Intra- and internerve cross-sectional area variability: new ultrasound measures

High-resolution nerve ultrasound and corneal confocal microscopy in taxane-induced polyneuropathy

BACKGROUND AND PURPOSE

The role of high-resolution nerve ultrasound (HRUS) and corneal confocal microscopy (CCM) in the early detection of taxane-induced polyneuropathy (TIPN) is unclear. The present prospective longitudinal controlled observational pilot study estimates the role of HRUS and CCM in the early diagnosis of TIPN in breast cancer patients.

METHODS

Fifteen breast cancer patients receiving paclitaxel and 15 healthy age matched controls were included. Visits before and 3 weeks, 8 weeks and 6 months after treatment included clinical examination, the total neuropathy score, nerve conduction studies (NCS), monocular CCM including corneal nerve fibre length, density and branching and HRUS of bilateral median, ulnar, radial, tibial, peroneal and sural nerves. Patients were compared between different visits and to healthy controls.

RESULTS

Total neuropathy score increased from 2.2 at baseline to 5.8 (p < 0.001) at week 8. NCS showed a decreased sensory amplitude in the sural, radial, ulnar and median nerve after 6 months (p < 0.001). HRUS revealed a significant increase of cross-sectional area in the sural nerve (p = 0.004), the median nerve (p = 0.003) at the carpal tunnel and the ulnar nerve in the forearm (p = 0.006) after 6 months. CCM showed no changes at different visits.

CONCLUSIONS

Corneal confocal microscopy and HRUS do not detect early signs of TIPN during the paclitaxel treatment period. HRUS and NCS might detect congruent signs of an axonal, predominantly sensory polyneuropathy after 6 months. The clinical examination remains the most sensitive tool in the early detection of TIPN in breast cancer patients.

Nerve enlargement differs among chronic inflammatory demyelinating polyradiculoneuropathy subtypes and multifocal motor neuropathy

Objective

We aimed to evaluate differences in ultrasonographic nerve enlargement sites among typical chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), distal CIDP, multifocal CIDP and multifocal motor neuropathy (MMN) in a Japanese population.

Methods

We retrospectively reviewed medical records and selected 39 patients (14 with typical CIDP, 7 with multifocal CIDP, 4 with distal CIDP, and 14 with MMN) who underwent ultrasonography. Median and ulnar nerve cross-sectional areas (CSAs) were measured at the wrist, forearm, elbow, and upper arm. CSA ratios for each nerve were calculated as: wrist-to-forearm index (WFI) = wrist CSA/forearm CSA; elbow-to-upper arm index (EUI) = elbow CSA/upper arm CSA; and intranerve CSA variability (INCV) = maximal CSA/minimal CSA.

Results

Significant differences were observed among typical CIDP, multifocal CIDP, distal CIDP, and MMN in CSA at the forearm and upper arm in the median nerves (p < 0.05). Patients with multifocal CIDP had lower WFI and EUI and higher INCV than the other groups (p < 0.05).

Conclusions

Regardless of the untreated period, compared with other CIDP subtypes and MMN, multifocal CIDP showed a focal and marked nerve enlargement in the Japanese population.

Significance

Differences in nerve enlargement site may be an underlying feature of multifocal CIDP.

Nerve ultrasound for the diagnosis and follow-up of peripheral neuropathies

PURPOSE OF REVIEW

The purpose if this review is to provide an overview of the available data on the use of nerve ultrasound for the diagnosis and follow-up of peripheral neuropathies.

RECENT FINDINGS

During the last decade, nerve ultrasound has been established as a complementary tool for the evaluation of morphological changes mostly for immune-mediated polyneuropathies. Through the development of ultrasound protocols for evaluation of disease-specific sites, nerve ultrasound has proven to be a practical, widely available, reproducible diagnostic tool with no relevant contraindications.

SUMMARY

Cross-sectional area, echogenicity, morphology of the individual nerve fascicles, thickness of the epineurium, vascularization and mobility of the nerve are the main parameters evaluated with nerve ultrasound in polyneuropathies. Patients with typical chronic inflammatory demyelinating polyneuropathy show multifocal nerve enlargements easily visible on the upper extremities and the brachial plexus, whereas its variants show focal nerve enlargements. On the other hand, axonal neuropathies including diabetic neuropathy present with isolated nerve enlargement mostly in compression sites.

Nerve ultrasound reference values in children and adolescents: Echogenicity and influence of anthropometric factors including hand volume

Background

Nerve cross-sectional area (CSA) reference values in high-resolution ultrasound for children and adolescents are influenced by demographic and anthropometric factors such as age, height and weight.

Objectives

The influence of hand volume as an additional morphometric factor was evaluated and nerve echogenicity was analyzed in a prospective cross-sectional study.

Methods

CSA were measured in 30 healthy children and adolescents from 2 to 17 years in the median, ulnar, radial, tibial, peroneal and sural nerves. Height, weight, age, handedness and gender were recorded, the volume of the hands was measured using the water displacement method. The intra-nerve CSA variability (INV), left/right ratios and absolute differences were calculated. Age groups were compared by the Kruskal-Wallis test. The influence of demographic factors was analyzed using Spearman correlation and multiple linear regression. Echogenicity and fraction of black were determined for each nerve segment.

Results

Nerve CSA values were consistently lower than those reported for adults and correlated in all measured nerve sites with age, height, weight and hand volume. Weight showed the highest correlation coefficient (R = .95) with the best fitting model predicting CSA. Correlation coefficients were higher in a linear than in a logarithmic model. Ratios were stable, the absolute differences increased with age and were significantly different between age groups. Most nerves showed a mixed or hypoechogenic pattern in echogenicity analysis, hyperechogenicity is less frequently observed.

Conclusions

Nerve CSA in children and adolescents is lower than in adults and increases proportionally during growth with a constant INV and left/right ratio in different age groups. Weight and age are predominant anthropometric factors predicting nerve size. Hand volume is correlated with nerve size, but does not predict CSA independently. Echogenicity can provide additional information on nerve structure.

Nerve Ultrasound Score in Chronic Inflammatory Demyelinating Polyneuropathy

Background and Objectives: Studies have suggested that, by applying certain nerve ultrasound scores, demyelinating and axonal polyneuropathies can be differentiated. In the current study, we investigated the utility of ultrasound pattern sub-score A (UPSA) and intra- and internerve cross-sectional area (CSA) variability in the diagnostic evaluation of demyelinating neuropathies. Materials and Methods: Nerve ultrasound was performed in patients with chronic inflammatory demyelinating polyneuropathy (CIDP) and acute inflammatory demyelinating polyneuropathy (AIDP) and compared to patients with axonal neuropathies. The UPSA, i.e., the sum of ultrasound scores at eight predefined measurement points in the median (forearm, elbow and mid-arm), ulnar (forearm and mid-arm), tibial (popliteal fossa and ankle) and fibular (lateral popliteal fossa) nerves, was applied. Intra- and internerve CSA variability were defined as maximal CSA/minimal CSA for each nerve and each subject, respectively. Results: A total of 34 CIDP, 15 AIDP and 16 axonal neuropathies (including eight axonal Guillain-Barré syndrome (GBS), four hereditary transthyretin amyloidosis, three diabetic polyneuropathy and one vasculitic neuropathy) were included. A total of 30 age- and sex-matched healthy controls were recruited for comparison. Significantly enlarged nerve CSA was observed in CIDP and AIDP with significantly higher UPSA in CIDP compared to the other groups (9.9 ± 2.9 vs. 5.9 ± 2.0 vs. 4.6 ± 1.9 in AIDP vs. axonal neuropathies, p < 0.001). A total of 89.3% of the patients with CIDP had an UPSA score ≥7 compared to the patients with AIDP (33.3%) and axonal neuropathies (25.0%) (p < 0.001). Using this cut-off, the performance of UPSA in differentiating CIDP from other neuropathies including AIDP was excellent (area under the curve of 0.943) with high sensitivity (89.3%), specificity (85.2%) and positive predictive value (73.5%). There were no significant differences in intra- and internerve CSA variability between the three groups. Conclusion: The UPSA ultrasound score was useful in distinguishing CIDP from other neuropathies compared to nerve CSA alone.

Spinal cord lesion mimicking a dysimmune myelitis revealing CANVAS syndrome

CONTEXT

Posterior spinal cord lesions are found in patients with ganglionopathy. These are normally found in later stages of the neuronopathy as a consequence of dorsal root ganglia degeneration. Cerebellar Ataxia, Neuropathy, Vestibular Areflexia Syndrome (CANVAS) is an emerging neurological disorder. Myelitis lesions have been described in confirmed CANVAS cases.

FINDINGS

We describe a case of a 68-year-old woman with slowly progressive ataxia with paresthesia. Laboratory tests were normal. Total spine MRI showed a C4 posterior spinal cord lesion. Lumbar puncture was positive for oligoclonal bands with normal IgG index and protein level. Paraneoplastic antibodies were not detected. Electromyography showed nonlength dependent sensory neuropathy. The patient was treated with intravenous immunoglobulin for suspected dysimmune myelitis. Over 6 years, she progressively developed other neurological manifestations evoking CANVAS. Nerve conduction study showed isolated sensory impairment over the years and peripheral nerve ultrasound revealed abnormally small nerves. Further genetic testing confirmed the diagnosis.

CONCLUSION

This is the first case of CANVAS syndrome presenting initially with an isolated spinal cord lesion mimicking dysimmune myelitis. The purpose of this case report is to add to the current literature about this evolving neurological syndrome and to aid clinicians in their diagnostic approach in clinical practice.

Compound muscle action potential duration ratio for differentiation between Charcot-Marie-Tooth disease and CIDP

OBJECTIVE

To elucidate the utility of the proximal to distal compound muscle action potential (CMAP) duration ratio to distinguish between demyelinating Charcot-Marie-Tooth disease (CMT) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) compared with nerve ultrasound.

METHODS

Thirty-nine demyelinating CMT patients and 19 CIDP patients underwent nerve conduction studies (NCS) and nerve ultrasound. NCS parameters including CMAP duration ratio calculated by dividing the value at the proximal site by that at the distal site and nerve cross-sectional area (CSA) measured by ultrasound were compared between the two groups. The diagnostic sensitivity and specificity of each parameter were analysed.

RESULTS

CMT patients showed a significantly lower CMAP duration ratio than CIDP patients (p < 0.05). The area under the curve (AUC) value of the CMAP duration ratio exceeded 0.95 when CMT was considered "positive", and a cut-off value of 1.13 resulted in high diagnostic sensitivity and specificity (84.6 and 100 % for median nerve, 97.4 and 85.7 % for ulnar nerve, respectively), whereas the AUC value of nerve CSA ranged from 0.70 to 0.81.

CONCLUSIONS

The CMAP duration ratio could effectively distinguish between demyelinating CMT and CIDP.

SIGNIFICANCE

Adding the CMAP duration ratio to a routine NCS may improve the accuracy of the diagnosis of demyelinating CMT.

Application and Research Progress of High Frequency Ultrasound in the Diagnosis of Chronic Inflammatory Neuropathies

In recent years, clinicians have gradually improved their understanding of multiple neuropathy and have done some studies about chronic inflammatory neuropathies, for example, chronic inflammatory demyelinating polyneuropathy, multifocal motor neuropathy, and Lewis-Sumne syndrome. The early diagnosis is very important for the next step treatment and long-term prognosis. At present, the disease mainly depends on clinical and neural electrophysiological examination, but imaging studies are few. In recent years, with the rapid development of high frequency ultrasound, it could clearly show the morphology of the nerve, and it has been an emerging diagnosis tool of polyneuropathies. This article mainly reviews the application and the latest research progress of high frequency ultrasound in these diseases.

Nerve ultrasound characteristics of immunoglobulin M neuropathy associated with anti-myelin-associated glycoprotein antibodies

INTRODUCTION/AIMS

Immunoglobulin M neuropathy associated with anti-myelin-associated glycoprotein antibody (IgM/anti-MAG) neuropathy typically presents with chronic, distal-dominant symmetrical sensory or sensorimotor deficits. Ultrasonographic studies of IgM/anti-MAG neuropathy are limited, and were all performed on Western populations. We aimed to characterize the nerve ultrasonographic features of IgM/anti-MAG neuropathy in the Japanese population and evaluate whether they differ from the findings of the common subtypes of chronic inflammatory demyelinating polyneuropathy (CIDP).

METHODS

In this cross-sectional study, we retrospectively reviewed medical records and extracted the cross-sectional areas (CSAs) of C5-C7 cervical nerve roots and median and ulnar nerves of 6 IgM/anti-MAG neuropathy patients, 10 typical CIDP (t-CIDP) patients, 5 multifocal CIDP (m-CIDP) patients, and 17 healthy controls (HCs).

RESULTS

Cervical nerve root CSAs were significantly larger at every examined site on both sides in IgM/anti-MAG neuropathy than in m-CIDP and HCs but were comparable to those in t-CIDP. Peripheral nerve enlargements were greatest at common entrapment sites (ie, wrist and elbow) in IgM/anti-MAG neuropathy, a pattern shared with t-CIDP but not with m-CIDP. The degree of nerve enlargement at entrapment sites compared to non-entrapment sites was significantly higher in IgM/anti-MAG neuropathy than in t-CIDP.

DISCUSSION

Our study delineated the ultrasonographic features of IgM/anti-MAG neuropathy in the Japanese population and observed similar characteristics to those of t-CIDP, with subtle differences. Further studies comparing results from various populations are required to optimize the use of nerve ultrasound worldwide.

Moderner Ultraschall in der Diagnostik Neuromuskulärer Erkrankungen

Der neuromuskuläre Ultraschall hat sich in den letzten Jahren zu einem festen Bestandteil in der neurologischen Diagnostik entwickelt. Dazu tragen auch die fortwährende technische Weiterentwicklung der Methode und ihr unkomplizierter und nebenwirkungsfreier Einsatz direkt am Patienten bei. Im klinischen Alltag wird der Ultraschall in der Diagnostik und Differentialdiagnostik sowie in der Verlaufskontrolle traumatischer Nervenläsionen, sekundärer und dynamischer nervaler Kompressionssyndrome, hereditärer und akuter sowie chronisch autoimmuner Polyneuropathien, Motoneuron- und Muskelerkrankungen verwendet. Dabei spielt die Ultraschalldiagnostik auch zunehmend eine Rolle für Therapieentscheidungen, v.a. im Hinblick auf die operative Versorgung und den Einsatz oder die Fortführung immunmodulatorischer Medikamente. In den nächsten Jahren ist eine weitere interdisziplinäre Verbreitung und fortwährend zunehmende Standardisierung der Methode zu erwarten.

Ultrasound reference values for peripheral nerve cross-sectional areas and indices in a sample of healthy individuals in Brazil

Objective

To establish peripheral nerve cross-sectional area (CSA) reference values (absolute values, measures of asymmetry, and measures of focality) for healthy individuals in Brazil.

Materials and Methods

Sixty-six healthy volunteers underwent high-resolution ultrasound of the peripheral nerves. We obtained CSA measurements for three peripheral nerves, at specific locations: the median nerve, in the carpal tunnel (MT); the ulnar nerve, at the cubital tunnel site (UT) and at the pre-tunnel site (UPT); and the common fibular nerve, near the fibular head (FH). We calculated the CSA indices between the same sites on different sides (ΔCSAs) and between the ulnar nerve tunnel and pre-tunnel sites on the same side (ΔTPT).

Results

A total of 132 neural sites were analyzed, and the following CSA values (mean ± SD, median) were obtained: MT (6.3 ± 1.9 mm², 6.0 mm²); UT (6.2 ± 1.6 mm², 6.1 mm²); UPT (5.6 ± 1.7 mm², 5.4 mm²); and FH (10.0 ± 3.7 mm², 9.9 mm²). The ΔCSA values (mean ± SD, median) were as follows: MT (0.85 ± 0.7 mm², 0.95); UT (0.81 ± 0.62 mm², 0.95); UPT (0.61 ± 0.51 mm², 0.5); and FH (1.0 ± 0.77 mm², 1.0). The ΔTPT (mean ± SD, median) was (1.0 ± 0.8 mm², 1.0).

Conclusion

Among individuals in Brazil, peripheral nerve CSA values tend to be higher among males and to increase with aging. However, the same does not appear to hold true for the ΔCSA or the ΔTPT, the exception being the difference between the right and left UT. Differences in CSA values greater than 2.5 mm² between sides or between sites along the same nerve can indicate asymmetry or focal thickening in neuropathy, respectively.

Review Article "Spotlight on Ultrasonography in the Diagnosis of Peripheral Nerve Disease: The Evidence to Date"

Neuromuscular ultrasound is rapidly becoming incorporated into clinical practice as a standard tool in the assessment of peripheral nerve diseases. Ultrasound complements clinical phenotyping and electrodiagnostic evaluation, providing critical structural anatomical information to enhance diagnosis and identify structural pathology. This review article examines the evidence supporting neuromuscular ultrasound in the diagnosis of compressive mononeuropathies, traumatic nerve injury, generalised peripheral neuropathy and motor neuron disease. Extending the sonographic evaluation of nerves beyond simple morphological measurements has the potential to improve diagnostics in peripheral neuropathy, as well as advancing the understanding of pathological mechanisms, which in turn will promote precise therapies and improve therapeutic outcomes.

Impact of anatomical variations on ultrasonographic reference values of lower extremity peripheral nerves

INTRODUCTION/AIMS

Cross-sectional area (CSA) reference values using ultrasonography vary widely for lower extremity peripheral nerves. In addition, there is a lack of data on the muscular branches of the tibial nerve and the anatomical variations of the sural nerve. We aimed to evaluate the ultrasonographic reference values for lower extremity peripheral nerves considering different anatomical variations and physical factors.

METHODS

The CSA of the lower extremity nerve was measured at 10 sites. In addition to establishing reference values, differences in the CSA owing to anatomical variations were verified. The relationship between CSA and physical factors, such as age, height, weight, body mass index, and ankle circumference, was also examined.

RESULTS

A total of 100 healthy Japanese volunteers were recruited. The mean CSA of the sural nerve significantly differed depending on its formation pattern (1.4-1.8 mm² ). The mean decreases in CSAs from the proximal to distal tibial and fibular nerves within the popliteal region significantly differed based on the fine branching pattern. The maximum value of the mean decreases in CSAs in the tibial and fibular nerves reached 7.2 and 2.5 mm² , respectively. With respect to physical factors, age and ankle circumferences were associated with CSA at several measurement sites.

DISCUSSION

Fine branching from the tibial and fibular nerves and sural nerve formation may affect CSA measurements. The establishment of accurate CSA reference values requires consideration of anatomical variations in the peripheral nerves of the lower extremity.

Changes of clinical, neurophysiological and nerve ultrasound characteristics in CIDP over time: a 3-year follow-up

OBJECTIVES

To evaluate, in a prospective study, high-resolution ultrasound (HRUS) changes of nerve segments in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and their relationships with clinical and electrodiagnostic (EDX) characteristics.

METHODS

Twenty-three consecutive patients with CIDP were included in a 3-year follow-up (FU) study. Each patient underwent neurologic examination, EDX and HRUS study. HRUS was performed on median, ulnar and peroneal nerves, yielding a total of 319 scanned nerve segments. INCAT and MRC-sum scores, motor nerve conduction velocity (NCV), compound muscle action potential (cMAP) amplitude, and nerve cross-sectional area (NCSA) were collected at baseline and at FU end, and were used for statistical analysis. Twenty-two healthy individuals, matched to patients for age and BMI, served as controls.

RESULTS

NCSA was higher in patients than in controls (p < 0.0001) and showed significant direct correlation with disease severity, and inverse correlation with NCV and cMAP amplitude, both at baseline and at FU end. Disease duration, clinical scores and EDX were predictors of NCSA enlargement at both time points. During FU, NCSA increased in 51% of nerve segments (p = 0.006), in correlation with INCAT increase and with NCV and cMAP reduction. Considering EDX changes in subgroups that reflect the different types of nerve damage, NCSA significantly increased in those nerve segments that from normal EDX switched to prevalent myelinopathic EDX characteristics.

CONCLUSIONS

Peripheral nerve size tends to increase over time in patients with CIDP, in correlation with clinical and EDX changes, in particular in those nerve segments that undergo a predominantly demyelinating damage.

Nerve Ultrasound as Helpful Tool in Polyneuropathies

Background: Polyneuropathies (PNP) are a broad field of diseases affecting millions of people. While the symptoms presented are mostly similar, underlying causes are abundant. Thus, early identification of treatable causes is often difficult. Besides clinical data and basic laboratory findings, nerve conduction studies are crucial for etiological classification, yet limited. Besides Magnetic Resonance Imaging (MRI), high-resolution nerve ultrasound (HRUS) has become a noninvasive, fast, economic and available tool to help distinguish different types of nerve alterations in neuropathies. Methods: We aim to describe typical ultrasound findings in PNP and patterns of morphological changes in hereditary, immune-mediated, diabetic, metabolic and neurodegenerative PNP. Literature research was performed in PubMed using the terms ‘nerve ultrasound’, neuromuscular ultrasound, high-resolution nerve ultrasound, peripheral nerves, nerve enlargement, demyelinating, hereditary, polyneuropathies, hypertrophy’. Results: Plenty of studies over the past 20 years investigated the value of nerve ultrasound in different neuropathies. Next to nerve enlargement, patterns of nerve enlargement, echointensity, vascularization and elastography have been evaluated for diagnostic terms. Furthermore, different scores have been developed to distinguish different etiologies of PNP. Conclusions: Where morphological alterations of the nerves reflect underlying pathologies, early nerve ultrasound might enable a timely start of available treatment and also facilitate follow up of therapy success.

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.

Nerve ultrasound reference data in children from two to seven years

OBJECTIVE

We examined selected peripheral and spinal nerves of children aged between two and seven years.

METHOD

High resolution ultrasound was performed in 116 children (2-7 years of age) at 19 predefined landmarks of median, ulnar, tibial, fibular, sural and radial nerves, the vagus as well as cervical spinal nerve 5 and 6. Further, side-to-side measuring and grey-scale analysis was done at selected nerve sites.

RESULTS

Nerves of children were on average smaller than those of adults. Nerve growth correlates significantly with age in all nerves, the mean values were similar in the age of two to four years and five to seven years. Body mass index (BMI) and gender showed moderate effect at some nerve sites, however not uniformly in all. A side-to-side difference of up to 30% in median, and up to 20% in tibial nerve can occur in healthy individuals. Grey-scale analysis for echointensity has been performed in median, ulnar and tibial nerves.

CONCLUSION

Nerve size increases with age, BMI and gender have moderate effect. A side-to-side-difference of up to 30% can exist.

SIGNIFICANCE

Reference values of nerve cross-sectional area, side-to-side-difference and echo intensity are necessary to detect nerve pathology in children as well as in adults.

Neuropathy associated with immunoglobulin M monoclonal gammopathy: A combined sonographic and nerve conduction study

Introduction

We assessed the specific sonographic pattern of structural nerve abnormalities in immunoglobulin M (IgM) neuropathy and disease controls.

Methods

We enrolled 106 incident patients—32 patients with IgM neuropathy, 42 treatment‐naive patients with chronic inflammatory demyelinating polyneuropathy, and 32 patients with axonal neuropathies. All patients underwent standardized ancillary testing in addition to standardized sonography of the brachial plexus and the large arm and leg nerves bilaterally.

Results

We found widespread nerve enlargement in IgM neuropathy and chronic inflammatory demyelinating polyneuropathy (CIDP), with specific enlargement of brachial plexus and proximal segments of median nerve but not in axonal disease controls (P < .001). Sonographic nerve hypertrophy in IgM neuropathy was not associated with nerve conduction, clinical, or laboratory characteristics.

Discussion

Immunoglobulin M neuropathy is characterized by widespread nerve enlargement indistinguishable from CIDP. Our data provide evidence to confirm that the disease process is not confined to the more distal parts of nerves in either classical demyelinating or axonal variants of neuropathy with associated IgM.

Nerve ultrasound and magnetic resonance imaging in the diagnosis of neuropathy

PURPOSE OF REVIEW

This review summarizes the most relevant developments in the fields of nerve ultrasound and MRI in the diagnosis of treatable inflammatory neuropathies over the last 18 months.

RECENT FINDINGS

MRI and nerve ultrasound can accurately identify potentially treatable neuropathies and thereby help to improve diagnosis. Advanced MRI techniques also show potential to dissect pathophysiology. The apparent mismatch between nerve function and morphology is not surprising and reflects different dimensions of the disease process in neuropathies.

SUMMARY

MRI and nerve ultrasound have become useful tools in the diagnosis of inflammatory neuropathies. VIDEO ABSTRACT.

Nerve echogenicity and intranerve CSA variability in high-resolution nerve ultrasound (HRUS) in chronic inflammatory demyelinating polyneuropathy (CIDP)

OBJECTIVE

HRUS is increasingly being used in the diagnosis and evaluation of autoimmune neuropathies such as CIDP. Recently, studies focused not only on changes of nerves size, but also the fascicular structure and the echogenicity changes in CIDP. However, little is known about the alterations of echogenicity in the long-term course in CIDP. The aim of this study was to evaluate echogenicity in CIDP patients in a long-term follow-up period and to analyze the benefit of the evaluation of echogenicity compared to nerve size.

METHODS

20 patients fulfilling the definite diagnostic criteria of CIDP received clinical examination, nerve conduction studies and HRUS every 6 months over a median follow-up time of 34 months. Patients were divided into clinically stable/regressive disease course or progressive disease course according to the development of the inflammatory neuropathy cause and treatment overall disability sum score. Echogenicity of peripheral nerves was measured semi-automated and quantitative. Echogenicity was divided into three classes by fraction of black: hypoechogenic, mixed hypo-/hyperechogenic, hyperechogenic.

RESULTS

Patients with hyperechogenic arm nerves more frequently show clinical worsening, whereas patients with hypoechogenic arm nerves remain stable or even improved over time. In the long-term course of the disease, echogenicity mostly did not change, and if changes occured echogenicity did not correspond to ODSS changes.

CONCLUSION

Echogenicity of the arm nerves in CIDP may be used as a prognostic marker, but not as a follow-up tool for evaluating clinical changes. Further studies in a larger cohort are needed to confirm these results.

Clinical, Sonographic, and Electrophysiologic Longitudinal Features of Chronic Inflammatory Demyelinating Polyneuropathy

BACKGROUND AND PURPOSE

Several studies have aimed to find potential biomarkers to simplify the diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP) and to monitor and predict the disease course. However, reliable markers are still lacking. We aimed to investigate whether high-resolution nerve ultrasound (HRUS) is suitable for monitoring the long-term clinical course of CIDP.

METHODS

Twenty patients fulfilling the definite diagnostic criteria of CIDP received clinical examination, evaluation of the INCAT (inflammatory neuropathy cause and treatment) overall disability sum score (ODSS) as well as nerve conduction studies, and HRUS every 6 months over a median follow-up time of 34 months. Patients were divided into clinically stable/regressive disease course or progressive disease course according to the development of the ODSS.

RESULTS

The intranerve cross-sectional-area (CSA) variability of the nerves of the lower extremity increased with disease progression, whereas it remained unchanged in patients with a stable or remitting disease course.

CONCLUSION

Nerve ultrasound can be used as a method to objectify the long-term disease course in CIDP patients. The intranerve CSA variability is suitable for monitoring the clinical course of patients with CIDP.

High-Resolution Nerve Ultrasound and Electrophysiological Findings in Restless Legs Syndrome

BACKGROUND AND PURPOSE

Restless legs syndrome (RLS) is a multifactorial network disorder of a sensorimotor system extending from dopaminergic and glutamatergic cerebral structures to the spinal neurons and peripheral nerves. The role of peripheral nerve damage in the causality and severity progression for RLS patients remains unclear.

METHODS

We performed a clinical and epidemiological study on a cohort of 34 RLS patients focusing on RLS risk factors and disease severity. We investigated the peripheral nerves with nerve conduction studies and with high-resolution nerve ultrasound (HRUS).

RESULTS

In 18 of the 34 patients (mean age 67.4 ± 15 years old), a sensorimotor axonal neuropathy was diagnosed. These patients presented with late-onset RLS were treated with membrane stabilizing agents, whereas no neuropathy predisposing comorbidity could be identified for the majority of them. We could show an inverse correlation between the amplitudes of the tibial nerve for the patients with polyneuropathy and the RLS severity index. Neuropathy patients were characterized by an increase of the cross-sectional area (CSA) of the tibial nerve in the popliteal fossa and by increased intranerve and internerve variability values showing an asymmetry of CSA distribution. This pattern resembles previous studies on diabetic neuropathy.

CONCLUSIONS

Early diagnosis, characterization, and treatment of neuropathy are increasingly relevant for RLS patients as it correlates with disease severity. HRUS revealed a pattern resembling diabetic neuropathy, which implies a similar pathophysiology with metabolic and ischemic origin of RLS-related axonal neuropathy.

Nerve ultrasound in polyneuropathies

Ultrasound can be used to visualize pathology in the peripheral nerves of patients with polyneuropathy. Nerve enlargement is the most frequent pathology, but other abnormalities, including abnormal nerve echogenicity and vascularity, are also encountered. This monograph presents an overview of the role of nerve ultrasound in the evaluation and management of both inherited and acquired polyneuropathies. A description of the sonographic techniques and common abnormalities is provided, followed by a presentation of typical findings in different neuropathies. Scoring systems for characterizing the presence and pattern of nerve abnormalities as they relate to different polyneuropathies are presented. Muscle Nerve 57: 716-728, 2018.

The spectrum of Charcot-Marie-Tooth disease due to myelin protein zero: An electrodiagnostic, nerve ultrasound and histological study

OBJECTIVE

Nerve ultrasound (US) data on myelin protein zero (MPZ)-related Charcot-Marie-Tooth disease (CMT) are lacking. To offer a comprehensive perspective on MPZ-related CMTs, we combined nerve US with clinics, electrodiagnosis and histopathology.

METHODS

We recruited 36 patients (12 MPZ mutations), and correlated nerve US to clinical, electrodiagnostic measures, and sural nerve biopsy.

RESULTS

According to motor nerve conduction velocity (MNCV) criteria, nine patients were categorized as "demyelinating" CMT1B, 17 as "axonal" CMT2I/J, and 10 as dominant "intermediate" CMTDID. Sural nerve biopsy showed hypertrophic de-remyelinating neuropathy with numerous complex onion bulbs in one patient, de-remyelinating neuropathy with scanty/absent onion bulbs in three, axonal neuropathy in two, mixed demyelinating-axonal neuropathy in five. Electrodiagnosis significantly differed in CMT1B vs. CMT2I/J and CMTDID subgroups. CMT1B had slightly enlarged nerve cross sectional area (CSA) especially at proximal upper-limb (UL) sites. CSA was negatively correlated to UL MNCV and not increased at entrapment sites. Major sural nerve pathological patterns were uncorrelated to UL nerve US and MNCV.

CONCLUSIONS

Sural nerve biopsy confirmed the wide pathological spectrum of MPZ-CMT. UL nerve US identified two major patterns corresponding to the CMT1B and CMT2I/J-CMTDID subgroups.

SIGNIFICANCE

Nerve US phenotype of MPZ-CMT diverged from those in other demyelinating peripheral neuropathies and may have diagnostic value.

A look inside the nerve - Morphology of nerve fascicles in healthy controls and patients with polyneuropathy

OBJECTIVE

Polyneuropathies are increasingly analyzed by ultrasound. Summarizing, diffuse enlargement is typical in Charcot-Marie Tooth type 1 (CMT1a), regional enlargement occurs in inflammatory neuropathies. However, a distinction of subtypes is still challenging. Therefore, this study focused on fascicle size and pattern in controls and distinct neuropathies.

METHODS

Cross-sectional area (CSA) of the median, ulnar and peroneal nerve (MN, UN, PN) was measured at predefined landmarks in 50 healthy controls, 15 CMT1a and 13 MMN patients. Additionally, largest fascicle size and number of visible fascicles was obtained at the mid-upper arm cross-section of the MN and UN and in the popliteal fossa cross-section of the PN.

RESULTS

Cut-off normal values for fascicle size in the MN, UN and PN were defined (<4.8mm², <2.8mm² and <3.5mm²). In CMT1a CSA and fascicle values are significantly enlarged in all nerves, while in MMN CSA and fascicles are regionally enlarged with predominance in the upper arm nerves. The ratio of enlarged fascicles and all fascicles was significantly increased in CMT1a (>50%) in all nerves (p<0.0001), representing diffuse fascicle enlargement, and moderately increased in MMN (>20%), representing differential fascicle enlargement (enlarged and normal fascicles at the same location) sparing the peroneal nerve (regional fascicle enlargement). Based on these findings distinct fascicle patterns were defined.

CONCLUSION

Normal values for fascicle size could be evaluated; while CMT1a features diffuse fascicle enlargement, MMN shows regional and differential predominance with enlarged fascicles as single pathology.

SIGNIFICANCE

Pattern analysis of fascicles might facilitate distinction of several otherwise similar neuropathies.

Different nerve ultrasound patterns in charcot-marie-tooth types and hereditary neuropathy with liability to pressure palsies

INTRODUCTION

Nerve ultrasound in Charcot-Marie-Tooth (CMT) disease has focused mostly on the upper limbs. We performed an evaluation of a large cohort of CMT patients in which we sonographically characterized nerve abnormalities in different disease types, ages, and nerves.

METHODS

Seventy patients affected by different CMT types and hereditary neuropathy with liability to pressure palsies (HNPP) were evaluated, assessing median, ulnar, fibular, tibial, and sural nerves bilaterally. Data were correlated with age.

RESULTS

Nerve dimensions were correlated with CMT type, age, and nerve site. Nerves were larger in demyelinating than in axonal neuropathies. Nerve involvement was symmetric.

DISCUSSION

CMT1 patients had larger nerves than did patients with other CMT types. Patients with HNPP showed enlargement at entrapment sites. Our study confirms the general symmetry of ultrasound nerve patterns in CMT. When compared with ultrasound studies of nerves of the upper limbs, evaluation of the lower limbs did not provide additional information. Muscle Nerve 57: E18-E23, 2018.

Nerve ultrasound as follow-up tool in treated multifocal motor neuropathy

BACKGROUND AND PURPOSE

High-resolution ultrasound is a valuable tool in supporting the diagnosis of multifocal motor neuropathy (MMN) but longitudinal data under therapy are lacking.

METHODS

The change in peripheral nerve ultrasound pattern in patients with MMN was assessed over time. Patients with MMN received a thorough initial examination and follow-up over a period of 6-12 months using high-resolution ultrasound of the cervical roots and the nerves of the arms and legs, nerve conduction studies, Medical Research Council Sum Score (MRCSS) and Rotterdam Inflammatory Neuropathy Cause and Treatment Group (INCAT) score to evaluate changes under treatment. The Ultrasound Pattern Sum Score (UPSS) was used as standardized peripheral nerve ultrasound protocol.

RESULTS

Seventeen patients with MMN received initial examinations of whom 12 were successfully followed up. All patients with MMN showed at least localized but often multifocal peripheral nerve enlargement. An enlarged overall cross-sectional area as well as enlarged single fascicles (>3 mm²) in clinically and electrophysiologically affected (>90%) and unaffected (>70%) nerves were found. The UPSS did not correlate with clinical disability at both visits. However, the change in clinical disability (evaluated as difference in MRCSS) and the change in UPSS correlated significantly inversely (P = 0.004).

CONCLUSIONS

High-resolution sonography of peripheral nerves revealed multifocal nerve enlargement in MMN. Distinct enlargement patterns may support the diagnosis. Ultrasound findings did not correlate well with clinical severity or electrophysiological findings at initial presentation. As changes in UPSS correlated significantly with the clinical course in terms of muscle strength (MRCSS), sonographic assessment may represent a useful tool for therapeutic monitoring.

The use of ultrasound in neuromuscular diagnoses

Purpose of review

The use of ultrasonography for diagnosis of neuromuscular disorders is a relatively new but rapidly expanding field. This review covers key ultrasound findings in primary disease of muscle and nerve.

Recent findings

Ultrasonography is used routinely for evaluation of entrapment neuropathies, hereditary and inflammatory neuropathies, polyneuropathies, myopathies, and motor neuron disease. When used in association with other electrodiagnostic testing, ultrasound has allowed physicians to increase the yield of clinical evaluation in diagnostic laboratories.

Summary

While ultrasonography has not yet replaced the need for electrodiagnostic studies, it has become a useful accompaniment.

Neuromuscular Ultrasound in the Assessment of Polyneuropathies and Motor Neuron Disease

Neuromuscular ultrasound is an emerging technology for the evaluation of conditions affecting nerve and muscle, with most of the research focusing on focal neuropathies. Despite this focus, researchers have also investigated the ultrasonographic changes that occur in the nerves and muscles of those with more diffuse polyneuropathies and motor neuron diseases, and this review will detail the findings in these conditions. Specific findings are discussed in this article, but general themes will also be presented and include the following: hereditary polyneuropathies show diffuse nerve enlargement, whereas immune-mediated polyneuropathies show more patchy involvement; nerve enlargement is more profound in demyelinating than axonal polyneuropathies; and muscle changes in motor neuron diseases include heterogeneous increases in echogenicity, atrophy, readily detectable fasciculations, and increased subcutaneous tissue thickness.

Evaluation Of freehand high-resolution 3-dimensional ultrasound of the median nerve

INTRODUCTION

In this study we evaluated freehand 3D ultrasound (3DUS) of the median nerve in comparison to 2D ultrasound (2DUS) and assessed the influence of tilting the transversal plane on cross-sectional area (CSA) measurement.

METHODS

Two examiners investigated the median nerves of 22 healthy subjects over a distance of 20 cm using 3DUS. Image quality and CSA were assessed at random points within the virtual 3D volume and compared with 2DUS.

RESULTS

Image quality within the virtual 3D volume was good/sufficient/poor in 53.0%/40.2%/6.8% (examiner 1) and 21.6%/69.6%/8.8% (examiner 2), respectively. CSA measurements with 3DUS were smaller than with 2DUS (-12% and -17%; Wilcoxon test, P < 0.001). Interrater agreement for 3DUS and intermethod agreement between 2DUS and 3DUS were moderate. Stepwise tilting of the transversal plane increased CSA significantly.

CONCLUSION

Freehand 3DUS of the median nerve over 20 cm is feasible and may help overcome some of the limitations and pitfalls of 2DUS. Muscle Nerve 55: 206-212, 2017.

Peripheral Nerve Ultrasonography in Chronic Inflammatory Demyelinating Polyradiculoneuropathy and Multifocal Motor Neuropathy: Correlations with Clinical and Neurophysiological Data

Objective. This cross-sectional study analyzes the pattern of ultrasound peripheral nerve alterations in patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and multifocal motor neuropathy (MMN) at different stages of functional disability. Material and Methods. 22 CIDP and 10 MMN patients and a group of 70 healthy controls were evaluated with an ultrasound scan of the median, ulnar, peroneal, tibial, and sural nerves. Results were correlated with clinical disability scales and nerve conduction studies. Results. Patients with intermediate functional impairment showed relatively larger cross-sectional areas than subjects with either a milder (p < 0.05) or more severe impairment (p < 0.05), both in CIDP and in MMN. In addition, MMN was associated with greater side-to-side intranerve variability (p < 0.05), while higher cross-sectional areas were observed in CIDP (p < 0.05) and in nerve segments with predominantly demyelinating features (p < 0.05). Higher CSA values were observed in nerves with demyelinating features versus axonal damage (p < 0.05 for CIDP; p < 0.05 for MMN). Discussion and Conclusions. Greater extent of quantitative and qualitative US alterations was observed in patients at intermediate versus higher functional disability and in nerves with demyelinating versus axonal damage. CIDP and MMN showed differential US aspects, with greater side-to-side intranerve variability in MMN and higher cross-sectional areas in CIDP.

Ultrasound pattern sum score, homogeneity score and regional nerve enlargement index for differentiation of demyelinating inflammatory and hereditary neuropathies

OBJECTIVE

To investigate the use of nerve ultrasound in the differentiation between Charcot-Marie Tooth hereditary neuropathy (CMT1) and chronic inflammatory demyelinating polyradiculoneuropathies (CIDP), multifocal motor neuropathy (MMN) and multifocal acquired demyelinating sensory and motor neuropathies (MADSAM).

METHODS

Ultrasound/electrophysiology of predefined nerves was performed in CMT1a/b, immunoneuropathies, and healthy controls. Ultrasound pattern sum score (UPSS, sum of the amount of 12 predefined measurement points), homogeneity score (HS) and regional nerve enlargement index (RNEI) in ulnar, median, and tibial nerve were used for evaluation of morphology.

RESULTS

13 CMT1, 27 CIDP, 10 MADSAM, 12 MMN, and 23 controls were included. Significant enlargement was shown in all neuropathies compared to the controls, (p<0.001), however the amount of enlargement as evaluated by the UPSS was most prominent in CMT compared to the others (median UPSS 18 vs. 11/8.5/5 in CIDP/MADSAM/MMN, p<0.001). Homogeneous enlargement was significantly more often seen in CMT (67%, HS 6 vs. 2-3 in immune-mediated PNP, p<0.001), while in CIDP the enlargement was regional, homogeneous or inhomogeneous with equal contribution. In MMN and MADSAM regional enlargement (48%/40%) next to normal segments (∼20%) predominated (RNEI in MMN=2, in MADSAM=1 vs. 0 in the others). CSAs were inversely correlated with motor conduction velocity.

CONCLUSION

Ultrasound, quantified by UPSS, HS, and RNEI facilitates a reliable and reproducible differentiation of immunoneuropathies and hereditary neuropathies by the use of boundary values.

SIGNIFICANCE

By the use of quantitative scores, ultrasound differentiation of demyelinating neuropathies is operationalized and ameliorated compared to CSA measurements only.

Sonographic features of peripheral nerves at multiple sites in patients with diabetic polyneuropathy

OBJECTIVE

Diabetic polyneuropathy (DPN) is one of the major complications of diabetes mellitus. Ultrasound has been frequently used for evaluation of peripheral nerves. However, there are few studies that have evaluated multiple peripheral nerves in DPN. In this study, ultrasonographic features of multiple peripheral nerves in upper and lower extremities of DPN patients were investigated and compared with those of healthy controls.

METHODS

This study was a case-control study that enrolled 20 patients with confirmed diagnosis of DPN and 20 healthy controls. The ultrasonography was performed on the sural, tibial, fibular, sciatic, median, ulnar, radial, and musculocutaneous nerves. Nerve cross-sectional area (CSA) was measured at multiple points for each peripheral nerve. The CSAs were compared between DPN and control groups, and analyzed in relation to the clinical characteristics and electrophysiologic findings.

RESULTS

The CSAs were significantly larger in the DPN group for sural nerve, fibular nerve at the fibular head level, median nerve at the carpal tunnel and mid-humerus level, ulnar nerve at the cubital tunnel outlet and mid-humerus level, and radial nerve at the spiral groove. The CSAs of sural nerve, tibial nerve and median nerve were significantly correlated with electrophysiologic findings. The sural nerve CSA revealed significant correlation with HbA1c.

CONCLUSIONS

These results suggest that the ultrasonography can provide useful information in diagnosis and evaluation of DPN.

High-Resolution Ultrasonography of the Superficial Peroneal Motor and Sural Sensory Nerves May Be a Non-invasive Approach to the Diagnosis of Vasculitic Neuropathy

High-resolution ultrasonography (HRUS) is an emerging new tool in the investigation of peripheral nerves. We set out to assess the utility of HRUS performed at lower extremity nerves in peripheral neuropathies. Nerves of 26 patients with polyneuropathies of different etiologies and 26 controls were investigated using HRUS. Patients underwent clinical, laboratory, electrophysiological assessment, and a diagnostic sural nerve biopsy as part of the routine work-up. HRUS was performed at the sural, tibial, and the common, superficial, and deep peroneal nerves. The superficial peroneal nerve longitudinal diameter (LD) distinguished best between the groups: patients with immune-mediated neuropathies (n = 13, including six with histology-proven vasculitic neuropathy) had larger LD compared to patients with non-immune-mediated neuropathies (p < 0.05) and to controls (p < 0.001). Among all subgroups, patients with vasculitic neuropathy showed the largest superficial peroneal nerve LD (p < 0.001) and had a larger sural nerve cross-sectional area when compared with disease controls (p < 0.001). Enlargement of the superficial peroneal and sural nerves as detected by HRUS may be a useful additional finding in the differential diagnosis of vasculitic and other immune-mediated neuropathies.

Peripheral nerve imaging

Disorders of peripheral nerve have been traditionally diagnosed and monitored using clinical and electrodiagnostic approaches. The last two decades have seen rapid development of both magnetic resonance imaging (MRI) and ultrasound imaging of peripheral nerve, such that these imaging modalities are increasingly invaluable to the diagnosis of patients with peripheral nerve disorders. Peripheral nerve imaging provides information which is supplementary to clinical and electrodiagnostic diagnosis. Both MRI and ultrasound have particular benefits in specific clinical circumstances and can be considered as complementary techniques. These technologic developments in peripheral nerve imaging will usher in an era of multimodality assessment of peripheral nerve disorders, with clinical evaluations supported by anatomic information from imaging, and functional information from electrodiagnostic studies. Such a multimodality approach will improve the accuracy and efficiency of patient care.

Ultrasonography of the peripheral nervous system in the early stage of Guillain-Barré syndrome

Ultrasonography can be used to visualize peripheral nerve abnormalities in immune-mediated neuropathies. The objective of this study was to prove the role of ultrasonography (US) in acute phase of Guillain-Barré syndrome (GBS). Systematic ultrasonic measurements of several peripheral nerves including the vagal nerve as well as the sixth cervical nerve root were performed in 18 patients with GBS at days 1-3 after symptom onset and compared to 21 healthy controls. Nerve conduction studies (NCS) of corresponding nerves were undertaken. Consequently, significant differences between the groups were found in compound muscle action potential amplitudes, F-wave latency, and persistency. Ultrasonic cross-sectional areas (CSAs) showed significant enlargement in all nerves except of the ulnar nerve (upper arm) and the sural nerve compared to healthy controls, most prominent in proximal and middle median nerve (p < 0.01). The vagal nerve also showed enlargement compared to controls (p < 0.05), which was most pronounced in patients with autonomic dysfunction compared to patients without (p < 0.05). C6 root diameter showed a significant correlation to the amount of cerebrospinal fluid (CSF)-protein (Pearson correlation, p < 0.05). US shows nerve enlargement in several peripheral nerves including vagal nerve and C6 root in acute phase of GBS and could be an additional diagnostic tool for example, in GBS of atypical onset and autonomic dysfunction.

Ultrasound in the diagnosis of peripheral neuropathy: structure meets function in the neuromuscular clinic

Peripheral nerve ultrasound (US) has emerged as a promising technique for the diagnosis of peripheral nerve disorders. While most experience with US has been reported in the context of nerve entrapment syndromes, the role of US in the diagnosis of peripheral neuropathy (PN) has recently been explored. Distinctive US findings have been reported in patients with hereditary, immune-mediated, infectious and axonal PN; US may add complementary information to neurophysiological studies in the diagnostic work-up of PN. This review describes the characteristic US findings in PN reported to date and a classification of abnormal nerve US patterns in PN is proposed. Closer scrutiny of nerve abnormalities beyond assessment of nerve calibre may allow for more accurate diagnostic classification of PN, as well as contribute to the understanding of the intersection of structure and function in PN.