Comparison of distortion correction preprocessing pipelines for DTI in the upper limb.

PURPOSE: DTI characterizes tissue microstructure and provides proxy measures of nerve health. Echo-planar imaging is a popular method of acquiring DTI but is susceptible to various artifacts (e.g., susceptibility, motion, and eddy currents), which may be ameliorated via preprocessing. There are many pipelines available but limited data comparing their performance, which provides the rationale for this study. METHODS: DTI was acquired from the upper limb of heathy volunteers at 3T in blip-up and blip-down directions. Data were independently corrected using (i) FSL's TOPUP & eddy, (ii) FSL's TOPUP, (iii) DSI Studio, and (iv) TORTOISE. DTI metrics were extracted from the median, radial, and ulnar nerves and compared (between pipelines) using mixed-effects linear regression. The geometric similarity of corrected b = 0 images and the slice matched T1-weighted (T1w) images were computed using the Sörenson-Dice coefficient. RESULTS: Without preprocessing, the similarity coefficient of the blip-up and blip-down datasets to the T1w was 0·80 and 0·79, respectively. Preprocessing improved the geometric similarity by 1% with no difference between pipelines. Compared to TOPUP & eddy, DSI Studio and TORTOISE generated 2% and 6% lower estimates of fractional anisotropy, and 6% and 13% higher estimates of radial diffusivity, respectively. Estimates of anisotropy from TOPUP & eddy versus TOPUP were not different but TOPUP reduced radial diffusivity by 3%. The agreement of DTI metrics between pipelines was poor. CONCLUSIONS: Preprocessing DTI from the upper limb improves geometric similarity but the choice of the pipeline introduces clinically important variability in diffusion parameter estimates from peripheral nerves.

The Effectiveness of Different Nerve Transfers in the Restoration of Elbow Flexion in Adults Following Brachial Plexus Injury: A Systematic Review and Meta-Analysis.

PURPOSE: Restoration of elbow flexion is an important goal in the treatment of patients with traumatic brachial plexus injury. Numerous studies have described various nerve transfers for neurotization of the musculocutaneous nerve (or its motor branches); however, there is uncertainty over the effectiveness of each method. The aim of this study was to summarize the published evidence in adults with traumatic brachial plexus injury. METHODS: Medline, Embase, medRxiv, and bioRxiv were systematically searched from inception to April 12, 2021. We included studies that reported the outcomes of nerve transfers for the restoration of elbow flexion in adults. The primary outcome was elbow flexion of grade 4 (M4) or higher on the British Medical Research Council scale. Data were pooled using random-effects meta-analyses, and heterogeneity was explored using metaregression. Confidence intervals (CIs) were generated to the 95% level. RESULTS: We included 64 articles, which described 13 different nerve transfers. There were 1,335 adults, of whom 813 (61%) had partial and 522 (39%) had pan-plexus injuries. Overall, 75% of the patients with partial brachial plexus injuries achieved ≥M4 (CI, 69%-80%), and the choice of donor nerve was associated with clinically meaningful differences in the outcome. Of the patients with pan-plexus injuries, 45% achieved ≥M4 (CI, 31%-60%), and overall, each month delay from the time of injury to reconstruction reduced the probability of achieving ≥M4 by 7% (CI, 1%-12%). CONCLUSIONS: The choice of donor nerve affects the chance of attaining a British Medical Research Council score of ≥4 in upper-trunk reconstruction. For patients with pan-plexus injuries, delay in neurotization may be detrimental to motor outcomes. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

The Comparative Efficacy of Chlorhexidine Gluconate and Povidone-iodine Antiseptics for the Prevention of Infection in Clean Surgery: A Systematic Review and Network Meta-analysis.

OBJECTIVE: There is uncertainty around preoperative skin antisepsis in clean surgery. Network meta-analysis provides more precise estimates than standard pairwise meta-analysis and can rank interventions by efficacy, to better inform clinical decisions. BACKGROUND: Infection is the most common and costly complication of surgery. The relative efficacy of CHG and PVI based skin antiseptics in clean surgery remains unclear. METHODS: We searched for randomized or nonrandomized studies comparing the effect of different preparations of CHG and PVI on the dichotomous outcome of surgical site infection. We included studies of adults undergoing clean surgery. We excluded studies concerning indwelling vascular catheters, blood sampling, combination antiseptics or sequential applications of different antiseptics. We performed a network meta-analysis to estimate the relative efficacy of interventions using relative risks (RR). RESULTS: We included 17 studies comparing 5 antiseptics in 14,593 individuals. The overall rate of surgical site infection was 3%. Alcoholic CHG 4%-5% was ranked as the most effective antiseptic as it halved the risk of surgical site infection when compared to aqueous PVI [RR 0.49 (95% confidence interval 0.24, 1.02)] and also to alcoholic PVI, although uncertainty was larger [RR 0.51 (95% confidence interval 0.21, 1.27)]. Adverse events related to antiseptic application were only observed with patients exposed to PVI. CONCLUSIONS: Alcoholic formulations of 4%-5% CHG seem to be safe and twice as effective as PVI (alcoholic or aqueous solutions) in preventing infection after clean surgery in adults. Our findings concur with the literature on contaminated and clean-contaminated surgery, and endorse guidelines worldwide which advocate the use of alcoholic CHG for preoperative skin antisepsis. REGISTRATION: PROSPERO ID CRD42018113001.

The Geometry of the roots of the Brachial Plexus.

Diffusion tensor magnetic resonance imaging (DTI) can be used to reconstruct the brachial plexus in 3D via tracts connecting contiguous diffusion tensors with similar primary eigenvector orientations. When creating DTI tractograms, the turning angle of connecting lines (step angle) must be prescribed by the user; however, the literature is lacking detailed geometry of brachial plexus to inform such decisions. Therefore, the spinal cord and brachial plexus of 10 embalmed adult cadavers were exposed bilaterally by posterior dissection. Photographs were taken under standardised conditions and spatially calibrated in MATLAB. The roots of the brachial plexus were traced from the dorsal root entry zone for 5 cm laterally using a 2.5-mm2 Cartesian grid overlay. The trace was composed of points connected by lines, and the turning angle between line segments (the step angle) was resolved. Our data show that the geometry of the roots increased in tortuosity from C5 to T1, with no significant differences between sides. The 1st thoracic root had the most tortuous course, turning through a maximum angle of 56° per 2.5 mm (99% CI 44° to 70°). Significantly higher step angles and greater variability were observed in the medial 2 cm of the roots of the brachial plexus, where the dorsal and ventral rootlets coalesce to form the spinal root. Throughout the brachial plexus, the majority of step angles (>50%) were smaller than 20° and <1% of step angles exceeded 70°. The geometry of the brachial plexus increases in tortuosity from C5 to T1. To reconstruct 99% of tracts representing the roots of the brachial plexus by DTI tractography, users can either customise the step angle per root based on our findings or select a universal threshold of 70°.

MRI for Detecting Root Avulsions in Traumatic Adult Brachial Plexus Injuries: A Systematic Review and Meta-Analysis of Diagnostic Accuracy.

Background Traumatic brachial plexus injuries affect 1% of patients involved in major trauma. MRI is the best test for traumatic brachial plexus injuries, although its ability to differentiate root avulsions (which require urgent reconstructive surgery) from other types of nerve injury remains unknown. Purpose To evaluate the accuracy of MRI for diagnosing root avulsions in adults with traumatic brachial plexus injuries. Materials and Methods For this systematic review, MEDLINE and Embase were searched from inception to August 20, 2018. Studies of adults with traumatic nonpenetrating unilateral brachial plexus injuries were included. The target condition was root avulsion. The index test was preoperative MRI, and the reference standard was surgical exploration. A bivariate meta-analysis was used to estimate summary sensitivities and specificities of MRI for avulsion. Results Eleven studies of 275 adults (mean age, 27 years; 229 men) performed between 1992 and 2016 were included. Most participants had been injured in motorcycle collisions (84%). All studies were at risk of bias, and there were high applicability concerns for the index test (ie, MRI) in four studies given the lack of diagnostic criteria, inadequate descriptions of pulse sequences, and multiplicity of reporting radiologists. Overall, 72% of patients with brachial plexus injuries had at least one root avulsion (interquartile range [IQR]: 53%-86%); meta-analysis of patient-level data was not performed because of sparse and heterogeneous data. With the nerve root as the unit of analysis, 583 of 918 roots were avulsed (median, 55%; IQR: 38%-71%); the mean sensitivity of MRI for root avulsion was 93% (95% confidence interval [CI]: 77%, 98%) with a mean specificity of 72% (95% CI: 42%, 90%). Conclusion On the basis of limited data, MRI offers modest diagnostic accuracy for traumatic brachial plexus root avulsion(s), and early surgical exploration should remain as the preferred method of diagnosis. Published under a CC BY 4.0 license. Online supplemental material is available for this article.

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.

Neurovascular injury from supracondylar fractures in children: a 10-year experience of 762 cases.

We evaluated the management of supracondylar paediatric fractures at our institution over a 10-year period in this retrospective cohort study. In total, 762 children with a supracondylar fracture were treated. The mean age of injury was 5.2 years. The incidence of documented nerve and/or vascular injury was 8.3%. A total of 26 patients had early plastic surgeon involvement; of these, 25 had an open exploration. Eight patients required vein grafting for brachial artery reconstruction for intimal tears. There was one nerve rupture requiring repair and 12 children underwent neurolysis. There were 17 late referrals to the plastic surgery service, of which three were explored (two neurolysis, one neuroma resection and sural nerve grafting). In all cases of nerve injury, the deficit took 7.9 months to recover, indicating a more significant injury than neurapraxia. Early exploration of supracondylar fractures allows direct visualization of the extent of neurovascular injury and immediate intervention.Level of evidence: IV.

Brachial plexus deficits in patients undergoing shoulder arthroplasty.

Background: Nerve deficit following shoulder arthroplasty can cause significant morbidity. We examined the incidence and pattern of nerve injury following shoulder arthroplasty in a University Hospital. Methods: Retrospective review of all patients undergoing shoulder arthroplasty over a five-year period (September 2014 to August 2019). Patients were identified using clinical codes and relevant data extracted by review of patient records. We excluded patients with preoperative nerve injuries. Results: 220 arthroplasties were performed in 210 patients. The overall nerve deficit rate was 2.3% (5/220). Five nerve deficits occurred following reverse total shoulder arthroplasty (rTSA). In two patients, nerve recovery occurred within 12 months. Two patients had persistent deficits at 12 months. One patient had a deficit at seven months, but incomplete follow up. There was no clear documentation of discussions with clinicians specialising in nerve injury. Conclusion: Nerve injury rates in our series for rTSA are low and comparable to systematic review data. We purport that for rTSA, adequate soft tissue releases, careful arm positioning and retraction alongside limiting over-lowering the centre of rotation may prevent nerve injuries. A postoperative nerve deficit should warrant an opinion from a specialist in nerve surgery with clear referral pathways to allow efficient access to services.

Demographics and deprivation in obstetric brachial plexus palsy: a retrospective cohort study.

The present study analyses the relationships between deprivation and obstetric brachial plexus palsy (OBPP). A retrospective observational study was conducted of infants with OBPP seen between 2008 and 2020 (n = 321). The index of multiple deprivation (IMD) was used to assign an IMD rank to patients based on birth postcode and the relationship with OBPP was analysed, including deprivation, gestational diabetes, age at referral and at first assessment. Quintile-based analysis demonstrated over-representation of patients from more deprived neighbourhoods (n = 109, 39%) living in the top 20% most deprived neighbourhoods. A total of 48 (15%) mothers had diabetes and 98 (31%) infants underwent surgical brachial plexus exploration (a marker of disease severity). Neither diabetes, age at referral nor age at first assessment were associated with IMD score. This suggests that neighbourhood deprivation is associated with OBPP, though the mechanisms are unclear. Further studies in this area may enable targeted health intervention for more deprived maternal and infant groups.Level of evidence: III.

Meta-analysis of the normal diffusion tensor imaging values of the peripheral nerves in the upper limb.

Peripheral neuropathy affects 1 in 10 adults over the age of 40 years. Given the absence of a reliable diagnostic test for peripheral neuropathy, there has been a surge of research into diffusion tensor imaging (DTI) because it characterises nerve microstructure and provides reproducible proxy measures of myelination, axon diameter, fibre density and organisation. Before researchers and clinicians can reliably use diffusion tensor imaging to assess the 'health' of the major nerves of the upper limb, we must understand the "normal" range of values and how they vary with experimental conditions. We searched PubMed, Embase, medRxiv and bioRxiv for studies which reported the findings of DTI of the upper limb in healthy adults. Four review authors independently triple extracted data. Using the meta suite of Stata 17, we estimated the normal fractional anisotropy (FA) and diffusivity (mean, MD; radial, RD; axial AD) values of the median, radial and ulnar nerve in the arm, elbow and forearm. Using meta-regression, we explored how DTI metrics varied with age and experimental conditions. We included 20 studies reporting data from 391 limbs, belonging to 346 adults (189 males and 154 females, ~ 1.2 M:1F) of mean age 34 years (median 31, range 20-80). In the arm, there was no difference in the FA (pooled mean 0.59 mm2/s [95% CI 0.57, 0.62]; I2 98%) or MD (pooled mean 1.13 × 10-3 mm2/s [95% CI 1.08, 1.18]; I2 99%) of the median, radial and ulnar nerves. Around the elbow, the ulnar nerve had a 12% lower FA than the median and radial nerves (95% CI - 0.25, 0.00) and significantly higher MD, RD and AD. In the forearm, the FA (pooled mean 0.55 [95% CI 0.59, 0.64]; I2 96%) and MD (pooled mean 1.03 × 10-3 mm2/s [95% CI 0.94, 1.12]; I2 99%) of the three nerves were similar. Multivariable meta regression showed that the b-value, TE, TR, spatial resolution and age of the subject were clinically important moderators of DTI parameters in peripheral nerves. We show that subject age, as well as the b-value, TE, TR and spatial resolution are important moderators of DTI metrics from healthy nerves in the adult upper limb. The normal ranges shown here may inform future clinical and research studies.

Microsurgical Reconstruction for Reanimation of Foot Dorsiflexion in Children.

Foot drop is a debilitating condition, which causes physical disability and psychological challenges associated with difficulties walking. We report the indications, novel technique, and successful outcomes of two children (three limbs) who underwent free functional gracilis muscle transfers coaptated to the common peroneal nerve to reanimate active foot dorsiflexion and correct foot drop secondary to loss of the anterior compartment.

Combination of a free vascularised fibula and the Masquelet technique for long bone ulna defect reconstruction: A case report.

We present a case of spontaneous osteomyelitis of the left ulna in a 25-year-old man. There was no history of trauma or haematogenous source identified. Bone biopsy found staphylococcus aureus on culture, sensitive to flucloxacillin, but antibiotic treatment was unsuccessful. He underwent excision of the osteomyelitic ulna and a vascularised free fibula graft (VFF graft) reconstruction of the bony defect (18 cm in length), using the ulnar artery at the wrist as recipient vessel. Six months later he was found to have radiological evidence of bony resorption at the proximal fibula-ulnar junction. He underwent resection of a 5 cm segment of the fibula flap and insertion of an antibiotic-impregnated cement spacer in preparation for the placement of bone graft as per Masquelet technique. Following bone graft placement, he united 4 months later. This case demonstrates that the Masquelet technique can be used successfully as an adjunct to VFF graft when reconstructing very long bony defects.

Multidisciplinary reconstructive management of residual recalcitrant empyema cavity: A retrospective observational cohort study.

BACKGROUND: Patients with stage III empyema require chest wall fenestration to enable lung re-expansion and continuous drainage of the persisting empyema cavity. This chronic wound negatively affects patients' exercise tolerance, ability to carry out activities of daily living, and quality of life. METHODS: Eight consecutive patients underwent chest wall reconstruction following fenestration and were followed up over a minimum of 12 months. This study included adult patients (over 18 years of age). There were no exclusion criteria. Data were collected retrospectively. RESULTS: Eight patients (six male and two female), with a mean age of 56 years (range, 22-76), were included. All of them had comorbidities including history of neoplasia (n = 6), atrial fibrillation (n = 3), and hypertension (n = 2). Aetiology of empyema included lung cancer resection complicated by bronchopleural fistula (n = 4), pneumonia (n = 2), and pleural effusion (n = 2). Five patients had a low metabolic reserve evident by a low BMI (range, 16-22), and a median malnutrition universal screen tool (MUST) score of 2 (range, 1-4). Following intensive infection control and nutritional support, patients underwent reconstruction 11 months (median; range 5-51) after fenestration. Seven patients were followed up and had no recurrence of empyema and bronchopleural fistula. They all reported significant improvements in their quality of life, and their Eastern Cooperative Oncology Group (ECOG) performance status improved from three to one. One patient died 56 days post-reconstruction from cardiorespiratory failure, which required readmission to hospital. CONCLUSION: We demonstrate that free tissue reconstruction including multidisciplinary input and optimisation at all stages of care successfully closes residual recalcitrant empyema cavity without recurrence and leads to significant improvements in the quality of life.

Diagnostic accuracy of magnetic resonance imaging for nerve injury in obstetric brachial plexus injury: protocol for systematic review and meta-analysis.

BACKGROUND: Early and accurate clinical diagnosis of the extent of obstetric brachial plexus injury (OBPI) is challenging. The current gold standard for delineating the nerve injury is surgical exploration, and synchronous reconstruction is performed if indicated. Magnetic resonance imaging (MRI) is a non-invasive method of assessing the anatomy and severity of nerve injury in OBPI but the diagnostic accuracy is unclear. The primary objective of this review is to determine the diagnostic accuracy of MRI in comparison to surgical brachial plexus exploration for detecting root avulsion in children under 5 with OBPI. The secondary objectives are to determine its' diagnostic accuracy for detecting nerve abnormality and detecting pseudomeningocele(s) in this group. METHODS: This review will be conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA).We will include studies reporting the accuracy of MRI (index test) compared to surgical exploration (reference standard) in detecting any of the three target conditions (root avulsion, any nerve abnormality and pseudomeningocele) in children under five with OBPI. Case reports and studies where the number of true positives, false positives, true negatives and false negatives cannot be derived will be excluded. We plan to search PubMed, Embase and CENTRAL for relevant studies from database inception to 15 June 2022. We will also search grey literature (medRxiv, bioRxiv and Google Scholar) and perform forward and backward citation chasing. Screening and full-text assessment of eligibility will be conducted by two independent reviewers, who will then both extract the relevant data. The QUADAS-2 tool will be used to assess methodological quality and risk of bias of included studies by two reviewers independently. The following test characteristics for the target conditions will be extracted: true positives, false positives, true negatives and false negatives. Estimates of sensitivity and specificity with 95% confidence intervals will be shown in forest plots for each study. If appropriate, summary sensitivities and specificities for target conditions will be obtained via meta-analyses using a bivariate model. DISCUSSION: This study will aim to clarify the diagnostic accuracy of MRI for detecting nerve injury in OBPI and define its clinical role. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42021267629.

The incidence and spectrum of congenital hand differences in patients with Fanconi anaemia: analysis of 48 patients.

We analysed the spectrum of congenital hand differences in a cohort of patients with Fanconi anaemia (FA). Data of 48 FA patients at the National Cancer Institute were reviewed focusing on age at diagnosis, type and severity of limb difference and any potential association with other known clinical anomalies that are part of the FA phenotype, specifically VACTERL-H and PHENOS. Twenty-eight patients had an upper limb difference, which always included thumb hypoplasia. Twenty-three patients had bilateral upper limb differences, including varying combinations and severities of thumb hypoplasia, radial dysplasia and thumb duplication. Patients with a limb difference were diagnosed at a younger age (<2 years: 15/28 with limb anomaly versus 4/20 without a limb anomaly). However, 7/28 with limb anomalies, usually thumb hypoplasia, were not diagnosed until after 6 years of age. This study demonstrates the broad spectrum of radial ray anomalies within the FA phenotype along with the possibility of either unilateral or bilateral upper limb differences and adds further merit to consideration of screening for FA in all cases of radial ray anomaly.Level of evidence: II.

Determining the real site of peroneal nerve injury with knee dislocation: Earlierier is easier.

Common peroneal nerve (CPN) injury is a recognised complication of traumatic knee dislocation with a direct association between the degree of ligamentous injury and the degree of CPN injury. It is essential explore and repair these injuries in good time to reduce morbidity. Often exploration only involves the portion of this nerve associated with the joint as it courses around the fibular head. However, a recent case highlighted the importance of proximal exploration to its branching point from the sciatic nerve, a known point of fragility, even if other defects have been identified.

Fractional anisotropy thresholding for deterministic tractography of the roots of the brachial plexus.

Diffusion tensor imaging (DTI) metrics, such as the fractional anisotropy (FA) and estimates of diffusivity are sensitive to the microstructure of peripheral nerves and may be displayed as tractograms. However, the ideal conditions for tractography of the roots of the brachial plexus are unclear, which represents the rationale for this study. Ten healthy adults were scanned using a Siemens Prisma (3T) and single-shot echo-planar imaging (b-value 0/1000 s/mm2, 64 directions, 2.5 mm3 with 4 averages; repeated in opposing phase encoding directions). Susceptibility correction and tractography were performed in DSI Studio by two independent raters. The effect of FA thresholding at increments of 0.01 (from 0.04 to 0.10) were tested. The mean FA varied between subjects by 2% (95% CI 1%, 3%). FA thresholds of 0.04, 0.05 and 0.06 all propagated 96% of tracts representing the roots; thresholding at 0.07 yielded 4% fewer tracts (p = 0.2), 0.08 yielded 11% fewer tracts (p = 0.008), 0.09 yielded 15% fewer tracts (p = 0.001) and 0.1 yielded 20% fewer tracts (p < 0.001). There was < 0.1% inter-rater variability in the measured FA and 99% agreement for tractography (κ = 0.92, p < 0.001). The fractional anisotropy thresholds required to generate tractograms of the roots of the brachial plexus appears to be lower than those used in the brain. We provide estimates of the probability of generating true tracts for each spinal nerve root of the brachial plexus, at different fractional anisotropy thresholds.

Functional deficits as a result of brachial plexus injury in anterior shoulder dislocation.

The incidence of brachial plexus injuries in anterior shoulder dislocation remains relatively uncommon. A retrospective study was conducted to observe the natural neurological recovery of patients following these injuries over a 2-year period. Muscle power according to the Medical Research Council scale and sensation were measured from presentation to discharge. In 28 patients, the power grade of proximal muscles supplied by nine injured nerves failed to improve over a median follow-up of 5 months. There was no statistically significant improvement in sensation over a median follow-up of 6 months. Poorer recovery in muscle power score was related to advancing age, whereby every decade increased the risk by approximately 30%. Anterior shoulder dislocation with a plexus injury carries a risk of permanent nerve injury. Patients should be referred for specialist nerve assessment leading to rehabilitation and timely early nerve reconstruction, if indicated.Level of evidence: IV.

Diffusion tensor imaging in cubital tunnel syndrome.

Cubital tunnel syndrome (CuTS) is the 2nd most common compressive neuropathy. To improve both diagnosis and the selection of patients for surgery, there is a pressing need to develop a reliable and objective test of ulnar nerve 'health'. Diffusion tensor imaging (DTI) characterises tissue microstructure and may identify differences in the normal ulnar from those affected by CuTS. The aim of this study was to compare the DTI metrics from the ulnar nerves of healthy (asymptomatic) adults and patients with CuTS awaiting surgery. DTI was acquired at 3.0 T using single-shot echo-planar imaging (55 axial slices, 3 mm thick, 1.5 mm2 in-plane) with 30 diffusion sensitising gradient directions, a b-value of 800 s/mm2 and 4 signal averages. The sequence was repeated with the phase-encoding direction reversed. Data were combined and corrected using the FMRIB Software Library (FSL) and reconstructed using generalized q-sampling imaging in DSI Studio. Throughout the length of the ulnar nerve, the fractional anisotropy (FA), quantitative anisotropy (QA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) were extracted, then compared using mixed-effects linear regression. Thirteen healthy controls (8 males, 5 females) and 8 patients with CuTS (6 males, 2 females) completed the study. Throughout the length of the ulnar nerve, diffusion was more isotropic in patients with CuTS. Overall, patients with CuTS had a 6% lower FA than controls, with the largest difference observed proximal to the cubital tunnel (mean difference 0.087 [95% CI 0.035, 0.141]). Patients with CuTS also had a higher RD than controls, with the largest disparity observed within the forearm (mean difference 0.252 × 10-4 mm2/s [95% CI 0.085 × 10-4, 0.419 × 10-4]). There were no significant differences between patients and controls in QA, MD or AD. Throughout the length of the ulnar nerve, the fractional anisotropy and radial diffusivity in patients with CuTS are different to healthy controls. These findings suggest that DTI may provide an objective assessment of the ulnar nerve and potentially, improve the management of CuTS.

Incidental findings associated with magnetic resonance imaging of the brachial plexus.

OBJECTIVE: The identification and management of incidental findings is becoming increasingly problematic, particularly in relation to brachial plexus imaging because the prevalence is unknown. Therefore, we aimed to estimate the prevalence of incidental findings in symptomatic patients undergoing MRI of the brachial plexus. METHODS: This retrospective cohort study included all children and adults who underwent MRI over a 12-year period, in a tertiary care centre in the UK. An incidental finding was any abnormality which was not a direct injury to or disease-process of the brachial plexus. An "incidentaloma" was defined by the need for further investigation or treatment. Multivariable logistic regression was used to estimate the odds ratio (OR) of an "incidentaloma". To estimate which factors were associated with the incident rate ratio (IRR) of incidental findings, multivariable Poisson regression was used. RESULTS: Overall, 502 scans (72%) reported incidental anomalies. Although the number of MRIs performed per annum increased by 23%, the prevalence of "incidentalomas" remained static (p = 0.766). Musculoskeletal incidental findings were the most prevalent (63%) and when identified, there were a median of 3 incidental anomalies per patient. Overall, 125 (18%) anomalies were "incidentalomas" which required further investigation or treatment. The odds of having further investigation or treatment was strongly related to the frequency of incidental findings [adjusted OR 1.16 (95% CI 1.08, 1.24)] and when a tumour was identified [adjusted OR 2.86 (95% CI 1.81, 4.53)]. The number of incidental findings recorded per scan increased when trainees co-reported with consultants [adjusted IRR 0.36 (95% CI 0.05, 0.67)] and in the presence of a tumour [adjusted IRR 0.39 (95% CI 0.28, 0.49)]. CONCLUSIONS: The prevalence of clinically important incidental findings on brachial plexus MRI is lower than organ-specific imaging, but still 18% of scans identified an 'incidentaloma' which required further investigation or treatment. ADVANCES IN KNOWLEDGE: This cohort study shows that approximately 1 in 5 symptomatic patients undergoing a brachial plexus MRI had a clinically important incidental findings, which required further investigation or treatment. This information can be used to inform patients consenting to clinical or research imaging.