Foramen Magnum Research Articles

Anaesthetic management of a child with syringomyelia undergoing foramen magnum decompression: A case report

Anaesthetic management of a child with syringomyelia undergoing foramen magnum decompression: A case report

Anatomical Characteristics of Cervicomedullary Compression on MRI Scans in Children with Achondroplasia

This retrospective study assessed anatomical characteristics of cervicomedullary compression in children with achondroplasia. Twelve anatomical parameters were analyzed (foramen magnum diameter and area; myelon area; clivus length; tentorium and occipital angles; brainstem volume outside the posterior fossa; and posterior fossa, cerebellum, supratentorial ventricular system, intracranial cerebrospinal fluid, and fourth ventricle volumes) from sagittal and transversal T1- and T2-weighted magnetic resonance imaging (MRI) scans from 37 children with achondroplasia aged ≤ 4 years (median [range] 0.8 [0.1–3.6] years) and compared with scans from 37 children without achondroplasia (median age 1.5 [0–3.9] years). Mann–Whitney U testing was used for between-group comparisons. Foramen magnum diameter and area were significantly smaller in children with achondroplasia compared with the reference group (mean 10.0 vs. 16.1 mm [p < 0.001] and 109.0 vs. 160.8 mm2 [p = 0.005], respectively). The tentorial angle was also steeper in children with achondroplasia (mean 47.6 vs. 38.1 degrees; p < 0.001), while the clivus was significantly shorter (mean 23.5 vs. 30.3 mm; p < 0.001). Significant differences were also observed in myelon area, occipital angle, fourth ventricle, intracranial cerebrospinal fluid and supratentorial ventricular volumes, and the volume of brainstem protruding beyond the posterior fossa (all p < 0.05). MRI analysis of brain structures may provide a standardized value to indicate decompression surgery in children with achondroplasia.

Stem Cells Treatment for Subarachnoid Hemorrhage.

Subarachnoid hemorrhage (SAH) refers to bleeding in the subarachnoid space, which is a serious neurologic emergency. However, the treatment effects of SAH are limited. In recent years, stem cell (SC) therapy has gradually become a very promising therapeutic method and advanced scientific research area for SAH. The SCs used for SAH treatment are mainly bone marrow mesenchymal stem cells (BMSCs), umbilical cord mesenchymal stem cells (hUC-MSCs), dental pulp stem cells (DPSCs), neural stem cells (NSCs)/neural progenitor cell (NPC), and endothelial progenitor cell (EPC). The mechanisms mainly included differentiation and migration of SCs for tissue repair; alleviating neuronal apoptosis; anti-inflammatory effects; and blood-brain barrier (BBB) protection. The dosage of SCs was generally 106 orders of magnitude. The administration methods included intravenous injection, nasal, occipital foramen magnum, and intraventricular administration. The administration time is generally 1 hour after SAH modeling, but it may be as late as 24 hours or 6 days. Existing studies have confirmed the neuroprotective effect of SCs in the treatment of SAH. SC has great potential application value in SAH treatment, a few case reports have provided support for this. However, the relevant research is still insufficient and there is still a lack of clinical research on the SC treatment for SAH to further evaluate the effectiveness and safety before it can go from experiment to clinical application.

Symptomatic Multi-Nodular Fourth Ventricular Choroid Plexus Papillary Fibrosis in the Context of Chiari II Malformation: Case Report and Literature Review

Introduction: Chiari II malformation (CM-II) is a congenital malformation characterized by the caudal displacement of the cerebellar tonsils, inferior cerebellar vermis, and fourth ventricle through the foramen magnum. Although rare, the association between CM-II and the development of a variety of mass lesions within the fourth ventricle and craniocervical junction has been described in the literature. Case Presentation: We present the case of a 9-year-old boy with a history of mid-lumbar myelomeningocele, CM-II, and ventriculoperitoneal shunt-dependent hydrocephalus who was discovered to have a syringomyelia and numerous spherical/ovoid masses within the caudal fourth ventricle and dorsal cervicomedullary subarachnoid space on a surveillance brain MRI. On questioning, the patient endorsed a longstanding history of poor bilateral hand dexterity and grip strength. After further imaging workup, the patient underwent suboccipital craniectomy and C1 laminectomy for resection of the mass lesions arising from the fourth ventricular choroid plexus (CP) and performance of an expansile pericranial duraplasty. The patient tolerated surgery well and had progressive improvement in hand dexterity/strength as well as radiographic improvement in the cervical cord syrinx after surgery. Pathologic analysis of the resected mass lesions demonstrated the lesions to be predominantly characterized by dense nodular fibrosis of the CP stromal cores which we are describing as choroid plexus papillary fibrosis. A minority of the lesional stromal cores were noted to be edematous, imparting a more “reticular” appearance. There were no features to suggest a neoplastic or infectious process. Conclusion: This combination of dysplastic/reactive CP histologic findings has not been previously reported in an extramedullary location. The unique pathology of this patient’s CP lesions will be discussed, and previously reported fourth ventricular mass lesions seen in association with CM-II will be reviewed.

Dural arteriovenous fistulas at the craniocervical junction: a systematic review and meta-analysis.

The management for craniocervical junction dural arteriovenous fistulas (CCJ-DAVFs) remains controversial and clinically challenging. We systemically summarized the clinical and angiographic outcomes of microsurgery, embolization, and conservative management. Relevant articles were retrieved from PubMed, Scopus, Web of Science, and Cochrane, following PRISMA guidelines. A systematic review and meta-analysis were conducted on the clinical characteristics, management approaches, and clinical and angiographic outcomes. We included 13 articles (166 patients). The weighted mean age was 58.9 years (95%CI: 53.2-64.5), 58.8 years (95%CI: 48.4-69.2), and 63.8 years (95%CI: 60.1-67.5), in microsurgery, embolization, and conservative groups respectively, with an overall male sex predominance (microsurgery [n = 51/77, 66.2%], embolization [n = 44/56, 78.6%], and conservative management [n = 6/8, 75.0%]). Patients were managed with microsurgery (n = 80/172, 46.5%), embolization (n = 79/172, 45.9%), and conservative treatment (n = 13/172, 7.6%). Foramen magnum was the most common location (microsurgery [n = 34/77, 44.2%], embolization [n = 31/56, 55.4%], and conservative treatment [n = 3/8, 37.5%]). Vertebral artery was the primary feeder (microsurgery [n = 58/84, 69.1%], embolization [n = 41/86, 47.6%], and conservative treatment [n = 4/7, 57.1%]). Complete fistula obliteration rates were 74.1% (95%CI:52.3-88.2%) in the microsurgery group and 54.9% (95%CI:30.7-77.0%) in the embolization group. Complications rates were 16.2% (95%CI:6.7-34.5%) in the embolization group, 11.6% (95%CI:3.8-30.4%) in the microsurgery group, and 7.7% (95%CI:1.1-39.1%) in the conservative group. Different rates of good clinical outcomes were observed [microsurgery: 66.4% (95%CI:48.1-80.8%), embolization: 51.9% (95%CI:30.8-72.4%), and conservative: 11.6% (95%CI:4.4-27.4%)]. In patients with CCJ-DAVFs, each management approach has its own merits based on the fistula and patient characteristics.

A Prospective Study of CSF Flow Dynamics Across Foramen Magnum in Adult Chiari Malformation/Syringomyelia Complex and its Clinical Correlation with Outcomes after Surgery

Abstract Introduction Chiari I malformation refers to cerebellar tonsillar descent below the foramen magnum and is frequently associated with syringomyelia. Prior cerebrospinal fluid (CSF) flow studies correlated the clinical severity of these lesions with general flow velocity or bulk flow at the foramen magnum; however, these techniques have not assessed the effect on surgical outcomes. The study aims to present clinical and radiological factors and CSF flow parameters (pre- and postoperative) that affect the surgical outcome. Materials and Methods The institutional ethics committee approved the study. We collected the prospective clinical data, including pre- and postoperative symptoms. Functional grades were determined along with the change in clinical improvement based on clinical examination notes, the change in functional grade was calculated, and the radiologic data were analyzed according to the degree of clinical improvement. The surgical procedure included suboccipital bony decompression with duroplasty. Patients were followed up at 1 month, 3 months, and 1 year. Results There were a total of 25 patients. The mean age of the patients was 45.52 ± 13.37 years, with 40% being males and 60% being females. After the surgery, there was a significant increase in the anterior and posterior CSF flows at the foramen magnum. Most had a resolution in the headache and sensory symptoms, while the lower cranial nerve and motor symptoms had a minor resolution at follow-up. Age, sex, and headache do not correlate with the outcome or syrinx improvement. Motor power in the lower limb (preintervention) and syrinx shape (preintervention) were significantly associated with the variable “anterior flow at the foramen magnum” (preintervention; p < 0.05). Average flow, cervicomedullary angle (postintervention), sensory symptom progression, and CSF flow change anterior to the foramen magnum were significantly associated with the variable “anterior flow at the foramen magnum” (postintervention; p < 0.05). Conclusion Even after surgery, persistent foramen magnum CSF outflow obstruction has a robust negative correlation with the outcome. The Chiari outcome predictability index has shown a significant correlation with patient outcomes and can be used to inform patients about the expected outcome. The results of the present study will be helpful in stratifying patients according to their desired outcomes.

Stress Maneuver for Basilar Invagination Reduction: A Technical Report

BackgroundBasilar invagination (BI) is a prolapse of the odontoid process cranially and posteriorly towards the foramen magnum. Several surgical treatment options are available for this condition. Herein, we describe a stress maneuver technique for BI reduction using a single-stage posterior approach. MethodsWe described the case of a 56-year-old male diagnosed with type A BI and brainstem compression, who was treated with posterior fossa decompression and occipitocervical fusion. The BI was reduced intraoperatively using a stress maneuver, and cranial traction or atlantoaxial joint distraction was not necessary. ResultsPostoperative imaging revealed a reduction of the odontoid process and adequate brainstem decompression. The patient showed progressive improvement of his symptoms. ConclusionIn selected cases, stress maneuvers for BI reduction can be a less morbid, easier, and replicable option within the already existing technical arsenal.

Morphological observation of occipital condyle position in Chinese skulls and potential clinical significance.

To study the anatomy of the Chinese occipital condyle and its position relative to the occipital foramen and skull. Measurements were taken from 106 adult Chinese skulls using a Cartesian coordinate system centered on the foramen magnum. Measurements included the longitudinal diameter of the foramen magnum, distances from various points on the occipital condyles to the foramen magnum and skull landmarks, and the occipital condyle classification index (OCI) and skull-occipital condyle classification index (SOCI). OCI categorized the position of the foramen magnum and occipital condyles into three groups: OCI ≤ 0.40 (3 cases, 2.83%), 0.40 < OCI ≤ 0.50 (75 cases, 70.75%), and OCI > 0.50 (28 cases, 26.42%). SOCI categorized the relationship between the skull and occipital condyles into two groups: 0.5 < SOCI ≤ 0.6 (49 cases, 46.23%) and 0.6 < SOCI ≤ 0.7 (57 cases, 53.77%). Four relationship types were identified based on specific measurements: Type I (23 cases, 21.70%), Type II (42 cases, 39.62%), Type III (4 cases, 3.77%), and Type IV (37 cases, 34.91%). Sagittal movement of the occipital condyle affects the cervical spine's curvature. Asymmetry between the occipital condyles and the foramen magnum may misalign the skull with the body's coronal plane.

A Rare Case of Tumor-Induced Osteomalacia Due to Mesenchymal Tumor at Foramen Magnum Diagnosed Preoperatively on 68Ga DOTATATE PET/CT.

A 42-year-old man, a known case of FGF23-dependent hypophosphatemia, underwent 68Ga- DOTATATE PET-CT, which showed a somatostatin receptor-expressing lesion in the left arch of foramen magnum that was correlated on MRI as a soft tissue lesion measuring 2.2 × 1.3 cm. It was excised and histopathologically confirmed as phosphaturic mesenchymal tumor. Postoperatively, patient improved clinically and recovered from hypophosphatemia completely. A distinct focal uptake in a 68Ga- DOTATATE PET-CT in a patient with tumor-induced osteomalacia needs extensive workup and high degree of suspicion to rule out mesenchymal tumor at nonconventional location as seen in the present case.

Achondroplasia: aligning mouse model with human clinical studies shows crucial importance of immediate postnatal start of the therapy.

Achondroplasia is the most common form of human dwarfism caused by mutations in the FGFR3 receptor tyrosine kinase. Current therapy begins at two years of age and improves longitudinal growth but does not address the cranial malformations including midface hypoplasia and foramen magnum stenosis, which lead to significant otolaryngeal and neurologic compromise. A recent clinical trial found partial restoration of cranial defects with therapy starting at 3months of age, but results are still inconclusive. The benefits of achondroplasia therapy are therefore controversial, increasing skepticism among the medical community and patients. We used a mouse model of achondroplasia to test treatment protocols aligned with human studies. Early postnatal treatment (from day 1) was compared to late postnatal treatment (from day 4, equivalent to ~5months in humans). Animals were treated with the FGFR3 inhibitor infigratinib and the effect on skeleton was thoroughly examined. We show that premature fusion of the skull base synchondroses occurs immediately after birth and leads to defective cranial development and foramen magnum stenosis in the mouse model to achondroplasia. This phenotype appears significantly restored by early infigratinib administration when compared to late treatment, which provides weak to no rescue. In contrast, the long bone growth is similarly improved by both early and late protocols. We provide clear evidence that immediate postnatal therapy is critical for normalization of skeletal growth in both the cranial base and long bones and the prevention of sequelae associated with achondroplasia. We also describe the limitations of early postnatal therapy, providing a paradigm-shifting argument for the development of prenatal therapy for achondroplasia.

The Genetics of Chiari 1 Malformation.

Chiari malformation type 1 (CM1) is a structural defect that involves the herniation of the cerebellar tonsils through the foramen magnum, causing mild to severe neurological symptoms. Little is known about the molecular and developmental mechanisms leading to its pathogenesis, prompting current efforts to elucidate genetic drivers. Inherited genetic disorders are reported in 2-3% of CM1 patients; however, CM1, including familial forms, is predominantly non-syndromic. Recent work has focused on identifying CM1-asscoiated variants through the study of both familial cases and de novo mutations using exome sequencing. This article aims to review the current understanding of the genetics of CM1. We discuss three broad classes of CM1 based on anatomy and link them with genetic lesions, including posterior fossa-linked, macrocephaly-linked, and connective tissue disorder-linked CM1. Although the genetics of CM1 are only beginning to be understood, we anticipate that additional studies with diverse patient populations, tissue types, and profiling technologies will reveal new insights in the coming years.

Morphometric study of foramen magnum and its correlation with cranial morphometry in dry human skulls of north India

Morphometric study of foramen magnum and its correlation with cranial morphometry in dry human skulls of north India

Classification, angioarchitecture and treatment outcomes of medullary bridging vein-draining dural arteriovenous fistulas in the foramen magnum region: a multicenter study.

This study aimed to classify medullary bridging vein-draining dural arteriovenous fistulas (MBV-DAVFs) located around the foramen magnum (FM) according to their location and characterize their angioarchitecture and treatment outcomes. Patients with MBV-DAVFs diagnosed between January 2013 and October 2022 were included. MBV-DAVFs were classified into four groups. Jugular vein-bridging vein (JV-BV) DAVF: located in proximity to jugular fossa, Anterior condylar vein (ACV)-BV DAVF: proximity to anterior condylar canal, Marginal sinus (MS)-BV DAVF: lateral surface of FM and Suboccipital cavernous sinus (SCS)-BV DAVF: proximity to dural penetration of vertebral artery. Twenty patients were included, three JV-BV, four ACV-BV, three MS-BV and ten SCS-BV DAVFs, respectively. All groups showed male predominance. There were significant differences in main feeders between JV (jugular branch of ascending pharyngeal artery) and SCS group (C1 dural branch). Pial feeders from anterior spinal artery (ASA) or lateral spinal artery (LSA) were visualized in four SCS and one MS group. Drainage pattern did not differ between groups. Transarterial embolization (TAE) was performed in three, two, one and two cases and complete obliteration was obtained in 100%, 50%, 100% and 0% in JV, ACS, MS and SCS group, respectively. Successful interventions without major complications were finally obtained in 100%, 75%, 100%, and 40% in JV, ACS, MS and SCS group, respectively. JV-BV DAVFs were successfully treated using TAE alone. SCS-BV DAVFs were mainly fed by small C1 dural branches of vertebral artery often with pial feeders from ASA or LSA, and difficultly treated by TAE alone.

Morphological and Morphometric Analysis of Carotid Canal Apertures in the Nigerian Population

Background: The external opening of the carotid canal (EOCC), the entry point of the internal carotid artery into the skull, varies across populations. This study characterized the EOCC with the mastoid process (shortest distance from the EOCC to the tip of the mastoid process [SDTCC]), the foramen magnum (shortest distance from the EOCC to the foramen magnum [SDFM]), and the midline of the skull base (shortest distance from the EOCC to the midline of the base of the skull [SDMCC]) in the Nigerian population. Materials and Methods: Fifty skull base pictures were taken in the plumed position with a digital camera. Measurements were taken using Image J software, and Euclidean distances were calculated. The shapes of the EOCC were noted. Paleontological Statistics (PAST 3.0) was used to perform descriptive statistics. Paired ttest and Pearson correlation were used to compare bilateral values and the relationship between the parameters, respectively. Results: The length (right, 0.53 [standard deviation (SD)=2.5] mm; left, 10.99 [SD=2.84] mm) and width (right, 13.96 [SD=2.43] mm; left, 14.16 [SD=2.09] mm) of the EOCC were recorded. In contrast to the populations in South Africa, Serbia, and India, the length of the EOCC obtained from this study is shorter than the breadth. The length of SDFM (right, 41.04 mm; left, 44.13 mm), SDMCC (right, 58.4 mm; left, 57.97 mm), and SDTCC (right, 57.29 mm; left, 55.61 mm) was established among Nigerians. Conclusion: The Nigerian population showed EOCC of shorter length than the breadth compared to other populations, and the size of the skull is independent of the foramina size. These dimensions may provide information for procedures that affect the skull base.

The effect of midline shift on survival time in dogs with structural brain disease diagnosed on MRI.

The effect of midline shift identified on brain MRI on survival time in dogs with structural brain disease is relatively unknown. This retrospective single-centered cohort study reviewed medical and imaging data of 77 dogs with structural brain lesions evident on MRI. Images were reviewed for the presence of midline shift, brain edema, foramen magnum herniation, and ventriculomegaly. Kaplan-Meier method and Cox regression analysis were undertaken to compare survival between dogs with and without midline shift. Midline shift was present in 40 of 77 (52%) dogs and absent in 37 of 77 (48%). Univariate analysis revealed that dogs with midline shift had a median survival time of 34.5 days (95% CI, 4-108 days) compared with 241 days (95% CI, 133,- days) in dogs without midline shift (hazard ratio=2.67, 95% CI, 1.5-4.49). Multivariate Cox regression analysis revealed a hazard ratio of 3.6 (95% CI, 1.7-7.6; P-value<.001) for dogs with midline shift. Shorter median survival times remained significant in all groups after segregation based on etiological diagnosis. The significantly shorter survival times observed herein for dogs with midline shifts, regardless of etiologic cause, provide further evidence that midline shift holds value as a negative prognostic factor in diagnostic imaging.

Posterior fossa decompression in patients with Chiari malformation type 1: effect on sleep apnea and follow-up outcomes.

Sleep apnea, posing significant health risks, is frequently associated with Chiari malformation (CM), characterized by cerebellar tonsil herniation through the foramen magnum. Central sleep apnea (CSA) in CM results from impaired brain-to-muscle signaling and requires treatment. Conversely, obstructive sleep apnea (OSA), arising from throat muscle relaxation, typically unrelated to CM, often coexists. This study evaluates the effectiveness of posterior fossa decompression (PFD) on sleep apnea. A retrospective chart review was conducted of pediatric patients with CM-1 and sleep apnea who underwent PFD between April 1, 2004, and September 30, 2022. Data collected included demographics, clinical characteristics, adenotonsillectomy status, PFD details, and sleep study parameters like the apnea-hypopnea index and respiratory disturbance index. Statistical analysis assessed the surgery's impact on sleep apnea severity. The study included eleven patients, predominantly male (63.6%). All had OSA (100%), with 63.6% also having CSA. Preoperative sleep studies classified OSA severity as 36.4% mild, 18.2% moderate, and 45.5% severe, with no change post-surgery. CSA severity initially included seven mild cases, which became three mild, one moderate, and three resolved cases post-surgery. Among seven patients who had adenotonsillectomy before decompression, five showed no improvement in OSA severity post-surgery. This study elucidates the complex relationship between CM-1, sleep apnea, and PFD. The findings show the persistence of sleep apnea in some patients and highlight the need for continuous monitoring of these patients in order to optimize their care after surgery.

Precise Localization of the Posterior Clinoid Process in the Fetal Skull Base.

To determine the precise position of the posterior clinoid process (PCP) in fetuses. Skull bases of 32 fetuses (11 males/21 females) aged 17 to 32 weeks in utero were included in the study. The distances of PCP to certain reference points were measured. The distances of PCP to the foramen ovale, foramen rotundum, superior orbital fissure, anterior clinoid process, foramen magnum, and crista galli were measured as 7.70±1.86mm, 6.99±1.65mm, 6.07±1.85mm, 3.85±1.10mm, 15.34±3.38mm, and 14.49±2.65mm, respectively. All parameters were similar for both sides (P>0.05). Apart from the distance of PCP to the foramen magnum, the remaining parameters were similar for both genders. This parameter was greater in males than females (P=0.001). All parameters were greater in the third-trimester fetuses than the second-trimester fetuses. All parameters increased with advancing gestational weeks (P<0.001). Linear functions were calculated for the distances of PCP to the crista galli (y = 1.311 + 0.551 × age), to the foramen magnum (y = 0.086 + 0.638 × age), to the anterior clinoid process (y = -0.303 + 0.174 × age), to the superior orbital fissure (y = - 2.013 + 0.338 × age), to the foramen rotundum (y = 1.803 + 0.217 × age), and to the foramen ovale (y = 0.760 + 0.290 × age). The measured distances increased with growth. The linear functions displaying the growth dynamics of PCP-related parameters may be used to estimate the distances.

MNGA-06 MANAGEMENT OF FORAMEN MAGNUM TUMORS, EXPERIENCE OF THE SERVICE OF THE ARRAZI HOSPITAL OF THE CHU MOHAMMED VI OF MARRAKECH

Abstract Tumors of the foramen magnum (FM) are intra or extradural expansive processes located in a region, very complex anatomically, limited, according to George and Al. Meningiomas and neuromas are the main tumors encountered intradurally, while extradural ones are mainly represented by chordomas and bone tumors. The objective of this work was to study the radio-clinical and anatomopathological characteristics, the place of surgery in the therapeutic management, as well as the prognostic factors of this pathological entity through a series of 10 cases collected at the service of Neurosurgery of the Mohamed VI of Marrakech, with literature review. The FM, unusual seat of expansive processes, gives passage to several vital anatomical structures which make the gravity and the particularity of this pathological entity. The preposterous clinical symptomatology, where no sign is pathognomonic, can simulate several other neurological disorders. MRI is the most useful and least invasive examination for the diagnosis and management of foramen magnum tumors. The optimal therapeutic option is total excision of the tumour. However, given the location, nature and tumor volume as well as the involvement of the vertebral artery, the surgical procedure may be limited to subtotal excision. Several surgical approaches have been described to increase efficiency and minimize operative morbidity. A midline posterior approach combined with microsurgical techniques yields good results. Postoperative complications can be dramatic and should be anticipated. The histological spectrum essentially includes meningiomas and neuromas. The prognosis largely depends on the early diagnosis and treatment, the preoperative neurological state, the location and extent of tumor excision, as well as the quality of care provided postoperatively.

Sex estimation by morphometric analysis of the intracranial volume and foramen magnum on three-dimensional volume rendering computed tomography

Purpose: Identification of decomposed human bodies and bone remains is very important in medicolegal examinations. The cranium has an important place in sex estimation due to its dimorphic features. Recent studies in this field have used radiological methods. The present study aimed to examine sexual dimorphism through morphometric analysis of the intracranial volume and Foramen Magnum on Three-Dimensional (3D) Volume Rendering Computed Tomography (CT) images. Methods: For this purpose, 3D images were generated after the reconstruction of CT Angiography scans of 87 female and 107 male cases. The length, width, circumference, area, and intracranial volume of the foramen magnum were measured on these 3D images. Results: All measurements except foramen magnum index were greater in males than in females (p

Gender Determination with foramen magnum using Computed Tomography scans

Gender Determination with foramen magnum using Computed Tomography scans