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Neurosurgical Review Apr 2024Segmentation tools continue to advance, evolving from manual contouring to deep learning. Researchers have utilized segmentation to study a myriad of posterior...
BACKGROUND
Segmentation tools continue to advance, evolving from manual contouring to deep learning. Researchers have utilized segmentation to study a myriad of posterior fossa-related conditions, such as Chiari malformation, trigeminal neuralgia, post-operative pediatric cerebellar mutism syndrome, and Crouzon syndrome. Herein, we present a summary of the current literature on segmentation of the posterior fossa. The review highlights the various segmentation techniques, and their respective strengths and weaknesses, employed along with objectives and outcomes of the various studies reported in the literature.
METHODS
A literature search was conducted in PubMed, Embase, Cochrane, and Web of Science up to November 2023 for articles on segmentation techniques of posterior fossa. The two senior authors searched through databases based on the keywords of the article separately and then enrolled joint articles that met the inclusion and exclusion criteria.
RESULTS
The initial search identified 2205 articles. After applying inclusion and exclusion criteria, 77 articles were selected for full-text review after screening of titles/abstracts. 52 articles were ultimately included in the review. Segmentation techniques included manual, semi-automated, and fully automated (atlas-based, convolutional neural networks). The most common pathology investigated was Chiari malformation.
CONCLUSIONS
Various forms of segmentation techniques have been used to assess posterior fossa volumes/pathologies and each has its advantages and disadvantages. We discuss these nuances and summarize the current state of literature in the context of posterior fossa-associated pathologies.
Topics: Humans; Arnold-Chiari Malformation; Cranial Fossa, Posterior; Magnetic Resonance Imaging
PubMed: 38637466
DOI: 10.1007/s10143-024-02366-4 -
Advances and Technical Standards in... 2024The diagnosis of Chiari I malformation is straightforward in patients with typical signs and symptoms of Chiari I malformation and magnetic resonance imaging (MRI)...
The diagnosis of Chiari I malformation is straightforward in patients with typical signs and symptoms of Chiari I malformation and magnetic resonance imaging (MRI) confirming ≥5 mm of cerebellar tonsillar ectopia, with or without a syrinx. However, in many cases, Chiari I malformation is discovered incidentally on MRI to evaluate global headache, cervical radiculopathy, or other conditions. In those cases, the clinician must consider if cerebellar tonsillar ectopia is related to the presenting symptoms. Surgical decompression of the cerebellar tonsils and foramen magnum in patients with symptomatic Chiari I malformation effectively relieves suboccipital headache, reduces syrinx distension, and arrests syringomyelia progression. Neurosurgeons must avoid operative treatments decompressing incidental tonsillar ectopia, not causing symptoms. Such procedures unnecessarily place patients at risk of operative complications and tissue injuries related to surgical exploration. This chapter reviews the typical signs and symptoms of Chiari I malformation and its variant, Chiari 0 malformation, which has <5 mm of cerebellar tonsillar ectopia and is often associated with syringomyelia. Chiari I and Chiari 0 malformations are associated with incomplete occipital bone development, reduced volume and height of the posterior fossa, tonsillar ectopia, and compression of the neural elements and cerebrospinal fluid (CSF) pathways at the foramen magnum. Linear, angular, cross-sectional area, and volume measurements of the posterior fossa, craniocervical junction, and upper cervical spine identify morphometric abnormalities in Chiari I and Chiari 0 malformation patients. Chiari 0 patients respond like Chiari I patients to foramen magnum decompression and should not be excluded from surgical treatment because their tonsillar ectopia is <5 mm. The authors recommend the adoption of diagnostic criteria for Chiari 0 malformation without syringomyelia. This chapter provides updated information and guidance to the physicians managing Chiari I and Chiari 0 malformation patients and neuroscientists interested in Chiari malformations.
Topics: Humans; Syringomyelia; Arnold-Chiari Malformation; Cranial Fossa, Posterior; Occipital Bone; Headache; Choristoma
PubMed: 38592536
DOI: 10.1007/978-3-031-53578-9_11 -
Journal of Neurosurgery. Pediatrics Apr 2024Congenital anomalies of the atlanto-occipital articulation may be present in patients with Chiari malformation type I (CM-I). However, it is unclear how these anomalies...
The role of occipital condyle and atlas anomalies on occipital cervical fusion outcomes in Chiari malformation type I with syringomyelia: a study from the Park-Reeves Syringomyelia Research Consortium.
OBJECTIVE
Congenital anomalies of the atlanto-occipital articulation may be present in patients with Chiari malformation type I (CM-I). However, it is unclear how these anomalies affect the biomechanical stability of the craniovertebral junction (CVJ) and whether they are associated with an increased incidence of occipitocervical fusion (OCF) following posterior fossa decompression (PFD). The objective of this study was to determine the prevalence of condylar hypoplasia and atlas anomalies in children with CM-I and syringomyelia. The authors also investigated the predictive contribution of these anomalies to the occurrence of OCF following PFD (PFD+OCF).
METHODS
The authors analyzed the prevalence of condylar hypoplasia and atlas arch anomalies for patients in the Park-Reeves Syringomyelia Research Consortium database who underwent PFD+OCF. Condylar hypoplasia was defined by an atlanto-occipital joint axis angle (AOJAA) ≥ 130°. Atlas assimilation and arch anomalies were identified on presurgical radiographic imaging. This PFD+OCF cohort was compared with a control cohort of patients who underwent PFD alone. The control group was matched to the PFD+OCF cohort according to age, sex, and duration of symptoms at a 2:1 ratio.
RESULTS
Clinical features and radiographic atlanto-occipital joint parameters were compared between 19 patients in the PFD+OCF cohort and 38 patients in the PFD-only cohort. Demographic data were not significantly different between cohorts (p > 0.05). The mean AOJAA was significantly higher in the PFD+OCF group than in the PFD group (144° ± 12° vs 127° ± 6°, p < 0.0001). In the PFD+OCF group, atlas assimilation and atlas arch anomalies were identified in 10 (53%) and 5 (26%) patients, respectively. These anomalies were absent (n = 0) in the PFD group (p < 0.001). Multivariate regression analysis identified the following 3 CVJ radiographic variables that were predictive of OCF occurrence after PFD: AOJAA ≥ 130° (p = 0.01), clivoaxial angle < 125° (p = 0.02), and occipital condyle-C2 sagittal vertical alignment (C-C2SVA) ≥ 5 mm (p = 0.01). A predictive model based on these 3 factors accurately predicted OCF following PFD (C-statistic 0.95).
CONCLUSIONS
The authors' results indicate that the occipital condyle-atlas joint complex might affect the biomechanical integrity of the CVJ in children with CM-I and syringomyelia. They describe the role of the AOJAA metric as an independent predictive factor for occurrence of OCF following PFD. Preoperative identification of these skeletal abnormalities may be used to guide surgical planning and treatment of patients with complex CM-I and coexistent osseous pathology.
PubMed: 38579359
DOI: 10.3171/2024.1.PEDS23229 -
Case Reports in Endocrinology 2024We present a case of acromegaly associated with Arnold-Chiari 1 malformation and a literature review regarding this association, mainly focusing on the importance of a...
We present a case of acromegaly associated with Arnold-Chiari 1 malformation and a literature review regarding this association, mainly focusing on the importance of a clear distinction between Chiari malformation and herniation of cerebellar tonsils (CTH). Indeed, in many clinical cases, this distinction has not been properly made and a better description of the radiological findings could be important for the clinical management of these patients. In fact, Arnold-Chiari 1 malformation, as a congenital disease, is not caused by acquired growth hormone (GH) excess, but the latter could worsen pre-existing CTH or even induce it . Therefore, awareness of this condition in the clinical management of acromegaly appears crucial.
PubMed: 38550571
DOI: 10.1155/2024/4733399 -
Child's Nervous System : ChNS :... Jul 2024Chiari II malformation (CM-II) is a congenital malformation of the posterior fossa associated with myelomeningocele. Of the symptomatic patients, 10-33% require surgical... (Review)
Review
PURPOSE
Chiari II malformation (CM-II) is a congenital malformation of the posterior fossa associated with myelomeningocele. Of the symptomatic patients, 10-33% require surgical treatment. To this date, there is not a consensus about the best surgical technique, and whether to do duroplasty.
METHODS
A literature search of the PubMed database and crossed references was performed, per PRISMA guidelines. Data regarding demographic features, extent of cervicomedullary deformity, clinical presentation, surgical techniques, and clinical outcomes were extracted. Pearson's chi-squared test was applied. The p-values under 0.05 were considered statistically significant.
RESULTS
Twenty studies (N = 330) were analyzed. C3 and C4 levels represented 56.4% of the lowest tonsil displacement. The most reported symptom was dysphagia/swallowing dysfunction (53.8%). Suboccipital craniectomy (SOC) and cervical spine expansion (CSE) with duroplasty were the most reported technique. Dural augmentation was performed in 57.4% of the patients. After surgery, 59.6% observed an improvement in symptoms and quality of life, 12.5% were unchanged, and 27.8% had a worsened clinical status. The mortality rate was 2.5% during the first month after surgery, and 17.4% at the last follow-up evaluation. Patients who underwent CSE presented a better clinical outcome (p = 0.002). The SOC procedure could not be correlated with symptom improvement (p = 0.06).
CONCLUSION
CM-II is associated with high morbidity and mortality. An early onset symptomatic CM-II demands intervention, which provided an improvement of outcome in most patients included in this review. The best surgical technique and the exact effect of the surgical management of CM-II on mortality are not yet clear.
Topics: Humans; Arnold-Chiari Malformation; Neurosurgical Procedures; Treatment Outcome
PubMed: 38536450
DOI: 10.1007/s00381-024-06368-x -
Child's Nervous System : ChNS :... May 2024The intrauterine repair of myelomeningocele presents certain advantages and has gained widespread acceptance. It significantly reduces the incidence of Chiari-2... (Review)
Review
The intrauterine repair of myelomeningocele presents certain advantages and has gained widespread acceptance. It significantly reduces the incidence of Chiari-2 anomalies and hydrocephalus, and it is thought to enhance the neurologic outcome. Nevertheless, several issues remain unsettled and there are no negligible disadvantages. After working with patients with myelomeningocele for 30 years, I thought about how we currently treat them. There are ethical, organizational, neurological, obstetrical, and postnatal aspects worth discussing.
Topics: Humans; Meningomyelocele; Arnold-Chiari Malformation; Hydrocephalus; Incidence
PubMed: 38514517
DOI: 10.1007/s00381-024-06365-0 -
World Neurosurgery May 2024Chiari malformation is characterized by inferior displacement of the cerebellar tonsils through the foramen magnum, frequently resulting in strain related headaches, and...
BACKGROUND
Chiari malformation is characterized by inferior displacement of the cerebellar tonsils through the foramen magnum, frequently resulting in strain related headaches, and motor/sensory dysfunction. Chiari decompression technique varies significantly, possibly contributing to frequent revisions. We reviewed revision Chiari decompressions at our institution to determine the primary indications for revision and outcomes after revision.
METHODS
We retrospectively reviewed patients who underwent revision of Chiari decompression at our institution from 2005 to 2020. Demographics, indications for revision surgery, operative techniques, imaging findings, and preoperative/postoperative symptoms were collected. χ test was performed to determine statistical significance using a P < 0.05. Independent predictors of operative outcomes were identified.
RESULTS
A total of 46 patients (91% females, mean age 38.8 years) were included for analysis. The median time to revision surgery was 69.1 months (range 0-364 months) with headache (n = 37, 80%) being the most commonly recurring symptom. Large craniectomy (n = 28, 61%) was the most frequent indication for revision surgery. Thirty-two (70%) patients underwent cranioplasty, 20 (43%) required duraplasty, 15 (33%) required arachnoid dissection, and 15 (33%) required tonsillar reduction during revision surgery. Postrevision follow-up (at 8.9 ± 5.2 months average, range 1-18 months), revealed an average reduction in all Chiari-related symptoms relative to symptoms before the revision.
CONCLUSIONS
The most common indication for revision Chiari decompression was a large craniectomy resulting in cerebellar ptosis. We found that tonsillar reduction paired with modest craniectomy achieved near-complete resolution of symptoms with minimal complications. For patients with recurrent or persistent sequelae of Chiari malformation after decompression, revision may reduce symptom severity.
Topics: Humans; Arnold-Chiari Malformation; Female; Male; Reoperation; Adult; Decompression, Surgical; Retrospective Studies; Middle Aged; Treatment Outcome; Young Adult; Cohort Studies; Decompressive Craniectomy; Postoperative Complications
PubMed: 38490446
DOI: 10.1016/j.wneu.2024.03.026 -
AJNR. American Journal of Neuroradiology Apr 2024Outward convexity of the basiocciput and posterior atlanto-occipital membrane are common in patients with Chiari II malformation associated with an open neural tube...
BACKGROUND AND PURPOSE
Outward convexity of the basiocciput and posterior atlanto-occipital membrane are common in patients with Chiari II malformation associated with an open neural tube defect. We aimed to determine if the severity of these findings correlated with the need for future hydrocephalus treatment.
MATERIALS AND METHODS
A retrospective chart and imaging review identified patients who underwent open neural tube defect repair at a quaternary care pediatric hospital from July 2014 through September 2022. Patients were classified by the need for hydrocephalus treatment and whether they received prenatal or postnatal neural tube defect repair. Measurements of imaging parameters related to posterior fossa maldevelopment and skull base remodeling were performed.
RESULTS
Compared with 65 patients who did not require hydrocephalus treatment, 74 patients who required treatment demonstrated statistically significantly greater mean basiocciput convexity ( < .001). While the mean basiocciput length in the hydrocephalus treatment group was smaller ( < .001), the ratio of basiocciput convexity to length was larger ( < .001). Notably, 100% of patients with a basiocciput convexity of ≥4 mm required hydrocephalus treatment. The mean posterior atlanto-occipital membrane convexity was significantly greater for patients who required hydrocephalus treatment in the postnatal group ( = .02), but not the prenatal group ( = .09).
CONCLUSIONS
Pediatric patients with Chiari II malformation who ultimately required surgical hydrocephalus treatment had greater outward convexity of the basiocciput but had greater posterior atlanto-occipital membrane outward convexity only if the repair was performed postnatally. Together these measurements may be useful in predicting the need for hydrocephalus treatment.
Topics: Pregnancy; Female; Humans; Child; Prognosis; Retrospective Studies; Arnold-Chiari Malformation; Hydrocephalus; Neural Tube Defects; Skull Base; Magnetic Resonance Imaging
PubMed: 38485197
DOI: 10.3174/ajnr.A8142 -
Radiology Case Reports May 2024Chiari malformations are structural defects in the cerebellum that are characterized by the downward displacement of one or both cerebellar tonsils through the foramen...
Chiari malformations are structural defects in the cerebellum that are characterized by the downward displacement of one or both cerebellar tonsils through the foramen magnum. A case report of a female neonate with clinical features of Chiari II malformation is presented. The diagnosis of this condition was made through a combination of clinical and radiological features. In this case, the diagnosis was confirmed by a noncontrast computed tomography (CT) scan of the brain and multiplanar brain magnetic resonance imaging (MRI).
PubMed: 38434787
DOI: 10.1016/j.radcr.2024.01.061 -
World Neurosurgery May 2024This study aimed to examine pneumatization and topographic location of the posterior clinoid process (PCP) in Chiari type I malformation (CIM) for skull base approaches.
OBJECTIVE
This study aimed to examine pneumatization and topographic location of the posterior clinoid process (PCP) in Chiari type I malformation (CIM) for skull base approaches.
METHODS
Computed tomography images of 52 (23 males/29 females) CIM subjects aged 23.87 ± 16.09 years and 71 (26 males/45 females) healthy subjects aged 42.48 ± 21.48 years constituted the study universe.
RESULTS
The distances of PCP to the foramen magnum (P = 0.037), superior orbital fissure (P < 0.001), foramen rotundum (P < 0.001), and foramen ovale (P < 0.001) were smaller, but the distance of PCP to the crista galli (P = 0.038) was greater in CIM patients, compared with normal subjects. In CIM, the fusion between PCP and the anterior clinoid process was observed in 9 sides (8.70%), while in controls it was observed in 12 sides (8.50%). PCP pneumatization was observed in 40 sides (38.50%) in CIM patients, while it was observed in 28 sides (19.70%) in normal subjects. These data displayed that PCP pneumatization was affected by CIM (P < 0.001).
CONCLUSIONS
The distances of PCP to the crista galli and foramen magnum indicate the anterior fossa length and the posterior fossa depth, respectively; thus CIM patients have a longer anterior fossa and a shallow posterior fossa. In addition, the distances of PCP to the superior orbital fissure, foramen rotundum, and foramen ovale indicate the middle fossa width; hence CIM patients have less middle fossa width than normal individuals. CIM patients have an approximately 50% higher PCP pneumatization rate, and this may increase the risk of complications such as cerebrospinal fluid fistula during the application of posterior clinoidectomy.
Topics: Humans; Arnold-Chiari Malformation; Male; Female; Adult; Young Adult; Tomography, X-Ray Computed; Adolescent; Middle Aged; Skull Base; Foramen Magnum; Sphenoid Bone
PubMed: 38431212
DOI: 10.1016/j.wneu.2024.02.130