An inter-observer assessment of mastoid pneumatization and degree classification using sigmoid sinus: comparing two levels of temporal bone computed tomograms.

BACKGROUND: The degree of mastoid pneumatization of the temporal bone (TB) has been implicated in the pathogenesis of TB diseases and surgical implications, and planning of a few otologic surgeries. However, there is lack of consensus in the classification of the degree of pneumatization. This study aimed to suggest a simple, quick, and less-burden classification system for assessing and rating the degree of pneumatization by comparing two levels of TB computed tomographs (CTs) using the SS as a reference in an inter-observer assessment among otologists. METHODS: This was a randomized pilot survey among otologists. A questionnaire consisting of different axial CTs of TB taken at two levels: the level of malleoincudal junction (MIJ) and the level of lateral semicircular canal (LSCC), with different pneumatization patterns, was used to assess participants' impressions of the degree of pneumatization. The terms "hypo-," "moderate," "good," and "hyper-" pneumatization were listed as options to rate their impressions on the degree of mastoid pneumatization of the TB images using the SS as a reference structure. Likert scale was used to assess their level of agreement or disagreement with using SS as a reference in evaluating mastoid pneumatization. RESULTS: Participants who correctly rated images taken at the level of LSCC according to their respective degree of pneumatization were significantly higher (p < 0.05) regardless of their year of experience compared to those that correctly rated corresponding images taken at the level of MIJ. A 76% positivity in their level of agreement with the use of sigmoid sinus in evaluating mastoid pneumatization was observed on the Likert-scale chart. CONCLUSION: Findings from this study suggest that evaluating air cells around the SS at the level of LSCC on CTs could be easier in assessing and classifying the degree of mastoid pneumatization.

Combined Conduit Score in Contrast-Enhanced Magnetic Resonance Venography in Patients with Idiopathic Intracranial Hypertension : Neuro-interventionalists' vs. Radiologists' Assessment.

BACKGROUND: Based on increased understanding of the idiopathic intracranial hypertension (IIH) pathophysiology, venous sinus stenting (VSS) has emerged as an effective treatment for patients with transverse sinus stenosis (TSS). The presence of a reliable TSS screening tool is warranted. The combined conduit score (CCS) is the most widely used score for evaluation of the cerebral sinovenous stenosis in contrast-enhanced magnetic resonance venography (CE-MRV). PURPOSE OF THE STUDY: To evaluate the interobserver agreement between neuro-interventionalists and radiologists with respect to the CCS in evaluation of transverse sinus stenosis in patients with idiopathic intracranial hypertension using CE-MRV. METHODS: A retrospective study was conducted on 26 consecutive patients diagnosed with IIH and underwent CE-MRV. The 2 neuro-interventionalists and 2 radiologists separately evaluated the cerebral venous sinuses using the CCS. RESULTS: The mean CCS was significantly different between the neuro-interventionalists and radiologists (p < 0.001), higher for the radiologists. The inter-rater reliability was excellent (ICC = 0.954, 95% CI: 0.898-0.979) between the 2 neuro-interventionalists, good between the 2 radiologists (ICC = 0.805, 95% CI: 0.418-0.921), but was not acceptable between the neuro-interventionalists and the radiologists (ICC 0.47 95% CI:-2.2-0.782). CONCLUSION: Despite the excellent agreement between the neuro-interventionists and the good agreement between the radiologists, there was no agreement between the neuro-interventionists and the radiologists. Our finding suggests that there is a gap between the 2 specialties but does not favor any of them. Factors related to the observers, the venous sinus system, the MRV or the CCS score may have resulted in this discrepancy. Automatic or semi-automatic feature extractions to produce quantifiable biomarkers for IIH are warranted. The clinical decisions should not depend only on strongly observer-dependent scores with training and/or experience-dependent influences.

Preoperative assessment of dominant occipital sinus in patients with Chiari malformation type I: anatomical variations and implications for preventing potentially life-threatening surgical complications.

OBJECTIVE: The surgical treatment of Chiari malformation type I (CM-I) frequently involves dural incision at the posterior cranial fossa. In cases of persistent patent occipital sinus (OS), the sinus is usually obliterated and divided. However, there are some patients whose OS is prominent and requires crucial modification of the operative planning to avoid potentially life-threatening massive hemorrhage and disturbance of cerebral venous circulation. In the present study, the anatomical variations of the dominant OS in patients with CM-I were analyzed and the authors attempted to develop treatment recommendations for patients with CM-I with dominant OS. METHODS: The study included 213 patients with CM-I who underwent MR venography (MRV) prior to surgical treatment. OS dominance was assessed using 2D time-of-flight MRV or 3D phase-contrast MRV. Particular attention was paid to the pattern of venous outflow channels. The characteristics of the patients with dominant OS and the surgical outcomes were retrospectively reviewed. RESULTS: Dominant OS was identified in 7 patients (3.3%). The age in those with dominant OS was significantly younger than in those without (p = 0.0202). The incidence of concurrent scoliosis in the patients with dominant OS was significantly higher than in those without (p = 0.0366). All the dominant OSs were found to be of the oblique type. Unilateral oblique OS (OOS) with normal ipsilateral transverse sinus (TS) and hypoplastic contralateral TS was found in 2 patients (0.9%). The authors found 1 patient each (0.5%) who had unilateral OOS with hypoplastic ipsilateral TS and normal contralateral TS, unilateral OOS with bilateral hypoplastic TSs, and bilateral OOSs with bilateral normal TSs. Bilateral OOSs with bilateral hypoplastic TSs were found in 2 patients (0.9%). All these patients had syringomyelia. Instead of performing Y-shaped dural incision and duraplasty, surgical procedures were modified depending on the types of the OOSs to preserve their venous drainage routes. Although massive bleeding from the dominant OS during dural incision occurred in 1 patient, none suffered neurological deterioration. The syrinx volume decreased in all but 1 of the patients postoperatively. CONCLUSIONS: Assessment of the venous drainage pattern using MRV is indispensable for safe surgical treatment in patients with CM-I. The surgical procedure should be modified based on the type of dominant OS to minimize the surgical risks.

Prevalence, Surgical Management, and Audiologic Impact of Sigmoid Sinus Dehiscence Causing Pulsatile Tinnitus.

OBJECTIVE: To evaluate the prevalence, surgical management, and audiologic impact of pulsatile tinnitus caused by sigmoid sinus dehiscence. STUDY DESIGN AND SETTING: Retrospective chart review at a tertiary care hospital. PATIENTS: Adults with unilateral pulsatile tinnitus attributable to sigmoid sinus dehiscence who underwent resurfacing between January 2010 and January 2020. INTERVENTIONS: Transmastoid sigmoid resurfacing. MAIN OUTCOME MEASURES: Resolution of pulsatile tinnitus; audiologic outcomes; complications; tinnitus etiologies. RESULTS: Nineteen patients (89.4% women) had surgery for suspected sigmoid sinus dehiscence. The mean dehiscence size was 6.1 mm (range, 1-10.7 mm). Eight patients had concurrent sigmoid sinus diverticulum and one patient also had jugular bulb dehiscence. Only two patients (10.5%) had the defect identified by radiology. Low-frequency pure-tone average, measured at frequencies of 250 and 500 Hz, showed a significant median improvement of 8.8 dB following resurfacing (18.8 dB versus 10.0 dB, p = 0.02). The majority of patients had complete resolution of pulsatile tinnitus (16/19, 84.2%). Of those without complete resolution, two patients had partial response and one patient had no improvement. There were no significant complications. Of 41 consecutively tracked patients with a pulsatile tinnitus chief complaint, sigmoid pathology represented 32% of cases. CONCLUSIONS: Sigmoid sinus dehiscence represents a common vascular cause of pulsatile tinnitus that, if properly assessed, may be amenable to surgical intervention. Sigmoid sinus resurfacing is safe, does not require decompression, and may improve low-frequency hearing. Radiographic findings of dehiscence are often overlooked without a high index of clinical suspicion. Its relationship with transverse sinus pathology and idiopathic intracranial hypertension remain unclear.

Prenatal visualisation of the torcular herophili by means of a Doppler technology highly sensitive for low-velocity flow in the expert assessment of the posterior fossa: a prospective study.

OBJECTIVE: To evaluate the usefulness of a Doppler technology highly sensitive for low-velocity flow in the antenatal imaging of the torcular herophili (TH) in the second trimester of pregnancy. DESIGN: Prospective study. SETTING: Referral Fetal Medicine Unit. POPULATION: Non-consecutive series of singleton pregnancies submitted to antenatal neurosonogram between 20 and 28 weeks of gestation. METHODS: A midsagittal section of the fetal brain was obtained by insonating through the anterior fontanelle, then the MV-Flow™ and LumiFlow™ presets were selected to visualise the TH as the posterior confluence of the superior sagittal sinus and the straight sinus. MAIN OUTCOME MEASURES: Evaluation of the anatomic relationship of the TH with the 'transpalatal line' joining the upper bony palate to the fetal skull. RESULTS: A total of 99 pregnant women were recruited, including one fetus with open spina bifida, one with Dandy-Walker malformation (DWM) and two with Blake's pouch cysts. In normal fetuses, the TH appeared to lie on or just below the 'transpalatal line'. In the cases of Blake's pouch cyst, the position of the TH appeared normal if compared with controls, whereas in DWM a supra-elevated position of the TH in respect of the transpalatal line was demonstrated. Finally, in the fetus with Chiari II malformation the TH was identified below the 'transpalatal plane'. CONCLUSIONS: Prenatal ultrasound visualisation of the TH by means of newly developed Doppler technologies characterised by high sensitivity for low-velocity flow is feasible and allows the indirect evaluation of the insertion of cerebellar tentorium in the second trimester. TWEETABLE ABSTRACT: Prenatal imaging of the torcular herophili using a Doppler technology highly sensitive for low-velocity flow.

[Assessment of computed tomographic angiographysinus development combined with occipitalbone marks for the location of transverse sigmoid sinus junction].

Objective: To introduce and evaluate a technique to precisely localize the transverse-sigmoid sinus junction (TSSJ) in retrosigmoid craniotomy. Methods: This was a single-center prospective randomized controlled study. Sixty-three patients, 29 male and 34 female, who would undergo retrosigmoid craniotomy admitted to Department of Neurosurgery, the First Affiliated Hospital of Xinjiang Medical Universityfrom March to October 2019 were enrolled in the study and were divided into trial group and control group according to the computer-generated random numbers. Preoperative venous computed tomographic angiography (CTA) combined with 3-dimensional computed tomography computed tomography (3D CT) was randomly given to the patients(n=32). Asterion was used for identification of the TSSJ in the controls (n=31). The main outcome measures as postoperative complications and relevant intraoperative indicators were compared. Results: Incision length, craniotomy time, bone window sizein trial group were shorter or smaller than those of the controls, as(6.8±0.5) cm vs (8.0±1.5) cm, (37±8) min vs (45±15) min, (8.7±1.2) cm(2) vs (10.2±2.4) cm(2) respectively, with statistical significance (all P<0.05). No statistical significance was found in bleeding amount, incidence of sinus injury and cerebrospinal fluid leakage. While incidence of neck pain was lower in case group (15.63% vs 38.71%; P=0.04) and the remission time of incisional pain in case group was shorter [(6±1) d vs (9±2) d; P=0.01]. Conclusion: While the technique is used, the center of the keyhole should be located at transitional place of the lateral part of the occipitomastoid suture, the retromastoid ridge and the superior nuchal line. Compared with the traditional craniotomy method marked by asterion, it has great advantages in reducing incidence of postoperative complications, craniotomy time, and the remission time of incisional pain.

Preoperative risk assessment for predicting the opening of mastoid air cells in lateral suboccipital craniotomy for microvascular decompression.

OBJECTIVE: Opening of mastoid air cells (MACs), a complication of lateral suboccipital craniotomy for microvascular decompression (MVD), might cause cerebrospinal fluid (CSF) leakage and meningitis. Only a few studies have investigated the association of degree of MAC development and actual opening of MACs. The present study focused on preoperative risk assessment for predicting the opening of MACs. PATIENTS AND METHODS: The study included 204 consecutive patients who underwent MVD at our hospital between January 2014 and December 2018. We retrospectively collected clinical and neuroimaging data from electronic medical charts and discharge summaries. MACs were classified into four types according to neuroimaging data. Postoperative computed tomography (CT) was used to assess patients with and without CSF leakage into MACs. RESULTS: No CSF leakage was observed into types 1 and 2 MACs, but it was noted in 14 of 46 patients (30 %) with type 3 and 44 of 58 patients (76 %) with type 4 MACs. Opening of MACs during surgery could not be recognized in 33 (57 %). CSF rhinorrhea was noted in 1 of the 58 patients with CSF leakage into MACs and meningitis was not noted. CONCLUSION: Patients with types 3 and 4 MACs have a high risk of CSF leakage. Complete prevention of mild symptoms, such as ear obstruction, is challenging even if opened MACs are sealed, but serious complications, such as CSF rhinorrhea and meningitis, can be avoided. For cases in which preoperative CT reveals a high risk of opening of MACs, preventive closure should be performed.

Intracranial venous sinus stenosis: hemodynamic assessment with two-dimensional parametric parenchymal blood flow software on digital subtraction angiography.

OBJECTIVE: Intracranial venous sinus stenosis (IVSS) is the most common finding associated with idiopathic intracranial hypertension. A pressure gradient >8-10 mm Hg across the stenosis is considered hemodynamically significant, and typically responds to endovascular stent treatment. Here we assess the venous hemodynamics with two-dimensional (2D) parametric parenchymal blood flow software (Siemens-Healthineers, Forchheim, Germany) and its ability to predict significant IVSS. METHODS: Patients with IVSS treated at our institution between 2013 and 2018 were retrospectively reviewed. Measurements of contrast transit time on DSA were calculated with 2D parametric parenchymal blood flow software. Values were obtained proximally and distally to the stenotic region. Venous Stenosis Index (VSI) was defined as the ratio of the area under the curve (AUC) in the pre-stenotic vessel to the AUC in the post-stenotic vessel. VSI was compared between the stenotic and control groups at baseline, and before and after stent deployment in the stenotic group. The accuracy of VSI was assessed using the non-parametric receiver operating characteristic (ROC) curve. RESULTS: 11 patients with IVSS treated with venous stent deployment were included. Patients in the control group were similar in age, gender, and absence of major comorbidities. VSI in the IVSS group was significantly higher at baseline compared with the control group (1.42 vs 0.97, p=0.01). Area under the ROC was 0.82. After stent deployment, VSI decreased significantly compared with baseline (1.04 vs 1.42, p<0.01). CONCLUSION: 2D parametric parenchymal blood flow software is a useful tool which can accurately evaluate significant hemodynamic venous stenosis without intracranial catheterization, added radiation exposure, additional contrast injection, and periprocedural risks.

Pressure Mapping and Hemodynamic Assessment of Intracranial Dural Sinuses and Dural Arteriovenous Fistulas with 4D Flow MRI.

The feasibility of 4D flow MR imaging to visualize flow patterns and generate relative pressure maps in the dural venous sinus in healthy subjects (n = 60) and patients with dural arteriovenous fistulas (n = 7) was investigated. Dural venous drainage was classified based on torcular Herophili anatomy by using 4D flow MR imaging-derived angiograms and magnitude images. Subjects were scanned in a 3T clinical MR imaging system. 4D flow MR imaging enabled noninvasive characterization of dural sinus anatomy and mapping of relative pressure differences.

Assessment and Treatment of Peritumoral Cortical Veins in Parasagittal Meningiomas with Application of 3-Dimensional Imaging Fusion Model.

BACKGROUND: Operation of cortical veins is the keystone of parasagittal meningioma (PSM) resection. Little is known about pathologic changes of the veins and proper treatment. We built 3-dimensional (3D) image fusion models by neuronavigation to analyze the features of peritumoral cortical veins for PSMs and explore intraoperative treatment options. METHODS: We performed a prospective study of 42 consecutive surgically treated PSM patients who underwent preoperative evaluation of peritumoral cortical veins using a 3D venous-tumor fusion model established by a neuronavigation system. We categorized cortical veins into 3 types: single-end anastomosis (type a), tumor-to-end anastomosis (type b), and end-to-end anastomosis (type c). We present surgical strategies to operate these veins. RESULTS: Preoperative evaluation demonstrated 39 patients with peritumoral cortical veins. The 3D models show 100% of the veins (95 in total), which were confirmed intraoperation. The postoperative complication rates after vein injury were 60% (type a), 16.7% (type c), and 0% (type b). Ten patients (23.8%) had residual tumor because of venous protection (equal to Simpson grade III). After correlation analysis, type b and c cortical veins were positively correlated with tumor volume. CONCLUSIONS: The anastomoses of cortical veins may provide compensation for venous transaction. There may be a time-evolution relationship between different cortical veins (type a to c to b). Treatment of cortical veins should follow the following principles: single-end veins must be protected, tumor-to-end veins should be transacted directly, and end-to-end veins could be cut selectivity based on the degree of occlusion of the superior sagittal sinus. Detailed preoperative assessment of peritumoral cortical veins is critical for proper treatment.

Quantitative Evaluation of Noncontrast Computed Tomography of the Head for Assessment of Anemia.

BACKGROUND AND PURPOSE: Anemia is an underdiagnosed clinical entity with significant mortality and morbidity. We aimed to assess whether attenuation of dural venous sinuses correlates with hemoglobin/hematocrit and to determine if the degree of anemia can be predicted by quantitative analysis of unenhanced computed tomography (CT) of the head. MATERIALS AND METHODS: This is an institutional review board-approved retrospective study including 500 patients who underwent emergency department investigation for potential central nervous system etiology of their symptoms with unenhanced CT head at a tertiary care center. Computed tomographic attenuation values were obtained by 2 independent readers, whereas 2 separate investigators collected clinical data. Regression analyses were performed to evaluate the strength of correlation and the predictability of anemia and its severity on unenhanced CT. Receiver operating characteristic curve analyses were performed to evaluate sensitivity, specificity, as well as positive and negative predictive values. RESULTS: A total of 243 met the inclusion criteria, and attenuation values for all the dural venous sinuses were averaged and categorized according to hemoglobin values of less than 8, 8 to 10, 10 to 14, and greater than 14. Mean CT attenuation values for both readers were 36.30, 42.35, 47.99, and 53.25 Hounsfield units. Regression analysis revealed the highest positive correlation of hemoglobin/hematocrit with attenuation at the confluence of sinuses with R value of 0.63 and 0.60. The sensitivity, specificity, and negative predictive value of detecting hemoglobin of less than 10 at confluence of sinuses were 91.2%, 88.5%, and 98.6%, respectively. Interobserver agreement was found to be good (0.64) using the κ statistic. CONCLUSIONS: Our study substantiates direct positive correlation between CT attenuation of dural venous sinuses and hemoglobin/hematocrit, with strongest correlation at the confluence of sinuses with good sensitivity, specificity, and negative predictive value.

The assessment of anemia from attenuation values of cranial venous drainage on unenhanced computed tomography of the head.

OBJECTIVE: To determine if prediction of anemia is possible from quantitative analyses of unenhanced cranial computed tomography (CT) images. METHODS: A retrospective chart review revealed 101 patients who had hemoglobin and hematocrit levels obtained within 24 hours of an unenhanced cranial CT. Regions of interest were the place on the torcular Herophili (confluence of sinuses) and the left and right transverse sinuses. Attenuation values were correlated with hemoglobin and hematocrit to investigate any possible relationship. RESULTS: Hemoglobin levels were correlated with torcular and transverse sinus attenuation levels. For every 10 Hounsfield unit (HU) increase in torcular attenuation, hemoglobin levels increased by 16.3 g/L (P < .001). When subgroup analysis was performed, by sex, for every 10 HU increase in torcular attenuation, hemoglobin levels increased by 22.6 g/L (P < .001) in men and 8.96 g/L (P < .05) in women. CONCLUSION: The attenuation values for venous drainage on unenhanced cranial CT constitute a practical adjunct in the assessment of anemia. Given the number of individuals undergoing CT without blood work, this rapid assessment technique for anemia is a convenient means for narrowing possible diagnoses.

An anatomical assessment of the supracerebellar midline and paramedian approaches to the inferior colliculus for auditory midbrain implants using a neuronavigation model on cadaveric specimens.

The inferior colliculus (IC) is an alternative site for electrode placement in neural deafness due to its surgical accessibility and its well-known tonotopic stratification. In patients where tumor surgery has already occurred and the cerebellopontine angle contains scar tissue or tumor-remnants, midline and paramedian supracerebellar approaches are alternative routes. They are often avoided due to concerns regarding the venous drainage of the cerebellum, the electrode trajectory and the course of the electrode cable. We studied these surgical routes in five neuronavigated fixed cadaveric specimens. For paramedian and midline approaches, the transverse sinus was exposed 5.8mm on average. A mean of 1.6 cerebellar veins, with an average diameter of 2.0mm, draining to the tentorium were transected to reach the tentorial notch. Only 0.4 arterial branches were met. We conclude that the supracerebellar midline and paramedian approaches provide a good exposure of the IC and offer safe and viable alternative routes to the IC. Additionally, they provide a wider angle of action for optimal electrode placement.

Diagnostic value of multidetector-row CT angiography in the evaluation of thrombosis of the cerebral venous sinuses.

BACKGROUND AND PURPOSE: The diagnosis of cerebral venous and sinus thrombosis (CVST) as a rare but important cause of stroke is challenging. We aimed to investigate the diagnostic value of multidetector-row CT angiography (MDCTA) as a fast and cost-effective imaging tool in diagnosing CVST. MATERIALS AND METHODS: Nineteen patients who presented with clinical symptoms of a possible CVST were included. All patients had received both MDCTA and MR imaging with venous MR-angiography. Three blinded readers were asked to identify the cerebral sinuses and veins in MDCTA and to evaluate the presence of CVST in MDCTA. Consensus reading with interpretation of the MR imaging served to establish the definite diagnosis. RESULTS: The consensus reading revealed CVST in 10 of the 19 patients. With MDCTA, the venous sinuses could be identified in 99.2% and the cerebral veins in 87.6% of cases. The sensitivity and specificity of MDCTA for the diagnosis of CVST were 100%. CONCLUSION: Our study demonstrates that MDCTA provides excellent sensitivity and specificity for the diagnosis of CVST. Further studies are needed to evaluate the diagnostic potential of MDCTA in specific subsets of the general entity of CVST such as cortical venous thrombosis, thrombosis of the cavernous sinus, and thrombosis of the internal cerebral veins.

Phase-contrast magnetic resonance angiography for assessment of intracranial venous sinus lesions.

OBJECTIVE: To review the presentations of intracranial venous sinus lesions in phase-contrast (PC) magnetic resonance angiography (MRA) and discuss the diagnostic value of this imaging modality for these lesions. METHODS: This study involved 52 patients with intracranial venous sinus lesions, including 21 with dural venous sinus malformation, 7 dural arteriovenous fistula (6 caroticocaveneous fistula, CCF), 5 venous sinus thrombus and 19 meningioma invading the venous sinuses. All patients underwent PC and time-of-flight (TOF) MRA with a 1.5 Tesla MR scanner, with 28 of them undergoing subsequent digital subtraction angiography (DSA). RESULTS: PC MRA showed extensive hyperintense signals that identified the lesions, feeding arteries, deferent veins and venous sinuses in 21 cases of dural arteriovenous fistula, but the lesion signals appeared homogeneous. In these cases, PC and TOF MRA had equally good performance in displaying the feeding arteries with success in 20 of the 21 cases (95.2%), whereas the former resulted in a greater rate of deferent vein display [90.5% (19/21)] than the latter [76.2% (16/21), P<0.05]. The 6 CCF cases showed ipsilateral cavernous sinus expansion and upper ophthalmic vein dilations. In the 5 cases of venous sinus thrombis, 4 had transverse sinus thrombus and 1 superior sagittal sinus thrombus. All the cases presented signal disappearance in the sinuses in PC MRA and hyperintense signals in MRI, and some cases had also cerebral superficial hemorrhage and edema. The 19 cases of meningioma invading the venous sinus displayed sinus shift, stenosis and occlusion in PC MRA. CONCLUSION: PC MRA has great advantages in displaying the anatomical structure and lesions of the venous sinuses.

Assessment of mastoid air cell size versus sigmoid sinus variables with a tomography-assisted digital image processing program and morphometry.

We assessed the mastoid air cell size and variables of the sigmoid sinus in healthy ears and ears with chronic otitis media (COM). Thirty-eight patients with unilateral COM [15 with cholesteatoma (COM/+) and 23 without cholesteatoma (COM/-)], and 20 subjects with healthy ears, were included in the study. Assessment was performed using a quantitative digital image processing computed tomography (CT) program, and the volume of the mastoid bone was measured using the morphometric method of Cavalieri. In both COM/+ and COM/- patients the sigmoid to suprameatal spine distance and mastoid size were greater on the healthy side than on the diseased side ( p<0.05). The distance and area were significantly greater in the healthy control subjects than in either the healthy or the diseased ears of the patients with COM ( p<0.05). In the healthy ears of COM patients, there was significant correlation between the sigmoid to suprameatal spine distance and air cell size and mastoid volume ( p<0.05). In the diseased ears of COM patients, this correlation was absent ( p>0.05). The sigmoid sinus shape was of the half-moon type (62%), protrusive type (22%) and saucer type (16%). The digital image processing CT program allowed us to estimate the individual area of the air and soft tissue filled mastoid air cells. The mastoid size in both intact and disease ears of COM patients was smaller than in the healthy controls. The mastoid size may be determined genetically. However, environmental factors such as infection may also affect the mastoid size. Therefore, both genetic and environmental factors may be related to COM as far as the size of the mastoid air cells is concerned.

Two-dimensional thick-slice MR digital subtraction angiography for assessment of cerebrovascular occlusive diseases.

Although spatial resolution of current MR angiography is excellent, temporal resolution has remained unsatisfactory. We evaluated clinical applicability of 2D thick-slice, contrast-enhanced subtraction MR angiography (2D-MR digital subtraction angiography) with sub-second temporal resolution in cerebrovascular occlusive diseases. Twenty-five patients with cerebrovascular occlusive diseases (8 moyamoya diseases, 10 proximal internal carotid occlusions, and 2 sinus thromboses ) were studied with a 1.5-T MR unit. The MR digital subtraction angiography (MRDSA) was performed per 0.97 s continuously just after a bolus injection of 15 ml of gadolinium chelates up to 40 s in sagittal (covering hemisphere) or coronal planes. Subtraction images were generated at a workstation. We evaluated imaging quality and hemodynamic information of MRDSA in comparison with those of routine MR imaging, non-contrast MR angiography, and X-ray intra-arterial DSA. Major cerebral arteries, all of the venous sinuses, and most tributaries were clearly visualized with 2D MRDSA. Also, pure arterial phases were obtained in all cases. The MRDSA technique demonstrated prolonged circulation in sinus thromboses, distal patent lumen of proximal occlusion, and some collateral circulation. Such hemodynamic information was comparable to that of intra-arterial DSA. Two-dimensional thick-slice MRDSA with high temporal resolution has a unique ability to demonstrate cerebral hemodynamics equivalent to that of intra-arterial DSA and may play an important role for evaluation of cerebrovascular occlusive diseases.

The inferior petrosal sinus: assessment by transcranial Doppler ultrasound using the suboccipital approach.

Recently, intracranial veins and sinuses have been successfully insonated using the transtemporal and transoccipital approaches by transcranial Doppler ultrasound. The purpose of this study was to prove the capacity of the Doppler method to evaluate the inferior petrosal sinus via the suboccipital approach. Venous transcranial ultrasound was performed with a range-gated 2-MHz transducer in 80 healthy volunteers and patients without central nervous system disorders ranging in age from 15-84 years (mean +/- standard deviation [SD], 37.6 +/- 15.2 years). A venous signal with a flow directed toward the probe was considered to originate from the inferior petrosal sinus because of its proximity to the basilar artery. The inferior petrosal sinus was insonated in 96.3% of the cases at least on one side. It was found bilaterally in 48 (60%), on the right side in 74 (92.5%), and on the left side in 51 (63.8%) subjects, respectively. Mean blood flow velocity ranged from 8-53 cm/s (mean +/- SD, 19.6 +/- 8.7 cm/s). A significant age dependency of venous velocities was found. Weak but significant side-to-side differences were observed, reflecting the known right-sided predominance of venous outflow in humans. Using the suboccipital approach, the inferior petrosal sinus can be insonated in a high percentage of subjects without major difficulties and is defined by its vicinity to the basilar artery.

Transvaginal Doppler assessment of fetal intracranial venous flow.

OBJECTIVE: To investigate physiologic blood-flow-velocity waveform patterns of the fetal cerebral venous system during normal pregnancies by transvaginal Doppler studies and to evaluate cases with abnormal venous-flow patterns. METHODS: Internal cerebral veins and the three dural sinuses, those of the superior sagittal sinus, vein of Galen, and straight sinus, were examined in normal cephalic-presenting fetuses of 20-40 weeks' gestation. For analysis, the venous index was defined as maximum minus minimum velocity divided by maximum velocity. Different cases with intracranial abnormalities were evaluated with emphasis on abnormal venous blood-flow patterns. RESULTS: Internal cerebral veins had pulsatile patterns with a venous index of 0.22 in 47.6% of fetuses, whereas all fetuses had pulsations in the dural sinuses. The vein of Galen had a significantly lower venous index (0.31) than the superior sagittal sinus (0.39) and the straight sinus (0.36), indicating that the amplitude of the intracranial venous pulsation might increase as the flow runs from the periphery toward the proximal portion. Significant regression lines of venous index were obtained, indicating the stability of the pulsation during pregnancy. A flat pattern of superior sagittal sinus flow was found in three cases of hydrocephalus and one of craniosynostosis. CONCLUSION: We showed the normal patterns of fetal cerebral venous blood-flow velocity and the abnormal patterns which might be associated with increased intracranial pressure. Doppler assessment of the intracranial venous system enabled us to evaluate intracranial abnormalities accompanied by increased intracranial pressure that might have prognostic clinical importance.