtained from 30 healthy volunteers and 30 consecutive patients with brachial plexus disturbances. MR was prospectively performed with comparable sequence parameters and coils with a 1.5-T and a 3-T system. Imaging protocols at both field strengths included T1-weighted turbo spin-echo (tSE) sequences and T2-weighed turbo spin-echo (tSE) sequences with fat saturation. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) between muscle and nerve were calculated for both field strengths. The visibility of brachial plexus nerve at various anatomic levels (roots, interscalene area, costoclavicular space, and axillary level) was analyzed with a four-point grading scale by two radiologists. MR imaging diagnoses and pathological findings were also compared qualitatively.

RESULTS

SNR and CNRs were significantly higher on 3-T MR images than on 1.5-T MR images (Friedman test) for all sequences. Nerve visibility was significantly better on 3-T MR images than on 1.5-T MR images (paired sign test). Pathological findings (n = 30/30) were seen equally well with both field strengths. MR imaging diagnoses did not differ for the 1.5- and 3-T protocols.

CONCLUSIONS

High-quality MR images of the brachial plexus can be obtained with 3-T MR imaging by using sequences similar to those used at 1.5-T MR imaging. In patients and healthy volunteers, the visibility of nerve trunks and cords at 3-T MR imaging appears to be superior to that at 1.5-T MR imaging.

Brachial plexus assessment with three-dimensional isotropic resolution fast spin echo MRI: comparison with conventional MRI at 3.0 T

OBJECTIVE

The purpose of our study was to determine whether a three-dimensional (3D) isotropic resolution fast spin echo sequence (FSE-cube) has similar image quality and diagnostic performance to a routine MRI protocol for brachial plexus evaluation in volunteers and symptomatic patients at 3.0 T. Institutional review board approval and written informed consent were guaranteed.

METHODS

In this prospective study FSE-cube was added to the standard brachial plexus examination protocol in eight patients (mean age, 50.2 years) with brachial plexus pathologies and in six volunteers (mean age, 54 years). Nerve visibility, tissue contrast, edge sharpness, image blurring, motion artefact and acquisition time were calculated for FSE-cube sequences and for the standard protocol on a standardised five-point scale. The visibility of brachial plexus nerve and surrounding tissues at four levels (roots, interscalene area, costoclavicular space and axillary level) was assessed.

RESULTS

Image quality and nerve visibility did not significantly differ between FSE-cube and the standard protocol (p>0.05). Acquisition time was statistically and clinically significantly shorter with FSE-cube (p<0.05). Pathological findings were seen equally well with FSE-cube and the standard protocol.

CONCLUSION

3D FSE-cube provided similar image quality in a shorter acquisition time and enabled excellent visualisation of brachial plexus anatomy and pathology in any orientation, regardless of the original scanning plane.

What's new in the diagnosis and treatment of peripheral nerve entrapment neuropathies

Entrapment neuropathies can be common conditions with the potential to cause significant disability. Correct diagnosis is essential for proper management. This article is a review of recent developments related to diagnosis and treatment of various common and uncommon nerve entrapment disorders. When combined with classical peripheral nerve examination techniques, innovations in imaging modalities have led to more reliable diagnoses. Moreover, innovations in conservative and surgical techniques have been controversial as to their effects on patient outcome, but randomized controlled trials have provided important information regarding common operative techniques. Treatment strategies for painful peripheral neuropathies are also reviewed.

[Traumatic cord and nerve root injuries: imaging features at the acute and chronic phases]

Cord injuries are frequent and severe lesions resulting in significant disability, most frequently in younger subjects. The area of cord injured results in clinical syndromes (Brown-Sequard, motor and/or sensory deficit...). Cord and rootlet injuries are best depicted on MRI. Diffusion tensor imaging with tractography enables depiction of the most severe cord lesions and some prediction of tissue viability which may provide an idea of the potential functional prognosis and patient recovery. MRI is optimal to demonstrate areas of cord hemorrhage or compression, partial or complete cord transsection, nerve root avulsion...

High-resolution MR neurography of diffuse peripheral nerve lesions

High-resolution MR imaging of peripheral nerves is becoming more common and practical with the increasing availability of 3T magnets. There are multiple reports of MR imaging of peripheral nerves in compression and entrapment neuropathies. However, there is a relative paucity of literature on MRN appearance of diffuse peripheral nerve lesions. We attempted to highlight the salient imaging features of myriad diffuse peripheral nerve disorders and imaging techniques for MRN. Using clinical and pathologically proved relevant examples, we present the MRN appearance of various types of diffuse peripheral nerve lesions, such as traumatic, inflammatory, infectious, hereditary, radiation-induced, neoplastic, and tumor variants.

Compressive neuropathies of the upper extremity: update on pathophysiology, classification, and electrodiagnostic findings

Clinical examination and electrodiagnostic studies remain the gold standard for diagnosis of nerve injuries. Diagnosis of chronic nerve compression (CNC) injuries can be difficult in patients with confounding factors such as diabetes. The treatment of nerve entrapment ranges from medical to surgical management, depending on the nerve involved and on the severity and duration of compression. Considerable insights have been made at the molecular level, differentiating between nerve crush injuries and CNC injuries. Although the myelin changes after CNC injury were previously thought to be a mild form of Wallerian degeneration, recent evidence points to a distinct pathophysiology involving Schwann cell mechanosensitivity. Future areas of research include Schwann cell transplantation in the treatment regimen, the correlation between demyelination and the onset of pain, and the role of Schwann cell integrins in transducing the mechanical forces involved in nerve compression injuries to Schwann cells.