Role of Conventional Dynamic Myelography for Detection of High-Flow Cerebrospinal Fluid Leaks

Myelographic Techniques for the Localization of CSF-Venous Fistulas: Updates in 2024

CSF-venous fistulas (CVFs) are a common cause of spontaneous intracranial hypotension. Despite their relatively frequent occurrence, they can be exceedingly difficult to detect on imaging. Since the initial description of CVFs in 2014, the recognition and diagnosis of this type of CSF leak has continually increased. As a result of multi-institutional efforts, a wide spectrum of imaging modalities and specialized techniques for CVF detection is now available. It is important for radiologists to be familiar with the multitude of available techniques, because each has unique advantages and drawbacks. In this article, we review the spectrum of imaging modalities available for the detection of CVFs, explain the advantages and disadvantages of each, provide typical imaging examples, and discuss provocative maneuvers that may improve the conspicuity of CVFs. Discussed modalities include conventional CT myelography, dynamic myelography, digital subtraction myelography, conebeam CT myelography, decubitus CT myelography by using conventional energy-integrating detector scanners, decubitus photon counting CT myelography, and intrathecal gadolinium MR myelography. Additional topics to be discussed include optimal patient positioning, respiratory techniques, and intrathecal pressure augmentation.

Microsurgical Repair of Ventral Cerebrospinal Fluid Leaks in Spontaneous Intracranial Hypotension: Efficacy and Safety of Patch-Sealing Versus Suturing

BACKGROUND AND OBJECTIVES

In patients with spontaneous intracranial hypotension (SIH), microsurgical repair is recommended in Type 1 (ventral) dural leaks, when conservative measures fail. However, there is lacking consensus on the optimal surgical technique for permanent and safe closure of ventral leaks.

METHODS

We performed a retrospective analysis of surgically treated SIH patients with Type 1 leaks at our institution between 2013 and 2023. Patients were analyzed according to the type of surgical technique: (1) Microsurgical suture vs (2) extradural and intradural patching (sealing technique). End points were resolution of spinal longitudinal epidural cerebrospinal fluid collection (SLEC), change in brain SIH-Score (Bern-Score), headache resolution after 3 months, surgery time, complications, and reoperation rates.

RESULTS

In total, 85 (66% women) patients with consecutive SIH (mean age 47 ± 11 years) underwent transdural microsurgical repair. The leak was sutured in 53 (62%) patients (suture group) and patch-sealed in 32 (38%) patients (sealing group). We found no significant difference in the rates of residual SLEC and resolution of headache between suture and sealing groups (13% vs 22%, P = .238 and 89% vs 94%, P = .508). No changes were found in the postoperative Bern-Score between suture and sealing groups (1.4 [±1.6] vs 1.7 [±2.1] P = 1). Mean surgery time was significantly shorter in the sealing group than in the suture group (139 ± 48 vs 169 ± 51 minutes; P = .007). Ten patients of the suture and 3 of the sealing group had a complication (23% vs 9%, P = .212), whereas 6 patients of the suture and 2 patients of the sealing group required reoperation (11% vs 6%, P = .438).

CONCLUSION

Microsurgical suturing and patch-sealing of ventral dural leaks in patients with SIH are equally effective. Sealing alone is a significantly faster technique, requiring less spinal cord manipulation and may therefore minimize the risk of surgical complications.

CSF-venous leak responsible for spontaneous intracranial hypotension treated by endovascular venous route: First cases in Italy

Spontaneous intracranial hypotension (SIH) is due to a leakage of CSF lowering the pressure of subarachnoid space, mostly caused by a dural breach or discogenic microspur. Clinical and MRI are usually typical enough to allow diagnosis, while finding the location of the dural breach is challenging. Since some years, CSF venous fistulas have been described as the cause of SIH, and a specific diagnostic and therapeutic path has been proposed. Here we report the first two successfully treated patients in Italy. Both had chronic and non specific symptoms, with severe reduction of quality of life; clinical symptoms improved after endovascular occlusion of the responsible vein.

Surgical closure of spinal cerebrospinal fluid leaks improves symptoms in patients with superficial siderosis

BACKGROUND AND PURPOSE

Spinal cerebrospinal fluid (CSF) leaks may cause a myriad of symptoms, most common being orthostatic headache. In addition, ventral spinal CSF leaks are a possible etiology of superficial siderosis (SS), a rare condition characterized by hemosiderin deposits in the central nervous system (CNS). The classical presentation of SS involves ataxia, bilateral hearing loss, and myelopathy. Unfortunately, treatment options are scarce. This study was undertaken to evaluate whether microsurgical closure of CSF leaks can prevent further clinical deterioration or improve symptoms of SS.

METHODS

This cohort study was conducted using data from a prospectively maintained database in two large spontaneous intracranial hypotension (SIH) referral centers in Germany and Switzerland of patients who meet the modified International Classification of Headache Disorders, 3rd edition criteria for SIH. Patients with spinal CSF leaks were screened for the presence of idiopathic infratentorial symmetric SS of the CNS.

RESULTS

Twelve patients were included. The median latency between the onset of orthostatic headaches and symptoms attributed to SS was 9.5 years. After surgical closure of the underlying spinal CSF leak, symptoms attributed to SS improved in seven patients and remained stable in three. Patients who presented within 1 year after the onset of SS symptoms improved, but those who presented in 8-12 years did not improve. We could show a significant association between patients with spinal longitudinal extrathecal collections and SS.

CONCLUSIONS

Long-standing untreated ventral spinal CSF leaks can lead to SS of the CNS, and microsurgical sealing of spinal CSF leaks might stop progression and improve symptoms in patients with SS in a time-dependent manner.

Distinct Pattern of Membrane Formation With Spinal Cerebrospinal Fluid Leaks in Spontaneous Intracranial Hypotension

BACKGROUND AND OBJECTIVES

To systematically describe pertinent, intraoperative anatomic findings encountered when approaching spinal cerebrospinal fluid (CSF) leaks and CSF-venous fistulas in spontaneous intracranial hypotension (SIH).

METHODS

In a retrospective study, we included surgically treated patients suffering from SIH at our institution from April 2018 to March 2022. Anatomic, intraoperative data were extracted from operative notes and supplemented with data from surgical videos and images. Prominent anatomic features were compared among different types of CSF leaks.

RESULTS

The study cohort consists of 120 patients with a mean age of 45.2 years. We found four distinct patterns of spinal membranes specifically associated with different types of CSF leaks: (i) thick, dorsal membranes, which were hypervascular and may mimic the dura (pseudodura); (ii) thin, lateral membranes encapsulating a ventral epidural CSF compartment (confining the spinal longitudinal extradural CSF collection); (iii) ventral membranes constituting a transdural funnel-like CSF channel; and (iv) lateral membranes forming spinal cysts/meningeal diverticulae associated with lateral CSF leaks. The latter three types resemble a layer of arachnoid herniated through the dural defect.

CONCLUSION

We describe four distinct spinal (neo-)membranes in association with spinal CSF leaks. Formation of these membranes, or emergence by herniation of arachnoid through a dural defect, constitutes a specific pathoanatomic feature of patients with SIH and CSF leaks. Recognition of these membranes is of paramount importance for diagnosis and treatment of patients with spinal CSF leaks.

A technique to localize posteriorly located spinal dural leaks associated with spontaneous intracranial hypotension: Dorsal-decubitus dynamic CT myelography

BACKGROUND

Precise localization and understanding of the origin of cerebrospinal fluid (CSF) leak is crucial to allow targeted treatment. We report the technical feasibility and utility of dorsal-decubitus dynamic computed tomography (DDDCT) myelography to localize posteriorly located dural defects in patients with suspicion of posterolateral dural tears.

METHODS

This study reports a series of four consecutive patients with posteriorly located SLEC and suspicion of posterolateral CSF leak who received DDDCT to localize the site of the leak. Patients were collected between October 2022 and October 2023. The technique of DDDCT and its efficacy to detect the site of CSF leak are reported.

RESULTS

In all four patients (three females, one male, mean age 39 years), DDDCT myelography was technically successful and precisely demonstrated the site of the CSF leak. In one patient with both anterior and posterior SLEC, DDDCT allowed to exclude the presence of a posteriorly located leak, while a subsequent ventral decubitus dynamic CT myelography localized the leak. Leak sites were all thoracic, except for one that was cervical. Information obtained from the DDDCT myelography was considered useful to target the treatment of the leak.

CONCLUSIONS

Based on our experience, DDDCT provided sufficient spatial and temporal resolution to pinpoint fast CSF leaks and it may be considered to localize posterolateral dural defects.

Diagnosis and surgical therapy of spontaneous intracranial hypotension

Spontaneous intracranial hypotension (SIH) is a serious medical condition caused by loss of cerebrospinal fluid at the level of the spine, which, when not treated, may cause substantial long-term disability and increase morbidity. The following video summarizes the necessary steps for successful diagnosis and treatment of SIH, starting with a brain and spine magnetic resonance imaging, followed by dynamic myelography. Because an epidural bloodpatch did not provide a lasting relief, the patient underwent surgery which demonstrated a ventral dural slit caused by an osteodiscogenic microspur. In the 1-month follow up, the patient was symptom free. This video is meant to raise awareness of SIH among clinicians in order to increase general sensitivity for this diagnosis.

Conebeam CT as an Additional Tool in Digital Subtraction Myelography for the Detection of Spinal Lateral Dural Tears

Lateral dural tears as a cause spontaneous intracranial hypotension occur in ∼20% of patients. Common imaging modalities for their detection are lateral decubitus digital subtraction myelography or dynamic CT myelography. Reports on the use of conebeam CT are scarce. We show 3 patients in whom the targeted use of conebeam CT during digital subtraction myelography was helpful in confirming the site of the leak.

Overview of Spontaneous Intracranial Hypotension and Differential Diagnosis with Chiari I Malformation

Spontaneous intracranial hypotension (SIH) occurs due to a leakage of the cerebrospinal fluid (CSF) lowering the pressure of subarachnoid space, mostly caused by a dural breach or discogenic microspur. As a result of less support provided by CSF pressure, intracranial structures are stretched downward, leading to a constellation of more or less typical MRI findings, including venous congestion, subdural effusions, brainstem sagging and low-lying cerebellar tonsils. Clinic examination and an MRI are usually enough to allow for the diagnosis; however, finding the location of the dural tear is challenging. SIH shares some MRI features with Chiari malformation type I (CM1), especially low-lying cerebellar tonsils. Since SIH is likely underdiagnosed, these findings could be interpreted as signs of CM1, leading to a misdiagnosis and an incorrect treatment pathway. Medical treatment, including steroids, bed rest, hydration caffeine, and a blind epidural blood patch, have been used in this condition with variable success rates. For some years, CSF venous fistulas have been described as the cause of SIH, and a specific diagnostic and therapeutic pathway have been proposed. The current literature on SIH with a focus on diagnosis, treatment, and differential diagnosis with CM1, is reviewed and discussed.

Intraoperative Visualization of Flow in Direct Cerebrospinal Fluid-Venous Fistulas Using Intrathecal Fluorescein

BACKGROUND

Cerebrospinal fluid-venous fistulas (CVFs) are a rare cause of spontaneous intracranial hypotension. Intraoperatively, CVFs are not readily identifiable and difficult to differentiate from normal veins.

OBJECTIVE

To assess the utility of intrathecal fluorescein injection intraoperatively to visualize and identify the CVF.

METHODS

We report a case series of patients treated surgically for a CVF. After surgical exposure, we injected intrathecal fluorescein (5-10 mg) through a lumbar catheter, which we placed immediately before surgery.

RESULTS

Four patients with spontaneous intracranial hypotension with a suspected CVF underwent surgical ligation with adjunctive intrathecal fluorescein application. Intraoperative fluorescein injection confirmed the presence of a CVF in 3 cases. In 2 cases, we observed rapid fluorescein filling of a single epidural vein constituting the CVF. Other epidural vessels did not fill with fluorescein. In 1 case, fluorescein helped to identify a residual CVF after previous incomplete embolization. In the fourth case, no CVF was found intraoperatively. By contrast, a meningeal nerve root diverticulum was visualized, wrapped, and clipped.

CONCLUSION

We demonstrate for the first time the direct intraoperative visualization of CVF using intrathecal fluorescein. CVF can be identified intraoperatively using fluorescein dye, which can be a valuable adjunct for the surgeon confronted with this disease.

Epidural Blood Patching in Spontaneous Intracranial Hypotension-Do we Really Seal the Leak?

PURPOSE

Epidural blood patch (EBP) is a minimally invasive treatment for spontaneous intracranial hypotension (SIH). Follow-up after EBP primarily relies on clinical presentation and data demonstrating successful sealing of the underlying spinal cerebrospinal fluid (CSF) leak are lacking. Our aim was to evaluate the rate of successfully sealed spinal CSF leaks in SIH patients after non-targeted EBP.

METHODS

Patients with SIH and a confirmed spinal CSF leak who had been treated with non-targeted EBP were retrospectively analyzed. Primary outcome was persistence of CSF leak on spine MRI or intraoperatively. Secondary outcome was change in clinical symptoms after EBP.

RESULTS

In this study 51 SIH patients (mean age, 47 ± 13 years; 33/51, 65% female) treated with non-targeted EBP (mean, 1.3 EBPs per person; range, 1-4) were analyzed. Overall, 36/51 (71%) patients had a persistent spinal CSF leak after EBP on postinterventional imaging and/or intraoperatively. In a best-case scenario accounting for missing data, the success rate of sealing a spinal CSF leak with an EBP was 29%. Complete or substantial symptom improvement in the short term was reported in 45/51 (88%), and in the long term in 17/51 (33%) patients.

CONCLUSION

Non-targeted EBP is an effective symptomatic treatment providing short-term relief in a substantial number of SIH patients; however, successful sealing of the underlying spinal CSF leak by EBP is rare, which might explain the high rate of delayed symptom recurrence. The potentially irreversible and severe morbidity associated with long-standing intracranial hypotension supports permanent closure of the leak.

Modified Dynamic CT Myelography for Type 1 and 2 CSF Leaks: A Procedural Approach

BACKGROUND AND PURPOSE

Dynamic CT myelography can identify spinal CSF leaks secondary to dural tears (type 1) and ruptured meningeal diverticula (type 2), but the radiation can be high secondary to multiple successive acquisitions. The purpose of this article is to discuss the procedural approach of a modified dynamic CT myelography technique with single scan acquisitions, reduced contrast volume, and condensed scan coverage and compare its radiation dose with that in traditional dynamic CT myelography.

MATERIALS AND METHODS

Retrospective review was performed for patients with spontaneous CSF leaks showing extradural collections on spine MR imaging who underwent traditional and modified dynamic CT myelography. The radiation doses between the 2 cohorts were compared.

RESULTS

Thirty-seven patients (25 women, 12 men) had a type 1 or 2 CSF leak on dynamic CT myelography. Thirty-one patients had a type 1 CSF leak, and 6 patients had type 2 leaks. The traditional dynamic CT myelography was performed in 25 patients, and the average number of acquisitions per dynamic CT myelography was 3.6. The mean total effective dose per dynamic CT myelography was 31.3 mSv (range, 11.3-68.4 mSv). The modified dynamic CT myelography was performed in 12 patients, and the average number of acquisitions was 2.8. The mean total effective dose per dynamic CT myelography was 15.1 mSv (range, 4.8-24.6 mSv). The effective dose and dose-length product between the cohorts were statistically significant (P  < .0001 and .01, respectively).

CONCLUSIONS

Modified dynamic CT myelography performed with single scan acquisitions, smaller volume of contrast, and reduced scan coverage can reduce the radiation dose for type 1 and 2 CSF leak detection.

The "Crossing Collection Sign": A Diagnostic Tool on Spine Magnetic Resonance Imaging For Localizing Cerebrospinal Fluid Leak

OBJECTIVE

The aim of the study is to determine whether the site of "cross" between ventral and dorsal spinal longitudinal extradural CSF collections (SLECs) seen on magnetic resonance imaging during initial workup of patients with suspected CSF leaks can predict the subsequently confirmed leakage site on computed tomography myelography or surgical repair.

METHODS

This was an institutional review board-approved, retrospective study performed from 2006 to 2021. Patients with SLECs who underwent total spine magnetic resonance imaging at our institution, followed by myelography and/or surgical repair for CSF leak, were included. Patients with incomplete workup including lack of computed tomography myelography and/or surgical repair and patients severely motion degraded imaging were excluded from our study. The site of cross between ventral and dorsal SLECs was defined as the "crossing collection sign" and was compared with the anatomically confirmed site of leak on myelography and/or at surgical repair.

RESULTS

Thirthy-eight patients met inclusion criteria with 18 females and 11 males ranging in age from 27 to 60 years (median, 40 years; interquartile range, 14 years). The crossing collection sign was seen in 76% of patients (n = 29). The distributions of confirmed CSF leak were as follows: cervical (n = 9), thoracic (n = 17), and lumbar spine (n = 3). The crossing collection sign predicted the site of CSF leak in 14 of 29 patients (48%) and was within 3-vertebral segments in 26 of 29 cases (90%).

CONCLUSIONS

The crossing collection sign can help prospectively identify spinal regions with highest likelihood for CSF leak in patients with SLECs. This can potentially help optimize the more invasive subsequent steps in the workup for these patients, including dynamic myelography and surgical exploration for repair.

Minimally invasive surgery for spinal cerebrospinal fluid leaks in spontaneous intracranial hypotension

OBJECTIVE

Spinal CSF leaks cause spontaneous intracranial hypotension (SIH). Surgical closure of spinal CSF leaks is the treatment of choice for persisting leaks. Surgical approaches vary, and there are no studies in which minimally invasive techniques were used. In this study, the authors aimed to detail the safety and feasibility of minimally invasive microsurgical sealing of spinal CSF leaks using nonexpandable tubular retractors.

METHODS

Consecutive patients with SIH and a confirmed spinal CSF leak treated at a single institution between April 2019 and December 2020 were included in the study. Surgery was performed via a dorsal 2.5-cm skin incision using nonexpandable tubular retractors and a tailored interlaminar fenestration and, if needed, a transdural approach. The primary outcome was successful sealing of the dura, and the secondary outcome was the occurrence of complications.

RESULTS

Fifty-eight patients, 65.5% of whom were female (median age 46 years [IQR 36-55 years]), with 38 ventral leaks, 17 lateral leaks, and 2 CSF venous fistulas were included. In 56 (96.6%) patients, the leak could be closed, and in 2 (3.4%) patients the leak was missed because of misinterpretation of the imaging studies. One of these patients underwent successful reoperation, and the other patient decided to undergo surgery at another institution. Two other patients had to undergo reoperation because of insufficient closure and a persisting leak. The rate of permanent neurological deficit was 1.7%, the revision rate for a persisting or recurring leak was 3.4%, and the overall revision rate was 10.3%. The rate of successful sealing during the primary closure attempt was 96.6% and 3.4% patients needed a secondary attempt. Clinical short-term outcome at discharge was unchanged in 14 patients and improved in 25 patients, and 19 patients had signs of rebound intracranial hypertension.

CONCLUSIONS

Minimally invasive surgery with tubular retractors and a tailored interlaminar fenestration and, if needed, a transdural approach is safe and effective for the treatment of spinal CSF leaks. The authors suggest performing a minimally invasive closure of spinal CSF leaks in specialized centers.

Imaging, Clinical, and Demographic Differences in Patients With Type III Spinal Cerebrospinal Fluid Leak (Cerebrospinal Venous Fistulas) Compared With Patients With Types I and II Spinal Cerebrospinal Fluid Leak

OBJECTIVE

Spinal cerebrospinal fluid (CSF) leaks are an underdiagnosed cause of neurologic symptoms. The most common types of spinal CSF leaks are from dural tears (type I) and meningeal diverticula (type II). Cerebrospinal fluid-venous fistulas (type III) are less common and underrecognized. The purpose of this study was to evaluate the intracranial and spinal imaging findings in patients with types I/II versus type III leaks.

MATERIALS AND METHODS

This was a retrospective, institutional review board-approved study performed on adult patients between January 2020 to September 2021 with surgically confirmed type I/II/III spinal CSF leak. Patients had preoperative brain magnetic resonance imaging (MRI) with contrast and medical records detailing symptoms and clinical diagnoses. Patients were excluded for nondiagnostic brain MRIs. Demographic and clinical information were recorded. The presence of extra-axial collections, pachymeningeal thickening, brain sagging, and decreased pontomamillary distance were evaluated on MRI.

RESULTS

Seven patients had type III leaks, and 16 had type I/II leaks. Patients with type III leaks were older (P = 0.0003) and had higher rates of initial misdiagnosis (100% vs 31%) and longer times to correct diagnosis (P = 0.03) compared with type I/II leaks. Intracranial extra-axial collections were never seen with type III leaks but were seen in 50% of type I/II leaks. Pachymeningeal thickening and brainstem sagging occurred in nearly equal frequency between groups. Smaller pontomamillary distances were seen in type III leaks versus type I/II leaks (P = 0.047).

CONCLUSIONS

When evaluating patients with suspected spinal CSF leak, findings of older age, absence of intracranial extra-axial collections, and small pontomamillary distances may raise suspicion for type III versus type I/II leak.

T2-Sampling Perfection With Application-Optimized Contrasts by Using Flip Angle Evolution (SPACE) Protocol MRI: A Safe, Minimally Invasive Screening Tool for Spinal CSF Leak Causing Spontaneous Intracranial Hypotension

Spontaneous intracranial hypotension (SIH) due to a spinal cerebrospinal fluid (CSF) leak is secondary cause of headache with potentially devastating consequences. Its diagnosis is complicated owing to the lack of a reasonable, minimally invasive screening test. This results in many patients remaining undiagnosed for years after the headache onset. Current testing approaches are either overly invasive, namely the CSF infusion protocol or both invasive and insensitive viz. lumbar puncture (LP) with an opening pressure (OP) or computed tomography myelogram (CTM). These diagnostic methods are frequently employed in a clinical setting since they require access to the thecal space; they unfortunately have a dearth of sensitivity. CTM will not document a leak if it is intermittent or very slow and in the setting of a spinal CSF leak, the OP on LP may be high, low, or normal. A potential remedy for this state is the T2-sampling perfection with application-optimized contrasts by using flip angle evolution (SPACE) protocol spinal magnetic resonance imaging (MRI). We present two cases that demonstrate its potential value as a screening tool. It is well known for its high sensitivity for identifying spinal pathology and is minimally invasive, making it a good choice for a screening modality when diagnosing possible SIH cases.

Lateral decubitus dynamic CT myelography for fast cerebrospinal fluid leak localization

Dynamic CT myelography is used to precisely localize fast spinal CSF leaks. The procedure is most commonly performed in the prone position, which successfully localizes most fast ventral leaks. We have recently encountered a small subset of patients in whom prone dynamic CT myelography is unsuccessful in localizing leaks. We sought to determine the added value of lateral decubitus dynamic CT myelography, which is occasionally attempted in our practice, in localizing the leak after failed prone dynamic CT myelography. We retrospectively identified 6 patients who underwent lateral decubitus dynamic CT myelography, which was performed in each case because their prone dynamic CT myelogram was unrevealing. Two neuroradiologists independently reviewed preprocedural spine MRI and all dynamic CT myelograms for each patient. Lateral decubitus positioning allowed for precise leak localization in all 6 patients. Five of six patients were noted to have dorsal and/or lateral epidural fluid collections on spine MRI. One patient had a single prominent diverticulum on spine MRI (larger than 6 mm), whereas the others had no prominent diverticula. Our study suggests that institutions performing dynamic CT myelography to localize fast leaks should consider a lateral decubitus study if performing the study in the prone position is unrevealing. Furthermore, the presence of dorsal and/or lateral epidural fluid collections on spine MRI may suggest that a lateral decubitus study is of higher yield and could be considered initially.

Minimally invasive surgery for spinal cerebrospinal fluid-venous fistula ligation: patient series

BACKGROUND

Cerebrospinal fluid-venous fistulas (CVFs) may cause cerebrospinal fluid leaks resulting in spontaneous intracranial hypotension (SIH). Surgical treatment of CVFs aims to eliminate abnormal fistulous connections between the subarachnoid space and the epidural venous plexus at the level of the nerve root sleeve. The authors propose a percutaneous minimally invasive technique for surgical ligation of CVF as an alternative to the traditional open approach using a tubular retractor system.

OBSERVATIONS

Minimally invasive surgical (MIS) ligation of spinal CVF was performed in 5 patients for 6 CVFs. The definite disconnection of the CVF was achieved in all patients by clipping and additional silk tie ligation of the fistula. None of the patients experienced surgical complications or required transition to an open procedure. One patient underwent 2 MIS procedures for 2 separate CVFs. Postoperative clinical follow-up and cranial magnetic resonance imaging confirmed resolution of symptoms and radiographic SIH stigmata.

LESSONS

MIS ligation of CVFs is safe and efficient. It represents an elegant and less invasive procedure, reducing the risk of wound infections and time to recovery. However, preparedness for open ligation is warranted within the same surgical setting in cases of complications and difficult accessibility.

Same-Day Bilateral Decubitus CT Myelography for Detecting CSF-Venous Fistulas in Spontaneous Intracranial Hypotension

Lateral decubitus CT myelography is a sensitive technique for detecting CSF-venous fistulas in patients with spontaneous intracranial hypotension. It might be necessary to perform bilateral studies to locate a fistula. We report on the feasibility of obtaining diagnostic-quality bilateral decubitus CT myelography in a single session, avoiding the need to schedule separate examinations for the left and right sides on different days.

Spontaneous intracranial hypotension: the role of radiology in diagnosis and management

Spontaneous intracranial hypotension (SIH) is a condition that results from leakage of cerebrospinal fluid (CSF) from the spine, and which typically presents with debilitating orthostatic headache, but can be associated with a wide range of other symptoms. The causes of spontaneous CSF leaks that lead to SIH include dural tears, leaking meningeal diverticula, and CSF-venous fistulas. Imaging plays a central role in the initial diagnosis of SIH and in its subsequent investigation and management. This article reviews the typical neuroimaging manifestations of SIH and discusses the utility of different myelographic techniques for localising spinal CSF leaks as well as the role of image-guided treatment.

Spontaneous intracranial hypotension: diagnostic and therapeutic workup

Spontaneous intracranial hypotension (SIH) is an orthostatic headache syndrome with typical MRI findings among which engorgement of the venous sinuses, pachymeningeal enhancement, and effacement of the suprasellar cistern have the highest diagnostic sensitivity. SIH is in almost all cases caused by spinal CSF leaks. Spinal MRI scans showing so-called spinal longitudinal extradural fluid (SLEC) are suggestive of ventral dural tears (type 1 leak) which are located with prone dynamic (digital subtraction) myelography. As around half of the ventral dural tears are located in the upper thoracic spine, additional prone dynamic CT myelography is often needed. Leaking nerve root sleeves typically associated with meningeal diverticulae (type 2 leaks) and CSF-venous fistulas (type 3 leaks) are proven via lateral decubitus dynamic digital subtraction or CT myelography: type 2 leaks are SLEC-positive if the tear is proximal and SLEC-negative if it is distal, and type 3 leaks are always SLEC-negative. Although 30–70% of SIH patients show marked improvement following epidural blood patches applied via various techniques definite cure mostly requires surgical closure of ventral dural tears and surgical ligations of leaking nerve root sleeves associated with meningeal diverticulae or CSF-venous fistulas. For the latter, transvenous embolization with liquid embolic agents via the azygos vein system is a novel and valuable therapeutic alternative.

Outcome after surgical treatment of cerebrospinal fluid leaks in spontaneous intracranial hypotension-a matter of time

Objective

Spinal cerebrospinal fluid (CSF) leaks cause spontaneous intracranial hypotension (SIH). Microsurgery can sufficiently seal spinal CSF leaks. Yet, some patients suffer from residual symptoms. Aim of the study was to assess predictors for favorable outcome after surgical treatment of SIH.

Methods

We included consecutive patients with SIH treated surgically from January 2013 to May 2020. Subjects were surveyed by a questionnaire. Primary outcome was resolution of symptoms as rated by the patient. Secondary outcome was postoperative headache intensity on the numeric rating scale (NRS). Association between variables and outcome was assessed using univariate and multivariate regression. A cut-off value for continuous variables was calculated by a ROC analysis.

Results

Sixty-nine out of 86 patients (80.2%) returned the questionnaire and were analyzed. Mean age was 46.7 years and 68.1% were female. A significant association with the primary and secondary outcome was found only for preoperative symptom duration (p = 0.001 and p < 0.001), whereby a shorter symptom duration was associated with a better outcome. Symptom duration remained a significant predictor in a multivariate model (p = 0.013). Neither sex, age, type of pathology, lumbar opening pressure, nor initial presentation were associated with the primary outcome. ROC analysis yielded treatment within 12 weeks as a cut-off for better outcome.

Conclusion

Shorter duration of preoperative symptoms is the most powerful predictor of favorable outcome after surgical treatment of SIH. While an initial attempt of conservative treatment is justified, we advocate early definitive treatment within 12 weeks in case of persisting symptoms.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-021-10710-7.

CSF-Venous Fistulas: Anatomy and Diagnostic Imaging

CSF-venous fistulas (CVFs), first described in 2014, represent an important cause of spontaneous intracranial hypotension (SIH). CVFs can be challenging to detect on conventional anatomic imaging because, unlike other types of spinal CSF leak, they do not typically result in pooling of fluid in the epidural space, and imaging signs of CVF may be subtle. Specialized myelographic techniques have been developed to help with CVF identification, but these techniques are not yet widely disseminated. This article reviews the current understanding of CVFs, emphasizing correlations between venous anatomy and imaging findings as well as potential mechanisms for pathogenesis, and describes current imaging techniques used for CVF diagnosis and localization. These techniques are broadly classified into fluoroscopy-based methods, including digital subtraction myelography and dynamic myelography, as well as cross-sectional methods, including decubitus CT myelography and MR myelography with intrathecal gadolinium. Knowledge of these various options, including their relative advantages and disadvantages, is critical in the care of patients with SIH. Investigation is ongoing, and continued advances are anticipated in understanding of CVFs as well as in optimal imaging detection.