Temporal Bone Thickness Research Articles

Cochlear implant positioning: development and validation of an automatic method using computed tomography image analysis.

An in-house designed semi-automatic algorithm was developed to analyse a 3D model of the skull. The feasibility of drilling the recess was determined by a gradient descent method to search for the thickest part of the temporal bone. Feasibility was determined by the residual bone thickness which was calculated after a simulated drilling of the recess at the thickest position. An initial validation of the algorithm was performed by measuring the accuracy of the algorithm on five 3D models with known thickest locations for the recess. The accuracy was determined by a part comparison between the known position and algorithm provided position. In four of the five validation models a standard deviation for accuracy below the predetermined cut-off value of 4.2 mm was achieved between the actual thickest position and the position determined by the algorithm. Furthermore, the residual thickness calculated by the algorithm showed a high agreement (max. 0.02 mm difference) with the actual thickness. With the developed algorithm, a semi-automatic method was created to analyse the temporal bone thickness within a specified region of interest on the skull. Thereby, providing indications for surgical feasibility, potential risks for anatomical structures and impact on procedure time of cochlear implantation. This method could be a valuable research tool to objectively assess feasibility of drilling a recess in patients with thin temporal bones preoperatively.

Variation of the human skull bone thickness with the age, gender, and body stature: an autopsy study of the Sri Lankan population

<strong><em>Introduction: </em></strong>Many characteristics of the skull bones used in identification are subjective. Since the human skull thickness (HST) can be used as a more objective criterion, it can be used in more accurate identification in forensic anthropology, and according to literature; no such studies were conducted in Sri Lanka. The aim of this study is to assess the thickness of individual skull bones and the association of the HST with age, gender, and body stature. <strong><em>Methods:</em></strong> A cross-sectional analytical study was carried out among 100 autopsies selected randomly at the National Hospital Kandy, and Teaching Hospital Peradeniya, Sri Lanka. Socio-demographic profile was collected using an interviewer-administered questionnaire; bone thickness was measured using a calibrated vernier caliper and body height was measured using a measuring tape.<em> </em>The association between the bone thickness with age and body stature was assessed using the Pearson linear correlation. The association of bone thickness with gender was calculated with Chi-square. <em></em> <strong><em>Results:</em></strong> The mean skull bone thicknesses obtained were temporal (4.7mm on both), parietal (6.1mm on right and 5.8mm on left), occipital (7.2mm on right and 6.4mm on left), and frontal (8.8mm), with the frontal bone being the thickest among both males and females. Skull bone thickness showed a significant difference with gender in occipital and frontal bones. Only the left temporal bone thickness showed a small positive correlation with age. HST showed no correlation with body stature.<em></em> <strong><em>Conclusion: </em></strong>This study shows that there are variations in HST with gender and no correlation with body stature.

Factors affecting transtemporal window quality in transcranial sonography.

ObjectiveTo assess the influencing factors of transtemporal window quality and identify patients suitable for transcranial sonography (TCS) examination in two‐dimensional imaging.MethodsIn this cross‐sectional study, TCS was performed in 161 consecutive patients through the temporal bone window (TBW) in the neurology or neurosurgery department. Each patient's sex, age, height, weight, and temporal bone thickness (TBT) were collected. After examination, the patients were divided into two groups: TBW success and TBW failure. The data were statistically compared between the two groups.ResultsAmong the studied population, the total TBW success rate was 80.1% (95% confidence interval [CI]: 74–86). The TBW success rate was 91.4% (95% CI: 85–98) in males and 70.9% (95% CI: 61–81) in females (p = .001). Sex (p = .001), age (p = .002), height (p = .047), and TBT (p < .001) showed significant differences between the TBW success and failure groups. In males, only TBT (p = .001) showed a significant difference; in females, age (p < .001) and TBT (p = .003) showed a significant difference. The area under the receiver operating characteristic curve (AUC) of sex, age, and TBT and their combination was 0.686, 0.659, 0.842, and 0.922 (p < .001), respectively. The AUC of the combination of parameters was significantly greater than that of age and sex alone (p = .007; p = .0002) but not greater than that of TBT (p = .090).ConclusionsThe TBW success rate varied with sex, age, height, and TBT. Males, younger patients, taller patients, and patients with a thinner temporal bone tended to be more suitable for the examination by TCS.

Quantitative Analysis of Temporal Bone Density and Thickness for Robotic Ear Surgery.

Background and Objective: Quantitative assessment of bone density and thickness in computed-tomography images offers great potential for preoperative planning procedures in robotic ear surgery.Methods: We retrospectively analyzed computed-tomography scans of subjects undergoing cochlear implantation (N = 39). In addition, scans of Thiel-fixated ex-vivo specimens were analyzed (N = 15). To estimate bone mineral density, quantitative computed-tomography data were obtained using a calibration phantom. The temporal bone thickness and cortical bone density were systematically assessed at retroauricular positions using an automated algorithm referenced by an anatomy-based coordinate system. Two indices are proposed to include information of bone density and thickness for the preoperative assessment of safe screw positions (Screw Implantation Safety Index, SISI) and mass distribution (Column Density Index, CODI). Linear mixed-effects models were used to assess the effects of age, gender, ear side and position on bone thickness, cortical bone density and the distribution of the indices.Results: Age, gender, and ear side only had negligible effects on temporal bone thickness and cortical bone density. The average radiodensity of cortical bone was 1,511 Hounsfield units, corresponding to a bone mineral density of 1,145 mg HA/cm3. Temporal bone thickness and cortical bone density depend on the distance from Henle's spine in posterior direction. Moreover, safe screw placement locations can be identified by computation of the SISI distribution. A local maximum in mass distribution was observed posteriorly to the supramastoid crest.Conclusions: We provide quantitative information about temporal bone density and thickness for applications in robotic and computer-assisted ear surgery. The proposed preoperative indices (SISI and CODI) can be applied to patient-specific cases to identify optimal regions with respect to bone density and thickness for safe screw placement and effective implant positioning.

Analysis of temporal bone thickness outside of the petrous temporal bone between superior semicircular canal dehiscence and normal patients

BackgroundSSCD is a rare inner ear disorder. This study aims to compare the thickness of the temporal bone beyond the petrous portion between healthy subjects and those with SSCD to determine whether the etiopathology of SSCD is localized to the petrous temporal bone or generalized to other parts of the temporal bone. MethodsA retrospective chart review of electronic medical records from September 2011 to February 2018 was conducted at a single-institution study at the University of California, Los Angeles. Participants were divided into two groups: Group 1 had a confirmed diagnosis of SSCD, while Group 2 had no known ear or temporal bone pathology. Participants’ high-resolution coronal and axial temporal bone computed tomography scans were analyzed. Regions within the temporal bone were measured and compared between the two groups. ResultsA total of 262 scans were included. Group 1 consisted of 103 scans, while Group 2 consisted of 159 scans. There was no statistically significant difference in the thickness of temporal bones between patients diagnosed with SSCD and patients without otologic disease. ConclusionThe results suggest that the etiology of SSCD is limited to the petrous portion of the temporal bone. SSCD may be unrelated to a larger process of global temporal bone degeneration. Additional clinical screening for regions outside the petrous temporal bone is not warranted unless SSCD patients present with symptoms characteristic of other temporal bone pathologies.

Association between Tomographic Characteristics of the Temporal Bone and Transtemporal Window Quality on Transcranial Color Doppler Ultrasound in Patients with Stroke or Transient Ischemic Attack

Transcranial color-coded Doppler (TCCD) is an ultrasonographic technique used to obtain and evaluate images of the cerebral parenchyma and to assess blood flow velocities of the intracranial vessels. One of the major limitations of TCCD is the failure to insonate through the transtemporal window, which occurs in about 5%–44% of patients. Temporal bone thickness has been strongly associated with transtemporal window failure (TWF). The aims of the study were to evaluate the association between TWF on TCCD and radiologic findings on computed tomography of the skull along with the demographic characteristics of patients with acute stroke or transient ischemic attack (TIA), and to propose a classification for transcranial window quality (TWQ) on B-mode scan of TCCD. A total of 187 consecutive patients with acute stroke or TIA were included. Among them, 21.9% had TWF and 34.8% had TWQ categorized as insufficient on B-mode scan of TCCD. On logistic regression, age (odds ratio [OR] = 1.07, 95% confidence interval [CI]: 1.03–1.12, p < 0.001), female sex (OR = 5.99, 95% CI: 2.09–17.16, p = 0.001), pneumatized temporal bone (OR = 7.90, 95% CI: 1.95–32.03, p = 0.004) and temporal bone thickness (OR = 3.04, 95% CI: 1.73–5.35, p < 0.001) were independent predictors of TWF, even after adjusting for confounders. These findings may help to select patients in whom echogenic contrast or even other imaging methods could be used to assess intracranial vessels.

Assessment of Temporal Bone Thickness for Implantation of a New Active Bone-Conduction Transducer.

To investigate the minimum bone thickness in adults and children in the area of the skull affected by implantation of a new bone conduction device in patients without known medical history that indicates anatomical malformations. Retrospective, non-interventional study on computer tomography (CT) scans on file at a university medical center. A digital model of the new bone conduction implant was virtually implanted in 3D reconstructions of temporal bones based on 197 CT scans, 132 from adults and 65 from children (evenly distributed in five different age groups). The bone thickness was measured in a total of 11 designated positions; five measurement points for the transducer (recess area), and six for the fixation screws, corresponding to three different positions for the fixation band holding the implant in place (screw area). The minimum bone thickness in the combined recess and screw area for adults was 5.55 ± 1.46 mm, with a 95% CI of 5.30 to 5.80 mm. For children, the thickness was 4.34 ± 2.29 mm (95% CI: 3.77-4.91 mm), increasing from 1.92 mm (0-4 yr) to 6.41 mm (12-14 yr). For all ages, the bone in the recess area was generally thicker compared with the screw area.With an implantation depth of 3 mm the transducer fitted in all of the adult temporal bones (100%) and 99.2% (131/132) of the adults had a bone thickness of at least 2.7 mm in all six measured screw positions. In all children from the age of 5 the transducer fitted at an implantation depth of 3 mm, and in all children from the age of 9, the fixation screws fitted at a depth of 2.7 mm. In all CT scans except for a 6-month-old child the new bone conduction device could be implanted in at least one of the fixation band positions analyzed. In adults and many children without known medical history that indicates anatomical malformations, the average minimum bone thickness was thicker than both the maximum transducer depth of 3 mm and the 2.7 mm bone involvement of the osseointegrating fixation screws. The results indicate implant fit of the new bone conduction implant in all adult patients. The risks of compromising the sigmoid sinus and the dura as considered with larger implants are thus significantly reduced. Preoperative planning with CT would still be recommended for children below 9 years old.

Image-guided surgical navigation for bone-conduction hearing device implant placement

IntroductionFor pediatric patients, bone-conduction hearing devices (BCHD) have demonstrated excellent outcomes. Unique to this population, BCHD implant surgeries can be technically challenging in children due to thinner, developing bone and syndromes with atypical anatomy. Image-guided surgical navigation (IGSN) clarifies underlying skull structure, potentially improving outcomes. IGSN is commonly used in otorhinolaryngologic surgeries, but current use in BCHD placement surgeries remains unprecedented. We report favorable results of IGSN in BCHD implantation for three children with complex otologic anatomy: two syndromic patients with variable temporal bone thickness, and one with prior mastoidectomies. The three patients each underwent a successful hearing implant surgery without significant intra- or post-surgical complications. All patients had good audiologic outcomes. Methods and materialsWe report using IGSN to assist in BAHA or BONEBRIDGE™ implant surgery for three medically complicated patients. For stereotactic imaging, the patients each received pre-operative high-resolution CT scans using the paranasal sinus fusion protocol without contrast.The first patient was a 6-year-old male with CHARGE-associated abnormal temporal bone anatomy, atretic left auditory nerve, and bilateral chronic tympanic membrane perforation and otorrhea resulting in bilateral mixed conductive and sensorineural hearing loss. The patient thus was unable to consistently tolerate hearing aids.The second patient was an 18-year-old male with Rosai-Dorfman disease, history of bilateral chronic mastoiditis and middle ear infections, bilateral mastoidectomies, and bilateral malleus and incus removal resulting in mixed conductive and sensorineural hearing loss.The third patient was an 11-year-old male with Treacher Collins Syndrome, bilateral microtia, and bilateral atresia of the external auditory canals resulting in bilateral conductive hearing loss. ResultsThe patients each underwent a successful hearing implant surgery without significant intra- or post-surgical complications. All patients had good audiologic outcomes. ConclusionIntraoperative IGSN can be a beneficial adjunct to BCHD implant placement surgeries for pediatric patients with abnormal temporal bone anatomy. IGSN can help identify the optimal surgical implantation sites, thereby reducing the risk for major morbidities associated with BCHD implantations. Furthermore, our findings expand application of IGSN use to placement of both BAHA and BONEBRIDGE™.

Factors associated with temporal window failure in transcranial Doppler sonography.

Temporal window failure (TWF) is found in 8-20% of subjects. There are still insufficient studies about the factors affecting TWF. We aimed to elucidate the underlying causes of TWF. We analyzed 376 patients who underwent both transcranial Doppler sonography and cerebral angiographic imaging. They were divided into two groups: with and without TWF. Demographics, cardiovascular factors, degree of stenosis from the proximal intracranial artery to the middle cerebral artery (MCA), MCA diameter, and skull features were examined. The subjects were 314 TWF-negative patients and 62 TWF-positive patients. The TWF-negative group was younger than that of the TWF-positive group (67.0 ± 12.1 vs. 75.2 ± 9.4, p < 0.001). The proportion of men in the TWF-negative group was higher than in the TWF-positive group (71% vs. 29%; p < 0.001). The TWF-negative group had a higher smoking rate than the TWF-positive group (34.4% vs. 12.9%; p = 0.001). In multivariate logistic regression analysis, age (odds ratio (OR), 1.05; p = 0.019), sex (OR, 4.64; p = 0.002), temporal bone thickness (OR, 6.03; p < 0.001), temporal bone density (OR, 0.996; p = 0.002), and soft tissue thickness (OR, 1.31; p = 0.004) significantly affected TWF. In addition to age, sex, temporal bone thickness, and temporal bone density which were previously reported as variables associated with TWF, we confirmed that soft tissue thickness of the temporal area is a new associated factor of TWF. Measuring soft tissue thickness of the temporal area for patients with suspected TWF could be useful in identifying measurement error due to technical problems.

Abstract TP203: Factors Associated With Temporal Window Failure in Transcranial Doppler Sonography

Background and purpose: Temporal window failure (TWF) is found in 8-20% of subjects. Although it has been reported that, it is more common for the elderly and females, there are not enough studies on this topic. This study aimed to identify new factors affecting TWF. Methods: This study analyzed 376 patients who underwent both transcranial Doppler sonography (TCD) and cerebral angiographic imaging among patients visited the neurology department of Chonbuk National University Hospital from January to December 2018. They were divided into two groups depending on the presence of TWF. Afterward, demographics and cardiovascular factors, degree of stenosis from proximal intracranial artery (ICA) to the middle cerebral artery (MCA), and MCA diameter and skull features were examined. Results: The mean age of the patients was 68.4±12.1 years old and 241 of them (64.1%) were male. The study subjects were composed of 314 TWF negative patients (83.5%) and 62 TWF positive patients (16.5%). The stenosis from the proximal ICA to the 2/3 segment of the MCA proximal was not different between the two groups. Factors affecting TWF were analyzed using multivariate logistic regression analysis and the results showed that age (odds ratio [OR], 1.05; p =0.019), female (OR, 4.64; p =0.002), temporal bone thickness (OR, 6.03; p &lt;0.001), temporal bone density (OR, 0.996; p =0.002), and soft tissue thickness (OR, 1.31; p =0.004) significantly affected TWF. Conclusions: We confirmed that the soft tissue thickness of the temporal area was a new associated factor of TWF in addition to the previously reported age, sex, temporal bone thickness, and temporal bone density. The results implied that measuring the soft tissue thickness of the temporal area for patients with suspected TWF would be useful to clinically identify the measurement error due to a technical problem.

Increased frequency of temporal acoustic window failure in rheumatoid arthritis: a manifestation of altered bone metabolism?

Assessment of intracranial vessels includes transcranial Doppler (TCD). TCD performance requires intact temporal acoustic windows (TAW). Failure of TAW (TAWF) is present in 8-20% of people. There have been no reports on TAWF in rheumatoid arthritis (RA). Altogether, 62 female RA patients were included. Among them, 20 were MTX-treated and biologic-free, 20 received infliximab, and 22 tocilizumab. The controls included 60 non-RA women. TAWF, temporal bone thickness, and texture were determined by ultrasound and CT. BMD and T-scores of multiple bones were determined by DEXA. Several bone biomarkers were assessed by ELISA. In RA, 54.8% of the patients had TAWF on at least one side. Neither TAW could be identified in 34% of RA subjects. In contrast, only 20.0% of control subjects had TAWF on either or both sides (p < 0.001). In RA vs controls, 53.0 vs 2.9% of subjects exerted the trilayer, "sandwich-like" structure of TAW (p < 0.001). Finally, in RA vs controls, the mean temporal bone thickness values of the right TAW were 3.58 ± 1.43 vs 2.92 ± 1.22mm (p = NS), while those of the left TAW were 4.16 ± 1.56 vs 2.90 ± 1.16mm (p = 0.001). There was close association between TAWF, bone thickness, and texture (p < 0.05). These TAW parameters all correlated with age; however, TAW failure and texture also correlated with serum osteoprotegerin. TAW bone thickness inversely correlated with hip BMD (p < 0.05). TAWF, thicker, and heterogeneous temporal bones were associated with RA. These features have been associated with bone loss and OPG production. Bone loss seen in RA may result in OPG release and stimulation of bone formation around TAW.

Pediatric Calvarial Bone Thickness in Patients With and Without Aural Atresia.

To compare temporal bone thickness along a three-dimensional arc of potential osseointegrated implant sites for bone-anchored hearing aids in children with and without aural atresia using computed tomographic imaging (CT). Retrospective case review. Tertiary children's hospital. Children with or without aural atresia aged less than 11 years who had a temporal bone CT. Calvarial bone volume on CT was rendered in three-dimensional and thickness was reconstructed and measured at up to 12 defined sites along an arc of recommended implant sites. Determining whether a majority of observed potential implant sites have 2, 3, or 4 mm of bone thickness while controlling for age differences and atresia status. A total of 40 atretic (from 34 patients) and 34 control (from 34 patients) temporal bones were compared using CT. Likelihood ratio tests indicated that diagnosis did not have a statistically significant effect on whether patients reached thresholds of 2, 3, or 4 mm at most observed sites (p = 0.781, 0.773, and 0.529, respectively) when adjusting for age. For all children measured, 93% had >50% of measured points greater than or equal to 2 mm thick. Most children had greater than 2 mm of temporal bone thickness at >50% of the sites measured regardless of age or atresia diagnosis. The likelihood of reaching 4 mm of thickness at most sites improves with age. In unilateral patients, there was not a significant difference in thickness between affected and unaffected sides. There was also no significant difference in thickness when comparing patients with atresia to those without.

Clinical Importance of Temporal Bone Features for the Efficacy of Contrast-Enhanced Sonothrombolysis: a Retrospective Analysis of the NOR-SASS Trial.

Contrast-enhanced sonothrombolysis (CEST) seems to be a safe and promising treatment in acute ischemic stroke. It remains unknown if temporal bone features may influence the efficacy of CEST. We investigated the association between different temporal bone features on admission computed tomography (CT) scan and the outcome in acute ischemic stroke patients included in the randomized Norwegian Sonothrombolysis in Acute Stroke Study (NOR-SASS). Patients diagnosed as stroke mimics and those with infratentorial stroke or with incorrect insonation were excluded. We retrospectively assessed temporal bone heterogeneity (presence of diploë), diploë ratio, thickness, and density on admission CT scans. National institute of Health Stroke Scale (NIHSS) at 24h and modified Rankin Scale (mRS) at 3months were correlated with CT findings both in CEST and sham CEST patients. A total of 99 patients were included of which 52 were assigned to CEST and 47 to sham CEST. Approximately 20% patients had a heterogeneous temporal bone in both the CEST and sham CEST group. All temporal bone CT features studied were associated with female sex. In the CEST group, temporal bone heterogeneity (p=0.006) and higher temporal bone diploë ratio (p=0.002) were associated with higher NIHSS at 24h. There was no association between temporal bone features and mRS at 3months. Approximately 20% of acute ischemic stroke patients have heterogeneous temporal bone and may be resistant to standard 2-MHz transcranial Doppler ultrasound treatment. Sonothrombolysis resistance may easily be predicted by admission CT for better selection.

A Retrospective Review of Temporal Bone Imaging With Respect to Bone-Anchored Hearing Aid Placement.

Current bone-anchored hearing aid (BAHA) guidelines recommend placement of the titanium implant 5 to 7 cm posterior to the ear canal. Previous studies show that bone conducted hearing is maximized the closer the transducer is to the cochlea. We aim to investigate the position of the sigmoid sinus with respect to BAHA implants to determine whether they may be safely placed closer to the ear canal in patients with chronic ear disease, enhancing the amplification available to the patient. We performed a retrospective review of high-resolution temporal bone computed tomographies (CTs), comparing multiple measurements between ears with chronic ear disease and normal controls. Images were obtained at a single academic medical center. Eighty patients (160 ears) with temporal bone CTs performed between 2006 and 2009 were measured. Patients with chronic ear disease were identified by international statistical classification of diseases and related health problems, revision 9 code and confirmation by review of the imaging. Measurements were made on axial CT slices from a point 1 cm posterior to the sigmoid sinus to the posterior margin of the external canal. The squamous temporal bone thickness was also measured at this point. Forty-seven patients (55 ears) had chronic ear disease. Distance from the posterior canal was significantly different between normal and diseased ears (36.3 mm versus 33.5 mm, p < 0.001). Squamous temporal bone thickness varied widely, and was similar between groups (6.9 mm versus 6.8 mm, p = 0.76). According to our data, titanium implants for bone-anchored hearing aids may be safely placed closer to the external canal than the current recommendations. This could allow for better transduction as well as sound localization in BAHA patients.

A Review of Temporal Bone CT Imaging With Respect to Pediatric Bone-anchored Hearing Aid Placement.

Bone-anchored hearing aid has been shown to be effective in hearing rehabilitation for conductive loss or single-sided deafness. Current FDA guidelines allow implantation in patients over 5 years old. This guideline is at least partially due to concern for thickness of bone stock at the implant site. We aim to investigate whether temporal bone thickness should be a deterrent to implantation in those younger than five. A retrospective review of high-resolution temporal bone computed tomographies (CTs) comparing measurements between ears with chronic disease and controls. Single institution tertiary care center. One hundred patients between 1 and 5.99 years had temporal bone CTs performed between 2000 and 2009. Patients with chronic ear disease were identified by ICD-9 code, as well as confirmation by review of the imaging. None. Temporal bone thickness was measured on axial CT slices at a point 1 cm posterior to the sigmoid sinus, at the superior margin of the bony canal. Average thickness was greater than 3 mm in all age groups. No significant difference was found between age groups, or between normal ears and ears with chronic disease (3.5 mm versus 3.3 mm, p = 0.21) when compared individually. This data shows pediatric temporal bone thickness is frequently greater than the recommended 3 mm, even in patients as young as one. Anatomically, concerns regarding temporal bone thickness in patients younger than five could be reliably addressed with imaging typically obtained in workup of hearing loss.

Pediatric Semicircular Canal Dehiscence: Radiographic and Histologic Prevalence, With Clinical Correlation.

To determine the prevalence of radiographic and histologic superior semicircular canal dehiscence (SSCD) and posterior semicircular canal dehiscence (PSCD) and associated changes in temporal bone thickness in children aged 0 to 7 years. Retrospective chart review and histopathologic review of cadaveric bone specimens. Two tertiary referral centers. Children younger than 7 years who underwent high-resolution computed tomography scan including the temporal bones between 1998 and 2013 and temporal bones harvested from children younger than 7 years. Two hundred twenty-eight computed tomography studies and 58 temporal bone specimens were reviewed. Available patient demographics were tabulated. Prevalence of SSCD and PSCD and bone thickness over semicircular canals, with comparison across age groups. Clinical data were extracted for patients with radiographic dehiscence. Prevalence by ear of SSCD was 11.9%, 4.9%, 2.8%, and 0% and of PSCD was 16.7%, 2.4%, 1.4%, and 0% in children aged less than 6 months, 6 to 11 months, 12 to 35 months, and 3 to 7 years, respectively. SSCD was statistically more common before 1 year of age and PSCD before 6 months of age. Bone thickness overlying both the SSC and the PSC increased with age. Radiographic PSC bone was significantly thicker than SSC bone in patients older than 12 months. No dehiscences were found in the histologic specimens. Radiographic dehiscence of the canals is common in the first 6 months of life, with thin bone seen histologically. Prevalence decreases with increasing age as the bone overlying the canals increases in thickness.

Temporal bone thickness and texture are major determinants of the high rate of insonation failures of transcranial Doppler in Amerindians (the Atahualpa Project).

To assess the role of temporal bone characteristics in transcranial Doppler (TCD) insonation failures in Amerindians living in rural Ecuador. We evaluated thickness and texture of temporal bones in community-dwelling Amerindians ≥65 years old undergoing TCD. Using receiver operator characteristics curve analysis and generalized estimating equations, we investigated factors associated with insonation failures. Of 65 participants (mean age 74.7 ± 6.7 years, 60% women), 32 (49%) had uni- or bilateral insonation failure through temporal windows. Considering temporal bones independently, 57 of 130 (44%) had poor insonation. Mean thickness was higher (4.7 ± 1.2 versus 2.7 ± 0.9, p < 0.0001), and texture more often heterogeneous (93% versus 22%, p < 0.0001) in bones with poor acoustic windows. Thickness, better predicting poor insonation, was ≥3.6 mm if used alone, and ≥2.7 mm if used together with heterogeneous texture. For every millimeter of increase in thickness, subjects were 2.9 times more likely to have insonation failures. Per se, heterogeneous texture increased by 3.2 times the odds for poor insonation. In all models, being woman increased the odds for poor insonation by six to nine times. Temporal bone thickness and texture are independent predictors of TCD insonation failure in Amerindians.

Exploratory analysis of estimated acoustic peak rarefaction pressure, recanalization, and outcome in the transcranial ultrasound in clinical sonothrombolysis trial

Acoustic peak rarefaction pressure (APRP) is the main factor that influences ultrasound-enhanced thrombolysis. We sought to determine whether recanalization rate and functional outcomes in the Transcranial Ultrasound in Clinical SONothrombolysis (TUCSON) trial could be predicted by estimated in vivo APRP. We developed an acoustic attenuation model to estimate the in vivo APRP at the arterial occlusion site in each subject of the TUCSON trial with CT scans eligible for measurements. Variables included temporal bone thickness, depth of arterial occlusion site, and average attenuation of skin and brain tissues. Recanalization was defined as partial or complete using the Thrombolysis in Brain Infarction flow grades. Functional independence was assessed at 3 months using the modified Rankin Scale score (mRS, 0-1). APRP was calculated in 20 acute ischemic stroke patients treated with sonothrombolysis (mean age, 64 ± 15 years, 65% men; median NIHSS score, 13; IQR, 6-17). The mean APRP was 30.2 ± 15.5 kPa (range, 8-68 kPa). Patients with persisting occlusion had nonsignificantly lower APRP than patients with partial or complete recanalization (25.2 ± 8.0 versus 32.3 ± 17.7 kPa; p = 0.228). Patients who were functionally independent at 3 months had nonsignificantly higher APRP than patients with worse outcome (35.1 ± 19.5 versus 25.9 ± 11.2 kPa; p = 0.217). Our exploratory analysis suggests a potentially important role of successful energy delivery to augment thrombolysis with 2-MHz ultrasound in acute ischemic stroke patients.

Rate of Occurrence, Gross Appearance, and Age Relation of Hyperostosis Frontalis Interna in Females

The aim of our study was to determine rate of occurrence and appearance of hyperostosis frontalis interna (HFI) in females and correlation of this phenomenon with ageing. The sample included 248 deceased females: 45 of them with different types of HFI, and 203 without HFI, average age 68.3 +/- 15.4 years (range, 19-93), and 58.2 +/- 20.2 years (range, 10-101), respectively. According to our results, the rate of HFI was 18.14%. The older the woman was, the higher the possibility of HFI occurring (Pearson correlation 0.211, N=248, P=0.001), but the type of HFI did not correlate with age (Pearson correlation 0.229, N=45, P=0.131). Frontal and temporal bone were significantly thicker in women with than in women without HFI (t= -10.490, DF=246, P=0.000, and t= -5.658, DF=246, P=0.000, respectively). These bones became thicker with ageing (Pearson correlation 0.178, N=248, P=0.005, and 0.303, N=248, P=0.000, respectively). The best predictors of HFI occurrence were respectively, frontal bone thickness, temporal bone thickness, and age(Wald. coeff.=35.487, P=0.000; Wald. coeff.=3.288, P=0.070, and Wald.coeff. =2.727, P =0.099). Diagnosis of HFI depends not only on frontal bone thickness, but also on waviness of internal plate of the frontal bone, as well as-the involvement of the inner bone surface.

Can a Commercial Diagnostic Ultrasound Device Accelerate Thrombolysis?

Recently, 3 clinical trials revealed encouraging results in recanalization and clinical outcome in acute stroke patients when 2-MHz transcranial Doppler monitoring was applied. This study investigated whether a 1.8-MHz commercial diagnostic ultrasound device has the potential to facilitate thrombolysis using an in vitro stroke model. Duplex-Doppler, continuous wave-Doppler, and pulsed wave (PW)-Doppler were compared on their impact on recombinant tissue plasminogen activator (rtPA)-mediated thrombolysis. Blood clots were transtemporally sonicated in a human stroke model. Furthermore, ultrasound attenuation of 5 temporal bones of different thickness was determined. In comparison, only PW-Doppler accelerated rtPA-mediated thrombolysis significantly. Without temporal bone, PW-Doppler plus rtPA showed a significant enhancement in relative clot weight loss of 23.7% when compared with clots treated with rtPA only (33.9+/-5.5% versus 27.4+/-5.2%; P<0.0005). Ultrasound attenuation measurements revealed decreases of the output intensity of 86.8% (8.8 dB) up to 99.2% (21.2 dB), depending on temporal bone thickness (1.91 to 5.01 mm). Without temporal bone, PW-Doppler significantly enhanced thrombolysis. However, because of a high attenuation of ultrasound by temporal bone, no thrombolytic effect was observed in our in vitro model, although Doppler imaging through the same temporal bone was still possible.