Magnetic Resonance Neurography Research Articles

Whole-body magnetic resonance neurography in patients with chronic inflammatory demyelinating polyneuropathy.

Whole-body magnetic resonance neurography (MRN) is an imaging modality that shows peripheral nerve signal change in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). We aimed to explore the diagnostic potential of whole-body MRN and its potential as a monitoring tool after immunotherapy in treatment-naïve CIDP patients. Whole-body MRN using coronal 3-dimensional short tau inversion recovery (STIR) sampling perfection with application-optimized contrasts by using different flip angle evolution (SPACE) techniques was performed in patients being investigated for CIDP and in healthy controls. Baseline clinical neuropathy scales and electrophysiologic parameters were collected, and MRN findings were compared before and after CIDP treatment. We found highly concordant symmetrical thickening and increased T2 signal intensities in the brachial/lumbosacral plexus, femoral, or sciatic nerves in five of the eight patients with a final diagnosis of CIDP and none of the healthy controls. There were no treatment-related imaging changes in five patients with CIDP who completed a follow-up study. Diffuse, symmetrical thickening, and increased T2 signal in root, plexus, and peripheral nerves were found in two patients ultimately excluded due to a diagnosis of polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, skin changes (POEMS) syndrome in addition to signal changes in the muscles, bony lesions, organomegaly, and lymphadenopathy. Whole-body MRN imaging shows promise in detecting abnormalities in proximal nerve segments in patients with CIDP. Future studies evaluating the role of MRN in assessing treatment response should consider follow-up scans after treatment durations of more than 4 months.

Evolution of peripheral nerve changes in early multiple sclerosis—a longitudinal MR neurography study

ObjectivesMultiple sclerosis (MS) is a demyelinating disorder of the central nervous system. Increasing evidence indicates additional peripheral nerve involvement in early and chronic disease stages. To investigate the evolution of peripheral nerve changes in patients first diagnosed with MS using quantitative MR neurography.Materials and methodsThis prospective study included 19 patients with newly diagnosed MS according to the revised McDonald criteria (16 female, mean 30.2 ± 7.1 years) and 19 age-/sex-matched healthy volunteers. High-resolution 3 T MR neurography of the sciatic nerve using a quantitative T2-relaxometry sequence was performed, which yielded the biomarkers of T2 relaxation time (T2app) and proton spin density (PSD). Follow-up scans of patients were performed after median of 12 months (range 7–16). Correlation analyses considered clinical symptoms, intrathecal immunoglobulin synthesis, nerve conduction study, and lesion load on brain and spine MRI.ResultsPatients showed increased T2app and decreased PSD compared to healthy controls at initial diagnosis and follow-up (p < 0.001 each). Compared to the initial scan, T2app further increased in patients at follow-up (p = 0.003). PSD further declined by at least 10% in 9/19 patients and remained stable in another 9/19 patients. Correlation analyses did not yield significant results.ConclusionPeripheral nerve involvement in MS appears at initial diagnosis and continues to evolve within 1 year follow-up with individual dynamics. Quantitative MRN provides non-invasive biomarkers to detect and monitor peripheral nerve changes in MS.

Diffusion tensor imaging in anisotropic tissues: application of reduced gradient vector schemes in peripheral nerves

BackgroundIn contrast to the brain, fibers within peripheral nerves have distinct monodirectional structure questioning the necessity of complex multidirectional gradient vector schemes for DTI. This proof-of-concept study investigated the diagnostic utility of reduced gradient vector schemes in peripheral nerve DTI.MethodsThree-Tesla magnetic resonance neurography of the tibial nerve using 20-vector DTI (DTI20) was performed in 10 healthy volunteers, 12 patients with type 2 diabetes, and 12 age-matched healthy controls. From the full DTI20 dataset, three reduced datasets including only two or three vectors along the x- and/or y- and z-axes were built to calculate major parameters. The influence of nerve angulation and intraneural connective tissue was assessed. The area under the receiver operating characteristics curve (ROC-AUC) was used for analysis.ResultsSimplified datasets achieved excellent diagnostic accuracy equal to DTI20 (ROC-AUC 0.847–0.868, p ≤ 0.005), but compared to DTI20, the reduced models yielded mostly lower absolute values of DTI scalars: median fractional anisotropy (FA) ≤ 0.12; apparent diffusion coefficient (ADC) ≤ 0.25; axial diffusivity ≤ 0.96, radial diffusivity ≤ 0.07). The precision of FA and ADC with the three-vector model was closest to DTI20. Intraneural connective tissue was negatively correlated with FA and ADC (r ≥ -0.49, p < 0.001). Small deviations of nerve angulation had little effect on FA accuracy.ConclusionsIn peripheral nerves, bulk tissue DTI metrics can be approximated with only three predefined gradient vectors along the scanner’s main axes, yielding similar diagnostic accuracy as a 20-vector DTI, resulting in substantial scan time reduction.Relevance statementDTI bulk tissue parameters of peripheral nerves can be calculated with only three predefined gradient vectors at similar diagnostic performance as a standard DTI but providing a substantial scan time reduction.Key points• In peripheral nerves, DTI parameters can be approximated using only three gradient vectors.• The simplified model achieves a similar diagnostic performance as a standard DTI.• The simplified model allows for a significant acceleration of image acquisition.• This can help to introduce multi-b-value DTI techniques into clinical practice.Graphical

450 Inflammatory Brachial Plexitis Mimics Postoperative Iatrogenic Neurological Deficits

INTRODUCTION: A common cause of neurosurgical malpractice cases is the misrepresentation of idiopathic brachial neuritis (incidence: 1/1000) as an iatrogenic neurological insult caused by a surgeon. METHODS: Confirmed postprocedural brachial neuritis patients from a single quaternary care institution were identified and analyzed. RESULTS: We identified 6 (3 female) postprocedural brachial neuritis patients with mean age 63.7 (range 50-75) years. Procedures included 5 cervical spine surgeries (3 multilevel ACDFs, 2 multilevel posterior fusions with laminectomies, 1 multilevel disc arthroplasty) and 1 intrajugular central venous catheter placement. Average time to symptom onset was 1 week post-procedure (range 1 day-2.5 weeks). Initial symptom was moderate-to-severe shoulder (5), arm (4), and/or neck (1) pain. Subsequently, all developed axillary/shoulder weakness; 3 distal arm/hand weakness, 2 winged scapula, and 2 dyspnea/orthopnea. For diagnosis, two patients had confirmatory EMG, 1 had MR neurography confirming plexus inflammation, and 3 had both (positive EMG findings and inflammation on MR Neurography). Average time to accurate diagnosis was 3.1 (range 1.5-5) months. Average number of clinicians seen prior to accurate diagnosis: 5. Treatments included opioids (5), steroids (1), and/or physical therapy (6). All experienced partial pain relief by 1-8 weeks; 2 had persistent pain requiring gabapentin past 6 months. All patients continued to experience motor deficits past 6 months: (4 patients had atrophy and 2-4/5 motor strength in proximal the proximal arm, 1 had distal arm 3/5 motor strength, and 1 had scapular winging). CONCLUSIONS: Postoperative idiopathic brachial plexitis mimics iatrogenic nerve damage following neurosurgical procedures. Recognition of this entity is difficult, and 6 patients at our institution saw on average 5 providers over 3 months prior to accurate diagnosis. Brachial plexitis has a prolonged course with typically only partial recovery at 6 months.

Updates in diagnostic tools for diagnosing nerve injury and compressions.

Predicting prognosis after nerve injury and compression can be challenging, even for the experienced clinician. Although thorough clinical assessment can aid diagnosis, we cannot always be precise about long-term functional recovery of either motor or sensory nerves. To evaluate the severity of nerve injury, surgical exploration remains the gold standard, particularly after iatrogenic injury and major nerve injury from trauma, such as brachial plexus injury. Recently, advances in imaging techniques (ultrasound, magnetic resonance imaging [MRI] and MR neurography) along with multimodality assessment, including electrodiagnostic testing, have allowed us to have a better preoperative understanding of nerve continuity and prediction of nerve health and possible recovery. This article outlines the current and potential roles for clinical assessment, exploratory surgery, electrodiagnostic testing ultrasound and MRI in entrapment neuropathies, inflammatory neuritis and trauma. Emphasis is placed on those modalities that are improving in diagnostic accuracy of nerve assessment before any surgical intervention.

3D SHINKEI MR neurography in evaluation of traumatic brachial plexus

3D SHINKEI neurography is a new sequence for imaging the peripheral nerves. The study aims at assessing traumatic brachial plexus injury using this sequence. Fifty-eight patients with suspected trauma induced brachial plexus injury underwent MR neurography (MRN) imaging in 3D SHINKEI sequence at 3 T. Surgery and intraoperative somatosensory evoked potentials or clinical follow-up results were used as the reference standard. MRN, surgery and electromyography (EMG) findings were recorded at four levels of the brachial plexus-roots, trunks, cords and branches. Fifty-eight patients had pre- or postganglionic injury. The C5–C6 nerve postganglionic segment was the most common (average 42%) among the postganglionic injuries detected by 3D SHINKEI MRN. The diagnostic accuracy (83.75%) and the specificity (90.30%) of MRN higher than that of EMG (p < 0.001). There was no significant difference in the diagnostic sensitivity of MRN compared with EMG (p > 0.05). Eighteen patients with brachial plexus injury underwent surgical exploration after MRN examination and the correlation between MRN and surgery was 66.7%. Due to the high diagnostic accuracy and specificity, 3D SHINKEI MRN can comprehensively display the traumatic brachial plexus injury. This sequence has great potential in the accurate diagnosis of traumatic brachial plexus injury.

Utility of MR Neurography for the Evaluation of Peripheral Trigeminal Neuropathies in the Postoperative Period.

Peripheral trigeminal neuropathies are assessed by MR neurography for presurgical mapping. In this clinical report, we aimed to understand the utility of MR neurography following nerve-repair procedures. We hypothesized that postoperative MR neurography assists in determining nerve integrity, and worsening MR neurography findings will corroborate poor patient outcomes. Ten patients with peripheral trigeminal neuropathy were retrospectively identified after nerve-repair procedures, with postsurgical MR neurography performed from July 2015 to September 2023. Postsurgical MR neurography findings were graded as per postintervention category and subcategories of the Neuropathy Score Reporting and Data System (NS-RADS). Descriptive statistics of demographics, inciting injury, injury severity, NS-RADS scoring, and clinical outcomes were obtained. There were 6 women and 4 men (age range, 25-73 years). Most injuries resulted from third molar removals (8/10), with an average time from the inciting event to nerve-repair surgery of 6.1 (SD, 4.6) months. In Neuropathy Score Reporting and Data System-Injury (NS-RADS I), NS-RADS I-4 injuries (neuroma in continuity) were found in 8/10 patients, and NS-RADS I-5 injuries were found in the remaining patients, all confirmed at surgery. Surgeries performed included microdissection with neurolysis, neuroma excision, and nerve allograft with Axoguard protection. Three patients with expected postsurgical MR neurography findings experienced either partial improvement or complete symptom resolution, while among 7 patient with persistent or recurrent neuropathy on postsurgical MR neurography, one demonstrated partial improvement of sensation, pain, and taste and one experienced only pain improvement; the remaining 5 patients demonstrated no improvement. Postsurgical MR neurography consistently coincided with clinical outcomes related to pain, sensation, and lip biting and speech challenges. Lip biting and speech challenges were most amenable to recovery, even with evidence of persistent nerve pathology on postsurgical MR neurography.

The Comparative Efficacy of Palmitoylethanolamide (PEA) With the Combination of Pregabalin and Nortriptyline on Post-extraction Trigeminal Neuropathy by Using Magnetic Resonance (MR) Neurography: A Randomized Clinical Trial.

Aim The aim of this randomized clinical trial is to compare the efficacy of palmitoylethanolamide (PEA) with the combination of pregabalin and nortriptyline in treating post-extraction trigeminal neuropathy using magnetic resonance neurography (MRN). Methods The present prospective, randomized controlled trial was conducted on 60 patients (20 in each group). In group I (positive control group), a combination of 75 mg of pregabalin and 10 mg of nortriptyline was administered once daily for the duration of 12 weeks. In group II, 600 mg of palmitoylethanolamide was given twice a day. In group III, a combination therapy of the abovementioned drugs was given. The efficacy of the drug was assessed by measuring pain intensity in terms of the numeric rating scale (NRS) (primary outcome)and changes (signal intensity and nerve thickness) in magnetic resonance neurography (secondary outcome) at various intervals of time. The data was collected and subjected to statistical analysis using the Statistical Package for Social Sciences (SPSS)version 25(IBM SPSS Statistics, Armonk, NY)at the significance level of P<0.05. Results A significant decrease in post-drug mean NRS scores was observed in all three groups. In terms of reduction in the mean NRS, the combination group showed the highest reduction. Palmitoylethanolamide significantly reduces pain scores with negligible side effects. Conclusion Palmitoylethanolamide helps in the reduction of mild to moderate pain of painful post-traumatic trigeminal neuropathy (PTTN) with minimal side effects, suggesting that it may be used where the use of the conventional drug is either contraindicated or not feasible.

Improved 3D DESS MR neurography of the lumbosacral plexus with deep learning and geometric image combination reconstruction.

To evaluate the impact of deep learning (DL) reconstruction in enhancing image quality and nerve conspicuity in LSP MRN using DESS sequences. Additionally, a geometric image combination (GIC) method to improve DESS signals' combination was proposed. Adult patients undergoing 3.0 Tesla LSP MRN with DESS were prospectively enrolled. The 3D DESS echoes were separately reconstructed with and without DL and DL-GIC combined reconstructions. In a subset of patients, 3D T2-weighted short tau inversion recovery (STIR-T2w) sequences were also acquired. Three radiologists rated 4 image stacks ('DESS S2', 'DESS S2 DL', 'DESS GIC DL' and 'STIR-T2w DL') for bulk motion, vascular suppression, nerve fascicular architecture, and overall nerve conspicuity. Relative SNR, nerve-to-muscle, -fat, and -vessel contrast ratios were measured. Statistical analysis included ANOVA and Wilcoxon signed-rank tests. p < 0.05 was considered statistically significant. Forty patients (22 females; mean age = 48.6 ± 18.5years) were enrolled. Quantitatively, 'DESS GIC DL' demonstrated superior relative SNR (p < 0.001), while 'DESS S2 DL' exhibited superior nerve-to-background contrast ratio (p value range: 0.002 to < 0.001). Qualitatively, DESS provided superior vascular suppression and depiction of sciatic nerve fascicular architecture but more bulk motion as compared to 'STIR-T2w DL'. 'DESS GIC DL' demonstrated better nerve visualization for several smaller, distal nerve segments than 'DESS S2 DL' and 'STIR-T2w DL'. Application of a DL reconstruction with geometric image combination in DESS MRN improves nerve conspicuity of the LSP, especially for its smaller branch nerves.

Advanced Imaging of the Peripheral Nerves, From the AJR "How We Do It" Special Series.

Advanced imaging of peripheral nerves is occupying an increasingly important role in the diagnostic workup of peripheral nerve disorders. Advances in MR neurography (MRN) and high-resolution ultrasound have addressed historical challenges in peripheral nerve imaging related to nerves' small size and non-linear course, and difficult differentiation from surrounding tissues. Modern MRN depicts neuromuscular anatomy with exquisite contrast resolution, and MRN has become the workhorse imaging modality for peripheral nerve evaluation. MRN protocols vary across institutions and are adjusted in individual patients, although commonly include nerve-selective sequences and diffusion tensor imaging tractography. Ultrasound offers a dynamic, real-time high-resolution assessment of peripheral nerves, and is widely accessible and less costly than MRN. Ultrasound has greater ability to interrogate peripheral nerves at the fascicular level and provides complementary information to MRN. However, ultrasound of peripheral nerves requires substantial skill and experience and is operator-dependent. The two modalities have distinct advantages and disadvantages, and the selection between these depends on the clinical context. This article provides an overview of advanced imaging techniques used for evaluation of peripheral nerves, with attention to MRN and high-resolution ultrasound. We draw on our institutional experience in performing both modalities to highlight technical considerations for optimizing examinations.

Efficacy of MR Neurography of Peripheral Trigeminal Nerves: Correlation of Sunderland Grade versus Neurosensory Testing.

The current reference standard of diagnosis for peripheral trigeminal neuropathies (PTN) is clinical neurosensory testing (NST). MR neurography (MRN) is useful for PTN injury diagnosis, but it has only been studied in small case series. The aim of this study was to evaluate the agreement of Sunderland grades of nerve injury on MRN and NST by using surgical findings and final diagnoses as reference standards. A total of 297 patient records with a chief complaint of PTN neuralgia were identified from the university database, and 70 patients with confirmed NST and MRN findings who underwent surgical nerve repair were included in the analysis. Cohen weighted kappa was used to calculate the strength of the agreement between the 3 modalities. There were 19 men and 51 women, with a mean age of 39.6 years and a standard deviation of 16.9 years. Most (51/70, 73%) injuries resulted from tooth extractions and implants. MRN injury grades agreed with surgical findings in 84.09% (37/44) of cases, and NST injury grades agreed with surgical findings in 74.19% (23/31) of cases. MRN and NST both showed similar agreement with surgery for grades I to III (70% and 71.43%). However, MRN showed a higher rate of agreement with surgery (88.24%) for injury grades IV and V than did NST (75%). MRN can objectively improve preoperative planning in patients with higher-grade nerve injuries.

Management of Spontaneous Spinal CSF Leaks Using Noninvasive Dynamic MR Neurography: A Case Series

AbstractSpontaneous spinal cerebrospinal fluid (CSF) leak presents with orthostatic headache and may lead to formation of subdural collection. Invasive magnetic resonance imaging or computed tomography myelography is routinely used to detect these leaks. Noninvasive dynamic magnetic resonance neurography can also detect these leaks and confirm its resolution post treatment. It includes three-dimensional NerveView, a high-resolution short-tau inversion recovery sequence for better visualization of spinal nerves and leak sites. This article showcases the diagnostic and therapeutic journey of three patients with spontaneous spinal CSF leak all of whom were diagnosed with dynamic magnetic resonance neurography and treated successfully with autologous targeted epidural blood patch. In one case, epidural blood patch was repeated after 2 months for recurrence of the leak.

Needle electromyography does not meaningfully impact findings in MR-neurography/-myography.

Magnetic resonance neurography (MRN) and myography (MRM) are emerging imaging methods for detecting diseases of the peripheral nerve system (PNS). Most patients with PNS diseases also undergo needle electromyography (EMG). This study examined whether EMG led to lesions that were detectable using MRN/MRM and whether these lesions could impair image interpretation. Ten patients who underwent clinically indicated EMG were recruited. MRN/MRM was performed before and 2-6 h after EMG, and if achievable, 2-3 days later. T2 signal intensity (SI) of the tibialis anterior muscle (TA) was quantified, and sizes and SI of the new lesions were measured. Visual rating was performed independently by three neuroradiologists. T2 lesions at the site of needle insertion, defined as focal edema, were detectable in 9/10 patients. The mean edema size was 31.72 mm2 (SD = 14.42 mm2 ) at the first follow-up. Susceptibility-weighted imaging lesions, defined as (micro) hematomas were detected in 5/10 patients (mean size, 23.85 mm2 [SD = 12.59 mm2 ]). General muscle SI of the TA did not differ between pre- and post-EMG examinations. Lesions size was relatively small, and the readers described image interpretation as not impaired by these lesions. This study showed that focal edema and hematomas frequently occurred after needle EMG and could be observed using MRN/MRM. As general muscle SI was not affected and image interpretation was not impaired, we concluded that needle EMG did not interfere with MRN/MRM.

Possibilities of magnetic resonance imaging in visualizing the pudendal nerve in normal and pathological conditions

Until recently, imaging of peripheral nerves was limited from a technical point of view, as there was no established “gold standard” study protocol for the purpose of qualitative visualization of nerve trunks in normal and pathological conditions. With technical advances in magnetic resonance imaging and the advent of specialized high-resolution magnetic resonance neurography, it has become possible to visualize peripheral nerves of varying diameters. A literature search in the Pubmed, Medline, EMBASE, Cochrane Library, and eLibrary databases demonstrated the presence of several studies examining the capabilities of magnetic resonance imaging in visualizing the pudendal nerve in normal and pathological conditions. It must be emphasized that the results of these studies are consistent and largely complement each other. A generalization of the available data on the capabilities of magnetic resonance neurography of the pudendal nerve was the impetus for writing this literature review. Magnetic resonance neurography is a tissue-specific imaging method optimized for assessing the condition of peripheral nerves, including changes in the morphology of their bundle structure, signal, the diameter and length of nerve trunks, which can be caused by both anatomical features and pathological processes. Three-dimensional (3D) imaging is critical for studying the topography of peripheral nerves, identifying areas of compression or traumatic injury, and for preoperative planning. Magnetic resonance imaging in certain modes and sections allows to clearly visualize the pudendal nerve along almost its entire length, determine the nature of its branching and the features of its topographic and anatomical location. The anatomical characteristics of the pudendal nerve and its pathological changes obtained using magnetic resonance neurography can be used in everyday clinical practice by urologists, obstetricians-gynecologists and neurosurgeons for planning surgical interventions.

Imaging Biomarkers of Peripheral Nerves: Focus on Magnetic Resonance Neurography and Ultrasonography.

Peripheral neuropathy is a prevalent and debilitating condition affecting millions of individuals globally. Magnetic resonance neurography (MRN) and ultrasonography (US) are noninvasive methods offering comprehensive visualization of peripheral nerves, using anatomical and functional imaging biomarkers to ensure accurate evaluation. For optimized MRN, superior and high-resolution two-dimensional and three-dimensional imaging protocols are essential. The anatomical MRN and US imaging markers include quantitative measures of nerve and fascicular size and signal, and qualitative markers of course and morphology. Among them, quantitative markers of T2-signal intensity ratio are sensitive to nerve edema-like signal changes, and the T1-mapping technique reveals nerve and muscle tissue fatty and fibrous compositional alterations.The functional markers are derived from physiologic properties of nerves, such as diffusion characteristics or blood flow. They include apparent diffusion coefficient from diffusion-weighted imaging and fractional anisotropy and tractography from diffusion tensor imaging to delve into peripheral nerve microstructure and integrity. Peripheral nerve perfusion using dynamic contrast-enhanced magnetic resonance imaging estimates perfusion parameters, offering insights into nerve health and neuropathies involving edema, inflammation, demyelination, and microvascular alterations in conditions like type 2 diabetes, linking nerve conduction pathophysiology to vascular permeability alterations.Imaging biomarkers thus play a pivotal role in the diagnosis, prognosis, and monitoring of nerve pathologies, thereby ensuring comprehensive assessment and elevating patient care. These biomarkers provide valuable insights into nerve structure, function, and pathophysiology, contributing to the accurate diagnosis and management planning for peripheral neuropathy.

Magnetic resonance neurography in spinal cord injury: Imaging findings and clinical significance.

It is unknown whether changes to the peripheral nervous system following spinal cord injury (SCI) are relevant for functional recovery or the development of neuropathic pain below the level of injury. Magnetic resonance neurography (MRN) at 3 T allows detection and localization of structural and functional nerve damage. This study aimed to combine MRN and clinical assessments in individuals with chronic SCI and nondisabled controls. Twenty participants with chronic SCI and 20 controls matched for gender, age, and body mass index underwent MRN of the L5 dorsal root ganglia (DRG) and the sciatic nerve. DRG volume, sciatic nerve mean cross-sectional area (CSA), fascicular lesion load, and fractional anisotropy (FA), a marker for functional nerve integrity, were calculated. Results were correlated with clinical assessments and nerve conduction studies. Sciatic nerve CSA and lesion load were higher (21.29 ± 5.82 mm2 vs. 14.08 ± 4.62 mm2 , p < 0.001; and 8.70 ± 7.47% vs. 3.60 ± 2.45%, p < 0.001) in individuals with SCI compared to controls, whereas FA was lower (0.55 ± 0.11 vs. 0.63 ± 0.08, p = 0.022). DRG volumes were larger in individuals with SCI who suffered from neuropathic pain compared to those without neuropathic pain (223.7 ± 53.08 mm3 vs. 159.7 ± 55.66 mm3 , p = 0.043). Sciatic MRN parameters correlated with electrophysiological results but did not correlate with the extent of myelopathy or clinical severity of SCI. Individuals with chronic SCI are subject to a decline of structural peripheral nerve integrity that may occur independently from the clinical severity of SCI. Larger volumes of DRG in SCI with neuropathic pain support existing evidence from animal studies on SCI-related neuropathic pain.

Phase angle of bioelectrical impedance analysis as an indicator for diabetic polyneuropathy in type 2 diabetes mellitus.

Due to the heterogenous clinical symptoms and deficits, the diagnosis of diabetic polyneuropathy (DPN) is still difficult in clinical routine leading to increased morbidity and mortality. We studied the correlation of phase angle (PhA) of bioelectrical impedance analysis (BIA) with clinical, laboratory and physical markers of DPN to evaluate PhA as possible diagnostic method for DPN. In this cross-sectional observational study as part of the Heidelberg Study on Diabetes and Complications we examined 104 healthy individuals and 205 patients with type 2 diabetes mellitus (T2D), amongst which 63 had DPN. The PhA was calculated from multi-frequency BIA. Nerve conduction studies (NCS), quantitative sensory testing (QST) and diffusion-weighted magnetic resonance neurography (MRN) to determine fractional anisotropy (FA) reflecting peripheral nerve integrity were performed. T2D patients with DPN had lower PhA values (5.71 ± 0.10) compared to T2D patients without DPN (6.07 ± 0.08, p = 0.007,  + 6.1%) and healthy controls (6.18 ± 0.08, p < 0.001,  + 7.9%). Confounder-adjusted analyses showed correlations of the PhA with conduction velocities and amplitudes of the peroneal (β=0.28; β=0.31, p < 0.001) and tibial nerves (β=0.28; β=0.32, p < 0.001), Z-scores of QST (thermal detection β=0.30, p < 0.05) and the FA (β=0.60, p < 0.001). ROC analysis showed similar performance of PhA in comparison to mentioned diagnostic methods. The study shows that PhA is in comparison to other test systems used, at least an equally good and much easier to handle, investigator independent marker for detection of DPN.

Magnetization transfer ratio of the sciatic nerve differs between patients in type 1 and type 2 diabetes

BackgroundPrevious studies on magnetic resonance neurography (MRN) found different patterns of structural nerve damage in type 1 diabetes (T1D) and type 2 diabetes (T2D). Magnetization transfer ratio (MTR) is a quantitative technique to analyze the macromolecular tissue composition. We compared MTR values of the sciatic nerve in patients with T1D, T2D, and healthy controls (HC).Methods3-T MRN of the right sciatic nerve at thigh level was performed in 14 HC, 10 patients with T1D (3 with diabetic neuropathy), and 28 patients with T2D (10 with diabetic neuropathy). Results were subsequently correlated with clinical and electrophysiological data.ResultsThe sciatic nerve’s MTR was lower in patients with T2D (0.211 ± 0.07, mean ± standard deviation) compared to patients with T1D (T1D 0.285 ± 0.03; p = 0.015) and HC (0.269 ± 0.05; p = 0.039). In patients with T1D, sciatic MTR correlated positively with tibial nerve conduction velocity (NCV; r = 0.71; p = 0.021) and negatively with hemoglobin A1c (r =  − 0.63; p < 0.050). In patients with T2D, we found negative correlations of sciatic nerve’s MTR peroneal NCV (r =  − 0.44; p = 0.031) which remained significant after partial correlation analysis controlled for age and body mass index (r = 0.51; p = 0.016).ConclusionsLower MTR values of the sciatic nerve in T2D compared to T1D and HC and diametrical correlations of MTR values with NCV in T1D and T2D indicate that there are different macromolecular changes and pathophysiological pathways underlying the development of neuropathic nerve damage in T1D and T2D.Trial registrationhttps://classic.clinicaltrials.gov/ct2/show/NCT03022721. 16 January 2017.Relevance statementMagnetization transfer ratio imaging may serve as a non-invasive imaging method to monitor the diseases progress and to encode the pathophysiology of nerve damage in patients with type 1 and type 2 diabetes.Key points• Magnetization transfer imaging detects distinct macromolecular nerve lesion patterns in diabetes patients.• Magnetization transfer ratio was lower in type 2 diabetes compared to type 1 diabetes.• Different pathophysiological mechanisms drive nerve damage in type 1 and 2 diabetes.Graphical

Chapter 2 - The role of imaging in focal neuropathies

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

Chapter 7 - Radial neuropathy

Radial neuropathy is the third most common upper limb mononeuropathy after median and ulnar neuropathies. Muscle weakness, particularly wrist drop, is the main clinical feature of most cases of radial neuropathy, and an understanding of the radial nerve's anatomy generally makes localizing the lesion straightforward. Electrodiagnosis can help confirm a diagnosis of radial neuropathy and may help with more precise localization of the lesion. Nerve imaging with ultrasound or magnetic resonance neurography is increasingly used in diagnosis and is important in patients lacking a history of major arm or shoulder trauma. Radial neuropathy most often occurs in the setting of trauma, although many other uncommon causes have been described. With traumatic lesions, the prognosis for recovery is generally good, and for patients with persistent deficits, rehabilitation and surgical techniques may allow substantial functional improvement.