Predicting High-Flow Spinal CSF Leaks in Spontaneous Intracranial Hypotension Using a Spinal MRI-Based Algorithm: Have Repeat CT Myelograms Been Reduced?

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.

Co-existing fast CSF leaks and CSF-venous fistulas on dynamic CT myelography

Spontaneous intracranial hypotension can be caused by spinal dural tears or CSF-venous fistulas. It is rare for patients to have more than one type of leak at any given time. Here, we illustrate 3 examples of dural tears that co-existed with CSF-venous fistulas, with both being seen on dynamic CT myelography. To our knowledge, coexistent CSF-venous fistulas and dural tears have not been previously illustrated on dynamic CT myelography, even though this is one of the most commonly used modalities to work-up patients with CSF leaks. We discuss the clinical importance of the rare co-occurrence of these leaks with regard to diagnosis and treatment, as well as implications for understanding and classifying CSF leaks.

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.

Cerebrospinal fluid leaks secondary to dural tears: a review of etiology, clinical evaluation, and management

OBJECTIVE

Damage to the dura mater often occurs in trauma cases of the head and spine, surgical procedures, lumbar punctures, and meningeal diseases. The resulting damage from dural tears, or durotomy, causes cerebrospinal fluid (CSF) to leak out into the surrounding space. The CSF leak induces intracranial hypotension, which can clinically present with a range of symptoms not limited to positional headaches which can confound accurate diagnosis. Current methods of evaluation and management of dural tears are discussed herewith, as well as the present understanding of its etiology, which may be classified as related to surgery, procedure, trauma, or connective tissue disorder.

METHODS

We piloted a MEDLINE® database search of literature, with emphasis on the previous five years, combining keywords such as "cerebrospinal fluid leak," "surgery," "procedure," and "trauma" to yield original research articles and case reports for building a clinical profile.

RESULTS

Patients with suspected dural tears should be evaluated based on criteria set by the International Headache Society, radiological findings, and a differential diagnosis to accurately identify the tear and its potential secondary complications. Afflicted patients may be treated promptly with epidural blood patches, epidural infusions, epidural fibrin glue, or surgical repair. At this time, epidural blood patches are the first line of treatment. Dural tears can be prevented to an extent by utilizing minimally invasive techniques and certain positions for lumbar puncture. Surgical, trauma, lumbar puncture, and epidural injection patients should be observed very carefully for dural tears and CSF leaks as the presenting clinical manifestations can be highly individualized and misguiding.

CONCLUSION

Because studies have demonstrated a high frequency of dural tears, particularly in spinal surgery patients, there is a need for prospective studies so that clinicians can develop an elaborate prevention strategy and response to avoid serious, unseen complications.

Spontaneous Intracranial Hypotension: A Systematic Imaging Approach for CSF Leak Localization and Management Based on MRI and Digital Subtraction Myelography

BACKGROUND AND PURPOSE

Localization of the culprit CSF leak in patients with spontaneous intracranial hypotension can be difficult and is inconsistently achieved. We present a high yield systematic imaging strategy using brain and spine MRI combined with digital subtraction myelography for CSF leak localization.

MATERIALS AND METHODS

During a 2-year period, patients with spontaneous intracranial hypotension at our institution underwent MR imaging to determine the presence or absence of a spinal longitudinal extradural collection. Digital subtraction myelography was then performed in patients positive for spinal longitudinal extradural CSF collection primarily in the prone position and in patients negative for spinal longitudinal extradural CSF collection in the lateral decubitus positions.

RESULTS

Thirty-one consecutive patients with spontaneous intracranial hypotension were included. The site of CSF leakage was definitively located in 27 (87%). Of these, 21 were positive for spinal longitudinal extradural CSF collection and categorized as having a ventral (type 1, fifteen [48%]) or lateral dural tear (type 2; four [13%]). Ten patients were negative for spinal longitudinal extradural CSF collection and were categorized as having a CSF-venous fistula (type 3, seven [23%]) or distal nerve root sleeve leak (type 4, one [3%]). The locations of leakage of 2 patients positive for spinal longitudinal extradural CSF collection remain undefined due to resolution of spontaneous intracranial hypotension before repeat digital subtraction myelography. In 2 (7%) patients negative for spinal longitudinal extradural CSF collection, the site of leakage could not be localized. Nine of 21 (43%) patients positive for spinal longitudinal extradural CSF collection were treated successfully with an epidural blood patch, and 12 required an operation. Of the 10 patients negative for spinal longitudinal extradural CSF collection (8 localized), none were effectively treated with an epidural blood patch, and all have undergone (n = 7) or are awaiting (n = 1) an operation.

CONCLUSIONS

Patients positive for spinal longitudinal extradural CSF collection are best positioned prone for digital subtraction myelography and may warrant additional attempts at a directed epidural blood patch. Patients negative for spinal longitudinal extradural CSF collection are best evaluated in the decubitus positions to reveal a CSF-venous fistula, common in this population. Patients with CSF-venous fistula may forgo further epidural blood patch treatment and go on to surgical repair.

Spontaneous Intracranial Hypotension: Imaging in Diagnosis and Treatment

This article reviews the role of imaging in the diagnosis, management, and treatment of spontaneous intracranial hypotension (SIH). SIH is a debilitating and often misdiagnosed condition caused by either a spinal cerebrospinal fluid (CSF) leak or a CSF to venous fistula. This pathologic condition is identified and localized via spinal imaging, including computed tomographic (CT) myelography, dynamic myelography, dynamic (ultrafast) CT myelography, MR imaging, or MR myelography with intrathecal gadolinium. Treatment of SIH involves conservative measures, surgery, or imaging-guided epidural blood patching.

Spontaneous Intracranial Hypotension: 10 Myths and Misperceptions

OBJECTIVE

To discuss common myths and misperceptions about spontaneous intracranial hypotension (SIH), focusing on common issues related to diagnosis and treatment, and to review the evidence that contradicts and clarifies these myths.

BACKGROUND

Recognition of SIH has increased in recent years. With increasing recognition, however, has come an increased demand for management by neurologists and headache specialists, some of whom have little prior experience with the condition. This dearth of practical experience, and lack of awareness of recent investigations into SIH, produces heterogeneity in diagnostic and treatment pathways, driven in part by outdated, confusing, or unsubstantiated conceptions of the condition. We sought to address this heterogeneity by identifying 10 myths and misperceptions that we frequently encounter when receiving referrals for suspected or confirmed SIH, and to review the literature addressing these topics.

METHODS

Ten topics relevant to diagnosis and treatment SIH were generated by the authors. A search for studies addressing SIH was conducted using PubMed and EMBASE, limited to English language only, peer reviewed publications from inception to 2018. Individual case reports were excluded. The resulting studies were reviewed for relevance to the topics in question.

RESULTS

The search generated 557 studies addressing SIH; 75 case reports were excluded. Fifty-four studies were considered to be of high relevance to the topics addressed, and were included in the data synthesis. The topics are presented in the form of a narrative review.

CONCLUSIONS

The understanding of SIH has evolved over the recent decades, leading to improvements in knowledge about the pathophysiology of the condition, diagnostic strategies, and expanded treatments. Awareness of these changes, and dispelling outdated misconceptions about SIH, is critical to providing appropriate care for patients and guiding future investigations going forward.

Application of time-spatial labeling inversion pulse magnetic resonance imaging in the diagnosis of spontaneous intracranial hypotension due to high-flow cerebrospinal fluid leakage at C1-2

BACKGROUND

Spontaneous intracranial hypotension (SIH) due to cerebrospinal fluid (CSF) leakage at C1-2 poses diagnostic and therapeutic challenges to spine surgeons. Although computed tomography (CT) myelography has been the diagnostic imaging modality of choice for identifying the CSF leakage point, extradural CSF collection at C1-2 on conventional CT myelography or magnetic resonance imaging (MRI) may often be a false localizing sign.

CASE DESCRIPTION

The present study reports the successful application of time-spatial labeling inversion pulse (T-SLIP) MRI, which enabled the precise identification of the CSF leakage point at C1-2 in a 28-year-old woman with intractable SIH. After identifying the leakage point using both CT myelography and T-SLIP MRI, surgery was performed to seal the CSF leak. Intraoperatively, a pouch suggestive of an extradural arachnoid cyst around the left C2 nerve root was found, which was repaired by packing the pouch with muscle and fibrin glue. Clinical improvement was observed shortly after surgery, and postoperative imaging revealed the disappearance of the CSF leakage.

CONCLUSIONS

T-SLIP MRI may provide useful information on the flow dynamics of CSF in SIH patients due to high-flow leakage. However, further experience is required to assess its sensitivity and specificity as an imaging modality for identifying CSF leakage points.

Uncommon Manifestations of Intervertebral Disk Pathologic Conditions

Beyond the familiar disk herniations with typical clinical features, intervertebral disk pathologic conditions can have a wide spectrum of imaging and clinical manifestations. The goal of this review is to illustrate and discuss unusual manifestations of intervertebral disk pathologic conditions that radiologists may encounter, including disk herniations in unusual locations, those with atypical imaging features, and those with uncommon pathophysiologic findings. Examples of atypical disk herniations presented include dorsal epidural, intradural, symptomatic thoracic (including giant calcified), extreme lateral (retroperitoneal), fluorine 18 fluorodeoxyglucose-avid, acute intravertebral (Schmorl node), and massive lumbar disk herniations. Examples of atypical pathophysiologic conditions covered are discal cysts, fibrocartilaginous emboli to the spinal cord, tiny calcified disks or disk-level spiculated osteophytes causing spinal cerebrospinal fluid (CSF) leak and intracranial hypotension, and pediatric acute calcific discitis. This broad gamut of disease includes a variety of sizes of disk pathologic conditions, from the tiny (eg, the minuscule calcified disks causing high-flow CSF leaks) to the extremely large (eg, giant calcified thoracic intradural disk herniations causing myelopathy). A spectrum of clinical acuity is represented, from hyperacute fibrocartilaginous emboli causing spinal cord infarct, to acute Schmorl nodes, to chronic intradural herniations. The entities included are characterized by a range of clinical courses, from the typically devastating cord infarct caused by fibrocartilaginous emboli, to the usually spontaneously resolving pediatric acute calcific discitis. Several conditions have important differential diagnostic considerations, and others have relatively diagnostic imaging findings. The pathophysiologic findings are well understood for some of these entities and poorly defined for others. Radiologists' knowledge of this broad scope of unusual disk disease is critical for accurate radiologic diagnoses. Online supplemental material is available for this article. (©)RSNA, 2016.