Glial Fibrillary Acidic Protein Astrocytopathy: Review of Pathogenesis, Imaging Features, and Radiographic Mimics.

Glial fibrillary acidic protein (GFAP) astrocytopathy is a recently described autoimmune inflammatory disorder of the CNS characterized by the presence of specific antibodies targeting the intracellular filament protein in mature astrocytes. The pathogenesis is heterogeneous and poorly understood, with around 20%-34% of cases occurring as a paraneoplastic syndrome, most frequently associated with ovarian teratomas. It presents clinically as acute or subacute encephalomyelitis, and the diagnosis relies on imaging and detection of GFAP-Immunoglobulin (GFAP-IgG) in the CSF. Characteristic imaging findings include linear perivascular enhancement in the white matter extending in a radial pattern. Other imaging findings include periependymal enhancement, longitudinally extensive cord signal changes, intramedullary enhancement, optic neuritis, and papillitis. There is significant imaging overlap with other neuroinflammatory diseases like neuromyelitis optica spectrum disorder and lymphoproliferative conditions. GFAP astrocytopathy is characteristically responsive to steroids with, however, a significant rate of relapse. Currently, literature on this novel entity is limited with no established diagnostic criteria or standard treatment regimen. This comprehensive review explores the clinical, radiographic, and histopathologic aspects of GFAP astrocytopathy, shedding light on its complex nature and potential diagnostic challenges. The paper highlights the neuroimaging findings with a focus on differentiating GFAP astrocytopathy from other neuroinflammatory disorders.

Updates from the International League Against Epilepsy Classification of Epilepsy (2017) and Focal Cortical Dysplasias (2022): Imaging Phenotype and Genetic Characterization.

The International League Against Epilepsy (ILAE) is an organization of 120 national chapters providing the most widely accepted and updated guidelines on epilepsy. In 2022, the ILAE Task Force revised the prior (2011) classification of focal cortical dysplasias to incorporate and update clinicopathologic and genetic information, with the aim to provide an objective classification scheme. New molecular-genetic information has led to the concept of "integrated diagnosis" on the same lines as brain tumors, with a multilayered diagnostic model providing a phenotype-genotype integration. Major changes in the new update were made to type II focal cortical dysplasias, apart from identification of new entities, such as mild malformations of cortical development and cortical malformation with oligodendroglial hyperplasia. No major changes were made to type I and III focal cortical dysplasias, given the lack of significant new genetic information. This review provides the latest update on changes to the classification of focal cortical dysplasias with discussion about the new entities. The ILAE in 2017 updated the classification of seizure and epilepsy with 3 levels of diagnosis, including seizure type, epilepsy type, and epilepsy syndrome, which are also briefly discussed here.

Intracranial aneurysms in patients with acute ischemic stroke prevalence and influence on mechanical thrombectomy over 14 years in a tertiary-care center.

INTRODUCTION: The prevalence of intracranial aneurysms (IA) in patients with acute ischemic stroke (AIS) requiring mechanical thrombectomy (MT) is unclear. OBJECTIVE: To describe the prevalence of IA in patients with AIS and their influence on MT. MATERIALS & METHODS: This is a retrospective cohort study on all patients admitted with a diagnosis of AIS from January 2008 to March 2022 at a tertiary academic center. The records were reviewed for demographic, clinical, imaging, and outcomes data. Only patients who had CTA at admission were included in this analysis. RESULTS: Among 2265 patients admitted with AIS, this diagnosis was confirmed in 2113 patients (93.3 %). We included 1111 patients (52.6 %) who had head CTA and 321 (28.9 %) who underwent MT. The observed prevalence of aneurysms on CTA was 4.5 % (50/1111 patients), and 8 (16 %) had multiple aneurysms. MT was performed in 7 patients harboring IAs: 6 ipsilateral (5 proximal and 1 distal to the occlusion)and 1 contralateral aneurysm.. The patient with a contralateral aneurysm had a TICI 2B score In patients with ipsilateral aneurysms, TICI 2B or 3 was achieved in 3 cases (50 %), which is significantly lower than historical control of MT (91.6 %) without IA (p = 0.01). No aneurysms ruptured during MT. The aneurysm noted distal to the occlusion was mycotic. CONCLUSION: In this analysis, the observed prevalence of IA in patients with AIS was 4.5%. Ipsilateral aneurysms (proximal or distal to the occlusion site) deserve particular attention, given the potential risk of rupture during MT. Aneurysms located distal to the occlusion were mycotic and the rate of recanization in patients with ipsilateral aneurysms was low compared to historical controls. Further studies are needed to improve the outcomes in patients with IA requiring MT.

Chronic hippocampal subfield damage in transient global amnesia revealed by 7T MRI: All is not reversible?

Transient global amnesia (TGA) is a neurological condition characterized by temporary memory loss and classically associated with a reversible unilateral punctate focus of restricted diffusion in the cornu ammonis 1 (CA1) region of the hippocampus. Historically, the lesions were considered to be transient in nature with no long-term imaging abnormality. However, more recent studies have challenged the concept that there are no long-term neurological sequelae. In line with this evidence, we explore the role of ultra-high-resolution imaging using 7 Tesla MRI to evaluate for long-term imaging abnormalities in a 63-year-old woman with a typical clinical course and acute TGA imaging findings. The 7 Tesla MRI revealed a residual lesion on susceptibility-weighted imaging (SWI) with evidence of gliosis and volume loss at the site of the acute lesion in CA1 eight months after the acute episode. This case challenges the traditional mantra of TGA as a fully reversible condition with no long-term imaging findings, suggesting the need for further research using ultra-high-field MRI to determine TGA's potential long-term imaging sequelae and any association with neurocognitive sequelae.

Newly Recognized Genetic Tumor Syndromes of the CNS in the 5th WHO Classification: Imaging Overview with Genetic Updates.

The nervous system is commonly involved in a wide range of genetic tumor-predisposition syndromes. The classification of genetic tumor syndromes has evolved during the past years; however, it has now become clear that these syndromes can be categorized into a relatively small number of major mechanisms, which form the basis of the new 5th edition of the World Health Organization book (beta online version) on genetic tumor syndromes. For the first time, the World Health Organization has also included a separate chapter on genetic tumor syndromes in the latest edition of all the multisystem tumor series, including the 5th edition of CNS tumors. Our understanding of these syndromes has evolved rapidly since the previous edition (4th edition, 2016) with recognition of 8 new syndromes, including the following: Elongator protein complex-medulloblastoma syndrome, BRCA1-associated protein 1 tumor-predisposition syndrome, DICER1 syndrome, familial paraganglioma syndrome, melanoma-astrocytoma syndrome, Carney complex, Fanconi anemia, and familial retinoblastoma. This review provides a description of these new CNS tumor syndromes with a focus on imaging and genetic characteristics.

Cervical Osteomyelitis and Diskitis as a Complication of Neopharyngeal Breakdown: A Multisite Case Series Review.

Laryngectomy and pharyngectomy are surgical options for advanced laryngeal or pharyngeal squamous cell carcinoma. Cervical osteomyelitis-diskitis, occurring when there is dehiscence of the posterior neopharyngeal wall, is an uncommon complication of laryngopharyngectomy. This case series describes imaging findings of pharyngoesophageal wall breakdown with subsequent cervical spine infection and demonstrates that most of these patients had undergone prior esophageal or neopharyngeal dilations for benign posttreatment stricture. Neck pain, fever, or serologic evidence of infection should prompt careful evaluation for osteomyelitis-diskitis and assessment for neopharyngeal breakdown and sinus tract formation, especially in the postdilation setting.

Amyloid-related Imaging Abnormalities in Alzheimer Disease Treated with Anti-Amyloid-ß Therapy.

Alzheimer disease (AD) is the most common form of dementia worldwide. Treatment of AD has mainly been focused on symptomatic treatment until recently with the advent and approval of monoclonal antibody (MAB) immunotherapy. U.S. Food and Drug Administration-approved drugs such as aducanumab, as well as upcoming newer-generation drugs, have provided an exciting new therapy focused on reducing the amyloid plaque burden in AD. Although this new frontier has shown benefits for patients, it is not without complications, which are mainly neurologic. Increased use of MABs led to the discovery of amyloid-related imaging abnormalities (ARIA). ARIA has been further classified into two categories, ARIA-E and ARIA-H, representing edema and/or effusion and hemorrhage, respectively. ARIA is thought to be caused by increased vascular permeability following an inflammatory response, leading to the extravasation of blood products and proteinaceous fluid. Patients with ARIA may present with headaches, but they are usually asymptomatic and ARIA is only diagnosable at MRI; it is essential for the radiologist to recognize and monitor ARIA. Increased incidence and investigation into this concern have led to the creation of grading scales and monitoring guidelines to diagnose and guide treatment using MABs. Cerebral amyloid angiopathy has an identical pathogenesis to that of ARIA and is its closest differential diagnosis, with imaging findings being the same for both entities and only a history of MAB administration allowing differentiation. The authors discuss the use of MABs for treating AD, expand on ARIA and its consequences, and describe how to identify and grade ARIA to guide treatment properly. ©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center See the invited commentary by Yu in this issue.

7T MRI in transient ischemic attacks: Have we only seen the tip of the iceberg?

Transient ischemic attack (TIA) has gained significant attention recently due to the increased incidence of subsequent stroke. However, there are many nonvascular clinical mimics of TIA, creating a need for improved biomarkers to identify a vascular origin. Following the recent approval of ultra-high field (UHF) 7T MRI in clinical practice, several clinical studies have highlighted its added utility in neuroimaging compared to lower-field 1.5T and 3T MRI, particularly in epilepsy and multiple sclerosis. Our case series of three patients with TIA illustrates that 7T MRI can depict small areas of intracortical microhemorrhages and microinfarctions, which could not be resolved with 3T or 1.5T MRI. There are currently no reports of intracortical localization of microhemorrhages in patients with TIA. This discovery may enhance our understanding and characterization of cerebrovascular abnormalities in TIAs. In addition, UHF imaging could potentially be utilized to distinguish transient neurological episodes secondary to cerebrovascular events from other differential considerations. Our cases highlight the underestimation of imaging abnormalities in cases of TIA and support the potential expanded application of clinical 7T to assess patients with TIA. Future studies are necessary at 7T redundant to determine the true incidence of such lesions in TIA and to examine the correlation between cortical microhemorrhages and subsequent ischemic stroke, hemorrhagic events, and neurocognitive impairment.

Sinonasal Schwannomas: Imaging Findings and Review of Literature.

OBJECTIVE: Schwannomas are common nerve sheath tumors and may occur anywhere in the body. 4% of head and neck schwannomas occur in the sinonasal cavity, and fewer yet have an intracranial component, making these presentations extremely rare. Furthermore, schwannomas present with nonspecific imaging signs and can only be definitively differentiated via histopathologic review, leading to misdiagnosis as various nasal tumors. We aim to conduct a review of published literature on sinonasal schwannomas with and without intracranial extension and provide additional case representations. METHODS: A literature review was conducted using the PubMed Database with the terms "sinonasal schwannoma," "intracranial," "anterior skull base," and "schwannoma." Results were reviewed, and additional cases identified were referenced and included in the study. Inclusion criteria were any case with intracranial extension of the schwannoma. There were no exclusion criteria. Review data was compiled into Excel and used for data analysis and comparison. Additionally, a search was done within our institution to identify additional cases of sinonasal schwannoma. RESULTS: We identified 17 cases of sinonasal schwannoma with intracranial extension, five from our institution and twelve from literature. Analysis revealed: 8 females (47%), 9 males (53%), 9 patients presented with headaches (53%), 6 patients presented with anosmia (35%), 4 patients presented with nasal obstruction (24%), and 2 patients with no symptoms (12%). Mean age and median were 39.4 ± 10.1 and 40, respectively. For treatment, 4 patients underwent endoscopic resection (24%), 11 underwent craniotomy (65%), and data was unavailable for 2 patients. Post-treatment complications occurred in 6 patients, 5 had CSF leaks (29%) and 1 had a hematoma (6%). CONCLUSION: We identified and discussed 17 cases of sinonasal schwannoma with intracranial extension. We hope our review provides insight for clinicians to maintain schwannoma as a potential differential when evaluating nasal and anterior skull base masses.

Transvenous embolization of cerebrospinal fluid-venous fistulas: Independent validation and feasibility of upper-extremity approach and using dual-microcatheter and balloon pressure cooker technique.

BACKGROUND: Transvenous embolization is emerging as a promising treatment for cerebrospinal fluid-venous fistulas (CVF) associated with spontaneous intracranial hypotension (SIH). OBJECTIVE: To perform an independent validation of the efficacy and safety of the procedure and describe the procedural techniques used at our institution. METHODS: A retrospective review was performed including consecutive patients with SIH who had undergone CVF embolization with 3-month clinical and imaging follow-up. Clinical evaluation included the Patient Global Impression of Change (PGIC) Scale and six-item Headache Impact Test (HIT-6). Bern SIH score was used for imaging evaluation on brain MRI. Post-treatment changes in scores were assessed by Wilcoxon signed rank test. Procedural technical details, including use of upper-extremity access and dual-microcatheter pressure cooker technique, were recorded. RESULTS: 18 patients (13 female, median age 60 years) were included. 17 (94%) procedures were performed with upper-extremity access and 12 (67%) using dual-microcatheter pressure cooker technique. After embolization, 16 (89%) patients reported much or very much improved at follow-up PGIC; median (IQR) HIT-6 score improved from 68 (62-72) to 36 (36-38) and Bern SIH score improved from 8 (6-8) to 3 (1.5-3.5), p values <0.001. Side effects were transient embolization site back pain in 15 (83%) and rebound intracranial hypertension requiring medical management in 9 (50%) patients. HIT-6 and Bern SIH score changes were similar between conventional and pressure cooker techniques (p values >0.05). CONCLUSION: Transvenous embolization is independently validated as a highly effective and safe treatment for CVF and is feasible using upper-extremity venous access. Dual-microcatheter and balloon/coil pressure cooker techniques may be used to optimize distribution of embolic material and potentially, treatment efficacy.

A novel technique for safe percutaneous biopsy of a petrous apex lesion.

Lesions within the skull base are the most challenging targets for percutaneous biopsy due to the likelihood of encountering a critical structure along any needle trajectory. Due to ICA proximity, the petrous apex is considered unsafe. We describe a novel percutaneous CT-guided approach for biopsying a petrous apex lesion via a contralateral mandibular condylar notch (subzygomatic approach). To our best knowledge, this approach has not been reported and can be safely employed with thorough planning.

Lateral Decubitus Dynamic CT Myelography with Real-Time Bolus Tracking (dCTM-BT) for Evaluation of CSF-Venous Fistulas: Diagnostic Yield Stratified by Brain Imaging Findings.

BACKGROUND AND PURPOSE: CSF-venous fistulas (CVFs) associated with spontaneous intracranial hypotension (SIH) may have a transient appearance, relative to contrast arrival, which may influence the diagnostic performance of lateral decubitus CT myelography (CTM). We developed a dynamic CTM protocol using real-time bolus-tracking (dCTM-BT) to improve the temporal resolution and standardize the timing of CTM acquisitions post-intrathecal contrast administration. The purpose of our study was to evaluate the feasibility of the dCTM-BT technique and evaluate its diagnostic yield for CVF detection, stratified by brain MRI SIH findings. MATERIALS AND METHODS: Patients with suspected SIH without extradural fluid collection on spine MRI who underwent dCTM-BT were retrospectively reviewed. CT bolus monitoring was performed at the upper thoracic level. Following the visualization of dense intrathecal contrast, at least 3 CTM acquisitions of the spine were obtained and reviewed by 2 neuroradiologists. The Bern SIH score was calculated on the brain MRI. The diagnostic yield for CVF detection was evaluated, stratified by Bern score categories and a receiver operating characteristic (ROC) analysis. RESULTS: Out of 48 patients, 23 (48%) had a CVF on dCTM-BT, located at T1-5 (n = 4), T6-12 (n = 18), L1 (n = 1), with 70% on the right. CVF was identified in 22/22 (100%) of patients who had a high Bern score, 1/7 (14%) of those who had an intermediate score, and 0/19 (0%) of those who had a low score. The area under the ROC curve was 0.99 (95% CI, 0.98-1.00). The optimal cutoff was a Bern score of ≥5 (96% sensitivity, 100% specificity). CONCLUSIONS: dCTM-BT is feasible and has excellent diagnostic performance for CVF identification/localization. The Bern score is strongly associated with CVF detection and may help inform who will benefit from dCTM-BT.

Oculomotor nerve root split: incidental finding on MRI-case report and literature review.

BACKGROUND: The oculomotor nerve (OMN) innervates the pupil, ciliary body, upper eyelid, and extraocular muscles through two divisions: a superior division that innervates the levator palpebrae superioris (LPS) and superior rectus (SR), and an inferior division that supplies the medial rectus (MR), inferior rectus (IR), inferior oblique (IO), and parasympathetic fibers to the pupil and ciliary body. We present a case of complete splitting of the cisternal segment of bilateral OMNs that was discovered incidentally on magnetic resonance imaging (MRI) in a patient who had no ocular complaints. CASE REPORT: A 69-year-old patient was found to have bilateral splitting of the cisternal segments of OMNs during an MRI for trigeminal neuralgia workup. Both nerves sprang from the midbrain as distinct roots. They were symmetric on the right and minimally asymmetric on the left. On both sides, the medial root was slightly inferiorly situated. The patient had no visual problems and continued to function normally. A review of the literature for similar cases identified no such variants; however, it did identify eight examples of OMN fenestrations produced by aneurysms (AN), six of which had no OMN palsy symptoms. CONCLUSION: An anatomic variant of split bilateral OMN cisternal segments is described. The superior and inferior divisions may have different brainstem origins. Although this variant is an anatomic curiosity, it may have clinical significance and explain the various presentation of compressive OMN palsies.

Spinal gout diagnosed by dual-energy CT: A case report.

Axial gout is an atypical presentation of gout caused by monosodium urate deposition in the axial skeleton. Spinal gout presents nonspecifically and can be a difficult diagnosis. The diagnosis of gout is a clinical one, with imaging and labs providing supporting evidence. Current imaging modalities such as magnetic resonance, computed tomography, and X-ray can be nonspecific and lead to invasive procedures for diagnosis. Dual-energy computed tomography allows clear visualization of urate collection and is a valuable tool to make a confident diagnosis of spinal gout. Here, we present a case of a man with longstanding severe gout in which dual-energy computed tomography played a key role in diagnosis.

Clinical and imaging features of spinal extradural arachnoid cysts: a retrospective study of 50 cases.

PURPOSE: Spinal extradural arachnoid cysts (SEDACs) are thought to arise from leakage of CSF through a spinal dural defect. This study investigates the demographics and imaging spectrum of SEDACs at our academic institution and compares them with those reported in the literature. METHODS: Fifty cases with documented MRI diagnosis of SEDAC, Nabors criteria type I meningeal cyst (MC), were identified from retrospective review of imaging records between 1999 and 2020. Patient demographics, presenting symptoms, cyst characteristics, and management outcomes were studied. Statistical analysis was performed to determine associations between maximum cyst size and presenting symptoms along with other imaging findings. RESULTS: In all 50 subjects, SEDACs were solitary (single) and sporadic (non-familial). The majority were incidental (62%), located posteriorly (92%) and laterally (80%) in the thoracic and thoracolumbar regions (34%, 30%). They were associated with mild mass effect upon the thecal sac (50%) and bone remodeling (92%). Among symptomatic SEDACs, back pain and radiculopathy were the most reported (68%). Larger cysts were located caudally in the spinal canal, and were associated with greater thecal mass effect, bone remodeling, and septations. Four out of six subjects who underwent surgical management had complete or partial remission. One had cyst recurrence. CONCLUSION: In this largest series of SEDACs, most were discovered incidentally, stable over time, and located in the thoracic spine dorsal to the thecal sac. When symptomatic, back pain and radiculopathy were the most common presenting symptoms. Treatment with complete surgical excision may yield the best results for symptomatic lesions.

Calcifying pseudoneoplasms of the neuraxis (CAPNON): The great tumor mimicker.

Calcifying pseudoneoplasms of the neuraxis (CAPNON) are very rare intracranial lesions with less than 50 cases reported in literature. These are non-neoplastic in etiology and despite having unique imaging characteristics, are often misdiagnosed as a neoplastic condition like meningioma, chordoma and gliomas. These do not have any predilection for any age, gender or intracranial location and can be seen in a wide range of age groups. Despite having an imaging overlap with neoplastic conditions, CAPNONs have classic histopathologic findings including chondromyxoid matrix, palisading spindle cells and calcific or ossific metaplasia. As more cases are being described in literature the imaging features are also being better defined. We discuss the clinical, imaging and histopathological findings of 2 cases of CAPNON mimicking posterior fossa meningioma and glial neoplasm.

New bone formation over dehiscent semicircular canal with cartilage cap.

PURPOSE: Cartilage cap resurfacing is a method to seal a superior semicircular canal dehiscence. The purpose of this study was to evaluate the detection of new bone formation after surgical placement of a cartilage cap over a dehiscent semicircular canal. METHODS: In this retrospective review, two neuroradiologists blinded to each other's interpretation reviewed the temporal bones of 20 patients, five of which had a pre-operative computed tomography (CT) exam which was interpreted as unilateral superior semicircular canal dehiscence and with new bone formation following repair on follow-up CT. There were also 15 control subjects. Each neuroradiologist was blinded to history, including post-operative changes, and asked to determine if there was a dehiscence or no dehiscence. RESULTS: Out of the 15 controls, there was 100% inter-observer agreement. On the five post-operative patients, there was agreement in 4/5 that there was no dehiscence post-operatively and 1/5 agreement of dehiscence post-operatively, but ectopic bone adjacent to the dehiscence. CONCLUSION: Our results indicate that new bone formation can be seen at the site of cartilage cap placement over the dehiscence and be interpreted as bony closure of the dehiscence.

Obliterative sinusitis: An underreported clinical entity.

Obliterative paranasal sinusitis is a rare sequela and end stage of chronic rhinosinusitis, which is often overlooked on imaging. It is an exuberant form of neo-osteogenesis characterized by complete or partial obliteration of the sinus cavity by new bone formation. This article presents a series of cases of obliterative sinusitis involving the sphenoid and maxillary sinuses. It is important to comment on the presence of obliterative sinusitis in the radiology report and not confuse it for native bone, fibro-osseous lesion, or arrested pneumatization, as this may have clinical implications for patients being considered for surgery. Given its potential implications for severity of sinusitis as well as prognostic significance for outcomes following endoscopic sinus surgery, awareness and timely identification of this entity is important to guide referring clinicians.