Posterior Fossa Structures Research Articles

Traumatic Delayed Posterior Cranial Fossa Epidural Hematoma: A Rare Entity

AbstractPosterior fossa epidural hematomas (EDHs) are much rarer entities than supratentorial EDHs which are reported only 4 to 7% in the literature. Due to the tight space and critical structures in posterior fossa, only a few cases can go with the conservative management but even then patients can deteriorate anytime with enlargement of hematoma and compression effects on brain stem and require urgent evacuation. This letter aims to provide a case of a young kid who presented initially with less-volume EDH and later required urgent evacuation because of hematoma expansion.

Кашлевая головная боль: клиника, диагностика, лечение

Cough headache can be primary, characterized by a benign course, or symptomatic, resulting from pathologies of the posterior cranial fossa structures. According to the latest classification of the International Headache Society (IHS), primary cough headache is included in the «other primary headaches» registry and is defined as headache provoked by coughing, sneezing, or straining during defecation in the absence of any intracranial disorders. Symptomatic cough headache due to Chiari malformation is considered under the rubric of «headache associated with nonvascular intracranial lesions» and classified as headache associated with Chiari malformation type I. Different types of cough headaches require careful differential diagnosis and different treatment approaches.

Movement Disorders in Brain Sagging Syndrome Due To Spontaneous Intracranial Hypotension: A Review.

Spontaneous intracranial hypotension (SIH), a treatable condition that stems from spinal leakage of cerebrospinal fluid, usually presents with orthostatic headache, nausea, vomiting, dizziness, and tinnitus. A subset of patients, especially those with sagging of brain structures ("brain sagging syndrome"), develop several movement abnormalities. As SIH is treatable with epidural blood patch (EBP), movement disorders neurologists should be familiar with this syndrome. The authors performed a literature search in PubMed in July 2024 using the Boolean phrase- (("Brain sagging")OR("Intracranial hypotension"))AND(((((((((("Movement disorders")OR("Involuntary movements"))OR("Tremor"))OR("Dystonia"))OR("Chorea"))OR("Ballismus"))OR("Myorhythmia"))OR ("Tic"))OR("Ataxia"))OR("Parkinsonism")). We tabulated 21 case reports/series that highlighted the presence of movement disorders. The most reported phenomenology is gait unsteadiness. While it usually emerges in the background of the classic SIH symptoms, rarely, patients may present with isolated gait dysfunction. Tremor is the second most reported phenomenology with postural and kinetic tremor being the common subtypes. Holmes tremor has also been reported in SIH. Other reported phenomenologies are parkinsonism, chorea, and dystonia. One study reported a unique phenomenology i.e. compulsive repetitive flexion and breath holding in 35.3% of the patients. In majority of the patients, EBP resulted in substantial clinical and radiological improvement. Brain sagging syndrome due to SIH may present with a wide range of movement disorders. Mechanical distortion of the posterior fossa and subcortical structures result in the emergence of such movement abnormality. SIH adds to the list of conditions that result in "treatable movement disorders." Therefore, movement disorders neurologists should be versed with the diagnosis and clinical features of this condition.

Growth patterns and ratios of posterior cranial fossa structures in the Japanese pediatric population: a study utilizing CT scans.

The changes in the proportion of posterior cranial fossa structures during pediatric development remain unclear. This retrospective study aimed to investigate the growth patterns and ratios of these structures using CT scans. Head CT scans of pediatric patients with minor head trauma from Osaka Women's and Children's Hospital between March 2006 and May 2023 were analyzed. The study segmented the intracranial volume (ICV), posterior cranial fossa volume (PCFV), cerebellum volume (CBMV), and brainstem volume (BSV). Correlation coefficients were calculated among the parameters. Patients aged 0 to 10 years were divided into 15 age-related clusters, and mean and standard deviation values were measured. Growth curves were created by plotting mean values sequentially. Ratios such as PCFV/ICV and (CBMV + BSV)/PCFV were examined. Statistical analyses, including unpaired t tests and logarithmic curve fitting, were performed. A total of 234 CT scans (97 from females, 115 from infants under 1 year of age) were analyzed. Positive correlations were observed among the parameters, with the strongest between PCFV and CBMV. The growth curves for ICV, PCFV, CBMV, and BSV exhibited a two-phase process, with rapid growth until approximately 4 years of age, followed by stabilization. The ratios PCFV/ICV and (CBMV + BSV)/PCFV showed increasing trends from birth onwards, stabilizing by 4 and 1 years of age, respectively. This study provides insights into the growth patterns and ratios of posterior cranial fossa structures in the pediatric population. The findings demonstrate a two-phase growth process and increasing trends in the examined ratios.

Interindividual differences in posterior fossa morphometry affect cerebellar tDCS-induced electric field strength

ObjectiveClinical, behavioural, and neurophysiological effects of cerebellar transcranial direct current stimulation (tDCS) are highly variable and difficult to predict. We aimed to examine associations between cerebellar tDCS-induced electric field strength, morphometric posterior fossa parameters, and skin-cerebellum distance. As a secondary objective, field characteristics were compared between cephalic and extracephalic electrode configurations. MethodsElectric field simulations of midline cerebellar tDCS (7 × 5 cm electrodes, current intensities of 2 mA) were performed on MRI-based head models from 37 healthy adults using buccinator, frontopolar, and lower neck reference electrodes. Average field strengths were determined in eight regions of interest (ROIs) covering the anterior and posterior vermis and cerebellar hemispheres. Besides skin-cerebellum distance, various angles were measured between posterior fossa structures. Multivariable linear regression models were used to identify predictors of field strength in different ROIs. ResultsSkin-cerebellum distance and “pons angle” were independently associated with field strength in the anterior and posterior vermis. “Cerebellar angle” and skin-cerebellum distance affected field strength in anterior and posterior regions of the right cerebellar hemisphere. Field strengths in all examined cerebellar areas were highest in the frontopolar and lowest in the lower neck montage, while the opposite was found for field focality. The lower neck montage induced considerably less spreading toward anterior cerebellar regions compared with the buccinator and frontopolar montages, which resulted in a more evenly distributed field within the cerebellum. ConclusionIn addition to skin-cerebellum distance, interindividual differences in posterior fossa morphometry, specifically pons and cerebellar angle, explain part of the variability in cerebellar tDCS-induced electric field strength. Furthermore, when targeting the midline cerebellum with tDCS, an extracephalic reference electrode is associated with lower field strengths and higher field focality than cephalic montages. SignificanceThis study identifies two novel subject-specific anatomical factors that partly determine cerebellar tDCS-induced electric field strength and reveals differences in field characteristics between electrode montages.

After the Knife: A Detailed Roadmap for Vestibular Schwannoma Resection in the Semi-Sitting Position – How I do it

Vestibular schwannoma surgery remains a neurosurgical challenge, with known risks, dependent on a number of factors, from patient selection to surgical experience of the team. The semi-sitting position has gained popularity as an alternative to the traditional supine position for vestibular schwannoma resection due to potential advantages such as improved surgical exposure due to clearer surgical field and anatomical orientation. However, there is a lack of standardized protocols for performing the procedure in the semi-sitting position, leading to variations in surgical techniques and outcomes. In this study, we aimed to establish a standardized approach for vestibular schwannoma resection using the semi-sitting position. Initiating after final position for semi-sitting, the authors have divided the surgical steps into five major parts for improved understanding and replication. Surgical techniques were analyzed through one hundred steps to identify commonalities, determining the optimal procedural steps for the semi-sitting position using surgical video for visual conceptualization. The analysis described one hundred steps for vestibular schwannoma resection in the semi-sitting position, with visual demonstration of the various parts of the procedure through surgical videos. Specific recommendations for each step were outlined, including appropriate approach, monitoring strategies, and tumor and posterior fossa structures manipulation. Five major parts of the procedure were identified, leading to a reproducible standardization of the surgical procedure of vestibular schwannoma resection in the semi-sitting position. This study provides a comprehensive standardized protocol for the semi-sitting procedure in vestibular schwannoma resection. By establishing a consistent approach, surgeons can minimize variations in surgical techniques and improve patient outcomes. The identified steps and recommendations can serve as a valuable resource for surgical teams involved in vestibular schwannoma resection and facilitate the dissemination and reproducibility of best practices.

Chiari Malformations: A Review of the Current Literature

Chiari malformations (CM) are a group of malformations involving the posterior fossa and rhombencephalic structures that may have other associated intra- or extracranial defects. Initially, the 4 classic varieties were described by the Austrian pathologist Hans Chiari towards the end of the 19th century; years later, the Swiss pathologist Julius Arnold described a case of type II CM with associated myelomeningocele. years later, two of his students used the term "Arnold-Chiari Malformation", this term is often misused for all types. Currently it is estimated that the incidence and prevalence data are underestimated due to the asymptomatic presentation of the pathology in many cases and the limited access to health services of different populations at a global level, for this reason the epidemiological data vary between the literature. The original classification has been modified by contributions from various authors in order to more precisely describe the variety of morphological findings; currently the classification includes CM types 0, I, 1.5, II, III and IV. The symptoms and associated pathological conditions vary for each type and type III and IV are the most severe forms. Diagnosis requires that secondary causes of cerebellar tonsillar ectopy (main finding of CM) be ruled out, along with a physical examination, neurological evaluation, and complementary tests; however, diagnosis requires resonance neuroimaging to demonstrate the findings. The management basically consists of performing a decompression of the posterior fossa and whose main indication is to reduce the symptoms, however, it should be noted that there is no global agreement among specialists on the subject of surgical management, for which each patient must be individualized by your treating physician and the decision made is subject to individual criteria.

Morphometric evaluation of cerebellar lobules in individuals with unilateral vertebral artery hypoplasia.

Vertebral arteries (VAs) provide blood circulation to the posterior fossa in general and are the main blood supply of the posterior fossa structures of the brain. Our aim in this study is to analyze the segmental volumetric values of cerebellar structures with the voxel-based volumetric analysis system in individuals with unilateral vertebral artery hypoplasia. In this retrospective study, segmental volumetric values/percentile ratios of cerebellar lobules were calculated using 3D fast spoiled gradient recall acquisition in steady-state (3D T1 FSPGR) MRI sequence images of the brain in individuals with unilateral vertebral artery hypoplasia (VAH) and in those without bilateral VAH and any symptoms of vertebrobasilar insufficiency as the control group was evaluated in volBrain ( http://volbrain.upv.es/ ). The VAH group consisted of 50 (19 males/31 females) and the control group had 50 (21 males/29 females) individuals. The cerebellar lobule III, IV, VIIIA and X total volumes and the cerebellar lobule I-II, III, IV, VIIIA and X gray matter volumes were lower in the hypoplastic side than the non-hypoplastic cases and also than the contralateral side of the hypoplastic cases in the VAH group. In addition, it was found that that lobules IV and V had lower cortical thickness and lobules I-II had a higher coverage rate in the intracranial cavity in the hypoplastic side than the non-hypoplastic cases and also than the contralateral side of the hypoplastic cases (p < 0.05). In this study, it was found that cerebellar lobule III, IV, VIIIA, X total volumes and cerebellar lobule I-II, III, IV, VIIIA, X gray matter volumes in addition to lobule IV, V cortical thicknesses were low in individuals with unilateral VAH. Being aware of these variations and taking them into account during future volumetric studies on the cerebellum are very important.

ARNOLD CHIARI-II MALFORMATION : A RARE CASE REPORT WITH PRENATAL SONOGRAPHIC FINDINGS.

Arnold chiari II malformation is a congenital CNS abnormality characterised by downward displacement of posterior fossa structures into spinal canal. This malformation is a causative factor of death in neonates and infants. A thorough understanding of the direct and indirect sonographic findings is necessary for the diagnosis of chiari II malformation in developing fetus.

Surgical management of Chiari malformation type 1 associated to MCAP syndrome and study of cerebellar and adjacent tissues for PIK3CA mosaicism

BackgroundSubjects with Megalencephaly-Capillary Malformation-Polymicrogyria syndrome (MCAP) can present with a Chiari Malformation Type 1 and resulting alterations in cerebrospinal fluid (CSF) dynamics, which may require surgical treatment. The aim of this paper is to describe the features of children with MCAP who underwent surgical decompression for CM1, and to explore the PIK3CA variant allele frequency (VAF) identified in cerebellar parenchyma and other adjacent structures. MethodsThis study reviewed two cases of children with CM1 and MCAP who underwent surgical decompression treatment. These two cases were part of a national cohort of 12 MCAP patients who had CM1, due to their surgical eligibility. Tissue samples were obtained from the cerebellar tonsils and adjacent anatomical structures during the surgical procedures. Samples were then subsequently analyzed for PIK3CA postzygotic variants. ResultsIn both cases, alterations in CSF dynamics, specifically hydrocephalus and syringomyelia, were observed and required surgical treatment. PIK3CA targeted sequencing determined the VAF of the postzygotic variant in both cerebellar and adjacent bone/connective tissues. DiscussionThe recognition of a CM1 comorbidity in MCAP patients is of paramount importance when considering personalized treatment options, especially because these patients are at higher risk of developing complications during surgical decompression surgery. The variable PIK3CA VAF identified in the different analyzed tissues might help explain the heterogeneous nature and severity of anomalies observed in the volume of the posterior fossa structures in MCAP patients and associated CSF and venous disorders.

Prenatal diagnosis of vermian cyst: a new type of posterior fossa cyst.

Prenatal diagnoses of cystic malformations of the posterior fossa mainly encompass arachnoid cysts, Blake's pouch cysts and Dandy-Walker syndrome. To date, vermian cysts have not been reported prenatally. To report a series of fetuses with a vermian cyst. This was a single-center retrospective study conducted from 2012 to 2021. We included all fetuses presenting with a vermian cyst and excluded all other types of posterior fossa cyst. The cyst was visible at prenatal ultrasound (US) and/or magnetic resonance imaging (MRI). Postnatal imaging and/or clinical outcome data were available. Sixteen fetuses fulfilled the inclusion criteria with a strong female predominance (n=13). US and MRI were performed at a mean gestational age of 29+5 and 33+1weeks, respectively. In all patients, the cyst was in the vermian horizontal fissure. The mean longest dimension was about 10mm. The vermis and other posterior fossa structures were otherwise normal. At postnatal imaging, 13 children underwent brain imaging including 11 MRIs with complete regression (n=9), stability (n=1) and increase in size (n=3) of the cyst. Psychomotor development was normal in 14 children. One child (with an inner ear malformation) showed a slight delay in walking and language acquisition. Slight walking ataxia was present in another child. We report 16 fetuses with posterior fossa cysts located within the vermis at the level of the horizontal fissure, diagnosed at US and/or MRI and carrying an overall excellent neurological prognosis.

Abstract 1122‐000148: Rare Anterior Inferior Cerebellar Artery Origin of Middle Meningeal Artery

Introduction : Middle meningeal artery (MMA) anatomy has very important surgical implications during endovascular and open based skull procedures. Various anatomical origins have been identified in the literature besides its most common origin as the largest branch of the maxillary artery. It runs parallel and close contact of the lateral skull face therefore during trauma to this area is prone to rupture resulting in subdural hemorrhage(SDH). In our case report, we present its peculiar origin from anterior inferior cerebellar artery which has never been reported before. The origin of MMA may reflects the risk involved with embolization therapy for chronic SDH. Methods : A case of MMA originated form AICA. A literature review was conducted of reports of MMA origins. Results : A 35‐year‐old male with a history of alcohol abuse presented to the ED after falling down from the stairs. In the ED, the patient had multiple episodes of seizures along with respiratory distress therefore was intubated due to concern of airway protection. CT head showed bilateral SDH. Patient underwent diagnostic angiogram for possible bilateral embolization of MMA. During the procedure, the left MMA origin was seen from the AICA whereas the right MMA arising from the external carotid artery. Embolization of the left MMA was aborted. Patient remained intubated and was later transferred to a long term care facility. Conclusions : In the last 80 years, the anatomy of the MMA has been part of the discussion of various literature. Seeger et.al, highlighted the embryological changes manifested as anastomosis between Sphenomaxillary artery and lateral pontine artery resulting in origin of MMA from Basilar artery along with absence of foramen spinosum. Since 1973, multiple literature highlighted the origin of MMA including the lacrimal artery, ICA, ascending pharyngeal artery, opthalmic and occipital arteries. Recently, In 2011 Kuruvuilla et.al showed the origin of MMA from posterior inferior cerebellar artery. MMA clinical significance can be seen in multiple diseases. Older populations with chronic subdural hematomas, embolization of MMA has shown to be a less invasive and cost effective procedure. In patients with anterior and middle cranial fossa meningiomas embolization of MMA has been a crucial part of management. Similarly, understanding of its anatomy is also important while treating MMA aneurysm or pseudoaneurysms. In our case, the origin of middle meningeal artery from AICA has been significant as it supplies the posterior fossa structures and was not reported in the literature before, hence the procedure was aborted. This anatomical variant has shown us a new light upon embryological evolution and has helped us widen the horizons of our approach towards brain vasculature. This finding will help the future Interventionists to develop new ways of embolization of the MMA and understanding its anatomy.

Hydranencephaly: A case report of A 32-year-old woman with preserved walking ability

Hydranencephaly is a rare post-neurulation disorder characterized by the extensive hemispheric destruction with preservation of diencephalic and posterior cranial fossa structures. Brain matter is mostly replaced with a membranous sac filled with cerebrospinal fluid.

The role of cochlear implant positioning on MR imaging quality: a preclinical in vivo study with a novel implant magnet system.

PurposesTo investigate the effects for Ultra 3D cochlear implant (CI) positioning on MR imaging quality, looking at a comprehensive description of intracranial structures in cases of unilateral and bilateral CI placement.MethodsFour CI angular positions (90°, 120°, 135° and 160°) at 9 cm distance from the outer-ear canal were explored. The 1.5 T MRI assessment included our institutional protocol for the investigation of brain pathologies without gadolinium application. Three investigators (two experienced neuroradiologists and one experienced otoneurosurgeon) independently evaluated the MR findings. A 4-point scale was adopted to describe 14 intracranial structures and to determine which CI positioning allowed the best image quality score and how bilateral CI placement modified MRI scan visibility.ResultsA high positive correlation was found between the three blinded observers. Structures situated contralateral from the CI showed high-quality values in all four placements. Structures situated ipsilaterally provided results suitable for diagnostic purposes for at least one position. At 90°, artifacts mainly involved brain structures located cranially and anteriorly (e.g., temporal lobe); on the contrary, at 160°, artifacts mostly influenced the posterior fossa structures (e.g., occipital lobe). For the bilateral CI condition, MR imaging examination revealed additional artifacts involving all structures located close to either CI, where there was a signal void/distortion area.ConclusionsSuitable unilateral CI positioning can allow the visualization of intracranial structures with sufficient visibility for diagnostic purposes. Bilateral CI positioning significantly deteriorates the anatomical visibility. CI positioning might play a crucial role for patients who need post-operative MRI surveillance.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00405-021-07005-y.

Immersive Surgical Anatomy of the Retrosigmoid Approach.

The retrosigmoid approach (RS) approach is the workhorse of the posterolateral neurosurgical techniques to access various posterior fossa structures and even extends into the middle fossa. Many studies have detailed two-dimensional (2D) descriptions of the RS technique from either the lateral or posterior view. This study is the first to provide a comprehensive analysis of the RS technique, soft tissue, extracranial landmarks, and intracranial structures of the posterolateral region using interactive three-dimensional (3D) volumetric models (VMs). The visuospatial understanding of the neuroanatomical structures and landmarks of the RS approach is critical for successful surgeries with minimal complications. This study aims to create a collection of VMs and stereoscopic media for the relevant layer-by-layer soft tissue anatomy and step-by-step surgical technique of the RS approach using cadaveric dissections. Five embalmed heads and one dry skull were used to generate stereoscopic images and VMs using 3D scanning technology (i.e., photogrammetry and structured light scanning) to illustrate and simulate the RS approach. The extracranial structures were divided into myofascial, superficial vascular, superficial nerve, and bony anatomy. The RS approach was divided into seven major steps: patient positioning, incision of the skin, dissection of the scalp flap, dissection of the muscles, craniotomy, dural opening, and closure.Additionally, we described an anatomical classification of surgical corridors based on the cisternal segments of the cranial nerves exposed during the RS approach. We discussed the nuances of the keyhole variations of the RS approach and intradural modifications of the RS approach using 3D VMs to illustrate the surgical corridors and the intradural structures accessed. These interactive VMs allow for clear visualization and dynamically immersive experience for neuroanatomical studies of the RS approach in 360-degrees and virtual reality (VR). Computer graphics can be implemented in neurosurgery to facilitate our topographic knowledge, which is crucial for anatomical education, surgical planning, intraoperative decision making, and postoperative care.

The executive functions, intellectual capacity, and psychiatric disorders in adolescents with Chiari malformation type 1.

In the last two decades, the non-motor functions of the cerebellum have become the centre of attention for researchers. Anecdotal observations of cognitive and psychiatric manifestations of cerebellar lesions have increased this interest. We aimed to investigate the executive function (EF), intellectual capacity, and comorbid psychiatric disorders in adolescents with Chiari malformation type 1 (CM1), which is a pathological manifestation of posterior cranial fossa structures include the cerebellum. The Chiari group consisted of ten adolescents aged 12-18 years old, and the control group consisted of 13 healthy adolescents with similar age and sex with patients. Stroop test (ST), trail making test (TMT), and Behaviour Rating Inventory of Executive Function-Parent form (BRIEF) were used to evaluate EF; Kent EGY and Porteus Maze Test was used to measuring the intelligence quotient (IQ), and a semi-structured interview was used to determine the psychiatric disorders. EF test scores were found comparable between the two groups. IQ scores of the Chiari group were found in the normal range, but significantly lower than controls. No significant difference was revealed in terms of comorbid psychiatric disorders between the two groups. In this study, we did not observe an impairing effect of CM1 on EF and intelligence. Also, we found that CM1 did not cause more psychiatric disorders compared to controls. Further studies need to support our findings in adolescents diagnosed with CM1.

Neuroanatomical MRI study: reference values for the measurements of brainstem, cerebellar vermis, and peduncles.

To set age-specific normal reference values for brainstem, cerebellar vermis, and peduncles measurements and characterize values' variations according to gender, age, and age by gender interaction. 565 normal brain magnetic resonance examinations with normal anatomy and signal intensity of the supra- and infratentorial structures were categorized into six age groups (infant, child, adolescent, young adult, middle-age adult, and old aged adults). Patients with congenital malformations, gross pathology of the supra- or infratentorial brain, brain volume loss, developmental delay, metabolic disorders, and neuropsychological disorders (n = 2.839) were excluded. On midsagittal T1 weighted and axial T2 weighted images specific linear diameters and ratios of the brainstem, cerebellar vermis, and peduncles were attained. Two observers assessed a random sample of 100 subjects to evaluate the inter- and intraobserver reproducibility. Intraclass correlation coefficients, means ± standard deviation, one and two-way analysis of variance tests were used in the statistical analysis. Good to excellent inter- and intraobserver measurements' reproducibility were observed, except for the transverse diameter of the midbrain, the anteroposterior diameter of the medulla oblongata at the pontomedullary and cervicomedullary junctions, cerebellar vermis anteroposterior diameter, and thickness of the superior cerebellar peduncle. Age-specific mean values of the investigated measurements were established. A significant gender-related variation was recorded in the anteroposterior diameter of the basis pontis (p = 0.044), the anteroposterior diameter of the medulla oblongata at the cervicomedullary junction (p = 0.044), and cerebellar vermis height (p = 0.018). A significant age-related change was detected in all measurements except the tectal ratio. Age by gender interaction had a statistically significant effect on the tectal ratio, inferior, and middle cerebellar peduncles' thickness (p = 0.001, 0.022, and 0.028, respectively). This study provides age-specific normal mean values for various linear dimensions and ratios of the posterior fossa structures with documentation of measurements' variability according to gender, age, and their interaction. It provides a valuable reference in the clinical practice for easier differentiation between physiological and pathological conditions of the posterior fossa structures especially various neurodegenerative diseases and congenital anomalies.

Utilization of SEMAC-VAT MRI for Improved Visualization of Posterior Fossa Structures in Patients With Cochlear Implants

The number of cochlear implant (CI) users is ever increasing worldwide, as is the utilization of magnetic resonance imaging (MRI) as a key diagnostic modality for pathology of the brain and surrounding structures. Despite advances in MRI compatibility with CI, metal artefact remains a significant issue that needs to be addressed. We test our hypothesis that the slice encoding for metal artefact correction and view angle tilting (SEMAC-VAT) metal artefact reduction technique improves demonstration of posterior fossa structures on MRI in CI recipients. A retrospective case review. A tertiary referral hearing implant and skull base center. Dedicated MRI of the posterior fossa using T1 spin echo post-gadolinium sequences with and without the application of SEMAC-VAT in CI recipients. Extent and severity of the artefact and visualization of surrounding anatomic structures with and without the application of SEMAC-VAT, allowing for direct comparison. Eight CI recipients with nine CI devices were analyzed. We noted a significant reduction in signal void and improved visibility of the ipsilateral hemisphere in every case. Penumbra size increased although there was improved visibility through the penumbra. There was improved visualization of key intracranial structures, such as the ipsilateral internal auditory canal, cerebellopontine angle, cerebellar hemisphere, and brainstem. Application of SEMAC-VAT produces a significant reduction in signal void and improved visualization of key structures within the temporal bone and posterior cranial fossa in patients with CIs without the need for removal of the internal magnet.

A Right Accessory Vertebral Artery and Variation in the Origin and its Entry to the Transverse Foramen

Variations of the vertebral artery origin are congenital abnormalities that occur during embryonic development. The vertebral artery origins from the superior part of the first part of the subclavian artery and it provides the main blood supply of the posterior cranial fossa structures. Several variations in the vertebral artery origin and its entry to the transverse foramen have been reported in advance. However, mention to the variation of the right vertebral artery origin and its entrance to the transverse foramen is rare. By describing dissection of an old man cadaver, two vertebral arteries were observed which were arised from the first part of the subclavian artery at the right side, and they follow a different direction to enter the transverse foramen. One of the arteries rises in its natural direction and enters into the transverse foramen of C6, and the other arteries take an abnormal direction upwards and then enter the higher level surface into the transverse foramen of C4. It is necessary to mention, the artery on the left was in its normal state. Regarding neck root surgery, knowing these variations reduces arterial injury during surgery and angiography.

Sonographic detection of fetal abnormalities before 11 weeks of gestation.

Sonographic detection of fetal abnormalities before 11 weeks of gestation.