Benson, John C.

Background Cerebrospinal fluid-venous fistulas (CSFVF) are a common cause of spontaneous intracranial hypotension (SIH). Transvenous embolization has emerged as a reliable treatment option. We review the clinical presentation, imaging, and clinical outcomes of 100 consecutive CSFVF patients who underwent embolization over 2 years. Methods Baseline clinical characteristics, imaging findings (including Bern SIH score), technical outcomes, and long-term imaging and clinical outcomes were collected. All patients had at least 3 months of clinical follow-up and had baseline MRI. 99/100 patients underwent follow-up imaging at ≥3 months post-treatment. Results 100 patients were included. Mean imaging and clinical follow-up duration was 8.3±7.7 months and 15.0±6.8 months, respectively. The mean duration of symptoms before embolization was 40.9±52 months. Mean baseline Bern SIH score was 5.9±3.3. The most common baseline symptoms were headache (96 patients), tinnitus (55 patients), and cognitive dysfunction (44 patients). Technical success rate was 100%. Mean post-treatment Bern SIH score was 0.9±1.6 (P<0.0001). Following treatment, 95% of patients reported significant improvement or resolution in symptoms (58 patients reporting resolution and 37 reporting improvement). 5 patients reported no improvement. There were no major procedural or periprocedural complications. 10 patients had minor procedural complications that did not result in any change in management (Onyx emboli, venous perforation). 19 patients had rebound intracranial hypertension requiring acetazolamide therapy. 7 patients had recurrent fistula at the initially treated level. Conclusions Transvenous embolization of CSFVF in SIH patients is safe and effective with a 95% treatment response, significant improvement in imaging outcomes, and a very low rate of complications.

Abstract Background Neurofibromatosis type 2 (NF2)-related schwannomatosis is an autosomal dominant tumor-predisposition syndrome characterized by bilateral vestibular schwannomas (VS). In patients with VS associated with NF2, vascular endothelial growth factor A inhibitor, bevacizumab, is a systemic treatment option. The aim of this study is to retrospectively evaluate NF2 patient responses to bevacizumab on VS growth and symptom progression. Methods This is a retrospective analysis of patients seen at the Mayo Clinic Rochester Multidisciplinary NF2 Clinic. Results Out of 76 patients with NF2 evaluated between 2020 and 2022, we identified 19 that received treatment with bevacizumab. Thirteen of these patients discontinued bevacizumab after median treatment duration of 12.2 months. The remaining 6 patients are currently receiving bevacizumab treatment for a median duration of 9.4 months as of March, 2023. Fifteen patients had evaluable brain MRI data, which demonstrated partial responses in 5 patients, stable disease in 8, and progression in 2. Within 6 months of bevacizumab discontinuation, 5 patients had rebound growth of their VS greater than 20% from their previous tumor volume, while 3 did not. Three patients with rebound growth went on to have surgery or irradiation for VS management. Conclusions Our single-institution experience confirms prior studies that bevacizumab can control progression of VS and symptoms associated with VS growth. However, we note that there is the potential for rapid VS growth following bevacizumab discontinuation, for which we propose heightened surveillance imaging and symptom monitoring for at least 6 months upon stopping anti-VEGF therapy.

Abstract BACKGROUND Neurofibromatosis type 2-related schwannomatosis (NF2) is an autosomal dominant tumor-predisposition syndrome characterized by bilateral vestibular schwannomas (VS) as well as other nervous system tumors. Management decisions for NF2-related VS are typically predicated on tumor size, associated symptoms, patient age, and comorbidities. Observation, surgical resection, and stereotactic radiosurgery can be viable options. In patients with VS associated with NF2, vascular endothelial growth factor A (VEGF-A) inhibitor, bevacizumab, is a systemic treatment option. In this single institution study, we review our clinical experience in patients with NF2 who received bevacizumab for VS and evaluate the effect of bevacizumab treatment on VS growth and symptom progression. MATERIAL AND METHODS This is a retrospective analysis of patients seen at the Mayo Clinic Rochester Multidisciplinary NF2 Clinic. Three-dimensional volumetric data for VS were measured using manual segmentation with Visage PACS software under the direct supervision of a board-certified neuroradiologist. RESULTS Out of 76 patients with NF2 evaluated in the past 3 years, we identified 19 that received treatment with bevacizumab. Median age of NF2 diagnosis was 19 years (range 0.5-61) with a median NF2 phenotype severity score of 2 (range 1-3). Thirteen of these patients have discontinued bevacizumab, accounting for a median duration of 12.2 months (range 3.3-88 months) of bevacizumab treatment. Bevacizumab was discontinued due to hypertension (n=5), proteinuria and renal dysfunction (n=3), tumor progression (n=2), fatigue or other intolerance (n=2), or non-compliance (n=1). The remaining 6 patients are currently receiving bevacizumab treatment for a median duration of 9.4 months as of March 2023 (range 3.7-48.3 months). Fifteen patients had brain MRI data available to evaluate VS change during bevacizumab treatment, with partial response observed in 5 patients, stable disease in 8, and progression in 2. Ten of the 13 patients who stopped bevacizumab had MRI data to evaluate VS change following treatment termination. Within 6 months of bevacizumab discontinuation, 6 patients had rebound growth of their VS between 21-95% from their previous tumor volume, while 4 did not. Three patients with rebound growth went on to have surgery or irradiation for VS management. CONCLUSION Our single institution experience confirms that bevacizumab can slow progression of VS and symptoms associated with VS growth. However, we note that there is the potential for rapid VS growth following bevacizumab discontinuation, for which we propose heightened surveillance imaging and symptom monitoring for at least 6 months upon stopping anti-VEGF therapy.

We present an updated ultrafast dynamic computed tomography myelography technique that can be used for the localization of spontaneous spinal cerebrospinal fluid leaks in the setting of spontaneous intracranial hypotension. This has over twice the temporal resolution of previously described techniques at the same radiation dose output.

Purpose Imaging changes in the pituitary volume during pregnancy remains scantly researched. This study set out to assess the differences in total, anterior, and posterior pituitary volume in pregnant women compared to nulliparous and post-partum women. Materials and Methods A retrospective review was completed of women that had undergone MRI imaging of the brain. Patients were divided into three cohorts: pregnant, nulliparous, and post-partum (defined as being within 12 months of delivery). Anterior and posterior pituitary volumes were manually measured. Results 171 patients were included, of which 68 were pregnant, 52 were post-partum, and 51 were nulliparous. The average anterior (621.0 ± 171.6 mm 3 ) and total (705.4 ± 172.2 mm 3 ) pituitary volumes were significantly larger in pregnant patients than nulliparous women (522.6 ± 159.8 mm 3 and 624.5 ± 163.7 mm 3 , respectively) ( p = .002 and p = .01, respectively). The posterior pituitary volume was significantly smaller in pregnant women (84.4 ± 32.9 mm 3 ) compared to both post-partum (101.2 ± 42.0 mm 3 ) and nulliparous (102.0 ± 46.1 mm 3 ) women ( p = .02 for both). Conclusions The anterior and total pituitary volumes are significantly larger during pregnancy persisting into the post-partum period. The posterior pituitary volume, conversely, decreases during pregnancy, and returns to its normal size in the post-partum period.

AbstractObjectiveTo evaluate the magnetic resonance (MR) image artifact and image distortion associated with the two transcutaneous bone conduction implants currently available in the United States.Study DesignCadaveric study.MethodsTwo cadaveric head specimens (1 male, 1 female) were unilaterally implanted according to manufacturer guidelines and underwent MR imaging (General Electric and Siemens 1.5 T scanners) under the following device conditions: (1) no device, (2) Cochlear Osia with magnet and headwrap, (3) Cochlear Osia without magnet, and (4) MED‐EL Bonebridge with magnet. Maximum metal mitigation techniques were employed in all conditions, and identical sequences were obtained. Blinded image scoring (diagnostic vs nondiagnostic image) was performed by experienced neuroradiologists according to anatomical subsites.ResultsAll device conditions produced artifact and image distortion. The Osia with magnet produced diagnostic T1‐ and T2‐weighted images of the ipsilateral temporal bone, however, non‐echo planar imaging diffusion‐weighted imaging (DWI) was nondiagnostic. The Osia without magnet scanned on the Siemens MR imaging demonstrated the least amount of artifact and was the only condition that allowed for diagnostic imaging of the ipsilateral temporal bone on DWI. The Bonebridge produced a large area of artifact and distortion with the involvement of the ipsilateral and contralateral temporal bones.ConclusionIn summary, of the three device conditions (Osia with magnet, Osia without magnet, and Bonebridge), Osia without magnet offered the least amount of artifact and distortion and was the only condition in which diagnostic DWI was available for the middle ear and mastoid regions on the Siemens MR imaging scanner.

Background Intra-osseous vessels are normal anatomic structures in the calvarium and skull base. On imaging, these structures—particularly venous lakes—can mimic pathologic abnormalities. This study sought to assess the prevalence of veins and lakes in the skull base on MRI. Materials and Methods A retrospective review was completed of consecutive patients that underwent contrast-enhanced MRI imaging of the internal auditory canals. The clivus, jugular tubercles, and basio-occiput were assessed for the presence of both intra-osseous veins (serpentine and/or branching vessels) and venous lakes (well-circumscribed round or oval enhancing structures). Vessels in the adjacent synchondroses major foramina were excluded. Three board-certified neuroradiologists performed independent blinded reviews, with discrepancies agreed upon by consensus. Results 96 patients were included in this cohort (58.3% female). Mean age was 58.4 years (range = 19–85). At least one intra-osseous vessel was identified in 71 (74.0%) patients. 67 (70.0%) had at least one skull base vein, and 14 (14.6%) had at least one venous lake. Both vessel subtypes were observed in 8.3% of patients. Vessels were more commonly observed in women, though this did not reach statistical threshold ( p = 0.56). Age was not associated with the presence of vessels (0.59) or vessel location ( p values ranged from 0.44–0.84). Conclusions Intra-osseous skull base veins and venous lakes are relatively common findings on MRI. Both vascular structures should be considered normal anatomy, and care should be taken to not confuse these for pathologic entities.

Introduction Spontaneous intracranial hypotension (SIH) caused by a spinal cerebrospinal fluid (CSF) leak classically presents with orthostatic headache. Digital subtraction myelography (DSM) has a well-established diagnostic yield in the absence of extradural spinal collection. At our institution, DSM is followed by lateral decubitus CT myelogram (LDCTM) in the same decubitus position to increase diagnostic yield of the combined study. We evaluated the incremental diagnostic yield of LDCTM following negative DSM and reviewed patient outcomes. Methods Retrospective review of consecutive DSMs with subsequent LDCTM from April 2019 to March 2021 was performed. Combined reports were reviewed, and studies with positive DSMs were excluded. Of the exams with negative DSM, only studies with LDCTM reports identifying potential leak site were included. Interventions and follow-up clinical notes were reviewed to assess symptoms improvement following treatment. Results Of the 83 patients with negative DSMs, 11 (13.2%) had positive leak findings on LDCTMs, and 21 (25.3%) were equivocal. Of 11 positive LDCTMs, 6 leaks were nerve sheath tears (NSTs) and 5 were CSF-venous fistulas (CVFs). 10/11 (90.9%) had intervention and follow-up, with 9/10 (90%) having positive clinical outcome. Of the 21 equivocal LDCTM patients (19 CVFs and 2 NSTs), 15 (71.4%) had interventions and follow-up, with 3/15 (20.0%) with positive clinical outcomes. Conclusion LDCTM following negative DSM has an incremental diagnostic yield up to 38.6%, with up to 14.5% of positive patient outcomes following treatment. LDCTM should be considered after DSM to maximize diagnostic yield of the combined exam.

Abstract Objective To describe the technique, safety profile, and outcome of computed tomography (CT)–guided atlanto-axial lateral articulation injections performed at our institution. Methods Consecutive cases of all CT-guided atlanto-axial injections performed from January 2017 to April 2022 at our institution were searched in the electronic medical records. Patient charts were reviewed for demographics, characterization of pain, potential altered anatomy, pain level before and immediately after the procedure, procedure technique, complications, and follow-up outcomes, if available. Results Forty-five injections in 40 different patients were included. The average age was 67.4 years, and 28 (70%) of the patients were female. Of the 45 injections, 43 (96%) were technically successful. The average change in pain score (0–10) from immediately before to immediately after the injection was –3.36 (SD = 2.87, range = –8 to +3). Of all injections, 14 (31%) had a postprocedural pain score of zero. In 2 cases (4%), patients reported an increase in pain score immediately after the injection. In 3 cases (7%), transient non–vertebral artery vascular uptake of contrast was documented during the procedure, which could be cleared with needle repositioning. There were no complications. Conclusion CT-guided atlanto-axial lateral articulation injection is a safe procedure with a high technical success rate. It allows for direct visualization of vital structures and provides an alternative option to the traditional fluoroscopic guidance, especially in cases of prior technically unsuccessful fluoroscopically guided injection or altered anatomy.

Abstract Background and Purpose Artifact from cochlear implant electrodes degrades image resolution on CT. Here, we describe the use of coregistered pre‐ and postoperative CT images to reduce metallic artifact from the electrodes to assess its position more accurately within the cochlear lumen. Methods Pre‐ and postoperative CTs were reviewed after coregistration/overlay of both exams. Images were evaluated by two neuroradiologists for scalar location of electrodes tip (± scalar translocation), tip fold over, and angular depth of insertion. Results Thirty‐four patients were included in the final cohort. Transscalar migration was present in three (8.8%) cases (one case demonstrated tip fold over), with initial disagreement regarding transscalar migration in 1 out of 34 patients (2.9%). Agreement regarding depth of insertion was present in 31 (91.1%) cases. Five‐point Likert scales were used to compare the ability to resolve the proximity of electrodes to the lateral/outer cochlear wall without and with overlay, which is a qualitative measure of artifact from the array. Likert scores showed definitive benefit of metal artifact reduction using overlayed images with an average score of 4.34. Conclusion This study demonstrates a novel technique of using fused coregistration of pre‐ and postoperative CTs for the purpose of artifact reduction/electrode localization. It is anticipated that this technique will permit more accurate localization of the electrodes for improvement in surgical technique and electrode array design.