Consistency is key: influence of skull density ratio distribution on the formation of clinically effective lesions and long-term tremor suppression following treatment with MR-guided focused ultrasound

OBJECTIVE

Skull density ratio (SDR) influences the permeability of the skull to the ultrasound waves used in magnetic resonance-guided focused ultrasound (MRgFUS) for the treatment of tremor. SDR values vary across the skull and the mean value is known to be predictive of sonication thermal increase. The aim of this investigation was to explore the effects of the SDR distribution on clinical outcomes following treatment with MRgFUS.

METHODS

Data from 61 patients with essential or dystonic tremor treated with MRgFUS targeting the ventral intermediate nucleus (Vim) were retrospectively analyzed. Tremor suppression was assessed using the Clinical Rating Scale for Tremor (CRST) and hand tremor score (HTS). Vim ablation volume was measured on the T1-weighted MR image acquired both at 1 day and 12 months after treatment. The numerical distribution of SDR values measured for each element in the ultrasound transducer was quantified by calculating the mean, standard deviation, skewness, entropy, and kurtosis of the SDR histogram. The effect of the SDR metrics on change in CRST and HTS was examined using a linear mixed-effects model. Additionally, the effect of the regional distribution of SDR values was explored in an element-wise analysis between patients with above- and below-average tremor suppression.

RESULTS

A significant positive effect was found between SDR kurtosis and improvement in CRST (β = 0.33, p = 0.004) and HTS (β = 0.38, p < 0.001). The effect was found to be significant at 1 month posttreatment (CRST: β = 0.415, p = 0.008; HTS: β = 0.369, p = 0.016), and at the most recent clinical follow-up (CRST: β = 0.395, p < 0.001; HTS: β = 0.386, p < 0.001). One hundred seventy-one significant elements were identified in the element-wise analysis. The mean percentage difference from the mean SDR in these elements was associated with improvement in CRST (β = 0.27, p < 0.008) and HTS (β = 0.27, p < 0.015). Higher SDR kurtosis was associated with increased lesion volume at 12 months (p = 0.040) and less reduction in volume relative to the day-1 lesion volume (p = 0.007).

CONCLUSIONS

Greater SDR kurtosis was associated with larger, more stable lesions at 12 months posttreatment and increased tremor suppression at long-term follow-up. SDR kurtosis may provide a more meaningful prognostic factor than the mean SDR.

Patient Selection is Critical When Evaluating Candidates for 5-Fraction Stereotactic MRI-Guided Adaptive Radiotherapy (SMART) for Locally Advanced Pancreatic Cancer

PURPOSE/OBJECTIVE(S)

Stereotactic magnetic resonance image-guided adaptive radiotherapy (SMART) allows for the safe delivery of biologically effective doses (BED10 ∼ 100 Gy) to patients with pancreatic cancer who otherwise have limited therapeutic avenues. In this study, we analyze long-term outcomes in the largest cohort of patients with borderline-resectable (BR), locally advanced (LA), or medically inoperable (MI) pancreatic cancer treated with a 5-fraction SMART technique.

MATERIALS/METHODS

A single institution analysis of patients with BR, LA, or MI pancreatic cancer treated with SMART between 2015 and 2021 was performed. Patients with locally recurrent disease, non-adenocarcinoma histology, de-novo metastatic disease, or who did not receive induction chemotherapy were excluded. Baseline and treatment characteristics were collected. Local control (LC), progression free survival (PFS), and overall survival (OS) were calculated using the Kaplan-Meier method, and factors associated with outcomes were evaluated using Cox regression analyses. Oncologic outcomes measured from time of initial diagnosis; local control defined as freedom from local progression.

RESULTS

A total of 129 patients were reviewed. Median age at diagnosis was 67 years. The majority were male (60%) and White (84%). 23% of patients had an ECOG 2. Most patients had LA disease (66%), followed by BR (20%) and MI (14%). Median follow up was 17.0 months (6-61 months). Median LC was not reached, and LC was 81%, 54%, and 48% at 1, 2, and 3-years, respectively. Median PFS was 12.9 months [95% confidence interval 11.8-14.71] with 1, 2, and 3-year PFS of 60%, 20%, and 7%, respectively. Median OS was 17.7 months [15.7-19.7] with 1, 2, and 3-year OS of 78%, 28%, 11%, respectively. On univariate analysis, increased duration of induction chemotherapy had a statistically significant impact on PFS and OS. Those receiving equal to or greater than 4 months of induction chemotherapy had a median OS of 19.2 months [17.2-21.2] as compared to 13.6 [11.9-15.3] for those with less than 4 months.

CONCLUSION

In this patient population which included a large portion of patients with ECOG of 2 or greater and those deemed MI, a 5-fraction SMART regimen yielded durable long-term LC. The impact of increasing duration of induction chemotherapy underlies the importance of patient selection and improved understanding of tumor-specific biology when selecting patient's with locally advanced pancreatic cancer for aggressive local therapy.

Building a tissue-unbiased brain template of fiber orientation distribution and tractography with multimodal registration

PURPOSE

Brain templates provide an essential standard space for statistical analysis of brain structure and function. Despite recent advances, diffusion MRI still lacks a template of fiber orientation distribution (FOD) and tractography that is unbiased for both white and gray matter. Therefore, we aim to build up a set of such templates for better white-matter analysis and joint structural and functional analysis.

METHODS

We have developed a multimodal registration method to leverage the complementary information captured by T1 -weighted, T2 -weighted, and diffusion MRI, so that a coherent transformation is generated to register FODs into a common space and average them into a template. Consequently, the anatomically constrained fiber-tracking method was applied to the FOD template to generate a tractography template. Fiber-centered functional connectivity analysis was then performed as an example of the benefits of such an unbiased template.

RESULTS

Our FOD template preserves fine structural details in white matter and also, importantly, clear folding patterns in the cortex and good contrast in the subcortex. Quantitatively, our templates show better individual-template agreement at the whole-brain scale and segmentation scale. The tractography template aligns well with the gray matter, which led to fiber-centered functional connectivity showing high cross-group consistency.

CONCLUSION

We have proposed a novel methodology for building a tissue-unbiased FOD and anatomically constrained tractography template based on multimodal registration. Our templates provide a standard space and statistical platform for not only white-matter analysis but also joint structural and functional analysis, therefore filling an important gap in multimodal neuroimage analysis.

Bystander LECT2 amyloidosis in tumor nephrectomy

Pathologic evaluation of the non-neoplastic renal parenchyma in tumor nephrectomy specimens is critical and can detect both renal-limited and systemic pathologies. We report the case of a 69-year-old Punjabi male who underwent cytoreductive nephrectomy for advanced renal cell carcinoma after immunotherapy. We detected clinically unexpected leukocyte chemotactic factor 2 (LECT2) amyloidosis during pathologic analysis of the surrounding non-neoplastic renal parenchyma, which was confirmed by mass spectrometry. LECT2 amyloidosis occurs predominantly in Hispanic patients and has only rarely been described in Punjabi patients. This case highlights the importance of careful pathologic evaluation of the non-neoplastic renal parenchyma of nephrectomy specimens and raises awareness that LECT2 amyloidosis can occur outside of the typical demographic of Hispanic patients.

Hippocampal Neuronal Integrity and Functional Connectivity Within the Default Mode Network in Mild Cognitive Impairment: A Multimodal Investigation

Background: In older people with mild cognitive impairment (MCI), the relationship between early changes in functional connectivity and in vivo changes in key neurometabolites is not known. Two established correlates of MCI diagnosis are decreased N-acetylaspartate (NAA) in the hippocampus, indicative of decreased neuronal integrity, and changes in the default mode network (DMN) functional network. If and how these measures interrelate is yet to be established, and such understanding may provide insight into the processes underpinning observed cognitive decline. Objectives: To determine the relationship between NAA levels in the left hippocampus and functional connectivity within the DMN in an aging cohort. Methods: In a sample of 51 participants with MCI and 30 controls, hippocampal NAA was determined using magnetic resonance spectroscopy, and DMN connectivity was quantified using resting-state functional MRI. The association between hippocampal NAA and the DMN functional connectivity was tested within the MCI group and separately within the control group. Results: In the DMN, we showed a significant inverse association between functional connectivity and hippocampal NAA in 20 specific brain connections for patients with MCI. This was despite no evidence of any associations in the healthy control group or group differences in either of these measures alone. Conclusions: This study suggests that decreased neuronal integrity in the hippocampus is associated with functional change within the DMN for those with MCI, in contrast to healthy older adults. These results highlight the potential of multimodal investigations to better understand the processes associated with cognitive decline. Impact statement This study measured activity within the default mode network (DMN) and quantified N-acetylaspartate (NAA), a measure of neuronal integrity, within the hippocampus in participants with mild cognitive impairment (MCI) and healthy controls. In participants with MCI, NAA levels were inversely associated with connectivity between specific regions of the DMN, a relationship not evident in healthy controls. This association was present even in the absence of group differences in DMN connectivity or NAA levels. This research illustrates the possibility of using multiple magnetic resonance modalities for more sensitive measures of early cognitive decline to identify and intervene earlier.

New insights into anatomical connectivity along the anterior–posterior axis of the human hippocampus using in vivo quantitative fibre tracking

The hippocampus supports multiple cognitive functions including episodic memory. Recent work has highlighted functional differences along the anterior–posterior axis of the human hippocampus, but the neuroanatomical underpinnings of these differences remain unclear. We leveraged track-density imaging to systematically examine anatomical connectivity between the cortical mantle and the anterior–posterior axis of the in vivo human hippocampus. We first identified the most highly connected cortical areas and detailed the degree to which they preferentially connect along the anterior–posterior axis of the hippocampus. Then, using a tractography pipeline specifically tailored to measure the location and density of streamline endpoints within the hippocampus, we characterised where these cortical areas preferentially connect within the hippocampus. Our results provide new and detailed insights into how specific regions along the anterior–posterior axis of the hippocampus are associated with different cortical inputs/outputs and provide evidence that both gradients and circumscribed areas of dense extrinsic anatomical connectivity exist within the human hippocampus. These findings inform conceptual debates in the field and emphasise the importance of considering the hippocampus as a heterogeneous structure. Overall, our results represent a major advance in our ability to map the anatomical connectivity of the human hippocampus in vivo and inform our understanding of the neural architecture of hippocampal-dependent memory systems in the human brain.

The brain allows us to perceive and interact with our environment and to create and recall memories about our day-to-day lives. A sea-horse shaped structure in the brain, called the hippocampus, is critical for translating our perceptions into memories, and it does so in coordination with other brain regions. For example, different regions of the cerebral cortex (the outer layer of the brain) support different aspects of cognition, and pathways of information flow between the cerebral cortex and hippocampus underpin the healthy functioning of memory.

Decades of research conducted into the brains of non-human primates show that specific regions of the cerebral cortex anatomically connect with different parts of the hippocampus to support this information flow. These insights form the foundation for existing theoretical models of how networks of neurons in the hippocampus and the cerebral cortex are connected. However, the human cerebral cortex has greatly expanded during our evolution, meaning that patterns of connectivity in the human brain may diverge from those in the brains of non-human primates.

Deciphering human brain circuits in greater detail is crucial if we are to gain a better understanding of the structure and operation of the healthy human brain. However, obtaining comprehensive maps of anatomical connections between the hippocampus and cerebral cortex has been hampered by technical limitations. For example, magnetic resonance imaging (MRI), an approach that can be used to study the living human brain, suffers from insufficient image resolution.

To overcome these issues, Dalton et al. used an imaging technique called diffusion weighted imaging which is used to study white matter pathways in the brain. They developed a tailored approach to create high-resolution maps showing how the hippocampus anatomically connects with the cerebral cortex in the healthy human brain. Dalton et al. produced detailed maps illustrating which areas of the cerebral cortex have high anatomical connectivity with the hippocampus and how different parts of the hippocampus preferentially connect to different neural circuits in the cortex. For example, the experiments demonstrate that highly connected areas in a cortical region called the temporal cortex connect to very specific, circumscribed regions within the hippocampus.

These findings suggest that the hippocampus may consist of different neural circuits, each preferentially linked to defined areas of the cortex which are, in turn, associated with specific aspects of cognition. These observations further our knowledge of hippocampal-dependant memory circuits in the human brain and provide a foundation for the study of memory decline in aging and neurodegenerative diseases.

White matter alterations in focal to bilateral tonic-clonic seizures

We examined the white matter of patients with and without focal to bilateral tonic-clonic seizures (FBTCS), and control participants. A neural network based tract segmentation model (Tractseg) was used to isolate tract-specific, track-weighted tensor-based measurements from the tracts of interest. We compared the group differences in the track-weighted tensor-based measurements derived from whole and hemispheric tracts. We identified several regions that displayed significantly altered white matter in patients with focal epilepsy compared to controls. Furthermore, patients without FBTCS showed significantly increased white matter disruption in the inferior fronto-occipital fascicle and the striato-occipital tract. In contrast, the track-weighted tensor-based measurements from the FBTCS cohort exhibited a stronger resemblance to the healthy controls (compared to the non-FBTCS group). Our findings revealed marked alterations in a range of subcortical tracts considered critical in the genesis of seizures in focal epilepsy. Our novel application of tract-specific, track-weighted tensor-based measurements to a new clinical dataset aided the elucidation of specific tracts that may act as a predictive biomarker to distinguish patients likely to develop FBTCS.

Structural connections between the noradrenergic and cholinergic system shape the dynamics of functional brain networks

Complex cognitive abilities are thought to arise from the ability of the brain to adaptively reconfigure its internal network structure as a function of task demands. Recent work has suggested that this inherent flexibility may in part be conferred by the widespread projections of the ascending arousal systems. While the different components of the ascending arousal system are often studied in isolation, there are anatomical connections between neuromodulatory hubs that we hypothesise are crucial for mediating key features of adaptive network dynamics, such as the balance between integration and segregation. To test this hypothesis, we estimated the strength of structural connectivity between key hubs of the noradrenergic and cholinergic arousal systems (the locus coeruleus [LC] and nucleus basalis of Meynert [nbM], respectively). We then asked whether the strength of structural LC and nbM inter-connectivity was related to individual differences in the emergent, dynamical signatures of functional integration measured from resting state fMRI data, such as network and attractor topography. We observed a significant positive relationship between the strength of white-matter connections between the LC and nbM and the extent of network-level integration following BOLD signal peaks in LC relative to nbM activity. In addition, individuals with denser white-matter streamlines interconnecting neuromodulatory hubs also demonstrated a heightened ability to shift to novel brain states. These results suggest that individuals with stronger structural connectivity between the noradrenergic and cholinergic systems have a greater capacity to mediate the flexible network dynamics required to support complex, adaptive behaviour. Furthermore, our results highlight the underlying static features of the neuromodulatory hubs can impose some constraints on the dynamic features of the brain.

998 IMPROVING COMMUNICATION ON MEDICAL WARD ROUNDS IN PATIENTS WITH LIMITED ENGLISH BY IMPLEMENTING MEDICAL COMMUNICATION CHARTS

Aim

To improve communication on the medical ward round with patients with limited English through implementation of a medical communication chart.

Introduction

King’s College Hospital (KCH), London, is situated in Southwark in which 11% of households have no members that speak English as a first language, 4.1% of London’s population report they do not speak English well. Language barriers impair healthcare delivery including during daily ward rounds. This has been exacerbated by the need for PPE during the SARS-CoV2 pandemic. Effective communication between healthcare teams and patients is essential for high quality, patient-centred care. Communication tools commonly used include online, telephone and face-to-face translation services but these have limitations.

Method

Face-to-face patient questionnaires were conducted in the pre-QIP (baseline) group to assess communication on medical ward rounds. Medical communication charts were designed by adapting pre-existing aids commonly used by speech and language therapy. Charts were translated into commonly spoken languages among KCH inpatients. Patients with limited English were selected from both COVID-19 and non-Covid wards. Pre-intervention and post-intervention questionnaires were completed in three Plan–Do–Study–Act (PDSA) cycles.

Results

At baseline, patients agreed or strongly agreed that the ward round addressed physical symptoms (8/8), concerns or anxieties (7/8), ongoing needs (7/8). Only 2/8 doctors felt they could communicate effectively with patients. In PDSA 1, 4/5 patients reported high satisfaction in communicating physical symptoms, anxieties or concerns pre-intervention with 5/5 post-chart implementation. 5/5 patients reported high satisfaction in communicating ongoing needs pre-intervention but only 3/5 post-intervention. In PDSA 2, 2/5 patients reported increased satisfaction in communicating physical symptoms, concerns or anxieties with 4/4 doctors reporting improved satisfaction in communication in PDSA 2 and 2/3 doctors reporting higher satisfaction in communication in PDSA 3.

Conclusion

Medical communication charts can help in delivering high-quality, patient-centred care in multicultural and multilingual healthcare settings within the NHS.

A robust framework for characterising diffusion metrics of the median and ulnar nerves: Exploiting state-of-the-art tracking methods

Diffusion-weighted imaging has been used to quantify peripheral nerve properties; however, traditional post-processing techniques have several limitations. Advanced neuroimaging techniques, which overcome many of these limitations, have not been applied to peripheral nerves. Here, we use state-of-the-art diffusion analysis tools to reconstruct the median and ulnar nerves and quantify their diffusion properties. Diffusion-weighted MRI scans were obtained from eight healthy adult subjects. Constrained spherical deconvolution was combined with probabilistic fibre tracking to compute track-weighted fibre orientation distribution (TW-FOD). The tensor was computed and used along with the tracks to estimate TW apparent diffusion coefficient (TW-ADC), TW fractional anisotropy (TW-FA), TW axial diffusivity (TW-AD), and TW radial diffusivity (TW-RD). Variability of TW measurements was used to estimate power size information. The population intersession mean (± SD) measurements for the median nerve were TW-FOD 1.30 (±0.17), TW-ADC 1.16 (±0.13) × 10^-3  mm² /s, TW-FA 0.60 (±0.05), TW-AD 2.05 (±0.16) × 10^-3  mm² /s, and TW-RD 0.72 (±0.12) × 10^-3  mm² /s. The corresponding measurements for the ulnar nerve were TW-FOD 1.25 (±0.14), TW-ADC 1.13 (±0.10) × 10^-3  mm² /s, TW-FA 0.56 (±0.06), TW-AD 1.93 (±0.01) × 10^-3  mm² /s, and TW-RD 0.74 (±0.12) × 10^-3  mm² /s. Based on these measurements, a sample size of 37 would be sufficient to detect a 10% difference in any of the measured TW metrics. A sample size of 20 would be large enough to detect within-subject differences as small as 2.9% (TW-AD, ulnar nerve) and between-subject differences as small as 3.8% (TW-AD, ulnar nerve).

Intramuscular fat in children with unilateral cerebral palsy

BACKGROUND

Many children with cerebral palsy develop muscle contractures. The mechanisms of contracture are not well understood. We investigated the possibility that, because fat is stiffer than passive muscle, elevated intramuscular fat contributes to contracture. In this cross-sectional study, we compared the quantity and distribution of intramuscular fat in muscles from typically developing children and children with cerebral palsy who have contractures.

METHODS

mDixon magnetic resonance images were obtained from the legs of 20 ambulant children with unilateral spastic cerebral palsy who had ankle contractures (mean age 11 SD 3 years, 13 male, mean moderate level contracture) and 20 typically developing children (mean age 11 SD 4 years, 13 male). The images were analyzed to quantify the intramuscular fat fraction of the medial gastrocnemius muscles. The amount and distribution of intramuscular fat were compared between muscles of children with cerebral palsy and typically developing children.

FINDINGS

In typically developing children, the medial gastrocnemius muscles had a mean intramuscular fat fraction of 4.7% (SD 1.6%). In children with cerebral palsy, the mean intramuscular fat fractions in the more- and less-affected medial gastrocnemius muscle were 11.4% (8.1%) and 6.9% (3.4%) respectively. There were small but statistically significant regional differences in the distribution of intramuscular fat. There was no evidence of a relationship between intramuscular fat fraction and severity of contracture.

INTERPRETATION

Children with cerebral palsy have higher proportions of intramuscular fat than typically developing children. There is no clear relationship between intramuscular fat fraction and dorsiflexion range of motion in children with cerebral palsy.

Pre-Transplant Marital Status and Hematopoietic Cell Transplantation Outcomes

Background

Evidence about the impact of marital status before hematopoietic cell transplantation (hct) on outcomes after hct is conflicting.

Methods

We identified patients 40 years of age and older within the Center for International Blood and Marrow Transplant Research registry who underwent hct between January 2008 and December 2015. Marital status before hct was declared as one of: married or living with a partner, single (never married), separated or divorced, and widowed. We performed a multivariable analysis to determine the association of marital status with outcomes after hct.

Results

We identified 10,226 allogeneic and 5714 autologous hct cases with, respectively, a median follow-up of 37 months (range: 1-102 months) and 40 months (range: 1-106 months). No association between marital status and overall survival was observed in either the allogeneic (p = 0.58) or autologous (p = 0.17) setting. However, marital status was associated with grades 2-4 acute graft-versus-host disease (gvhd), p < 0.001, and chronic gvhd, p = 0.04. The risk of grades 2-4 acute gvhd was increased in separated compared with married patients [hazard ratio (hr): 1.13; 95% confidence interval (ci): 1.03 to 1.24], and single patients had a reduced risk of grades 2-4 acute gvhd (hr: 0.87; 95% ci: 0.77 to 0.98). The risk of chronic gvhd was lower in widowed compared with married patients (hr: 0.82; 95% ci: 0.67 to 0.99).

Conclusions

Overall survival after hct is not influenced by marital status, but associations were evident between marital status and grades 2-4 acute and chronic gvhd. To better appreciate the effects of marital status and social support, future research should consider using validated scales to measure social support and patient and caregiver reports of caregiver commitment, and to assess health-related quality of life together with health care utilization.

Intramuscular Fat in the Medial Gastrocnemius Muscle of People Who Have Had a Stroke

Objective: To compare intramuscular fat fraction in people who have ankle contractures following stroke with the intramuscular fat fraction in control participants.

Design: mDixon MRI images were used to quantify intramuscular fat fractions in the medial gastrocnemius muscles of people who had experienced a hemiparetic stroke (n = 14, mean age 60 ± 13 years) and control participants (n = 18, mean age 66 ± 12 years).

Results: Intramuscular fat fractions were similar in the paretic and non-paretic sides of stroke patients (mean on paretic side 14.5%, non-paretic side 12.8%, difference 1.6%, 95% confidence interval −0.7 to 4.1%). The intramuscular fat fraction on the paretic side was higher than in the control group (mean intramuscular fat fraction in control muscles 7.6%; difference 7.8%, 95% confidence interval 4.6–10.9%). The difference between intramuscular fat fractions in non-paretic and control legs increased with age. Body mass index was similar in stroke patients and controls. There was no association between medial gastrocnemius intramuscular fat fraction and dorsiflexion range.

Conclusion: Muscles of stroke patients had elevated intramuscular fat fractions compared to muscles from control participants which were not explained by differences in body mass index. There is no clear relationship between intramuscular fat in the medial gastrocnemius muscle and dorsiflexion range of motion.

Architecture of the medial gastrocnemius muscle in people who have had a stroke: A diffusion tensor imaging investigation

People who have had a stroke often develop ankle contractures which may be caused by changes in architecture of calf muscles. Anatomically constrained diffusion tensor imaging has recently been used to make three-dimensional, whole-muscle measurements of muscle architecture. Here, we compared the architecture of the medial gastrocnemius muscle in the paretic and non-paretic sides of people who have had a hemiparetic stroke and control participants using novel imaging techniques.

METHODS

MRI techniques (diffusion tensor imaging and mDixon imaging) were used to obtain muscle volume, fascicle length, pennation angle, physiological cross-sectional area and curvature in 14 stroke patients (mean age 60 SD 13 years) and 18 control participants (mean age 66 SD 12 years).

FINDINGS

On average, the ankle on the paretic side had 11° (95% confidence interval 8 to 13°) less dorsiflexion range than on the non-paretic side, and 6° (1 to 13°) less dorsiflexion range than ankles of control participants. The medial gastrocnemius muscles on the paretic side were, on average, 15% (35.2 cm³, 95% confidence interval 5.2 to 65.2 cm³) smaller in volume than the muscles on the non-paretic side, and 16% (36.9 cm³, 95% confidence interval 3.1 to 70.6 cm³) smaller than in control participants. No statistically significant differences between paretic, non-paretic and control muscles were detected for fascicle length, pennation angle, physiological cross-sectional area or curvature.

CONCLUSIONS

People with hemiparetic stroke and reduced range of motion have, on average, a smaller medial gastrocnemius muscle on the paretic side than on the non-paretic side. Other muscle architectural parameters appear unchanged.

Role of Early Referral and Surgical Intervention in Brachial Plexus Birth Palsy: Awareness Among Obstetricians and Pediatricians in a Teaching Hospital

A cross-sectional study was conducted using a validated and standardized questionnaire answered by willing pediatricians and obstetricians at our university teaching hospitals. Nearly two thirds of the pediatricians (62.8%) and three fourths of the obstetricians (73.6%) continued to accept the terminology of obstetric brachial plexus birth palsy which is a misnomer; 32.6% of pediatricians felt that they were unaware of the current trends in its management. Parental reluctance (23.5%) and inadequate knowledge in current approaches among surgeons and pediatricians (41.2%) were suggested as chief causes for the delay in their adequate referral and management using surgical exploration, nerve grafting, and nerve transfer. The delayed presentations of birth brachial plexus injuries with missed opportunity for optimum treatment can be partly attributed to inadequate information available on definitive guidelines in its management among the stakeholders including parents, primary care physicians, and surgeons.

Muscle architecture in children with cerebral palsy and ankle contractures: an investigation using diffusion tensor imaging

BACKGROUND

Children with cerebral palsy frequently have ankle contractures which may be caused by changes in architecture of calf muscles. Here, we compared the architecture of medial gastrocnemius muscles in children with unilateral cerebral palsy and typically developing children using novel imaging techniques.

METHODS AND PROCEDURES

Muscle volumes, fascicle lengths, pennation angles and physiological cross-sectional areas were measured from diffusion tensor images and mDixon scans obtained from 20 ambulant children with unilateral spastic cerebral palsy who had ankle contractures (age 11 ± 3 years; mean ± standard deviation) and 20 typically developing children (11 ± 4 years).

FINDINGS

In children with cerebral palsy, the more-affected side had, on average, 13° less dorsiflexion range and the medial gastrocnemius muscle had 4.9 mm shorter fascicles, 50 cm³ smaller volume and 9.5 cm² smaller physiological cross-sectional area than the less-affected side. Compared to typically developing children, the more-affected side had 10° less dorsiflexion range and the medial gastrocnemius muscle had 4.2 mm shorter fascicles, 51 cm³ smaller volume and 10 cm² smaller physiological cross-sectional area. We did not detect differences between the less-affected and typically developing legs.

INTERPRETATION

Three-dimensional measurement of whole medial gastrocnemius muscles confirmed that the architecture of muscles on the more-affected side of children with cerebral palsy differs from the less-affected side and from muscles of typically developing children. Reductions in fascicle length, muscle volume and physiological cross-sectional area may contribute to muscle contracture.

Validity and reliability of measurements of aponeurosis dimensions from magnetic resonance images

Muscle performance is closely related to the structure and function of tendons and aponeuroses, the sheet-like, intramuscular parts of tendons. The architecture of aponeuroses has been difficult to study with magnetic resonance imaging (MRI) because these thin, collagen-rich connective tissues have very short transverse relaxation (T2) times and therefore provide a weak signal with conventional MRI sequences. Here, we validated measurements of aponeurosis dimensions from two MRI sequences commonly used in muscle-tendon research (mDixon and T1-weighted images), and an ultrashort echo time (UTE) sequence designed for imaging tissues with short T2 times. MRI-based measurements of aponeurosis width, length, and area of 20 sheep leg muscles were compared to direct measurements made with three-dimensional (3D) quantitative microdissection. The errors in measurement of aponeurosis width relative to the mean width were 1.8% for UTE, 3.7% for T1, and 18.8% for mDixon. For aponeurosis length, the errors were 7.6% for UTE, 1.9% for T1, and 21.0% for mDixon. Measurements from T1 and UTE scans were unbiased, but mDixon scans systematically underestimated widths, lengths, and areas of the aponeuroses. Using the same methods, we then found high inter-rater reliability (intraclass correlation coefficients >0.92 for all measures) of measurements of the dimensions of the central aponeurosis of the human tibialis anterior muscle from T1-weighted scans. We conclude that valid and reliable measurements of aponeurosis dimensions can be obtained from UTE and from T1-weighted scans. When the goal is to study the macroscopic architecture of aponeuroses, UTE does not hold an advantage over T1-weighted imaging.

TBX18 overexpression enhances pacemaker function in a rat subsidiary atrial pacemaker model of sick sinus syndrome

KEY POINTS

The sinoatrial node (SAN) is the primary pacemaker of the heart. SAN dysfunction, or 'sick sinus syndrome', can cause excessively slow heart rates and pauses, leading to exercise limitation and syncope, currently treated by implantation of an electronic pacemaker. 'Biopacemaking' utilises gene therapy to restore pacemaker activity by manipulating gene expression. Overexpressing the HCN pacemaker ion channel has been widely used with limited success. We utilised bradycardic rat subsidiary atrial pacemaker tissue to evaluate alternative gene targets: the Na+ /Ca2+ exchanger NCX1, and the transcription factors TBX3 and TBX18 known to be involved in SAN embryonic development. TBX18 overexpression restored normal SAN function, as assessed by increased rate, improved heart rate stability and restoration of isoprenaline response. TBX3 and NCX1 were not effective in accelerating the rate of subsidiary atrial pacemaker tissue. Gene therapy targeting TBX18 could therefore have the potential to restore pacemaker function in human sick sinus syndrome obviating electronic pacemakers.

ABSTRACT

The sinoatrial node (SAN) is the primary pacemaker of the heart. Disease of the SAN, sick sinus syndrome, causes heart rate instability in the form of bradycardia and pauses, leading to exercise limitation and syncope. Biopacemaking aims to restore pacemaker activity by manipulating gene expression, and approaches utilising HCN channel overexpression have been widely used. We evaluated alternative gene targets for biopacemaking to restore normal SAN pacemaker physiology within bradycardic subsidiary atrial pacemaker (SAP) tissue, using the Na+ /Ca2+ exchanger NCX1, and the transcription factors TBX3 and TBX18. TBX18 expression in SAP tissue restored normal SAN function, as assessed by increased rate (SAN 267.5 ± 13.6 bpm, SAP 144.1 ± 8.6 bpm, SAP-TBX18 214.4 ± 14.4 bpm; P < 0.001), improved heart rate stability (standard deviation of RR intervals fell from 39.3 ± 7.2 ms to 6.9 ± 0.8 ms, P < 0.01; root mean square of successive differences of RR intervals fell from 41.7 ± 8.2 ms to 6.1 ± 1.2 ms, P < 0.01; standard deviation of points perpendicular to the line of identity of Poincaré plots (SD1) fell from 29.5 ± 5.8 ms to 7.9 ± 2.0 ms, P < 0.05) and restoration of isoprenaline response (increases in rates of SAN 65.5 ± 1.3%, SAP 28.4 ± 3.4% and SAP-TBX18 103.3 ± 10.2%; P < 0.001). These changes were driven by a TBX18-induced switch in the dominant HCN isoform in SAP tissue, with a significant upregulation of HCN2 (from 1.01 × 10-5  ± 2.2 × 10-6 to 2.8 × 10-5  ± 4.3 × 10-6 arbitrary units, P < 0.001). Biophysically detailed computer modelling incorporating isoform-specific HCN channel electrophysiology confirmed that the measured changes in HCN abundance could account for the observed changes in beating rates. TBX3 and NCX1 were not effective in accelerating the rate of SAP tissue.

Three-dimensional architecture of the whole human soleus muscle in vivo

Background

Most data on the architecture of the human soleus muscle have been obtained from cadaveric dissection or two-dimensional ultrasound imaging. We present the first comprehensive, quantitative study on the three-dimensional anatomy of the human soleus muscle in vivo using diffusion tensor imaging (DTI) techniques.

Methods

We report three-dimensional fascicle lengths, pennation angles, fascicle curvatures, physiological cross-sectional areas and volumes in four compartments of the soleus at ankle joint angles of 69 ± 12° (plantarflexion, short muscle length; average ± SD across subjects) and 108 ± 7° (dorsiflexion, long muscle length) of six healthy young adults. Microdissection and three-dimensional digitisation on two cadaveric muscles corroborated the compartmentalised structure of the soleus, and confirmed the validity of DTI-based muscle fascicle reconstructions.

Results

The posterior compartments of the soleus comprised 80 ± 5% of the total muscle volume (356 ± 58 cm³). At the short muscle length, the average fascicle length, pennation angle and curvature was 37 ± 8 mm, 31 ± 3° and 17 ± 4 /m, respectively. We did not find differences in fascicle lengths between compartments. However, pennation angles were on average 12° larger (p < 0.01) in the posterior compartments than in the anterior compartments. For every centimetre that the muscle-tendon unit lengthened, fascicle lengths increased by 3.7 ± 0.8 mm, pennation angles decreased by −3.2 ± 0.9° and curvatures decreased by −2.7 ± 0.8 /m. Fascicles in the posterior compartments rotated almost twice as much as in the anterior compartments during passive lengthening.

Discussion

The homogeneity in fascicle lengths and inhomogeneity in pennation angles of the soleus may indicate a functionally different role for the anterior and posterior compartments. The data and techniques presented here demonstrate how DTI can be used to obtain detailed, quantitative measurements of the anatomy of complex skeletal muscles in living humans.

History-dependence of muscle slack length following contraction and stretch in the human vastus lateralis

KEY POINTS

In reduced muscle preparations, the slack length and passive stiffness of muscle fibres have been shown to be influenced by previous muscle contraction or stretch. In human muscles, such behaviours have been inferred from measures of muscle force, joint stiffness and reflex magnitudes and latencies. Using ultrasound imaging, we directly observed that isometric contraction of the vastus lateralis muscle at short lengths reduces the slack lengths of the muscle-tendon unit and muscle fascicles. The effect is apparent 60 s after the contraction. These observations imply that muscle contraction at short lengths causes the formation of bonds which reduce the effective length of structures that generate passive tension in muscles.

ABSTRACT

In reduced muscle preparations, stretch and muscle contraction change the properties of relaxed muscle fibres. In humans, effects of stretch and contraction on properties of relaxed muscles have been inferred from measurements of time taken to develop force, joint stiffness and reflex latencies. The current study used ultrasound imaging to directly observe the effects of stretch and contraction on muscle-tendon slack length and fascicle slack length of the human vastus lateralis muscle in vivo. The muscle was conditioned by (a) strong isometric contractions at long muscle-tendon lengths, (b) strong isometric contractions at short muscle-tendon lengths, (c) weak isometric contractions at long muscle-tendon lengths and (d) slow stretches. One minute after conditioning, ultrasound images were acquired from the relaxed muscle as it was slowly lengthened through its physiological range. The ultrasound image sequences were used to identify muscle-tendon slack angles and fascicle slack lengths. Contraction at short muscle-tendon lengths caused a mean 13.5 degree (95% CI 11.8-15.0 degree) shift in the muscle-tendon slack angle towards shorter muscle-tendon lengths, and a mean 5 mm (95% CI 2-8 mm) reduction in fascicle slack length, compared to the other conditions. A supplementary experiment showed the effect could be demonstrated if the muscle was conditioned by contraction at short lengths but not if the relaxed muscle was held at short lengths, confirming the role of muscle contraction. These observations imply that muscle contraction at short lengths causes the formation of bonds which reduce the effective length of structures that generate passive tension in muscles.

How does passive lengthening change the architecture of the human medial gastrocnemius muscle?

There are few comprehensive investigations of the changes in muscle architecture that accompany muscle contraction or change in muscle length in vivo. For this study, we measured changes in the three-dimensional architecture of the human medial gastrocnemius at the whole muscle level, the fascicle level and the fiber level using anatomical MRI and diffusion tensor imaging (DTI). Data were obtained from eight subjects under relaxed conditions at three muscle lengths. At the whole muscle level, a 5.1% increase in muscle belly length resulted in a reduction in both muscle width (mean change -2.5%) and depth (-4.8%). At the fascicle level, muscle architecture measurements obtained at 3,000 locations per muscle showed that for every millimeter increase in muscle-tendon length above the slack length, average fascicle length increased by 0.46 mm, pennation angle decreased by 0.27° (0.17° in the superficial part and 0.37° in the deep part), and fascicle curvature decreased by 0.18 m^-1 There was no evidence of systematic variation in architecture along the muscle's long axis at any muscle length. At the fiber level, analysis of the diffusion signal showed that passive lengthening of the muscle increased diffusion along fibers and decreased diffusion across fibers. Using these measurements across scales, we show that the complex shape changes that muscle fibers, whole muscles, and aponeuroses of the medial gastrocnemius undergo in vivo cannot be captured by simple geometrical models. This justifies the need for more complex models that link microstructural changes in muscle fibers to macroscopic changes in architecture.NEW & NOTEWORTHY Novel MRI and DTI techniques revealed changes in three-dimensional architecture of the human medial gastrocnemius during passive lengthening. Whole muscle belly width and depth decreased when the muscle lengthened. Fascicle length, pennation, and curvature changed uniformly or near uniformly along the muscle during passive lengthening. Diffusion of water molecules in muscle changes in the same direction as fascicle strains.

Rehabilitation referrals and outcomes in the early period after hematopoietic cell transplantation

In a cohort of inpatient hematopoietic cell transplantation (HCT) recipients, we assessed patterns of referral to rehabilitation treatment, functional performance and short-term outcomes in patients who received post-transplant rehabilitation in comparison with those who did not. Among 201 first-time HCT recipients, 53 (26%) were referred to an inpatient rehabilitation provider, had an assessment of functional performance using the Functional Independence Measure scale and underwent rehabilitation treatments to address functional needs. Patients who received rehabilitation therapy were more likely to be females (P=0.02), older than 60 years of age (P=0.0146), employed (P=0.01), have hypertension (P=0.02), peripheral vascular disease (P=0.01) and pre-transplant Karnofsky Performance Score (KPS) <90 (P=0.02). Mean functional performance scores for transfers and ambulation increased significantly in the group with rehabilitation interventions (P=0.0022 and P<0.0001, respectively). There was no difference between the groups that did and did not receive rehabilitation treatments in 30-day re-admission rates. Patients who are 60 years of age or older, with pre-transplant KPS<90, and pre-transplant hypertension were more likely to be referred for rehabilitation treatments in the early period after HCT. Future studies should be designed to determine the optimal timing and cost effectiveness of functional assessment and rehabilitation treatments in this high-risk population.

Passive transfer of antibodies to the linear epitope 60 kD Ro 273-289 induces features of Sjögren's syndrome in naive mice

Sjögren's syndrome (SS) is an autoimmune inflammatory disease that primarily affects the lacrimal and salivary glands causing dry eyes and mouth. Antibodies to Ro60 are observed frequently in patients with SS; however, the role of these antibodies in SS initiation and progression remains unclear. The sequence Ro60 273-289 (Ro274) is a known B cell epitope of Ro60 and antibodies to this epitope have been observed in a subset of SS patients and in animals immunized with Ro60 protein. Animals immunized with Ro274 linear peptide develop a Sjögren's-like illness. We hypothesized that passive transfer of anti-Ro274-specific immunoglobulin (Ig)G would induce a Sjögren's-like phenotype. To evaluate this hypothesis, we adoptively transferred affinity-purified Ro274 antibodies into naive BALB/c animals, then evaluated salivary gland histology, function and IgG localization 4 days post-transfer. At this time-point, there was no demonstrable mononuclear cell infiltration and salivary glands were histologically normal, but we observed a functional deficit in stimulated salivary flow of animals receiving Ro274 antibodies compared to animals receiving control IgG. Cellular fractionation and enzyme-linked immunosorbent assay revealed Ro274-specific antibodies in the nucleus and cytoplasmic fractions of isolated parotid salivary gland cells that was confirmed by immunohistochemistry. These data support the hypothesis that antibodies to Ro274 deposit in salivary glands can enter intact salivary gland cells and are involved in the dysregulation of salivary flow in SS.

Abstract P2-10-03: Impact of BRCA 1 and 2 Gene Mutation Testing on Surgical Decision-Making in Newly Diagnosed Breast Cancer Patients

BACKGROUND: Breast cancer patients with BRCA 1 or 2 gene mutations demonstrate a high lifetime incidence of a second breast cancer in the contralateral breast. These patients may benefit from a bilateral mastectomy (BLM) with an intent of risk reduction. If provided in the right window between cancer diagnosis and definitive treatment, genetic cancer risk assessment would aid high-risk patients in making an informed decision with respect to planning appropriate surgery.

OBJECTIVE: The purpose of this study is to assess the feasibility of BRCA 1 and BRCA 2 gene mutation testing in the pre-operative setting and to determine whether test results altered final surgical decision. METHODS: Newly diagnosed breast cancer patients referred to the cancer genetics clinic between April 2009 to March 2010 were identified. All patients were sent for genetic cancer risk assessment due to the presence of clinical features suggestive of hereditary breast cancer based on current guidelines. A retrospective chart review of the patients was performed. RESULTS: 81 patients were identified. 6 patients were excluded as they went on to have surgery in a different hospital and were lost to follow up. 3 patients did not meet criteria for genetic testing. 1 patient was excluded as she was scheduled for a BLM prior to being seen in our clinic, and 1 patient was receiving neoadjuvant chemotherapy and hadn't had surgery at the time of data collection. Of the remaining 70 patients, the mean age was 48 years (29-74 years) with 81% being of caucasian race and 11% having Ashkenazi-Jewish ethnicity. 30% had two or more first degree and 68% had two or more second degree relatives with cancer. 29% had a first degree relative who had died of cancer. 74% had a diagnosis of invasive breast cancer, where as 26% only had in-situ disease. Further, 21% had grade 1, 37% with grade 2 and rest with grade 3 tumors. 81% tested negative for BRCA gene mutations, 9% were positive for either BRCA 1/2, 6% had variants of uncertain significance(VUS) and 4% didn't undergo genetic testing for various reasons. It took an average of 9.3 days (4-31 days) to obtain results. 54% of women aged 40 years or younger chose BLM versus 25% of women over 40 (p=0.015). 6.7% of women with low grade breast cancer underwent BLM versus 54% with moderate grade and 34% with high grade cancer (p=0.0098). Based on the BRCA results, 83% of BRCA positive women chose BLM versus 33% of BRCA negative (true negative and VUS) patients (p=0.024). A negative result had a greater influence in favor of a unilateral surgery in 67% of BRCA negative patients. In contrast, majority of women who underwent BLM were not influenced solely by their gene test results.

CONCLUSIONS: Amongst newly diagnosed breast cancer patients, genetic testing for hereditary breast and/or ovarian cancer syndromes can influence surgical decision in a risk-appropriate way. Our results show that genetic cancer risk assessment can be effectively incorporated in newly diagnosed breast cancer patients and can help guide the decision about the optimal surgery without a significant delay. A negative BRCA gene result seemed to help patients reach a decision favoring unilateral surgery.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-10-03.

Attenuation of stress-induced gastric lesions by lansoprazole, PD-136450 and ranitidine in rats

Combining restraint with cold temperature (4°C) consistently induces gastric ulceration in rats after 3.5 h. The cold restraint-stress (CRS) method provides a suitable model for acute ulcer investigations. This study compares the antiulcer activities of lansoprazole (a proton pump inhibitor), PD-136450 (CCK(2)/gastrin receptor antagonist) and ranitidine (histamine H(2) receptor antagonist) on CRS-induced gastric ulcers in rats. The results have shown that lansoprazole, which is a potent anti-secretory agent, provides complete protection in this model of ulcer formation. The use of indomethacin pretreatment to inhibit the prostaglandin (PG) synthesis and N(G)-nitro L-arginine methyl ester (L-NAME) pretreatment to inhibit nitric oxide synthase did not alter the lansoprazole-induced inhibition of ulcer index obtained in the untreated Wistar rats indicating that these two systems were not involved in the activation of lansoprazole. PD-136450, an effective anti-secretory agent against gastrin- but not dimaprit-induced stimulation, evoked a dose-dependent inhibition of CRS-induced gastric ulcers. The results show that both PG and nitric oxide pathways can influence the inhibitory effect of PD-136450 against CRS-induced gastric ulcer. The antiulcer activities of both lansoprazole and PD-136450 were compared to that of ranitidine. The results showed that ranitidine was more potent than lansoprazole and PD-136450 in inhibiting CRS-induced gastric ulcers and its effect was shown to be influenced by PG as well as nitric oxide synthase. The results of this study have demonstrated that although lansoprazole, PD-136450 and ranitidine were protective against CRS-induced gastric ulcers, the antiulcer activities of PD-136450 and ranitidine involved both PG and nitric oxide pathways, while lansoprazole acted independently of these two systems during CRS.

Complete complement deficiency in a large cohort of familial systemic lupus erythematosus

Genetic complete deficiency of the early complement components such as C1, C2 and C4 commonly results in a monogenetic form of systemic lupus erythematosus (SLE). However, previous studies have examined groups of complete complement deficient subjects for SLE, while a familial SLE cohort has not been studied for deficiencies of complement. Thus, we undertook the present study to determine the frequency of hereditary complete complement deficiencies among families with two or more SLE patients. All SLE patients from 544 such families had CH50 determined. Medical records were examined for past CH50 values. There were 66 individuals in whom all available CH50 values were zero. All but four of these had a SLE-affected relative with a non-zero CH50; thus, these families did not have monogenetic complement deficient related SLE. The four remaining SLE-affected subjects were in fact two sets of siblings in which three of the four SLE patients had onset of disease at <18 years of age. Both patients in one of these families had been determined to have C4 deficiency, while the other family had no clinical diagnosis of complement deficiency. In this second family, one of the SLE patients had had normal C4 and C3 values, indicating that either C1q or C2 deficiency was possible. Thus, only 2 of 544 SLE families had definite or possible complement deficiency; however, 1 of 7 families in which all SLE patients had pediatric onset and 2 of 85 families with at least 1 pediatric-onset SLE patent had complete complement deficiency. SLE is found commonly among families with hereditary complement deficiency but the reverse is not true. Complete complement deficiency is rare among families with two or more SLE patients, but is concentrated among families with onset of SLE prior to age 18.

Ischaemic posterior circulation stroke in State of Qatar

BACKGROUND

Ischaemic stroke features may show regional differences. Posterior circulation stroke (PCS) is of special interest, as symptomatology, course and outcome are usually different and complex. No significant studies or registries have reported on the characteristics and outcomes of PCS in our region.

METHODS

We prospectively collected data of 116 patients with PCS admitted from 2005 through 2008 in the only stroke admitting hospital in Qatar. Demographics, risk factors, clinical signs/symptoms, pattern of presentation, aetiology, imaging features, complications and outcome at discharge and follow-up were recorded.

RESULTS

Mean age was 53 years with 25% aged < or = 45, 85% were males. Demographically 47% were Arabs and 51% of South-Asian origin. Mean duration from onset to presentation was 29 h. Major risk factors were obesity (66%) and hypertension (61%). Minimal or fluctuating symptoms were present in 64%, while 9% had maximal deficit at onset. Thirty nine per cent had lesions in proximal territory and 23% in multiple territories. Around 41% had no occlusion, 16% had vertebro-basilar, 16% vertebral, 8% basilar occlusion. Etiologically 53% patients had large artery disease, 16% small vessel disease, and 17% cardioembolism. Seventy per cent of patients were discharged home, while 10% expired. Modified Rankin score (mRS) at discharge was < or = 2 in 53% and > or = 4 in 13% patients. At 30-day follow-up, 68% had mRS of < or = 2. Ninety-day survival status showed 89% alive with mRS < or = 2 in 73%.

CONCLUSION

The aetiology and lesion topography of PCS in this heterogeneous population differs from the pattern observed in other populations.