Lateral Foramen Research Articles

The presence of a foramen of Luschka in the American alligator (Alligator mississippiensis) and the continuity of the intraventricular and subdural spaces.

In humans and most mammals, there is a notch-like portal, the foramen of Luschka (or lateral foramen), which connects the lumen of the fourth ventricle with the subdural space. Gross dissection, light and scanning electron microscopy, and μCT analysis revealed the presence of a foramen of Luschka in the American alligator (Alligator mississippiensis). In this species, the foramen of Luschka is a notch in the dorsolateral wall of the pons immediately caudal to the peduncular base of the cerebellum, near the rostral end of the telovelar membrane over the fourth ventricle. At the foramen of Luschka there was a transition from a superficial pia mater lining to a deep ependymal lining. There was continuity between the lumen of the fourth ventricle and the subdural space, via the foramen of Luschka. This anatomical continuity was further demonstrated by injecting Evans blue into the lateral ventricle which led to extravasation through the foramen of Luschka and pooling of the dye on the lateral surface of the brain. Simultaneous subdural and intraventricular recordings of cerebrospinal fluid (CSF) pressures revealed a stable agreement between the two pressures at rest. Perturbation of the system allowed for static and dynamic differences to develop, which could indicate varying flow patterns of CSF through the foramen of Luschka.

Radiological and Morphometric Study of the Emissary Foramens and Canal in the Posterior Cranial Fossa of the Human Skull with Its Neurosurgical Significance.

Objective The posterior condylar canals (PCCs), posterior condylar veins (PCVs), occipital foramen (OF), and occipital emissary vein (OEV) are potential anatomical landmarks for surgical approaches through the lateral foramen magnum. We performed the study to make morphometric and radiological analyses of the various emissary foramens and vein in the posterior cranial fossa. Methods Morphometric study were performed on 95 dry occipital bones and radiological analyses on computed tomography (CT) angiography images of 150 patients. The number of OFs on both sides was recorded and PCC length and mean diameters of the internal and external orifices of PCC were measured for bony specimens. Prevalence of PCV and PCV size was investigated using CT angiography. Results Mean PCC length was higher in the left side (9.85 ± 2.5). Mean diameter of the internal orifice and the external orifice diameter were almost the same. The majority of PCCs (75-79.33%) had 2 to 5 mm diameter; only 4 to 9.2% were small in size (< 2 mm). In CT angiography, PCV was not identified in 23 (15.33%) patients. PCVs were located bilaterally in 105 (70%) and unilaterally in 22 (20.5%) patients. Only 11.3% of PCVs were large in size (> 5 mm), 80% of PCVs were medium sized (2-5 mm), and 8.6% were small sized (< 2 mm). Conclusion Normal values of OF, PCC, PCV, and OEV could serve as a future reference for the understanding of the physiology of craniocervical venous drainage, which is necessary to avoid surgical complications and can also serve as a guide to surgical interventions for pathologies of the posterior cranial fossa, such as tumors and injuries.

Dural arteriovenous fistulae at the lateral foramen magnum: A series of two microsurgical cases

AbstractAimTo study specific vascular anatomy of dural arteriovenous fistulae (DAVFs) locating at the foramen magnum in patients admitted to our centre in the past year (2019–2020), and to evaluate effectiveness of microsurgical disconnection of DAVFs alone.Patients and MethodsTwo male patients were included. Neuroimaging results obtained on admission, including computer tomography, digital subtraction angiography and magnetic resonance imaging of the brain, were studied and compared. Digital subtraction angiography with selective injection to the external carotid artery was particularly explored to trace main feeding arteries and draining veins of DAVFs.ResultsBoth patients had diffuse subarachnoid haemorrhage (SAH), particularly anterior to the medulla on initial computer tomography of the brain. Branches of the ascending pharyngeal artery were identified as main feeding arteries. Draining veins included anterior/posterior spinal veins and pterygopalatine venous plexus. Magnetic resonance imaging confirmed DAVFs at the level of foramen magnum to C1 vertebra. Complete occlusion was achieved with far‐lateral microsurgical approach, with intra‐operative indocyanine green injection confirming no filling of venous pouch. Post‐operative follow‐up digital subtraction angiography demonstrated no angiographic evidence of residual DAVFs or new haemorrhages.ConclusionDAVFs at the foramen magnum could present as SAH. A combination of neuroimaging methods aid diagnosis and identification of underlying vascular anatomy. Satisfactory outcomes with complete occlusion were achieved with microsurgical approach alone.

A new specimen of pteranodontid pterosaur Bogolubovia orientalis from the upper cretaceous of Penza Province, Russia

ABSTRACT Bogolubovia orientalis, the first pterosaur taxon described from Russia, was known for more than a hundred years from a single specimen, the posterior fragment of the middle cervical vertebra from the Upper Cretaceous (upper Campanian) Rybushka Formation at Malaya Serdoba locality in Penza oblast, Russia. First classified as a pteranodontid, Bogolubovia was long thought to be an azhdarchid, and only very recently has it been again reclassified as a pteranodontid. Here, we describe the second pterosaur vertebra from the Malaya Serdoba locality, an atlantoaxis, which shows distinct pteranodontid characters, such as round cotyle, lack of hypapophysis, rudimentary diapophysis placed anterior to the lateral pneumatic foramen, and pair of posterior lateral pneumatic foramina. The pteranodontid characters of the holotype middle cervical vertebra include high neural arch, which is higher than the centrum and has the postzygapophyses placed well above the condyle, and the large posterior lateral foramina, similar in size with the posterior opening of the neural canal. Both vertebrae can be assigned to the same taxon, Bogolubovia orientalis. Bogolubovia can be distinguished from the pteranodontids Pteranodon and Volgadraco and thus is considered a valid taxon.

Extragonadal germ cell tumor presenting with spinal cord compression: a case report and literature review

BackgroundYolk sac tumor or endodermal sinus tumor is an uncommon malignant germ cell neoplasm. This tumor usually presents in childhood or young adulthood as a testicular or ovarian mass. Extragonadal sites such as mediastinal, intracranial, and sacrococcygeal have been described. A review of the literature revealed limited related cases. The clinical presentation, radiographic characteristics, operative findings, and patient outcomes are discussed.Case presentationWe report the occurrence of a primary paraspinal germ cell tumor in a 28-month-old boy who presented with thoracic spinal cord compression. The patient presented with pain, weakness, paraplegia, and bowel and bladder disturbances.MRI was done and showed a retroperitoneal and paravertebral mass invading the left diaphragmatic crus, the lateral neural foramen, and the posterior paravertebral muscles. Morphologic and immunohistochemical features were consistent with a germ cell tumor, namely an endodermal sinus tumor (yolk sac) of the epidural area. The final diagnosis was determined to be stage IV extragonadal germ cell tumor. The patient underwent emergency surgery consisting of T10–12 laminectomy and epidural mass resection with the release of the spinal cord compression and received chemotherapy consisting of cisplatin, bleomycin, and etoposide. After six cycles of chemotherapy, follow-up MRI showed complete resolution of the tumor. The patient has been in complete remission 16 years from his initial diagnosis. He still, however, has mild residual weakness in both lower extremities and some detrusor-sphincter dyssynergia.ConclusionExtragonadal germ cell tumors presenting with spinal cord compression are rare; however, they should be included in the differential diagnosis of every child younger than 3 years old who does not present with the typical features. Germ cell tumors are sensitive to platinum-based chemotherapy, and surgery should only be performed for spinal cord compression and for obtaining tissue biopsy for a definitive diagnosis. The sooner the decompression is done, the better neurological outcome is achieved. Long-term remission, and possibly cure, can be achieved with a multidisciplinary treatment strategy.

Imaging of Aberrant Internal Carotid Arteries.

Aberrant internal carotid arteries (ICAs) may take abnormal courses in the cervical region. We present the ICA imaging features that suggest the presence of a submucosal mass in the posterior pharyngeal wall caused by such an aberration. Cervical computed tomography angiography images of 2400 patients obtained over 5 years were retrospectively reviewed. The ICA courses at the levels of the hypopharynx and oropharynx were evaluated. Aberrant ICAs running posterior to the pharynx were selected. Vessel location was classified into 3 types: lateral to the vertebral foramen (normal, type I); between the lateral foramen and the uncovertebral joint (type II); and medial to the uncovertebral joint (type III). Medical records were examined, and relationships between symptoms, the ICA variations, and imaging features evaluated. Cervically aberrant ICAs of type II were detected in 45 patients and aberrations of type III in 18. In the latter group, the mean patient age was 66 years, 12 were men and 6 were women. Six (33%) patients (4 men) had clinical symptoms associated with their aberrant ICA courses. In 2 men (11%), both ICAs took aberrant courses. Otherwise, the right ICA was affected in 9 (50%) cases and the left ICA in 7 (39%). Parapharyngeal ICA aberrations were both common and asymptomatic. Such ICAs may be damaged during pharyngeal surgery or intubation. The ICA location should be investigated before any interventional procedure.

Foramen Magnum Dural Arteriovenous Fistula Presenting With Thoracic Myelopathy: Technical Case Report With 2-Dimensional Operative Video

Dural arteriovenous fistulas (dAVFs) are vascular abnormalities of the central nervous system that can cause a wide array of neurological dysfunction depending on their location, flow, and propensity to rupture. Symptomatic dAVFs at the cranio-cervical junction usually result in hemorrhage or cervical myelopathy. Distantly located dAVFs of the foramen magnum are a rare cause of thoracic intrinsic myelopathy. An 83-yr-old man presented with progressive lower extremity weakness, numbness, and difficulty walking along with episodes of bowel incontinence. Magnetic resonance imaging of the cervical spine demonstrated multilevel cervical disc disease with stenosis and longitudinal cervical cord signal change extending into the upper thoracic spinal cord. Cerebral and spinal angiography revealed a dAVF in the lateral foramen magnum region. Given the location, feeding vasculature, and morphology of the fistula, endovascular embolization was not attempted. Microsurgical resection with confirmative indocyanine green fluorescent imaging was performed with adequate obliteration of the fistula. The patient's neurological baseline was preserved postoperatively with improvement of lower extremity numbness. We present a brief overview of this neuropathologic entity and demonstrate microsurgical resection of a foramen magnum dAVF through operative video. Craniocervical dAVFs should remain on the differential diagnosis of patients presenting with progressive thoracolumbar myelopathy.

Effect of Needle Tip Position on Contrast Media Dispersion Pattern in Transforaminal Epidural Injection Using Kambin's Triangle Approach.

PurposeDispersion of contrast media into the anterior epidural space is correlated with better outcomes after transforaminal epidural injection (TFEI). Needle tip position is an important factor affecting the pattern of contrast media dispersion. It is difficult to advance the needle medially to the interpedicle line with a conventional approach, especially in a severe spinal stenosis. But, with Kambin’s triangle approach, the needle can be advanced more medially even in the severe stenosis. We aimed to compare contrast media dispersion patterns according to the needle tip position in TFEI with Kambin’s triangle approach.Patients and MethodsThis single-center retrospective study analyzed fluoroscopic data of patients who underwent TFEI from March 2019 to July 2019. Data on the history of lumbar spinal fusion surgery and MRI findings were collected. The needle tip position was evaluated in three positions on fluoroscopic images (final anteroposterior [AP] view): extraforaminal (EF), lateral foramen (LF), and medial foramen (MF). Contrast media dispersion into the epidural space (epidural pattern) in the AP view was evaluated as a dependent variable. The relationship between the contrast media dispersion pattern and needle tip position was analyzed, and other factors affecting the contrast media dispersion pattern were identified.ResultsNinety-eight TFEI cases were analyzed (51 LF, 35 MF, and 12 EF). An epidural pattern of dispersion was observed more frequently in the LF and MF groups than in the EF group. The LF and MF groups showed no significant difference in epidural pattern frequency. On logistic regression analysis, needle tip position emerged as a major factor influencing epidural pattern, while other factors including spine conditions had no significant effect.ConclusionPositioning the needle tip medial to the pedicle helps in the spread of the contrast media into the epidural space during TFEI with Kambin’s approach. Factors other than the needle tip position did not significantly affect the contrast media dispersion pattern.

A case with multiple accessory foramina of mandible in a fetus

It is aimed to better recognize the mandibular variations by understanding the diversity and positions of accessory foramina better. Accessory formations on a full-term fetal mandible dissected for a mandibular study were examined under a microscope. To observe these formations more clearly, they were photographed with the help of a camera and microscope. In one of the mandibles dissected for a fetal mandibular study, a lateral accessory foramen (LAF1) was detected in the right half just near the mental foramen, and also a medial accessory foramen (MAF1) was detected over the mandibular foramen. In the left half, on the lateral surface relative to the mental foramen, one in the medial (LAF3) and one just above it (LAF2), and last one is near to the ramus of mandible (LAF4), three lateral accessory foramina, were detected. Again, a medial accessory foramen just above the left mandibular foramen (MAF3), and another foramen is near to mandibular symphysis (MAF2), also two medial accessory foramina on the lateral surface were detected. Detection and recognition of such variations are quite important for clinicians in the diagnostic methods and prevention of possible surgical complications.

Microsurgical resection of medullary cavernoma via the olivary zone by the retrosigmoid supracondylar approach.

Microsurgical resection of the medullary cavernoma is rare, comprising less than 15% of more than 250 surgeries of brainstem cavernoma performed by the senior author (H.B.). 1 This video demonstrates a case of a cavernous malformation inside the lateral part of the medulla, which was surgically treated via the olivary zone by the retrosigmoid supracondylar approach in a half-sitting position. Osseous drilling of the lateral foramen magnum provided wide exposure of the cerebellomedullary cistern around the olive. 2,3 The lesion was completely dissected at the appropriate cleavage plane from the normal parenchyma. The patient developed no new neurological deficits and had no recurrence during 3 years of follow-up after the operation.The video can be found here: https://youtu.be/7i7SccS5HmU.

A Micro–computed Tomographic Evaluation of the Accuracy of 3 Electronic Apex Locators in Curved Canals of Mandibular Molars

IntroductionThis study evaluated the accuracy of 3 electronic apex locators (EALs) (CanalPro [Coltene-Endo, Cuyahoga Falls, OH], Apex ID [SybronEndo, Glendora, CA], and Root ZX Mini [J Morita, Tokyo, Japan]) in curved mesial canals of extracted mandibular molars using micro–computed tomographic (micro-CT) scanning. MethodsThe root canal length and the actual working length of 58 canals were measured using the visual method and 3-dimensional micro-CT reconstructions. The measurements of the EALs at marks “APEX/0.0” and “0.5 mark” were recorded as the electronic root canal length and the electronic working length, respectively. The absolute mean values and the percentages of distribution of the electronic measurements were compared with the actual lengths of the canals. The presence of isthmuses, accessory canals, foramen position, and the distance between the apical constriction and the apical foramen were recorded from the micro-CT scans, and their correlation to the accuracy of the EALs was determined. ResultsAll electronic measurements showed high agreement with their respective gold standard, except the electronic root canal length of the Apex ID (P < .05). No difference in the percentage of precise measurements (within the ±0.5 mm) was found among the devices (χ2 and z tests, P > .05). Of the anatomic parameters evaluated, the presence of a lateral foramen negatively affected the 0.0 mark of the Apex ID (Wilcoxon test, P < .05). ConclusionsThe Root ZX Mini and CanalPro were precise for both root canal length and working length determination in mesial curved canals of mandibular molars, whereas the Apex ID was accurate for the working length when using the 0.5 mark.

Dural arteriovenous fistula of the lateral foramen magnum region: A review.

The lateral foramen magnum region is defined as the bilateral occipital area that runs laterally up to the jugular foramen. The critical vasculatures of this region are not completely understood. Dural arteriovenous fistulas that occur in this region are rare and difficult to treat. Therefore, we searched PubMed to identify all relevant previously published English language articles about lateral foramen magnum dural arteriovenous fistulas, and we performed a review of this literature to increase understanding about these fistulas. Four types of dural arteriovenous fistulas occur in the lateral foramen magnum region. These include anterior condylar confluence and anterior condylar vein dural arteriovenous fistulas, posterior condylar canal dural arteriovenous fistulas, marginal sinus dural arteriovenous fistulas, and jugular foramen dural arteriovenous fistulas. These dural arteriovenous fistulas share similar angioarchitectures and clinical characteristics. The clinical presentations of lateral foramen magnum dural arteriovenous fistulas include pulsatile tinnitus, intracranial hemorrhage, myelopathy, orbital symptoms, and cranial nerve palsy. Currently, head computed tomography, computed tomography angiography, magnetic resonance imaging, magnetic resonance angiography and digital subtraction angiography (DSA) are useful for diagnosing dural arteriovenous fistulas, and of these, DSA remains the "gold standard." Most lateral foramen magnum dural arteriovenous fistulas need to be treated due to their aggressive symptoms, and transvenous embolization presents the best options. During treatment, it is critical to accurately place the microcatheter into the fistula point, and intraoperative integrated computed tomography and DSA data are very helpful. Other treatments, such as transarterial embolization, microsurgery or conservative treatment, can also be chosen. After appropriate treatment, most patients with lateral foramen magnum dural arteriovenous fistulas achieve satisfactory outcomes.

Anatomical Description of Zygomatic Foramina in African American Skulls.

The zygomaticofacial/temporal/orbital nerve is a terminal branch of the zygomatic nerve and exits the orbit through zygomatic foramina. The nomenclature in the literature varies with some studies identifying all 3 foramina on the malar surface of the zygoma, while others describe each along different aspects of the zygoma. In this study, foramen on the malar surface of the zygoma is termed zygomatic foramen, and the authors describe anatomical variations in the position and number of these foramina in an African American population. Sixty-two African American skulls from the Hamann-Todd collection of the Cleveland Museum of Natural History were studied. The primary outcome was the number of zygomatic foramina on the malar surface of the zygomatic bone. Secondary outcomes included the location of foramina relative to the orbital rim and the frontozygomatic suture. Mean and standard deviation were used to describe measurements. Chi-squared and Wilcoxon signed rank tests were used to analyze measurements between left and right hemicrania. The average number of foramina was 1.98 ± 0.93. More foramina were found on the right (2.13 ± 0.98) when compared with the left (1.68 ± 0.79; p = 0.001). The average distance between the lateral-most and medial-most foramina was 9.7 ± 5.0 mm. The distance from the orbital rim to the lateral foramen was 8.4 ± 4.2 mm, and distance from the orbital rim to the medial foramen was 7.7 ± 2.1 mm. The frontozygomatic suture was 22.9 ± 3.9 mm from the lateral foramen and 27.9 ± 3.6 mm from the medial foramen. The locations of the foramina in relation to the frontozygomatic suture and orbital rim were consistent with other populations. However, in this African American population, more zygomatic foramina were noted compared with previously published results in Korean, Indian, Brazilian, and West Anatolian populations. Surgeons should be cognizant of zygomatic foramina in this population to reduce potential neurovascular complications.

The Relationship amongst Intervertebral Disc Vertical Diameter, Lateral Foramen Diameter and Nerve Root Impingement in Lumbar Vertebra

Introduction: The vertical diameter of the foramen is dependent upon the vertical diameter of the corresponding intervertebral disc. A decrease in disc vertical diameter has direct anatomic consequences to the foraminal diameter and area available for the nerve root passing through it. This study is to establish the relationship amongst the intervertebral disc vertical diameter, lateral foramen diameters and nerve root compression in the lumbar vertebra.Materials and Methods: Measurements of the study parameters were performed using sagittal MRI images. The parameters studied were: intervertebral disc vertical diameter (DVD), foraminal vertical diameter (FVD), foraminal transverse diameter (FTD) and nerve root diameter (NRD) of both sides. The relationship between the measured parameters were then analyzed.Results: A total of 62 MRI images were available for this study. Statistical analysis showed moderate to strong correlation between DVD and FVD at all the lumbar levels except at left L23 and L5S1 and right L3L4 and L4L5. Correlation between DVD and FTD were not significant at all lumbar levels. Regression analysis showed that a decrease of 1mm of DVD was associated with 1.3, 1.7, 3.3, 3.3 and 1.3mm reduction of FVD at L1L2, L2L3, L3L4, L4L5 and L5S1 respectively.Conclusion: Reduction of DVD was associated with reduction of FVD. However, FVD was relatively wide for the nerve root even with complete loss of DVD. FTD was much narrower than the FVD making it more likely to cause nerve root compression at the exit foramina. These anatomical details should be given consideration in treating patients with lateral canal stenosis.

A New Genus of the Corythoecidae (Paleozoic Radiolaria) from the Changhsingian (Uppermost Permian) Dalong Formation in Southern Guizhou, South China

Abstract. A new genus of the Corythoecidae (Albaillellaria, Radiolaria) was recovered from the Changhsingian (uppermost Permian) Dalong Formation in Guizhou Province, South China. Qiania Ito and Feng, gen. nov., containing Q. foremanae Ito and Feng, gen. et sp. nov. and Q. uncinata (Rudenko and Panasenko), is characterized by a conical shell consisting of an apical portion and an inflated region with a lateral foramen on the ventral side. The Corythoecidae were thought to range from the Late Devonian to Guadalupian (middle Permian). Therefore, this new find suggests the presence of this family until the latest Permian. Compilation of previous occurrences of corythoecids, in addition to those of Qiania, showed that most corythoecids including Qiania occurred in phosphate-rich facies, and that Qiania occurred in deeper facies than other corythoecids.

Gross anatomical syringeal structures of goose (Anser anser domesticus)

Objective: The main purpose of this study was to give detailed information on the position and normal anatomical syringeal structure in goose which had received a little attention in the field of veterinary anatomy. Materials and methods: Six (3 females and 3 males) adult geese weighing 2-4 Kg were used. The goose was slaughtered and its body cavity was opened to detect in situ position of the syrinx. Then the syrinx were dissected and fixed in 10% formaldehyde for 48 h and then kept in 70% ethanol for 2 h. Results: Anatomical examination showed that the syringes of these birds were located in the thoracic cavity at the bifurcation of the trachea. The syrinx was tracheobronchial type formed by tracheosyringeal cartilages, bronchosyringeal cartilages, pessulus, medial and lateral tympaniform membranes, interbronchial ligament and foramen as well as extrinsic syringeal muscles. Conclusion: There were some similarities and some differences of the anatomical structures of the syrinx of goose and that of other bird species. No differences between male and female syrinx were observed.

Posterior condylar canals and posterior condylar emissary veins—a microsurgical and CT anatomical study

The posterior condylar canals (PCCs) and posterior condylar emissary veins (PCEVs) are potential anatomical landmarks for surgical approaches through the lateral foramen magnum. We conducted computed tomography (CT) and microsurgical investigation of how PCCs and PCEVs can aid in planning and performing these approaches. We analyzed the microanatomy of PCCs and PCEVs using cadaveric specimens, dry skulls, and CT images. The recognition frequency and geometry of PCCs and PCEVs and their relationships with surrounding structures were evaluated. PCCs were identified in 36 of 50 sides in dry bones and 82 of 100 sides by CT. PCCs had a 3.5-mm mean diameter and a 6.8-mm mean canal length. We classified their courses into four types according to intracranial openings: the sigmoid sinus (SS) type, the jugular bulb (JB) type, the occipital sinus type, and the anterior condylar emissary vein type. In most cases, PCEV originated near the boundary between the SS and JB. PCCs and PCEVs can be useful anatomical landmarks to differentiate the transcondylar fossa approach from the transcondylar approach, thus preventing unnecessary injury of the atlantooccipital joint. They can also be used as landmarks when the jugular foramen (JF) and hypoglossal canal (HGC) are being exposed. The area anterior to the brain stem and the medial part of HGC can be accessed by removal of the lateral foramen magnum medial to PCC. JF and the lateral part of HGC can be accessed by removal of the skull base lateral to PCC without damaging the lateral rim of the foramen magnum.

INSIGHT ON THE THEROPOD FAUNA FROM THE UBERABA FORMATION (BAURU GROUP), MINAS GERAIS STATE: NEW MEGARAPTORAN SPECIMEN FROM THE LATE CRETACEOUS OF BRAZIL

The first bony theropod record from the Campanian Uberaba Formation (Bauru Group) is described. It consists of an isolated caudal centrum (CPPLIP 1324) found in the city of Uberaba, Minas Gerais State, Brazil. The amphicoelous centrum possesses a length to height ratio of 1.74, deep elliptical lateral pneumatic foramen representing 26% of centrum length with three main sub-circular air chambers, andcamellate internal structure.This combination of features is shared with Aerosteon , Megaraptor , and Orkoraptor from the Late Cretaceous of Argentinaand with the Megaraptora indet. fromthe Sao Jose do Rio Preto Formation (Bauru Group), Sao Paulo State,allowing us to refer it to the Megaraptora clade (Tetanurae, Neovenatoridae). As such, the new specimen represents the second megaraptoran from the Late Cretaceous of Brazil and provides new information on tail anatomy on this bizarre group.

Reinvestigation of the basicranium of Haldanodon exspectatus (Mammaliaformes, Docodonta)

ABSTRACT The docodont Haldanodon exspectatus, a mammaliaform from the Late Jurassic of Portugal, is a crucial taxon for studying higher-level relationships of mammaliaforms and their morphological evolution. Based on high-resolution computed tomography scanning of three specimens of Haldanodon, we developed a new reconstruction of the basicranium including the petrosal and the inner ear. Our study confirms that Haldanodon and other basal mammaliaforms, such as Morganucodon and Sinoconodon, are similar in the main characteristics of their external anatomy of the petrosal. However, Haldanodon shows several derived features that support a phylogenetic position of docodonts more derived than Morganucodon and Sinoconodon: (1) elongated and curved cochlear canal (nearly 180°), (2) single lateral flange foramen of petrosal, (3) absence of anterior paroccipital process, and (4) squamosal constriction. The bony labyrinth reveals a secondary crus commune, which is regarded to be a plesiomorphic feature of the mammaliaform groundplan. The cochlear canal shows an apical inflation connected to a distinct sulcus and a separate notch in the internal acoustic meatus, supporting the existence of a lagenar nerve and macula as in monotremes. Haldanodon is unique among Mesozoic mammaliaforms in having a hypertrophied paroccipital region that is excavated into large tympanic pneumatic recesses, which are connected with the extensive porous and probably also pneumatic internal structures of the surrounding bones. The curved cochlear canal and the pneumatized middle ear region support the hypothesis that Haldanodon had more effective low-frequency hearing as an adaptation to a fossorial mode of life.

Ultrasound-Guided Cervical Periradicular Steroid Injection for Cervical Radicular Pain: Relevance of Spread Pattern and Degree of Penetration of Contrast Medium

Ultrasound-guided cervical periradicular steroid injection (US-CPSI) is an attractive alternate to conventional C-arm guided transforaminal epidural injection for treatment of cervical radicular pain. We compared the technical differences and clinical outcomes between these two techniques. Following ultrasound-guided needle placement, the extent of contrast media spread and the degree of tissue penetration were monitored by real-time fluoroscopy at the time of cervical periradicular injection in 59 patients. The spread pattern was judged to be medial foramen (medial bisector of foramen), lateral foramen (lateral bisector of foramen), or extraforaminal. The degree of tissue penetration was classified into periradicular, pararadicular, and intramuscular based on the penetration characteristics. Ultrasonographic images were categorized into crescent, perineuronal protruding, and intramuscular types. These groups were then correlated with clinical outcomes. The actual distance between the ultrasound-guided needle position and fluoroscopic target point was 1.9 and 2.3 cm in the oblique and anteroposterior view, respectively. Despite a difference in ultrasound and fluoroscopic end points, contrast dye spread was found to reach lateral foramen in 53%, medial foramen in 34%, and extraforaminal in 13% of the subjects. Analysis of postprocedural pain reduction (PPPR) showed significantly the better outcomes in periradicular and pararadicular penetration, medial and lateral, and crescent and perineural protruding type without subgroup differences than intramuscular penetration, extraforaminal spread, and ultrasonographic images of intramuscular type (P < 0.001). Analysis of clinical overall outcome showed favorable outcome in the groups with better results of PPPR. Our preliminary data suggest that the technique of UP-CPSI can provide an adequate local spread pattern, tissue penetration for treatment of cervical radicular pain.