Occipital Angle Research Articles

Predictive Value of Sonographic Parameters on the Effects of Cranial Molding Helmet Therapy in Infants with Positional Plagiocephaly.

Positional plagiocephaly is a deformational cranial flattening frequently treated in pediatric neurosurgical practice. Positional maneuvers and orthotic helmet therapy are preferred therapeutic options for moderate-to-severe forms. Treatment response seems to be age-dependent. Nevertheless, predictive data are vague, and cost-efficiency might be a limiting factor for treatment. The purpose of this study was to investigate the early predictive value of sonographic parameters on the efficacy of orthotic helmet therapy through the assessment of changes in skull shape and correlation of the parameters with caliper cephalometry values and with age. A consecutive cohort of 49 patients < 10 months of age, undergoing orthotic helmet therapy for positional plagiocephaly, was recruited prospectively. The authors routinely assessed the patency of the lambdoid sutures by ultrasound and the following additional skull parameters were measured: suture width, adjacent full bone thickness, adjacent cortical bone thickness and occipital angle. Caliper cephalometric values, as well as demographic and clinical data were collected. Retrospective data analysis showed an inverse relation between both cortical and full skull bone thickness and early treatment efficacy, defined by a reduction in the occipital angle. The improvement of sonographic parameters correlated with the development of cranial caliper cephalometry values. In conclusion, the sonographic assessment of skull bone thickness is a safe and cost-effective tool to predict the early efficacy of orthotic helmet therapy in positional plagiocephaly and might, therefore, help the clinician to foresee the potential evolution of the deformity.

Do Birth Outcomes Predicted by Occipital Position Inform Definitions of Occiput Posterior and Occiput Transverse?

Fetal head position significantly influences birth outcomes, with higher rates of complications observed when the fetal head is in the Occiput Posterior (OP) position compared to Occiput Transverse (OT) or Occiput Anterior (OA) positions. There is no consensus in the current literature on the precise rotational point at which the fetal occiput shifts from posterior to transverse, reducing clarity in both scientific and clinical communication. Different studies employ varying definitions of these positions, which affects management decisions. This study aims to determine if a definable threshold exists between the directly posterior and directly transverse positions that correlates with different birth outcomes, thereby proposing a consistent and clinically useful definition for OP versus OT. We analyzed ultrasound data from 570 patients at full dilatation from five previous studies, correlating the angle of the fetal occiput (noted on a clock-face) with birth outcomes. Adverse outcomes were defined as cesarean delivery, instrumental vaginal delivery, significant postpartum hemorrhage (500 ml or more), obstetric anal sphincter injury, five-minute Apgar scores <7, arterial cord pH <7, base excess less than -12, or neonatal intensive care unit admission. The analysis was conducted using SAS version 9.4. The study found a continuous relationship between the fetal occipital angle and adverse birth outcomes without a distinct threshold separating OP from OT positions. No clear inflection point was demonstrated in pregnancy outcomes between OT and OP. The relationship between the angle of occiput position and pregnancy outcomes was continuous: the closer the fetal head was to directly OP, the higher the likelihood of adverse outcomes. Given the lack of a clear cut-off and to improve consistency in future research, we recommend dividing the occiput position into four quadrants of 90 degrees each. This classification could standardize reporting and potentially improve clinical decision-making regarding fetal position during labor.

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

No previous study has evaluated the transitions of intrapartum transperineal ultrasound parameters during labor progression in cephalic malposition. 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. 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. 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). 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.

ПРОЦЕС РІЗАННЯ ҐРУНТУ НОЖАМИ РОТОРА КОМБІНОВАНОГО ЛЕМІШНО-ПОЛИЦЕВОГО ПЛУГА

Обробіток ґрунту є найбільш енергоємним та затратним процесом, тому створення комбінованих машин, виконуючих за один робочий прохід декілька операцій є актуальним питанням на сьогодні, вирішення якого нерозривно пов’язане з об’єднанням сільськогосподарських операцій в один технологічний процес, що приносить економічні, організаційні та агробіологічні переваги. Виходячи з особливостей підготовки ґрунту під посів чи посадку сільськогосподарських культур як об’єкту, та необхідності подальшого наукового проектування комбінованого технологічного процесу обробітку ґрунту внесення добрив, активного кришення пласта та заробки кореневих, рослинних решток та добрив як предмету, метою наукових досліджень є аналіз взаємодії ротора з пластом, визначення та оптимізація основних параметрів ножів, радіуса, частоти обертання з огляду на забезпечення класичного різання ґрунту і перемішування з добривами. В Подільському державному агротехнічному університеті розроблено конструкцію комбінованого плуга, технологічний процес роботи якого об’єднує операції глибокої оранки, активне подрібнення пласта і заробки кореневих і пожнивних решток, а також внесення мінеральних добрив. В результаті досліджень обґрунтовано кути установки ножа по відношенню радіуса ротора α, кута загострення γ, кута різання ψр, затилочного кута ζ, кута конусності ротора β, кута зміщення лопастей (променів) кріплення, величини трансформації кута загострення. Проведено аналіз сил, діючих на частинку ґрунту, і визначено необхідну частоту обертання, при якій ґрунт проходить по поверхні ножа без завантаження, при цьому забезпечується ефект його розвантаження.

Sonographic Analysis of Changes in Skull Shape After Cranial Molding Helmet Therapy in Infants With Deformational Plagiocephaly.

-The purpose of this study was to investigate the changes in skull shape on sonography after cranial molding helmet therapy in infants with deformational plagiocephaly. -Twenty-six infants who were treated with cranial molding helmet therapy were recruited. Caliper and sonographic measurements were performed. The lateral length of the affected and unaffected sides of the skull and cranial vault asymmetry index were measured with calipers. The occipital angle, defined as the angle between lines projected along the lambdoid sutures of the skull, was calculated by sonography. The occipital angle difference and occipital angle ratio were also measured. All caliper and sonographic measurements were performed in each infant twice before and twice after treatment. -The study group included 12 male and 14 female infants with a mean age ± SD of 6.2 ± 3.5 months. The mean treatment duration was 6.0 ± 2.5 months. The difference in lateral length before and after helmet therapy was significantly greater on the affected skull than the unaffected skull (16.7 ± 12.7 versus 9.0 ± 13.4 mm; P < .01). The difference in the occipital angle before and after helmet therapy was significantly greater on the affected skull than the unaffected skull (-5.7° ± 7.3° versus 4.2° ± 7.9°; P < .01). The cranial vault asymmetry index and occipital angle ratio were significantly reduced after helmet therapy (cranial vault asymmetry index, 9.3% ± 2.3% versus 3.5% ± 3.0%; occipital angle ratio, 1.07 ± 0.05 versus 1.01 ± 0.01; P < .05). -These results suggest that occipital angle measurements using sonography, combined with cephalometry, could provide a better understanding of the therapeutic effects of cranial molding helmet therapy in infants with deformational plagiocephaly.

Variation of the slope of the tentorium during childhood.

Neural structures in the posterior fossa grow at different rates during development. While there are computationally intensive approaches to analyze growth of the cerebellum and brainstem, there is a paucity of information about summary measures of normal posterior fossa development suitable for real-time clinical use. The present study investigates changes in the trajectory of the tentorium as measured by the occipital and tentorial angles at different stages of development. A retrospective study was conducted drawing from a Boston Children's Hospital database of over 1500 magnetic resonance imaging (MRI) studies. The imaging study population included fetuses older than 20 gestational weeks and children between the ages of 0 and 10years. Two parameters were measured for all subjects: (1) the tentorial angle (the angle between the tentorium and a line from the internal occipital protuberance to the tuberculum sellae) and (2) the occipital angle (the angle between the tentorium and a line from the internal occipital protuberance to the opisthion). Descriptive statistics were used to analyze the study cohort. We reviewed 1510 brain MRI studies, and 367 studies met the inclusion criteria (125 fetal and 242 postnatal studies). During fetal development, the inclination of the tentorium showed an ascending course, while it plateaus after birth. During the second and third trimesters, the tentorial and occipital angles steadily increase reflecting the dynamic growth of the posterior fossa structures. Postnatally, the tentorial angle decreases and the tentorium slopes downward and plateaus, possibly due to stabilization of posterior fossa development and ongoing growth of the cerebrum. Together, these findings suggest that the tentorial angle can serve as an imaging biomarker of posterior fossa development during the second half of fetal life.

Spine Surgeon's Kinematics during Discectomy, Part II: Operating Table Height and Visualization Methods, Including Microscope

Introduction Surgeon spine angle during surgery was studied ergonomically and the kinematics of the surgeon's spine was related with musculoskeletal fatigue and pain. Spine angles varied depending on operation table height and visualization method, and in a previous paper we showed that the use of a loupe and a table height at the midpoint between the umbilicus and the sternum are optimal for reducing musculoskeletal loading. However, no studies have previously included a microscope as a possible visualization method. The objective of this study is to assess differences in surgeon spine angles depending on operating table height and visualization method, including microscope. Materials and Methods We enrolled 18 experienced spine surgeons for this study, who each performed a discectomy using a spine surgery simulator. Three different methods were used to visualize the surgical field (naked eye, loupe, microscope) and three different operating table heights (anterior superior iliac spine, umbilicus, the midpoint between the umbilicus and the sternum) were studied. Whole spine angles were compared for three different views during the discectomy simulation: midline, ipsilateral, and contralateral. A 16-camera optoelectronic motion analysis system was used, and 16 markers were placed from the head to the pelvis. Lumbar lordosis, thoracic kyphosis, cervical lordosis, and occipital angle were compared between the different operating table heights and visualization methods as well as a natural standing position. Results Whole spine angles differed significantly depending on visualization method. All parameters were closer to natural standing values when discectomy was performed with a microscope, and there were no differences between the naked eye and the loupe. Whole spine angles were also found to differ from the natural standing position depending on operating table height, and became closer to natural standing position values as the operating table height increased, independent of the visualization method. When using a microscope, lumbar lordosis, thoracic kyphosis, and cervical lordosis showed no differences according to table heights above the umbilicus. Conclusion This study suggests that the use of a microscope and a table height above the umbilicus are optimal for reducing surgeon musculoskeletal fatigue. Disclosure of Interest J. Y. Park: Conflict with Technology Innovation Program (10040097) funded by the Ministry of Trade, Industry and Energy, Republic of Korea (MOTIE, Korea) S. U. Kuh: None declared Y. E. Cho: Conflict with Technology Innovation Program (10040097) funded by the Ministry of Trade, Industry and Energy, Republic of Korea (MOTIE, Korea) References Wunderlich M, Jacob R, Stelzig Y, Rüther T, Leyk D. [Analysis of spinal stress during surgery in otolaryngology]. HNO 2010;58(8):791–798 Park JY, Kim KH, Kuh SU, Chin DK, Kim KS, Cho YE. Spine surgeon's kinematics during discectomy according to operating table height and the methods to visualize the surgical field. Eur Spine J 2012;21(12):2704–2712 van Det MJ, Meijerink WJ, Hoff C, Totté ER, Pierie JP. Optimal ergonomics for laparoscopic surgery in minimally invasive surgery suites: a review and guidelines. Surg Endosc 2009;23(6):1279–1285 Kant IJ, de Jong LC, van Rijssen-Moll M, Borm PJ. A survey of static and dynamic work postures of operating room staff. Int Arch Occup Environ Health 1992;63(6):423–428 Shirzadi A, Mukherjee D, Drazin DG, et al. Use of the video telescope operating monitor (VITOM) as an alternative to the operating microscope in spine surgery. Spine 2012;37(24):E1517-E1523 Postacchini F, Postacchini R. Operative management of lumbar disc herniation : the evolution of knowledge and surgical techniques in the last century. Acta Neurochir Suppl (Wien) 2011;108:17–21 Kranenburg G, Gossot. Ergonomic problems encountered during video-assisted thoracic surgery. Minim Invasive Ther Allied Technol 2004;13(3):147–155 Lee G, Lee T, Dexter D, et al. Ergonomic risk associated with assisting in minimally invasive surgery. Surg Endosc 2009;23(1):182–188 Mirbod SM, Yoshida H, Miyamoto K, Miyashita K, Inaba R, Iwata H. Subjective complaints in orthopedists and general surgeons. Int Arch Occup Environ Health 1995;67(3):179–186 Cenic A, Kachur E. Lumbar discectomy: a national survey of neurosurgeons and literature review. Can J Neurol Sci 2009;36(2):196–200 Branson BG, Bray KK, Gadbury-Amyot C, et al. Effect of magnification lenses on student operator posture. J Dent Educ 2004;68(3):384–389 Mamoun JS. A rationale for the use of high-powered magnification or microscopes in general dentistry. 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A New Ultrasound Method for Assessment of Head Shape Change in Infants With Plagiocephaly

ObjectiveTo compare a new ultrasound measurement method with calliper cephalometry in infants with deformational plagiocephaly (DP) and to assess the differences of two methods according to the severity of DP.MethodsFifty-two infants with DP were divided into two groups according to the degree of cranial vault asymmetry (CVA); group 1 included 42 infants with CVA over 10 mm, and group 2 included 10 infants with CVA under 10 mm. Cranial vault asymmetry index (CVAI) and occipital angle ratio (OAR) were measured by using calliper and ultrasound measurements, respectively. The occipital angle was defined as the angle between the lines projected along the lambdoid sutures of the skull.ResultsThe occipital angles of the affected sides were significantly greater than those of unaffected sides in both groups. The CVAI and OAR were significantly greater in group 1 than in group 2 (CVAI, 9.3%±2.3% vs. 4.6%±1.5%; OAR, 1.05±0.4 vs. 1.01±0.0; p<0.05). The OAR was positively correlated with the CVAI in all infants (r=0.789) and in group 1 (r=0.784; p<0.05).ConclusionOur study revealed that OAR using the new ultrasound measurement was positively correlated with the CVAI in infants with DP. Therefore, the occipital angle measurement using ultrasound combined with cephalometry could provide better understanding about the characteristics of the overall cranial bone and lambdoid suture complex in infants with DP.

Spine surgeon’s kinematics during discectomy, part II: Operating table height and visualization methods, including microscope

Surgeon spine angle during surgery was studied ergonomically and the kinematics of the surgeon's spine was related with musculoskeletal fatigue and pain. Spine angles varied depending on operation table height and visualization method, and in a previous paper we showed that the use of a loupe and a table height at the midpoint between the umbilicus and the sternum are optimal for reducing musculoskeletal loading. However, no studies have previously included a microscope as a possible visualization method. The objective of this study is to assess differences in surgeon spine angles depending on operating table height and visualization method, including microscope. We enrolled 18 experienced spine surgeons for this study, who each performed a discectomy using a spine surgery simulator. Three different methods were used to visualize the surgical field (naked eye, loupe, microscope) and three different operating table heights (anterior superior iliac spine, umbilicus, the midpoint between the umbilicus and the sternum) were studied. Whole spine angles were compared for three different views during the discectomy simulation: midline, ipsilateral, and contralateral. A 16-camera optoelectronic motion analysis system was used, and 16 markers were placed from the head to the pelvis. Lumbar lordosis, thoracic kyphosis, cervical lordosis, and occipital angle were compared between the different operating table heights and visualization methods as well as a natural standing position. Whole spine angles differed significantly depending on visualization method. All parameters were closer to natural standing values when discectomy was performed with a microscope, and there were no differences between the naked eye and the loupe. Whole spine angles were also found to differ from the natural standing position depending on operating table height, and became closer to natural standing position values as the operating table height increased, independent of the visualization method. When using a microscope, lumbar lordosis, thoracic kyphosis, and cervical lordosis showed no differences according to table heights above the umbilicus. This study suggests that the use of a microscope and a table height above the umbilicus are optimal for reducing surgeon musculoskeletal fatigue.

Spine surgeon’s kinematics during discectomy according to operating table height and the methods to visualize the surgical field

The ergonomic problems for surgeons during spine surgery are an awkward body posture, repetitive movements, increased muscle activity, an overflexed spine, and a protracted time in a standing posture. The authors analyzed whole spine angles during discectomy. The objective of this study is to assess differences in surgeon whole spines angles according to operating table height and the methods used to visualize surgical field. A cohort of 12 experienced spine surgeons was enrolled. Twelve experienced spine surgeons performed discectomy using a spine surgery simulator. Three different methods were used to visualize the surgical field (naked eye, loupe, and out of loupe) and three different operating table heights. Whole spine angles were compared for three different views during discectomy simulation; midline, ipsilateral, and contralateral. A 16-camera optoelectronic motion analysis system was used, and 16 markers were placed from head to pelvis. Lumbar lordosis, thoracic kyphosis, cervical lordosis, and occipital angle were compared at the different operating table heights, while using the three visualization methods, with natural standing position. Whole spine angles were significantly different for visualization methods. Lumbar lordosis, cervical lordosis, and occipital angle were closer to natural standing values when discectomy was performed with a loupe, but most measures differed from natural standing values when performed out of loupe. Thoracic kyphosis was also similar to the natural standing position during discectomy using a loupe, but differed from the natural standing position when performed with naked eye. Whole spine angles were also found to differ from the natural standing position according to operating table height, and became closer to natural standing position values as operating table height increased, when simulation was conducted with loupe. This study suggests that loupe use and a table height midpoint between the umbilicus and sternum are optimal for reducing surgeon musculoskeletal fatigue.

Significance of the tentorial alignment in approaching the trigeminal nerve and the ventral petrous region through the suboccipital retrosigmoid technique

In this study, the authors aimed to identify the factors that would predict the operative distance between the trigeminal nerve (fifth cranial nerve) and the acousticofacial nerve complex (seventh-eighth cranial nerves) preoperatively when approaching the cerebellopontine angle (CPA) through the suboccipital retrosigmoid approach. In 40 consecutive patients who underwent microvascular decompression of the trigeminal nerve via a suboccipital retrosigmoid approach for trigeminal neuralgia, the following three parameters were assessed on preoperative magnetic resonance images: 1) the angle between the tentorium and the line drawn from the hard palate (tentorial angle); 2) the angle between the lines drawn along the petrous bones ventral to the internal auditory canals (petrous angle); and 3) the angle between the tentorium and the line connecting the opisthion to the inion (occipital angle). The distance between the trigeminal nerve and the acousticofacial nerve complex (referred to as "distance") was measured intraoperatively. Statistical analysis was performed using the Pearson correlation test. The mean values were 50.9 +/- 11.5 degrees for the tentorial angle, 102.5 +/- 13.1 degrees for the petrous angle, 83.4 +/- 9.7 degrees for the occipital angle, and 3.1 +/- 1.5 mm for distance. There was a strong inverse correlation between the tentorial angle and distance (r = -0.228, p = 0.08). The mean distance was 3.5 +/- 1.9 mm for a tentorial angle less than 51 degrees and 2.7 +/- 1.1 mm for a tentorial angle of at least 51 degrees. No correlation existed between either the petrous or occipital angles and distance. The distance between the trigeminal nerve and acousticofacial nerve complex decreases in the presence of a steep tentorial angle. This limits the operating field between these cranial nerves when reaching the petroclival or the superior CPA regions through the retrosigmoid approach. Awareness of such anatomical features at the time of preoperative planning is of paramount importance in selecting the optimum surgical approach and minimizing operative complications.

Significance of the Tentorial Alignment in Approaching the Trigeminal Nerve through the Suboccipital Retrosigmoid Technique

Introduction: In this study, we aimed at assessing the significance of the tentorial alignment in approaching the trigeminal nerve through a suboccipital retrosigmoid craniotomy. Methods: Four parameters were evaluated using preoperative MRI and intraoperative measurements in 34 consecutive patients who underwent microvascular decompression of the trigeminal nerve via a suboccipital retrosigmoid approach: (1) the angle between the tentorium and the line drawn from the hard palate (tentorial angle, TA); (2) the angle between the tentorium and the line connecting the opisthion to the inion (occipital angle, OA); (3) the angle between the lines drawn along the petrous bones ventral to the internal auditory canals (petrous angle, PA); (4) the intraoperative distance between the trigeminal nerve and the acousticofacial bundle (distance, d). Statistical analysis was performed using Pearson's correlation test and t-test as appropriate. Results: Mean values were 50.1 ± 12.2 for TA, 82.3 ± 9.9 for OA, 104.6 ± 12.2 for PA, and 3.2 ± 1.5 mm for d. There was a negative correlation between TA and d (r = − 0.233, p = 0.09): the mean d was 3.7 ± 1.7 mm for TA 51 (p = 0.06). A positive correlation was detected between TA and OA (r = 0.336, p = 0.02). Conclusions: The distance between the trigeminal nerve and the acousticofacial bundle decreases in the presence of a steep tentorial angle. This limits the working field at the petrotentorial sulcus. Awareness of such anatomical features at the time of preoperative planning is of paramount importance to avoid complications during the procedure.

Cerebral cortex three-dimensional profiling in human fetuses by magnetic resonance imaging.

Seven human fetuses of crown/rump length corresponding to gestational ages ranging from the 12th to the 16th week were studied using a paradigm based on three-dimensional reconstruction of the brain obtained by magnetic resonance imaging (MRI). The aim of the study was to evaluate brain morphology in situ and to describe developmental dynamics during an important period of fetal morphogenesis. Three-dimensional MRI showed the increasing degree of maturation of the brains; fronto-occipital distance, bitemporal distance and occipital angle were examined in all the fetuses. The data were interpreted by correlation with the internal structure as visualized using high-spatial-resolution MRI, acquired using a 4.7-T field intensity magnet with a gradient power of 20 G cm(-1). The spatial resolution was sufficient for a detailed detection of five layers, and the contrast was optimized using sequences with different degrees of T1 and T2 weighting. Using the latter, it was possible to visualize the subplate and marginal zones. The cortical thickness was mapped on to the hemispheric surface, describing the thickness gradient from the insular cortex to the periphery of the hemispheres. The study demonstrates the utility of MRI for studying brain development. The method provides a quantitative profiling of the brain, which allows the calculation of important morphological parameters, and it provides informative regarding transient features of the developing brain.