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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.We retrospectively examined presurgical MRI findings in patients with supratentorial CSDH who underwent surgery between 2006 and 2020.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.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.

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).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.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.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.

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.

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.

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.

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.

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.

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.

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.We retrospectively investigated 669 consecutive patients who were surgically treated for CSDH between January 2006 and May 2019.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 (P0.05). 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 (P0.05). 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.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.

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.

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.Consecutive patients with ICHs admitted within 6 h of onset from 2009 to 2017 were investigated.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).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.

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.

INTRODUCTION Magnetic resonance perfusion imaging is considered to be available as grading of brain tumor and follow-up of brain treatment. One of the methods, arterial spin labeling (ASL), is a test that is useful for patients with renal impairment and contrast agent allergy and has low invasiveness because it does not use a contrast agent. However, there have been no reports of ASL in intraoperative MRI (iMRI). PURPOSE In this hospital iMRI (1.5T), it was examined whether ASL could be used to evaluate residual tumor in patients under general anesthesia. CASE STUDY A 75-year-old woman with right temporal lobe Glioblastoma. 43-year-old man, left temporal lobe Diffuse astrocytoma. All performed ASL at the time of MRI imaging for navigation before induction of anesthesia just before surgery and iMRI. In all cases, the blood pressure at iMRI was maintained, and Post Label Delay (PLD) calculated the optimal PLD from the carotid artery velocity measured by iMRI, and defined it as 1800–2200 ms, and performed ASL. RESULTS Actually, imaging by iMRI was almost difficult to visualize, and reflux was not recognized not only in the tumor but also in the gray matter. DISCUSSION The blood flow velocity measurement in the internal carotid artery is performed by the phase contrast method by intraoperative MRI, and the CBF decreases because propofol used during the operation decreases the CBF and also the brain metabolism. However, it has been suggested that it is one of the factors that make evaluation with ASL difficult. Although the iMRI of our hospital is 1.5 T, which is also a subject of investigation, it is thought that there is a limit to ASL imaging in the case of general anesthesia with propofol even from the calculated PLD. CONCLUSION ASL in iMRI at our hospital was not useful.

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.

Cerebrospinal fluid (CSF) in the intracranial space has a microscopic circulation called “bulk flow”. Since bulk flow is relating to clearance of wastes from neurons via glymphatic system, visualization of its flow velocity is necessary. In this work, we examined a quantitative visualization technique based on q-space imaging (QSI) obtained with proton MRI. A phantom with microscopic circulation of physiological saline through a silicon tube of 6 mm in inner diameter was placed in a vertical 9.4-T MRI. Flow rate of the pump was set at 0.1 ∼ 0.5 mL/min with 0.1 mL/min steps after calibrating at 0.5 or 1.0 mL/min. Strength of motion probing gradient (MPG) was changed from −43.4 to +43.4 mT/m with 6.2 mT/m steps. The direction of MPG was foot-head (FH) direction. This resulted in a q-space of 32 points at each voxel in an axial section. The q-space data was then Fourier-transformed into a probability density function (PDF) of proton displacement. The peak position of PDF indicated the water proton flow, while the width indicated diffusion. The spatial distribution of the flow velocity was then obtained by dividing the displacement by the MPG interval at all the voxels. The velocity distributions appeared to be laminar at all the flow rate settings. The resultant flow velocities were from 57.80 to $300.72\ \mu\mathrm{m}/\mathrm{s}$ , and were highly correlated ( $r=0.99,\ p ) with the velocities created by the pump. In conclusion, observation of microscopic flow of the order of several $10\ \mu \mathrm{m}/\mathrm{s}$ was sufficiently performed by the QSI technique, even when the self-diffusion exists.

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 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.

Background Few studies have examined the risk of computed tomography angiography (CTA) during the acute phase of spontaneous intracerebral hemorrhage (ICH), while the benefits of CTA in ICH have been well-documented. The present study investigated both the benefits of identifying spot signs, which are supposed to indicate hematoma enlargement after admission, and risks of CTA performed during the acute phase of ICH. Methods We retrospectively assessed 323 consecutive patients with spontaneous ICHs admitted to our hospital between April 2009 and March 2012 and who underwent CTA on admission. Results In 80 patients (24.7 %), spot signs were demonstrated on CTA source images. Multivariate analysis revealed two independent factors correlated with presence of the spot sign: age and hematoma volume (p

ObjectNew approaches for understanding CSF motion in healthy individuals and patients with hydrocephalus and Chiari malformation are presented. The velocity and the pressure gradient of CSF motion were determined using phase contrast (PC) MRI.MethodsThe authors examined 11 healthy control subjects and 2 patients (1 with hydrocephalus and 1 with Chiari malformation), using 4-dimensional PC (4D-PC) MRI and a newly developed computer analysis method that includes calculation of the pressure gradient from the velocity field. Sagittal slices including the center of the skull and coronal slices of the foramen of Monro and the third ventricle were used.ResultsIn the ventricular system, mixing and swirling of the CSF was observed in the third ventricle. The velocity images showed that the CSF was pushed up and back down to the adjacent ventricle and then returned again to the third ventricle. The CSF traveled bidirectionally in the foramen of Monro and sylvian aqueduct. Around the choroid plexus in the lateral ventricle, the CSF motion was stagnant and the CSF pressure gradient was lower than at the other locations. An elevated pressure gradient was observed in the basal cistern of the subarachnoid space. Sagittal imaging showed that the more prominent pressure gradients originated around the cisterna magna and were transmitted in an upward direction. The coronal image showed a pressure gradient traveling from the central to the peripheral subarachnoid spaces that diminished markedly in the convexity of the cerebrum. The 2 patients, 1 with secondary hydrocephalus and 1 with Chiari malformation, were also examined.ConclusionsThe observed velocity and pressure gradient fields delineated the characteristics of the CSF motion and its similarities and differences among the healthy individuals and between them and the 2 patients. Although the present results did not provide general knowledge of CSF motion, the authors' method more comprehensively described the physiological properties of the CSF in the skull than conventional approaches that do not include measurements of pressure gradient fields.

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.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.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.

Flexible endoscopes can be used in areas that are difficult to approach using rigid endoscopes. No current real-time navigation systems identify the tip of the flexible neuroendoscope. We have developed a flexible neuroendoscope mounted with a magnetic field sensor tip position-tracking system and evaluated the accuracy of this magnetic field neuronavigation system. Based on an existing flexible neuroendoscope, we created a prototype with a built-in magnetic field sensor in the tip. A magnetic field measurement device provides a magnetic field with a working volume of 500 × 500 × 500 mm in front of the device. The device consists of a flat field generator that creates a pulsed magnetic field, connected to a system control unit that interfaces with a computer. The magnetic field sensor (1.8 × 9 mm) was sealed in a site 0.9 mm from the endoscope tip. Accuracy of neuroendoscope tracking was measured using a three-dimensional coordinate-measuring machine that measures the position of objects along 3 axes, with an error of about 3 µm. The accuracy for this neuroendoscope with built-in magnetic field sensor was root mean square error of 1.2 mm and standard deviation of 0.5 mm. This magnetic field neuronavigation system enables real-time tracking of the tip of the flexible neuroendoscope. Application of this flexible neuroendoscope to intraoperative navigation appears promising, and may provide new advantages for minimally invasive endoscopic surgery.

Introduction. Chronic thalamic stimulation has been confirmed as an effective treatment for tremor. The optimal target has been commonly accepted to be situated within the ventral thalamus, but a standard trajectory of the deep brain stimulation (DBS) electrode has not yet been established. Materials and Methods. A 53-year-old man with an 11-year history of essential tremor was treated by DBS of the thalamus. In this patient, we had a chance to compare the effects of different trajectory angles of the DBS electrode on tremor. Results. Intraoperative stimulation with the DBS electrode temporarily inserted at a high angle to the horizontal plane of the anterior commissure-posterior commissure (AC-PC) line to cover only the nucleus ventralis intermedius (Vim) was not effective. In contrast, stimulation with the DBS electrode permanently implanted at a low angle, covering a wide area extending from the nucleus ventralis oralis (Vo) to the Vim, reduced the tremor. Conclusion. We report on the case of a patient who showed different effects on tremor depending on the trajectory angle of the DBS electrode to the AC-PC line. The insertion trajectory of the DBS electrode may be an important factor for the treatment of tremor.

Object In February 2006, the magnetic resonance/x-ray/operating room (MRXO) suite opened at the authors' institution. This is the first hybrid neurosurgical procedure suite to combine magnetic resonance (MR) imaging, computed tomography (CT), and angiography within a neurosurgical operating room (OR). In the present paper the authors describe the concept of the MRXO as well as their first 10 months of experience using this suite, and discuss its advantages and limitations. Methods In the MRXO suite, the combined OR and angiography (OR–angiography) station is located in the middle of the suite, and the MR imaging and CT scanning stations are each installed in an adjoining bay connected to the OR–angiography station by shielded sliding doors. The surgical, MR imaging, angiography, and CT tables are positioned in order of use. The patient lies on a fully MR imaging– and radiography-compatible mobile patient tabletop that is used to move the patient quickly and safely among the tables in the imaging and operating components of the MRXO suite. Results The authors performed all interventional procedures safely. The specially designed operating tabletop of the MRXO suite reduced the limitations on neurosurgeons during standard neurosurgical procedures. This hybrid suite helps to provide high-quality intraoperative imaging, greatly reducing the risk of unexpected events during the procedure. Conclusions The MRXO suite, which combines OR and imaging equipment, represents a significant milestone in the improvement of neurosurgical diagnosis and treatment and other interventional procedures. Another advantage of the MRXO suite is its cost-effectiveness, which is partly due to its streamlined imaging procedure.

Purpose: We compared the depiction of pulsatile CSF motion obtained by 4-dimensional phase-contrast velocity mapping (4D-VM) with that by time-spatial labeling inversion pulse (time-SLIP) technique in the presence of membrane structures. Materials and Methods: We compared the 2 techniques using a flow phantom comprising tubes with and without a thin rubber membrane and applied the techniques to 6 healthy volunteers and 2 patients to analyze CSF dynamics surrounding thin membrane structures, such as the Liliequist membrane (LM), or the wall of an arachnoid cyst. Results: Phantom images exhibited propagation of the flow and pressure gradient beyond the membrane in the tube. In contrast, fluid labeled by the time-SLIP technique showed little displacement from the blockage of spin travelling by the membrane. A similar phenomenon was observed around the LM in healthy volunteers and the arachnoid cyst wall in a patient. Conclusion: Four-dimensional phase-contrast velocity mapping permitted visualization of the propagation of CSF pulsation through the intracranial membranous structures. This suggests that 4D-VM and the time-SLIP technique provide different information on flow and that both techniques are useful for classifying the pathophysiological status of CSF and elucidating the propagation pathway of CSF pulsation in the cranium.

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.

Background and Purpose— A spot sign is a bright spot on computed tomography angiography source images, which is predictive of hematoma growth in spontaneous intracerebral hemorrhage, although the cause of the spot sign is unclear. Our aim was to investigate the spot sign seen on computed tomography angiography and a striate artery, which is a presumed site of intracerebral hemorrhage bleeding origin in the putamen. Methods— In consecutive cases of spontaneous intracerebral hemorrhage in the putamen, spot signs and striate arteries were evaluated. Coronal reformat images of computed tomography angiography were created to visualize the striate arteries. Acute deterioration, defined as hematoma enlargement, emergency hematoma removal, or death within the day of admission, was reviewed. Results— Of the 141 patients undergoing computed tomography angiography, 15 of the 30 patients (50%) who had spot signs showed an intrahematoma striate artery (termed spot and tail sign), which was a linear density extending from the middle cerebral artery toward the spot sign. Acute deterioration occurred more frequently in patients who had a spot and tail sign compared with patients who had spot signs without intrahematoma striate arteries ( P P Conclusions— The presence of a spot and tail sign, assumed to indicate active bleeding from the striate artery, could be a more sensitive predictor of acute deterioration than the presence of a simple spot sign.

In the present study, we examined the behavior and state of water molecules in immature and mature rat brains by measuring the components of magnetic resonance (MR) water proton transverse relaxation time (T 2). We also performed morphological examination of immature and mature rat brains using electron microscopy (EM). We then compared the fraction of T 2 component and the EM findings. Midbrains of male Wistar rats were examined at various time points ranging from 4 h to 12 weeks after birth. T 2 was measured by MR, and the ratios of intra- to extracellular spaces were determined by EM in each stage. T 2 consisted of two components: fast T 2 (100 ms). During maturation, values of fast T 2 decreased dramatically, but slow T 2 remained constant. However, the fraction accounted for by slow T 2 decreased from 59% to 9% during maturation. Morphological examination showed that the extracellular space fraction of the midbrain decreased from 49% to 5% during maturation. Thus, morphological change correlated well with changes in slow T 2; in other words, multicomponent T 2 results showed a close correlation with tissue compartmentalization. MR relaxation times obtained by means of multicomponent analysis can thus be used to measure intra- and extracellular space fractions.

This article describes the use of 3D reconstruction for preoperative surgical planning and intraoperative navigation for cortical surgery. Before each surgical procedure, a detailed structural and functional model is reconstructed from magnetic resonance imaging scans and functional mapping modalities. These models, when integrated with direct intraoperative cortical mapping, create an integral 3D map of the cortical surface surrounding the lesion and its relation to the whole brain anatomy. A navigation system is coupled to the surgical field using skin-to-skin registration involving infrared light-emitting diode instrument tracking. This allows accurate guidance in the mapped 3D space. These detailed, patient-specific 3D maps of the brain are used as a method of accurately assessing the surgical approach, determining the potential neurologic risks, and navigating within the brain. One hundred fifty-five patients have been treated with this system for either preoperative planning or surgical navigation.

To assess a newly proposed noninvasive technique for evaluating intracranial pressure (ICP) index and brain compliance (BC) index based on an inverse analysis of a brain-circulation-equivalent electrical circuit (EC) model, in which cerebrospinal fluid (CSF) flow and arterial flow rates measured by using the phase contrast method are used as currents.Quantitative phase contrast flow measurements were performed by using a 1.5-T scanner for 25 volunteers and 23 patients with chronic increased ICP state. Bilateral carotid and verrtebral arteries and CSF flows were modeled by a pair of electrical circuits inductively coupled by a transformer. The ICP index was defined as the voltage of the second order circuit, while the BC index was calculated as the ratio between the mutual indeuctance of the transformer and the reactance in the second order circuit.The ICP index obtained by the EC correlated well with the pressure gradient obtained by the Navier-Stokes Technique (NS-PG). The combination of NS-PG and BC index by the EC appeared to be appropriate for characterizing the brain circulation status of the volunteers.This noninvasive ICP and BC index measurement technique is more useful for asessment of intracranial condition.

A novel technique to analyze propagation of fluid flow pattern based on magnetic resonance (MR) velocimetry has been developed and applied to cerebrospinal fluid (CSF) dynamics in intracranial space. This technique evaluates spatial distribution of the correlation time as well as correlation coefficient of velocity waveform with respect to an arbitrary reference waveform using quantitative velocity imaging with phase contrast (PC) method. Phantom experiments demonstrated that the propagation of the flow had no delay time because saline was incompressible and the pipes used for the phantom was rigid. In contrast, the propagation of CSF flow in a healthy volunteer appeared to have particular distribution of correlation time indicating that there was delay in the flow. These preliminary results suggest that the technique may yield abundant information concerning on CSF dynamics and thus useful to analyze driving force as well as abnormality in CSF dynamics.

Objective We used three-dimensional reconstructed magnetic resonance images for planning the operations of 16 patients with various cerebrovascular diseases. We studied the cases of these patients to determine the advantages and current limitations of our computer-assisted surgical planning system as it applies to the treatment of vascular lesions. Methods Magnetic resonance angiograms or thin slice gradient echo magnetic resonance images were processed for three-dimensional reconstruction. The segmentation, based on the signal intensities and voxel connectivity, separated each anatomic structure of interest, such as the brain, vessels, and skin. A three-dimensional model was then reconstructed by surface rendering. This three-dimensional model could be colored, made translucent, and interactively rotated by a mouse-controlled cursor on a workstation display. In addition, a three-dimensional blood flow analysis was performed, if necessary. The three-dimensional model was used to assist in three stages of surgical planning, as follows: 1) to choose the best method of intervention, 2) to evaluate surgical risk, 3) to select a surgical approach, and 4) to localize lesions. Results The generation of three-dimensional models allows visualization of pathological anatomy and its relationship to adjacent normal structures, accurate lesion volume determination, and preoperative computer-assisted visualization of alternative surgical approaches. Conclusion Computer-assisted surgical planning is useful for patients with cerebrovascular disease at various stages of treatment. Lesion identification, therapeutic and surgical option planning, and intraoperative localization are all enhanced with these techniques.

We have used MRI-based three-dimensional (3D) reconstruction and a real-time, frameless, stereotactic navigation device to facilitate the removal of seizure foci in children suffering from intractable epilepsy. Using this system, the location of subdural grid and strip electrodes is recorded on the 3D model to facilitate focus localization and resection. Ten operations were performed, including 2 girls and 8 boys ranging in age from 3 to 17, during which 3D reconstruction and surgical instrument tracking navigation was used. In all the cases, the patients tolerated the procedure well and showed no postoperative neurological deficits. We believe this to be a valuable tool for a complete and safe resection of seizure foci, thereby reducing the incidence of postoperative neurological deficits and significantly improving the overall quality of life of the patients.

Lymphocytic hypophysitis (LYH) is a chronic inflammation that primarily affects the pituitary gland. This disorder has recently been classified into lymphocytic adenohypophysitis (LAH), lymphocytic infundibulo-neurohypophysitis (LINH), and lymphocytic infundibulo-panhypophysitis (LIPH) according to the affected area. We report a case of LINH in a 68-year-old woman who presented with diabetes insipidus (DI). In this case, the posterior lobe was affected in both endocrinological assessment and magnetic resonance imaging (MRI) findings. In contrast, the anterior pituitary was not affected in endocrinological assessment but was affected in MRI findings. Indeed, the patient did not develop hypopituitarism. We believed that these clinical and radiological features were unique in regard to the classification of LYH. To confirm the classification of LYH and the distinction from pituitary adenoma, a pituitary biopsy was performed. Based on the pathological and endocrinological assessment, the patient's disorder was finally diagnosed as a variant of LINH. Current evidence recommends that surgical intervention for LYH should be avoided because the natural course of LYH is essentially self-limiting. Therefore, the accumulation of the knowledge of many variants of LYH is important for the preoperative differential diagnosis of pituitary masses. Our clinical observation could be useful for avoiding unnecessary surgical intervention.

Flexible endoscopes can be used in areas that are difficult to approach using rigid endoscopes. No current real-time navigation systems identify the tip of the flexible neuroendoscope. We have developed a flexible neuroendoscope mounted with a magnetic field sensor tip position-tracking system and evaluated the accuracy of this magnetic field neuronavigation system. Based on an existing flexible neuroendoscope, we created a prototype with a built-in magnetic field sensor in the tip. A magnetic field measurement device provides a magnetic field with a working volume of 500 × 500 × 500 mm in front of the device. The device consists of a flat field generator that creates a pulsed magnetic field, connected to a system control unit that interfaces with a computer. The magnetic field sensor (1.8 × 9 mm) was sealed in a site 0.9 mm from the endoscope tip. Accuracy of neuroendoscope tracking was measured using a three-dimensional coordinate-measuring machine that measures the position of objects along 3 axes, with an error of about 3 µm. The accuracy for this neuroendoscope with built-in magnetic field sensor was root mean square error of 1.2 mm and standard deviation of 0.5 mm. This magnetic field neuronavigation system enables real-time tracking of the tip of the flexible neuroendoscope. Application of this flexible neuroendoscope to intraoperative navigation appears promising, and may provide new advantages for minimally invasive endoscopic surgery.

In February 2006, Tokai University Hospital officially opened the imaging operation suite, which is the first hybrid neurosurgical procedure suite to combine magnetic resonance imaging, computed tomography and angiography with a neurosurgical operating room. Here, we describe the concept of the imaging operation suite and the first 4 years' experience using this suite.

This paper describes the use of an on-duty safety nurse, a surgical safety manual and a checklist as an essential precursor to evaluating how these approaches affect surgical quality, communication in surgery crews and contribute to the safety of surgical care in the intra-operative magnetic resonance imaging (MRI) suite.