A novel method of anatomical landmark selection for rib cage 3D reconstruction from biplanar radiography

Methods to reconstruct anatomical structures in 3D are gaining interest in medicine because they give access to quantitative information on the patient’s geometry. However, these methods are user-dependent and require a trained operator, which is time consuming and a source of error and unreliability. The aim of this work was to validate a novel method of landmark selection to perform the 3D reconstruction of the rib cage from biplanar calibrated radiographies. The method uses digital painting for digitization of anatomical landmarks (eight ribs midlines, posterior extrema, sternum) to build a first estimate of the 3D ribcage geometry. Twenty scoliotic patients were included (Cobb angle: 43° ± 11°) and their ribcage was reconstructed twice with the proposed method by four trained operators. Measurement reproducibility was similar to previously validated methods. Uncertainty (95% CI) was 2.3° for the rib hump measurement, 9.7 mm and 3.8 mm for maximal antero-posterior and lateral diameter, 395 cm3 for ribcage volume. The method was qualitatively considered more user-friendly than previous versions, although it still requires a trained operator, and it took approximately 2 minutes of manual digitization. The new method should facilitate diffusion of 3D quantitative analysis of ribcage in clinical routine

Recent advances in understanding hereditary spastic paraplegias and emerging therapies

International audienceHereditary spastic paraplegias (HSPs) are a group of rare, inherited, neurological diseases characterized by broad clinical and genetic heterogeneity. Lower-limb spasticity with first motoneuron involvement is the core symptom of all HSPs. As spasticity is a syndrome and not a disease, it develops on top of other neurological signs (ataxia, dystonia, and parkinsonism). Indeed, the definition of genes responsible for HSPs goes beyond the 79 identified SPG genes. In order to avoid making a catalog of the different genes involved in HSP in any way, we have chosen to focus on the HSP with cerebellar ataxias since this is a frequent association described for several genes. This overlap leads to an intermediary group of spastic ataxias which is actively genetically and clinically studied. The most striking example is SPG7, which is responsible for HSP or cerebellar ataxia or both. There are no specific therapies against HSPs, and there is a dearth of randomized trials in patients with HSP, especially on spasticity when it likely results from other mechanisms. Thus far, no gene-specific therapy has been developed for HSP, but emerging therapies in animal models and neurons derived from induced pluripotent stem cells are potential treatments for patients

Upper limb kinematics after Latissimus Dorsi transfer in children with brachial plexus birth palsy

Background: Brachial plexus birth palsy remains a frequent condition and one of its treatments is to transfer the Latissimus Dorsi tendon to the infraspinatus muscle. The aim of this study was to analyse, for the first time, the three-dimensional kinematic effects of this operation on the upper limb joints during the five Mallet tasks and their correlation with clinical parameters. Methods: Kinematic analysis was performed using an electromagnetic device. An Index of Improvement taking into account the angle in preop and postop, the reproducibility and the angle of a control group was developed. Three groups of patients were analysed: sixteen patients (mean: 10,5 years) for the reproducibility, thirty children (mean: 9,5 years) for the control group and ten patients (mean: 8 years 7 months) who were operated. Findings: The humerothoracic and glenohumeral external rotations improved during the external rotation, the neck and the abduction tasks and worsened during the spine task. The glenohumeral external rotation worsened during the mouth task. The Humerothoracic abduction improved during the abduction and the neck tasks. The elbow flexion improved for the neck task. Differences were observed between patients and correlations were obtained between the Index of Improvement and clinical parameters. Interpretation: Using kinematics allows to better analyse the evolution of joint angles after the latissimus dorsi transfer. The Index of Improvement allows to quickly analyse the effect of the operation for each angle and each patient. This effect depends on clinical parameters

Ultrasound shearwave elastography to characterize muscles of healthy and cerebral palsy children

International audienceShear wave elastography (SWE) is an ultrasound technique to obtain soft tissue mechanical properties. The aim of this study was to establish the reliability of SWE in young children, define reference data on healthy ones and compare the shear modulus of healthy and spastic muscles fromcerebral palsy (CP). The reproducibility is evaluated: at rest, on 7 children without any musculoskeletal pathology by 3 different operators, on 2 muscles: biceps brachii long head and medial gastrocnemius. The comparison study was made, on the same 2 muscles, at rest and under passive stretching, with a control group (29 healthy children), a spastic group (spastic muscles of 16 children from CP) and a non‑spastic group (non‑spastic muscles of 14 children from CP). The intra‑operator reliability and inter‑operator reliability, in terms of standard deviation, were 0.6 kPa (11.2% coefficient of variation (CV)) and 0.8 kPa (14.9% CV) for the biceps, respectively, and 0.4 kPa (11.5% CV) and 0.5 kPa (13.8% CV) for the gastrocnemius. At rest, no significant difference was found. Under passive stretching, the non‑spastic CP biceps were significantly stiffer than the control ones (p = 0.033). Spastic gastrocnemius had a higher shear modulus than in the control muscles (p = 0.0003) or the non‑spastic CP muscles (p = 0.017). CP stretched medial gastrocnemius presented an abnormally high shear moduli for 50% ofpatients

The Myelic Limited Dorsal Malformation: Prenatal Ultrasonographic Characteristics of an Intermediate Form of Dysraphism

Objectives: The aim of the study was to report a subtype of dysraphism designated as myelic limited dorsal malformation (MyeLDM) and to describe its characteristics at prenatal ultrasound (US). Methods: It was a retrospective study from 2014 to 2020 based on second-line US evaluation of patients referred to our institution for myelomeningocele (MMC). Magnetic resonance imaging and acetylcholine esterase evaluation in the amniotic fluid were also offered. Major and minor criteria for open and closed dysraphism were defined and recorded for each patient. Patients were included as MyeLDM when both criteria of closed and open dysraphism were observed in the same fetus. Correlations were obtained with the postpartum data. Results: Twenty patients fulfilled the inclusion criteria, some of them being very close to MMC, others very close to limited dorsal myeloschisis (LDM), and others lying in between. There were 13 live-born neonates and 7 terminations of pregnancy. Correlations between prenatal and postpartum data were overall very good. Conclusion: Our series describe the ultrasonographic characteristics of an intermediate type of dysraphism and suggest that there is a continuum between MMC and LDM with numerous possibilities of hybrid forms (MyeLDM) sharing characteristics of both open and closed dysraphisms

Baseline Clinical and Blood Biomarkers in Patients With Preataxic and Early-Stage Disease Spinocerebellar Ataxia 1 and 3.

BACKGROUND AND OBJECTIVES: In spinocerebellar ataxia, ataxia onset can be preceded by mild clinical manifestation, cerebellar and/or brainstem alterations, or biomarker modifications. READISCA is a prospective, longitudinal observational study of patients with spinocerebellar ataxia type 1 (SCA1) and 3 (SCA3) to provide essential markers for therapeutic interventions. We looked for clinical, imaging, or biological markers that are present at an early stage of the disease. METHODS: We enrolled carriers of a pathologic ATXN1 or ATXN3 expansion and controls from 18 US and 2 European ataxia referral centers. Clinical, cognitive, quantitative motor, neuropsychological measures and plasma neurofilament light chain (NfL) measurements were compared between expansion carriers with and without ataxia and controls. RESULTS: We enrolled 200 participants: 45 carriers of a pathologic ATXN1 expansion (31 patients with ataxia [median Scale for the Assessment and Rating of Ataxia: 9; 7-10] and 14 expansion carriers without ataxia [1; 0-2]) and 116 carriers of a pathologic ATXN3 expansion (80 patients with ataxia [7; 6-9] and 36 expansion carriers without ataxia [1; 0-2]). In addition, we enrolled 39 controls who did not carry a pathologic expansion in ATXN1 or ATXN3. Plasma NfL levels were significantly higher in expansion carriers without ataxia than controls, despite similar mean age (controls: 5.7 pg/mL, SCA1: 18.0 pg/mL [p < 0.0001], SCA3: 19.8 pg/mL [p < 0.0001]). Expansion carriers without ataxia differed from controls by significantly more upper motor signs (SCA1 p = 0.0003, SCA3 p = 0.003) and by the presence of sensor impairment and diplopia in SCA3 (p = 0.0448 and 0.0445, respectively). Functional scales, fatigue and depression scores, swallowing difficulties, and cognitive impairment were worse in expansion carriers with ataxia than those without ataxia. Ataxic SCA3 participants showed extrapyramidal signs, urinary dysfunction, and lower motor neuron signs significantly more often than expansion carriers without ataxia. DISCUSSION: READISCA showed the feasibility of harmonized data acquisition in a multinational network. NfL alterations, early sensory ataxia, and corticospinal signs were quantifiable between preataxic participants and controls. Patients with ataxia differed in many parameters from controls and expansion carriers without ataxia, with a graded increase of abnormal measures from control to preataxic to ataxic cohorts. TRIAL REGISTRATION INFORMATION: ClinicalTrials.gov NCT03487367

Sensory and corticospinal signs before ataxia onset in SCA1 and SCA3: the READISCA study

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Baseline Clinical and Blood Biomarker in Patients With Preataxic and Early-Stage Disease Spinocerebellar Ataxia 1 and 3

International audienceBackground and Objective: In spinocerebellar ataxia, ataxia onset can be preceded by mild clinical manifestation, cerebellar and/or brainstem alterations or biomarkers modifications. READISCA is a prospective, longitudinal observational study of patients with spinocerebellar ataxias type 1 and 3 to provide essential markers for therapeutic interventions. We looked for clinical, imaging or biological markers that are present at an early-stage of the disease. Methods: We enrolled carriers of a pathological ATXN1 or ATXN3 expansion and controls from 18 US and two European ataxia referral centers. Clinical, cognitive, quantitative motor, neuropsychological measures and plasma neurofilament light chain (NfL) measurements were compared between mutation carriers with and without ataxia and controls. Results: We enrolled 200 participants: 45 carriers of a pathological ATXN1 expansion (31 patients with ataxia (median SARA: 9 [7;10]), 14 mutation carriers without ataxia (1 [0;2])) and 116 carriers of a pathological ATXN3 expansion (80 patients with ataxia (7 [6;9]), 36 mutation carriers without ataxia (1 [0;2])). In addition, we enrolled 39 controls who did not carry a pathological expansion in ATXN1 or ATXN3 . Plasma NfL levels were significantly higher in mutation carriers without ataxia than controls, despite similar mean age (controls: 5.7 pg/mL, SCA1: 18.0 pg/mL (P <0.0001), SCA3: 19.8 pg/mL (P<0.0001). Mutation carriers without ataxia differed from controls by significantly more upper motor signs (SCA1 P=0.0003, SCA3 P=0.003) and by the presence of sensor impairment and diplopia in SCA3 (P=0.0448, and 0.0445 respectively). Functional scales, fatigue and depression scores, swallowing difficulties, and cognitive impairment were worse in mutation carriers with ataxia than those without ataxia. Ataxic SCA3 subjects showed extrapyramidal signs, urinary dysfunction and lower motor neuron signs significantly more often than mutation carriers without ataxia. Discussion: READISCA showed the feasibility of harmonized data acquisition in a multi-national network. NfL alterations, early sensory ataxia and corticospinal signs were quantifiable between preataxic participants and controls. Patients with ataxia differed in many parameters from controls and mutation carriers without ataxia, with a graded increase of abnormal measures from control to preataxic to ataxic cohorts

The mitochondrial seryl-tRNA synthetase SARS2 modifies onset in spastic paraplegia type 4

International audienceHereditary spastic paraplegia type 4 is extremely variable in age at onset; the same variant can cause onset at birth or in the eighth decade. We recently discovered that missense variants in SPAST, which influences microtubule dynamics, are associated with earlier onset and more severe disease than truncating variants, but even within the early and late-onset groups there remained significant differences in onset. Given the rarity of the condition, we adapted an extreme phenotype approach to identify genetic modifiers of onset. Methods: We performed a genome-wide association study on 134 patients bearing truncating pathogenic variants in SPAST, divided into early-and late-onset groups (aged ≤15 and ≥45 years, respectively). A replication cohort of 419 included patients carrying either truncating or missense variants. Finally, age at onset was analyzed in the merged cohort (N = 553). Results: We found 1 signal associated with earlier age at onset (rs10775533, P = 8.73E-6) in 2 independent cohorts and in the merged cohort (N = 553, Mantel-Cox test, P < .0001). Western blotting in lymphocytes of 20 patients showed that this locus tends to upregulate SARS2 expression in earlier-onset patients. Conclusion: SARS2 overexpression lowers the age of onset in hereditary spastic paraplegia type 4. Lowering SARS2 or improving mitochondrial function could thus present viable approaches to therapy