Predictors of cerebrospinal fluid GeneXpert MTB/RIF positivity in patients with tuberculous meningitis:A prospective cohort study

Objective:To identify the clinical,laboratory,and radiological markers that could predict a positive GeneXpert result in patients suspected of tuberculous meningitis.Methods:In this prospective,observational study,patients with tuberculous meningitis were systematically evaluated.Various clinical,laboratory[including cerebrospinal fluid(CSF)microscopy,culture,and GeneXpert],and neuroimaging factors were examined.All participants were administered anti-tuberculous treatment and corticosteroids.A six-month follow-up was done to evaluate the outcome.Results:Of the 116 patients studied,54(46.6%)tested positive for GeneXpert,while 62(53.4%)were negative.Third cranial nerve involvement(OR 3.71,95%CI 1.052-13.09,P=0.04)and the presence of basal exudates on neuroimaging(OR 5.22,95%CI 2.03-13.42,P=0.001)emerged as independent predictive factors for a positive GeneXpert result.A positive CSF GeneXpert result(P=0.002)and drug resistance(P=0.004)were significantly linked to adverse outcomes.Additionally,a high score on the Medical Research Council stageⅢ(OR 5.64,95%CI 1.18-26.87,P=0.03)and elevated CSF cell counts(OR 1.002,95%CI 1.00-1.001,P=0.03)were identified as independent predictors of poor prognosis.Conclusions:Third cranial nerve involvement and the presence of basal exudates were significant indicators of a positive GeneXpert result.MRC stageⅢdisability and elevated CSF cell counts predicted poor outcomes.

Surgical treatment of mixed cervical spondylosis with spontaneous cerebrospinal fluid leakage: A case report

BACKGROUND Spontaneous cerebrospinal fluid(CSF)leaks associated with cervical spondylosis are rare.To our knowledge,only a few cases have been reported in which treatment is challenging and varies from case to case.Here,we review the literature and describe the surgical treatment of a 70-year-old woman who presented with a CSF leak due to a cervical spine spur.CASE SUMMARY A 70-year-old female patient who was treated for a cerebral infarction,presented with complains of weakness in the right lower extremity and a feeling of stepping on cotton.The patient underwent regular neck massage and presented with neck and right shoulder pain radiating to the right upper extremity one-month ago.Magnetic resonance imaging showed a strip of leaking cerebrospinal fluid posterior to the C1-4 vertebrae,and computed tomography showed a“sickleshaped”disc prolapse with calcification in C4/5.We chose to perform an anterior cervical discectomy.When the prolapsed C4/5 disc was scraped,clear fluid leakage was observed,and exploration revealed a 1 mm diameter rupture in the anterior aspect of the dura mater,which was compressed continuously with cotton patties,with no significant cerebrospinal fluid leakage after 1 h.CONCLUSION Three months after surgery,the patient was asymptomatic and follow-up imaging demonstrated complete resolution.

Hydrocephalic cerebrospinal fluid flowing rotationally with pulsatile boundaries:A mathematical simulation of the thermodynamical approach

To study the kinematics of flow rate and ventricular dilatation,an analytical perturbation approach of hydrocephalus has been devised.This research provides a comprehensive investigation of the characteristics of cerebrospinal fluid(CSF)flow and pressure in a hydrocephalic patient.The influence of hydrocephalic CSF,flowing rotationally with realistic dynamical characteristics on pulsatile boundaries of subarachnoid space,was demonstrated using a nonlinear controlling system of CSF.An analytical perturbation method of hydrocephalus has been developed to investigate the biomechanics of fluid flow rate and the ventricular enlargement.In this paper presents a detailed analysis of CSF flow and pressure dynamics in a hydrocephalic patient.It was elaborated with a nonlinear governing model of CSF to show the influence of hydrocephalic CSF,flowing rotationally with realistic dynamical behaviors on pulsatile boundaries of subarachnoid space.In accordance with the suggested model,the elasticity factor changes depending on how much a porous layer,in this case the brain parenchyma,is stretched.It was improved to include the relaxation of internal mechanical stresses for various perturbation orders,modelling the potential plasticity of brain tissue.The initial geometry that was utilised to create the framework of CSF with pathological disease hydrocephalus and indeed the output of simulations using this model were compared to the actual progression of ventricular dimensions and shapes in patients.According to this observation,the non-linear and elastic mechanical phenomena incorporated into the current model are probably true.Further modelling of ventricular dilation at a normal pressure may benefit from the existence of a valid model whose parameters approximate genuine mechanical characteristics of the cerebral cortex.

CfDNA-based liquid biopsy of cerebrospinal fluid in medulloblastoma

Medulloblastoma(MB)is the most common childhood embryonal malignant tumour in the central nervous system.The diagnosis,prognosis and therapeutic targets of MB depend on the molecular characteristics of the tumor,and it is a great challenge to obtain the tissue samples from the patients with brain tumor.Genomic changes found in cell-free DNA(cfDNA)of cerebrospinal fluid(CSF)can predict genomic changes present in tumor tissue,fluid biopsy of CSF can detect the genomic profile of tumor-associated cfDNA and evaluate cfDNA as a marker of measurable residual disease(MRD)in a relatively noninvasive manner,which provides the evidence of"individualized precision therapy"for MB patients.In this paper,we reviewed the recent studies in medulloblastoma based on cfDNA Liquid Biopsy of CSF.

Role of cerebrospinal fluid lactate in diagnosing meningitis in critically ill patients

BACKGROUND Meningitis is a life-threatening clinical condition associated with high mortality and morbidity.Early diagnosis and specific treatment may improve outcomes.Lack of specific clinical signs or tests make the diagnosis challenging.AIM To assess the efficacy of cerebrospinal fluid(CSF)lactate in diagnosing meningitis in critically ill patients.METHODS A prospective,observational cohort study was carried out in a neuro-medical intensive care unit(ICU)over a 22 mo period.Adult patients,with suspected meningitis admitted in ICU,were serially recruited.Patients who refused consent,those with peripheral sensorineural deficit,or with any contraindication to lumber puncture were excluded.CSF cytology,bio-chemistry,lactates,culture and polymerase chain reaction based meningo-encephalitis panel were evaluated.Patients were divided in two groups based on clinical diagnosis of meningitis.The efficacy of CSF lactate in diagnosing meningitis was evaluated and compared with other tests.RESULTS Seventy-one patients were included and 23 were diagnosed with meningitis.The mean values of CSF total leucocyte count(TLC),proteins and lactates were significantly higher in meningitis group.There was a significant correlation of CSF lactate levels with CSF cultures and meningo-encephalitis panel.CSF lactate(>2.72 mmol/L)showed good accuracy in diagnosing meningitis with an area under the curve of 0.81(95% confidence interval:0.69-0.93),sensitivity of 82.6%,and specificity 72.9%.These values were comparable to those of CSF TLC and protein.Twelve patients with bacterial meningitis had significantly higher CSF lactate(8.9±4.7 mmol/L)than those with non-bacterial meningitis(4.2±3.8 mmol/L),P=0.006.CONCLUSION CSF lactate may be used to aid in our diagnosis of meningitis in ICU patients.CSF lactate(>2.72 mmol/L)showed good accuracy,sensitivity,and specificity in diagnosing meningitis and may also help to differentiate between bacterial and non-bacterial meningitis.

Abdominal Cerebrospinal Fluid Pseudocyst—A Rare Complication of Ventriculoperitoneal Shunt

An abdominal cerebrospinal fluid pseudocyst is a rare complication of ventriculoperitoneal shunt. Several theories have been suggested to explain its occurrence. The main symptoms are painful abdominal distension and vomiting, abdominal distension on examination, as abdominal ultrasound and computed tomography confirm its diagnosis. The treatment involves drainage associated with drain relocation and resection of the pseudocyst’s wall. We report two patients diagnosed with this condition who underwent surgical treatment. The first patient had an unremarkable 12-month follow-up, while the second died on the seventh postoperative day due to intravascular disseminated coagulation. In these patients, the cause has not been identified;however, an infection cannot be ruled out.

Serial lumbar puncture reduces cerebrospinal fluid (CSF) infection during removal of hemorrhagic CSF in aneurysmal subarachnoid hemorrhage after endovascular coiling

The present study aimed to compare the complications and clinical outcomes of serial lumbar puncture（LP） and lumbar cerebrospinal fluid（CSF） drainage（LD） of patients with aneurysmal subarachnoid hemorrhage and provide more evidence to guide clinical management.In this retrospective study,41 and 39 aneurysmal subarachnoid hemorrhage patients were enrolled in the LP and LD group,respectively.Clinical outcomes,including CSF infection,intracerebral hemorrhage,vasospasm,hydrocephalus,death,length of stay,duration of drainage and the Glasgow Outcome Scale score were compared between the two groups.By comparing with the LP group,the LD group showed a significantly higher rate of CSF infection（P= 0.029） and shorter duration of drainage（P〈 0.001）.Both groups displayed similar rates of vasospasm,hydrocephalus,intracerebral hemorrhage,the Glasgow Outcome Scale score one month after endovascular coiling and length of stay（P〉 0.05,respectively）.In conclusion,both LD and serial LP are effective methods in the treatment of aneurysmal subarachnoid hemorrhage; besides,serial LP can reduce the incidence of CSF infection in draining hemorrhagic CSF in aneurysmal subarachnoid hemorrhage after endovascular coiling.

Review of Thoracic Endovascular Aneurysm Repair (TEVAR), Spinal Cord Ischemia (SCI), Cerebrospinal Fluid (CSF) Drainage and Blood Pressure (BP) Augmentation

The object of this review is to examine the role of TEVAR in causing SCI. The anatomy and physiology of blood flow to the spinal cord is examined. The role of auto regulation of blood flow within the spinal cord is also examined. This review examines the reported results from the scientific literature of the effect of thoracic aortic aneurysm repair on spinal cord blood flow. In the light of the-se findings several conclusions can reasonably be reached. These conclusions are that the development of SCI can reasonably be predicted based on complexity and extent of the TEVAR procedure performed and BP augmentation and CSF drainage can significantly reduce the impact of SCI.

Frequency of Bacterial Organisms Isolated from Cerebrospinal Fluid (CSF) of Children under Five Years in Windhoek from 2010 to 2014

Bacterial meningitis (BM) is a life-threatening condition which affects the central nervous system (CNS). Its incidence rate is estimated between 0.22 - 2.66 and 0.81 - 6.1 cases/1000 lives worldwide and in Africa respectively. The objective of this study was to determine the frequency of bacterial organisms isolated from CSF of children less than five years old in Windhoek. A retrospective analysis was performed on 784 results of CSF submitted to the Namibia Institute of Pathology (NIP) from January 2010 to August 2014. The results showed that out of the suspected meningitis cases, 18 (28.6%) were due to Streptococcus pneumoniae, making it the frequently isolated organism, followed by Staphylococcus aureus 7 (11.1%), Escherichia coli 5 (7.9%) and Haemophilus influenzae 4 (6.3%). Streptococcus pneumoniae showed high resistance to penicillin 17 (70.5%) & cotrimoxazole 16 (93.7%) and 100% susceptibility to ciprofloxacin (5), vancomycin (13) & ceftri-axone (8). Haemophilus influenzae showed moderate resistance to cotrimoxazole 3 (66%) & tet-racycline 2 (50%). It showed 100% sensitivity to chloramphenicol (4), cefuroxime (2) & ceftriaxone (3). Neisseria meningitidis showed high resistance to cotrimoxazole by 100% (n = 2) and high sensitivity to chloramphenicol (n = 2), ceftriaxone & penicillin by 100% (n = 2). Streptococcus agalactiae was resistant to tetracycline and sensitive to penicillin & erythromycin by 100% (n = 1). Streptococcus pneumoniae was isolated the most in this current study and it had high resistance to penicillin & cotrimoxazole. There was a significant difference between results CSF culture and PCR, Gram stain, CSF cell count, protein & glucose, as all comparisons yielded in P values less than 0.05, indicating a significant statistical association.

Treatment of spinal cord injury by transplantation of cells via cerebrospinal fluid

It is very important to probe into the axonal regeneration and functional recovery of central nervous system （CNS） after implantation of cells into cerebrospinal fluid （CSF） for spinal cord injury （SCI）. Transplantation of cells via CSF poses great potentials for SCI in clinic. Studies on administration of cells via CSF indicate that the method is safe and convenient. The method is more suitable to treating multiple lesions of the CNS since it does not produce open lesions. However, there are disputes over its promotion effects on axonal regeneration and functional recovery of spinal cord after injury; and some questions, such as the mechanisms of functional recovery of spinal cord, the proper time window of cell transplantation, and cell types of transplantation, still need to be handled. This review summarized the method of cell transplantation via CSF for treatment of SCI.

Changes in HIF-1α, VEGF, NGF and BDNF Levels in Cerebrospinal Fluid and TheirRelationship with Cognitive Impairment in Patients with Cerebral Infarction

Summary： This study was carried out to investigate the role of intrinsic neuroprotective mechanisms in the occurrence and development of vascular cognitive impairment （VCI） with the goal of providing a target for the treatment and prevention of VCI. Inpatients with proven cerebral infarction on cranial computed tomography （CT） were recruited as the ischemic cerebrovascular diseases （ICVD） group, and the patients with mixed stroke were excluded. In ICVD group, 12 patients were diagnosed as having VCI and served as VCI group. Inpatients undergoing surgical operation in our hospital were enrolled as control group. Double-antibody sandwich enzyme-linked immunosorbent assay （ELISA） was employed to detect the levels of hypoxia-inducible factor 1-alpha （HIF-1α）, vascular endothelial growth factor （VEGF）, nerve growth factor （NGF） and brain-derived neurotrophic factor （BDNF） in the cerebrospinal fluid of patients with ICVD. Associations between the levels of these factors and the Mini-Mental State Examination （MMSE） score were evaluated. In ICVD and VCI groups, the levels of HIF-1α and NGF in the cerebrospinal fluid were markedly lower than those in control group （P=-0.037 and P=0.000; P=0.023 and P=-0.005）. In ICVD and VCI groups, the MMSE score was negatively related to VEGF level in the cerebrospinal fluid （r=-0.327, P=0.021; r=-0.585, P=0.046）. In VCI group, HIF-1α level was correlated with NGF level （r=0.589, P=0.044）. HIF-1α and NGF are involved in ischemic and hy- poxic cerebral injury. The HIF signaling pathway plays an important role in intrinsic neuroprotection. Upregulation and maintenance of HIF-1α and NGF expression may attenuate VCI. Changes in VEGF levels are related to the occurrence and development of cognitive impairment.

Serum and cerebrospinal fluid tau protein level as biomarkers for evaluating acute spinal cord injury severity and motor function outcome

Tau protein, a microtubule-associated protein, has a high specific expression in neurons and axons. Because traumatic spinal cord injury mainly affects neurons and axons, we speculated that tau protein may be a promising biomarker to reflect the degree of spinal cord injury and prognosis of motor function. In this study, 160 female Sprague-Dawley rats were randomly divided into a sham group, and mild, moderate, and severe spinal cord injury groups. A laminectomy was performed at the T8 level to expose the spinal cord in all groups. A contusion lesion was made with the NYU-MASCIS impactor by dropping a 10 g rod from heights of 12.5 mm(mild), 25 mm(moderate) and 50 mm(severe) upon the exposed dorsal surface of the spinal cord. Tau protein levels were measured in serum and cerebrospinal fluid samples at 1, 6, 12, 24 hours, 3, 7, 14 and 28 days after operation. Locomotor function of all rats was assessed using the Basso, Beattie and Bresnahan locomotor rating scale. Tau protein concentration in the three spinal cord injury groups(both in serum and cerebrospinal fluid) rapidly increased and peaked at 12 hours after spinal cord injury. Statistically significant positive linear correlations were found between tau protein level and spinal cord injury severity in the three spinal cord injury groups, and between the tau protein level and Basso, Beattie, and Bresnahan locomotor rating scale scores. The tau protein level at 12 hours in the three spinal cord injury groups was negatively correlated with Basso, Beattie, and Bresnahan locomotor rating scale scores at 28 days(serum: r =-0.94; cerebrospinal fluid: r =-0.95). Our data suggest that tau protein levels in serum and cerebrospinal fluid might be a promising biomarker for predicting the severity and functional outcome of traumatic spinal cord injury.

Diagnostic Value of Cerebrospinal Fluid T-SPOT.TB for Tuberculousis Meningitis in China

The aim of this study was to evaluate the diagnostic value of the cerebrospinal fluid（CSF） T‐SPOT.TB test for the diagnosis of TB meningitis（TBM）. A retrospective analysis of 96 patients with manifested meningitis was conducted; T‐SPOT.TB test was performed for diagnosing TBM to determine the diagnostic sensitivity, specificity, positive predictive value（PPV）, and negative predictive value（NPV）. A receiver operating characteristic（ROC） curve was also drawn to assess the diagnostic accuracy. The sensitivity, specificity, PPV, and NPV of CSF T‐SPOT.TB test were 97.8%, 78.0%, 80.3%, and 97.5%, respectively, for 52 patients（54.2%） of the 96 enrolled patients. The area under the curve（AUC） was 0.910, and the sensitivities of CSF T‐SPOT.TB for patients with stages I, II, and III of TBM were 96.7%, 97.2%, and 98.9%, respectively. CSF T‐SPOT.TB test is a rapid and accurate diagnostic method with higher sensitivity and specificity for diagnosing TBM.

Acrylamide exposure impairs blood-cerebrospinal fluid barrier function

Previous studies show that chronic acrylamide exposure leads to central and peripheral neu- ropathy. However, the underlying mechanisms remained unclear. In this study, we examined the permeability of the blood-cerebrospinal fluid barrier, and its ability to secrete transthyretin and transport leptin of rats exposed to acrylamide for 7, 14, 21 or 28 days. Transthyretin levels in cerebrospinal fluid began to decline on day 7 after acrylamide exposure. The sodium fluorescein level in cerebrospinal fluid was increased on day 14 after exposure. Evans blue concentration in cerebrospinal fluid was increased and the cerebrospinal fluid/serum leptin ratio was decreased on days 21 and 28 after exposure. In comparison, the cerebrospinal fluid/serum albumin ratio was increased on day 28 after exposure. Our findings show that acrylamide exposure damages the blood-cerebrospinal fluid barrier and impairs secretory and transport functions. These changes may underlie acrylamide-induced neurotoxicity.

Cerebrospinal Fluid Biomarkers in Dementia Patients with Cerebral Amyloid Angiopathy

Objective To study the changes of biomarkers in cerebrospinal fluid(CSF) in cerebral amyloid angiopathy(CAA) dementia and Alzheimer's disease.Methods Levels of amyloid protein β(Aβ42,Aβ40) and phosphorylated Tau-protein(P-tau) in CSF and ratio of Aβ42/Aβ40 were tested in 5 cases with CAA dementia and 20 cases with Alzheimer's disease collected at Peking Union Medical College Hospital from December 2001 to March 2011.Results The levels of Aβ42,Aβ40,and P-tau in CSF and ratio of Aβ42/Aβ40 were(660.4±265.2) ng/L,(7111.0±1033.4) ng/L,(71.8±51.5) ng/L,and 0.077±0.033,respectively in CAA dementia and(663.6±365.6) ng/L,(5115.0±2931.1) ng/L,(47.7±38.8) ng/L,and 0.192±0.140,respectively in Alzheimer's disease patients.There were no statistically significant differences between CAA dementia and Alzheimer's disease in terms of these CSF biomarkers(all P>0.05).Conclusion Measurements of CSF biomarkers may not be helpful in differential diagnosis of CAA and Alzheimer's disease.

MANAGEMENT OF CEREBROSPINAL FLUID LEAKAGE FOLLOWING CERVICAL SPINE SURGERY

Objective To investigate the management and outcome of cerebrospinal fluid leakage(CSFL)after cervical surgery.Methods Medical records of 642 patients who underwent cervical surgery between December 1999 and December 2005 at our hospital were retrospectively reviewed.Five patients complicated by CSFL after surgery were enrolled,of which 4 cases were complicated after ossified posterior longitudinal ligament or posterior vertebral osteophyte resection directly injuring the dura,and 1 case after posterior cervical double-door laminoplasty without observed dural injury during surgery.Of the 5 CSFL cases,4 cases occurred at 1-3 days after operation and 1 case at 9 days after operation.All 5 postoperative CSFL cases were treated through wound drainage removal,wound sutures,prophylactic antibiotics,and continuous subarachnoid drainage in the elevated head position.Results All 5 CSFL cases experienced leakage cessation within 1-3 days and wound healing within 4-8 days,and subarachnoid drainage lasted 11-16 days with an average volume of 320 mL(range,150-410 mL).Four cases experienced headache,nausea and vomiting,1 case suffered from somnolence and hyponatremia,and symptoms subsided after symptomatic treatment and intravenous fluid administration.All patients were followed up for an average of 32 months(range,22-50 months).No occurrence of cerebrospinal fluid cyst or wound infection was observed.CSFL produced no significant negative effects upon neuromuscular function recovery.Conclusion Continuous subarachnoid cavity drainage in combination with elevated head position is a simple and safe non-surgical method in treatment of CSFL following cervical surgery.

Cognitive impairment in multiple sclerosis: lessons from cerebrospinal fluid biomarkers

Cognitive impairment is a common clinical manifestation of multiple sclerosis,but its pathophysiology is not completely understood.White and grey matter injury together with synaptic dysfunction do play a role.The measurement of biomarkers in the cerebrospinal fluid and the study of their association with cognitive impairment may provide interesting in vivo evidence of the biological mechanisms underlying multiple sclerosis-related cognitive impairment.So far,only a few studies on this topic have been published,giving interesting results that deserve further investigation.Cerebrospinal fluid biomarkers of different pathophysiological mechanisms seem to reflect different neuropsychological patterns of cognitive deficits in multiple sclerosis.The aim of this review is to discuss the studies that have correlated cerebrospinal fluid markers of immune,glial and neuronal pathology with cognitive impairment in multiple sclerosis.Although preliminary,these findings suggest that cerebrospinal fluid biomarkers show some correlation with cognitive performance in multiple sclerosis,thus providing interesting insights into the mechanisms underlying the involvement of specific cognitive domains.

Cerebrospinal fluid and neural stem cell niche control

Neurogenesis from inner brain neural stem cells （NSCs） is a process which takes place continuously in mammals through- out their life. However, the main ontogenic difference is the intensity of neurogenesis, which commences as a very intensive and global activity in the early embryonic brain （neural tube）, persists in fetal and newborn stages, and declines significantly in adulthood, becoming restricted to specific places with low neurogenic activity such as the subventricular zone （SVZ） and the subgranular zone （SGZ） in the dentate gyrus （DG） of the hippocampus.

Cerebrospinal fluid and blood biomarkers in Alzheimer’s disease

Due to an ever aging society and growing prevalence of Alzheimer’s disease(AD),the challenge to meet social and health care system needs will become increasingly difficult.Unfortunately,a definite ante mortem diagnosis is not possible.Thus,an early diagnosis and identification of AD patients is critical for promising,early pharmacological interventions as well as addressing health care needs.The most advanced and most reliable markers areβ-amyloid,total tau and phosphorylated tau in cerebrospinal fluid(CSF).In blood,no single biomarker has been identified despite an intense search over the last decade.The most promising approaches consist of a combination of several bloodbased markers increasing the reliability,sensitivity and specificity of the AD diagnosis.However,contradictory data make standardized testing methods in longitudinal and multi-center studies extremely difficult.In this review,we summarize a range of the most promising CSF and blood biomarkers for diagnosing AD.

Osmotic pressure of serum and cerebrospinal fluid in patients with suspected neurological conditions

Interstitial fluid movement in the brain parenchyma has been suggested to contribute to sustaining the metabolism in brain parenchyma and maintaining the function of neurons and glial cells.The pulsatile hydrostatic pressure gradient may be one of the driving forces of this bulk flow.However,osmotic pressure- related factors have not been studied until now.In this prospective observational study,to elucidate the relationship between osmolality (mOsm/kg) in the serum and that in the cerebrospinal fluid (CSF),we simultaneously measured the serum and CSF osmolality of 179 subjects with suspected neurological conditions.Serum osmolality was 283.6 ± 6.5 mOsm/kg and CSF osmolality was 289.5 ± 6.6 mOsm/kg.Because the specific gravity of serum and CSF is known to be 1.024–1.028 and 1.004–1.007,respectively,the estimated average of osmolarity (mOsm/L) in the serum and CSF covered exactly the same range (i.e.,290.5–291.5 mOsm/L).There was strong correlation between CSF osmolality and serum osmolality,but the difference in osmolality between serum and CSF was not correlated with serum osmolality,serum electrolyte levels,protein levels,or quotient of albumin.In conclusion,CSF osmolarity was suggested to be equal to serum osmolarity.Osmolarity is not one of the driving forces of this bulk flow.Other factors such as hydrostatic pressure gradient should be used to explain the mechanism of bulk flow in the brain parenchyma.This study was approved by the Institutional Review Board of the Tohoku University Hospital (approval No.IRB No.2015-1-257) on July 29,2015.