[Visualization of Cerebrospinal Fluid Dynamics by Respiratory Motion Using Phase Dispersion: Optimization of Spatial and Temporal Resolutions].

PURPOSE: The purpose of this study was to investigate the optimal spatial resolution and temporal resolution of dynamic improved motion-sensitized driven-equilibrium steady-state free precession for visualization of respiratory-driven cerebrospinal fluid (CSF) dynamics. METHODS: We investigated the differences in the visualization using the midsagittal cross-sections of nine healthy volunteers by three imaging conditions. (A: spatial resolution 0.49×0.49×5 mm, temporal resolution 1000 ms; B: 0.49×0.49×5 mm, 430 ms; and C: 0.78×0.78×5 mm, 200 ms). First, we calculated the CSF of the third and fourth ventricles and the signal-to-noise ratio (SNR) of the pons. Next, we calculated the signal intensity ratio (SIR) of the CSF flowing at 10 cm/s or more and the CSF flowing at 10 cm/s or less due to respiration. We also calculated the difference between the inspiration and expiration SIR. Furthermore, 1) the presence of flow in the third and fourth ventricles centered on the cerebral aqueduct and 2) the change in flow due to respiration was investigated by a three-point scale visual assessment by seven radiological technologists. RESULTS: The SNR was the highest in A, the next highest in B, and the lowest in C in all cases. There were significant differences between A and B, and A and C in CSF of the third and fourth ventricles. However, there was no significant difference between B and C. The CSF signal intensity changed with respiration. The SIR of the third ventricle was higher on inspiration and lower on expiration. Conversely, the SIR of the fourth ventricle was lower on inspiration and higher on expiration. There was a significant difference between A and C and B and C in each SIR (p<0.05). The difference between inspiration and expiration SIR was the highest in B, the next highest in A, and the lowest in C in both the third and fourth ventricles. Significant differences were found between A and C, and between B and C (p<0.05). There was no significant difference in the presence of flow in the third and fourth ventricles centered on the cerebral aqueduct (p=0.264). On the other hand, there was a significant difference between the imaging conditions in the change in flow due to respiration, with B having a higher value than the others (p<0.001). CONCLUSION: The optimal spatial and temporal resolutions were 0.49×0.49×5 mm and 430 ms, respectively. The results also suggest that it is important to carefully set the imaging conditions for the spatial and temporal resolutions because of the use of phase dispersion in this method.

Posterior Fossa Chronic Subdural Hematoma Associated with Supratentorial Chronic Subdural Hematoma.

OBJECTIVE: Chronic subdural hematoma (CSDH) in the posterior fossa has until now been reported in only 16 patients. This study clarified the frequency and characteristics of the posterior fossa CSDH through the use of magnetic resonance imaging (MRI) in patients with supratentorial CSDH. METHODS: We retrospectively examined presurgical MRI findings in patients with supratentorial CSDH who underwent surgery between 2006 and 2020. RESULTS: MRI revealed posterior fossa CSDH in 24 (7.3%) of 329 patients. Multivariable analyses demonstrated that anticoagulant treatment (P = 0.033, odds ratio [OR] 3.53), cerebrospinal fluid leak (P = 0.001, OR 18.5), and lack of previous trauma 3 weeks or more before admission (P = 0.027, OR 3.03) were risk factors of posterior fossa CSDH. Computed tomography could not show the hematomas in 20 patients (83.3%). All the posterior fossa CSDHs improved after supratentorial CSDH drainage. CONCLUSIONS: Posterior fossa CSDH was observed on MRI in a minority of patients with supratentorial CSDH. Although most patients with posterior fossa CSDH had good outcomes, large posterior fossa CSDH sometimes must be treated surgically, according to previous reports.

Evaluation of Cardiac- and Respiratory-driven Cerebrospinal Fluid Motions by Applying the S-transform to Steady-state Free Precession Phase Contrast Imaging.

PURPOSE: To extract the status of hydrocephalus and other cerebrospinal fluid (CSF)-related diseases, a technique to characterize the cardiac- and respiratory-driven CSF motions separately under free breathing was developed. This technique is based on steady-state free precession phase contrast (SSFP-PC) imaging in combination with a Stockwell transform (S-transform). METHODS: 2D SSFP-PC at 3 T was applied to measure the CSF velocity in the caudal-cranial direction within a sagittal slice at the midline (N = 3) under 6-, 10-, and 16-s respiratory cycles and free breathing. The frequency-dependent window width of the S-transform was controlled by a particular scaling factor, which then converted the CSF velocity waveform into a spectrogram. Based on the frequency bands of the cardiac pulsation and respiration, as determined by the electrocardiogram (ECG) and respirator pressure sensors, Gaussian bandpass filters were applied to the CSF spectrogram to extract the time-domain cardiac- and respiratory-driven waveforms. RESULTS: The cardiac-driven CSF velocity component appeared in the spectrogram clearly under all respiratory conditions. The respiratory-driven velocity under the controlled respiratory cycles was observed as constant frequency signals, compared to a time-varying frequency signal under free breathing. When the widow width was optimized using the scale factor, the temporal change in the respiratory-driven CSF component was even more apparent under free breathing. CONCLUSION: Velocity amplitude variations and transient frequency changes of both cardiac- and respiratory-driven components were successfully characterized. These findings indicated that the proposed technique is useful for evaluating CSF motions driven by different cyclic forces.

Fusing of Preoperative Magnetic Resonance and Intraoperative O-arm Images in Deep Brain Stimulation Enhance Intuitive Surgical Planning and Increase Accuracy of Lead Placement.

Intraoperative fluoroscopy and microelectrode recording (MER) are useful techniques for guiding lead placement in deep brain stimulation (DBS). Recent advances in magnetic resonance imaging (MRI) have enabled information on the location of the basal ganglia, as the target of DBS, to be obtained preoperatively. However, intraoperative images with few artifacts are required to enable accurate fusion of preoperative imaging data with intraoperative lead position data. With our method, we first fuse preoperative MRI and pre-frame fixed computed tomography (CT) images, then fuse the CT images exactly after mounting the frame, using this fusion image as a platform image. Compared with before and after frame fixation, the pre-frame fixed CT has less artifacts, facilitating the identification of soft tissues such as the ventricles and cortical surface on pre-frame fixed CT images. By fusing the structural information for these soft tissues between pre-frame fixed CT and MR images, this fusion process can provide improved accuracy that is intuitively understood by the surgeon. Using platform images, surgical planning and intraoperative lead positioning can then be evaluated on the same coordinate axis. Positional data on the lead acquired as three-dimensional (3D) data are then added to the platform image. The proposed surgical steps permit the acquisition of accurate lead position data.

Characterization of Cardiac- and Respiratory-driven Cerebrospinal Fluid Motions Using a Correlation Mapping Technique Based on Asynchronous Two-dimensional Phase Contrast MR Imaging.

PURPOSE: The cardiac- and respiratory-driven components of cerebrospinal fluid (CSF) motion characteristics and bulk flow are not yet completely understood. Therefore, the present study aimed to characterize cardiac- and respiratory-driven CSF motions in the intracranial space using delay time, CSF velocity waveform correlation, and displacement. METHODS: Asynchronous two-dimensional phase-contrast at 3T was applied to measure the CSF velocity in the inferior-superior direction in a sagittal slice at the midline (N = 12) and an axial slice at the foramen magnum (N = 8). Volunteers were instructed to engage in six-second respiratory cycles. The calculated delay time and correlation coefficients of the cardiac- and respiratory-driven velocity waveforms, separated in the frequency domain, were applied to evaluate the propagation of the CSF motion. The cardiac- and respiratory-driven components of the CSF displacement and motion volume were calculated during diastole and systole, and during inhalation and exhalation, respectively. The cardiac- and respiratory-driven components of the velocity, correlation, displacement, and motion volume were compared using an independent two-sample t-test. RESULTS: The ratio of the cardiac-driven CSF velocity to the sum of the cardiac- and respiratory-driven CSF velocities was higher than the equivalent respiratory-driven ratio for all cases (P < 0.01). Delay time and correlation maps demonstrated that the cardiac-driven CSF motion propagated more extensively than the respiratory-driven CSF motion. The correlation coefficient of the cardiac-driven motion was significantly higher in the prepontine (P < 0.01), the aqueduct, and the fourth ventricle (P < 0.05). The respiratory-driven displacement and motion volume were significantly greater than the cardiac-driven equivalents for all observations (P < 0.01). CONCLUSION: The correlation mapping technique characterized the cardiac- and respiratory-driven CSF velocities and their propagation properties in the intracranial space. Based on these findings, cardiac-driven CSF velocity is greater than respiratory-induced velocity, but the respiratory-driven velocity might displace farther.

Simple Identification of Cerebrospinal Fluid Turbulent Motion Using a Dynamic Improved Motion-sensitized Driven-equilibrium Steady-state Free Precession Method Applied to Various Types of Cerebrospinal Fluid Motion Disturbance.

The motion of cerebrospinal fluid (CSF) within the subarachnoid space and ventricles is greatly modulated when propagating synchronously with the cardiac pulse and respiratory cycle and path through the nerves, blood vessels, and arachnoid trabeculae. Water molecule movement that propagates between two spaces via a stoma, foramen, or duct presents increased acceleration when passing through a narrow area and can exhibit "turbulence." Recently, neurosurgeons have started to perform fenestration procedures using neuroendoscopy to treat hydrocephalus and cystic lesions. As part of the postoperative evaluation, a noninvasive diagnostic technique to visualize the water molecules at the fenestrated site is necessary. Because turbulence is observed at this fenestrated site, an imaging technique appropriate for observing this turbulence is essential. We therefore investigated the usefulness of a dynamic improved motion-sensitized driven-equilibrium steady-state free precession (Dynamic iMSDE SSFP) sequence of magnetic resonance imaging that is superior for ascertaining turbulent motions in healthy volunteers and patients. Images of Dynamic iMSDE SSFP from volunteers revealed that CSF motion at the ventral surface of the brainstem and the third ventricle is augmented and turbulent. Moreover, our findings confirmed that this technique is useful for evaluating treatments that utilize neuroendoscopy. As a result, Dynamic iMSDE SSFP, a simple sequence for visualizing CSF motion, entails a short imaging time, can extensively visualize CSF motion, does not require additional processes such as labeling or trigger setting, and is anticipated to have wide-ranging clinical applications in the future.

Benefits and Risks of CT Angiography Immediately after Emergency Arrival for Patients with Intracerebral Hematoma.

Computed tomography angiography (CTA) immediately after diagnosis of intracerebral hematoma (ICH) on noncontrast CT in the emergency room has benefits, which consist of early diagnosis of secondary ICH and prediction of hematoma growth using the spot sign in primary ICH, but CTA also involves possible risks of acute kidney injury (AKI) and adverse reactions. The purpose of this study was to evaluate the benefits and risks of CTA. A total of 1423 consecutive adult patients diagnosed with ICH who were admitted within 3 days of onset between 2010 and 2017 were retrospectively analyzed. Of 1082 patients undergoing CTA, 162 patients (15.0%) showed secondary ICH, and the sensitivity of CTA for secondary ICH was 95.7%. Of 920 patients with primary ICH, a logistic regression model using the spot sign and four other previously reported risk factors (antiplatelet agents, anticoagulants, interval from onset to arrival, hematoma volume) with an area under the curve (AUC) of 0.787 significantly improved model performance to predict hematoma growth compared with a model using the same four factors without the spot sign (AUC: 0.697) (DeLong's test: P = 0.0002). Rates of AKI occurrence were 9.0% and 9.8% in patients with and without CTA, respectively. The odds ratio of AKI in patients with CTA adjusted by reported risk factors was 1.16 (95% confidence interval: 0.72-1.95, P = 0.5548). Emergency CTA following noncontrast CT in patients with ICH could be useful for early diagnosis of secondary ICH and prediction of hematoma growth using the spot sign in primary ICH with little risk.

Neuroendoscopic Evacuation for Spontaneous Cerebellar Hemorrhage Is a Safe and Secure Approach and May Become a Mainstream Technique.

Patients with spontaneous cerebellar hemorrhage present with rapidly deteriorating neurological symptoms due to a hematoma-induced mass effect in the brainstem. We compared the standard surgical approach of a suboccipital craniectomy with neuroendoscopic surgery for treating spontaneous cerebellar hemorrhage. We performed a retrospective analysis of 41 patients indicated for surgery to treat spontaneous cerebellar hemorrhage. At our hospital, craniectomy was performed until 2010, and neuroendoscopic surgery was performed thereafter when a qualified surgeon was available. Duration of surgery and intraoperative blood loss were lower in the neuroendoscopic surgery group. The extent of hematoma removal and the percentage of patients requiring shunting were similar between groups. The mass effect was resolved in all patients in both groups, and no substantial re-bleeding was observed in either group. The outcomes at discharge were comparable between the two groups. Our surgeons used the supine lateral position, which involves fewer burdens to the patient than the prone position. Selection of the site of the burr hole is important to avoid the midline and to avoid the area exactly above the transverse and sigmoid sinus. Our results suggest that minimally invasive neuroendoscopic surgery is safe and superior to craniectomy due to shortened duration of surgery and decreased intraoperative bleeding.

Basal Cistern Effacement and Pseudo-Subarachnoid Hemorrhage on Computed Tomography Images of Chronic Subdural Hematoma.

OBJECTIVE: Computed tomography images of patients with chronic subdural hematoma (CSDH) sometimes show obliteration of the basal cistern with high density in an obliterated Sylvian cistern, termed pseudo-subarachnoid hemorrhage (SAH). The present study aimed to clarify the characteristics and outcomes of these conditions. METHODS: We retrospectively investigated 669 consecutive patients who were surgically treated for CSDH between January 2006 and May 2019. RESULTS: Basal cistern effacement and pseudo-SAH were found in 24 (3.6%) and 11 (1.6%) patients, respectively. Predictors of basal cistern effacement in patients with CSDH were younger age, cerebrospinal fluid leak, and bilateral CSDH (P < 0.05). In patients with basal and Sylvian cistern effacement, the significantly different main features to differentiate patients with and without pseudo-SAH were younger age, cerebrospinal fluid leak, and thick small hematomas on computed tomography slices of the Sylvian cistern (P < 0.05). Magnetic resonance imaging showed that high-density areas in the Sylvian cistern of pseudo-SAH on precontrast computed tomography images corresponded to the M1 segment of the middle cerebral artery. The outcomes of patients with basal cistern effacement and of patients with pseudo-SAH did not differ from other patients with CSDH, although rates of surgical complications were significantly higher among patients with basal cistern effacement. CONCLUSIONS: Although the outcomes of patients with basal cistern effacement and pseudo-SAH were similar to outcomes of other patients with CSDH, problematic postsurgical complications and cerebrospinal fluid leaks were more likely to arise in such patients.

Recurrent Trigeminal Neuralgia Caused by a Subsequently Developed Offending Artery Within a Short Period.

BACKGROUND: Recurrent trigeminal neuralgia after successful microvascular decompression is not rare. CASE DESCRIPTION: A 72-year-old woman who presented with typical right trigeminal neuralgia had been successfully treated by microvascular decompression with transposition of the superior cerebellar artery. However, she complained of trigeminal neuralgia on the ipsilateral side 14 months after the microvascular decompression. Redo microvascular decompression showed that the anterior inferior cerebellar artery, which had not been detected at the initial surgery, compressed the right trigeminal nerve. CONCLUSIONS: This case is an unusual type of recurrent trigeminal neuralgia because of a subsequently developed offending vessel within a short period.

Prehospital information and spot sign are complementary predictors of post-admission outcomes of intracerebral hematoma.

Prehospital information of patients with intracerebral hematomas (ICHs), including systolic blood pressure (SBP), Glasgow Coma Scale (GCS), and neurological deterioration (ND), defined as GCS score worsening ≥2 points, has been reported, though relationships among the prehospital information and clinical factors, including the spot sign, which was a reported predictor of outcomes, were not clarified. The purpose of this study was to elucidate relationships among prehospital information, the spot sign, and clinical outcomes after admission using multivariate analysis. Consecutive patients with ICHs admitted within 6 h of onset from 2009 to 2017 were investigated. Among 645 eligible patients, prehospital ND was found in 107 (16.6%). Multiple regression analysis showed that predictors of hematoma volume were prehospital GCS (p < 0.0001), prehospital ND (p < 0.0001), anticoagulant use (p = 0.0254), and cortical hematoma (p < 0.0001). Predictors of emergency surgery or death within 24 h were prehospital SBP (p = 0.0005, unit OR: 1.01), prehospital GCS (p < 0.0001, unit OR: 0.82), prehospital ND (p = 0.0002, OR: 3.26), and hematoma volume (p < 0.0001, unit OR: 1.04). Predictors of death at discharge were prehospital GCS (p < 0.0001, unit OR: 0.75), prehospital ND (p = 0.0001, OR: 3.49), and age (p = 0.0008, unit OR: 1.036). On the other hand, none of the 3 items of prehospital information were predictors of the spot sign or hematoma enlargement. The prehospital information and the spot sign could predict post-admission outcomes in a complementary fashion. Prehospital information might be used as a reference for preparing emergency treatment, as well as possible future blood pressure-lowering treatment, before emergency department arrival.

Changing the Currently Held Concept of Cerebrospinal Fluid Dynamics Based on Shared Findings of Cerebrospinal Fluid Motion in the Cranial Cavity Using Various Types of Magnetic Resonance Imaging Techniques.

The "cerebrospinal fluid (CSF) circulation theory" of CSF flowing unidirectionally and circulating through the ventricles and subarachnoid space in a downward or upward fashion has been widely recognized. In this review, observations of CSF motion using different magnetic resonance imaging (MRI) techniques are described, findings that are shared among these techniques are extracted, and CSF motion, as we currently understand it based on the results from the quantitative analysis of CSF motion, is discussed, along with a discussion of slower water molecule motion in the perivascular, paravascular, and brain parenchyma. Today, a shared consensus regarding CSF motion is being formed, as follows: CSF motion is not a circulatory flow, but a combination of various directions of flow in the ventricles and subarachnoid space, and the acceleration of CSF motion differs depending on the CSF space. It is now necessary to revise the currently held concept that CSF flows unidirectionally. Currently, water molecule motion in the order of centimeters per second can be detected with various MRI techniques. Thus, we need new MRI techniques with high-velocity sensitivity, such as in the order of 10 µm/s, to determine water molecule movement in the vessel wall, paravascular space, and brain parenchyma. In this paper, the authors review the previous and current concepts of CSF motion in the central nervous system using various MRI techniques.

The combination of warfarin use and the spot sign leads to detrimental outcomes in patients with intracerebral hematomas.

OBJECTIVES: While warfarin use and the presence of the spot sign on computed tomography angiography are associated with a high frequency of hematoma enlargement and high mortality among patients with intracerebral hematomas (ICHs), the effects of various combinations of warfarin use and/or the spot sign have never been clarified. The combinations of both or either of warfarin use and/or the spot sign were used to investigate their relationships with hematoma enlargement and mortality before the introduction of prothrombin complex concentrate (PCC) treatment. PATIENTS AND METHODS: Consecutive patients with ICHs admitted within 6 h of onset from 2009 to 2017 were investigated. RESULTS: Of 703 eligible patients, the combinations of warfarin use and spot sign-present and of warfarin use and spot sign-absent were seen in 23 (3.3%) and 35 patients (5.0%), respectively. The combination of warfarin use and spot sign-present was a predictor of hematoma enlargement (p < 0.05). In regard to mortality (13.5% for all patients), mortality with the combination of warfarin use and spot sign-present was 52.2%, which was significantly higher than in the 3 other groups. Multivariate analysis showed that the combination of warfarin use and spot sign-present was a significant predictor of mortality (p < 0.05). CONCLUSION: Warfarin users with ICHs showing spot signs, who accounted for approximately 40% of ICH patients with warfarin use, showed a high frequency of hematoma enlargement and high mortality. This group was regarded as high-risk patients and should be considered candidates for prompt administration of PCC.

Effects of Pre-Existing Comorbidities on Outcomes in Patients with Chronic Subdural Hematoma.

OBJECTIVE: The number of patients with chronic subdural hematoma (CSDH) showing comorbidities and/or impaired activities of daily living (ADL) before the onset of CSDH has increased with the recent aging of society. The purposes of this study were to evaluate ADL worsening by comparing premorbid ADL and ADL at discharge and to investigate the effects of pre-existing comorbidity-related clinical factors on the outcomes. METHODS: A total of 570 patients with CSDH admitted from 2006 to 2016 were studied retrospectively. Clinical factors, including pre-existing comorbidities, related to outcomes were identified by multivariate analysis. A variation of the modified Rankin Scale (mRS) using 5 united categories of mRS scores 0/1, 2, 3/4, 5, and dead was used for evaluation of ADL. RESULTS: Of 570 patients, 390 (68.4%) had pre-existing comorbidities and 120 (21.1%) showed premorbid impaired ADL (mRS scores 2 and worse). Considering pre-existing impaired ADL, ADL deteriorated after CSDH in 92 patients (16.1%), whereas ADL impairment at discharge was found in 173 patients (30.4%). Comorbidities related to ADL deterioration on multivariate analysis were hemodialysis and chronic heart failure. Antithrombotic use for cardiovascular diseases was a predictor of acute-on-chronic subdural hematoma, which was the sole common predictor for ADL deterioration and the occurrence of surgical complications. CONCLUSIONS: In patients with CSDH, pre-existing comorbidity-linked factors related to outcomes were hemodialysis, chronic heart failure, and antithrombotic use. Patients with acute-on-chronic subdural hematoma with these factors should be regarded as a high-risk group.

Cardiac-driven Pulsatile Motion of Intracranial Cerebrospinal Fluid Visualized Based on a Correlation Mapping Technique.

PURPOSE: A correlation mapping technique delineating delay time and maximum correlation for characterizing pulsatile cerebrospinal fluid (CSF) propagation was proposed. After proofing its technical concept, this technique was applied to healthy volunteers and idiopathic normal pressure hydrocephalus (iNPH) patients. METHODS: A time-resolved three dimensional-phase contrast (3D-PC) sampled the cardiac-driven CSF velocity at 32 temporal points per cardiac period at each spatial location using retrospective cardiac gating. The proposed technique visualized distributions of propagation delay and correlation coefficient of the PC-based CSF velocity waveform with reference to a waveform at a particular point in the CSF space. The delay time was obtained as the amount of time-shift, giving the maximum correlation for the velocity waveform at an arbitrary location with that at the reference location. The validity and accuracy of the technique were confirmed in a flow phantom equipped with a cardiovascular pump. The technique was then applied to evaluate the intracranial CSF motions in young, healthy (N = 13), and elderly, healthy (N = 13) volunteers and iNPH patients (N = 13). RESULTS: The phantom study demonstrated that root mean square error of the delay time was 2.27%, which was less than the temporal resolution of PC measurement used in this study (3.13% of a cardiac cycle). The human studies showed a significant difference (P < 0.01) in the mean correlation coefficient between the young, healthy group and the other two groups. A significant difference (P < 0.05) was also recognized in standard deviation of the correlation coefficients in intracranial CSF space among all groups. The result suggests that the CSF space compliance of iNPH patients was lower than that of healthy volunteers. CONCLUSION: The correlation mapping technique allowed us to visualize pulsatile CSF velocity wave propagations as still images. The technique may help to classify diseases related to CSF dynamics, such as iNPH.

A Case of Occipital Malignant Peripheral Nerve Sheath Tumor with Neurofibromatosis Type 1.

INTRODUCTION: The prognosis of malignant peripheral nerve sheath tumor (MPNST) with neurofibromatosis type 1 (NF-1) is worse than that of a solitary MPNST, because of the tumor size and location difficult to resect completely. We experienced a case of MPNST in the occipital region with NF-1. CASE REPORT: A 59-year-old woman presented with NF-1 and an MPNST of the occipital region. We performed wide excision involving the occipital bone, and reconstructed with a titanium plate and a free latissimus dorsi muscle flap. Despite three operations and postoperative radiotherapy, the tumor locally recurred after each surgery; further complicated by lung and mediastinal metastasis. Adjuvant therapy was insufficient to control local recurrence, which was observed intracranially, resulting in sagittal sinus invasion. Thirty months after the initial surgery, the patient died of respiratory failure due to lung metastasis. CONCLUSION: MPNST with NF-1 has poorer prognosis than that of a solitary lesion. Recently, it is reported in several literature that combination therapy with surgery and radiotherapy improve survival rates. But as we presented, when the complete local resection with free margin could not achieved due to the size and anatomical location of the tumor, the effectiveness of radiotherapy is not sufficient to control local recurrence.

Research into the Physiology of Cerebrospinal Fluid Reaches a New Horizon: Intimate Exchange between Cerebrospinal Fluid and Interstitial Fluid May Contribute to Maintenance of Homeostasis in the Central Nervous System.

Cerebrospinal fluid (CSF) plays an essential role in maintaining the homeostasis of the central nervous system. The functions of CSF include: (1) buoyancy of the brain, spinal cord, and nerves; (2) volume adjustment in the cranial cavity; (3) nutrient transport; (4) protein or peptide transport; (5) brain volume regulation through osmoregulation; (6) buffering effect against external forces; (7) signal transduction; (8) drug transport; (9) immune system control; (10) elimination of metabolites and unnecessary substances; and finally (11) cooling of heat generated by neural activity. For CSF to fully mediate these functions, fluid-like movement in the ventricles and subarachnoid space is necessary. Furthermore, the relationship between the behaviors of CSF and interstitial fluid in the brain and spinal cord is important. In this review, we will present classical studies on CSF circulation from its discovery over 2,000 years ago, and will subsequently introduce functions that were recently discovered such as CSF production and absorption, water molecule movement in the interstitial space, exchange between interstitial fluid and CSF, and drainage of CSF and interstitial fluid into both the venous and the lymphatic systems. Finally, we will summarize future challenges in research. This review includes articles published up to February 2016.

A Case of a TSH-secreting Pituitary Adenoma Associated with Evans' Syndrome.

We present a case of a TSH-secreting pituitary adenoma (TSHoma) associated with Evans' syndrome. A 30-year-old woman was referred to our hospital due to purpura and ecchymoses on her limb and body and epistaxis. Evans' syndrome was diagnosed based on idiopathic thrombocytopenic purpura and autoimmune hemolytic anemia. She had a history of malocclusion and thyroid gland enlargement 4 years prior to admission. Endocrinological tests and magnetic resonance imaging also revealed that this patient had hyperthyroidism due to the TSHoma and that this adenoma concomitantly secreted GH. Recently, several cases of Evans' syndrome were associated with hyperthyroidism caused by autoimmune thyroid disease, such as Graves' disease, suggesting that these 2 conditions may have a common immunological basis. To the best of our knowledge, there is no case report of Evans' syndrome associated with hyperthyroidism due to TSHoma. Our report suggests that the excess of thyroid hormone itself promotes autoimmunity in Evans' syndrome. Thus, early treatment for hyperthyroidism is necessary in TSHomas because of the possibility that thyroid hormone normalization may prevent the development of Evans' syndrome.

Cerebral Infarction following Acute Subdural Hematoma in Infants and Young Children: Predictors and Significance of FLAIR Vessel Hyperintensity.

A phenomenon of cerebral infarction following acute subdural hematoma (ASDH) in infants and young children, termed cerebral infarction following ASDH (CIASDH), has been well recognized, though both its mechanisms and risk factors have been poorly understood. The purpose of the present study was to investigate the predictors for CIASDH in a population of ASDH, and to evaluate the imaging studies to presume the mechanisms of CIASDH. We retrospectively examined consecutive children 6 years of age or younger, who were diagnosed with ASDH and were admitted to our hospital between 2000 and 2014. In 57 consecutive children with ASDH, 12 (21.1%) developed CIASDH. The multivariate analysis revealed five predictors for CIASDH: presence of seizure, consciousness disturbance at admission, absence of skull fracture, hematoma thickness ≥ 5 mm on computed tomography (CT), and midline shift ≥ 3 mm on CT (p < 0.05). In three of six patients (50%) undergoing magnetic resonance (MR) imaging/fluid-attenuated inversion recovery (FLAIR) within 5 days of admission, serpentine hyperintensities in the subarachnoid space (FLAIR vessel hyperintensities) were demonstrated. MR angiography showed neither occlusion nor stenosis of the cerebral arteries. Single photon emission CT performed at admission in one patient showed a cerebral blood flow reduction in the ASDH side. All the children with CIASDH showed unfavorable outcomes at discharge. Children showing multiple predictors at admission should be carefully observed for development of CIASDH. Evaluation of the imaging studies suggested that a blood flow disturbance in the level of peripheral arteries to microcirculation was one candidate for possible mechanisms to induce the CIASDH.