The value of susceptibility-weighted imaging (SWI) in patients with non-neonatal hypoxic-ischemic encephalopathy

ObjectiveIn susceptibility-weighted imaging (SWI) in the normal brain, cortical veins appear hypointense due to paramagnetic properties of deoxy-hemoglobin. Global cerebral anoxia decreases cerebral oxygen metabolism, thereby increasing oxy-hemoglobin levels in cerebral veins. We hypothesized that a lower cerebral oxygen extraction fraction in comatose patients with non-neonatal hypoxic-ischemic encephalopathy (IHE) produces a pattern of global rarefied or pseudo-diminished cortical veins due to higher oxy-hemoglobin.Purpose(1) To investigate the topographic relationship between susceptibility effects in cortical veins and related diffusion restrictions on diffusion-weighted imaging (DWI) in patients with IHE. (2) To relate imaging findings to patterns of altered resting activity on surface EEG.MethodsTwenty-three IHE patients underwent MRI. EEG patterns were used to classify the depth of coma. Regional vs. global susceptibility changes on SWI and patterns of DWI restrictions were compared with the depth of coma.ResultsAll patients exhibited areas of restricted cortical diffusion and SWI abnormalities. The dominant DWI restrictions encompassed widespread areas along the precuneus, frontal and parietal association cortices and basal ganglia. For SWI, nineteen patients had generalized bi-hemispherical patterns, the EEG patterns correlated with coma grades III–V. Four patients had focal decreases of deoxy-hemoglobin following DWI restrictions; associated with normal EEGs.ConclusionFocal patterns of diamagnetic effects on SWI according to relative decreases in deoxy-hemoglobin due to reduced metabolic demand are associated with normal EEG in IHE patients. Global patterns indicated increased depth of coma and widespread cortical damage.Clinical relevanceThe results indicate a potential diagnostic value of SWI in patients with IHE.     

Feasibility and Exploratory Efficacy Evaluation of the Embrella Embolic Deflector System for the Prevention of Cerebral Emboli in Patients Undergoing Transcatheter Aortic Valve Replacement: The PROTAVI-C Pilot Study

ObjectivesThis study sought to determine the feasibility, safety, and exploratory efficacy of the Embrella Embolic Deflector (EED) system (Edwards Lifesciences, Irvine, California) in patients undergoing transcatheter aortic valve replacement (TAVR).BackgroundFew data exist on the value of using embolic protection devices during TAVR.MethodsThis pilot study included 52 patients who underwent transfemoral TAVR. The EED system was used in 41 patients, whereas 11 patients underwent TAVR without embolic protection (control group). Cerebral diffusion-weighted magnetic resonance imaging (DW-MRI) was performed at baseline and within 7 days and 30 days after TAVR.ResultsThe EED system was successfully deployed at the level of the aortic arch in all patients with no complications. The deployment of the EED system was associated with high-intensity transient signals (HITS) as evaluated by transcranial Doppler (median: 48 [interquartile range: 17 to 198] HITS), and a higher total number of HITS was observed in the EED group (p < 0.001 vs. control group). DW-MRI performed within 7 days after TAVR showed the presence of new ischemic lesions in all patients in both groups, with a median number of 7 (interquartile range: 3 to 13) lesions per patient. The use of the EED system was associated with a lower lesion volume compared with the control group (p = 0.003). All new cerebral lesions had disappeared on the DW-MRI performed at 30 days after TAVR. Two strokes unrelated to the EED system occurred 2 and 29 days after TAVR.ConclusionsThis study showed the feasibility and safety of using the EED system in TAVR procedures. The EED system did not prevent the occurrence of cerebral microemboli during TAVR or new transient ischemic lesions as evaluated by DW-MRI, but it was associated with a reduction in lesion volume. Further studies are warranted to determine the efficacy of using the EED system during TAVR procedures.     

The hinge region in androgen receptor control

The region between the DNA-binding domain and the ligand-binding domain of nuclear receptors is termed the hinge region. Although this flexible linker is poorly conserved, diverse functions have been ascribed to it. For the androgen receptor (AR), the hinge region and in particular the (629)RKLKKL(634) motif, plays a central role in controlling AR activity, not only because it acts as the main part of the nuclear translocation signal, but also because it regulates the transactivation potential and intranuclear mobility of the receptor. It is also a target site for acetylation, ubiquitylation and methylation. The interplay between these different modifications as well as the phosphorylation at serine 650 will be discussed here. The hinge also has an important function in AR binding to classical versus selective androgen response elements. In addition, the number of coactivators/corepressors that might act via interaction with the hinge region is still growing. The importance of the hinge region is further illustrated by the different somatic mutations described in patients with androgen insensitivity syndrome and prostate cancer. In conclusion, the hinge region serves as an integrator for signals coming from different pathways that provide feedback to the control of AR activity.     

Saccadic Palsy after Cardiac Surgery: Serial Neuroimaging Findings during a 6-Year Follow-Up

Background

Patients who develop horizontal and vertical saccadic palsy after cardiac surgery have rarely been described. Although most such patients exhibit distinct neurological deficits, their brain MRI findings are almost normal. In addition, functional neuroimaging of such patients has never been reported.

Case Report

A 43-year-old woman with dysarthria, dysphagia, and horizontal and vertical saccadic palsy after cardiac surgery was followed up for about 6 years; serial brain MRIs has been performed during this period, including susceptibility-weighted imaging (SWI) and [¹⁸F]-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET). Multiple microbleeds in the cerebral cortex, cerebellum, and brainstem, and glucose hypometabolism in the brainstem, cerebellum, and multiple cortical areas.

Conclusions

To the best of our knowledge, this is the first reported case of saccadic palsy after cardiac surgery with serial SWI and [¹⁸F]-FDG-PET performed to explore the possible cerebral lesions.     

Age-related iron deposition in the basal ganglia of controls and Alzheimer disease patients quantified using susceptibility weighted imaging

This study aimed to investigate age-related iron deposition changes in healthy subjects and Alzheimer disease patients using susceptibility weighted imaging. The study recruited 182 people, including 143 healthy volunteers and 39 Alzheimer disease patients. All underwent conventional magnetic resonance imaging and susceptibility weighted imaging sequences. The groups were divided according to age. Phase images were used to investigate iron deposition in the bilateral head of the caudate nucleus, globus pallidus and putamen, and the angle radian value was calculated. We hypothesized that age-related iron deposition changes may be different between Alzheimer disease patients and controls of the same age, and that susceptibility weighted imaging would be a more sensitive method of iron deposition quantification. The results revealed that iron deposition in the globus pallidus increased with age, up to 40 years. In the head of the caudate nucleus, iron deposition peaked at 60 years. There was a general increasing trend with age in the putamen, up to 50–70 years old. There was significant difference between the control and Alzheimer disease groups in the bilateral globus pallidus in both the 60–70 and 70–80 year old group comparisons. In conclusion, iron deposition increased with age in the globus pallidus, the head of the caudate nucleus and putamen, reaching a plateau at different ages. Furthermore, comparisons between the control and Alzheimer disease group revealed that iron deposition changes were more easily detected in the globus pallidus.