Is foramen magnum decompression for acquired Chiari I malformation like putting a finger in the dyke? - A simplistic overview of artificial intelligence in assessing critical upstream and downstream etiologies.

Background: Missed diagnosis of evolving or coexisting idiopathic (IIH) and spontaneous intracranial hypotension (SIH) is often the reason for persistent or worsening symptoms after foramen magnum decompression for Chiari malformation (CM) I. We explore the role of artificial intelligence (AI)/convolutional neural networks (CNN) in Chiari I malformation in a combinatorial role for the first time in literature, exploring both upstream and downstream magnetic resonance findings as initial screening profilers in CM-1. We have also put together a review of all existing subtypes of CM and discuss the role of upright (gravity-aided) magnetic resonance imaging (MRI) in evaluating equivocal tonsillar descent on a lying-down MRI. We have formulated a workflow algorithm MaChiP 1.0 (Manjila Chiari Protocol 1.0) using upstream and downstream profilers, that cause de novo or worsening Chiari I malformation, which we plan to implement using AI. Materials and Methods: The PRISMA guidelines were used for "CM and machine learning and CNN" on PubMed database articles, and four articles specific to the topic were encountered. The radiologic criteria for IIH and SIH were applied from neurosurgical literature, and they were applied between primary and secondary (acquired) Chiari I malformations. An upstream etiology such as IIH or SIH and an isolated downstream etiology in the spine were characterized using the existing body of literature. We propose the utility of using four selected criteria for IIH and SIH each, over MRI T2 images of the brain and spine, predominantly sagittal sequences in upstream etiology in the brain and multiplanar MRI in spinal lesions. Results: Using MaChiP 1.0 (patent/ copyright pending) concepts, we have proposed the upstream and downstream profilers implicated in progressive Chiari I malformation. The upstream profilers included findings of brain sagging, slope of the third ventricular floor, pontomesencephalic angle, mamillopontine distance, lateral ventricular angle, internal cerebral vein-vein of Galen angle, and displacement of iter, clivus length, tonsillar descent, etc., suggestive of SIH. The IIH features noted in upstream pathologies were posterior flattening of globe of the eye, partial empty sella, optic nerve sheath distortion, and optic nerve tortuosity in MRI. The downstream etiologies involved spinal cerebrospinal fluid (CSF) leak from dural tear, meningeal diverticula, CSF-venous fistulae, etc. Conclusion: AI would help offer predictive analysis along the spectrum of upstream and downstream etiologies, ensuring safety and efficacy in treating secondary (acquired) Chiari I malformation, especially with coexisting IIH and SIH. The MaChiP 1.0 algorithm can help document worsening of a previously diagnosed CM-1 and find the exact etiology of a secondary CM-I. However, the role of posterior fossa morphometry and cine-flow MRI data for intracranial CSF flow dynamics, along with advanced spinal CSF studies using dynamic myelo-CT scanning in the formation of secondary CM-I is still being evaluated.

Cranial and Spinal Cerebrospinal Fluid Leaks: Foundations of Identification and Management.

Cerebrospinal fluid (CSF) leaks may occur at the skull base or along the spinal column and can cause a variety of debilitating neurological symptoms for patients. Recognizing the potential presence of a CSF leak and then identifying its source are necessary for accurate diagnosis and definitive treatment. A standardized workflow can be followed for successful leak localization, which often requires several diagnostic studies, and for definitive leak treatment, which can range from minimally invasive, needle-based approaches to a variety of surgical corrections. This review paper provides an overview of epidemiology, pathophysiology, and diagnostic workup for CSF leaks and introduces available treatment options. An illustrative case of a skull base CSF leak demonstrating diagnosis and surgical correction is provided.

Spinal dementia: Don't miss it, it's treatable.

BACKGROUND & PURPOSE: Around 5% of dementia patients have a treatable cause. To estimate the prevalence of two rare diseases, in which the treatable cause is at the spinal level. METHODS: A radiology information system was searched using the terms CT myelography and the operation and classification system (OPS) code 3-241. The clinical charts of these patients were reviewed to identify patients with a significant cognitive decline. RESULTS: Among 205 patients with spontaneous intracranial hypotension (SIH) and proven CSF leaks we identified five patients with a so-called frontotemporal brain sagging syndrome: Four of those had CSF venous fistulas and significantly improved by occluding them either by surgery or transvenous embolization. Another 11 patients had infratentorial hemosiderosis and hearing problems and ataxia as guiding symptoms. Some cognitive decline was present in at least two of them. Ten patients had ventral dural tears in the thoracic spine and one patient a lateral dural tear at C2/3 respectively. Eight patients showed some improvement after surgery. DISCUSSION: It is mandatory to study the (thoracic) spine in cognitively impaired patients with brain sagging and/ or infratentorial hemosiderosis on MRI. We propose the term spinal dementia to draw attention to this region, which in turn is evaluated with dynamic digital subtraction and CT myelography.

A Severe Case of Spontaneous Intracranial Hypotension in an Adult Asian Male Improved With Trendelenburg Positioning: A Case Report.

Non-traumatic bilateral acute subdural hematomas are a rare occurrence. Etiologies typically include, but are not limited to, cortical artery bleeding, vascular lesions, coagulopathies, and spontaneous intracranial hypotension. We report a case of a 45-year-old Korean male with no known co-morbid illnesses nor history of head or neck trauma, who came to the emergency department due to a 10-day history of dizziness and head heaviness, followed by disorientation and drowsiness. The patient was diagnosed with bilateral acute subdural hematoma; hence, a bilateral posterior parietal craniotomy with evacuation of hematoma was performed. Neurologic status initially improved remarkably; however, during rehabilitation, there was recurrence of acute bilateral subdural hematoma requiring repeat surgical evacuation. There was no clinical improvement after the repeat surgery, and his condition further deteriorated in the neurosciences critical care unit showing signs of rostrocaudal deterioration at the level of diencephalon. A plain cranial CT scan was performed, which showed central herniation and "brain sagging." A diagnosis of spontaneous intracranial hypotension was considered; thus, the patient was managed by positioning him in the Trendelenburg position alternating with flat position on the bed. A search for the cerebrospinal fluid leak was commenced by performing a whole spine MRI constructive interference in steady state (CISS) protocol, which showed a longitudinal spinal anterior epidural cerebrospinal fluid leak from spinal level C2 to T1. Radionuclide cisternography did not provide definitive scintigraphic evidence of a leak. The patient gradually improved and was eventually transferred out of the neurosciences critical care unit. After days of rehabilitation in the hospital, the patient was discharged ambulatory with minimal support.

Improvement of health-related quality of life after closure of spinal CSF leaks in patients with spontaneous intracranial hypotension.

OBJECTIVE: Spontaneous intracranial hypotension (SIH) is an important cause of orthostatic headaches caused by spinal CSF leaks. It has a strong negative impact on patients' socioeconomic status and health-related quality of life (HRQOL). This study aimed to analyze the impact of surgical and endovascular treatments on patients' HRQOL. METHODS: The authors conducted a prospective, observational cohort study that included all patients treated for SIH with microsurgery or embolization, depending on the type of CSF leak, at their institution between April 2022 and May 2023. Patients were asked to complete a specifically designed questionnaire, as well as the 15D HRQOL questionnaire, before and 3 months after treatment. RESULTS: A total of 21 patients (14 female; mean age 51.7 years) were treated in the study period. There were 12 (57%) type 1 leaks, 3 (14%) type 2, and 6 (29%) type 3. While 20 (95.2%) leaks were localized in the thoracic spine, only 1 (4.8%) was found in the lumbar spine. All patients completed the questionnaires. Fifteen (71.4%) patients underwent microsurgery and 6 (28.6%) endovascular embolization. The mean 15D score improved from 0.802 before to 0.889 after treatment (p = 0.013). Compared with an age- and sex-matched general population, HRQOL was significantly impaired in patients with SIH before treatment. After treatment, the authors found no significant difference in the overall HRQOL between patients and the healthy population. Mean headache intensity on a numeric rating scale improved from 8.1 before treatment to 2.3 after treatment (p = 0.003). Patients reported that SIH had a notable impact on their social and working life. CONCLUSIONS: SIH has a considerable negative impact on HRQOL. Microsurgery or embolization can dramatically improve HRQOL, subjective perception of health, and headache intensity. Therefore, surgical or endovascular treatment should be considered given the improvement observed in HRQOL for patients with SIH.

A Low-Volume Epidural Blood Patch for the Treatment of Spontaneous Intracranial Hypotension: A Case Report.

Spontaneous intracranial hypotension (SIH) is a rare neurological syndrome. We report the case of a 47-year-old woman with acute, severe orthostatic headache after surgery, chemotherapy, and radiotherapy for breast cancer. The brain and spine magnetic resonance imaging showed signs of intracranial hypotension. We describe the results of a non-targeted epidural blood patch with 10 mL of the patient's blood administered after unsuccessful conservative treatment. After the procedure, the patient reported gradual headache relief. This effect persisted over one year. The case shows that a single non-targeted low-volume epidural blood patch can be an effective treatment option for a patient with SIH when conservative treatment fails.

Spontaneous Intracranial Hypotension: Case Report and Update on Diagnosis and Treatment.

Spontaneous intracranial hypotension (SIH) is an important cause of daily headaches that occur in young and middle-aged, active persons and is often misdiagnosed, leading to prolonged inactivity and rather high healthcare expenditures. Its diagnosis requires a high degree of clinical suspicion and careful interpretation of imaging studies. We present a case of SIH, which was successfully treated but which posed serious diagnostic challenges, ranging from cerebro-vascular disease and meningitis to granulomatous diseases, and for whom every therapeutic attempt just worsened the patient's condition until we finally reached the correct diagnosis. To raise awareness of this condition, we also present an updated overview of the clinical picture, evaluation, and treatment options for SIH.

The Pressure of Headache at the United Kingdom CSF Disorders Day 2023.

Headache in intracranial disorders drives significant disability in our patients. Management principles for secondary headaches require a multidisciplinary approach with expertise from the neurological, neuro-ophthalmological, neuroradiological, and neurosurgical specialities. The Pressure of Headache was the theme of the annual United Kingdom CSF Disorders Day and saw speakers and panellists from Australia, Europe, and the United States. Among the topics presented were the newest concepts underpinning idiopathic intracranial hypertension management and spontaneous intracranial hypotension. Advances in our knowledge of cerebrospinal fluid secretion and the visual snow syndrome debate were particular highlights. This review provides a summary of the research on headache disorders that overlap the neuro-ophthalmological axis of care for patients.

Cerebrospinal Fluid-Venous Fistulas.

Cerebrospinal fluid-venous fistulas (CSFVFs) were first described in 2014 and have since become an increasingly diagnosed cause of spontaneous intracranial hypotension due to increased clinical recognition and advancements in diagnostic modalities. In this review, the authors discuss CSFVF epidemiology, the variety of clinical presentations, the authors' preferred diagnostic approach, recent advancements in diagnostic methods, treatment options, current challenges, and directions of future research.

Comparing 2-dimensional versus 3-dimensional MR myelography for cerebrospinal fluid leak detection.

Purpose: We compared cerebrospinal fluid (CSF) leak conspicuity and image quality as visualized using 3D versus 2D magnetic resonance (MR) myelography in patients with spinal CSF leaks. Methods: Eighteen patients underwent spinal MR imaging at 3 Tesla. Three board-certified radiologists independently evaluated CSF leak conspicuity and image quality on a 4-point scale; the latter assessed by scoring fat suppression, venous visualization, and severity of CSF flow artifacts. Additionally, the evaluators ranked the overall performances of 2D versus 3D MR myelography upon completing side-by-side comparisons of CSF leak conspicuity. Inter-reader agreement was determined using the Gwet's AC1. Results: The quality of 3D MR myelography images was significantly better than that of 2D MR myelography with respect to CSF leak conspicuity (mean scores: 3.3 vs. 1.9, p < 0.0001) and severity of CSF flow artifacts on the axial view (mean scores: 1.0 vs. 2.5, p = 0.0001). Inter-reader agreement was moderate to almost perfect for 2D MR myelography (AC1 = 0.55-1.00), and almost perfect for 3D MR myelography (AC1 = 0.85-1.00). Moreover, 3D MR myelography was judged to be superior to 2D acquisition in 78 %, 83 %, and 83 % of the samples per readers 1, 2 and 3, respectively; the inter-reader agreement was almost perfect (AC1: reader 1 vs. 2; 0.98, reader 2 vs. 3; 0.96, reader 3 vs. 1; 0.98). Conclusion: CSF leaks are more conspicuous when using 3D MR myelography than when using its 2D counterpart; therefore, the former is more reliable for identifying such leaks.

Spontaneous intracranial hypotension: Exploring the viability of non-contrast FLAIR as a substitute for contrast-enhanced T1WI in assessing pachymeningeal thickening.

PURPOSE: To avoid contrast administration in spontaneous intracranial hypotension (SIH), some studies suggest accepting diffuse pachymeningeal hyperintensity (DPMH) on non-contrast fluid-attenuated inversion recovery (FLAIR) as an equivalent sign to diffuse pachymeningeal enhancement (DPME) on contrast-enhanced T1WI (T1ce), despite lacking thorough performance metrics. This study aimed to comprehensively explore its feasibility. METHODS: In this single-center retrospective study, between April 2021 and November 2023, brain MRI examinations of 43 patients clinically diagnosed with SIH were assessed using 1.5 and 3.0 Tesla MRI scanners. Two radiologists independently assessed the presence or absence of DPMH on FLAIR and DPME on T1ce, with T1ce serving as a gold-standard for pachymeningeal thickening. The contribution of the subdural fluid collections to DPMH was investigated with quantitative measurements. Using Cohen's kappa statistics, interobserver agreement was assessed. RESULTS: In 39 out of 43 patients (90.7%), pachymeningeal thickening was observed on T1ce. FLAIR sequence produced an accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of 72.1%, 71.8%, 75.0%, 96.6%, and 21.4% respectively, for determining pachymeningeal thickening. FLAIR identified pachymeningeal thickening in 28 cases; however, among these, 21 cases (75%) revealed that the pachymeningeal hyperintense signal was influenced by subdural fluid collections. False-negative rate for FLAIR was 28.2% (11/39). CONCLUSION: The lack of complete correlation between FLAIR and T1ce in identifying pachymeningeal thickening highlights the need for caution in removing contrast agent administration from the MRI protocol of SIH patients, as it reveals a major criterion (i.e., pachymeningeal enhancement) of Bern score.

Factors to predict recurrence after epidural blood patch in patients with spontaneous intracranial hypotension.

OBJECTIVES: This study aimed to identify predictors for the recurrence of spontaneous intracranial hypotension (SIH) after epidural blood patch (EBP). BACKGROUND: Epidural blood patch is the main treatment option for SIH; however, the characteristics of patients who experience relapse after successful EBP treatment for SIH remain understudied. METHODS: In this exploratory, retrospective, case-control study, we included 19 patients with SIH recurrence after EBP and 36 age- and sex-matched patients without recurrence from a single tertiary medical institution. We analyzed clinical characteristics, neuroimaging findings, and volume changes in intracranial structures after EBP treatment. Machine learning methods were utilized to predict the recurrence of SIH after EBP treatment. RESULTS: There were no significant differences in clinical features between the recurrence and no-recurrence groups. Among brain magnetic resonance imaging signs, diffuse pachymeningeal enhancement and cerebral venous dilatation were more prominent in the recurrence group than no-recurrence group after EBP (14/19 [73%] vs. eight of 36 [22%] patients, p = 0.001; 11/19 [57%] vs. seven of 36 [19%] patients, p = 0.010, respectively). The midbrain-pons angle decreased in the recurrence group compared to the no-recurrence group after EBP, at a mean (standard deviation [SD]) of -12.0 [16.7] vs. +1.8[18.3]° (p = 0.048). In volumetric analysis, volume changes after EBP were smaller in the recurrence group than in the no-recurrence group in intracranial cerebrospinal fluid (mean [SD] -11.6 [15.3] vs. +4.8 [17.1] mL, p = 0.001) and ventricles (mean [SD] +1.0 [2.0] vs. +2.0 [2.5] mL, p = 0.003). Notably, the random forest classifier indicated that the model constructed with brain volumetry was more accurate in discriminating SIH recurrence (area under the curve = 0.80 vs. 0.52). CONCLUSION: Our study suggests that volumetric analysis of intracranial structures may aid in predicting recurrence after EBP treatment in patients with SIH.

Safety and efficacy of transvenous embolization of cerebrospinal fluid-venous fistula in patients with spontaneous intracranial hypotension.

BACKGROUND: Transvenous embolization is a recent treatment strategy for cerebrospinal fluid-venous fistulas (CSFVF), which are associated with spontaneous intracranial hypotension (SIH). METHODS: Participants were selected from a prospective database on patients with CSFVF that received transvenous Onyx embolization. All patients underwent a brain magnetic resonance imaging (MRI) before and after embolization with MRI follow-up performed at least 3 months after treatment. Clinical and MRI results after treatment were described. RESULTS: Twenty-one consecutive patients (median age 63 years, IQR = 58-71; females: 15/21 = 71.5%) with 30 CSFVF were included. Most lesions were situated between T9 and L1 (19/30 = 63%), 70% were right-sided, and 38% of the patients had multiples fistulas. Embolization was successful in all cases. The mean MRI SIH score before and after treatment was 6 (±2.5) and 1.4 (±1.6), respectively (p < 0.0001). Twenty patients (90%) experienced improvement of their initial condition, of which 67% reported complete clinical recovery. The mean HIT-6 score decreased from 67 (±15) to 38 (±9) (p < 0.0001), the mean amount of monthly headache days from 23.5 (±10) and 3.2 (±6.6) (p < 0.0001), the visual assessment scale (VAS) for headache severity from 8 (±1.9) to 1.2 (±2) (p < 0.0001), and the mean VAS for perception quality of life improved from 2.6 (±2.5) to 8.6 (±1.8) (p < 0.0001). There were no major complications. The suspected rebound headache rate after treatment was 33%. CONCLUSION: Transvenous embolization of CSFVF allowed high rates of clinical improvement with no morbidity related to the treatment.

Effect of blind versus fluoroscopic guidance epidural blood patch in patients with intracranial hypotension.

Epidural blood patch (EBP)-the most effective treatment for intracranial hypotension (IH)-can be performed using the blind technique in the lateral position or under fluoroscopic guidance in the prone position. This study aimed to compare the effectiveness of EBP in patients with spontaneous intracranial hypotension (sIH) and iatrogenic intracranial hypotension (iIH) when performed with the blind technique in the lateral decubitus position or fluoroscopic guidance in the prone position. We reviewed IH patients who underwent EBP between January 2015 and September 2019 in a single hospital and divided them into two groups according to the type of IH. Of the 84 included patients, 36 had sIH and 48 had iIH. We compared the effectiveness of EBP using the two methods in each group. There was no significant difference in the effect of EBP between the patients with iIH (p > 0.05). For patients with sIH, fluoroscopic guidance in the prone position technique showed better improvement than the blind technique in the lateral decubitus position (p < 0.05). We observed similar outcomes after blind EBP versus fluoroscopic guidance EBP in patients with iIH. However, procedure-dependent differences were observed in patients with sIH. For patients with sIH, it would be effective to consider fluoroscopic EBP first. Further study is needed to investigate interactions between method of EBP and other factors that affect the effectiveness of EBP.

Case report: Simultaneous measurement of intracranial pressure and lumbar intrathecal pressure during epidural patch therapy for treating spontaneous intracranial hypotension syndrome. Spontaneous intracranial hypotension or spontaneous intraspinal hypovolume?

Objectives: Spontaneous intracranial hypotension (SIH) is frequently complicated by subacute subdural hematoma (SDH) and more rarely by bilateral thalamic ischemia. Here, we report a case of SIH-related SDH treated with three epidural patches (EPs), with follow-up of the intracranial pressure and lumbar intrathecal pressure. Methods: A 46-year-old man presented bilateral thalamic ischemia, then a growing SDH. After failure of urgent surgical evacuation, he underwent three saline EPs, two dynamic myelography examinations and one digital subtraction angiography-phlebography examination. However, because of no dural tear and no obstacle to the venous drainage of the vein of Galen, no therapeutic procedure was available, and the patient died. Results: The case exhibited a progressive increase in the transmission of lumbar intrathecal pressure to intracranial pressure during the three EPs. The EPs may have successfully treated the SIH, but the patient did not recover consciousness because of irreversible damage to both thalami. Conclusion: Clinicians should be aware of the bilateral thalamic ischemia picture that may be the presenting sign of SIH. Moreover, the key problem in the pathophysiology of SIH seems to be intraspinal and intracranial volumes rather than pressures. Therefore, intracranial hypotension syndrome might actually be an intraspinal hypovolume syndrome.

Spontaneous Intracranial Hypotension: Clinical Presentation, Diagnosis, and Treatment Strategies.

Spontaneous intracranial hypotension (SIH) typically presents as an acute orthostatic headache during an upright position, secondary to spinal cerebrospinal fluid leaks. New evidence indicates that a lumbar puncture may not be essential for diagnosing every patient with SIH. Spinal neuroimaging protocols used for diagnosing and localizing spinal cerebrospinal fluid leaks include brain/spinal MRI, computed tomography myelography, digital subtraction myelography, and radionuclide cisternography. Complications of SIH include subdural hematoma, cerebral venous thrombosis, and superficial siderosis. Treatment options encompass conservative management, epidural blood patches, and surgical interventions. The early application of epidural blood patches in all patients with SIH is suggested.

Progressive superficial siderosis despite complete remission of intracranial hypotension symptoms following epidural patching: Case report.

Spontaneous intracranial hypotension (SIH) commonly results from ventral spinal cerebrospinal fluid (CSF) leaks and epidural patches are advocated as first-line treatment. Complications such as superficial siderosis can arise but have previously been reported only in the context of long-term persistent, ongoing, CSF leak and SIH. We report a case of a patient with SIH from a ventral spinal CSF leak that was treated with epidural patching and experienced complete resolution of SIH. Four years later SIH symptoms recurred, and brain magnetic resonance imaging unexpectedly showed the interval accumulation of hemosiderin pigmentation on the cerebellum and brainstem during the period when the patient was without symptoms of SIH. This case uniquely demonstrates the progression of superficial siderosis despite the apparent resolution of SIH. Our findings suggest two divergent pathophysiological outcomes from spinal ventral dural tear: (1) CSF loss causing SIH; and (2) persistent low-level bleeding arising from the spinal dural tear leading to superficial siderosis. These divergent pathophysiologies had a discordant response to epidural patching. Epidural patching successfully treated the SIH but did not prevent the progression of superficial siderosis, indicating that some patients may require more than epidural patching despite symptom resolution. This case highlights the need for post-treatment monitoring protocols in patients with ventral spinal CSF leaks and SIH and raises important questions about the adequacy of epidural patching in certain SIH cases arising from ventral spinal CSF leak.

Non-invasive biomarkers for spontaneous intracranial hypotension (SIH) through phase-contrast MRI.

BACKGROUND AND OBJECTIVE: Spontaneous intracranial hypotension (SIH) is an underdiagnosed disease. To depict the accurate diagnosis can be demanding; especially the detection of CSF-venous fistulas poses many challenges. Potential dynamic biomarkers have been identified through non-invasive phase-contrast MRI in a limited subset of SIH patients with evidence of spinal longitudinal extradural collection. This study aimed to explore these biomarkers related to spinal cord motion and CSF velocities in a broader SIH cohort. METHODS: A retrospective, monocentric pooled-data analysis was conducted of patients suspected to suffer from SIH who underwent phase-contrast MRI for spinal cord and CSF velocity measurements at segment C2/C3 referred to a tertiary center between February 2022 and June 2023. Velocity ranges (mm/s), total displacement (mm), and further derivatives were assessed and compared to data from the database of 70 healthy controls. RESULTS: In 117 patients, a leak was located (54% ventral leak, 20% lateral leak, 20% CSF-venous fistulas, 6% sacral leaks). SIH patients showed larger spinal cord and CSF velocities than healthy controls: e.g., velocity range 7.6 ± 3 mm/s vs. 5.6 ± 1.4 mm/s, 56 ± 21 mm/s vs. 42 ± 10 mm/s, p < 0.001, respectively. Patients with lateral leaks and CSF-venous fistulas exhibited an exceptionally heightened level of spinal cord motion (e.g., velocity range 8.4 ± 3.3 mm/s; 8.2 ± 3.1 mm/s vs. 5.6 ± 1.4 mm/s, p < 0.001, respectively). CONCLUSION: Phase-contrast MRI might become a valuable tool for SIH diagnosis, especially in patients with CSF-venous fistulas without evidence of spinal extradural fluid collection.

"Empty Cyst Sign" Appearance of CSF-Venous Fistula on Digital Spinal Myelography.

Cerebrospinal fluid venous fistulas (CSF-VFs) are an uncommon, yet increasingly recognized, cause of spontaneous intracranial hypotension.1-5 The workup involves magnetic resonance imaging (MRI) of the brain with and without contrast and MRI of the neuroaxis without contrast before dynamic myelography, either computed tomography or digital subtraction.6 The present case of an older woman with symptomatic intracranial hypotension is notable for the specific appearance of CSF-VFs on digital spinal myelography (Video 1). Among her numerous perineural cysts, it was the "disappearing" or "empty" cyst from which the fistula originated. The diagnosis was made using a second lateral fluoroscopy view, not typically used in digital spinal myelography, which demonstrated emptying of contrast from the T6 perineural cyst into the segmental vein at this level, or the "empty cyst sign." The patient then underwent transvenous onyx embolization with resolution of her orthostatic headaches and improvement of contrast-enhanced MRI of the brain with the Bern score decreasing from 7 to 0 at 3 months of follow-up.7 Because transvenous embolization of CSF-VFs is a relatively new procedure, the long-term outcomes of the procedure are not yet known.

Intrathecal hematoma following epidural blood patch: An alternative mechanism to intrathecal puncture.

Intrathecal blood after a percutaneous epidural blood patch is a known complication, one that has been previously attributed to inadvertent needle tip position in the subarachnoid space. We present two cases with imaging confirmation of an alternative mechanism, one that includes blood transferring from the epidural space to the subarachnoid space through a pre-existing dural defect.