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

Standard Fluoroscopic and Computed Tomography-Guided Lumbar Punctures

Image-guided lumbar puncture (LP) remains an important part of the modern practice of neuroradiology. This review outlines the relevant anatomy, safety considerations, and techniques in performing fluoroscopic and computed tomography-guided LPs.

Prevalence of Spinal Meningeal Diverticula in Autosomal Dominant Polycystic Kidney Disease

BACKGROUND AND PURPOSE

Patients with autosomal dominant polycystic kidney disease (ADPKD) develop cysts in the kidneys, liver, spleen, pancreas, prostate, and arachnoid spaces. In addition, spinal meningeal diverticula have been reported. To determine whether spinal meningeal diverticula are associated with ADPKD, we compared their prevalence in subjects with ADPKD with a control cohort without ADPKD.

MATERIALS AND METHODS

Subjects with ADPKD and age- and sex-matched controls without ADPKD undergoing abdominal MRI from the midthorax to the pelvis from 2003 to 2023 were retrospectively evaluated for spinal meningeal diverticula by 4 blinded observers. The prevalence of spinal meningeal diverticula in ADPKD was compared with that in control subjects, using t tests and correlated with clinical and laboratory data and MR imaging features, including cyst volumes and cyst counts.

RESULTS

Identification of spinal meningeal diverticula in ADPKD (n = 285, median age, 47; interquartile range [IQR], 37-56 years; 54% female) and control (n = 285, median age, 47; IQR, 37-57 years; 54% female) subjects had high interobserver agreement (pairwise Cohen κ = 0.74). Spinal meningeal diverticula were observed in 145 of 285 (51%) subjects with ADPKD compared with 66 of 285 (23%) control subjects without ADPKD (P < .001). Spinal meningeal diverticula in ADPKD were more prevalent in women (98 of 153 [64%]) than men (47 of 132 [36%], P < .001). The mean number of spinal meningeal diverticula per affected subject with ADPKD was 3.6 ± 2.9 compared with 2.4 ± 1.9 in controls with cysts (P < .001). The median volume (IQR, 25%-75%) of spinal meningeal diverticula was 400 (IQR, 210-740) mm3 in those with ADPKD compared with 250 (IQR, 180-440) mm3 in controls (P < .001). The mean spinal meningeal diverticulum diameter was greater in the sacrum (7.3 [SD, 4.1] mm) compared with thoracic (5.4 [SD, 1.8] mm) and lumbar spine (5.8 [SD, 2.0] mm), (P < .001), suggesting that hydrostatic pressure contributed to enlargement.

CONCLUSIONS

ADPKD has a high prevalence of spinal meningeal diverticula, particularly in women.

"Flow Void Sign": Flow Artifact on T2-Weighted MRI Can Be an Indicator of Dural Defect Location in Ventral Type 1 Spinal CSF Leaks

Patients with spontaneous intracranial hypotension caused by type 1 dural defects typically have an epidural fluid collection on MRI. Still, the location of the defect is not usually readily identifiable on standard MRI sequences and can be at any point along the length of the collection. The most common location for type 1 leaks is ventral and, as such, these are most commonly associated with ventral predominant epidural fluid. Dynamic myelography (either digital subtraction myelography or dynamic CT myelography) is currently the standard of care for localizing the defect. We describe an imaging sign on T2-weighted images caused by CSF-flow egress at the site of the defect that may permit accurate prediction of the site of the CSF leak noninvasively. Importantly, this sign was only observed on 2D T2-weighted and STIR images and not on 3D acquisitions, which notably suppress artifacts. This has implications for optimal MRI spine protocol construction. This sign can be used to limit myelographic range, reduce radiation dose, and increase diagnostic confidence in dural defect location.

Spontaneous Intracranial Hypotension in Children: A Multi-Institutional Review of Spinal CSF Leaks Localized on Advanced Myelography

Spontaneous intracranial hypotension is an increasingly recognized syndrome caused by a spinal CSF leak, with most reported cases occurring in adults. The use of specialized or advanced myelography to localize spinal CSF leaks has evolved substantially in recent years, particularly since the initial description of CSF-venous fistulas in 2014. To our knowledge, no prior series have evaluated the use of specialized myelographic techniques to localize CSF leaks in children with spontaneous intracranial hypotension, likely because the disease is rare in this patient population. This issue may be compounded by a hesitation to perform invasive procedures in children. In this clinical report, we conducted a multi-institutional review of pediatric patients with spontaneous spinal CSF leaks localized using advanced myelographic techniques, such as prone and decubitus digital subtraction and CT myelography, as well as dynamic CT myelography. We report the clinical features of these patients, as well as imaging findings, types of leaks discovered, and method of treatment. We found that the primary types of spontaneous spinal CSF leaks that occur in adults, including dural tears and CSF fistulas, can be seen in children, too. Furthermore, we show that specialized myelographic techniques can successfully localize these leaks and facilitate effective targeted treatment.

Spinal CSF Leaks: The Neuroradiologist Transforming Care

Spinal CSF leak care has evolved during the past several years due to pivotal advances in its diagnosis and treatment. To the reader of the American Journal of Neuroradiology (AJNR), it has been impossible to miss the exponential increase in groundbreaking research on spinal CSF leaks and spontaneous intracranial hypotension (SIH). While many clinical specialties have contributed to these successes, the neuroradiologist has been instrumental in driving this transformation due to innovations in noninvasive imaging, novel myelographic techniques, and image-guided therapies. In this editorial, we will delve into the exciting advancements in spinal CSF leak diagnosis and treatment and celebrate the vital role of the neuroradiologist at the forefront of this revolution, with particular attention paid to CSF leak-related work published in the AJNR.

Lateral Spinal CSF Leaks in Patients with Spontaneous Intracranial Hypotension: Radiologic-Anatomic Study of Different Variants

BACKGROUND AND PURPOSE

Spinal CSF leaks cause spontaneous intracranial hypotension. Several types of leaks have been identified, and one of these types is the lateral dural tear. Performing myelography with the patient in the decubitus position allows precise characterization of these leaks. The purpose of the current study was to describe the different variants of spontaneous lateral CSF leaks.

MATERIALS AND METHODS

This retrospective cohort study included a consecutive group of patients with spontaneous intracranial hypotension and lateral CSF leaks who underwent digital subtraction myelography in the decubitus position and underwent surgery to repair the CSF leak between July 2018 and June 2023.

RESULTS

The mean age of the 53 patients (37 women and 16 men) was 35.5 years. Three different variants of lateral CSF leak could be identified. Forty-nine patients (92.5%) had a lateral dural tear associated with the nerve root sleeve. The dural tear was at the axilla of the nerve root sleeve in 36 patients (67.9%) and at the shoulder in 13 patients (24.5%). Four patients (7.5%) had a lateral dural tear at the level of the pedicle that was not associated with the nerve root sleeve. Findings on digital subtraction myelography were concordant with intraoperative findings in all patients. An extradural CSF collection was seen in all patients with a lateral dural tear associated with the nerve root sleeve but in only 2 of the 4 patients with the pedicular variant of a lateral dural tear.

CONCLUSIONS

We identified 3 variants of spontaneous lateral dural tears. Most lateral dural tears are associated with extradural CSF collections and arise from either the axilla (67.9%) or the shoulder (24.5%) of the nerve root sleeve. Lateral dural tears at the level of the pedicle (7.5%) not associated with the nerve root sleeve are uncommon and may require specialized imaging for their detection.

Long-Term Epidural Patching Outcomes and Predictors of Benefit in Patients With Suspected CSF Leak Nonconforming to ICHD-3 Criteria

BACKGROUND AND OBJECTIVES

Spinal CSF leaks lead to spontaneous intracranial hypotension (SIH). While International Classification of Headache Disorders, Third Edition (ICHD-3) criteria necessitate imaging confirmation or low opening pressure (OP) for SIH diagnosis, their sensitivity may be limited. We offered epidural blood patches (EBPs) to patients with symptoms suggestive of SIH, with and without a documented low OP or confirmed leak on imaging. This study evaluates the efficacy of this strategy.

METHODS

We conducted a prospective cohort study with a nested case-control design including all patients who presented to a tertiary headache clinic with clinical symptoms of SIH who completed study measures both before and after receiving an EBP between August 2016 and November 2018.

RESULTS

The mean duration of symptoms was 8.7 ± 8.1 years. Of 85 patients assessed, 69 did not meet ICHD-3 criteria for SIH. At an average of 521 days after the initial EBP, this ICHD-3-negative subgroup experienced significant improvements in Patient-Reported Outcomes Measurement Information System (PROMIS) Global Physical Health score of +3.3 (95% CI 1.5-5.1), PROMIS Global Mental Health score of +1.8 (95% CI 0.0-3.5), Headache Impact Test (HIT)-6 head pain score of -3.8 (95% CI -5.7 to -1.8), Neck Disability Index of -4.8 (95% CI -9.0 to -0.6) and PROMIS Fatigue of -2.3 (95% CI -4.1 to -0.6). Fifty-four percent of ICHD-3-negative patients achieved clinically meaningful improvements in PROMIS Global Physical Health and 45% in HIT-6 scores. Pain relief following lying flat prior to treatment was strongly associated with sustained clinically meaningful improvement in global physical health at an average of 521 days (odds ratio 1.39, 95% CI 1.1-1.79; p < 0.003). ICHD-3-positive patients showed high rates of response and previously unreported, treatable levels of fatigue and cognitive deficits.

DISCUSSION

Patients who did not conform to the ICHD-3 criteria for SIH showed moderate rates of sustained, clinically meaningful improvements in global physical health, global mental health, neck pain, fatigue, and head pain after EBP therapy. Pre-treatment improvement in head pain when flat was associated with later, sustained improvement after EBP therapy among patients who did not meet the ICHD-3 criteria.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that epidural blood patch is an effective treatment of suspected CSF leak not conforming to ICHD-3 criteria for SIH.

Benefits of Photon-Counting CT Myelography for Localization of Dural Tears in Spontaneous Intracranial Hypotension

Photon-counting CT is an increasingly used technology with numerous advantages over conventional energy-integrating detector CT. These include superior spatial resolution, high temporal resolution, and inherent spectral imaging capabilities. Recently, photon-counting CT myelography was described as an effective technique for the detection of CSF-venous fistulas, a common cause of spontaneous intracranial hypotension. It is likely that photon-counting CT myelography will also have advantages for the localization of dural tears, a separate type of spontaneous spinal CSF leak that requires different myelographic techniques for accurate localization. To our knowledge, prior studies on photon-counting CT myelography have been limited to techniques for detecting CSF-venous fistulas. In this technical report, we describe our technique and early experience with photon-counting CT myelography for the localization of dural tears.

Spinal Cerebrospinal Fluid Leak Localization with Dynamic Computed Tomography Myelography: Tips, Tricks, and Pitfalls

Locating spinal cerebrospinal fluid (CSF) leaks can be a diagnostic dilemma for clinicians and radiologists, as well as frustrating for patients. Dynamic computed tomography myelography (dCTM) has emerged as a valuable tool in localizing spinal CSF leaks, aiding in accurate diagnosis, and guiding appropriate management. This article aims to provide insights into the technique, tips, tricks, and potential pitfalls associated with dCTM for spinal CSF leak localization. By understanding the nuances of this procedure, clinicians can optimize the diagnostic process and improve patient outcomes.

[Spinal Presentation of Spontaneous Intracranial Hypotension]

Spontaneous intracranial hypotension (SIH), which generally presents as orthostatic headache, is increasingly being identified due to improved imaging technologies and heightened awareness. Many prior studies have reported the characteristic brain MRI findings of SIH. However, recently, focus has shifted to spinal MRI, as SIH is believed to be caused by leakage of cerebrospinal fluid from the spinal dural sac. Advanced techniques such as ultrafast CT myelography and digital subtraction myelography have emerged as useful technique to identify the site of cerebrospinal fluid leakage. In this review, we discuss the diagnosis, spinal MRI findings, imaging techniques, and treatment of SIH.

Updated ultrafast dynamic computed tomography myelography technique for cerebrospinal fluid leaks

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.

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.

Utility of Photon-Counting Detector CT Myelography for the Detection of CSF-Venous Fistulas

CSF-venous fistulas are an increasingly recognized type of CSF leak that can be particularly challenging to detect, even with recently improved imaging techniques. Currently, most institutions use decubitus digital subtraction myelography or dynamic CT myelography to localize CSF-venous fistulas. Photon-counting detector CT is a relatively recent advancement that has many theoretical benefits, including excellent spatial resolution, high temporal resolution, and spectral imaging capabilities. We describe 6 cases of CSF-venous fistulas detected on decubitus photon-counting detector CT myelography. In 5 of these cases, the CSF-venous fistula was previously occult on decubitus digital subtraction myelography or decubitus dynamic CT myelography using an energy-integrating detector system. All 6 cases exemplify the potential benefits of photon-counting detector CT myelography in identifying CSF-venous fistulas. We suggest that further implementation of this imaging technique will likely be valuable to improve the detection of fistulas that might otherwise be missed with currently used techniques.