Dorsum Sellae Research Articles

Supratotal Resection of Residual Clival Chordoma With Combined Endoscopic Endonasal and Contralateral Transmaxillary Approaches: 2-Dimensional Operative Video.

The optimal treatment for skull base chordomas is gross total resection followed by radiotherapy and not radiation of partially resected tumors. Supratotal resection, defined as removal beyond all involved bone and dura, is ideal but difficult to achieve. In this video, we present the case of a 37-yr-old man with new onset of progressive cranial nerve sixth palsy and a skull base lesion compatible with clival chordoma. He underwent partial surgical resection at an outside institution via transcranial approach, with significant tumor residual at the clivus, dorsum sella, posterior clinoids, and petrous apex, extensive dural invasion, and intradural extension with attachment to the basilar artery and its long perforating branches. Supratotal surgical resection was achieved using an endoscopic endonasal transclival approach, ipsilateral transpteryoid approach to the foramen lacerum for carotid artery mobilization, bilateral interdural transcavernous approach with posterior clinoidectomies, and con-tralateral transmaxillary approach to the petrous apex. Reconstruction was performed in a multilayer fashion with fascia lata and fat grafts, extended nasoseptal flap, a lumbar drainage for 3 d. No cerebrospinal fluid leak occurred, and the abducens nerve palsy significantly improved at 3-mo follow-up. Proton therapy is planned. Recent advances in endoscopic endonasal surgery allow for very high rates of complete and even supratotal resection despite the challenging location. A long learning curve to acquire the technical skills and complex surgical anatomy is required to decrease complication rates and achieve maximal resection in chordomas. Reoperations are more challenging and risky; therefore, first attempt should have curative intent. The patient signed informed consent including the use of photographic and video material for educational or academic purposes.

Accuracy of computed tomography: magnetic resonance imaging image fusion using a phantom for skull base surgery.

The aim of this study is to assess the positional accuracy of image fusions of the skull base region using different magnetic resonance imaging (MRI) and computed tomography (CT) image pairs. An image set of 3D fast imaging employing steady-state acquisition-C (FIESTA-C) was used as the base image set. Image fusions were performed using an image set with different fields of view (FOVs): one with different matrix size, one with a different sequence of 3D spoiled gradient recalled acquisition, and one with different modality (CT), using a phantom including multi columnar objects. Position of columns at the center, and 4 and 8 cm from the center were measured. The displacements between the base image set and fused image set were measured. For slices with different z-positions, the displacement of the 8-cm column was assessed. For 20 clinical MRI cases, the distance between the dorsum sellae and the cranial nerves was measured. No significant differences were found between the different FOVs or image sequences. However, with the different matrix sizes and modalities, significant displacements were observed, although they were all within 0.5 mm. Similar displacements were observed in the slices at different z-positions. All cranial nerves were located within 40 mm of the dorsum sellae. The displacements following image fusion were within approximately 0.5 mm, even at 8 cm from the center. This suggests that the region where the cranial nerves are located, within 40 mm of the dorsum sellae, had no risk of positional error following image fusion.

A DESCRIPTIVE RADIOGRAPHIC STUDY OF COMPOSITE IMAGES OBTAINED WITH THE PROMAX 3D IN THE ASSESSMENT OF THE MIDFACE

Ponte Academic JournalApr 2019, Volume 75, Issue 4 A DESCRIPTIVE RADIOGRAPHIC STUDY OF COMPOSITE IMAGES OBTAINED WITH THE PROMAX 3D IN THE ASSESSMENT OF THE MIDFACEAuthor(s): Ozlem Akkemik ,Kivanc Kamburoglu, Nuri Karabay, Hulya EllidokuzJ. Ponte - Apr 2019 - Volume 75 - Issue 4 doi: 10.21506/j.ponte.2019.4.3 Abstract:Objectives: To perform a descriptive radiographic study of stitched images of the midface obtained by Promax 3D Cone Beam Computed Tomography (CBCT) scanner in order to assess its potential uses. Methods: CBCT images of the maxillary area obtained by horizontal stitching of three full field of views (FOV) were selected retrospectively from the archives. Results: CBCT images from 47 subjects were retrieved. Of these, 25 structures of paranasal sinuses and 45 of the cranial fossa were bilaterally examined. The osteomeatal unit was defined on 84 sides. Superior attachments of the uncinate process were displayed on 33 sides. Fovea ethmoidalis was observed only on 10 sides. Ethmoid cells were visible on all scans. The frontal bone, the frontal sinus, crista galli and the cribriform plate were cut on 70, 64, 72 and 62 sides respectively. The greater wings were always observable. The lesser wing, anterior clinoid process, dorsum sellae, tuberculum sellae and optic canal were cut on 44, 40, 56, 55 and 40 sides, respectively. The squamous temporal bone was always visible except when it was fused with the parietal and the mastoid bone. The petrous apex was relatively well-defined on 19 sides. The relative foramina and carotid canal were observed in all of the images. Conclusions: Stitching images may help in the comprehensive evaluation of the maxillofacial region of patients with any pathology where involvement of the midface is suspected. Download full text:Check if you have access through your login credentials or your institution Username Password

Insights into cranial morphology and intraspecific variation from a new subadult specimen of the pan-cheloniid turtle <em>Euclastes wielandi</em> Hay, 1908

We describe a nearly complete skull and mandible of a subadult of Euclastes wielandi, a pan-cheloniid turtle recently recovered at the Jean and Ric Edelman Fossil Park at Rowan University in Mantua Township, New Jersey, which yields new information about the osteology, ontogeny, and intraspecific variation of this taxon. The specimen was collected from the earliest Danian Main Fossiliferous Layer (MFL) of the Hornerstown Formation. Although discovered immediately adjacent to remains of two pleurodires, Taphrosphys sulcatus and Bothremys sp., the skull and mandible can be definitively assigned to Pan-Cheloniidae based on its V-shaped basisphenoid and rod-like rostrum basisphenoidale. Among three pan-cheloniid taxa known from the MFL, the specimen is assigned to Eu. wielandi based on its low skull with dorsally-directed orbits, symphyseal swelling in the mandibular triturating surface, and high dorsum sellae. Comparisons with other specimens of Eu. wielandi and adults and juveniles of other pan-cheloniids revealed variations in the type and timing of cranial ontogenetic changes in the clade, as well as anatomical traits subject to intraspecific variation, such as the depth of the sella turcica, paths of the foramina nervi hypoglossi, and development of a precolumellar fossa. The relative contribution of the frontal to the orbital margin and precise path of the prefrontal-supraorbital scale sulcus are subject to individual variation in Eu. wielandi, as well as ontogenetic variation and bilateral asymmetry in other cryptodirans, signifying that the widespread use of frontal retraction in taxon diagnoses and as a phylogenetic character should be reconsidered. As in multiple other taxa, the mandibular triturating surface expands through growth in Eu. wielandi, demonstrating that increased durophagy with age was a common life strategy among Cryptodira.

The relationship of the basilar artery bifurcation and dorsum sel­lae

Aims: The aim of the study was to assess the position of the terminal basilar artery bifurcation (BAB) in relation to the dorsum sellae (DS) based on computed tomography scans of the head. The BAB is in most cases formed by two P1 segments of the posterior cerebral arteries at the level of the interpeduncular fossa, in close proximity to the DS. This type of division is called bifurcation. Numerous pathologies may develop in this region, including BAB aneurysms, which account for 5–8% of all intracranial aneurysms. The literature states that the position of an aneurysm in relation to the DS plays a significant role in planning surgical strategies for BAB aneurysms. Materials and methodology: The study involved 100 computed tomography angiography (CT angiography) scans of 54 women and 46 men aged 18–88 years (mean age 52.49 years). Multiplanar reconstructions were used. The position of the BAB in relation to the sagittal midline plane (MP) and the lowest DS point (LDSP) in the transverse plane (TP) was analysed in the coronal section. The distance between the BAB and DS was measured in the sagittal section. Results: In the studied patients ( n = 100), the BAB was located on the right of the MP in 57% of cases, on the left of the MP in 41% of cases and in the midline or median position in 2% of cases. The BAB was located above the LDSP (TP) in 47% of cases, and below it in 53% of cases. There were no cases of the BAB located in the TP. The average distance between the BAB and MP was 0.35 mm, SD 1.91 mm, and the average distance between the BAB and the TP was 1.01 mm, SD 4.47 mm. Moreover, the average distance between the BAB and the DS was 9.34 mm, SD 2.61 mm. Conclusions: The study revealed no statistically significant differences in BAB position depending on gender. However, a highly significant difference and higher location of the BAB in relation to the TP (in relation to the DS) was observed in persons older than 45 years of age.

Morphometric analysis of the sella turcica in Turkish individuals with different dentofacial skeletal patterns.

The aim of this study was to evaluate the morphometric analysis of sella turcica in a Turkish population according to gender, age, and dentofacial skeletal type and to investigate the prevalence of sella turcica shapes in different dentofacial skeletal types. The lateral cephalometric radiographs of 362 patients (145 males, 217 females) were included and grouped by age, gender, and dentofacial skeletal patterns. Linear dimensions of sella turcica, which include the length, height, and diameter, were measured, and the shapes of sella turcica were evaluated. The anatomical variants of the sella turcica in this study were normal morphology (39.0%), followed by pyramidal shape (15.5%), double contour of floor (14.6%), oblique anterior wall (14.4%), irregular dorsum sella (8.6%), and sella turcica bridge (8.0%). Significant differences were found between sella turcica shapes and dentofacial skeletal types (p < 0.01). Females had greater diameter size of sella turcica than males (p < 0.01). In addition, the subjects in the 15-21 age group had larger sella turcica depths and diameters than the subjects in the 9-14 age group (p < 0.05 and p < 0.01, respectively). However, no significant differences were found between age groups in terms of sella turcica lengths (p > 0.05). Results from this study showed that the sample had a higher rate of morphological variation (39% normal, 61% other types) in comparison with other populations or ethnic groups. The class III patients had more irregularity (notching) types in the posterior part of the dorsum sella and fewer oblique anterior wall types than the others. Linear dimensions and morphological types of sella turcica in this study can be used as reference for additional investigators, such as radiologists, orthodontists, maxillofacial surgeons, and neurosurgeons, to interpret and plan surgical procedures involving the sellar region.

Complications Associated With Transsphenoidal Pituitary Surgery: Review of the Literature.

Complications Associated With Transsphenoidal Pituitary Surgery: Review of the Literature.

Assessment of the endoscopic endonasal approach to the basilar apex region for aneurysm clipping.

The expanded endoscopic endonasal approach (EEA) has shown promising results in treatment of midline skull base lesions. Several case reports exist on the utilization of the EEA for treatment of aneurysms. However, a comparison of this approach with the classic transcranial orbitozygomatic approach to the basilar apex (BAX) region is missing.The present study summarizes the results of a series of cadaveric surgical simulations for assessment of the EEA to the BAX region for aneurysm clipping and its comparison with the transcranial orbitozygomatic approach as one of the most common approaches used to treat BAX aneurysms. Fifteen cadaveric specimens underwent bilateral orbitozygomatic craniotomies as well as an EEA (first without a pituitary transposition [PT] and then with a PT) to expose the BAX. The following variables were measured, recorded, and compared between the orbitozygomatic approach and the EEA: 1) number of perforating arteries counted on bilateral posterior cerebral arteries (PCAs); 2) exposure and clipping lengths of the PCAs, superior cerebellar arteries (SCAs), and proximal basilar artery; and 3) surgical area of exposure in the BAX region. Except for the proximal basilar artery exposure and clipping, the orbitozygomatic approach provided statistically significantly greater values for vascular exposure and control in the BAX region (i.e., exposure and clipping of ipsilateral and contralateral SCAs and PCAs). The EEA with PT was significantly better in exposing and clipping bilateral PCAs compared to EEA without a PT, but not in terms of other measured variables. The surgical area of exposure and PCA perforator counts were not significantly different between the 3 approaches. The EEA provided better exposure and control if the BAX was located ≥ 4 mm inferior to the dorsum sellae. For BAX aneurysms located in the retrosellar area, PT is usually required to obtain improved exposure and control for the bilateral PCAs. However, the transcranial approach is generally superior to both endoscopic approaches for accessing the BAX region. Considering the superior exposure of the proximal basilar artery obtained with the EEA, it could be a viable option when surgical treatment is considered for a low-lying BAX or mid-basilar trunk aneurysms (≥ 4 mm inferior to dorsum sellae).

Morphometry of the posterior clinoid process and dorsum sellae

Aims: The posterior clinoid process (PCP) is a paired anatomic structure located in the middle cranial fossa on the superior surface of the sphenoid bone where it forms a bony eminence that is the lateral boundary of the dorsum sellae (DS). The aim of the study was to analyze PCP and DS morphometry in computed tomography (CT) . Materials and methodology: The study was based on 100 CT investigations of 54 women and 46 men aged 18–88 (mean age 52.49 years). The PCP and DS morphometry was studied in coronal and sagittal planes. Data were analyzed statistically in relation to patients ’ gender and age (group 1: up to 45 years, group 2: over 45 years). Results: The average width of the right and left PCP was 10.2 mm and 9.85 mm, respectively, while the average height of the right and left PCP was 2.32 mm and 2.04 mm, respectively. The thickness of the DS superior edge was 3.29 mm, and of the right and left PCP: 4.28 mm and 4.31 mm, respectively. Statistical calculations lead to the conclusion that the right PCP is wider and thicker in men. Moreover, the DS superior edge is also thicker in men, and the left PCP is wider and higher in people over 45 years of age. Conclusions: The PCP and DS are characterized by considerable individual variability. CT is a useful modality for PCP and DS morphometry assessment. PCP and DS are different in men and women. Age affects skull base morphometry.

Prognosis of dolichoectasia in non-cardioembolic transient ischemic attack and minor stroke

Objectives This study aimed to estimate the prognosis of dolichoectasia in non-cardioembolic transient ischemic attack (TIA) and minor stroke patients.Methods Data were derived from the imaging subgroup of patients in the Clopidogrel in High-risk Patients with Acute Nondisabling Cerebrovascular Events (CHANCE) trial. Dolichoectasia was defined as ectasia (basilar artery diameter >4.5 mm) and dolichosis (either basilar artery bifurcation above the suprasellar cistern or lateral to the margin of the clivus or dorsum sellae). The prognosis included ischemic stroke recurrence and poor functional outcome (modified Rankin scale 2–6) at 12-month follow-up. The association of dolichoectasia with risk factors and prognosis of patients were assessed using multivariable Cox regression models.Results Overall, 1089 patients with magnetic resonance images in the CHANCE trial were included in this subanalysis. A total of 98 (9.0%) patients were detected with dolichoectasia, and 106 (9.7%) patients had a recurrent ischemic stroke at 12 months. Small artery occlusion (SAO) was more prevalent in patients with dolichoectasia compared with those without dolichoectasia (29.6% vs. 22.7%, hazard ratio [HR] 2.87, 95% confidence interval [CI] 1.59–5.17, p < 0.001). However, multivariate analysis showed no association of dolichoectasia with 12-month recurrent stroke (9.2% vs. 9.8%, HR, 1.15; 95%CI, 0.32–4.12; p = 0.83) and poor functional outcome (7.6% vs. 8.4%, odds ratio, 1.22; 95%CI, 0.24–6.08; p = 0.81) in the current subgroup analysis.Conclusions Dolichoectasia was significantly associated with SAO. There was no relationship between dolichoectasia and 12-month prognosis of patients with non-cardioembolic TIA or minor stroke.

Endoscopic Endonasal Resection of a Suprasellar Pituitary Adenoma Mimicking Tuberculum Sellae Meningioma in a Patient with an Intrasellar Persistent Trigeminal Artery

A 50-year-old female with an incidentally diagnosed suprasellar lesion was initially managed conservatively due to the presence of an intrasellar persistent trigeminal artery going through the dorsum sellae and fundamentally forming the blood supply of the entire posterior circulation. Serial follow-up brain magnetic resonance imaging (MRI) revealed progressive enlargement of the suprasellar lesion over 4 years period. Surgery was indicated after the initial tumor growth; however, the patient refused surgery for fear of complications related to the persistent trigeminal artery. Two-and-a-half years later, she presented with deterioration of vision. Formal visual field testing revealed a right temporal field defect. Brain MRI demonstrated significantly enlarged suprasellar lesion, most consistent with tuberculum sellae meningioma, exerting mass effect on the optic apparatus. The patient underwent endoscopic endonasal resection of the lesion through a transplanum/transtuberculum approach. Intraoperatively, absence of hypertrophic McConnel arteries, hyperostosis, and the fact that the dura was soft and not under tension was against the diagnosis of tuberculum sellae meningioma. Additionally, the tumor consistency was similar to a pituitary adenoma. A complete resection was accomplished and multilayer skull base reconstruction was performed with no complications. On postoperative day 1 (POD 1), she was operated upon for the evacuation of small suprasellar hematoma associated with vision deterioration. Histopathological examination confirmed the diagnosis of atypical pituitary adenoma with K i -67 labeling index of 4 to 5%. The patient ultimately recovered well with improved vision, and was discharged on POD 4 with no new neurological deficits. At 4 years follow-up, her vision was normalized and brain MRI showed no residual or recurrent lesion. The link to the video can be found at: https://youtu.be/QZmzctjAEbw .

A historical recount of chordoma.

Chordoma, a rare bone tumor that occurs along the spine, has led scientists on a fascinating journey of discoveries. In this historical vignette, the authors track these discoveries in diagnosis and treatment, noting events and clinicians that played pivotal roles in our current understanding of chordoma. The study of chordoma begins in 1846 when Rudolf Virchow first observed its occurrence on a dorsum sellae; he coined the term "chordomata" 11 years later. The chordoma's origin was greatly disputed by members of the scientific community. Eventually, Müller's notochord hypothesis was accepted 36 years after its proposal. Chordomas were considered benign and slow growing until the early 1900s, when reported autopsy cases drew attention to their possible malignant nature. Between 1864 and 1919, the first-ever symptomatic descriptions of various forms of chordoma were reported, with the subsequent characterization of chordoma histology and the establishment of classification criteria shortly thereafter. The authors discuss the critical historical steps in diagnosis and treatment, as well as pioneering operations and treatment modalities, noting the physicians and cases responsible for advancing our understanding of chordoma.

Pneumatization of the sphenoid sinus, dorsum sellae and posterior clinoid processes in computed tomography

PurposeAssessment of sphenoid sinus (SS), posterior clinoid process (PCP), and dorsum sellae (DS) pneumatisation is significant when planning surgical approaches both to intra- and extrasellar pathologies. The authors analysed pneumatisation of the SS, with particular attention paid to pneumatisation of the PCP and DS.Material and methodsThe study was based on 100 computed tomography angiography examinations. SS, PCP, and DS pneumatisation grades were assessed using the classification system proposed by Hardy. The analyses were conducted in sagittal planes: midline plane (MP), sagittal posterior clinoid plane right (SPCP-R), and sagittal posterior clinoid plane left (SPCP-L). The occurrence of the highest pneumatisation grade (IVB according to Hardy), which encompasses DS and PCP, prompted the authors to conduct a further analysis in the coronal plane. In this way, seven DS and PCP pneumatisation symmetry types were identified.ResultsIn the MP and SPCP-R, the most frequent pneumatisation grade was grade III (41% and 38%, respectively). In the SPCP-L, grade IVA prevailed (41%). Grade IVB was found in 12% of the SPCP-R images, 10% of the SPCP-L images, and in 12% of the MP images. Consistent pneumatisation grades in all analysed planes were found for 64% of cases. This was usually grade III noted in 28% of cases.ConclusionsSS pneumatisation is characterised by considerable individual variability. There are a number of SS pneumatisation classification systems, but the system proposed by Hardy is the most useful for assessment of DS and PCP pneumatisation. Grade III of SS pneumatisation is the most common. Pneumatisation encompassing DS and PCP was found in 10-12% of cases.

Pons ratio as a potential diagnostic biomarker for the detection of growth hormone deficiency in children.

Pituitary insufficiency (PI) needs further research to optimize treatment. Growth hormone deficiency (GHD) is a subtype of PI. The purpose of the present study is to investigate the possible relationship between GHD and the anatomical position of the pons as revealed by magnetic resonance imaging (MRI) in the pediatric age group. In the current study, we developed a novel and simple index using MRI that could provide an alternative to other indexes in the classical literature. Brain MRI and clinical data of 48 children with suspected PI (22 females, 26 males; mean age 11.6 ± 2.2 years) were examined retrospectively. To estimate the location of the pons, the ratio of pons height over the axis between the dorsum sellae and the fourth ventricular hill in the sagittal plane (A) to the total height of the pons (B) was calculated (A/B). It was termed the pons ratio (PR). The PRs of children with or without a diagnosis of GHD were then compared statistically. Fifteen children were diagnosed with GHD and treated with growth hormone (GH), whereas the remaining 33 were reported normal. The mean PRs of the children diagnosed with GHD and given GH treatment (0.31 ± 0.07, range: 0.18-0.42) differed significantly from those without PI (0.26 ± 0.06, range: 0.17-0.44; P = 0.018). There appears to be an association between GHD and decreased PR in children receiving GH treatment. Spatial measurements of posterior fossa in radiological examinations may provide additional information that is helpful in the diagnosis of suspected cases of GHD.

Volumetric assessment of sphenoid sinuses through segmentation on CT scan.

Computed tomography represents the gold standard for the assessment of morphological characteristics of sphenoid sinuses, whose anatomy has acquired a novel interest because of the recent introduction of transsphenoidal surgery and robot-assisted procedures. One of the most relevant parameters for planning surgical intervention is the volume of sphenoid sinuses, and with time few population studies have been published. However, at present, no data are available concerning the relation between volume and anatomical variants of sphenoid sinuses. We retrospectively evaluated head CT-scans of 100 patients (age range 25-99years; mean age males 45.0; mean age females 50.5years) to calculate the volume of sphenoid sinuses through automatic segmentation. Possible statistically significant differences according to sex and variants of pneumatization, and type of sinus were assessed, respectively, through Student's t test and one-way ANOVA test (p < 0.05). Average volume of sphenoid sinuses in males was 10.005 ± 5.101cm3, in females 7.920 ± 3.176cm3. Differences according to sex were statistically significant (p < 0.05). Patients with pneumatization of pterygoid processes, dorsum sellae and anterior clinoid processes had a significantly higher volume than unaffected subjects. Moreover, differences of volume according to the type of sphenoid sinus were statistically significant (p < 0.05). Results show that volume of sphenoid sinuses strongly depend upon the type of sinus and possible pneumatization variants. Moreover, the important of ethnic variability is confirmed.

Introduction: surgical management of skull base meningiomas.

Meningiomas represent the most common primary intracranial neoplasm treated by neurosurgeons. Although multimodal treatment of meningiomas includes surgery, radiation-based treatments, and occasionally medical therapy, surgery remains the mainstay of treatment for most symptomatic meningiomas. Because of the intricate relationship of the dura mater and arachnoid mater with the central nervous system and cranial nerves, meningiomas can arise anywhere along the skull base or convexities, and occasionally even within the ventricular system, thereby mandating a catalog of surgical approaches that neurosurgeons may employ to individualize treatment for patients. Skull base meningiomas represent some of the most challenging pathology encountered by neurosurgeons, on account of their depth, invasion, vascularity, texture/consistency, and their relationship to bony anatomy, cranial nerves, and blood vessels. Resection of complex skull base meningiomas often mandates adequate bony removal to achieve sufficient exposure of the tumor and surrounding region, in order to minimize brain retraction and optimally identify, protect, control, and manipulate sensitive neurovascular structures. A variety of traditional skull base approaches has evolved to address complex skull base tumors, of which meningiomas are considered the paragon in terms of both complexity and frequency. In this supplemental video issue of Neurosurgical Focus, contributing authors from around the world provide instructional narratives demonstrating resection of a variety of skull base meningiomas arising from traditionally challenging origins, including the clinoid processes, tuberculum sellae, dorsum sellae, petroclival region, falco-tentorial region, cerebellopontine angle, and foramen magnum. In addition, two cases of extended endoscopic endonasal approaches for tuberculum sellae and dorsum sellae meningiomas are presented, representing the latest evolution in accessing the skull base for selected tumors. Along with key pearls for safe tumor resection, an equally important component of open and endoscopic skull base operations for meningiomas addressed by the contributing authors is the reconstruction aspect, which must be performed meticulously to prevent delayed cerebrospinal fluid leakage and/or infections. This curated assortment of instructional videos represents the authors' optimal treatment paradigms pertaining to the selection of approach, setup, exposure, and principles to guide tumor resection for a wide spectrum of complex meningiomas.

Morphological variation of the caudal fossa of domestic cat skulls assessed with CT and geometric morphometrics analysis.

Objectives This study aimed to investigate differences and demonstrate a normal range of morphological variation of the caudal fossa of the cranium of domestic cats. Methods CT scans of 32 domestic cat heads of 11 breeds were included. Isosurfaces from skulls were characterised through three-dimensional geometric morphometrics using geographical landmarks placed on the internal surface of the caudal fossa and foramen magnum. Raw data was transformed with a Procrustes fit and coordinate covariance was analysed by principal components to establish breed- and sex-level differences. Skulls were also classified according to the number of concavities along the mid-sagittal vermiform impression. Differences were investigated between breed groups and sex, and correlation was sought with age. Results Analyses revealed size-independent differences in occipital bone morphology across breeds and sex; however, no clustering was evident. Most variability was observed at the exoccipital bones, ventral portion of the supraoccipital bone, dorsum sellae of the basisphenoid and the osseous tentorium cerebelli. No statistically significant differences were identified via two-sample t-tests between breed groups or sexes. No statistically significant correlation using Spearman rho correlation coefficient was identified with age. Conclusions and relevance The feline caudal fossa displays a wide range of intra- and inter-breed variation, not linked to age or sex. Concavities along the vermiform impression have not previously been described. As advanced imaging modalities are becoming more frequently used for domestic felids, an established range of normality is important for discriminating pathological changes from anatomical variances.

PB 3 Abnormal height of basilar artery bifurcation in adults with Pompe disease

Introduction The evidence for an involvement of the cerebral arteries in adults with Pompe disease is increasing.Typical changes are dilation, elongation and distension of the vertebrobasilar arteries ( [Laforet et al., 2008] , [Sacconi et al., 2010] , [Hensel et al., 2014] , [Montagnese et al., 2016] ). Methods In 15 adults with Pompe disease (age 57 ± 13 years, 8 females) and 12 controls with comparable age and cardiovascular risk factors (age 53 ± 6 years, 4 females) the cerebral arteries were examined with a time of flight MR-angiography.The angle of departure of the superior cerebellar artery (SUCA) was measured from the basilar artery (BA) ( Figs.1 and 2 ).In addition, the level of the bifurcation of the BA was evaluated by a Smoker’s criteria based definition ( Smoker et al., 1986 ) (score at or below the dorsum sellae, score 1 within suprasellar cistern, score 2 at the level of third ventricle floor, score 3 indenting and elevating floor of third ventricle). Results In adults with Pompe disease the angle of SUCA departure was 59° (sum left and right 119°, controls: left 75° and right 83°, sum 159°).Compared with a preliminary MR-angiography five years before ( Hensel et al., 2014 ) the angle of departure decreased from 5 to 11° (n = 5 patients).In 11/15 Pompe patients, the bifurcation of the BA was abnormally high (Smoker score 0: 0 patients, score 1: 4 patients, score 2: 5 patients and score 3: 6 patients).In controls this was rarer and less pronounced (Smoker score 0: 6 patients, score 1: 5 patients, score 2: 0 and score 3: 1 patient).The Smoker score was lower among young Pompe patients than in older patients.In 7/15 (47%) of Pompe patients and in 1/12 (8%) of the controls the proximal posterior cerebral artery (PCA) indenting the hypothalamus (arrow in Fig.3 ).One patient developed a hemorrhage in the thalamus, which was supplied by the displaced superiorly PCA. Discussion The results indicate a upwards displacement of the distal basilar artery in adults with Pompe disease.Such upwards displacement in patients with dolichoectasia of other origin is associated with any stroke and subsequently increased dolichoectatic progress ( Passero and Rossi, 2008 ). In our patients the degree of displacement increases with patient age or duration of the disease. These could represent an accelerated destruction of vertebrobasilar arteries in adults with Pompe disease. The abnormal height of basilar bifurcation could represent an early and easy recognizable sign for cerebrovascular involvement as well.

Basilar Artery Dolichoectasia: Prevalence and Correlates With Markers of Cerebral Small Vessel Disease in Community-Dwelling Older Adults

Basilar artery (BA) dolichoectasia has been associated with cerebral small vessel disease (SVD). However, studies have focused on stroke patients, and results cannot be extrapolated to the population at large. In this study, we aimed to assess prevalence of BA dolichoectasia and its association with SVD in community-dwelling older adults living in rural Ecuador. Atahualpa residents aged ≥60 years underwent brain magnetic resonance imaging and magnetic resonance angiography of intracranial vessels. Following Smoker's criteria, the mean BA diameter plus 2 standard deviation defined ectasia. In addition, a location lateral to the lateral margin of the clivus of dorsum sellae or a bifurcation at the third ventricle floor or higher defined dolichosis. Associations between BA abnormalities and imaging markers of SVD were assessed by the use of regression models adjusted for demographics and cardiovascular risk factors. Of 346 participants, 11 (3.2%) had ectasia, 40 (11.6%) had dolichosis, and 47 (13.6%) had dolichoectasia (ectasia, dolichosis, or both). BA diameter was only associated with severity of white matter hyperintensities (P = .038). Dolichosis was associated with deep cerebral microbleeds (P = .002) but not with white matter hyperintensities. Dolichoectasia was associated with both white matter hyperintensities (P = .031) and cerebral microbleeds (P = .001). There were no associations with lacunar infarcts or enlarged perivascular spaces in any model. Prevalence of BA dolichoectasia in this rural setting is similar to that reported in other populations. Associations with imaging markers of SVD differ according to whether the subject has ectasia or dolichosis.

The Interlenticulostriate Approach to Very High-Riding Distal Basilar Trunk Aneurysms.

Most high-riding distal basilar trunk aneurysms can be surgically approached via the transsylvian route and its orbitozygomatic variant. However, on rare occasions, the basilar bifurcation may be unusually high and an approach above the carotid terminus may be required. In this cadaveric study, we sought to determine the feasibility and exposure limits of the interlenticulostriate approach (ILSA). A standard transsylvian approach was performed in 10 cerebral hemispheres of 5 formalin-fixed, silicone-injected cadaver heads. The interpeduncular cistern was exposed via the opticocarotid window, carotid-oculomotor window, and supracarotid ILSA window. The latter was measured and an aneurysm clip or ventriculostomy stylet was placed as high as possible through each corridor. Using noncontrast 3-D rotational angiography, clip/stylet positions were measured relative to the dorsum sellae. ILSA provided a 9.4 × 4.6 mm mean surgical corridor, just enough room for a standard clip applier. This space was limited by the carotid bifurcation inferiorly, the lenticulostriate arteries medially and laterally, and the optic tract superiorly. There was no difference between opticocarotid and carotid-oculomotor windows, in terms of clip position (+8.9 vs +8.6 mm, respectively; P = .78). In contrast, ILSA provided significantly improved superior exposure, compared with either approaches (mean stylet position: +14.3 mm; P = .005). The exposure benefit afforded by ILSA was consistent across all 10 hemispheres, ranging from +2.5 to +8 mm. For high-riding distal basilar trunk aneurysms that cannot be reached via the frontotemporal orbitozygomatic approach, ILSA can provide a viable route of access. Vascular neurosurgeons should be familiarized with this approach.