Border Zone Maybe Correlated with Radiation Necrosis After Radiosurgery in Metastatic Brain Tumor.

BACKGROUND: Radiation necrosis (RN) after stereotactic radiosurgery (SRS) in brain metastases has been extensively evaluated, and RN is correlated with various risk factors. However, no study comprehensively analyzed the correlation between RN and the border zones of the brain that are vulnerable to ischemia. We hypothesized that patients with tumors in the border zone are at high risk of RN. Hence, the current study aimed to assess the correlation between border zone lesions and RN, with consideration of other predetermined factors. METHODS: This retrospective study included 117 patients with 290 lesions who underwent Gamma Knife SRS. Radiological and clinical analyses were performed to identify factors possibly correlated with RN. Notably, the lesion location was classified into 2 groups (border zone and nonborder zone) based on the blood supply. RESULTS: In total, 22 (18.8%) patients with 22 (7.5%) lesions developed RN. Univariate analysis revealed a significant correlation between RN and external border zone lesions, second course of SRS administered at the same site of the previous SRS, prescribed dose, and tumor volume. Multivariate analysis showed that border zone lesions, second course of SRS at the same site of the previous SRS, and tumor volume were significantly correlated with RN. CONCLUSIONS: Patients with tumors in the border zone are at high risk of RN. The potential risks of RN can be attributed hypothetically to hypoperfusion. Hence, the association between RN and border zone lesions seems reasonable.

Diagnostic performance of synthetic relaxometry for predicting neurodevelopmental outcomes in premature infants: a feasibility study.

OBJECTIVES: To investigate the predictability of synthetic relaxometry for neurodevelopmental outcomes in premature infants and to evaluate whether a combination of relaxation times with clinical variables or qualitative MRI abnormalities improves the predictive performance. METHODS: This retrospective study included 33 premature infants scanned with synthetic MRI near or at term equivalent age. Based on neurodevelopmental assessments at 18-24 months of corrected age, infants were classified into two groups (no/mild disability [n = 23] vs. moderate/severe disability [n = 10]). Clinical and MRI characteristics associated with moderate/severe disability were explored, and combined models incorporating independent predictors were established. Ultimately, the predictability of relaxation times, clinical variables, MRI findings, and a combination of the two were evaluated and compared. The models were internally validated using bootstrap resampling. RESULTS: Prolonged T1-frontal/parietal and T2-parietal periventricular white matter (PVWM), moderate-to-severe white matter abnormality, and bronchopulmonary dysplasia were significantly associated with moderate/severe disability. The overall predictive performance of each T1-frontal/-parietal PVWM model was comparable to that of individual MRI finding and clinical models (AUC = 0.71 and 0.76 vs. 0.73 vs. 0.83, respectively; p > 0.27). The combination of clinical variables and T1-parietal PVWM achieved an AUC of 0.94, sensitivity of 90%, and specificity of 91.3%, outperforming the clinical model alone (p = 0.049). The combination of MRI finding and T1-frontal PVWM yielded AUC of 0.86, marginally outperforming the MRI finding model (p = 0.09). Bootstrap resampling showed that the models were valid. CONCLUSIONS: It is feasible to predict adverse outcomes in premature infants by using early synthetic relaxometry. Combining relaxation time with clinical variables or MRI finding improved prediction. CLINICAL RELEVANCE STATEMENT: Synthetic relaxometry performed during the neonatal period may serve as a biomarker for predicting adverse neurodevelopmental outcomes in premature infants. KEY POINTS: • Synthetic relaxometry based on T1 relaxation time of parietal periventricular white matter showed acceptable performance in predicting adverse outcome with an AUC of 0.76 and an accuracy of 78.8%. • The combination of relaxation time with clinical variables and/or structural MRI abnormalities improved predictive performance of adverse outcomes. • Synthetic relaxometry performed during the neonatal period helps predict adverse neurodevelopmental outcome in premature infants.

Juxtacortical White Matter Hypointensity on T2*Gradient Echo Image in Vanishing White Matter Disease: A Case Report.

BACKGROUND Vanishing white matter disease (VWMD) - also known as childhood ataxia with central nervous system hypomyelination - is one of the most commonly inherited white matter diseases in children. Notably, a course of chronic progressive disease with episodes of rapid and major stress-induced neurological deterioration, such as fever and minor head trauma, is a typical clinical feature of VWMD. The combination of clinical features with specific magnetic resonance imaging findings, including diffuse and extensive white matter lesions with rarefaction or cystic destruction, could recommend a genetic diagnosis. However, VWMD is phenotypically diverse and can affect individuals of all ages. CASE REPORT A 29-year-old female patient presented with recent aggravation in gait disturbance. She had progressive movement disorder, with symptoms ranging from hand tremors to upper- and lower-extremity weakness, for 5 years. Whole-exome sequencing was performed to confirm the diagnosis of VWMD, and it revealed a mutation in homozygous eIF2B2 gene. The temporal evolution of VWMD observed in the patient for 17 years (from the age of 12 to 29 years) indicated an increased extent of T2 white matter hyperintensity in the cerebrum into the cerebellum and an increased amount of dark signal intensities in the globus pallidus and dentate nucleus. Moreover, a T2*-weighted imaging (WI) scan revealed diffuse, linear, and symmetrical hypointensity along the juxtacortical white matter on the magnification view. CONCLUSIONS This is the case report about rare and unusual finding of diffuse linear juxtacortical white matter hypointensity on T2*-WI scan as a potential radiographic marker for adult-onset VWMD.

Arrested Pneumatization of the Sphenoid Sinus.

The sphenoid bone is a complex structure in terms of its embryological origin. At birth, the sphenoid sinus is nonpneumatized. Arrested pneumatization of the sphenoid sinus is considered a normal anatomic variant but may be mistaken for disease in imaging studies. We report 2 cases of arrested pneumatization of the sphenoid sinus, a normal variant commonly misdiagnosed as a serious disease of the skull base. A 29-year-old man with a complaint of dizziness visited a local clinic for assessment. Computed tomography (CT) of the paranasal sinuses (PNS) showed a noneroding, nonexpansile, and nonhomogenous lesion in the sphenoid bone. Magnetic resonance imaging (MRI) of the brain revealed a high-signal lesion on both T1-weighted and T2-weighted images. Given these typical findings in the CT of PNS and MRI of the brain, the lesion was diagnosed as arrested pneumatization of the sphenoid sinus. In the second case, a 60-year-old woman with a complaint of headache visited a local clinic for assessment. CT of PNS showed a fibro-osseous lesion (with features of sclerosis and osteolysis) in the skull base. Brain MRI revealed a low-signal lesion on a T1-weighted image containing a high-signal intensity around the sphenoid bone, thereby suggesting internal fat contents. A precise interpretation of CT of PNS and brain MRI is essential to distinguish arrested pneumatization of the sphenoid sinus and to help establish a differential diagnosis and avoid needless biopsy.

Hepatic encephalopathy on magnetic resonance imaging and its uncertain differential diagnoses: a narrative review.

Hepatic encephalopathy (HE) is a severe neuropsychiatric abnormality in patients with either acute or chronic liver failure. Typical brain magnetic resonance imaging findings of HE are bilateral basal ganglia high signal intensities due to manganese deposition in chronic liver disease and hyperintensity in T2, fluid-attenuated inversion recovery, or diffusion-weighted imaging (DWI) with hemispheric white matter changes including the corticospinal tract. Low values on apparent diffusion coefficient mapping of the affected area on DWI, indicating cytotoxic edema, can be observed in acute HE. However, neuropsychological impairment in HE ranges from mild deficits in psychomotor abilities affecting quality of life to stupor or coma with higher grades of hepatic dysfunction. In particular, the long-lasting compensatory mechanisms for the altered metabolism in chronic liver disease make HE imaging results variable. Therefore, the clinical relevance of imaging findings is uncertain and differentiating HE from other metabolic diseases can be difficult. The recent introduction of concepts such as "acute-on-chronic liver failure (ACLF)," a new clinical entity, has led to a change in the clinical view of HE. Accordingly, there is a need to establish a corresponding concept in the field of neuroimaging diagnosis. Herein, we review HE from a historical and etiological perspective to increase understanding of brain imaging and help establish an imaging approach for advanced new concepts such as ACLF. The purpose of this manuscript is to provide an understanding of HE by reviewing neuroimaging findings based on pathological and clinical concepts of HE, thereby assisting in neuroimaging interpretation.

Distinct cerebral cortical perfusion patterns in idiopathic normal-pressure hydrocephalus.

The aims of the study are to evaluate idiopathic normal-pressure hydrocephalus (INPH)-related cerebral blood flow (CBF) abnormalities and to investigate their relation to cortical thickness in INPH patients. We investigated cortical CBF utilizing surface-based early-phase 18 F-florbetaben (E-FBB) PET analysis in two groups: INPH patients and healthy controls. All 39 INPH patients and 20 healthy controls were imaged with MRI, including three-dimensional volumetric images, for automated surface-based cortical thickness analysis across the entire brain. A subgroup with 37 participants (22 INPH patients and 15 healthy controls) that also underwent 18 F-fluorodeoxyglucose (FDG) PET imaging was further analyzed. Compared with age- and gender-matched healthy controls, INPH patients showed statistically significant hyperperfusion in the high convexity of the frontal and parietal cortical regions. Importantly, within the INPH group, increased perfusion correlated with cortical thickening in these regions. Additionally, significant hypoperfusion mainly in the ventrolateral frontal cortex, supramarginal gyrus, and temporal cortical regions was observed in the INPH group relative to the control group. However, this hypoperfusion was not associated with cortical thinning. A subgroup analysis of participants that also underwent FDG PET imaging showed that increased (or decreased) cerebral perfusion was associated with increased (or decreased) glucose metabolism in INPH. A distinctive regional relationship between cerebral cortical perfusion and cortical thickness was shown in INPH patients. Our findings suggest distinct pathophysiologic mechanisms of hyperperfusion and hypoperfusion in INPH patients.

Clinical adaptation of synthetic MRI-based whole brain volume segmentation in children at 3 T: comparison with modified SPM segmentation methods.

PURPOSE: To validate the use of synthetic magnetic resonance imaging (SyMRI) volumetry by comparing with child-optimized SPM 12 volumetry in 3 T pediatric neuroimaging. METHODS: In total, 106 children aged 4.7-18.7 years who underwent both synthetic and 3D T1-weighted imaging and had no abnormal imaging/neurologic findings were included for the SyMRI vs. SPM T1-only segmentation (SPM T1). Forty of the 106 children who underwent an additional 3D T2-weighted imaging were included for the SyMRI vs. SPM multispectral segmentation (SPM multi). SPM segmentation using an age-appropriate atlas and inverse-transforming template-space intracranial mask was compared with SyMRI segmentation. Volume differences between SyMRI and SPM T1 were plotted against age to evaluate the influence of age on volume difference. RESULTS: Measurements derived from SyMRI and two SPM methods showed excellent agreements and strong correlations except for the CSF volume (CSFV) (intraclass correlation coefficients = 0.87-0.98; r = 0.78-0.96; relative volume difference other than CSFV = 6.8-18.5% [SyMRI vs. SPM T1] and 11.3-22.7% [SyMRI vs. SPM multi]). Dice coefficients of all brain tissues (except CSF) were in the range 0.78-0.91. The Bland-Altman plot and age-related volume difference change suggested that the volume differences between the two methods were influenced by the volume of each brain tissue and subject's age (p < 0.05). CONCLUSION: SyMRI and SPM segmentation results were consistent except for CSFV, which supports routine clinical use of SyMRI-based volumetry in pediatric neuroimaging. However, caution should be taken in the interpretation of the CSF segmentation results.

Improved white matter integrity after contralateral seventh cervical nerve transfer measured by tractographic representation.

Contralateral C7 (CC7) nerve transfer surgery was shown to significantly improve the spasticity condition and the motor function of paralyzed arms. However, the involvement of the white matter tract in the recovery process is not well established. We here investigated the possible biologic explanation for this phenomenon. A 62-year-old female patient, who suffered from spastic hemiparesis due to intracranial hemorrhage, underwent CC7 transfer surgery 13 years after the initial stroke event. Six months after the surgery, the patient's Modified Ashworth Scale and Fugl-Myere score improved, even though no specific rehabilitation programs were applied. Diffusion tensor imaging (DTI) was performed before and 6 months after the surgery. The pre-surgery DTI showed both ipsilesional and contralesional CST from the cerebral peduncles to the cortices. After surgery, however, only the contralesional CST was observed. In conclusion, functional alterations of the brain white matter tract after CC7 nerve transfer surgery possibly provided a neurophysiological substrate for ameliorating the spasticity and improving the motor function in a spastic hemiplegia patient.

Anomalous hyperplastic anterior choroidal artery and its mimicker: a case series.

The anomalous hyperplastic anterior choroidal artery (AchoA) is a rare anomaly due to incomplete distal annexation between the primitive AchoA and posterior cerebral artery (PCA). It is often misdiagnosed or misunderstood as a duplicated or fetal type PCA because of its supply distribution. In addition, its aneurysm incidence is much higher than the overall aneurysm incidence of AchoA. Thus, endovascular procedures or surgery without comprehensive understanding of this anomaly can cause critical complications. Herein, we present a case series of anomalous hyperplastic AchoA and its mimicker, along with schematic images for comprehensive understanding.

Transversus abdominis plane block for lumboperitoneal shunt surgery in idiopathic normal pressure hydrocephalus: a case report.

The transversus abdominis plane (TAP) block is an ideal pain control method used in surgeries that require abdominal wall incisions through the injection of an anesthetic solution into the plane between the internal oblique muscle and transversus abdominis muscle. Herein, we report an 83-year-old man who was diagnosed with idiopathic normal pressure hydrocephalus (iNPH) and underwent lumboperitoneal shunt surgery (LPS). The TAP block was performed before LPS, and the numerical rating scale for pain was 0 at day 1 after the surgery. The patient was discharged early at day 3 after surgery despite the patient being extremely old, as he reported quick relief from the postoperative abdominal pain. The TAP block can hence be considered for use before LPS in elderly patients with iNPH.

Clinical significance of vitamin D in idiopathic normal pressure hydrocephalus.

BACKGROUND: Although recent studies show vitamin D deficiency is associated with cognitive decline, urinary incontinence, and gait instability, there has been no study on the effect of vitamin D on idiopathic normal pressure hydrocephalus (iNPH) characterized by the classic symptom triad of cognitive decline, urinary incontinence, and gait instability. We investigated the clinical significance of vitamin D in patients with iNPH. METHODS: Between 2017 and 2020, 44 patients who underwent ventriculoperitoneal shunt surgery were divided into low (< 15 ng/mL) and high (≥ 15 ng/mL) vitamin D groups according to the concentration of 25(OH)D, an effective indicator of vitamin D status. They were respectively evaluated according to clinical and radiological findings. RESULTS: The low vitamin D group (n = 24) showed lower preoperative cognition compared to the high vitamin D group (n = 20) in terms of Korean-Mini Mental Status Examination (K-MMSE) and iNPH grading scale (iNPHGS) (K-MMSE: 20.5 ± 5.4 versus 24.0 ± 4.5, p = 0.041; iNPHGS cognitive score: 2 ± 0.9 versus 1 ± 0.6, p = 0.025). And the low vitamin D group showed pre- and postoperatively more severe urinary incontinence (preoperative iNPHGS urinary score: 1 ± 1.0 versus 0 ± 0.9, p = 0.012; postoperative iNPHGS urinary score:1 ± 1.0 versus 0 ± 0.9, p = 0.014). The score of narrow high-convexity sulci for the low vitamin D group was lower (low vitamin D group: 1 ± 0.7 versus high vitamin D group: 2 ± 0.4, p = 0.031). CONCLUSION: Lower concentration of vitamin D in iNPH may be related to lower preoperative cognition, pre- and postoperative urinary incontinence, and brain morphological change.

Spindle cell oncocytoma of the sella turcica with anaplastic features and rapid progression in short-term follow-up: a case report with proposal of distinctive radiologic features.

We present a rare case of spindle cell oncocytoma (SCO) of the sella turcica with malignant histologic features and rapid progression. A 42-year-old woman experienced bilateral blurred vision and was preoperatively misdiagnosed as having a pituitary macroadenoma on magnetic resonance imaging. After surgery, SCO was diagnosed by the histopathologic features of interlacing fascicles of spindle tumor cells with finely granular, eosinophilic cytoplasm. Focal anaplastic changes and necrosis were present. Immunohistochemically, the tumor cells were positive for vimentin, epithelial membrane antigen, S-100, galectin-3, and thyroid transcription factor 1. Four months later, the tumor had progressed, and second surgery with adjuvant radiotherapy was performed; the patients remains under observation. In this report, we proposed distinctive radiologic features for differential diagnosis between SCO and other pituitary tumors.

Clinical usefulness of deep learning-based automated segmentation in intracranial hemorrhage.

BACKGROUND: Doctors with various specializations and experience order brain computed tomography (CT) to rule out intracranial hemorrhage (ICH). Advanced artificial intelligence (AI) can discriminate subtypes of ICH with high accuracy. OBJECTIVE: The purpose of this study was to investigate the clinical usefulness of AI in ICH detection for doctors across a variety of specialties and backgrounds. METHODS: A total of 5702 patients' brain CTs were used to develop a cascaded deep-learning-based automated segmentation algorithm (CDLA). A total of 38 doctors were recruited for testing and categorized into nine groups. Diagnostic time and accuracy were evaluated for doctors with and without assistance from the CDLA. RESULTS: The CDLA in the validation set for differential diagnoses among a negative finding and five subtypes of ICH revealed an AUC of 0.966 (95% CI, 0.955-0.977). Specific doctor groups, such as interns, internal medicine, pediatrics, and emergency junior residents, showed significant improvement with assistance from the CDLA (p= 0.029). However, the CDLA did not show a reduction in the mean diagnostic time. CONCLUSIONS: Even though the CDLA may not reduce diagnostic time for ICH detection, unlike our expectation, it can play a role in improving diagnostic accuracy in specific doctor groups.

Robustness of magnetic resonance radiomic features to pixel size resampling and interpolation in patients with cervical cancer.

BACKGROUND: Radiomics is a promising field in oncology imaging. However, the implementation of radiomics clinically has been limited because its robustness remains unclear. Previous CT and PET studies suggested that radiomic features were sensitive to variations in pixel size and slice thickness of the images. The purpose of this study was to assess robustness of magnetic resonance (MR) radiomic features to pixel size resampling and interpolation in patients with cervical cancer. METHODS: This retrospective study included 254 patients with a pathological diagnosis of cervical cancer stages IB to IVA who received definitive chemoradiation at our institution between January 2006 and June 2020. Pretreatment MR scans were analyzed. Each region of cervical cancer was segmented on the axial gadolinium-enhanced T1- and T2-weighted images; 107 radiomic features were extracted. MR scans were interpolated and resampled using various slice thicknesses and pixel spaces. Intraclass correlation coefficients (ICCs) were calculated between the original images and images that underwent pixel size resampling (OP), interpolation (OI), or pixel size resampling and interpolation (OP+I) as well as among processed image sets with various pixel spaces (P), various slice thicknesses (I), and both (P + I). RESULTS: After feature standardization, ≥86.0% of features showed good robustness when compared between the original and processed images (OP, OI, and OP+I) and ≥ 88.8% of features showed good robustness when processed images were compared (P, I, and P + I). Although most first-order, shape, and texture features showed good robustness, GLSZM small-area emphasis-related features and NGTDM strength were sensitive to variations in pixel size and slice thickness. CONCLUSION: Most MR radiomic features in patients with cervical cancer were robust after pixel size resampling and interpolation following the feature standardization process. The understanding regarding the robustness of individual features after pixel size resampling and interpolation could help future radiomics research.

CT window trainable neural network for improving intracranial hemorrhage detection by combining multiple settings.

Window settings to rescale and contrast stretch raw data from radiographic images such as Computed Tomography (CT), X-ray and Magnetic Resonance images is a crucial step as data pre-processing to examine abnormalities and diagnose diseases. We propose a distant-supervised method for determining automatically the best window settings by attaching a window estimator module (WEM) to a deep convolutional neural network (DCNN)-based lesion classifier and training them in conjunction. Aside from predicting a flexible window setting for each raw image, we statistically identify the top four window settings by calculating the mean and standard deviations for the entire dataset. Images are scaled on each of the top settings estimated by WEM and following lesion classifiers are subsequently trained. We study the effects of only using the flexible window, the single fixed window as either a known default window used by radiologists or an estimated mean value, and two different approaches to combine results from the top window settings to improve the detection of intracranial hemorrhage (ICH) from brain CT images. Experimental results showed that using the top four window settings identified from the window estimator module and combining the results had the best performance.

Magnetic resonance imaging features of tumor and lymph node to predict clinical outcome in node-positive cervical cancer: a retrospective analysis.

BACKGROUND: Current chemoradiation regimens for locally advanced cervical cancer are fairly uniform despite a profound diversity of treatment response and recurrence patterns. The wide range of treatment responses and prognoses to standardized concurrent chemoradiation highlights the need for a reliable tool to predict treatment outcomes. We investigated pretreatment magnetic resonance (MR) imaging features of primary tumor and involved lymph node for predicting clinical outcome in cervical cancer patients. METHODS: We included 93 node-positive cervical cancer patients treated with definitive chemoradiotherapy at our institution between 2006 and 2017. The median follow-up period was 38 months (range, 5-128). Primary tumor and involved lymph node were manually segmented on axial gadolinium-enhanced T1-weighted images as well as T2-weighted images and saved as 3-dimensional regions of interest (ROI). After the segmentation, imaging features related to histogram, shape, and texture were extracted from each ROI. Using these features, random survival forest (RSF) models were built to predict local control (LC), regional control (RC), distant metastasis-free survival (DMFS), and overall survival (OS) in the training dataset (n = 62). The generated models were then tested in the validation dataset (n = 31). RESULTS: For predicting LC, models generated from primary tumor imaging features showed better predictive performance (C-index, 0.72) than those from lymph node features (C-index, 0.62). In contrast, models from lymph nodes showed superior performance for predicting RC, DMFS, and OS compared to models of the primary tumor. According to the 3-year time-dependent receiver operating characteristic analysis of LC, RC, DMFS, and OS prediction, the respective area under the curve values for the predicted risk of the models generated from the training dataset were 0.634, 0.796, 0.733, and 0.749 in the validation dataset. CONCLUSIONS: Our results suggest that tumor and lymph node imaging features may play complementary roles for predicting clinical outcomes in node-positive cervical cancer.

Can emphysema influence size discrepancy between radiologic and pathologic size measurement in subsolid lung adenocarcinomas?

BACKGROUND: To investigate the difference in the measured diameter of subsolid lung adenocarcinomas of thin-section computed tomography (TSCT) and pathology according to presence of emphysema. METHODS: A total of 268 surgically resected pathologic T1 or T2 adenocarcinomas visualized as subsolid nodules (SSNs) on TSCT were analyzed in 252 patients. Two observers measured the greatest diameters of the whole tumor (WTsize) and solid tumor (STsize) on TSCT in lung windows, classified nodules as part-solid or nonsolid, and recorded the presence of regional emphysema. Interobserver variability was determined with intraclass correlation coefficients (ICC). CT measurements were compared to pathologic size (Psize) and invasive size (PIsize) using the Wilcoxon signed-rank test. RESULTS: The interobserver agreement between the diameters measured by the two observers was strong for WTsize (ICC = 0.968 [95% confidence interval, 0.960-0.975]) and STsize (ICC = 0.966 [95% CI, 0.950-0.969]). Radiologic WTsize was significantly greater than Psize (P < 0.001), while STsize was less than PIsize. The WTsize of the emphysema group was better correlated with Psize than WTsize of the normal lung group (P = 0.001), while the STsize of the normal lung group was better correlated with PIsize than STsize of the emphysema group. The concordance rate in T staging between CT and pathologic analysis was better correlated in patients with normal lungs than in those with emphysema (P = 0.023). CONCLUSION: STsize on TSCT was underestimated in patients with emphysema, resulting in higher discordance in T staging between TSCT and pathologic analysis for subsolid lung adenocarcinomas.

Paradoxical Motor and Cognitive Function Recovery in Response to Zolpidem in a Patient with Hypoxic-ischemic Brain Injury: A Case Report.

We report an extremely rare case of a patient with hypoxic-ischemic brain injury who recovered consciousness and motor and cognitive functions due to paradoxical response after zolpidem administration. A 32-year-old woman who had attempted suicide by hanging was admitted. The patient had stabilized in a state of drowsy mentality, quadriparesis, dysphagia, and impaired cognition. Brain magnetic resonance imaging was suggestive of hypoxic ischemic brain injury and unilateral infarction in the right posterior cerebral artery territory. Due to sleep disturbance, zolpidem was administered, and paradoxically consciousness level and function returned to near-normal during the duration of the drug-effect. In addition to previous reports, our case characteristically showed remarkable motor and cognitive function recovery, not only consciousness level. The drug-effect time was gradually decreased after 18 months and absent after 3 years. We have reviewed related literature and discussed possible neuropharmacological and neurobiological mechanism.

Fracture of the Bare Spring of a Thoracic Endograft for Type A Aortic Dissection: A Case Report.

Retrograde type A aortic dissection (RTAD) following thoracic endovascular aortic repair is a devastating complication associated with high mortality rates. In particular, a deployed endograft in a bird-beak formation in an acute curve of the aortic arch can induce injury to the fragile aortic wall, with the subsequent development of RTAD. Here, we describe an extremely rare case of RTAD caused by fracture of the bare spring of the thoracic endograft for type A aortic dissection.