Using computational fluid dynamics analysis to characterize local hemodynamic features of middle cerebral artery aneurysm rupture points.

OBJECTIVE: Although rupture of cerebral aneurysms typically occurs at the fragile wall at the apex or pole, some aneurysms rupture through the body or the neck. The purpose of this study was to clarify the association between aneurysm rupture points and hemodynamic features through the use of computational fluid dynamics (CFD) analysis. METHODS: Twelve ruptured middle cerebral artery bifurcation aneurysms were analyzed by 3-dimensional computed tomographic angiography and CFD. Rupture points were evaluated on intraoperative videos by 3 independent neurosurgeons. Wall shear stress (WSS) was calculated at the rupture point, aneurysm dome, and parent artery. Intra-aneurysmal flow patterns were evaluated with cross-sectional velocity vector planes that included the rupture points. RESULTS: The mean WSS at the rupture point (0.29 Pa) was significantly lower than that at the dome (2.27 Pa) and the parent artery (8.19 Pa) (P < .01). All rupture points were located within the area of WSS ≤ 11.2% of the WSS at the parent artery. WSS at the rupture point was correlated with the minimum WSS at the dome (r = 0.64, P < .05), but not with aneurysm size (r = 0.26) or the aspect ratio (r = 0.16). Flow patterns revealed that all rupture points were located in lower-velocity area, which was associated with complex flow patterns and/or deviating necks. CONCLUSIONS: This study highlights the relationship between the local hemodynamic features and the rupture points observed during the microsurgical clipping. CFD may determine a rupture point of aneurysms using the feature of markedly low WSS.

[On-the-street DOTS for a homeless tuberculosis patient--case report of a patient who had difficulties with TB treatment adherence].

PURPOSE: A homeless patient with tuberculosis (TB), who had often quit his TB treatment in mid-course and then gone homeless again, succeeded in completing his treatment for over 10 months through on-the-street DOTS ("Bluesky DOTS" is another expression). Based on the analysis of this case, we have discussed how to provide effective countermeasures to non-compliant TB patients. METHOD: An episode of a successful on-the-street DOTS for a 70-year-old homeless man with sputum smear positive pulmonary TB was qualitatively analyzed, with a view toward patient's empowerment. RESULT: The patient had had human-relations problems in his life, and trouble with medical and welfare service staff. During his hospital admissions, he repeatedly self-discharged or was forced to discharge due to violent behavior against staff. Public health nurses at Shinjuku public health center visited the patient frequently at the hospital, and tried to build a good relationship with the patient from the beginning of the treatment. Following a two and half month interruption of the TB treatment after he disappeared from the hospital, he was discovered staying outside at a canal side in the area, and on-the-street TB treatment was carried out, with good cooperation with the hospital and social welfare office. Directly observed TB medication was given to him by a public health nurse and another health center staff member for 293 days, at the park near his living place. The patient often rejected the medication, particularly when he was hungry, but offering lunch to him was a very effective incentive. Through comprehensive supports to the patient, he gradually changed his attitude, and on his own came to consider his health and his future. DISCUSSION: We have analyzed a successfully treated case of a homeless TB patient who had difficulties in maintaining a social life and had not been cooperative in complying with the medication. The level of independence improved during the course of on-the-street DOTS with incentive and other supports. He became receptive to TB treatment and became self-supportive during the course of DOTS, with food as an incentive. This indicates that on-the-street DOTS was successful not only for the treatment completion but also contributed to empowering the TB patient. This approach of adjusting the service to the patient's needs fostered a positive relationship with all stakeholders.

Changes in hemodynamics after placing intracranial stents.

Stent-assisted coil embolization has enabled the endovascular treatment of wide-necked cerebral aneurysms. Moreover, recent reports demonstrated that stent-assisted coil embolization was associated with a significant decrease in angiographic recurrences of coiled cerebral aneurysms. One of the possible explanations for this adjunctive effect of stent-assisted coil embolization is changes in the local hemodynamics caused by placing intracranial stents. This study investigated the hemodynamic effect of intracranial stents using computational fluid dynamics (CFD) analysis. The geometry of the intracranial stent, Enterprise(TM) VRD, was acquired by using micro computed tomography and virtually placed across the aneurysm orifice of a saccular aneurysm model (saccular model) and a blister-like aneurysm model (blister-like model) constructed from patient-specific three-dimensional (3D) rotational angiography data. Transient CFD analysis was performed with these models with and without stents. Stent placement induced no significant changes in the 3D streamline in the saccular model and slight changes in the blister-like model. Both saccular and blister-like models with stents had lower wall shear stress (WSS) and flow velocity, and higher oscillatory shear index, WSS gradient, and relative residence time than the equivalent models without stents, indicating the possibility that stent placement induced stagnant and disturbed blood flow. Cross-sectional vector velocity around the stent strut revealed complex blood flow patterns with variable direction and velocity. Although this study was a simulation under limited conditions, similar hemodynamic changes might be induced in the neck remnants treated with stent-assisted coil embolization.

Novel dynamic four-dimensional CT angiography revealing 2-type motions of cerebral arteries.

BACKGROUND AND PURPOSE: We developed a novel dynamic 4-dimensional CT angiography to accurately evaluate dynamics in cerebral aneurysm. METHODS: Dynamic 4-dimensional CT angiography achieved high-resolution 3-dimensional imaging with temporal resolution in a beating heart using dynamic scanning data sets reconstructed with a retrospective simulated R-R interval reconstruction algorithm. RESULTS: Movie artifacts disappeared on dynamic 4-dimensional CT angiography movies of 2 kinds of stationary phantoms (titanium clips and dry bone). In the virtual pulsating aneurysm model, pulsation on the dynamic 4-dimensional CT angiography movie resembled actual movement in terms of pulsation size. In a clinical study, dynamic 4-dimensional CT angiography showed 2-type motions: pulsation and anatomic positional changes of the cerebral artery. CONCLUSIONS: This newly developed 4-dimensional visualizing technique may deliver some clues to clarify the pathophysiology of cerebral aneurysms.

[Tuberculosis control in Shinjuku Ward, Tokyo--promoting the DOTS program and its outcome].

OBJECTIVES: The objectives were to report how to promote tuberculosis (TB) control including DOTS (Directly Observed Treatment, Short-course) programs, and to evaluate the results of TB control programs in Shinjuku Ward (Shinjuku-ku). SETTING AND CHARACTERISTICS: Inhabitants and TB patients in Shinjuku Ward. Shinjuku Ward is located in the center of metropolitan Tokyo and has typical urban TB problems, such as high incidence rate and TB among foreigners and the homeless. The TB incidence rates in Shinjuku Ward decreased from 83.9 per 100,000 population in 1999 to 42.5 per 100,000 population in 2006, however, the rates were still two times higher than the national average. Therefore, one of the important TB programs in Shinjuku has been to actively detect cases among high-risk groups such as foreigners and the homeless. METHODS: We observed the trend of case detection rates by health examination with chest X-ray among different high-risk groups, and compared the treatment outcomes before and after DOTS program execution. We also reviewed the changes of re-treatment rates and drug resistance rates. RESULTS: The case detection rates of TB by health examinations of foreign students at Japanese language schools decreased from 0.49% in 1996 to 0.13% in 2006 (p = 0.021). Although the case detection rates decreased, they were still about 26 times higher than those of Japanese students. While, the case detection rates among the homeless remained high with 4.7%, 3.3%, 4.5% and 3.6% in 1999-2002, respectively, since 2003, however, they had decreased and no TB cases were detected in 2005-2006. The DOTS program for homeless TB patients has been carried out since 2000 and that for the foreigners since 2003. The rates of defaulting during treatment before DOTS were very high among both homeless patients (21.4%) and foreigners (29.8%) in 1998-1999. However, after the introduction of DOTS program, those rates declined to 10.4% (p = 0.014) among the homeless and 7.8% (p = 0.002) among foreigners in 2002-2004. The proportion of newly notified patients with previous TB treatment and those with multi-drug resistant TB (MDR-TB) have also decreased after the introduction of DOTS programs. From 2000-2002 to 2003-2006, the re-treatment rates decreased from 19.4% to 10.0% (p < 0.001) and MDR-TB rates decreased from 1.6% to 0.2% (p = 0.042), respectively. DISCUSSION: The key points of TB control in Shinjuku Ward are to detect TB cases early especially among the high-risk groups, and to assist all TB patients to complete their treatment. In order to expand this strategy, besides promoting active case findings among high-risk groups, we have developed many types of DOTS programs, considering each patient's lifestyle and cooperating with school teachers at schools, pharmacists at pharmacies, home-care specialists at homes or facilities for the elderly, and so on. Among others, a major premise for the homeless and some other socially disadvantaged patients was to guarantee the provision of medicine and living by introducing social welfare services, before starting DOTS programs. This approach might have helped to reduce the defaulting rate, relapse rate and MDR-TB rate.

[Implementation and evaluation by a population-based RFLP analysis in an urban area, Shinjuku city, Tokyo--the possibility of application for contact investigations].

OBJECTIVES: The objectives were to examine Mycobacterium tuberculosis transmission patterns by RFLP analysis in Shinjuku city, and to elucidate more effective methods of contact investigations. METHODS: We applied RFLP analysis to 389 M. tuberculosis isolates from 402 TB patients registered in Shinjuku city from September 2002 though August 2006. RESULTS: Forty-six clusters consisting of 155 TB patients (average 3.4 people per cluster) were identified (proportion of clustering: 39.8%). The clustering rates were 34.5% among general patients, and 57.8% among homeless patients, and the latter was higher than that of non-homeless patients (odds ratio: 2.6, 95% CI; 1.6-4.1, p < 0.001). On the other hand, the clustering rates were only 19.4% among foreigners (odds ratio: 0.5, 95% CI; 0.2-1.2, p = 0.090). Twenty-eight of 46 clusters (60.9%) were consisted of mixture of general patients, homeless patients and foreigner patients. Thus, RFLP analysis can detect the transmission route which can not be identified by the routine contact examination, thus enabling contact investigations extended to the appropriate persons. DISCUSSION: The homeless clustering rate was significantly high. This suggests that the proportion of transmission among the homeless patients might be high. However, many clusters were composed of a mixture of homeless patients and non-homeless patients, so transmission patterns are not easy to identify. It is not always true that transmission of tuberculosis to non-homeless patients took place from homeless patients. Clustering rates among homeless patients are high, therefore taking countermeasures for the homeless patients is an effective way to prevent the spread of tuberculosis. Introduction of RFLP analysis is a practical epidemiological methodology to investigate the source of infection and transmission route of infection, and can be applied to contact investigations. If RFLP analysis can be applied in a larger area, yearly changes of notification rates and molecular epidemiological clustering rates will provide indices for preventive measures against tuberculosis.

Relationship between whole-blood interferon-gamma responses and the risk of active tuberculosis.

We have analyzed the relationship between the responses to the diagnostic method for Mycobacterium tuberculosis (Mtb) infection, QuantiFERON-TB Gold (QFT-G), and the risk of developing active tuberculosis (TB). Contacts under 42 years old who were exposed to a patient with infectious pulmonary TB were tested using QFT-G during an investigation. Among 172 contacts, 111 (64.5%) were QFT-G positive. All subjects were evaluated for active TB by chest X-ray examination and, if needed, by CT scan at the time of the QFT-G test and 39 were diagnosed with active TB based on radiological abnormalities consistent with TB. Of these, 35 (89.7%) were QFT-G positive. Statistically the geometric mean of interferon-gamma (IFN-gamma) production levels of the active TB group was significantly larger than that of the latent TB infection group (p=0.013). The results of the multivariate analysis clearly showed that a combined parameter of ESAT-6 and CFP-10 significantly contributes to disease risk for the infected subjects. Our results suggest that subjects with high levels of IFN-gamma production in response to either ESAT-6 and/or CFP-10 in the QFT-G test have a higher possibility of developing active TB than QFT-G positive subjects with lower levels of IFN-gamma.

[Application and problems of quantiFERON TB-2G for tuberculosis control programs--(1) tuberculosis outbreak in a Cram School].

OBJECTIVE: The purpose of this study was to evaluate the usefulness of the QuantiFERON TB-2G (QFT), which is a novel method of detecting tuberculosis (TB) infection, in a case of TB outbreak. SUBJECTS AND METHODS: The index case was a teacher of a cram school in which students received one-to-one lessons. Subjects of the contact investigation were 118 students, 28 teachers, and 47 guardians. At first tuberculin skin test (TST) and QFT were performed only on subjects under 40 years old, but subjects of QFT were extended to the other contacts later. RESULTS: The QFT positive rates for students (70.0%) and teachers (56.5%) proved to be high according to the first contact investigation. Total of 46 secondary TB cases have been detected during the past 15 months after the index case had diagnosed as TB. The secondary attack rate for students, teachers, and guardians was 24.6%, 42.9%, and 8.3%, respectively. Ninety-three contacts, who were QFT positive or intermediate, or strong TST reactors, were indicated for chemoprophylaxis. The restriction fragment length polymorphism (RFLP) patterns of isolates from eight patients were identical to those of an isolate from the index case. Both infection and attack rates among students tended to increase in proportion to the degree of exposure and the frequency of attendance to the school. The youngest among students who developed TB disease was 13 years old and the attack rates were about 30 to 50 percent between 15 and 33 years old. CONCLUSIONS: It was concluded that the QFT test was very useful for confirming the extent of transmission of TB and for motivating the candidates for chemoprophylaxis to accomplish treatment. However, the QFT test was not helpful for reducing the indication of chemoprophylaxis because the infection rates were very high in our case. Some epidemiological findings about the influence of age factor to the potential of progression to active TB in young people were obtained.

[A case of organized chronic subdural hematoma showing an early recurrence after craniotomy].

A 64-year-old man who had undergone single burr hole drainage twice prior to this admission was hospitalized with a recurrent right chronic subdural hematoma. A head CT showed a mixed density subdural hematoma on the right frontotemporoparietal region. Based on the intraoperative findings of the previous surgeries, the hematoma was known to be organized. Therefore, we decided to do a small craniotomy under general anesthesia, and remove the organized subdural hematoma and thick outer membrane while leaving the thickened dura matter intact. The inner membrane was left untouched. One week later, despite adequate decompression, the hematoma recurred with midline shift on head CT. It is likely that the uniquely thick and vascular enriched outer membrane and dura contributed to such an early recurrence. Finally, we performed an extensive craniotomy, removing all the organized hematoma, outer membrane and dura. Again, the inner membrane was left intact. On one year follow-up the patient has been asymptomatic with complete resolution of the subdural hematoma on CT scan. The successful treatment of organized chronic subdural hematoma can be challenging. We strongly recommend an extensive removal of the organized hematoma, outer membrane and excision of the dura mater in order to achieve a successful outcome after failed burr hole evacuation.