Presumptive Idiopathic Intracranial Hypertension Based on Neuroimaging Findings: A Referral Pattern Study

Radiologic findings of intracranial hypertension (RAD-IH) are common in idiopathic intracranial hypertension (IIH) patients. Paralleling the increasing rates of obesity, the burden of IIH is growing. Urgent neuro-ophthalmology consultations for possible IIH in patients with incidentally detected RAD-IH are increasing, with many patients receiving unnecessary lumbar punctures (LPs) and treatments. This retrospective observational study aimed to determine the prevalence of neuro-ophthalmology consultations for RAD-IH, rate of funduscopic examination by referring providers, prevalence of papilledema, outcomes after neuro-ophthalmic evaluation, and rates of misdiagnosis.

Original Contribution Section Editors: Clare Fraser, MD Susan Mollan, MD Presumptive Idiopathic Intracranial Hypertension Based on Neuroimaging Findings: A Referral Pattern Study Andre B. Aung, MD, Benson S. Chen, MBChB, FRACP, Jaime Wicks, MD, Beau B. Bruce, MD, PhD, Benjamin I. Meyer, MD, Michael Dattilo, MD, PhD, Sachin Kedar, MD, Amit Saindane, MD, Nancy J. Newman, MD, Valérie Biousse, MD Background: Radiologic findings of intracranial hypertension (RAD-IH) are common in idiopathic intracranial hypertension (IIH) patients. Paralleling the increasing rates of obesity, the burden of IIH is growing. Urgent neuro-ophthalmology consultations for possible IIH in patients with incidentally detected RAD-IH are increasing, with many patients receiving unnecessary lumbar punctures (LPs) and treatments. This retrospective observational study aimed to determine the prevalence of neuro-ophthalmology consultations for RAD-IH, rate of funduscopic examination by referring providers, prevalence of papilledema, outcomes after neuro-ophthalmic evaluation, and rates of misdiagnosis. Methods: Records of 1,262 consecutive new patients seen in one neuro-ophthalmology clinic from January 2019 to January 2020 were reviewed. We identified patients who were: 1) referred with concern for IIH because of findings of RAD-IH; 2) referred for “papilledema”; 3) referred with a diagnosis of IIH; and 4) referred for spontaneous cranial cerebrospinal fluid (CSF) leaks. In addition to basic demographic profiles for all groups, detailed information was collected for patients referred Department of Ophthalmology (ABA), Emory University School of Medicine, Atlanta, Georgia; Department of Ophthalmology (BSC), Emory University School of Medicine, Atlanta, Georgia; Department of Radiology and Imaging Sciences (JW), Emory University School of Medicine, Atlanta, Georgia; Departments of Ophthalmology, Neurology, and Epidemiology (BBB), Emory University, Atlanta, Georgia; Department of Ophthalmology (BIM), Emory University School of Medicine, Atlanta, Georgia; Department of Ophthalmology (MD), Emory University School of Medicine, Atlanta, Georgia; Departments of Ophthalmology and Neurology (SK), Emory University School of Medicine, Atlanta, Georgia; Departments of Radiology and Imaging Sciences and Neurological Surgery (AS), Emory University School of Medicine, Atlanta, Georgia; Departments of Ophthalmology, Neurology, and Neurological Surgery (NJN), Emory University School of Medicine, Atlanta, Georgia; andDepartments of Ophthalmology and Neurology (VB), Emory University School of Medicine, Atlanta, Georgia. The authors report no conflicts of interest. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www. jneuro-ophthalmology.com). Address correspondence to Valérie Biousse, MD, Departments of Ophthalmology and Neurology, Emory University School of Medicine, 1365 E Clifton Rd, Atlanta, GA; E-mail: [e-mail] Aung et al: J Neuro-Ophthalmol 2023; 43: 55-62 solely for RAD-IH, including referral patterns, prior history of IIH, previous LPs, prior medical or surgical treatment(s), risk factors for increased intracranial pressure (ICP), presenting symptoms, radiologic features observed on neuroimaging, and final disposition. When available, the neuroimaging was reviewed by an expert neuroradiologist. Results: Of 1,262 consecutive new patients, 66 (5%) were referred specifically for RAD-IH; most referrals came from neurologists (58%); 8/66 (12%) patients had papilledema; 16/66 (24%) patients had prior LP and 13/66 (20%) were already treated based on MRI findings; and 22/66 (33%) patients had #2 RAD-IH. Only 34/66 (52%) of patients referred for RAD-IH had prior funduscopic examinations. We confirmed papilledema in 26/82 (32%) patients referred for “papilledema.” Only 29/83 (35%) patients referred with a diagnosis of IIH had active papilledema, and 3/16 (19%) patients with spontaneous CSF leaks had papilledema. In total, 247/1,262 (20%) new patients were referred to our clinic over 1 year with concern for IIH, among whom only 66 (27%) were confirmed to have active IIH with papilledema. Conclusions: One in 5 new patient referrals seen in our neuro-ophthalmology clinic were referred because of concern for increased ICP, but only 1/4 had active papilledema. Most patients referred for isolated RAD-IH do not have papilledema, many having undergone unnecessary LPs and treatments. The burden of these “rule-out IIH” consultations is overwhelming and will only continue to increase with the concurrent rise of obesity and IIH, straining the already limited neuro-ophthalmologic resources available in the US. Journal of Neuro-Ophthalmology 2023;43:55–62 doi: 10.1097/WNO.0000000000001660 © 2022 by North American Neuro-Ophthalmology Society P apilledema is a key diagnostic criterion in idiopathic intracranial hypertension (IIH), the diagnosis of which also incorporates brain imaging criteria to rule out secondary causes of intracranial hypertension, elevated cerebrospinal fluid (CSF) opening pressure, and normal CSF constituents (1). An increasing number of secondary radiologic findings of intracranial hypertension (RAD-IH) have been recognized in IIH patients over the past 20 years. However, these RAD-IH signs 55 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution are not specific for IIH (2,3), and are often detected incidentally in patients undergoing brain imaging for any clinical indication (4). The findings of RAD-IH may indicate current or previously elevated intracranial pressure (ICP) or may not have an explanation, especially when observed in isolation (4–8). Examination of the ocular fundus remains the most important assessment to determine whether further work-up for a disorder of ICP is required, depending on the clinical context. However, previous studies have shown that many patients with RAD-IH undergo unnecessary procedures such as lumbar puncture (LP) or receive empirical treatment with acetazolamide, without documentation of papilledema (9,10). The increasing incidence of obesity and IIH has resulted in a growing rate of hospital admissions and demand for neuroophthalmic care (11-14). With increasing recognition of the association between RAD-IH and IIH, patients with incidentally detected RAD-IH are now routinely referred to neuroophthalmology to “rule out IIH,” often by well-meaning radiologists who suggest the diagnosis of IIH on radiology reports when incidental RAD-IH are identified on brain imaging (15). The purpose of this study was to analyze referral patterns to one neuro-ophthalmology clinic for suspected disorders of ICP, focusing on patients with RAD-IH. We aimed to determine the rate of funduscopic examination by referring providers; ascertain which procedures and treatments patients received before neuro-ophthalmic evaluation; establish the prevalence of papilledema and imaging findings of RAD-IH; characterize rates of misdiagnosis; and determine outcomes after neuro-ophthalmic evaluation. METHODS The study was approved by our institutional review board. We retrospectively reviewed all new outpatient encounters in one neuro-ophthalmology clinic in a tertiary care university hospital over 1 year (January 1, 2019–January 1, 2020; before the SARS-CoV-2 pandemic) to identify all patients seen for presumed disorders of ICP. We classified these patients into 4 groups based on the entire neuroophthalmological evaluation: Group 1) patients referred to us after discovery of RAD-IH on brain imaging obtained for any reason; Group 2) patients referred specifically because of confirmed or presumed papilledema or to rule-out papilledema; Group 3) patients referred for confirmed or presumed IIH, with or without papilledema; and Group 4) patients with confirmed spontaneous CSF leaks, referred because of concern for IIH as the cause of the CSF leak (Fig. 1). We collected demographic information for all included patients, including age, gender, race, and body mass index. Details of the neuro-ophthalmologic examination, including ocular imaging obtained at the time of the visit, were reviewed to identify patients with papilledema at the time of the neuro-ophthalmology evaluation. For the patients referred solely for RAD-IH (Group 1), further data were collected, including remote diagnosis of IIH, 56 prior LP, prior medical or surgical treatment for presumed or confirmed IIH; symptoms or signs of raised ICP (headaches, pulsatile tinnitus, transient visual obscurations, binocular diplopia, papilledema); and risk factors for IIH (weight gain, obesity, and exposure to medications). We also collected referral pattern information such as the specialty of the referring provider and the number of providers seen before neuroophthalmology consultation; the urgency of the referral (estimated by the number of days between neuroimaging performed and neuro-ophthalmology consultation); the specialty of the provider ordering the neuroimaging; and the type of neuroimaging ordered (CT, CTV, MRI, MRV). The final diagnosis after neuro-ophthalmology visit was recorded as 1) incidental RAD-IH, 2) presumed prior IIH, 3) confirmed prior IIH, or 4) current IIH with papilledema. We also documented the final disposition after neuro-ophthalmology visit (e.g., whether an LP was recommended, whether acetazolamide or topiramate were started, and the follow-up plan). All radiology reports were reviewed for any mention of RAD-IH (see list in Table 2) (2,4). All available imaging studies were also interpreted by a neuroradiologist and neuro-ophthalmologists looking specifically for RAD-IH, as previously described (2). Statistical analyses were performed with R: A language and environment for statistical computing (version 4.0.2, R Foundation for Statistical Computing, http://www.Rproject.org). Medians and interquartile ranges (IQR) were used to report continuous variables. Continuous variables were compared between groups using the Wilcoxon– Kruskal–Wallis test, with post-hoc testing with the Mann–Whitney U test. Chi-square or Fisher exact test, as appropriate, were used to compare the frequency distribution of categorical variables between groups. RESULTS Among the 1,262 new outpatients seen in one of our tertiary neuro-ophthalmology clinics over 1 year, we identified 247 patients (20%) referred to us with concern for a disorder of ICP. (Tables 1 and 2; Fig. 1). This included 66 patients (5% of all new patients seen) referred solely because of RAD-IH findings on brain imaging performed for any reason (Group 1), among whom 8 (12%) had papilledema confirmed in our neuro-ophthalmology clinic (Fig. 1). Thirty-four of these 66 patients (52%) had prior funduscopic examinations by an ophthalmologist (24), optometrist (5), or neurologist (5). Nine patients (14%) had prior documentation of presumed papilledema by outside providers (one by neurology, one by optometry, 7 by ophthalmology), which was confirmed in only 2 patients at the time of neuro-ophthalmology consultation. Funduscopic examination was not performed in 15/38 (39%) of patients referred by neurologists, 5/8 (63%) referred by otolaryngologists, 10/12 (83%) referred by neurosurgeons, 1/4 (25%) referred by ophthalmology, and one patient referred by endocrinology. We identified papilledema in 3/32 patients Aung et al: J Neuro-Ophthalmol 2023; 43: 55-62 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution FIG. 1. Categorization of 4 groups included in the study. RAD-IH: radiologic findings of intracranial hypertension (includes partially empty or empty sella, enlargement of Meckel cave, optic nerve head protrusion, posterior scleral flattening, optic nerve sheath dilation, tortuous optic nerves, meningocele/encephalocele, cerebellar tonsillar descent, transverse venous sinus stenosis, and skull base cerebrospinal fluid leak). (9%) who had not had a funduscopic examination before the neuro-ophthalmology consultation and in 3 patients who had documentation of a normal funduscopic examination by an outside ophthalmologist, all within the 5 months preceding neuro-ophthalmology evaluation (Figs. 2 and 3). Most neuroimaging studies (16 head CTs, 1 CTV, 60 brain MRIs, and 14 MRVs) were ordered by neurologists (61%). We were able to review the images from 58/66 radiologic studies and all 66 radiologic reports (Table 2). Excluding empty sella, our expert neuroradiologist significantly identified more RAD-IH signs than outside radiologists (See Supplemental Digital Content, Tables 1S and 2S, http://links.lww.com/WNO/A615), underscoring the general under-reporting of RAD-IH by nonspecialists. An LP had been previously performed by the referring provider in 16 of the 66 patients (24%) referred for RAD-IH (Table 2). After neuro-ophthalmology consultation, we recommended an LP in 2 patients (CSF-opening pressures: 27 and 31 cm water). LPs performed after the neuro-ophthalmology consultation at the request of the outside provider in 5 patients had a median opening pressure of 24 cm water (IQR: 22–28; range: 18–40 cm water). We recommended discontinuation of acetazolamide in 5 patients (8%). We initiated medical therapy with acetazolamide in 6 patients (9%) and arranged a neuroophthalmology follow-up to recheck the optic nerve appearance in 13 patients (20%). The final diagnosis in patients referred because of concern for intracranial hypertension after brain imaging was classified as: incidental RAD-IH (54 [82%]); presumed prior IIH (3 [5%]); confirmed prior IIH (1 [1%]); and current IIH (8 [12%]). Aung et al: J Neuro-Ophthalmol 2023; 43: 55-62 DISCUSSION In this retrospective observational study of new patients seen in one tertiary neuro-ophthalmology outpatient clinic over a oneyear period (pre-SARS-CoV-2 pandemic), almost one in 5 new patients were referred because of a suspected disorder of ICP. Five percent of all new referrals were generated by the discovery of RAD-IH, usually obtained for headache. The vast majority of these patients had incidental RAD-IH without papilledema and did not meet diagnostic criteria for IIH. Crucially, a diagnosis of current IIH with papilledema was made in only 8 (12.1%) of the 66 patients referred for RADIH, emphasizing the poor predictive value of isolated RAD-IH in identifying active IIH in patients undergoing routine brain imaging. The findings of our study challenge the widespread practice of performing a complete IIH work-up in patients with incidental RAD-IH and highlights the potential for patient harm with this approach (16,17). Despite multiple previous case–control studies (18–26), the diagnostic utility of RAD-IH in IIH is not fully elucidated. Some authors have determined the sensitivity and specificity of individual RAD-IH for detecting IIH by pooling these studies (2,3). The pooled sensitivity values for individual RAD-IH ranged between 6.1% and 97%; whereas pooled specificity values ranged between 84% and 99% (2,3). Limitations of this approach include variability in the definition of some RAD-IH, which IIH diagnostic criteria are used, which patients constitute the control group, and whether a measure of CSF opening pressure was obtained near the time of brain imaging. A recent retrospective cohort study of 204 consecutive participants seen 57 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution TABLE 1. Basic demographic information and presence of papilledema in the 4 groups of patients referred because of concern for a disorder of intracranial pressure Group 1 Group 2 Group 3 Demographics Patients Referred for RAD-IH (n = 66) Patients Referred for Papilledema (n = 82) Patients Referred for IIH (n = 83) Age (median, IQR) Female sex BMI (median, IQR) Papilledema No papilledema 43 55 33 8 58 29 74 34 26 56 (37–54) (83%) (28–42) (12%) (88%) (22–39) (90%) (28–41) (32%) (68%) 38 79 35 29 54 (30–46) (95%) (30–41) (35%) (65%) Group 4 Total Number of Patients Referred Patients Because of Concern Referred for CSF for a Disorder of Leaks Intracranial Pressure (n = 16) (n = 247) 49 15 34 3 13 (45–58) (94%) (31–43) (19%) (81%) 38 223 34 66 181 (28–47) (90%) (29–42) (27%) (73%) P ,0.001 0.109 0.709 0.0059 — BMI, body mass index; CSF, cerebrospinal fluid; IIH, idiopathic intracranial hypertension; IQR, interquartile range; RAD-IH, radiologic findings of intracranial hypertension. in 2 neuro-ophthalmology centers for bilateral optic nerve head appearance concerning for papilledema determined that the presence of any RAD-IH on MRI/MRV had a sensitivity of 74.8% and specificity of 94.7% for detecting IIH (27). TSS on MRI/MRV had the highest positive likelihood ratio (20.24; 95% CI: 2.89–141.17) for detecting IIH in their cohort, of whom 76.5% of participants fulfilled the 2013 diagnostic criteria for IIH (27). Although a useful sign, TSS is infrequently reported as an incidental RAD-IH, because it is most easily observed on a contrast-enhanced MRI or MRV or CTV, studies not routinely performed unless patients are evaluated for possible disorders of ICP (4,28). The predictive value of RAD-IH for diagnosing IIH depends on the prevalence of IIH in the population studied. RAD-IH are common in patients undergoing brain imaging for any clinical indication and may represent a current or previous state of intracranial hypertension from any cause. A recent prospective study found that in a cohort of 296 prospectively evaluated consecutive outpatients undergoing MRI brain for any clinical indication and who had ocular fundus photographs performed the same day, the prevalence of at least one RAD-IH was almost 50%, but only 5 participants had papilledema (of which only 2 had IIH) (4). Empty sella, optic nerve tortuosity, and TSS were significantly more frequent in patients with papilledema of any cause compared with those without papilledema. However, as shown in a previous prospective study, RAD-IH are often present in patients with no active papilledema (4). When RAD-IH are detected incidentally, a broad recommendation by the interpreting radiologist to “correlate the findings clinically” because of a possible association with IIH has the potential to generate unnecessary clinic visits and procedures and lead to patient harm (15). In this study, 14 patients underwent an unnecessary LP and 10 patients received empirical treatment with acetazolamide (8) or topiramate (2). Most patients with RAD-IH required no further management after ocular funduscopic examination ruled-out active papilledema. Such patients would likely benefit from medical treatment of 58 chronic headaches, and not from treatment specifically aimed at decreasing ICP. Indeed, as shown in the IIH Treatment Trial, acetazolamide therapy is not an effective treatment for headaches, even in confirmed IIH patients (29–31). In addition, RAD-IH without papilledema may reflect previously elevated ICP and not current intracranial hypertension, and therefore these patients do not always need an LP. It is likely that most RAD-IH (especially empty sella, TSS and bony changes) persist in treated IIH patients, even after papilledema has resolved and ICP has normalized (32,33). Despite the importance of funduscopy in the evaluation of patients with suspected disorders of ICP, nearly 50% of the patients referred to our clinic for RAD-IH did not have a funduscopic examination before being seen in our clinic. Non–eye-care providers, in particular neurosurgeons, were the least likely to perform a funduscopic examination. The rate of funduscopic examinations by eye-care providers, although better, was still incomplete. Over half of the referrals for RAD-IH on brain imaging were initiated by neurologists and could have potentially been avoided by completion of an ocular funduscopic examination without proceeding to LP. Although we did not assess the barriers that prohibited funduscopy in these patients, many non– eye-care providers are not comfortable with examining of the ocular fundus nor making a diagnosis of papilledema (34). Incorporation of nonmydriatic ocular fundus cameras in neurology clinics would facilitate routine examination of the ocular fundus in nonophthalmologic settings, potentially aided by automatic screening of photographs for the presence of papilledema using artificial intelligence (35–38). We acknowledge that there are rare disorders of intracranial hypertension that do not manifest with papilledema, particularly the so-called “IIH without papilledema” (IIHWOP) (39). This is a rare and poorly understood condition that should only be considered by a headache specialist in patients with refractory chronic headaches, and not a diagnosis to be made simply because a patient has headache and incidentally detected RAD-IH (40). As patients with IIHWOP do not have Aung et al: J Neuro-Ophthalmol 2023; 43: 55-62 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution TABLE 2. Characteristics of the 66 patients referred for isolated radiologic signs of intracranial hypertension (Group 1: RAD-IH) comparing patients found to have papilledema with those without papilledema All Patients (n = 66) Age (median, IQR) 43 (37–54) Female sex 55 (83%) BMI (median, IQR) 33 (28–42) Race/ethnicity African American 37 (56%) Caucasian 27 (41%) Hispanic 2 (3%) Urgency of referrals 35 (113–20, Median number of days between 2–762) neuroimaging and neuro-ophthalmology consultation (IQR, range) Average number of providers seen before 2.5 neuro-ophthalmology Number of providers seen before neuro-ophthalmology 1 11 (17%) 2 28 (42%) 3 15 (23%) 4 5 (7%) 5 6 (9%) 6 1 (2%) Referring provider Neurology 38 (58%) Neurosurgery 12 (18%) Otolaryngology 8 (12%) Ophthalmology 4 (6%) Primary care provider 3 (4%) Endocrinology 1 (2%) Lumbar puncture before referral to neuro-ophthalmology* Yes 16 (24%) No 50 (76%) Treatment with acetazolamide or topiramate prior to referral to neuro-ophthalmology Yes 13 (20%) No 53 (80%) Surgical treatment before referral to neuro-ophthalmology Yes 0 (0%) No 66 (100%) Possible risk factors for intracranial hypertension Previous (remote) diagnosis of IIH 6 (9%) Recent weight gain 21 (32%) Exposure to medications associated with 6 (9%) intracranial hypertension Presenting symptoms Headaches 58 (88%) Pulsatile tinnitus 17 (26%) Blurry vision 28 (42%) Transient visual obscurations 6 (9%) Binocular diplopia 3 (5%) Reason for neuroimaging request Headaches 30 (47%) IIH/papilledema 5 (8%) Aung et al: J Neuro-Ophthalmol 2023; 43: 55-62 Patients With Papilledema (n = 8) Patient Without Papilledema (n = 58) 37 (33–47) 6 (75%) 33 (29–38) 45 (38–54) 49 (85%) 34 (28–42) 5 (63%) 3 (37%) 0 (0%) 32 (55%) 24 (41%) 2 (4%) 30 (26–49, 9–70) 36 (21–131, 2–762) 0.5 3.0 2.8 0.5 P 0.1 0.6 0.96 1 0.5 (19%) (43%) (21%) (7%) (8%) (2%) — — — — — — 0.6 — — — — — — 1.0 0 (0%) 3 (38%) 3 (38%) 1 (12%) 1 (12%) 0 (0%) 11 25 12 4 5 1 5 (63%) 2 (25%) 0 (0%) 1 (12%) 0 (0%) 0 (0%) 33 (57%) 10 (17%) 8 (14%) 3 (5%) 3 (5%) 1 (2%) 2 (25%) 6 (75%) 14 (24%) 44 (76%) — — 0.185 3 (37%) 5 (63%) 10 (17%) 48 (83%) — — 1.0 0 (0%) 8 (100%) 0 (0%) 58 (100%) — — 1 (12%) 2 (25%) 0 (0%) 5 (9%) 19 (33%) 6 (10%) 0.56 1.0 1.0 7 (88%) 4 (50%) 5 (63%) 1 (13%) 0 (0%) 51 13 23 5 3 (88%) (22%) (40%) (9%) (5%) 1.0 0.19 0.27 0.56 1.0 3 (44%) 1 (14%) 27 (47%) 4 (7%) 1.0 0.45 59 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution (Continued ) All Patients (n = 66) Epilepsy/seizures Hearing abnormalities/tinnitus Chiari malformation Syncope/vertigo Other N/A Radiologic findings suggestive of intracranial hypertension (RAD-IH) Partially empty/empty sella Enlarged Meckel cave Optic nerve head protrusion Posterior scleral flattening Optic nerve sheath dilation Tortuous optic nerves Meningocele/encephalocele Cerebellar tonsillar descent Transverse venous sinus stenosis Skullbase CSF leak Number of RAD-IH 1 2 3 4 5 or more Patients With Papilledema (n = 8) Patient Without Papilledema (n = 58) P 5 5 4 4 11 (8%) (8%) (6%) (6%) (17%) 2 1 (14%) 0 (0%) 1 (14%) 0 (0.0%) 1 (14%) 1 4 5 3 4 10 (7%) (9%) (5%) (7%) (18%) 1 0.45 1.0 0.38 1.0 1.0 55 22 4 30 40 14 13 13 29 0 (83%) (33%) (6%) (45%) (61%) (21%) (20%) (20%) (44%) (0%) 7 (88%) 3 (38%) 0 (0%) 6 (75%) 7 (88%) 1 (13%) 2 (25%) 4 (50%) 6 (75%) 0 (0%) 48 (83%) 19 (33%) 4 (7%) 24 (41%) 33 (57%) 13 (22%) 11 (19%) 9 (16%) 23 (40%) 0 (0%) 9 (14%) 13 (20%) 14 (21%) 13 (20%) 17 (26%) 1 (12%) 0 (0%) 1 (12%) 2 (25%) 4 (50%) 8 (14%) 13 (22%) 13 (22%) 11 (20%) 13 (22%) 1.0 1.0 1.0 0.13 0.13 1.0 0.65 0.04 0.13 1.0 0.06 — — — — — *The CSF-opening pressure was not documented in 3 patients and the median pressure was 27 cm water (IQR: 21–28; range: 16–35 cm water) in the remaining 13 patients. Seven patients (44%) did not have improvement in their symptoms after LP, and 4 (25%) developed low CSF pressure headaches, with 3 of these patients seeking relief at an emergency department, 2 of whom received a blood patch. BMI, body mass index; CSF, cerebrospinal fluid; ICP, intracranial pressure; IIH, idiopathic intracranial hypertension; IQR, interquartile range; N/A, not available; RAD-IH, radiologic findings of intracranial hypertension. papilledema, there is no threat of vision loss among these patients (39) and the management of patients with IIHWOP is primarily focused on treatment of headache. Although headache in IIHWOP may at least partially improve with normalization of ICP, this benefit is often short-lived and should not be considered a diagnostic feature of IIHWOP (41,42). Proposed diagnostic criteria for IIHWOP mandate specific imaging criteria, clinical features, normal CSF examination, and a CSF opening pressure cut-off (1). However, variations in CSF pressure measured by LP and the lack of a definitive cut-off FIG. 2. Presence of papilledema in Group 1 patients in comparison to prior funduscopic examination findings. RAD-IH: radiologic findings of intracranial hypertension (includes partially empty or empty sella, enlargement of Meckel cave, optic nerve head protrusion, posterior scleral flattening, optic nerve sheath dilation, tortuous optic nerves, meningocele/encephalocele, cerebellar tonsillar descent, transverse venous sinus stenosis, and skull base cerebrospinal fluid leak). 60 Aung et al: J Neuro-Ophthalmol 2023; 43: 55-62 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution FIG. 3. Presence of papilledema in Group 1 patients in comparison to the different number of radiologic signs of increased intracranial pressure present. RAD-IH: radiologic findings of intracranial hypertension (includes partially empty or empty sella, enlargement of Meckel cave, optic nerve head protrusion, posterior scleral flattening, optic nerve sheath dilation, tortuous optic nerves, meningocele/encephalocele, cerebellar tonsillar descent, transverse venous sinus stenosis, and skull base cerebrospinal fluid leak). value for “normal” CSF opening pressure make this diagnosis very challenging (18,39). Our study has limitations mostly related to the retrospective nature of the study. Because we only included patients seen in our outpatient clinic, the magnitude of referrals for RAD-IH is underestimated by this study. We did not include inpatient and emergency department neuro-ophthalmology consultations, where many patients are sent by outside providers after RAD-IH are discovered. These inpatient consultations are anecdotally very common but could not be tracked over the study period. It is also possible that the LP or the initiation of medical treatment before the neuroophthalmology visit led to resolution of mild papilledema in some patients, possibly underestimating the proportion of RAD-IH patients with papilledema. However, most patients with prior treatment were seen relatively early by us and it is unlikely that papilledema would have completely resolved in most cases. We only reviewed the reports (not the scan themselves) for 8 of the 66 patients with RAD-IH. Interestingly, our expert neuroradiologist identified significantly more RAD-IH signs on the reviewed scans than were reported by outside radiologists, further highlighting that RAD-IH are very common and likely underreported. In conclusion, referrals to “rule out papilledema” or “rule out IIH” constitute a considerable proportion of the current neuro-ophthalmology workload. These referrals are likely to increase with the rising incidence of obesity and IIH, and the ever-growing ease and accessibility of brain imaging in headache patients. Papilledema can be ruled-out by any eye-care provider with the help of standard ocular imaging, including ocular fundus photography and optical coherence tomography (43). Most patients referred for incidentally discovered RAD-IH do not have papilledema and are not ultimately diagnosed with IIH. These patients most often do not require any further investigations once the absence of papilledema is confirmed. Proceeding to systematic LP or empiric treatment with acetazolamide in patients without papilledema has the potential to cause patient harm. Instead, inciden- Aung et al: J Neuro-Ophthalmol 2023; 43: 55-62 tal RAD-IH patients without papilledema should be reassured and those with headaches would benefit from medical treatment in headache centers rather than urgent referral to emergency departments or neuroophthalmology clinics. Given the shortage of neuroophthalmologists and the importance of ruling out disc edema before further intervention, clinicians who are uncomfortable or are not able to evaluate the optic nerve appropriately should consider referral to their optometry or general ophthalmology colleagues to “rule-out papilledema,” as referral to neuro-ophthalmology may be delayed and likely could be used more appropriately. STATEMENT OF AUTHORSHIP Conception and design: A. B. Aung, B. S. Chen, B. I. Meyer, A. Saindane, N. J. Newman, V. Biousse; Acquisition of data: A. B. Aung, B. S. Chen, J. Wicks, B. I. Meyer, M. Dattilo, S. Kedar, A. Saindane, N. J. Newman, V. Biousse; Analysis and interpretation of data: A. B. 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