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.

Diagnostic Performance of Renal Contrast Excretion on Early Phase CT Myelography in Spontaneous Intracranial Hypotension.

BACKGROUND AND PURPOSE: Early opacification of the renal collecting system during CT myelography (CTM) performed for the evaluation of Spontaneous Intracranial Hypotension (SIH) has been demonstrated in prior studies. However, these investigations often included CTMs scanned >30 minutes after intrathecal contrast injection, a longer delay than the myelographic techniques used in current practice. The purpose of this study was to determine whether renal contrast excretion (RCE) measured during this earlier time period (≤30 minutes) can discriminate patients with SIH from patients without SIH. MATERIALS AND METHODS: Single-center, retrospective cohort of consecutive patients presenting for evaluation of possible SIH between July 2021-May 2022. RCE was measured in both renal hila using standardized (5-15mm3) ROIs. ROC curves were constructed comparing RCE between patients with SIH to patients without SIH in the overall cohort, and within the subgroup of patients with negative myelograms. RESULTS: The study cohort included 190 subjects. Both unadjusted and adjusted models demonstrated a statistically significant increase in renal contrast density among patients with SIH compared to those without SIH (p-values ≤ 0.001). The ROC curve showed moderate discrimination between these groups (AUC 0.76). However, using clinically meaningful test criteria of sensitivity >90% or specificity >90%, the two corresponding threshold HU values resulted in low specificity of 31.3% and sensitivity of 50.8%. Subgroup analysis of patients with negative myelograms showed poorer performance in discriminating SIH+ from SIH- (AUC 0.62). In this subgroup, using similar test criteria of sensitivity >90% or specificity >90 resulted in low specificities and sensitivities, at 26.0% and 37.5% respectively. CONCLUSIONS: We found a statistically significant positive association between RCE and SIH diagnosis during early-phase CTM, however clinically useful thresholds based on cutoff values for renal HU resulted in poor sensitivities or specificities, with substantial false positives or false negatives, respectively. Thus, while we confirmed statistically significant differences in RCE in the ≤30 min time period, in keeping with prior investigations of more delayed time periods, overlap in renal attenuation values prevented the development of clinically useful threshold value for discriminating SIH+ from SIH-patients. ABBREVIATIONS: SIH = spontaneous intracranial hypotension; RCE = renal contrast excretion; CTM = CT myelography; CVF = CSF-venous fistula; ICHD-3 = international classification of headache disorders third edition; CKD = chronic kidney disease.

Patient experience of spontaneous intracranial hypotension (SIH): qualitative interviews for concept elicitation.

BACKGROUND & OBJECTIVES: Spontaneous intracranial hypotension (SIH) is an underdiagnosed and debilitating condition caused by a spinal cerebrospinal fluid (CSF) leak. Although SIH can lead to substantial morbidity and disability, little data exists about patients' perspectives. Without hearing directly from patients, our understanding of the full experience of having SIH is limited, as is our ability to identify and use appropriate patient-reported outcome measures (PROMs) within clinical care and research. The purpose of this study was to conduct qualitative interviews with confirmed SIH patients to fully describe their experiences and identify relevant concepts to measure. METHODS: Patients were recruited from an SIH specialty clinic at a large, U.S.-based healthcare center. Patients undergoing an initial consultation who were ≥ 18 years old, English-speaking, met the International Classification of Headache Disorders-3 criteria for SIH, and had a brain MRI with contrast that was positive for SIH were eligible to participate. During semi-structured qualitative interviews with a trained facilitator, participants were asked to describe their current SIH symptoms, how their experiences with SIH had changed over time, and the aspects of SIH that they found most bothersome. Analysts reviewed the data, created text summaries, and wrote analytic reports. RESULTS: Fifteen participants completed interviews. Common symptoms reported by patients included headache, tinnitus, ear fullness/pressure/pain, and neck or interscapular pain. Patients reported that their symptoms worsened over the course of their day and with activity. The most bothersome aspect of SIH was disruption to daily activities and limits to physical activities/exercise, which were severe. With regard to symptoms, the most bothersome and impactful included physical pain and discomfort (including headache), as well as fatigue. CONCLUSIONS: Patients reported a diverse set of symptoms that were attributed to SIH, with devastating impacts on functioning and high levels of disability. Researchers considering use of PROMs for SIH should consider inclusion of both symptom scales and aspects of functioning, and future work should focus on evaluating the validity of existing measures for this patient population using rigorous qualitative and quantitative methods in diverse samples. Additionally, these data can be used to assist clinicians in understanding the impacts of SIH on patients.

Enterothecal fistula as a rare cause of adult pneumocephalus and meningitis: a case report.

Background: Enterothecal fistulas are pathological connections between the gastrointestinal system and subarachnoid space. These rare fistulas occur mostly in pediatric patients with sacral developmental anomalies. They have yet to be characterized in an adult born without congenital developmental anomaly yet must remain on the differential diagnosis when all other causes of meningitis and pneumocephalus have been ruled out. Good outcomes rely on aggressive multidisciplinary medical and surgical care, which are reviewed in this manuscript. Case Description: A 25-year-old female with history of a sacral giant cell tumor resected via anterior transperitoneal approach followed by posterior L4-pelvis fusion presented with headaches and altered mental status. Imaging revealed that a portion of small bowel had migrated into her resection cavity and created an enterothecal fistula resulting in fecalith within the subarachnoid space and florid meningitis. The patient underwent a small bowel resection for fistula obliteration, and subsequently developed hydrocephalus requiring shunt placement and two suboccipital craniectomies for foramen magnum crowding. Ultimately, her wounds became infected requiring washouts and instrumentation removal. Despite a prolonged hospital course, she made significant recovery and at 10-month following presentation, she is awake, oriented, and able to participate in activities of daily living. Conclusions: This is the first case of meningitis secondary to enterothecal fistula in a patient without a previous congenital sacral anomaly. Operative intervention for fistula obliteration is the primary treatment and should be performed at a tertiary hospital with multidisciplinary capabilities. If recognized quickly and appropriately treated, there is a possibility of good neurological outcome.

Popping the balloon: Abrupt onset of a spinal CSF leak and spontaneous intracranial hypotension in idiopathic intracranial hypertension, a case report.

OBJECTIVES: Spontaneous intracranial hypotension (SIH) is a debilitating neurologic condition that is often thought of as separate from idiopathic intracranial hypertension (IIH). The unique case presented here details a spontaneous spinal cerebrospinal fluid (CSF) leak that developed abruptly following a CSF pressure elevating maneuver in a patient with pre-existing intracranial hypertension, raising the possibility of a causative link between the two conditions. RESULTS: A 40-year-old woman with symptomatic IIH developed a dural tear of a thoracic spinal nerve root sleeve during an episode of Valsalva maneuver leading to a CSF leak and development of symptomatic SIH. This was successfully treated with epidural blood and fibrin glue patch and the patient is now symptom-free. DISCUSSION: The implication of a possible causative link between elevated CSF pressure and subsequent development of dural rupture and SIH raises important questions regarding the pathophysiology of SIH in some cases. Furthermore, it suggests that there could be a potential prophylactic benefit of CSF pressure lowering medications in preventing the development of SIH in patients with IIH.

Digital manometry to measure cerebrospinal fluid pressure during lumbar puncture.

RATIONALE AND OBJECTIVES: Accurate cerebrospinal fluid (CSF) pressure measurements are critical for diagnosis and treatment of pathologic processes involving the central nervous system. Measuring opening CSF pressure using an analog device takes several minutes, which can be burdensome in a busy practice. The purpose of this study was to compare accuracy of a digital pressure measurement device with analog manometry, the reference gold standard. Secondary purpose included an assessment of possible time savings. MATERIALS AND METHODS: This study was a retrospective, cross-sectional investigation of 71 patients who underwent image-guided lumbar puncture (LP) with opening CSF pressure measurement at a single institution from June 2019 to September 2019. Exclusion criteria were examinations without complete data for both the digital and analog measurements or without recorded needle gauge. All included LPs and CSF pressures were measured with the patient in the left lateral decubitus position, legs extended. Acquired data included (1) digital and analog CSF pressures and (2) time required to measure CSF pressure. RESULTS: A total of 56 procedures were analyzed in 55 patients. There was no significant difference in mean CSF pressures between devices: 22.5 cm H2O digitally vs 23.1 analog (p = .7). Use of the digital manometer resulted in a time savings of 6 min (438 s analog vs 78 s digital, p < .001). CONCLUSION: Cerebrospinal fluid pressure measurements obtained with digital manometry demonstrate comparable accuracy to the reference standard of analog manometry, with an average time savings of approximately 6 min per case.

Differentiation of Chiari malformation type 1 and spontaneous intracranial hypotension using objective measurements of midbrain sagging.

OBJECTIVE: Chiari malformation type 1 (CM-1) and spontaneous intracranial hypotension (SIH) are causes of headache in which cerebellar tonsillar ectopia (TE) may be present. An accurate method for differentiating these conditions on imaging is needed to avoid diagnostic confusion. Here, the authors sought to determine whether objective measurements of midbrain morphology could distinguish CM-1 from SIH on brain MRI. METHODS: This is a retrospective case-control series comparing neuroimaging in consecutive adult subjects with CM-1 and SIH. Measurements obtained from brain MRI included previously reported measures of brain sagging: TE, slope of the third ventricular floor (3VF), pontomesencephalic angle (PMA), mamillopontine distance, lateral ventricular angle, internal cerebral vein-vein of Galen angle, and displacement of iter (DOI). Clivus length (CL), an indicator of posterior fossa size, was also measured. Measurements for the CM-1 group were compared to those for the entire SIH population (SIHall) as well as a subgroup of SIH patients with > 5 mm of TE (SIHTE subgroup). RESULTS: Highly significant differences were observed between SIHall and CM-1 groups in the following measures: TE (mean ± standard deviation, 3.1 ± 5.7 vs 9.3 ± 3.5 mm), 3VF (-16.8° ± 11.2° vs -2.1° ± 4.6°), PMA (44.8° ± 13.1° vs 62.7° ± 9.8°), DOI (0.2 ± 4.1 vs 3.8 ± 1.6 mm), and CL (38.3 ± 4.5 vs 44.0 ± 3.3 mm; all p < 0.0001). Eight (16%) of 50 SIH subjects had TE > 5 mm; in this subgroup (SIHTE), a cutoff value of < -15° for 3VF and < 45° for PMA perfectly discriminated SIH from CM-1 (sensitivity and specificity = 1.0). DOI showed perfect specificity (1.0) in detecting SIH among both groups. No subjects with SIH had isolated TE without other concurrent findings of midbrain sagging. CONCLUSIONS: Measures of midbrain sagging, including cutoff values for 3VF and PMA, discriminate CM-1 from SIH and may help to prevent misdiagnosis and unnecessary surgery.

CSF-Venous Fistulas: Anatomy and Diagnostic Imaging.

CSF-venous fistulas (CVFs), first described in 2014, are an important cause of spontaneous intracranial hypotension. 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, and cross-sectional methods, including decubitus CT myelography and MR myelography with intrathecal injection of gadolinium. Knowledge of these various options, including their relative advantages and disadvantages, is critical in the care of patients with spontaneous intracranial hypotension. Investigation is ongoing, and continued advances in knowledge about CVFs as well as in optimal imaging detection are anticipated.

Split cord malformation in adults: Literature review and classification.

The objective of this study was to summarize the available literature describing the presentation, diagnostic evaluation, and management for adults with Type 1 and Type 2 split spinal cord malformations. A review of the literature was performed using the CINAHL, PubMed, Embase, and Web of Science database, alongside all associated bibliographies, to include studies describing Type 1 and Type 2 split cord malformations diagnosed in patients above the age of 18. All relevant studies of split cord malformations were included, regardless of the year published and terminology used to describe the dysraphism. Clinical case series (≥ 2 patients), cohort studies, and review articles comprising adult patients with radiographically diagnosed diastematomyelia, diplomyelia, or dimyelia were included (Class of Evidence I-IV). A total of 17 unique articles, describing 146 unique adult spinal cord malformation subjects, were included. The most common associated condition was tethered cord syndrome (59.8 %). Operative management for symptomatic split cord malformation was performed in 72.3 % of cases. For those with preoperative neurologic deficits, operative management resulted in symptomatic improvement in 96.6 %, compared to 0 % conservative management (p < 0.05). For those with pain alone, operative management resulted in improvement of 91.1 %, compared to 12.5 % conservative management (p < 0.05). To date, this is the only literature review to include all split cord malformations (SCM Types I and II) presenting in adulthood, with clinical characteristics, associated conditions, and long-term treatment outcomes.

Clinical Outcomes Following Surgical Ligation of Cerebrospinal Fluid-Venous Fistula in Patients With Spontaneous Intracranial Hypotension: A Prospective Case Series.

BACKGROUND: Cerebrospinal fluid-venous fistula (CVF) is a recently described cause of spontaneous intracranial hypotension (SIH). Surgical ligation of CVF has been reported, but clinical outcomes are not well described. OBJECTIVE: To determine the clinical efficacy of surgical ligation for treatment of CVF. METHODS: Outcomes metrics were collected in this prospective, single-arm, cross-sectional investigation. Inclusion criteria were as follows: diagnosis of SIH, demonstration of CVF on myelography, and surgical treatment of CVF. Pre- and postoperative headache severity was assessed with the Headache Impact Test (HIT-6), a validated headache scale ranging from 36 (asymptomatic) to 78 (most severe). Patient satisfaction with treatment was measured with Patient Global Impression of Change (PGIC). RESULTS: Twenty subjects were enrolled, with mean postoperative follow-up at 16.0 ± 9.7 mo. All CVFs were located in the thoracic region (between T4 and T12). Pretreatment headache severity was high (mean HIT-6 scores 65 ± 6). Surgical treatment resulted in marked improvement in headache severity (mean HIT-6 change of -21 ± -9, mean postoperative HIT-6 of 44 ± 8). Of subjects with baseline headache scores in the most severe category, 83% showed a major improvement in severity (transition to the lowest 2 severity categories) after surgery. All subjects (100%) reported clinically significant levels of satisfaction with treatment (PGIC score 6 or 7); 90% reported the highest level of satisfaction. There were no short- or long-term complications or 30-d readmissions. CONCLUSION: Surgical ligation is highly effective for the treatment of SIH due to CVF. Larger controlled trials with longer follow-up period are indicated to better assess its long-term efficacy and safety profile.

Spontaneous Intracranial Hypotension: Pathogenesis, Diagnosis, and Treatment.

Spontaneous intracranial hypotension (SIH) is a clinical syndrome that is increasingly recognized as an important and treatable secondary cause of headaches. Insight into the condition has evolved significantly over the past decade, resulting in a greater understanding of the underlying pathophysiology, development of new diagnostic imaging tools, and a broadening array of targeted treatment options. This article reviews the clinical presentation and pathogenesis of SIH, discusses the important role of imaging in diagnosis, and describes how imaging guides treatment.

CSF volume provocation maneuvers during lumbar puncture as a possible predictive tool for diagnosing spontaneous intracranial hypotension.

OBJECTIVES: Spontaneous intracranial hypotension (SIH) is a pathologic state of low CSF volume caused by a CSF to venous fistula or CSF leak. It is diagnosed based on symptoms, imaging, and CSF pressure but is often a diagnostic challenge because no single test is highly sensitive. Physician-induced changes in CSF volume may result in changes in patient symptoms, as has been shown with idiopathic intracranial hypertension (IIH). The purpose of this study is to determine the sensitivity of CSF volume provocation maneuvers in the diagnosis of SIH. PATIENTS AND METHODS: We reviewed consecutive patients that underwent lumbar puncture from January 2015 to January 2017. Patients were included if they met ICHD3 criteria for SIH and CSF volume provocation maneuvers were performed. Cases were considered concordant if there was improvement of symptoms with addition of CSF. RESULTS: 1084 patients underwent 2250 CT-guided lumbar punctures from January 2015 to January 2017. 92 patients with SIH were identified and 62 of these patients underwent CSF volume provocation maneuvers. 58% (36/62) had concordant lumbar puncture encounters with symptom improvement upon addition of artificial CSF. CONCLUSION: CSF volume provocation maneuvers demonstrate 58% sensitivity for identifying patients with SIH, better than those reported for CSF opening pressure and myelography. A positive symptomatic response to CSF volume provocation maneuvers was independent of the other objective tests used for SIH and may aid in the often-challenging diagnostic workup of these patients. Future prospective case-controlled studies are needed.

Yttrium-90 selective internal radiation therapy, examining dose rates and radiation protection precautions.

METHODS: Dose rates from 30 patients, treated over a 3-year period (2016-2018) were measured post therapy in contact with the patients' upper abdomen and at distances of 0.3 m and 1 m. Dose rates were compared with theoretical predictions and used as model inputs for calculating radiation doses received by family members and carers based on interaction patterns previously described in the literature. RESULTS: The average dose rate per activity from SIRT patients were:- In contact: 29 ±â€¯23 µSv.h-1.GBq-1; 0.3 m: 4.1 ±â€¯2.34 µSv.h-1.GBq-1 and 1 m: 0.59 ±â€¯0.42 µSv.h-1.GBq-1. Dose rates measured at 0.3 and 1 m followed a predictable distribution. Estimated doses based on proximity models demonstrated restrictions to be advisable, depending on the administered activity, considering the dose constraint and limit of 0.3 and 1 mSv, respectively, employed within the EU. CONCLUSIONS: In accordance with local dose constraints, and depending on administered activities, radiation protection precautions may be necessary for those individuals in regular contact with patients who have receive 90Y SIRT. A radiation protection precautions calculator has been devised to offer personalised instructions taking into account the administered activity and proximity models.

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.

CT Fluoroscopy-Guided Interlaminar Epidural Steroid Injections in the Cervical Spine: Rate of Nontarget Injection Into the Retrodural Space of Okada.

OBJECTIVE: The purpose of this study was to assess the rate of inadvertent injection into the retrodural space of Okada during CT fluoroscopy-guided interlaminar epidural steroid injection in the cervical spine. MATERIALS AND METHODS: Images from cases of cervical interlaminar epidural steroid injection under CT fluoroscopic guidance performed at a single institution between November 2009 and November 2015 were obtained and reviewed. For all cases, the following information was recorded: presence or absence of contrast material within the Okada space, cervical anatomic level at which the procedure was performed, laterality of approach, trainee presence, and years of proceduralist experience. Two-tailed chi-square tests were used to assess categoric variables, and t tests were performed to assess for continuous variables predictive of nontarget injection. RESULTS: A total of 974 CT fluoroscopy-guided cervical interlaminar epidural steroid injections were identified in 728 patients. The presence of contrast material in the retrodural space of Okada was identified in 2.9% of cases (28/974). All cases of inadvertent injection were identified and corrected intraprocedurally. The greatest rate of inadvertent injection (4.6% [18/389]) occurred at C5-6. No variables predictive of inadvertent injection into the Okada space were identified. There was a 0.4% (4/974) complication rate, and all complications were minor. CONCLUSION: We identified a 2.9% rate of unintended injection into the retrodural space of Okada during cervical interlaminar epidural steroid injection. If unrecognized, these nontarget injections can result in treatment failure in a subset of patients who undergo cervical interlaminar epidural steroid injection. Future study is warranted to assess the rate of inadvertent Okada injection under conventional fluoroscopy and to compare the rates of detection between the two imaging-guided modalities.

CSF Venous Fistulas in Spontaneous Intracranial Hypotension: Imaging Characteristics on Dynamic and CT Myelography.

OBJECTIVE: The objective of this study is to describe the anatomic and imaging features of CSF venous fistulas, which are a recently reported cause of spontaneous intracranial hypotension (SIH). MATERIALS AND METHODS: We retrospectively reviewed the records of patients with SIH caused by CSF venous fistulas who received treatment at our institution. The anatomic details of each fistula were recorded. Attenuation of the veins involved by the fistula was compared with that of adjacent control veins on CT myelography (CTM). Visibility of the CSF venous fistula on CTM and a modified conventional myelography technique we refer to as dynamic myelography was also compared. RESULTS: Twenty-two cases of CSF venous fistula were identified. The fistulas were located between T4 and L1. Ninety percent occurred without a concurrent epidural CSF leak. In most cases (82%), the CSF venous fistula originated from a nerve root sleeve diverticulum. On CTM, the abnormal veins associated with the CSF venous fistula were seen in a paravertebral location in 45% of cases, centrally within the epidural venous plexus in 32%, and lateral to the spine in 23%. Differences in attenuation between the fistula veins and the control veins was highly statistically significant (p < 0.0001), with a threshold of 70 HU perfectly discriminating fistulas from normal veins in our series. When both CTM and dynamic myelography were performed, the fistula was identified on both modalities in 88% of cases. CONCLUSION: CSF venous fistulas are an important cause of SIH that can be detected on both CTM and dynamic myelograph y and may occur without an epidural CSF leak. Familiarity with the imaging characteristics of these lesions is critical to providing appropriate treatment to patients with SIH.

Update on the Diagnosis and Treatment of Spontaneous Intracranial Hypotension.

PURPOSE OF REVIEW: The purpose of this study is to provide an update on recent developments in the understanding, diagnosis, and treatment of spontaneous intracranial hypotension (SIH). RECENT FINDINGS: SIH is an important cause of headaches caused by spinal cerebrospinal fluid (CSF) leaks, with an increasingly broad spectrum of clinical presentations and diagnostic findings. A simple conception of the condition as being defined by the presence of low CSF pressure is no longer sufficient or accurate. A number of etiologies for spinal CSF leaks have been identified, including the recent discovery of CSF-venous fistulas, and these various etiologies may require different diagnostic and therapeutic pathways in order to affect a cure. Familiarity with the spectrum of presentations and causes of SIH is critical to accurate and timely diagnosis and management. Challenges exist in both diagnosis and treatment, and require understanding of the underlying pathogenesis of the condition in order to appropriately select testing and treatment. Prospective studies are needed going forward in order to inform workup and guide treatment decisions.

Time-Dependent Changes in Dural Enhancement Associated With Spontaneous Intracranial Hypotension.

OBJECTIVE: The objective of our study was to determine whether the presence of individual imaging signs of spontaneous intracranial hypotension (SIH) is correlated with increasing duration of headache symptoms. Of particular interest is the relationship of symptom duration to dural enhancement because it is the most commonly identified imaging sign in patients with SIH. MATERIALS AND METHODS: Eighty-nine patients with SIH who underwent pretreatment brain MRI and total-spine CT myelography and whose medical record included data on the duration of clinical symptoms were included in this cross-sectional retrospective study. Brain imaging was reviewed for the presence of dural enhancement, brain sagging, and the "venous distention" sign. CT myelograms were assessed for CSF leak. If present, a leak was subcategorized as a high-flow or low-flow leak. Differences in headache duration between subjects with and those without individual imaging signs were compared. RESULTS: Subjects without dural enhancement on brain MRI had a longer average duration of symptoms than those with dural enhancement present (average symptom duration: 45.3 ± 59.0 [SD] vs 15.1 ± 33.0 weeks, respectively; p = 0.002). No difference in symptom duration was observed between subjects whose MRI studies showed and those whose MRI studies did not show brain sagging (p = 0.10) or the venous distention sign (p = 0.21). The presence of a CSF leak on CT myelography was not associated with symptom duration (p = 0.56) except in the subgroup of patients with low-flow leaks. CONCLUSION: Increasing symptom duration in SIH is associated with decreased prevalence of abnormal dural enhancement on brain MRI. Because dural enhancement is considered a hallmark imaging feature of this condition, its absence may exacerbate the problem of underdiagnosis in chronic cases of SIH.