Should Lumbar Puncture Be Required to Diagnose Every Patient With Idiopathic Intracranial Hypertension?

Point Counter-Point Section Editors: Andrew G. Lee, MD Gregory Van Stavern, MD Should Lumbar Puncture Be Required to Diagnose Every Patient With Idiopathic Intracranial Hypertension? Heather E. Moss, MD, PhD, Edward A. Margolin, MD, Andrew G. Lee, MD, Gregory P. Van Stavern, MD Drs. A. G. Lee and G. P. Van Stavern Idiopathic intracranial hypertension (IIH) is a disorder uniquely within the purview of neuro-ophthalmologists. Although overall a rare condition, patients with IIH are commonly diagnosed and managed primarily by neuroophthalmologists. Although the criteria for IIH has changed over the years, a constant feature of the modified Dandy criteria for IIH has been the requirement for lumbar puncture (LP) to confirm the diagnosis and to exclude alternative etiologies. Given the advancements in neuroimaging technology and better understanding of the range of intracranial pressure (ICP), 2 experts debate whether LP is still necessary for the diagnosis of IIH. Should Lumbar Puncture Be Required to Diagnose Idiopathic Intracranial Hypertension in Every Patient—Yes!—H. E. Moss, MD, PhD High ICP causes IIH’s major morbidities of vision loss and headache. Accordingly, ICP is the target of both medical and surgical therapies for IIH, and measurement of ICP is the cornerstone of diagnosis. Although what constitutes abnormally high ICP has evolved over the years, all past and current diagnostic criteria require LP for measurement of opening pressure (OP). Furthermore, LP enables cerebrospinal fluid (CSF) analysis to exclude secondary causes of high ICP. Some criteria allow for diagnosis of possible or probable IIH without LP, but none allow for definitive diagnosis of IIH without LP and CSF analysis. Thus, LP is necessary in every patient to diagnose definitive IIH by current guidelines. LP is an invasive procedure, one that is increasingly harder to arrange and not enjoyed by patients. Thus, it has been proposed that LP may not be necessary to diagnose IIH in every patient. As with any clinical decision risk, benefit analysis can be helpful (Table 1). By deferring LP, procedure complications and false results are avoided, which Departments of Ophthalmology and Neurology & Neurological Sciences (HEM), Stanford University, Stanford, California; Department of Ophthalmology and Visual Sciences (EM), University of Toronto, Toronto, Ontario; Blanton Eye Institute (AGL), Houston Methodist Hospital, Houston, Texas; and Department of Ophthalmology and Visual Sciences (GPVS), Washington University in St. Louis School of Medicine, St. Louis, Missouri. The authors report no conflicts of interest. Address correspondence to Gregory P. Van Stavern, MD, Department of Ophthalmology and Visual Sciences, Washington University in St. Louis School of Medicine, St. Louis, MO 63110; E-mail: [e-mail] Moss et al: J Neuro-Ophthalmol 2021; 41: 379-384 may increase both doctor and patient satisfaction. However, by deferring LP, the diagnosis is not confirmed and alternative diagnoses are not excluded. Specifically, measurement of OP, CSF analysis, and evaluating patient response to short-term ICP lowering are not accomplished. There are some patients who have high pretest probability for IIH based on weight, papilledema, and neuroimaging findings suggestive of high ICP, and some diagnostic criteria allow for diagnosis of probable IIH on this basis. In these patients, it has been proposed that LP is unlikely to change management and that they can be treated presumptively. My debate opponent has compiled a series of 68 patients with mild papilledema from presumed IIH who, despite lack of LP, were managed without negative outcomes (1). Similarly, a multicenter study reports 156 patients with probable IIH in whom LP did not change management (2). However, both of these studies suffer from selection bias in that the subjects were all seen by expert neuro-ophthalmologists. Scaling their success to other practitioners less expert in optic nerve assessment is fraught with the risk of missed diagnoses and overdiagnosis. Even in expert hands, the pretest probability that a patient has IIH never reaches 100%. A risk of not doing LP in these patients is failure to diagnose and treat a condition other than IIH that is causing their symptoms and signs. For example, compression of the optic nerve in the posterior orbit or canal can cause bilateral optic nerve edema similar to papilledema but without high ICP. An LP with normal OP would lead to consideration of this and further anatomical evaluation of the posterior orbit. In 379 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Point Counter-Point TABLE 1. Risks and benefits of doing or not doing an LP in suspected cases of IIH Risks Benefits Perform Procedure complications LP False-positive/negative results Defer LP Failure to diagnose normal ICP (necessitating evaluation for other causes of symptoms) Failure to diagnose secondary cause of high ICP Inappropriate medical or surgical treatment because of incorrect diagnosis addition, some secondary causes of high ICP require CSF analysis for diagnosis. Multiple studies in the literature illustrate the nonzero likelihood of conditions with substantial morbidity being overlooked in the setting of presumed IIH diagnosis. A single center study of 86 previously diagnosed cases of IIH included one with cerebral venous sinus thrombosis (3). In a multicenter study of 496 consecutive new neuro-ophthalmology referrals (102 referred for papilledema or abnormal optic disc appearance), one of these (0.2% of all patients and 1% of patients with papilledema) was a previously missed diagnosis of secondary elevated ICP (4). Another multicenter study of 206 patients referred to neuro-ophthalmology for the assessment of papilledema included 4 who were found to have non-IIH diagnoses requiring directed therapy including uveitis, meningitis, and leptomeningeal carcinomatosis (Helen Danesh-Meyer, MD, PhD, FRANZCO, personal written communication, May 2021). All these had positive neuroimaging findings suggesting high ICP and no neuroimaging findings suggesting a secondary cause. The previous paragraph discussed the problem of overdiagnosis of IIH leading to missed diagnosis of other conditions with high morbidity needing directed treatment. The corollary of this is overdiagnosis of IIH leading to Diagnostic confirmation Short-term treatment of ICP No procedure complications Money saved Resources saved unnecessary diagnostic testing and treatment. In the Fisayo study, 16 of 86 patients previously diagnosed with IIH had pseudopapilledema (3), which is a clinical diagnosis not necessitating any additional workup. In the Stunkel study, 15 of 89 patients with suspected papilledema due to IIH were rediagnosed to have pseudopapilledema (4). Although I do not advocate for LP to be performed for workup of pseudopapilledema, in cases where there is diagnostic uncertainty due to nonexpert or equivocal optic nerve examination, LP would prevent a false diagnosis of IIH and reduce harm due to unnecessary medical or even surgical treatment, which was proposed for 4 of 34 patients found to be misdiagnosed with IIH in the Fisayo study (3). In conclusion, LP is an important component of IIH diagnostic criteria because it confirms high ICP and excludes secondary causes of high ICP. Presumptive diagnosis of IIH on the basis of high body mass index (BMI), headache, bilateral optic disc abnormalities, and/or neuroimaging findings of high ICP leads to overdiagnosis of IIH due to failure to confirm the diagnosis and exclude other diagnoses. The consequences are inadequate treatment for a missed diagnosis or inappropriate testing and/or treatment for IIH. It is therefore important to follow the accepted diagnostic criteria including LP for diagnosing this condition. Is Lumbar Puncture Necessary for the Diagnosis of Idiopathic Intracranial Hypertension? Not Always—E. Margolin, MD LP is part of the modified Dandy criteria for establishing the diagnosis of IIH and is considered by many to be the cornerstone for making the diagnosis. The purpose of LP is 2-fold: To confirm increased OP of CSF during the procedure, which is an indirect indication of ICP, and to check its composition to rule out other more ominous causes of increased ICP, either an infection or, very rarely, a neoplasm. The main disadvantage of obtaining an LP is of course the pain and discomfort to the patient during the procedure as well as intraprocedural and postprocedural side effects of which the most common is severe headache due to persistent CSF leak from the site of dural puncture (5). LP can also be difficult to arrange for practitioners who are nonneurologists, and the technical difficulties in performing 380 an LP are often exacerbated by the fact that most patients with IIH have increased BMI. As more and more LPs are performed through fluoroscopic guidance, radiation exposure from fluoroscopy is also not trivial. As most neuro-ophthalmologists are aware though, the LP in a patient who is in a typical demographic group for IIH (women of childbearing age with increased BMI) will demonstrate expected results: elevated OP and normal CSF composition. We know that OP during LP does not correlate with the severity of the disease nor with visual prognosis (6,7). Neuroimaging, which would have been performed before an LP, should demonstrate indirect neuroimaging signs in nearly all patients suspected of having IIH. As experienced neuroMoss et al: J Neuro-Ophthalmol 2021; 41: 379-384 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Point Counter-Point ophthalmologists are also aware, the composition of CSF in patients who are in a typical demographic group for IIH, have typical symptoms, and are systemically well is nearly always normal. Thus, the question of this point counter-point article: “Does one really need to obtain an LP for patients who are in a typical demographic group for IIH, have typical symptoms, and are otherwise systemically well?” The incidence of side effects of LP is not trivial. Post-LP headache occurs in up to 25% of patients (5) and requires placement of a blood patch in a significant minority of patients. Rarer side effects include meningitis, nerve root pain, infection at the skin site, and very rarely an epidural abscess (8). One should also be aware that the OP number obtained during LP is not always an “absolute truth” and is prone to error. Multiple factors can influence OP on LP including positioning of the patient, inadvertent Valsalva maneuver during the procedure, needle positioning, and characteristics of the needle being some of the confounders (9,10). Thus, if the OP is under 25 cm of water in a patient who is in a typical demographic group for IIH and has bilateral optic nerve head edema with indirect neuroimaging signs of ICP, one would have to assume that either the OP is erroneous or that the normal value is not the same for all individuals and proceed with treating the patient for IIH. There are definitely many situations when obtaining OP and CSF analysis is very useful: It should be performed in all patients who are not in a typical demographic group for IIH, in those who have symptoms not typical for IIH, and where pseudopapilledema is difficult to rule out and the clinician is suspecting increased ICP as an additional cause for optic nerve head edema. LP is also needed for those patients who have a severe disease that is typically defined by abnormal visual function [decreased central acuity and/ or decreased mean deviation (MD) on automated perimetry, previously defined as MD worse than 27.0 dB] and for those patients in whom surgical treatments are planned (11). Although there are only a few studies (1,2) evaluating the management of patients with IIH without an LP, several IIH cohorts reported on the findings of the LP. One study evaluating 53 patients with IIH in Kuwait reported normal CSF composition in all (12). In the IIH Treatment Trial, although the explicit data regarding the number of patients who were found to have abnormal CSF composition at the study entry were not provided, Dr. Michael Wall, one of the study’s founders, kindly provided the spreadsheet with the details of each excluded patient for the purposes of this article. Abnormal CSF composition is not listed for any of them (13). My colleagues at the University of Toronto and myself followed a cohort of 68 patients with mild presumed IIH without an LP for at least 63 weeks, with no alternate diagnosis made in any of the patients and all the patients remaining well (this manuscript is currently under considMoss et al: J Neuro-Ophthalmol 2021; 41: 379-384 eration), again providing data about the reasonableness of following patients with mild presumed IIH without an LP. Modern neuroimaging has allowed us to be able to presume a diagnosis of IIH with a high degree of certainty as most patients will demonstrate several indirect neuroimaging features associated with increased ICP with transverse sinus stenosis been reported to be present in nearly all patients with IIH (14). Adequate neuroimaging (MRI with venography and contrast administration) can also effectively rule out many alternate diagnoses. Thus, if LP is not performed, a high-quality MR scan of the brain with venography sequences and contrast administration is paramount. When searching previous reported cases of misdiagnosis of IIH when LP was not performed, no definitive reports were found where the patient was in a typical demographic category for IIH who did not have “red-flag” symptoms at presentation. One study retrospectively reviewed all patients who were diagnosed with aseptic meningitis and who also had increased OP on LP (15). Seven patients met both criteria and had an increased number of white blood cells in CSF with lymphocytic predominance. However, all patients were younger than 19 years, 6 were male, and papilledema was documented in 3 patients only, 2 of whom had neck stiffness with only 1 patient without other constitutional symptoms at presentation, who was 10-year-old. This study highlights the rarity of aseptic meningitis presenting with isolated papilledema and no other red flags on history or examination. Another study reported 3 patients with cryptococcal meningitis all of whom had papilledema; however, 2 were immunocompromised and the third patient had neuroretinitis-like picture at presentation (16). One report highlighted a 21-year-old male patient who presented with papilledema that was eventually linked to aseptic meningitis because of acute HIV infection; the patient had decreased central visual acuity at presentation and a low-grade fever (17). Another report described a 9year-old boy who presented with symptoms of increased ICP and papilledema and was eventually diagnosed with neuroborreliosis (18). Another article described a 32-yearold woman who had papilledema and increased OP on LP and was found to have human herpesvirus-6 in the CSF. She had a BMI of 48 kg/m2; however, she had a new onset of thunderclap headaches associated with photophobia, nausea, and vomiting, which were not responsive to oral analgesics and sumatriptans (19). Several reports described spinal cord tumors misdiagnosed as IIH: In one, the patient was a 41-year-old woman, who was not obese (exact BMI was not reported), had bilaterally decreased vision and a “left nasal hemianopia” with mildly dilated ventricles on MRI; in the second report, the patient was a 48-year-old man with normal neuroimaging whose BMI was not reported; in the third report, a 41-year-old man complained of distortion of peripheral vision and was found to have papilledema, and his OP on LP was normal, but because of the increased protein in CSF, he was eventually diagnosed with 381 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Point Counter-Point spinal cord plasmacytoma; in the fourth report, a morbidly obese 41-year-old woman experienced progressive visual loss, headaches, nausea, and vomiting and was found to have papilledema and anisocoria and was eventually diagnosed with intramedullary astrocytoma as a culprit producing elevated CSF protein (19–23). Another report highlighted a young man who presented with papilledema and was eventually diagnosed with carcinomatous meningitis due to adenocarcinoma of the lung; the patient was a very thin 30-year-old man (24). Two cases of spinal leptomeningeal lymphoma were reported that mimicked IIH: A 43-year-old woman, whose BMI was not reported had symptoms of headaches and dizziness for a year, was found to have papilledema and elevated CSF protein and eventually abnormal spinal MRI led to the diagnosis; the second case was that of a 49-year-old man, whose BMI was also not reported and who also had symptoms of increased ICP, was found to have papilledema while MRI of the brain was normal, and eventually, LP was performed demonstrating increased protein, and MRI of the spine led to the final diagnosis (25). These reports emphasize that although very rarely patients with underlying central nervous system infection or malignancy can present with isolated symptoms of increased IIH and normal brain imaging, they practically never fit all the criteria outlined below that sum up the characteristics of a patient with presumed IIH where LP can be safely deferred. Of course, an important caveat for the conclusion that LP is not necessary for the diagnosis of IIH in patients who are in a typical demographic category is that the involvement of an experienced neuro-ophthalmologist is required —someone who can recognize atypical features of the disease at presentation or during follow-up. In conclusion, the purpose of performing LP before diagnosing a patient with IIH is 2-fold: To confirm elevated OP and to rule out mimickers of IIH by establishing its normal composition. In a large cohort of patients with typical IIH reported in this issue of JNO where LP was performed at diagnosis, it did not change the management in any patient and an alternate diagnosis was not established in any patient (2). Several large cohorts of patients with typical IIH reported in the literature echo this finding. Review of individual reports describing misdiagnosis of IIH in the absence of LP did not yield any results where the patient was both in the typical demographic group for IIH and did not have any red flags on their presentation. Thus, one can conclude that in a patient with presumed papilledema who is in a typical demographic group for IIH (women aged 18–45 years with increased BMI), has no red-flag symptoms at presentation and is systemically well, had adequate neuroimaging that confirmed expected indirect neuroimaging findings of increased ICP and no other pathology, and has mild to moderate IIH where surgical treatment is not planned, LP may not be required for the diagnosis if the follow-up by an experienced neuro-ophthalmologist is available. Rebuttal—Dr. H. E. Moss Dr. E.M. and I agree about many things. First, we agree on the facts that, namely current diagnostic criteria for IIH require LP, LP is helpful to measure ICP and evaluate for secondary causes of high ICP, patients do not like LPs, there is a risk of procedural complications, and false-positive and false-negative results can complicate management. Second, we share the opinion that there are situations in which LP for workup of suspected IIH is critically important. These include situations in which the pretest probability for a disease other than IIH is higher such as for patients with atypical demographics or with “red-flag” symptoms. These also include situations in which the risk of incorrect IIH diagnosis and resultant incorrect management is higher such as for patients with severe vision loss or in whom a surgical intervention is planned. Third, we agree on the importance of an experienced neuro-ophthalmologist being involved in the care of patients with suspected IIH so that features suggesting the diagnosis is not IIH can be identified and appropriate management instituted. Dr. E.M. makes the excellent point that there are many patients for whom the final outcome is not affected by a 382 lack of LP. Although I do not routinely recommend against LP in my own practice, I have managed plenty of patients with likely IIH without LP because of their active refusal to get the test or more passive test avoidance by not attending the appointment or even canceling it. I do not recall any bad outcomes as a result. However, I do not think we should go so far as to routinely recommend against LP, even for specific subpopulations. The pretest probability may approach but never reaches 100%. A low risk of a severe disease bears consideration and discussion with the patient. My other concern is that it is not practical to have a neuro-ophthalmologist involved in every case of suspected IIH because we are in short supply (26). Nonexperts will be involved, and it is incumbent on us to provide guidance on diagnosis and management. Any message that LP is optional is at risk of misinterpretation and misapplication. Hence, let us keep it simple and follow the diagnostic criteria, which require LP. If a patient declines to get the test, we can still manage them, after appropriate education about what information is missing and the diagnostic uncertainty that that creates. Moss et al: J Neuro-Ophthalmol 2021; 41: 379-384 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Point Counter-Point Rebuttal—Dr. E. Margolin I thank Dr. H.E.M. for writing an elegant piece about why LP is important as a part of diagnostic process in patients with IIH. Her main argument is that an LP allows confirmation of diagnosis by measuring OP of CSF and allows ruling out of alternate diagnosis by evaluating CSF content. Dr. H.E.M. argues that both articles published in this issue of JNO suffer from selection bias because evaluation and management of patients was performed by expert neuro-ophthalmologists (1,2). I agree with this, and thus, the recommendation for avoiding the LP in a select group of patients includes availability of expert neuroophthalmological opinion and follow-up. Example of optic nerve compression in the posterior orbit or optic canal has been provided as one scenario where optic nerve head may be elevated but CSF OP will be normal thus an alternate diagnosis will be considered based on the LP. I would counter that in this particular scenario one would expect central visual acuity to be decreased. In addition, optic nerve compression anywhere along its pathway should also be visible on MRI of the brain and orbit with contrast enhancement, a study that should be performed in all patients with suspected IIH where LP is not performed. Regarding a referenced study where there was one case of dural venous sinus thrombosis in a cohort of 86 patients with IIH (3), I would counter again that if the imaging study detailed above would have been performed, this misdiagnosis would have been avoided. Furthermore, LP in the case of dural sinus thrombosis is not helpful in making the diagnosis because it would have indicated increased OP with normal constituents, thus pointing one toward making the erroneous diagnosis of IIH if appropriate neuroimaging has not been performed. It is difficult to comment on a recent article by Stunkel et al (4), where 1 of 102 patients referred for papilledema or abnormal optic disc appearance had a previously missed diagnosis of secondary elevated ICP because no details of this case were provided in the study, and we do not know whether LP was critical in making or changing the diagnosis. It is also difficult to comment on the study where 4 of 206 patients who were referred for papilledema were found to have a non-IIH diagnosis (M. T. M. Wang, Z. J. Prime, W. Xu, personal communication, Diagnostic performance of neuroimaging in suspected idiopathic intracranial hypertension) (uveitis, meningitis, and leptomeningeal carcinomatosis) because this study has not been published yet; however, uveitis would have been obvious on ophthalmic examination, Moss et al: J Neuro-Ophthalmol 2021; 41: 379-384 and a patient with meningitis is unlikely to have been systemically well. One patient with leptomeningeal carcinomatosis had reportedly normal neuroimaging; we do not know whether the MRI was performed with contrast and whether there were other clues to an alternate diagnosis. It is also unclear whether this patient had a known history of cancer and whether all these non-IIH patients fit into a typical demographic group for IIH. I will now address the argument that not performing LP can lead to overdiagnosis of IIH in patients who have pseudopapilledema. In almost all cases of pseudopapilledema, an expert neuro-ophthalmic examination and appropriate diagnostic testing such as fundus autofluorescence, orbital ultrasound, and enhanced depth imaging optical coherence tomography would be sufficient to make a diagnosis; on top of that, it is unlikely that these patients would demonstrate indirect neuroimaging signs of increased ICP: Prevalence of transverse sinus stenosis is almost 100% in patients with IIH, and by contrast, only 2% of patients in one recent study evaluating incidental prevalence of radiological signs of increased ICP and no papilledema on clinical examination had evidence of transverse sinus stenosis (27,28). Thus, the presence of transverse sinus stenosis is a very sensitive indirect radiological sign indicating likely the presence of increased ICP and can serve as a substitute for OP on LP in these cases. Finally, patients with pseudopapilledema most of the time have normal or near-normal visual function and should not be treated aggressively even if suspected of having IIH. If they fit into a typical demographic group for IIH, have normal visual function, and are thus given a recommendation for weight loss, this would not have any harmful effect. In summary, if the recommendation of avoiding LP is applied to the selected group of patients detailed below, LP can be safely avoided without the risk of missing an alternate diagnosis that would make a difference in the treatment. This select group of patients should 1) be women of reproductive age with increased BMI, 2) have no red-flag symptoms and be systemically well, 3) have normal or near-normal visual function (normal central acuity and mean deviation less than 7 dB on automated visual fields), 4) have MRI and MRV of the brain and orbits with contrast that is unremarkable other than the presence of indirect imaging signs of increased ICP, and, finally, 5) be under the care of a neuro-ophthalmologist experienced in diagnosing and treating patients with IIH. 383 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Point Counter-Point Conclusion—Drs. G. P. Van Stavern and A. G. Lee The diagnostic criteria of IIH have been modified several times in the past, in response to changes in technology and our understanding of the disease (e.g., MR venography). However, LP has been considered mandatory in each revision of the modified Dandy criteria for IIH. It is conceivable that in very select patients, with classic clinical and neuroimaging features, LP could be deferred unless the clinical course deviated from what is expected for IIH. The downside is the risk of overdiagnosing and overtreating patients without IIH and missing and delaying diagnosis of patients with alternate, potentially more serious conditions. Further well-designed, prospective longitudinal studies would help provide better guidance. In my own practice (A.G.L.) and as described by my esteemed colleagues, I have patients who did not meet the modified Dandy criteria for IIH. Some patients could not have MRI (e.g., pacemaker or other ferromagnetic contraindication or severe obesity) while other patients could not or would not have an LP. These patients I have documented as having “presumed IIH” in contrast to other patients who I can confidently document as having “IIH by modified Dandy criteria.” Both Dr. G.P.V.S. and I agree that the current state of literature is insufficient to provide a definitive evidence-based answer to this controversy, and it is our intention to generate discussion rather than to provide a firm opinion on the subject. REFERENCES 15. Beal JC. Increased intracranial pressure in the setting of Enterovirus and other viral meningitides. Neurol Res Int. 2017;2017:2854043. 16. Espino Barros Palau A, Morgan ML, Foroozan R, Lee AG. Neuro-ophthalmic presentations and treatment of Cryptococcal meningitis-related increased intracranial pressure. Can J Ophthalmol. 2014;49:473–477. 17. Alqahtani AM, Alsaaran ZF, AlOtaibi NH, Barry M, AlJerian K, Alanazy MH, Muayqil TA. Acute HIV infection masquerading as idiopathic intracranial hypertension: a case report and literature review. Case Rep Neurol. 2020;12:56–62. 18. Ezequiel M, Teixeira AT, Brito MJ, Luís C. Pseudotumor cerebri as the presentation of Lyme disease in a non-endemic area. BMJ Case Rep. 2018;2018:bcr–2017-222976. 19. Smith HZ, Paguia R, Horne J, Velagapudi M. A case report of human herpesvirus-6 (HHV-6) meningitis masquerading as idiopathic intracranial hypertension in an immunocompetent patient. Cureus. 2019;11:e4636. 20. Sharma GR, Aryal S, Joshi S. Lower thoracic schwannoma presenting as pseudotumor cerebri: a case report. Br J Neurosurg. 2020. Epub ahead of print. 21. Hu W, Wang C, Wu Q, Chen Y, Gao W, Ying G, Zhu Y, Yan W. Intracranial hypertension due to spinal cord tumor misdiagnosed as pseudotumor cerebri syndrome: case report. BMC Neurol. 2020;20:420. 22. Grixti A, Bonello M, Silver N, Noonan C, Ziahosseini K. Bilateral optic disc edema as a presentation of an obstructing spinal plasmacytoma. Eur J Ophthalmol. 2016;26:32–34. 23. Stefanelli A, Acharya S, Sabourin V, Ghosh R, Farrell C. Atypical presentation of spinal intramedullary astrocytoma in a patient presenting with isolated signs of intracranial hypertension. Spinal Cord Ser Cases. 2020;6:20 24. Andugulapati SS, Chheda A, Desai K, Ravat SH. Diagnostic challenges in neoplastic meningitis presenting as intracranial hypertension. BMJ Case Rep. 2021;14. 25. Ahmed RM, King J, Gibson J, Buckland ME, Gupta R, Gonzales M, Halmagyi GM. Spinal leptomeningeal lymphoma presenting as pseudotumor syndrome. J Neuroophthalmol. 2013;33:13– 16. 26. DeBusk A, Subramanian PS, Scannell Bryan M, Moster ML, Calvert PC, Frohman LP. Mismatch in supply and demand for neuro-ophthalmic care. J Neuroophthalmol. 2021. Epub ahead of print. 27. Bidot S, Saindane AM, Peragallo JH, Bruce BB, Newman NJ, Biousse V. Brain imaging in idiopathic intracranial hypertension. J Neuroophthalmol. 2015;35:400–411. 28. Chen BS, Meyer BI, Saindane AM, Bruce BB, Newman NJ, Biousse V. Prevalence of incidentally detected signs of intracranial hypertension on magnetic resonance imaging and their association with papilledema. JAMA Neurol. 2021;78:718–725. 1. Vosoughi AR, Margolin E, Micieli JA. Can lumbar puncture be safely deferred in patients with mild presumed idiopathic intracranial hypertension?. J Neuroophthalmol. 2021. In press. 2. Margolis MS, DeBusk A, Moster ML, Falardeau J, Eggenberger E, Sergott RC, Van Stavern GP. Lumbar puncture for diagnosis of idiopathic intracranial hypertension in typical patients.J Neuroophthalmol., 2021;41:XXX–XXX. 3. Fisayo A, Bruce BB, Newman NJ, Biousse V. Overdiagnosis of idiopathic intracranial hypertension. Neurology. 2016;86:341–350. 4. Stunkel L, Sharma RA, Mackay DD, Wilson B, Van Stavern GP, Newman NJ, Biousse V. Patient harm due to diagnostic error of neuro-ophthalmologic conditions. Ophthalmology. 2021. Epub ahead of print. 5. Evans RW. Complications of lumbar puncture. Neurol Clin. 1998;16:83–105. 6. Bahnasy WS, El-Heneedy YAE, Elhassanien MEM, Sharaf AF, Khalid HA. Neuro-ophthalmological biomarkers of visual outcome in newly diagnosed idiopathic intracranial hypertension. Egypt J Neurol Psychiatry Neurosurg. 2019;55:26. 7. Friedman DI, Quiros PA, Subramanian PS, Mejico LJ, Gao S, McDermott M, Wall M. Headache in idiopathic intracranial hypertension: findings from the idiopathic intracranial hypertension treatment trial. Headache. 2017;57:1195–1205. 8. Baer ET. Post-dural puncture bacterial meningitis. Anesthesiology. 2006;105:381–393. 9. Lee SCM, Lueck CJ. Cerebrospinal fluid pressure in adults. J Neuroophthalmol. 2014;34:278–283. 10. Bellamkonda VR, Wright TC, Lohse CM, Keaveny VR, Funk EC, Olson MD, Laack TA. Effect of spinal needle characteristics on measurement of spinal canal opening pressure. Am J Emerg Med. 2017;35:769–772. 11. Mikkilineni S, Trobe JD, Cornblath WT, de Lott L. Visual field mean deviation at diagnosis of idiopathic intracranial hypertension predicts visual outcome. J Neuroophthalmol. 2019;39:186–190. 12. Al-Hashel JY, Ismail II, Ibrahim M, John JK, Husain F, Kamel WA, Behbehani R, Ahmed SF. Demographics, clinical characteristics, and management of idiopathic intracranial hypertension in Kuwait: a single-center experience. Front Neurol. 2020;11:672. 13. Wall M, Kupersmith MJ, Kieburtz KD, Corbett JJ, Feldon SE, Friedman DI, Katz DM, Keltner JL, Schron EB, McDermott MP. The idiopathic intracranial hypertension treatment trial: clinical profile at baseline. JAMA Neurol. 2014;71:693–701. 14. Riggeal BD, Bruce BB, Saindane AM, Ridha MA, Kelly LP, Newman NJ, Biousse V. Clinical course of idiopathic intracranial hypertension with transverse sinus stenosis. Neurology. 2013;80:289–295. 384 Moss et al: J Neuro-Ophthalmol 2021; 41: 379-384 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.