Impaired self-awareness after traumatic brain injury: a systematic review. Part 1: Assessment,clinical aspects and recovery

BackgroundImpaired self-awareness (ISA) has frequently been found to be both frequent and deleterious in patients with moderate to severe traumatic brain injury (TBI).ObjectivesThe present paper is the first of a two-part systematic review of ISA after traumatic brain injury (TBI), focusing on assessment methods, clinical aspects and recovery.MethodsFollowing the PRISMA guidelines, 95 articles meeting the inclusion criteria were included.ResultsISA occurs in 30% to 50% of patients with moderate to severe TBI, although it tends to improve with time. There is no one single gold-standard measure of ISA. Self-proxy discrepancy scores, with scales such as the Patient Competency Rating Scale or the Awareness Questionnaire, or a structured interview such as the Self Awareness of Deficits Interview, are the most frequently used assessment methods, with adequate psychometric properties. Scores on these different scales correlate only moderately with each other, which suggests that they may address different aspects of self-awareness. ISA mainly concerns cognitive and behavioral problems rather than physical or sensory impairments and may concern different areas of functioning, such as anticipatory, emergent or meta-cognitive awareness.ConclusionISA is a complex and multifaceted issue that should be systematically assessed in rehabilitation settings using a range of relatively well-validated tools. The consequences and predictors of ISA after TBI will be addressed in a companion paper.     

Effects of hemodynamic conditions and valve sizing on leaflet bending stress in self-expanding transcatheter aortic valve: An in vitro study

Transcatheter aortic valve (TAV) replacement has become a viable alternative to surgery for high and intermediate risk patients with severe aortic stenosis. This technology may extend to the younger and lower risk patients. In this population, long-term durability of the TAV is key. Increased leaflet mechanical stress is one of the main determinants of valve structural deterioration. This in vitro study aims at evaluating leaflet bending stress (LBS) in the self-expanding TAV for different valve sizes, stroke volumes (SV), and degrees of valve oversizing (OS). Three different sizes (23, 26, and 29 mm) of CoreValve (CV) were tested on a pulse duplicator in annulus size ranging from 17 to 26 mm. Leaflet bending stress and bending of the leaflet coaptation line in diastole pinwheeling index (PI) were measured using high-speed camera imaging (1000 images/s). For each given CV and annulus size, geometric orifice area (GOA) increased significantly with OS (P < .001) and SV (P = .001). LBS decreased with increasing prosthesis size and aortic annulus (AA) size while increasing with SV (P < .03). The largest value of peak LBS (3.79 MPa) was obtained with the CV 23 mm in AA of 17 mm (%OS = 35%), SV 90 mL and the smallest value (0.99 MPa) for the CV 29 mm in AA of 26 mm (%OS = 12%), SV 30 mL. On multivariable analysis, LBS increased independently with larger OS, smaller AA size and higher SV. The PI increased with decreasing AA size and increasing OS. Moderate valve OS, such as generally used for transcatheter aortic valve implantation, is associated with increased LBS during valve opening and closing, especially in small annuli. Hence, TAV OS may negatively impact long-term valve durability.     

Liver regeneration and recanalization time course following reversible portal vein embolization

BACKGROUND/AIMS: Permanent portal vein embolization (PVE) is a widely practised technique. The use of an absorbable material would be safer in clinical situations in which the embolized liver is not resected. We evaluated the efficiency of reversible PVE in terms of liver regeneration and analyzed the precise time course of portal recanalization. METHODS: Nine monkeys underwent PVE of the left and right anterior portal branches using powdered absorbable material. Repeated portograms were carried out until complete revascularization of the embolized liver. Hepatocyte proliferation rates were assessed by BrdU incorporation. Liver segment volumes were determined by CT scans performed before embolization, then 1month and 1year after embolization. RESULTS: Reversible PVE induced significant hepatocyte proliferation in the non-embolized segments (13.5+/-1.0%, 10.5+/-0.8% and 9.1+/-2.0% of cells on days 3, 5 and 7, respectively). One month after the embolization, the non-embolized liver volume had increased from 38.4+/-1.3% to 54.8+/-0.5% of total liver volume. Proximal and complete revascularization occurred 6-8 and 12-16days, respectively. CONCLUSIONS: Reversible PVE efficiently induces liver regeneration. The use of absorbable material avoids long-term liver scarring. Such material may be suitable for several clinical indications, including cell transplantation.     

Chronotropic incompetence to exercise separates low body weight from established anorexia nervosa

Chronotropic incompetence (CI), characterized by an attenuated heart rate (HR) response to exercise could participate to the limitation of exercise capacity in anorexia nervosa (AN). Therefore, we evaluated the role of cardiac sympathetic responsiveness in AN patients. In addition, the ambulatory value of autonomic control using spectral analysis of heart rate variability (HRV) was determined and correlated to maximal exercise performance. Twenty-two patients hospitalized for weight loss and suspicion of AN were included in the study. All performed a symptom-limited exercise test with measurement of gas exchange for chronotropic response to exercise evaluation. Holter ECG recordings allowed daytime and night-time spectral domain HRV analysis in order to evaluate the alteration of sympathetic control of HR in free-living conditions. CI defined as a failure to achieve 80% of heart rate reserve (%HRR) was observed in 13 (59%) patients (CI+). This group presented a higher body mass deficit than the group without CI (CI-; -35.1 +/- 8.7% versus -26.1 +/- 10.7%; P<0.05). Obviously, patients with a lower body mass index (BMI < 16 kg m(-2), n = 14) revealed a more severe limitation to maximal exercise with a lower peak HR, a lower peak Vo(2), and a lower maximal O(2) pulse (P<0.05). BMI was significantly correlated to peak Vo(2), maximal HR, and %HRR achieved at peak exercise. Daytime HRV parameters reflecting the sympathetic autonomic equilibrium (LF nu, LF/HF ratio) were significantly lower in CI+ patients. Blunted sympathetic response to maximal exercise is frequent and correlated to weight deficit. The present data suggest a major autonomic derangement in AN characterized by a cardiac sympathetic withdrawal.     

Comparative effects of adaptation on layers II–III and V–VI neurons in cat V1

V1 is fundamentally grouped into columns that descend from layers II–III to V–VI. Neurons inherent to visual cortex are capable of adapting to changes in the incoming stimuli that drive the cortical plasticity. A principle feature called orientation selectivity can be altered by the presentation of non‐optimal stimulus called ‘adapter’. When triggered, LGN cells impinge upon layer IV and further relay the information to deeper layers via layers II–III. Using different adaptation protocols, neuronal plasticity can be investigated. Superficial neurons in area V1 are well acknowledged to exhibit attraction and repulsion by shifting their tuning peaks when challenged by a non‐optimal stimulus called ‘adapter’. Layers V–VI neurons in spite of partnering layers II–III neurons in cortical computation have not been explored simultaneously toward adaptation. We believe that adaptation not only affects cells specific to a layer but modifies the entire column. In this study, through simultaneous multiunit recordings in anesthetized cats using a multichannel depth electrode, we show for the first time how layers V–VI neurons (1000–1200 μm) along with layers II–III neurons (300–500 μm) exhibit plasticity in response to adaptation. Our results demonstrate that superficial and deeper layer neurons react synonymously toward adapter by exhibiting similar behavioral properties. The neurons displayed similar amplitude of shift and maintained equivalent sharpness of Gaussian tuning peaks before and the following adaptation. It appears that a similar mechanism, belonging to all layers, is responsible for the analog outcome of the neurons’ experience with adapter.     

Flow through a defective mechanical heart valve: a steady flow analysis

Approximately 250,000 valve replacement operations occur annually around the world and more than two thirds of these operations use mechanical heart valves (MHV). These valves are subject to complications such: pannus and/or thrombus formation. Another potential complication is a malfunction in one of the valve leaflets. Although the occurrence of such malfunctions is low, they are life-threatening events that require emergency surgery. It is, therefore, important to develop parameters that will allow an early non-invasive diagnosis of such valve malfunction. In the present study, we performed numerical simulations of the flow through a defective mechanical valve under several flow and malfunction severity conditions. Our results show that the flow upstream and downstream of the defective valve is highly influenced by malfunction severity and this resulted in a misleading improvement in the correlation between simulated Doppler echocardiographic and catheter transvalvular pressure gradients. In this study, we were also able to propose and test two potential non-invasive parameters, using Doppler echocardiography and phase contrast magnetic resonance imaging, for an early detection of mechanical heart valve malfunction. Finally, we showed that valve malfunction has a significant impact on platelet activation and therefore on thrombus formation.     

Alteration of the QT rate dependence in anorexia nervosa

Myocardial repolarization has been evaluated in patients with anorexia nervosa (AN) with conflicting results. The authors postulated that dynamic alterations in QT interval adaptation could characterize these patients. This study compared QT dynamicity along RR intervals from 24-hour ECG data of patients with and without AN. Twenty-five patients (23 women) fulfilling the Diagnostic and Statistical Manual (DSM IV) criteria for AN were included in the study. All underwent 24-hour ECG Holter recordings, allowing QT and RR measurements, and heart rate variability (HRV) analysis in free-living conditions. A group of 25 sex- and age-matched healthy subjects served as controls. Compared with controls, AN patients presented with relative bradycardia, more particularly during night periods but neither mean QT nor corrected mean QT length (calculated using Bazett formula) over the 24 hours of monitoring differed. However, QT/RR slope was found significantly enhanced compared with normals (-2.00 +/- 0.53 vs - 1.42 +/- 0.40) (P = 0.006): QT length related to heart rate was found longer for a heart rate <55 beats/min in AN. Mean 24-hours QT length appears unaltered in AN in the absence of electrolytic disorders. However, the QT/RR relationship was enhanced reflecting the specific autonomic imbalance encountered in this population. The clinical implications of such findings need to be discussed since an equivalent enhancement of QT/RR slope has been described after myocardial infarction in patients presenting life-threatening ventricular arrhythmias.     

Age-related differences in hormonal and nutritional impact on lean anorexia nervosa bone turnover uncoupling

Introduction In anorexia nervosa (AN) patients osteoporosis occurs within a framework of multiple hormonal abnormalities as a result of bone turnover uncoupling, with decreased bone formation and increased bone resorption. The aim of study was to evaluate the hormonal and nutritional relationships with both of these bone remodeling compartments and their eventual modifications with age. Patients and measurements In a cohort of 115 AN patients (mean BMI:14.6 kg/m2) that included 60 mature adolescents (age: 15.5–20 years) and 55 adult women (age: 20–37 years) and in 28 age-matched controls (12 mature adolescents and 16 adults) we assessed: bone markers [serum osteocalcin, skeletal alkaline phosphatase (sALP), C-telopeptide of type I collagen (sCTX) and tartrate-resistant acid phosphatase type 5b (TRAP 5b)], nutritional markers [ body mass index (BMI, fat and lean mass), hormones (free tri-iodothyronine (T3), free T4, thyroid stimulating hormone (TSH), luteinizing hormone (LH), follicle stimulating hormone (FSH), 17 β estradiol, free testosterone index (FTI), dehydroepiandrosterone (DHEAS), insulin-like growth factor 1 (IGF-1), growth hormone (GH) and cortisol], plasma methoxyamines (metanephrine and normetanephrine) and calcium metabolism parameters [parathyroid hormone (PTH), Ca, vitamin D₃]. Results Osteocalcin reached similar low levels in both AN age subgroups. sCTX levels were found to be elevated in all AN subjects and higher in mature adolescents than in adult AN (11,567±895 vs. 8976±805 pmol/l, p<0.05). sALP was significantly lower only in mature adolescent AN patients, while there were no significant differences in the levels of TRAP 5b between AN patients and age-matched control groups. Osteocalcin correlated with sCTX in the control subjects (r=0.65) but not in the AN patients, suggesting the independent regulation of these markers in AN patients. Osteocalcin levels strongly correlated with freeT3, IGF-I, 17 β estradiol and cortisol, while sCTX correlated with IGF-I, GH and cortisol in both age subgroups of the AN patients. Other hormones or nutritional parameters displayed age-related correlations with bone markers, leading to different stepwise regression models for each age interval. In mature adolescent AN patients, up to 54% of the osteocalcin variance was due to BMI, cortisol and 17 β estradiol, while 54% of the sCTX variance was determined by GH. In adult subjects, freeT3 and IGF-I accounted for 64% of osteocalcin variance, while 65% of the sCTX variance was due to GH, FTI and methoxyamines. Conclusions We suggest a more complex mechanism of AN bone uncoupling that includes not only “classical” influence elements like cortisol, IGF-I, GH or 17 β estradiol but also freeT3, catecholamines and a “direct” hormone-independent impact of denutrition. Continuous changes of these influences with age should be considered within the therapeutic approach to AN bone loss.     

What do you mean by aortic valve area: geometric orifice area, effective orifice area, or gorlin area?

Aortic valve area can be measured by cardiac catheterization, Doppler echocardiography, or imaging planimetry to assess aortic stenosis severity. These diagnostic techniques provide the Gorlin area, the effective orifice area (EOA) and the geometric orifice area (GOA), respectively. The differences between these three parameters depend mainly on the valve inflow shape and cross-sectional area of the ascending aorta. Because the values obtained may differ noticeably in the same patient, they may lead to different estimations of stenosis severity depending on the measurement method used. It is therefore essential to be aware of the underlying fundamentals on which these parameters are based. The aim of this state-of-the-art report was to clarify these hemodynamic concepts and to underline their clinical implications. Because planimetry only provides GOA and does not characterize the flow property, this method should preferably not be used to assess stenosis severity. The most appropriate parameters for this purpose are the Gorlin area and the energy loss coefficient (E(L)Co), which corresponds to the EOA adjusted for aortic cross-sectional area. From a hemodynamic viewpoint, Doppler E(L)Co and Gorlin area both reflect the fluid energy loss induced by aortic stenosis, and describe better the increased overload imposed on the left ventricle. Although the Gorlin area and Doppler E(L)Co are equivalent, the latter parameter has the advantage of being measurable non-invasively using Doppler echocardiography.