Madhavan, Ajay A.

Cerebrospinal fluid (CSF)–venous fistulas are an increasingly recognized source of spontaneous intracranial hypotension, for which endovascular embolization has emerged as an effective treatment option.1–3 Advances in diagnostic imaging have improved detection of CSF–venous fistulas throughout the cervical, thoracic, and lumbar spine; however, identification of lesions at the cranial and caudal extremes of the spine remains challenging.4 In video 1, we present the novel case of an anterior condylar confluence CSF–venous fistula arising from a hypoglossal canal nerve root sleeve diverticulum. We demonstrate the diagnostic evaluation, preprocedural planning, and transvenous embolization of the fistula using the pressure cooker technique, highlighting key technical considerations for navigating this uncommon venous anatomy. Finally, we review the patient’s postprocedural course and imaging findings demonstrating radiographic resolution of spontaneous intracranial hypotension. Video 1 Endovascular embolization of a cerebrospinal fluid–venous fistula arising from a hypoglossal canal nerve root sleeve diverticulum using a transvenous pressure cooker technique.

Background Spontaneous intracranial hypotension (SIH) results from cerebrospinal fluid (CSF) leakage due to spinal dural tears or CSF–venous fistulas. Orthostatic headache is the hallmark presentation, though severe downward displacement of the brainstem may lead to altered consciousness or coma. Definitive treatments include targeted epidural blood patches, venous embolization, or surgical repair. Methods This article reviews the role of the Trendelenburg position as a temporizing measure in the acute management of SIH. We describe the correct technique, physiologic rationale, and practical considerations for its application, with attention to both therapeutic and diagnostic utility. Discussion Positioning the patient with the feet elevated above the head can reduce brain sag and provide short-term symptomatic relief while awaiting definitive treatment. Although the Trendelenburg position is widely used in practice, supporting evidence remains limited, and clinicians must be aware of its benefits, indications, and inherent limitations. Its appropriate application may assist in stabilizing patients with acute or severe SIH, particularly those with impaired consciousness, until more definitive interventions are pursued.

A 49-year-old woman presented with a dorsal column-predominant sensory myelopathy secondary to superficial siderosis. She had Marfan syndrome and was found to have dural ectasia. Superficial siderosis results from subpial haemosiderin deposition due to chronic subarachnoid space bleeding, often from a dural pathology, such as a tear. Dural ectasia is common in Marfan syndrome, but superficial siderosis is not. Gait ataxia, often with hearing impairment, is a common clinical presentation of superficial siderosis. Patients may develop myelopathy, here being a pure sensory myelopathy with predominant dorsal column deficit. Meningeal diverticulae and superficial siderosis are both associated with cerebrospinal fluid (CSF) leaks. This patient had dural ectasia and meningeal diverticulae, but the CT myelogram found no CSF leak. Superficial siderosis should be considered in patients with sensory myelopathy. Lumbosacral dural ectasia, or less likely CSF leak, can cause superficial siderosis in people with Marfan syndrome.

Background Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) and multiple sclerosis (MS) have both overlapping and distinct MRI lesion features, which vary with imaging timing. This study identified distinguishing MRI characteristics using paired MRIs at clinical attack and remission. Methods We retrospectively identified Mayo Clinic patients with MOGAD and MS that: (1) fulfilled respective diagnostic criteria; (2) had paired attack (≤30 days) and remission MRI scans (≥12 months) without interval attacks. MRIs were compared between groups for key features. Results We included 43 patients with MOGAD (median age 31 years (range, 3–67); 63% female) and 49 patients with MS (median age 39 years (range, 17–65); 65% female). Resolution of at least one T2-lesion differentiated MOGAD from MS (sensitivity, (95% CI 77% to 100%), specificity, (95% CI 86% to 99%); Youden’s index (YI)=0.90). Resolution of at least two T2-lesions indicated MOGAD (sensitivity 62% (95% CI 41% to 79%); specificity, 100% (95% CI 94% to 100%); YI=0.62). MOGAD patients were more likely to have normal MRI scans at follow-up compared with MS (brain 14/44 (32%) vs 0/60 (0%), p<0.001; spine 21/27 (78%) vs 7/36 (19%), p<0.001). In addition, the presence of T1-hypointense, ovoid periventricular T2, and enhancing lesions were more common in MS versus MOGAD at attack and remission and in the spine, longitudinally extensive T2 lesions were more common in MOGAD attacks (8/27 (30%)). Conclusion Paired MRI at attack and remission revealed distinctive characteristics of MOGAD and MS, with greater diagnostic value at remission driven by the discriminating power of T2-lesion resolution. In MOGAD patients with initial parenchymal involvement, a 1-year follow-up MRI may aid diagnosis and serve as a new baseline.

Photon-counting computed tomography (PCCT) is a new imaging technology that has advanced diagnostic imaging by offering improved spatial and contrast resolution as well as novel spectral imaging capabilities. Unlike conventional CT, which uses energy-integrating detectors, PCCT employs photon-counting detectors that directly measure individual photon energies, enabling applications such as virtual monochromatic imaging (VMI) and material decomposition. These innovations allow for artifact reduction, better visualization of fine anatomic structures, and improved diagnostic accuracy, all while reducing radiation dose. This review explores select applications of PCCT in neuroimaging, focusing on the brain, temporal bone, and spine. In the brain, we discuss how PCCT demonstrates superior performance for evaluating aneurysms, metallic prostheses, and vessel stenosis, offering enhanced visualization of vascular structures and minimizing artifacts. For temporal bone imaging, we review assessment of both complex anatomy and potentially subtle pathologies such as otosclerosis, as well as visualization of implants like cochlear devices and their intricate components. In spinal imaging, we explore how PCCT improves precise detection of causes of cerebrospinal fluid leaks, improves localization of tiny vessels such as the artery of Adamkiewicz and spinal dural arteriovenous fistulas, and reduces metal artifacts associated with postoperative hardware. PCCT addresses limitations of conventional CT while unlocking new diagnostic possibilities across neuroimaging applications. As clinical adoption of PCCT grows, ongoing research and development will refine imaging protocols and expand its utility. The accumulating evidence underscores PCCT’s transformative potential to improve diagnostic confidence in neuroimaging and beyond.

CSF-venous fistulas (CVFs) are a common cause of spontaneous intracranial hypotension. These fistulas usually occur without any preceding major trauma, surgery, or other iatrogenic cause. Occasionally, patients have a history of minor trauma, though such cases are usually still considered spontaneous. Little is known about predisposing factors that cause patients to develop spontaneous CVFs. Most patients with CVFs have multiple meningeal diverticula on spine imaging, and fistulas usually arise in association with a diverticulum. In the vast majority of cases, the culprit diverticulum from which the CVF arises is atraumatic in origin, presumably on the spectrum of normal variation in spinal anatomy. Here, we present two cases of CVFs that arose in association with posttraumatic pseudomeningoceles. To our knowledge, this phenomenon has not yet been reported, and it potentially represents a novel etiology for CVFs that furthers understanding of their pathogenesis.