Phase-contrast magnetic resonance imaging of intracranial and extracranial blood flow in carotid near-occlusion.

PURPOSE: Compare extracranial internal carotid artery flow rates and intracranial collateral use between conventional ≥ 50% carotid stenosis and carotid near-occlusion, and between symptomatic and asymptomatic carotid near-occlusion. METHODS: We included patients with ≥ 50% carotid stenosis. Degree of stenosis was diagnosed on CTA. Mean blood flow rates were assessed with four-dimensional phase-contrast MRI. RESULTS: We included 110 patients of which 83% were symptomatic, and 38% had near-occlusion. Near-occlusions had lower mean internal carotid artery flow (70 ml/min) than conventional ≥ 50% stenoses (203 ml/min, P < .001). Definite use of ≥ 1 collateral was found in 83% (35/42) of near-occlusions and 10% (7/68) of conventional stenoses (P < .001). However, there were no differences in total cerebral blood flow (514 ml/min vs. 519 ml/min, P = .78) or ipsilateral hemispheric blood flow (234 vs. 227 ml/min, P = .52), between near-occlusions and conventional ≥ 50% stenoses, based on phase-contrast MRI flow rates. There were no differences in total cerebral or hemispheric blood flow, or collateral use, between symptomatic and asymptomatic near-occlusions. CONCLUSION: Near-occlusions have lower internal carotid artery flow rates and more collateral use, but similar total cerebral blood flow and hemispheric blood flow, compared to conventional ≥ 50% carotid stenosis.

Relationship Between Objective and Subjective Markers of Muscle Recovery in Professional Handball Players.

PURPOSE: To evaluate the relationship between items of the Short Recovery and Stress Scale (SRSS) related to physical stress and recovery and the biomarker creatine kinase (CK) in professional handball. METHODS: CK and SRSS items (physical performance capability, overall recovery, muscular stress, and overall stress) were assessed in an observational study of 16 adult male professional handball players from a team in the highest German league during the 2019-20 preseason. Their preseason training schedule included several microcycles, each consisting of 3 consecutive days of intense training followed by a rest day. On 5 of these rest days, when players were classified as nonrested, and the 5 immediately following days, when players were classified as rested, players completed the SRSS between 8:00 and 9:00 AM, followed by blood sampling. Correlations between SRSS items were performed using Kendall τ. The relationship between each SRSS item and CK levels over time was examined using a mixed-effects model with a random intercept. RESULTS: CK levels and SRSS stress items were significantly higher and SRSS recovery items were significantly lower in nonrested players. SRSS items were significantly positively or negatively correlated (all items: P < .001) and showed a significant effect indicating lower CK levels in rested players (all items: P ≤ .001; ηp2=.1-.32). CONCLUSIONS: The investigated SRSS items may be a viable option for assessing muscle recovery in adult male professional handball players in a cost-effective and noninvasive manner. They can be used as a single monitoring tool or as part of a multimodal approach.

High risk of early recurrent stroke in patients with near-occlusion with full collapse of the internal carotid artery.

We aimed to validate the prognostic ability and assess interrater reliability of a recently suggested measurement-based definition of near-occlusion with full collapse (distal ICA diameter ≤ 2.0 mm and/or ICA ratio ≤ 0.42). 118 consecutive patients with symptomatic near-occlusion were prospectively included and assessed on computed tomography angiography by 2 blinded observers, 26 (22%) had full collapse. At 2 days after presenting event, the risk of preoperative stroke was 3% for without full collapse and 16% for with full collapse (p = 0.01). At 28 days, this risk was 16% for without full collapse and 22% for with full collapse (p = 0.22). Interrater reliability was perfect (kappa 1.0). Thus, near-occlusion with full collapse should be defined as distal ICA ≤ 2.0 mm and/or ICA ratio ≤ 0.42 in order to detect cases with very high risk of early stroke recurrence.

Diagnostic separation of conventional ⩾50% carotid stenosis and near-occlusion with phase-contrast MRI.

INTRODUCTION: The aim of this study was to assess sensitivity, specificity and interrater reliability of phase-contrast MRI (PC-MRI) for diagnosing carotid near-occlusion. PATIENTS AND METHODS: Prospective cross-sectional study conducted between 2018 and 2021. We included participants with suspected 50%-100% carotid stenosis on at least one side, all were examined with CT angiography (CTA) and PC-MRI and both ICAs were analyzed. Degree of stenosis on CTA was the reference test. PC-MRI-based blood flow rates in extracranial ICA and intracranial cerebral arteries were assessed. ICA-cerebral blood flow (CBF) ratio was defined as ICA divided by sum of both ICAs and Basilar artery. RESULTS: We included 136 participants. The ICAs were 102 < 50% stenosis, 88 conventional ⩾50% stenosis (31 with ⩾70%), 49 near-occlusion, 12 occlusions, 20 unclear cause of small distal ICA on CTA and one excluded. For separation of near-occlusion and conventional stenoses, ICA flow rate and ICA-CBF ratio had the highest area under the curve (AUC; 0.98-0.99) for near-occlusion. ICA-CBF ratio ⩽0.225 was 90% (45/49) sensitive and 99% (188/190) specific for near-occlusion. Inter-rater reliability for this threshold was excellent (kappa 0.98). Specificity was 94% (29/31) for cases with ⩾70% stenosis. PC-MRI had modest performance for separating <50% and conventional ⩾50% stenosis (highest AUC 0.74), and eight (16%) of near-occlusions were not distinguishable from occlusion (no visible flow). CONCLUSION: ICA-CBF ratio ⩽0.225 on PC-MRI is an accurate and reliable method to separate conventional ⩾50% stenosis and near-occlusion that is feasible for routine use. PC-MRI should be considered further as a potential standard method for near-occlusion detection, to be used side-by-side with established modalities as PC-MRI cannot separate other degrees of stenosis.

Risk of Stroke Recurrence After Intravenous Thrombolysis in Patients with Symptomatic Carotid Stenosis.

OBJECTIVE: To assess if intravenous thrombolysis (IVT) affects the risk of recurrent preoperative cerebrovascular events before carotid surgery or stenting in patients with symptomatic ≥ 50% carotid stenosis. METHODS: Three cohorts of symptomatic ≥ 50% carotid stenosis patients were merged. To make the control group relevant, we excluded patients not presenting with stroke on the day of symptom onset. The risk of preoperative cerebrovascular events up to 30 days was compared between the IVT-treated and non-IVT-treated. RESULTS: In total, 316 patients were included, 64 (20%) treated with IVT. Those treated with IVT had similar risk of recurrent ipsilateral ischemic stroke or retinal artery occlusion (12% at day 7, 12% at day 30) as those not treated (9% at day 7, 15% at day 30; adjusted HR 0.9, 95% CI 0.4-2.2). There was a tendency (p = 0.09) towards time-dependency in the data where the recurrence risk was higher in IVT-treated at day 0 (6% in IVT-treated, 1% in non-IVT-treated, OR 5.5, 95% CI 1.2-25.4, p = 0.03). This was not significant when adjusting for co-factors (adjusted OR 4.4, 95% CI 0.9-21.8, p = 0.07) and was offset by a later risk decrease, with no remaining risk difference between IVT-treated and non-IVT-treated at day 7. CONCLUSIONS: Intravenous thrombolysis treatment does not seem to affect the risk of recurrent ipsilateral ischemic stroke in patients with symptomatic ≥50% carotid stenosis: The risk is high in both IVT-treated and non-IVT-treated. However, there might be a risk increase on the day of IVT treatment that is offset by a risk decrease during the first week.

[Considerations when handling common acute intracranial vascular anomalies]. / Akuta vaskulära neurokirurgiska tillstånd kräver snabb hantering.

Conditions involving intracranial vascular anomalies are increasingly diagnosed, not least incidentally, with the increasing availability of neuroradiological investigations. Acute deterioration and development of symptoms due to a vascular condition could require neurosurgical intervention depending on the nature of the condition and status of the patient. On the other hand, asymptomatic patients with incidental findings require careful consideration and risk assessment when deciding on whether or not to treat the condition, and if so, how. In this review article we provide a summary of some of the most common neurosurgical vascular conditions and outline management considerations in both the acute and elective setting.

Biochemical Monitoring of Muscle Recovery in Elite Handball Using an Individualized Approach.

PURPOSE: To evaluate the classification performance of a new method to individualize reference ranges for biomarkers of muscle recovery in elite handball. METHODS: In a longitudinal observational study, creatine kinase (CK) and urea levels were assessed in 16 male elite handball players during the 2019-20 preseason. Blood samples were collected at prespecified time points when players were considered either recovered or nonrecovered. Initially, linear mixed-effects models were calculated, as outlined in the study design, to examine the effect of recovery status on CK and urea levels. Finally, a fixed-effect model was calculated for urea based on the law of parsimony. Individualized reference ranges were calculated using a recently published algorithm. To investigate whether the individualized approach resulted in a more accurate classification of recovery status (recovered or nonrecovered), it was compared with a group-based approach derived from the same data set, utilizing predefined error rates. RESULTS: Linear mixed-effects models showed a large effect of recovery status on CK (P < .001, d = 3.49) and a small effect on urea (P = .018, d = 0.382). In contrast to CK (P = .017), urea had no significant interindividual variation. Hence, individualization was examined only for CK. The numerical decrease in both CK error rates by the individualized approach was significant for the test-pass error rate (P = .0196, ϕ = .19). CONCLUSIONS: Our findings underscore the critical role of CK for monitoring in team sports such as handball. The observed improvement in CK error rates suggests a promising opportunity to individualize biochemical monitoring, although further studies encompassing larger sample sizes are warranted.

[Monitoring and load management in team handball]. / Monitoring und Belastungssteuerung im Handball.

BACKGROUND: The monitoring of athletes has become a focus in elite-level team sports and research in recent years. The goal is to optimise load management for maximising performance. Due to the considerable amount of data gathered during monitoring in team sports, the trend is towards integrating different monitoring methods in a software-based tool. In addition, decision-support systems are used in order to enable coaches to make quick decisions to control further burdens. This article is intended to give an overview of the large number of monitoring methods used in contact team sports, to consider their test quality criteria and to check a useful application of monitoring methods for team handball, taking into account the sports-specific requirements. METHODS: PubMed-based review of the literature. Narrative review focusing on current data from the years 2010 to 2019. RESULTS: Demands on athletes in elite team handball vary depending on the playing position. Therefore, individualised load control is necessary. Monitoring methods with proven validity and reliability should ideally be used in a multivariate approach to represent the various aspects of external and internal load, recovery and fatigue, well-being and readiness. It is important to know the meaningful change for each athlete while using a monitoring method. This circumstance necessitates an individualised approach for each parameter. There are not many studies on the use of monitoring methods in team handball, neither in the amateur field nor in an elite sports environment. Nevertheless, based on evidence from other contact team sports, a recommendation for a combined use of monitoring methods can be given. Burden, time and cost/benefit should always be considered. CONCLUSION: There is a considerable need for research regarding the use of athlete monitoring in team handball. The combination of monitoring methods proposed in this article can be used as a framework for studies with handball players in an elite sports environment in order to implement an increasingly handball-specific monitoring concept in the future.

Switching the Structure Type upon Ag Substitution: Synthesis and Crystal as well as Electronic Structures of Li12AgGe4.

Li-rich compounds of metals and semimetals are interesting candidates for anode materials for rechargeable batteries. The investigation of the Li-rich part of the Li-Ag-Ge phase diagram led to the discovery of the new compound Li12AgGe4, which represents the Li-richest phase in the ternary phase system. The phase-pure compound is synthesized by high-temperature reaction of Li with stoichiometric amounts of premelted reguli of Ag and Ge. The structure was determined by single-crystal X-ray diffraction. Li12AgGe4 crystallizes in the Li13Si4 structure type in the space group Pbam (no. 55) with lattice parameters of a = 8.0420(2) Å, b = 15.1061(4) Å, and c = 4.4867(1) Å and exhibits the unique Zintl anion [AgGe2](7-)-iso(valence) electronic to the CO2 molecule-and Ge2 dumbbells. Li12AgGe4 adopts the atom packing of the lighter homologue Li13Si4 and not that of Li13Ge4 by the selective substitution of one out of seven Li positions by Ag. The calculation of the electronic structure indicates metallic property and the presence of strong covalent bonds between Ag and Ge in the linear triatomic Ge-Ag-Ge unit as well as π character between the Ge atoms of the dumbbells. The Ag-Ge bond order of the linear AgGe2 unit reaches its maximum at EF of Li12AgGe4 with full occupancy of all atomic positions (in contrast to the related Li12Ag1-xSi4), indicating that the formation of covalent Ag-Ge bonds is the driving force for the formation of the structure type.

Fully and partially Li-stuffed diamond polytypes with Ag-Ge structures: Li2AgGe and Li2.53AgGe2.

In view of the search for and understanding of new materials for energy storage, the Li-Ag-Ge phase diagram has been investigated. High-temperature syntheses of Li with reguli of premelted Ag and Ge led to the two new compounds Li(2)AgGe and Li(2.80-x)AgGe(2) (x = 0.27). The compounds were characterized by single-crystal X-ray diffraction. Both compounds show diamond-polytype-like polyanionic substructures with tetrahedrally coordinated Ag and Ge atoms. The Li ions are located in the channels provided by the network. The compound Li(2)AgGe crystallizes in the space group R3̅m (No. 166) with lattice parameters of a = 4.4424(6) Å and c = 42.7104(6) Å. All atomic positions are fully occupied and ordered. Li(2.80-x)AgGe(2) crystallizes in the space group I4(1)/a (No. 88) with lattice parameters of a = 9.7606(2) Å and c = 18.4399(8) Å. The Ge substructure consists of unique (1)(∞)[Ge(10)] chains that are interconnected by Ag atoms to build a three-dimensional network. In the channels of this diamond-like network, not all of the possible positions are occupied by Li ions. Li atoms in the neighborhood of the vacancies show considerably enlarged displacement vectors. The occurrence of the vacancy is traced back to short Li-Li distances in the case of the occupation of the vacancy with Li. Both compounds are not electron-precise Zintl phases. The density of states, band structure, and crystal orbital Hamilton population analyses of Li(2.80-x)AgGe(2 )reveal metallic properties, whereas a full occupation of all Li sites leads to an electron-precise Zintl compound within a rigid-band model. Li(2)AgGe reveals metallic character in the ab plane and is a semiconductor with a small band gap along the c direction.

Tetrahedral framework structures: polymorphic phase transition with reorientation of hexagonal helical channels in the Zintl compound Na2ZnSn5 and its relation to Na5Zn(2+x)Sn(10-x).

Two modifications of the new Zintl compound Na2ZnSn5 were synthesized by direct reactions of the elements. hP-Na2ZnSn5, which is metastable under standard conditions, is obtained by fast cooling of a melt of stoichiometric composition. Slow cooling of such a melt or tempering of hP-Na2ZnSn5 (e.g., at 300 °C) leads to the thermodynamically stable tI-Na2ZnSn5. Both phases show an open framework structure of four-bonded Zn and Sn atoms exhibiting hexagonal helical channels in which the Na atoms are situated with disorder. Whereas the Zn-Sn network of hP-Na2ZnSn5 is analogous to known Tr-Sn networks (Tr = Ga, In), tI-Na2ZnSn5 features a closely related novel framework with a different channel structure. In the structure model for hP-Na2ZnSn5 there is only one, Zn/Sn mixed occupied, site for the framework atoms, whereas Zn and Sn are fully ordered on three sites in the case of tI-Na2ZnSn5. The phase transition from hP-Na2ZnSn5 to tI-Na2ZnSn5 was studied using high-temperature powder and single-crystal X-ray diffraction methods. Na2ZnSn5 is stable up to about 350 °C and does not melt congruently but decomposes to form Na5Zn(2+x)Sn(10-x). DFT band structure calculations (TB-LMTO-ASA) were performed with ordered model structures which were deduced from a conceivable pathway for the interconversion of the two polymorphic structures of Na2ZnSn5. A band gap at the Fermi level, as expected for a Zintl phase, is found for the ordered structure of tI-Na2ZnSn5. On the basis of an analysis of the relationship between the network structures of the Sn-rich Na-Zn-Sn phases, a general perspective for novel open framework structures with exclusively four-bonded atoms is given.

Soluble Zintl phases A14ZnGe16 (A = K, Rb) featuring [(η3-Ge4)Zn(η2-Ge4)]6- and [Ge4]4- clusters and the isolation of [(MesCu)2(η3,η3-Ge4)]4-: the missing link in the solution chemistry of tetrahedral group 14 element Zintl clusters.

The number of Zintl phases containing polyhedral clusters of tetrel elements that are accessible for chemical reactions of the main-group element clusters is rather limited. The synthesis and structural characterization of two novel ternary intermetallic phases A(14)ZnGe(16) (A = K, Rb) are presented, and their chemical reactivity is investigated. The compounds can be rationalized as Zintl phases with 14 alkali metal cations A(+) (A = K, Rb), two tetrahedral [Ge(4)](4-) Zintl anions, and one anionic heterometallic [(Ge(4))Zn(Ge(4))](6-) cluster per formula unit. The Zn-Ge cluster comprises two (Ge(4)) tetrahedra which are linked by a Zn atom, with one (Ge(4)) tetrahedron coordinating with a triangular face (η(3)) and the other one with an edge (η(2)). [(η(3)-Ge(4))Zn(η(2)-Ge(4))](6-) is a new isomer of the [(Ge(4))Zn(Ge(4))](6-) anion in Cs(6)ZnGe(8). The phases dissolve in liquid ammonia and thus represent rare examples of soluble Zintl compounds with deltahedral units of group 14 element atoms. Compounds with tetrahedral [E(4)](4-) species have previously been isolated from solution for E = Si, Sn, and Pb, and the current investigation provides the "missing link" for E = Ge. Reaction of an ammonia solution of K(14)ZnGe(16) with MesCu (Mes = 2,4,6-(CH(3))(3)C(6)H(2)) in the presence of [18]-crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane) yielded crystals of the salt [K([18]-crown-6)](2)K(2)[(MesCu)(2)Ge(4)](NH(3))(7.5) with the polyanion [(MesCu)(2)Ge(4)](4-). This MesCu-stabilized tetrahedral [Ge(4)](4-) cluster also completes the series of [(MesCu)(2)Si(4-x)Ge(x)](4-) clusters, which have previously been isolated from solution for x = 0 and 0.7, as the end member with x = 4. The electronic structures of [(Ge(4))Zn(Ge(4))](6-) and [(MesCu)(2)Ge(4)](4-) were investigated in terms of a molecular orbital description and analyses of the electron localization functions. The results are compared with band structure calculations for the A(14)ZnGe(16) phases (A = K, Rb).