Frequency domain near-infrared spectroscopy technique in the assessment of brain oxygenation: a validation study in live subjects and cadavers

BACKGROUND: Studies with continuous wave near infrared spectroscopy (CW-NIRS) have shown little difference in brain oxygenation of dead compared to live subjects. We determined brain oxyhemoglobin (OHb) and deoxyhemoglobin (HHb) concentrations in healthy volunteers and cadavers using frequency domain near infrared spectroscopy (FD-NIRS). METHODS: Regional OHb and HHb, brain oxygen saturation (SO2), and total hemoglobin (tHb) were determined. Nine patients who died in the hospital were evaluated by FD-NIRS in the morgue 7-96 h after death was confirmed. Ten volunteers served as a control group. RESULTS: Absolute concentrations of brain tissue OHb and HHb were 24.9 +/- 9.1 uM and 13.8 +/- 32 uM, respectively, in live subjects. In dead subjects, OHb was 1.3 +/- 2.1 uM and HHb was 30.8 +/- 14.4 uM (both P < 0.05 compared to live). OHb showed a 90% decrease within 7h of death. There was a significant trend for a continued decrease in OHb from 7 to 96 h. CONCLUSION: OHb decreased and HHb increased in dead patients compared to live volunteers. Depletion of OHb primarily occurred within 7 h of death but continued gradually over 96 h. FD-NIRS was a novel technique for determining OHb and HHb changes following death.     

Endovascular treatment of tentorial dural arteriovenous fistulae

Tentorial dural arteriovenous fistula (DAVF) is a rare vascular disease, which accounts for less than 4% of all cases of intracranial DAVF. Because of the high risk of intracranial hemorrhage, patients with tentorial DAVF need aggressive treatment. Management approaches are still controversial, and endovascular treatment has emerged as an effective alternative. In the current work, we describe our experience with the endovascular approach in the treatment of these deep and complex DAVF of the tentorium. Eight patients were treated between January 2006 and July 2009. Six patients (75%) presented with intracranial hemorrhage related to the DAVF rupture. Four patients (50%) had subarachnoid bleeding and two had intraparenchymal hematoma. Endovascular treatment was performed via the transarterial route alone in five cases (62.5%), by the transvenous approach in two cases (25.0%) and in a combined procedure using both arterial and venous routes in one patient (12.5%). Complete obliteration of the fistula was achieved in all cases. The outcome at 15 months was favorable (modified Rankin scale 0-3) in seven (87.5%) patients. Complete cure of the lesion was confirmed in these cases. This paper reports on the effectiveness of endovascular treatment in tentorial DAVF management. The choice of the venous versus the arterial approach is determined by regarding different anatomical dispositions.     

Varying proliferative and clonogenic potential in NRAS‐mutated congenital melanocytic nevi according to size

Congenital melanocytic nevi (CMN) are benign proliferations that may be associated with various consequences depending on their size. They are characterized by a specific molecular signature, namely a postzygotic somatic NRAS or BRAF mutation. We have recently reported that large CMN (lCMN), which are classically associated with an increased melanoma risk, harbour cell subpopulations with specific clonogenic and tumorigenic potential. We wished to ascertain whether cells displaying similar properties persisted postnatally in medium CMN (mCMN). Eighteen medium M1, nine large and one giant NRAS‐mutated CMN were prospectively included in the study. Subpopulations of mCMN cells expressed stem cell/progenitor lineage markers such as Sox10, nestin and Oct4, as was the case in lCMN. Nevertheless, conversely to lCMN, mCMN cells with clonogenic properties were rarer. In vitro, approximatively one in 1500 cells isolated from fresh mCMN formed colonies that could be passaged. In vivo, mCMN seemed to harbour cells with less proliferative potential than the larger lesions as lCMN biopsies displayed a threefold expansion compared to mCMN when xenografted in Rag2^?/? mice. Thus, our data revealed variations in clonogenicity and tumorigenic properties in NRAS‐mutated CMN according to size.     

Imaging in multiple sclerosis: A new spin on lesions

This article evaluates the most relevant state‐of‐the‐art magnetic resonance (MR) techniques that are clinically available to investigate multiple sclerosis (MS). The presence of hypo‐ and hyperintense lesions on T1‐ and T2‐weighted magnetic resonance imaging (MRI) sequences in white matter (WM) is a common finding that is occasionally a diagnostic challenge for the radiologist. The technical requirements and how they may help to understand, classify or follow‐up these pathologies are briefly summarized. The gold standard for MS diagnosis is pathological correlation. Yet due to limited availability of biopsy and autopsy material, there is a high demand for imaging as a diagnostic as well as prognostic indicator. With the progress in MRI during the last decade, MRI now plays a leading role in the diagnosis and follow‐up of MS. A number of correlative pathological and MR studies have helped to define pathological substrates of MS in focal lesions and normal appearing white matter (NAWM). Vascular spaces mimicking MS lesions have been minimized by the enhanced differentiation of WM and grey (GM) matter parenchyma. The aim of this article is to enhance the current understanding of histopathology and radiological characteristics of MS lesions in space and time.     

Indigenous Arabs are descendants of the earliest split from ancient Eurasian populations

An open question in the history of human migration is the identity of the earliest Eurasian populations that have left contemporary descendants. The Arabian Peninsula was the initial site of the out-of-Africa migrations that occurred between 125,000 and 60,000 yr ago, leading to the hypothesis that the first Eurasian populations were established on the Peninsula and that contemporary indigenous Arabs are direct descendants of these ancient peoples. To assess this hypothesis, we sequenced the entire genomes of 104 unrelated natives of the Arabian Peninsula at high coverage, including 56 of indigenous Arab ancestry. The indigenous Arab genomes defined a cluster distinct from other ancestral groups, and these genomes showed clear hallmarks of an ancient out-of-Africa bottleneck. Similar to other Middle Eastern populations, the indigenous Arabs had higher levels of Neanderthal admixture compared to Africans but had lower levels than Europeans and Asians. These levels of Neanderthal admixture are consistent with an early divergence of Arab ancestors after the out-of-Africa bottleneck but before the major Neanderthal admixture events in Europe and other regions of Eurasia. When compared to worldwide populations sampled in the 1000 Genomes Project, although the indigenous Arabs had a signal of admixture with Europeans, they clustered in a basal, outgroup position to all 1000 Genomes non-Africans when considering pairwise similarity across the entire genome. These results place indigenous Arabs as the most distant relatives of all other contemporary non-Africans and identify these people as direct descendants of the first Eurasian populations established by the out-of-Africa migrations.All humans can trace their ancestry back to Africa (Cann et al. 1987), where the ancestors of anatomically modern humans first diverged from primates (Patterson et al. 2006), and then from archaic humans (Prüfer et al. 2014). Humans began leaving Africa through a number of coastal routes, where estimates suggest these “out-of-Africa” migrations reached the Arabian Peninsula as early as 125,000 yr ago (Armitage et al. 2011) and as late as 60,000 yr ago (Henn et al. 2012). After entering the Arabian Peninsula, human ancestors entered South Asia and spread to Australia (Rasmussen et al. 2011), Europe, and eventually, the Americas. The individuals in these migrations were the most direct ancestors of ancient non-African peoples, and they established the contemporary non-African populations recognized today (Cavalli-Sforza and Feldman 2003).The relationship between contemporary Arab populations and these ancient human migrations is an open question (Lazaridis et al. 2014; Shriner et al. 2014). Given that the Arabian Peninsula was an initial site of egress from Africa, one hypothesis is that the original out-of-Africa migrations established ancient populations on the peninsula that were direct ancestors of contemporary Arab populations (Lazaridis et al. 2014). These people would therefore be direct descendants of the earliest split in the lineages that established Eurasian and other contemporary non-African populations (Armitage et al. 2011; Rasmussen et al. 2011; Henn et al. 2012; Lazaridis et al. 2014; Shriner et al. 2014). If this hypothesis is correct, we would expect that there are contemporary, indigenous Arabs who are the most distant relatives of other Eurasians. To assess this hypothesis, we carried out deep-coverage genome sequencing of 104 unrelated natives of the Arabian Peninsula who are citizens of the nation of Qatar (Supplemental Fig. 1), including 56 of indigenous Bedouin ancestry who are the best representatives of autochthonous Arabs, and compared these genomes to contemporary genomes of Africa, Asia, Europe, and the Americas (The 1000 Genomes Project Consortium 2012; Lazaridis et al. 2014).     

Hypoxic Brain Tissue following Subarachnoid Hemorrhage

Background: Subarachnoid hemorrhage can lead to cerebral ischemia and irreversible brain injury. The purpose of this study was to determine whether subarachnoid hemorrhage produces changes in brain tissue oxygen pressure, carbon dioxide pressure, or pH during surgery for cerebral aneurysm clipping.

Methods: After institutional review board approval and patient consent, 30 patients undergoing craniotomy for cerebral aneurysm clipping were studied, 15 without and 15 with subarachnoid hemorrhage. Patients with subarachnoid hemorrhage were prospectively separated into groups with modest (Fisher grade 1 or 2; n = 8) and severe bleeds (Fisher grade 3; n = 7). After a craniotomy, a probe was inserted into cortex tissue supplied by the artery associated with the aneurysm. Baseline measures were made in the presence of a 4% end-tidal desflurane level. The end-tidal desflurane level was increased to 9% before clipping of the aneurysm, and a second tissue measurement was made.

Results: The median time of surgery after subarachnoid hemorrhage was 2 days, ranging from 1 to 13 days. During baseline anesthesia, brain tissue oxygen pressure was 17 +/- 9 mmHg (mean +/- SD) in control patients, 13 +/- 9 mmHg in those with Fisher grade 1 or 2 hemorrhage, and 7 +/- 6 mmHg in those with Fisher grade 3 hemorrhage (P < 0.05 compared with control). Brain tissue pH was 7.10 +/- 0.10 in control patients, 7.14 +/- 0.13 in those with Fisher grade 1 or 2 hemorrhage, and 6.95 +/- 0.18 in those with with Fisher grade 3 hemorrhage (P < 0.05). At a 9% end-tidal desflurane level, brain tissue oxygen pressure increased to 19 +/- 9 mmHg and brain tissue pH increased to 7.11 +/- 0.11 in patients with Fisher grade 3 hemorrhage (P < 0.05 for both increases).     

X-ray-free protocol for pectus deformities based on magnetic resonance imaging and a low-cost portable three-dimensional scanning device: a preliminary study

 Open in a separate windowOBJECTIVESTo compare a standard protocol using chest computed tomography (CT) to a non-irradiant protocol involving a low-cost portable 3D scanner and magnetic resonance imaging (MRI) for all pectus deformities based on the Haller index (HI).METHODSFrom April 2019 to March 2020, all children treated for pectus excavatum or carinatum at our institution were evaluated by chest CT, 3D scanning (iPad with Structure Sensor and Captevia—Rodin4D) and MRI. The main objectives were to compare the HI determined by CT or MRI to a derived index evaluated with 3D scanning, the external Haller index (EHI). The secondary objectives were to assess the inter-rater variability and the concordance between CT and MRI for the HI and the correction index.RESULTSEleven patients were evaluated. We identified a strong correlation between the HI with MRI and the EHI (Pearson correlation coefficient = 0.900; P < 0.001), with a strong concordance between a radiologist and a non-radiologist using intra-class correlation for the HI with MRI (intra-class correlation coefficient = 0.995; [0.983; 0.999]) and the EHI (intra-class correlation coefficient = 0.978; [0.823; 0.995]). We also identified a marked correlation between the HI with CT and the EHI (Pearson coefficient = 0.855; P = 0.002), with a strong inter-rater concordance (intra-class correlation coefficient = 0.975; [0.901; 0.993]), a reliable concordance between CT and MRI for the HI and the correction index (Pearson coefficient = 0.886; P = 0.033).CONCLUSIONSNon-irradiant pectus deformity assessment is possible in clinical practice, replacing CT with MRI and 3D scanning as a possible readily-accessible monitoring tool.