Prediction of spontaneous vaginal delivery in the prolonged second stage using the delta angle of progression.

BACKGROUND: It is clinically challenging to determine when to intervene in the prolonged second stage. Although individualized prediction of spontaneous vaginal delivery is crucial to avoid maternal and neonatal complications associated with operative deliveries, the approach has not been fully established. OBJECTIVE: We aimed to evaluate the predictability of spontaneous vaginal delivery using the difference in angle of progression between pushing and rest, delta angle of progression, to establish a novel method to predict spontaneous vaginal delivery during the prolonged second stage in nulliparous women with epidural anesthesia. STUDY DESIGN: We retrospectively analyzed deliveries of nulliparous women with epidural anesthesia between September 2018 and October 2023. Women were included if their delta angle of progression during the second stage was available. Operative deliveries were defined as the cases that required forceps, vacuum, and cesarean deliveries due to labor arrest. Women requiring operative deliveries due to fetal and maternal concerns, or women with fetal occiput posterior presentation were excluded. The second stage was stratified into the prolonged second stage, the period after 3 hours in the second stage, and the normal second stage, the period from the beginning until the third hour of the second stage. The association of the delta angle of the progression measured during each stage with spontaneous vaginal delivery and operative deliveries was investigated. Furthermore, the predictability of spontaneous vaginal delivery was evaluated by combining the delta and rest angle of progression. RESULTS: A total of 129 women were eligible for analysis. The delta angle of progression measured during the prolonged second stage and normal second stage were significantly larger in women who achieved spontaneous vaginal delivery compared to operative deliveries (p<.001 and p<.05, respectively). During the prolonged second stage, a cutoff of 18.8 derived from the receiver operative characteristic curves in the context of the delta angle of progression predicted the possibility of spontaneous vaginal delivery (sensitivity, 81.8%; specificity, 60.0%; AUC, 0.76). Combining the rest angle of progression (>140) and delta angle of progression (>18.8) also provided quantitative prediction of spontaneous vaginal delivery (sensitivity, 86.7%; specificity, 70.0%; AUC, 0.80). CONCLUSION: The delta angle of progression alone or in combination with the rest angle of progression can be used to predict spontaneous vaginal delivery in the second stage in nulliparous women with epidural anesthesia. Quantitative analysis of the effect of pushing using the delta angle of progression provides an objective guide to assist with an assessment of labor dystocia in the prolonged second stage on an individualized basis, which may optimize labor management in the prolonged second stage by reducing neonatal and maternal complications related to unnecessary operative deliveries and prolonged second stage of labor.

The head direction to the angle of progression ratio: a quantitative parameter for intrapartum evaluation of cephalic malposition.

BACKGROUND: No previous study has evaluated the transitions of intrapartum transperineal ultrasound parameters during labor progression in cephalic malposition. OBJECTIVE: We aimed to quantitate the characteristic trends of fetal head position and descent in cephalic malposition by analyzing the transitions of intrapartum transperineal ultrasound parameters and explore an indicator associated with the degree of cephalic malposition. STUDY DESIGN: We retrospectively analyzed pregnant women who delivered at term from January 2018 to December 2020 at the University of Tokyo Hospital. The fetal occipital position was classified as occiput anterior and nonocciput anterior according to the fetal occipital angle of 0° to 75° and 75° to 180°, respectively. Fetal occipital angle was defined by the midline angle and position of the ocular orbit. The differences in the trends of head direction, head-symphysis distance, and progression distance relative to the angle of progression between occiput anterior and nonocciput anterior cases were evaluated. In addition, the parameters that showed differences were analyzed to evaluate their relationship to the degree of cephalic malposition. RESULTS: A total of 502 images (occiput anterior, 319; nonocciput anterior, 183) met the inclusion criteria. The distribution of head direction values relative to the angle of progression was smaller in the nonocciput anterior group than in the occiput anterior group, whereas the head-symphysis distance and progression distance values relative to the angle of progression showed no difference in their distribution between the occiput anterior and nonocciput anterior groups. The ratio of head direction to the angle of progression was significantly smaller in the nonocciput anterior group than in the occiput anterior group (median [interquartile range], 0.03 [-0.02 to 0.10] vs 0.21 [0.12-0.28]; P<.0001). Furthermore, this ratio was negatively correlated with fetal occipital angle (Spearman correlation coefficient, -0.66). CONCLUSION: Our results indicated that the head direction to angle of progression ratio reflects the deviation in the fetal head direction toward the maternal dorsal side, and decreases in proportion to the degree of cephalic malposition. This concept of deviation in the head direction as an indicator for evaluating cephalic malposition with intrapartum transperineal ultrasound may contribute to improving labor management in the case of cephalic malposition.

A Parametric Study of Flushing Conditions for Improvement of Angioscopy Visibility.

During an angioscopy operation, a transparent liquid called dextran is sprayed out from a catheter to flush the blood away from the space between the camera and target. Medical doctors usually inject dextran at a constant flow rate. However, they often cannot obtain clear angioscopy visibility because the flushing out of the blood is insufficient. Good flushing conditions producing clear angioscopy visibility will increase the rate of success of angioscopy operations. This study aimed to determine a way to improve the clarity for angioscopy under different values for the parameters of the injection waveform, endoscope position, and catheter angle. We also determined the effect of a stepwise waveform for injecting the dextran only during systole while synchronizing the waveform to the cardiac cycle. To evaluate the visibility of the blood-vessel walls, we performed a computational fluid dynamics (CFD) simulation and calculated the visible area ratio (VAR), representing the ratio of the visible wall area to the total area of the wall at each point in time. Additionally, the normalized integration of the VAR called the area ratio (ARVAR) represents the ratio of the visible wall area as a function of the dextran injection period. The results demonstrate that the ARVAR with a stepped waveform, bottom endoscope, and three-degree-angle catheter results in the highest visibility, around 25 times larger than that under the control conditions: a constant waveform, a center endoscope, and 0 degrees. This set of conditions can improve angioscopy visibility.

Prenatal diagnosis of pyriform sinus fistula using ultrasonography by detecting the communication to the pharynx.

OBJECTIVE: Pyriform sinus fistula (PSF) is a congenital anomaly which originates from the pharyngeal pouch. PSF is initially recognized as a cyst around the fetal neck, but accurate prenatal diagnosis of the disease is challenging. We aimed to report the key findings and tips in accurately distinguishing PSF from other differential diagnosis by which enables detection of the communication of the nuchal cyst and the pharynx. CASE REPORT: We report a case in which we were able to diagnose PSF as early as 18 weeks of gestation with ultrasonography. We used epiglottis as a landmark, and detected an unilobular cyst arising from the pharynx. CONCLUSION: Ultrasonography is a powerful tool in prenatal diagnosis of PSF especially at early stage of pregnancy. By detecting the epiglottis, it can locate the communication of the nuchal cyst and the pharynx, and thereby enables an accurate diagnosis of PSF.

Thermokeratoplasty for Keratoconus: A More Than 30-Year Follow-Up Study.

PURPOSE: The aim of this study was to investigate the long-term outcomes of thermokeratoplasty (TKP) surgery in patients with keratoconus (KC). METHODS: We retrospectively reviewed our clinical database of 2949 patients with KC seen at the Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan, between April 1979 and December 1991. Patients with KC who underwent TKP with a greater-than 30-year postoperative follow-up were included. The occurrence of adverse events including infectious keratitis, corneal perforation, corneal melting, bullous keratopathy, consistency of contact lenses (CL) wear at the final visit, and a history of corneal transplantation post-TKP was assessed. RESULTS: Forty-two patients (29 male and 13 female patients) with a mean age at initial visit of 23.4 years (range: 13.9-39.5 yrs) were included, and TKP was performed unilaterally in all cases. The mean follow-up period was 35.2 years (range: 30.1-41.6 yrs). As for adverse events/complications, no cases of infectious keratitis, corneal perforation, corneal melting, and/or BK were observed. However, 11 eyes received corneal transplants at an average of 24.9 years postoperatively because of the inability to wear CL continuously. At the last visit, 31 eyes were able to continue wearing CL without corneal transplantation, and the remaining 11 eyes were able to continue wearing contact lenses in all cases after corneal transplantation. CONCLUSIONS: TKP for KC resulted in relatively favorable surgical outcomes over the long-term postoperative period.

Flush Flow Behaviour Affected by the Morphology of Intravascular Endoscope: A Numerical Simulation and Experimental Study.

Background: Whilst intravascular endoscopy can be used to identify lesions and assess the deployment of endovascular devices, it requires temporary blockage of the local blood flow during observation, posing a serious risk of ischaemia. Objective: To aid the design of a novel flow-blockage-free intravascular endoscope, we explored changes in the haemodynamic behaviour of the flush flow with respect to the flow injection speed and the system design. Methods: We first constructed the computational models for three candidate endoscope designs (i.e., Model A, B, and C). Using each of the three endoscopes, flow patterns in the target vessels (straight, bent, and twisted) under three different sets of boundary conditions (i.e., injection speed of the flush flow and the background blood flowrate) were then resolved through use of computational fluid dynamics and in vitro flow experiments. The design of endoscope and its optimal operating condition were evaluated in terms of the volume fraction within the vascular segment of interest, as well as the percentage of high-volume-fraction area (PHVFA) corresponding to three cross-sectional planes distal to the microcatheter tip. Results: With a mild narrowing at the endoscope neck, Model B exhibited the highest PHVFA, irrespective of location of the cross-sectional plane, compared with Models A and C which, respectively, had no narrowing and a moderate narrowing. The greatest difference in the PHVFA between the three models was observed on the cross-sectional plane 2 mm distal to the tip of the microcatheter (Model B: 33% vs. Model A: 18%). The background blood flowrate was found to have a strong impact on the resulting volume fraction of the flush flow close to the vascular wall, with the greatest difference being 44% (Model A). Conclusion: We found that the haemodynamic performance of endoscope Model B outperformed that of Models A and C, as it generated a flush flow that occupied the largest volume within the vascular segment of interest, suggesting that the endoscope design with a diameter narrowing of 30% at the endoscope neck might yield images of a better quality.

Initial national investigation of the prenatal diagnosis of congenital heart malformations in Japan-Regional Detection Rate and Emergency Transfer from 2013 to 2017.

BACKGROUND: Investigation into the detection rate (DR) of congenital heart diseases (CHDs) in fetuses is important for the assessment of fetal cardiac screening systems. OBJECTIVES: We highlight issues of fetal cardiac screening in Japan. METHODS: We performed an initial national survey of fetal diagnosis of CHDs from the data of the national registry for congenital heart surgery from 2013 to 2017. Subjects were neonates and infants with moderate or severe CHDs. We investigated DR in each prefecture in Japan and emergency transfer (ET) for neonates by analyzing distance and admission day of ET with or without fetal diagnoses. RESULTS: The overall average DR in Japan was 0.41 (0.02 increase every year). No regional significant relationship was found between DR and population in each prefecture. ET was performed in 12% of neonates with prenatal diagnosis and in 63% of neonates without resulting in significant risk for ET in fetuses without a fetal diagnosis [OR 13.3 (11.6-15.3), p<0.001]. The distance of ET was shorter and admission was earlier in the neonates with a prenatal diagnosis than in those without [median 6.6 km (IQR: 4.1-25.7) vs 17.0 km (IQR: 7.4-35.3), median 0.0 day (IQR: 0.0-0.0) vs 0.0 day (IQR: 0.0-1.0), p<0.001, p<0.001, respectively] CONCLUSIONS: Prenatal cardiac diagnosis reduces geographic and chronological risks of ET for moderate to severe CHDs. DR is still developing and periodic official surveillance is required for improving prenatal cardiac diagnosis in Japan.

Ultrasonographic vascularity assessment for predicting future severe hemorrhage in retained products of conception after second-trimester abortion.

Objectives: To investigate the spontaneous outcomes of vascularized retained products of conception (RPOC) detected by ultrasonography after second-trimester abortion, and to identify the predictive factors for the development of severe postpartum hemorrhage (SPPH).Study design: This is a retrospective cohort study on all cases after second-trimester abortion managed at our institute between January 2014 and December 2016. We assessed the associations between the occurrence of SPPH requiring invasive treatment and clinical factors including ultrasonographic findings (size and the vascularity status of RPOC classified as follows: type 1: vascularity confined to endometrium, type 2: vascularity reaching <1/2 myometrium, and type 3: vascularity reaching ≥1/2 myometrium) in vascularized RPOC cases.Results: Among 103 cases after second-trimester abortion, 19 patients (18.4%) were diagnosed as RPOC, and five patients eventually failed expectant management due to SPPH. Of them, 66.7% (4/6) of patients with type 3 developed SPPH as compared with 7.7% (1/13) of patients with type 1/type 2 (p < .05). The maximum vascularized mass diameter was significantly greater among the five patients who experienced SPPH than among the 14 patients who demonstrated spontaneous remission (43.0 ± 12.0 mm versus 20.7 ± 8.3 mm, p < .01). Patients with type 3 RPOC and a maximum vascularized mass diameter ≥30 mm, compared with other patients, demonstrated sensitivity, specificity, and risk ratio related to SPPH of 80, 92.9%, and 11.2, respectively.Conclusions: Our findings suggest that the ultrasonographic assessment of RPOC focused on the depth of vascularity in combination with the measurement of its size appears to be essential in determining women with RPOC who are at high risk for SPPH.

Polyhydramnios is associated with postnatal dysphagia determining short-term prognosis of the newborn with 22q11.2 deletion syndrome - A case series analysis.

OBJECTIVE: We experienced a case of 22q11.2 deletion syndrome (22qDS), with severe polyhydramnios, and dysphagia, which prompted us to review prognosis in neonates with 22qDS, with a focus on dysphagia. CASE REPORT: A patient was referred to our hospital at 35 gestational weeks because of polyhydramnios. After amniotic fluid reduction, labor was induced at 38 weeks. The neonate had serious dysphagia, and 22qDS was diagnosed postnatally by fluorescent in situ hybridization analysis. This prompted a retrospective analysis of 9 cases with 22qDS experienced in our facility. Three out of these nine cases showed polyhydramnios, and had severe dysphagia postnatally. In total, 4 cases had dysphagia, while mortality was observed in 2 of these 4 cases. Additionally, 5 cases without dysphagia had normal development and no major complications. CONCLUSION: Polyhydramnios associated with postnatal dysphagia might be a risk factor related to short-term prognostic outcomes in newborns with 22qDS.

Abdominal compartment syndrome complicated by preeclampsia and partial HELLP syndrome in a 45-year-old woman: A case report.

HELLP syndrome is sometimes followed by massive bleeding, leading to DIC. In cases of intra-abdominal compartment syndrome due to massive intra-abdominal bleeding after cesarean section, if preeclampsia and partial HELLP syndrome persist, hematoma removal helps in the recovery from preeclampsia and partial HELLP syndrome.

Impact of additional risk factors on the incidence of preterm delivery among pregnant women diagnosed with short cervix.

OBJECTIVE: Additional risk factors for preterm delivery in pregnant women with cervical shortening are not fully understood; however, mid-trimester cervical shortening is accepted as a risk factor for preterm delivery. This study aimed to identify risk factors associated with subsequent preterm delivery among patients with short cervix detected after late mid-trimester. MATERIALS AND METHODS: This was a retrospective study of medical data from a single perinatal tertiary facility. We identified 134 asymptomatic women with singleton pregnancies where cervical shortening (≤25 mm) was detected during routine universal screening at 22-33 weeks. Statistical analyses were conducted to identify causal relationships between the incidence of preterm delivery and known risk factors for preterm delivery. RESULTS: Incidence of preterm delivery was 27.6% (37/134) and preterm premature rupture of membrane was preceded in 46.0% (17/37) of the women with preterm delivery. Using logistic regression analysis, we identified uterine contractions [aOR 4.25, 95% confidence intervals (CI):1.68-12.1] and increased C-reactive protein (CRP) and increased white blood cell (WBC) in blood test (CRP: aOR 3.45, 95% CI:1.50-9.71; WBC: aOR 1.28, 95% CI: 1.08-1.55) as risk factors which significantly increased the risk of preterm delivery among women diagnosed with short cervix. Preterm delivery occurred in 91% of women positive for both uterine contractions and CRP >0.5 mg/dl. CONCLUSIONS: Uterine contraction and elevated CRP were additional risk factors for preterm delivery among women with short cervix. These results might be clinically useful to evaluate subsequent risk for preterm delivery in asymptomatic pregnant women presenting with short cervix in mid-pregnancy.

Management of a pregnant woman with hypouricemia: a case report.

Renal hypouricemia is associated with urinary calculi and severe acute renal failure after exercise. The epidemiology of renal hypouricemia is not yet sufficiently understood, and there is no report of it occurring during pregnancy. We report the case of a pregnant woman with renal hypouricemia. At her first pregnancy, she developed preeclampsia with severe features at the 34th week of gestation. After parturition, she developed acute renal failure and was diagnosed with renal hypouricemia. During the second pregnancy, when she was referred to our hospital, care was taken to ensure adequate hydration by infusion of liquids and water at the time of labour. Consequently, she did not have onset of renal hypouricemia. We suggest that acute renal failure may be avoided in pregnant women with renal hypouricemia by preventing dehydration via drinking enough during pregnancy postpartum period and by infusion during labour.

Elevation of maternal serum sFlt-1 in pregnancy with mirror syndrome caused by fetal cardiac failure.

Mirror syndrome (MS) is characterized by the combination of maternal generalized edema, fetal hydrops and placental hypertrophy. A shift of the serum placenta-derived angiogenic factor like sFlt-1 in MS is similar to that in pre-eclampsia (PE). We experienced a MS case caused by cardiac myopathy in the fetus with normal cardiac structure. A 27-year-old primiparous woman at 28 weeks of gestation had systemic edema without hypertension and proteinuria. Her symptoms rapidly disappeared after delivery. Compared with previously reported MS cases with maternal hypertension or proteinuria, the serum sFlt-1 level was lower in our case. Severity of maternal symptoms in MS might be paralleled with the serum sFlt-1 level. Additionally, serum hCG level in MS is much higher than that in PE. Maternal edema rather than hypertension and proteinuria can be more remarkable in MS compared with PE. It can be potentially explained by increased serum hCG level.

Adenomyosis and adverse perinatal outcomes: increased risk of second trimester miscarriage, preeclampsia, and placental malposition.

OBJECTIVE: To evaluate the potential impact of adenomyosis on the pregnancy outcomes by retrospectively investigating adenomyosis-complicated pregnancy cases. METHODS: We performed a retrospective case-control study. Forty-nine singleton pregnancy cases complicated with adenomyosis were included in this study. The controls (n = 245) were singleton pregnant women without adenomyosis and were frequency matched to adenomyosis cases by age, parity, and the need for assisted reproductive technology for this conception. The incidence of obstetrical complications and delivery and neonatal outcomes were examined. RESULTS: Patients in the adenomyosis group were significantly more likely to have a second trimester miscarriage (12.2% versus 1.2%, odds ratio (OR): 11.2, 95% confidence interval (95% CI): 2.2-71.2), preeclampsia (18.3% versus 1.2%, OR: 21.0, 95% CI: 4.8-124.5), placental malposition (14.2% versus 3.2%, OR: 4.9, 95% CI: 1.4-16.3), and preterm delivery (24.4% versus 9.3%, OR: 3.1, 95% CI: 1.2-7.2), compared with the control group. CONCLUSION: Adenomyosis was associated not only with an increased incidence of preterm delivery, as previously reported, but also with an increased risk of second trimester miscarriage, preeclampsia, and placental malposition, which could lead to poor perinatal outcomes.

A case of a surviving co-twin diagnosed with porencephaly and renal hypoplasia after a single intrauterine fetal death at 21 weeks of gestation in a monochorionic monoamniotic twin pregnancy.

Monochorionic monoamniotic (MM) twin pregnancy carries a high risk of intrauterine fetal death (IUFD). Single IUFD in an MM twin pregnancy prior to 22 weeks of gestation has been reported to be strongly correlated with double twin demise. To our knowledge, there are no case reports on the natural course of a surviving co-twin in an MM twin pregnancy resulting in live birth after a single IUFD prior to 22 weeks of gestation. Here, we report a case of a surviving co-twin, after a single IUFD at 21 weeks of gestation in a MM twin pregnancy, with an antenatal diagnosis of renal hypoplasia and severe neurological damage leading to porencephaly, and live birth at 36 weeks of gestation.

Daughter Sac Formation Related to Blood Inflow Jet in an Intracranial Aneurysm.

OBJECTIVE: We performed a hemodynamic study of an intracranial aneurysm with a newly developed daughter sac during observation to investigate the role of hemodynamics on the formation of a daughter sac. METHODS: A 75-year-old man underwent magnetic resonance angiography that revealed a large internal carotid artery aneurysm with inflow jet inside the aneurysm. The aneurysm was stable for 18 months, but a new daughter sac developed at the tip of the aneurysm during the next 6 months. The daughter sac seemed to be related to the inflow jet on magnetic resonance angiography. Aneurysm geometries before and after daughter sac formation were reconstructed using the longitudinal data of magnetic resonance angiography. Computational fluid dynamic simulations were conducted under the patient-specific pulsatile inlet conditions measured by magnetic resonance velocimetry. RESULTS: The hemodynamic simulation revealed that the inflow jet impinged on 2 sites of the aneurysm: the right side of the aneurysmal dome and the tip of the aneurysm. The flow impingement caused elevation of pressure at both sites. However, the daughter sac formed at the latter site surrounded by the basal cistern but did not form at the former site that was in contact with the right temporal lobe. CONCLUSIONS: Blood inflow jet caused local elevation of pressure, and the formation of the daughter sac occurred at the site with high pressure but without the surrounding structure, which may cancel the perpendicular wall tension.

Elevated concentration of secretory leukocyte protease inhibitor in the cervical mucus before delivery.

BACKGROUND: Cervical remodeling during parturition progresses under exquisite regulation by immunologic mediators and proteases. Secretory leukocyte protease inhibitor is a secretory protein that can function as an antimicrobial peptide, an antiinflammatory molecule, and a protease inhibitor. The involvement of secretory leukocyte protease inhibitor in cervical remodeling before and during parturition is understood poorly. OBJECTIVE: We aimed to reveal the role of secretory leukocyte protease inhibitor in the cervical remodeling process before normal term delivery and to evaluate its utility as a predictive biomarker for timing of delivery. STUDY DESIGN: Cervical mucus samples were collected prospectively at weekly prenatal visits from a cohort of pregnant women at term. The secretory leukocyte protease inhibitor concentrations in 95 mucus samples that were obtained from 49 women with uncomplicated pregnancy who subsequently underwent normal vaginal delivery were assessed. Alterations in secretory leukocyte protease inhibitor concentrations at term and the association of secretory leukocyte protease inhibitor levels with the time to delivery were analyzed. RESULTS: A moderate positive correlation with significance was detected between cervical mucus secretory leukocyte protease inhibitor concentrations and days to delivery (r = 0.38; P = .0001). The secretory leukocyte protease inhibitor concentration was significantly higher in samples that were collected within 7 days of delivery when compared with samples that were collected >7 days before delivery (P = .001). Secretory leukocyte protease inhibitor concentrations were also significantly higher in samples from women with premature rupture of membranes when compared with those without premature rupture of membranes (P = .01), all of whom delivered within 7 days. A logistic regression analysis revealed that the cervical secretory leukocyte protease inhibitor level was a significant parameter for the prediction of the onset of delivery. (P = .017; unit odds ratio, 1.28; 95% confidence interval, 1.07-1.61). A cut-off value of cervical secretory leukocyte protease inhibitor/total protein to predict delivery within 7 days was determined to be 1.62 µg/mg (sensitivity, 0.69; specificity, 0.72) using receiver operating characteristic curve-analysis. CONCLUSION: Secretory leukocyte protease inhibitor concentrations in the cervical mucus elevate progressively before delivery in uncomplicated term pregnancies. Our findings suggest that cervical secretory leukocyte protease inhibitor is a candidate biomarker for delivery prediction.

Relative residence time prolongation in intracranial aneurysms: a possible association with atherosclerosis.

BACKGROUND: Intracranial aneurysms can have atherosclerotic wall properties that may be important in predicting aneurysm history or estimating the potential risks of surgical treatments. OBJECTIVE: To investigate hemodynamic characteristics of atherosclerotic lesions in intracranial aneurysms using computational fluid dynamics. METHODS: Intraoperative video recordings of 30 consecutive patients with an unruptured middle cerebral artery aneurysm were examined to identify atherosclerotic lesions on an aneurysm wall. For computational fluid dynamics analyses, geometries of aneurysms and adjacent arteries were reconstructed from 3-dimensional rotational angiography. Transient simulations were conducted under patient-specific pulsatile inlet conditions measured by phase-contrast magnetic resonance velocimetry. Three hemodynamic wall parameters were calculated: time-averaged wall shear stress, oscillatory shear index, and relative residence time (RRT). Statistical analyses were performed to discriminate the risk factors of atherosclerotic lesion formation. RESULTS: Among 30 aneurysms, 7 atherosclerotic lesions with remarkable yellow lipid deposition were identified in 5 aneurysms. All 7 atherosclerotic lesions spatially agreed with the area with prolonged RRT. Univariate analysis revealed that male sex (P = .03), cigarette smoking (P = .047), and maximum RRT (P = .02) are significantly related to atherosclerotic lesion on the intracranial aneurysmal wall. Of those variables that influenced atherosclerotic lesion of the intracranial aneurysmal wall, male sex (P = .005) and maximum RRT (P = .004) remained significant in the multivariate regression model. CONCLUSION: The area with prolonged RRT colocalized with atherosclerotic change on the aneurysm wall. Male sex and maximum RRT were independent risk factors for atherogenesis in intracranial aneurysms.

Computational simulation of convection-enhanced drug delivery in the non-human primate brainstem: a simple model predicting the drug distribution.

OBJECTIVES: Convection-enhanced delivery (CED) is a technique that delivers therapeutic agents directly and effectively into the brain parenchyma. Application of CED is now under investigation as a new treatment for various diseases. Diffuse brainstem glioma is one of the important candidates that could be targeted with CED. Especially when targeting brainstem lesions, prediction of drug distribution prior to CED will be necessary. This study evaluated the computational simulation of CED in the primate brainstem using a simplified model. METHODS: Three in vivo experiments infusing gadolinium solution into the non-human primate brainstem were analyzed. T1-weighted magnetic resonance (MR) images were acquired during infusion of a total of 300 µl gadolinium solution. Computational simulation reconstructed the surface geometry of the brainstem from the MR images. The volume of the whole structure was meshed by grid generating software. Under the assumptions that the brainstem surface was rigid and the interior was filled with cerebrospinal fluid, the equations of continuity and Darcy's law were solved within a computational fluid dynamics package using a finite volume method. The results of computational simulations were compared with those of the in vivo experiments. RESULTS: The distribution volume (Vd) in the simulations corresponded well with the in vivo experiments. Under the condition without massive 'catheter back flow', computational simulations predicted almost 70% of the Vd of the in vivo experiments. CONCLUSIONS: The simplified computational simulations were consistent with the experiments in vivo. The methodology used in this study can be applied to predict convective drug distribution in the primate brainstem.