Marc Schlamann

Silent and Apparent Cerebral Ischemia After Percutaneous Transfemoral Aortic Valve Implantation A Diffusion-Weighted Magnetic Resonance Imaging Study

Background— The risk of stroke after transfemoral aortic valve implantation (TAVI) due to dislodgement and subsequent embolization of debris from aortic arch atheroma or from the calcified valve itself ranges between 2% and 10%. The rate of clinically silent cerebral ischemia is unknown but may be even higher. Methods and Results— Thirty-two patients who underwent TAVI with the use of a balloon-expandable (n=22) or self-expandable (n=10) stent valve prosthesis were included in this descriptive study and compared with a historical control group of 21 patients undergoing open surgical aortic valve replacement. Periprocedural apparent and silent cerebral ischemia was assessed by neurological testing and serial cerebral diffusion-weighted magnetic resonance imaging at baseline, at 3.4 (2.5 to 4.4) days after the procedure, and at 3 months. TAVI was successful in all patients. After the procedure, new foci of restricted diffusion on cerebral diffusion-weighted magnetic resonance imaging were found in 27 of 32 TAVI patients (84%) and were more frequent than after open surgery (10 of 21 patients [48%]; P=0.011). These lesions were usually multiple (1 to 19 per patient) and dispersed in both hemispheres in a pattern suggesting cerebral embolization. Volumes of these lesions were significantly smaller after TAVI than after surgery (77 [59 to 94] versus 224 [111 to 338] mm3; P<0.001). There were neither measurable impairments of neurocognitive function nor apparent neurological events during the in-hospital period among TAVI patients, but there was 1 stroke (5%) in the surgical patient group. On 3-month follow-up diffusion-weighted magnetic resonance imaging, there were no new foci of restricted diffusion, and there was no residual signal change associated with the majority (80%) of the foci detected in the periprocedural period. Conclusions— Clinically silent new foci of restricted diffusion on cerebral magnetic resonance imaging were detected in almost all patients (84%) undergoing TAVI. Although typically multiple, these foci were not associated with apparent neurological events or measurable deterioration of neurocognitive function during 3-month follow-up. Further work needs to be directed to determine the clinical significance of these findings in a larger patient population.

Cerebral Embolization During Transcatheter Aortic Valve Implantation A Transcranial Doppler Study

Background— Transcatheter aortic valve implantation (TAVI) is associated with a higher risk of neurological events for both the transfemoral and transapical approach than surgical valve replacement. Cerebral magnetic resonance imaging has revealed more new, albeit clinically silent lesions from procedural embolization, yet the main source and predominant procedural step of emboli remain unclear. Methods and Results— Eighty-three patients underwent transfemoral (Medtronic CoreValve [MCVTF], n=32; Edwards Sapien [ESTF], n=26) and transapical (ESTA: n=25) TAVI. Serial transcranial Doppler examinations before, during, and 3 months after TAVI were used to identify high-intensity transient signals (HITS) as a surrogate for microembolization. Procedural HITS were detected in all patients, predominantly during manipulation of the calcified aortic valve while stent valves were being positioned and implanted. The balloon-expandable ES prosthesis caused significantly more HITS (mean [95% CI]) during positioning (ESTF, 259.9 [184.8–334.9]; ESTA, 206.1[162.5–249.7]; MCVTF, 78.5 [25.3–131.6]; P<0.001) and the self-expandable MCV prosthesis during implantation (MCVTF, 397.1 [302.1–492.2]; ESTF, 88.2 [70.2–106.3]; ESTA, 110.7 [82.0–139.3]; P<0.001). Overall, there were no significant differences between transfemoral and transapical TAVI or between the MCV and ES prostheses. No HITS were detected at baseline or 3-month follow-up. There was 1 major procedural stroke that resulted in death and 1 minor procedural stroke with full recovery at 3-month follow-up in the MCV group. Conclusions— Procedural HITS were detected by transcranial Doppler in all patients. Although no difference was observed between the transfemoral and the transapical approach with the balloon-expandable ES stent valve, transfemoral TAVI with the self-expandable MCV prosthesis resulted in the greatest number of HITS, predominantly during implantation.

First clinical study on ultra-high-field MR imaging in patients with multiple sclerosis: comparison of 1.5T and 7T.

BACKGROUND AND PURPOSE: Higher magnetic field strengths and continuous improvement of high-resolution imaging in multiple sclerosis (MS) are expected to provide unique in-vivo and non-invasive insights in pathogenesis and clinical monitoring. The purpose of this study was to investigate the potential of high-resolution imaging of MS lesions in vivo comparing 7T with conventional 1.5T. MATERIALS AND METHODS: Twelve consecutive patients with clinically definite MS were scanned on a 7T whole-body scanner and on a 1.5T Avanto. The 1.5T and 7T imaging protocol consisted of high-resolution axial proton density (PD) + T2-weighted turbo spin-echo and T2*-weighted gradient-echo (GRE), and sagittal T1-weighted 3D magnetization-prepared rapid acquisition of gradient echo. RESULTS: The sequence parameters at 7T had to be modified because of specific absorption rate (SAR) restrictions while keeping contrast parameters equivalent to 1.5T. White matter lesions were better detected and delineated from adjacent structures at 7T compared with 1.5T. There were 42% of the patients who showed additional lesions at 7T: there were 97 white matter lesions detected on 1.5T versus 126 lesions at 7T, an increase of 23%. The perivascular migration of MS lesions was well visualized on T2*-weighted GRE sequences. In larger lesions (10 mm), a multilayer structure was revealed on T2*-weighted GRE not seen at 1.5T. Because of the higher resolution, it was possible to differentiate between juxtacortical white matter lesions and cortical lesions. There were 44% of the subcortical lesions depicted at 7T that showed cortical involvement. CONCLUSIONS: Ultra-high-field imaging of patients with MS at 7T was well tolerated and provided better visualization of MS lesions in the gray matter and demonstrated structural abnormalities within the MS lesions themselves more effectively.

Mechanical recanalization in basilar artery occlusion: The ENDOSTROKE study

A study was undertaken to evaluate clinical and procedural factors associated with outcome and recanalization in endovascular stroke treatment (EVT) of basilar artery (BA) occlusion.

ORIGINAL RESEARCH—INTERSEX AND GENDER IDENTITY DISORDERS: Specific Cerebral Activation due to Visual Erotic Stimuli in Male-to-Female Transsexuals Compared with Male and Female Controls: An fMRI Study

INTRODUCTION Transsexuals harbor the strong feeling of having been born to the wrong sex. There is a continuing controversial discussion of whether or not transsexualism has a biological representation. Differences between males and females in terms of functional imaging during erotic stimuli have been previously described, revealing gender-specific results. AIM Therefore, we postulated that male-to-female (MTF) transsexuals may show specific cerebral activation differing from their biological gender. MAIN OUTCOME MEASURE Cerebral activation patterns during viewing of erotic film excerpts in functional magnetic resonance imaging (fMRI). METHODS Twelve male and 12 female heterosexual volunteers and 12 MTF transsexuals before any treatment viewed erotic film excerpts during fMRI. Additionally, subjective rating of sexual arousal was assessed. Statistics were performed using the Statistical Parametric Mapping software. RESULTS Significantly enhanced activation for men compared with women was revealed in brain areas involved in erotic processing, i.e., the thalamus, the amygdala, and the orbitofrontal and insular cortex, whereas no specific activation for women was found. When comparing MTF transsexuals with male volunteers, activation patterns similar to female volunteers being compared with male volunteers were revealed. Sexual arousal was assessed using standard rating scales and did not differ significantly for the three groups. CONCLUSIONS We revealed a cerebral activation pattern in MTF transsexuals compared with male controls similar to female controls compared with male controls during viewing of erotic stimuli, indicating a tendency of female-like cerebral processing in transsexualism.

The human hippocampus at 7 T--in vivo MRI.

The human hippocampus plays a central role in various neuropsychiatric disorders, such as temporal lobe epilepsy (TLE), Alzheimers dementia, mild cognitive impairment, and schizophrenia. Its volume, morphology, inner structure, and function are of scientific and clinical interest. Magnetic resonance (MR) imaging is a widely employed tool in neuroradiological workup regarding changes in brain anatomy, (sub‐) volumes, and cerebral function including the hippocampus. Gain in intrinsic MR signal provided by higher field strength scanners and concomitant improvements in spatial resolution seem highly valuable. An examination protocol permitting complete, high‐resolution imaging of the human hippocampus at 7 T was implemented. Coronal proton density, T2, T2*, and fluid‐attenuated inversion recovery contrasts were acquired as well as an isotropic 3D magnetization‐prepared rapid acquisition gradient‐echo (500 μm isotropic voxel dimension, noninterpolated). Observance of energy deposition restrictions within acceptable scan times remained challenging in the acquisition of thin, spin‐echo‐based sections. At the higher resolution enabled by 7 T, demarcation of the hippocampus and some internal features including gray/white matter differentiation and depiction of the hippocampal mantle becomes much more viable when compared with 1.5 T; thus, in the future, this imaging technology might help in the diagnosis of subtle hippocampal changes.

Cognitive Outcomes Three Years After Coronary Artery Bypass Surgery: Relation to Diffusion-Weighted Magnetic Resonance Imaging

BACKGROUND Cognitive decline is well recognized early after coronary artery bypass graft surgery (CABG), but controversy exists regarding the degree and duration of these changes. We investigated the course of cognitive performance during 3 years after surgery and determined whether ischemic brain injury detected by diffusion-weighted magnetic resonance imaging was related to cognitive decline. METHODS Thirty-nine patients undergoing on-pump CABG completed preoperative neuropsychologic examination and were followed up prospectively at discharge, 3 months, and 3 years after surgery. Cognitive performance was assessed with a battery of 11 standardized psychometric tests assessing 7 cognitive domains. Cognitive outcome was analyzed by determining (1) mean changes in within-patient scores over time (identifying cognitive functions with decline), and (2) the incidence of cognitive deficit for each individual (identifying patients with decline). Objective evidence of acute cerebral ischemia was obtained by diffusion-weighted magnetic resonance imaging. Prospectively collected data were used to identify predictors of cognitive deficits. RESULTS From baseline to discharge, cognitive test scores significantly declined in 7 measures. Most tests improved by 3 months. Between 3 months and 3 years, late decline was observed in 2 measures with persistent deterioration in 1 measure (verbal memory) relative to baseline. Postoperative cognitive deficits (drop of > or = 1 SD in scores on > or = 3 tests) were observed in 56% of patients at discharge, 23% at 3 months and 31% at 3 years. On postoperative diffusion-weighted magnetic resonance imaging, there were new ischemic cerebral lesions in 51% of patients. The presence of cognitive deficit at discharge was a significant univariate predictor of late cognitive decline (p = 0.025). A relation between the presence of new diffusion-weighted magnetic resonance imaging detected lesions and cognitive decline, however, was not found. CONCLUSIONS Longitudinal cognitive performance of patients with CABG showed a two-stage course with early improvement followed by later decline. Long-term cognitive deficit was predicted by early cognitive decline, but not by ischemic brain lesions on magnetic resonance imaging.

Structural and functional MRI abnormalities of cerebellar cortex and nuclei in SCA3, SCA6 and Friedreich’s ataxia

Spinocerebellar ataxia type 3, spinocerebellar ataxia type 6 and Friedreichs ataxia are common hereditary ataxias. Different patterns of atrophy of the cerebellar cortex are well known. Data on cerebellar nuclei are sparse. Whereas cerebellar nuclei have long been thought to be preserved in spinocerebellar ataxia type 6, histology shows marked atrophy of the nuclei in Friedreichs ataxia and spinocerebellar ataxia type 3. In the present study susceptibility weighted imaging was used to assess atrophy of the cerebellar nuclei in patients with spinocerebellar ataxia type 6 (n = 12, age range 41-76 years, five female), Friedreichs ataxia (n = 12, age range 21-55 years, seven female), spinocerebellar ataxia type 3 (n = 10, age range 34-67 years, three female), and age- and gender-matched controls (total n = 23, age range 22-75 years, 10 female). T1-weighted magnetic resonance images were used to calculate the volume of the cerebellum. In addition, ultra-high field functional magnetic resonance imaging was performed with optimized normalization methods to assess function of the cerebellar cortex and nuclei during simple hand movements. As expected, the volume of the cerebellum was markedly reduced in spinocerebellar ataxia type 6, preserved in Friedreichs ataxia, and mildy reduced in spinocerebellar ataxia type 3. The volume of the cerebellar nuclei was reduced in the three patient groups compared to matched controls (P-values < 0.05; two-sample t-tests). Atrophy of the cerebellar nuclei was most pronounced in spinocerebellar ataxia type 6. On a functional level, hand-movement-related cerebellar activation was altered in all three disorders. Within the cerebellar cortex, functional magnetic resonance imaging signal was significantly reduced in spinocerebellar ataxia type 6 and Friedreichs ataxia compared to matched controls (P-values < 0.001, bootstrap-corrected cluster-size threshold; two-sample t-tests). The difference missed significance in spinocerebellar ataxia type 3. Within the cerebellar nuclei, reductions were significant when comparing spinocerebellar ataxia type 6 and Friedreichs ataxia to matched controls (P < 0.01, bootstrap-corrected cluster-size threshold; two-sample t-tests). Susceptibility weighted imaging allowed depiction of atrophy of the cerebellar nuclei in patients with Friedreichs ataxia and spinocerebellar ataxia type 3. In spinocerebellar ataxia type 6, pathology was not restricted to the cerebellar cortex but also involved the cerebellar nuclei. Functional magnetic resonance imaging data, on the other hand, revealed that pathology in Friedreichs ataxia and spinocerebellar ataxia type 3 is not restricted to the cerebellar nuclei. There was functional involvement of the cerebellar cortex despite no or little structural changes.

Neural circuitry of abdominal pain‐related fear learning and reinstatement in irritable bowel syndrome

Altered pain anticipation likely contributes to disturbed central pain processing in chronic pain conditions like irritable bowel syndrome (IBS), but the learning processes shaping the expectation of pain remain poorly understood. We assessed the neural circuitry mediating the formation, extinction, and reactivation of abdominal pain‐related memories in IBS patients compared to healthy controls (HC) in a differential fear conditioning paradigm.

Posterior Reversible Encephalopathy Syndrome: The Spectrum of MR Imaging Patterns

AimThe aim of this study was to describe lesion patterns, distribution, and evolution in posterior reversible encephalopathy syndrome (PRES) in a larger single-center population.MethodsScans and follow-up, if available, of 50 patients with PRES between 2002 and 2011 were reviewed retrospectively. Lesion patterns, extent, and signal intensity changes were identified and graded on fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted images. Hemorrhagic changes were identified on T2* or susceptibility-weighted images, and gadolinium enhancement on T1-weighted images was identified if available.ResultsThe most frequently affected regions on FLAIR were the frontal lobes in 54 %, occipital lobes in 34.3 %, and parietal lobes in 31.0 % of cases, thus 65.3 % in the posterior regions. Temporal lobes were affected in 10.6 %, the cerebellum in 6.5 %, and basal ganglia in 1.6 %. Division into vascular supply showed involvement in the anterior circulation in 66.5 % and in the posterior circulation in 33.5 % of cases. On diffusion-weighted imaging (DWI), vasogenic edema was observed in 6.9 %, cytotoxic edema in 9.1 %, and both in 2 % of cases. In 31.9 %, there was shine through, and in 15.9 %, there was shine through as well as cytotoxic or vasogenic edema. Topologic distribution on DWI showed affection of the frontal lobes in 43.5 %, occipital lobes in 25.8 %, parietal lobes in 17.7 %, temporal lobes in 11.3 %, and cerebellum in 1.6 %. T2* or susceptibility-weighted images showed spot-like hemosiderin accumulation in 17.2 % of cases. In 23.1 %, enhancement was seen. Follow-up magnetic resonance imaging showed complete resolution in 66.6 % of patients.ConclusionThe spectrum of imaging findings in PRES is wide. Almost always subcortical and cortical structures are involved. Although posterior changes are prominent in this syndrome, frontal involvement is more frequent than posterior on FLAIR imaging and DWI. On DWI, mixed patterns are not uncommon. Reversibility generally takes place independent of DWI pathology. Hypertension was not a prognostic factor.