The Increasing Burden of Emergency Department and Inpatient Consultations for "Papilledema".

BACKGROUND: Increasing incidence of idiopathic intracranial hypertension (IIH), overreported radiologic signs of intracranial hypertension, difficult access to outpatient neuro-ophthalmology services, poor insurance coverage, and medicolegal concerns have lowered the threshold for emergency department (ED) visits for "papilledema." Our objective was to examine referral patterns and outcomes of neuro-ophthalmology ED and inpatient consultations for concern for papilledema. METHODS: At one university-based quaternary care center, all adults referred for "papilledema" over one year underwent a standardized ED "papilledema protocol." We collected patient demographics, final diagnoses, and referral patterns. RESULTS: Over 1 year, 153 consecutive patients were referred for concern for papilledema. After papilledema protocol, 89 of 153 patients (58%) had bilateral optic disc edema, among whom 89% (79/89) had papilledema (intracranial hypertension). Of the 38 of 153 (25%) consultations for suspected disorder of intracranial pressure without previous fundus examination (Group 1), 74% (28/38) did not have optic disc edema, 21% (8/38) had papilledema, and 5% (2/38) had other causes of bilateral disc edema. Of the 89 of 153 (58%) consultations for presumed papilledema seen on fundus examination (Group 2), 58% (66/89) had confirmed papilledema, 17% (15/89) had pseudopapilledema, and 9% (8/89) had other causes of bilateral optic disc edema. Of the 26 of 153 (17%) patients with known IIH (Group 3), 5 had papilledema and 4 required urgent intervention. The most common diagnosis was IIH (58/79). Compared with IIH, patients with secondary causes of intracranial hypertension were older (P = 0.002), men (P < 0.001), not obese (P < 0.001), and more likely to have neurologic symptoms (P = 0.002). CONCLUSION: Inpatient and ED consultations for "papilledema" are increasing. Of the 153 ED and inpatient neuro-ophthalmology consultations seen for "papilledema" over 1 year, one-third of patients with optic disc edema of unknown cause before presentation to our ED had new vision- or life-threatening disease, supporting the need for prompt identification and evaluation of optic disc edema in the ED. In the face of limited access to neuro-ophthalmologists, this study supports the need for emergency department access to expert eye-care evaluation or ocular fundus camera for prompt identification of optic disc edema and standardized evaluation for neurologic emergencies.

The BONSAI (Brain and Optic Nerve Study with Artificial Intelligence) deep learning system can accurately identify pediatric papilledema on standard ocular fundus photographs.

BACKGROUND: Pediatric papilledema often reflects an underlying severe neurologic disorder and may be difficult to appreciate, especially in young children. Ocular fundus photographs are easy to obtain even in young children and in nonophthalmology settings. The aim of our study was to ascertain whether an improved deep-learning system (DLS), previously validated in adults, can accurately identify papilledema and other optic disk abnormalities in children. METHODS: The DLS was tested on mydriatic fundus photographs obtained in a multiethnic pediatric population (<17 years) from three centers (Atlanta-USA; Bucharest-Romania; Singapore). The DLS's multiclass classification accuracy (ie, normal optic disk, papilledema, disks with other abnormality) was calculated, and the DLS's performance to specifically detect papilledema and normal disks was evaluated in a one-vs-rest strategy using the AUC, sensitivity and specificity, with reference to expert neuro-ophthalmologists. RESULTS: External testing was performed on 898 fundus photographs: 447 patients; mean age, 10.33 (231 patients ≤10 years of age; 216, 11-16 years); 558 normal disks, 254 papilledema, 86 other disk abnormalities. Overall multiclass accuracy of the DLS was 89.6% (range, 87.8%-91.6%). The DLS successfully distinguished "normal" from "abnormal" optic disks (AUC 0.99 [0.98-0.99]; sensitivity, 87.3% [84.9%-89.8%]; specificity, 98.5% [97.6%-99.6%]), and "papilledema" from "normal and other" (AUC 0.99 [0.98-1.0]; sensitivity, 98.0% [96.8%-99.4%]; specificity, 94.1% (92.4%-95.9%)]. CONCLUSIONS: Our DLS reliably distinguished papilledema from normal optic disks and other disk abnormalities in children, suggesting it could be utilized as a diagnostic aid for the assessment of optic nerve head appearance in the pediatric age group.

Outcomes of Strabismus Surgery Following Teprotumumab Therapy.

PURPOSE: To investigate the results of patients undergoing surgical treatment for strabismic diplopia in thyroid eye disease (TED) following teprotumumab. DESIGN: Multicenter, retrospective, case series. METHODS: We report 28 patients who underwent extraocular muscle surgery for strabismic diplopia after treatment with teprotumumab at 7 different academic centers. Elapsed time from last teprotumumab dose to the date of surgery, previous orbital decompression, primary preoperative horizontal and vertical deviation, surgical procedure, and 2-month postoperative results were collected from the patient records. RESULTS: Sixteen (57%) patients were diplopia-free after 1 surgery. Three (11%) chose prism spectacles to correct residual diplopia, 2 (7%) used compensatory head posture to resolve diplopia, and 1 (4%) had intermittent diplopia and was functionally improved (choosing no prisms or further surgery). These were considered treatment successes. Three (11%) patients required reoperation, and all were diplopia-free after their second procedure. CONCLUSIONS: Most patients requiring surgery for strabismic diplopia following teprotumumab achieve good outcomes with success rates comparable to series published before the availability of teprotumumab.

Volumetric Analysis of Spheno-Orbital Meningiomas: Prognostic Correlation and a Compartmentalized Approach.

BACKGROUND AND OBJECTIVES: Spheno-orbital meningiomas arise from the arachnoid villi cap cells at the sphenoid ridge and have the ability to spread through soft tissue extension and cranial bone invasion. Owing to their orbital hyperostosis and intraorbital soft tissue extension, they commonly present with ophthalmologic manifestations. This study aims to investigate the correlation between tumor volume with the presenting symptoms and postoperative outcomes. METHODS: This retrospective study analyzed patients who underwent surgical resection of spheno-orbital meningiomas. Tumor volumes in different compartments were measured using preoperative and postoperative imaging. Linear and logistic regression analyses were used to identify correlations between tumor volumes and presenting symptoms preoperatively and postoperative outcomes. RESULTS: Sixty-six patients were included in this study, of whom 86.4% had proptosis, 80.3% had decreased visual acuity (VA), 30.3% had visual field defects, and 13.6% had periorbital edema. Preoperatively, proptosis linearly correlated with intraosseous tumor volume (coefficient = 0.6, P < .001), while the decrease in baseline VA correlated with the intraorbital tumor volume (coefficient = 0.3, P = .01). The odds of periorbital edema were found to increase with an increase in intraosseous tumor volume with an adjusted odds ratio of 1.4 (95% CI, 1.1-1.7, P = .003), while the odds of visual field defects were found to increase with an increase in intraorbital tumor volume with an adjusted odds ratio of 2.7 (95% CI, 1.3-5.6, P = .01). Postoperatively, the volume of intraosseous tumor resected linearly correlated with the improvement in proptosis (coefficient = 0.7, P < .001), while the volume of intraorbital tumor resected linearly correlated with improvement in VA (coefficient = 0.5, P < .001) and with a larger effect size in patients presenting with moderate-to-severe decrease in VA preoperatively (coefficient = 0.8). CONCLUSION: Underscoring the importance of each tumor compartment relative to the patient's symptomatology serves as a valuable guide in implementing a compartmentalized resection approach tailored to the surgical objectives.

Visual outcomes after bevacizumab-based therapy for optic pathway glioma.

In optic pathway glioma (OPG), bevacizumab-based therapy (BBT) has promising effects on radiographic tumor burden, but the impact on vision is less clear. This single-institution study characterized visual acuity (VA) and visual field (VF) outcomes in 17 pediatric OPG patients treated with BBT. VA was stable or improved in 14 patients. Nine patients had evaluable VF data, six of whom experienced stability or improvement. Among six patients with vision deterioration as a treatment indication, stable or improved was observed for both VA and VF in five patients. In summary, BBT was associated with favorable visual outcomes in this cohort of patients with OPG.

Neuro-ophthalmology Emergency Department and Inpatient Consultations at a Large Academic Referral Center.

PURPOSE: Prompt neuro-ophthalmology consultation prevents diagnostic errors and improves patient outcomes. The scarcity of neuro-ophthalmologists means that the increasing outpatient demand cannot be met, prompting many emergency department (ED) referrals by non-neuro-ophthalmologists. We describe our quaternary care institution's ED and inpatient neuro-ophthalmology consultation patterns and patient outcomes. DESIGN: Prospective observational study. PARTICIPANTS: Consecutive neuro-ophthalmology ED and inpatient consultation requests over 1 year. METHODS: We collected patient demographics, distance traveled, insurance status, referring provider details, consultation question, final diagnosis, complexity of consultation, time of consultation, and need for outpatient follow-up. MAIN OUTCOME MEASURES: Consultation patterns and diagnoses, complexity, and follow-up. RESULTS: Of 494 consecutive adult ED and inpatient neuro-ophthalmology consultations requested over 1 year, 241 of 494 consultations (49%) occurred at night or during weekends. Of ED consultations (322 of 494 [65%]), 127 of 322 consultations (39%) occurred during weekdays, 126 of 322 consultations (39%) occurred on weeknights, and 69 of 322 consultations (22%) occurred on weekends or holidays. Of 322 ED consultations, 225 of 322 consultations (70%) were patients who initially sought treatment in the ED with a neuro-ophthalmic chief symptom. Of the 196 patients sent to the ED by a health care professional, 148 patients (148/196 [76%]) were referred by eye care specialists (74 optometrists and 74 ophthalmologists). The most common ED referral questions were for papilledema (75 of 322 [23%]) and vision loss (72 of 322 [22%]). A total of 219 of 322 patients (68%) received a final active neuro-ophthalmic diagnosis, 222 of 322 patients (69%) were cases of high or very high complexity, and 143 of 322 patients (44%) required admission. Inpatient consultations (n = 172) were requested most frequently by hospitalists, including neurologists (71 of 172 [41%]) and oncologists (20 of 172 [12%]) for vision loss (43 of 172 [25%]) and eye movement disorders (36 of 172 [21%]) and by neurosurgeons (58 of 172 [33%]) for examination for mass or a preoperative evaluation (19 of 172 [11%]). An active neuro-ophthalmic diagnosis was confirmed in 67% of patients (116 of 172). Outpatient neuro-ophthalmology follow-up was required for 291 of 494 patients (59%). CONCLUSIONS: Neuro-ophthalmology consultations are critical to the diagnosis and management in the hospital setting. In the face of a critical shortage of neuro-ophthalmologists, this study highlights the need for technological and diagnostic aids for greater outpatient access. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Nonneurologic causes of binocular diplopia for the neurologist.

PURPOSE OF REVIEW: To review several etiologies of nonneurologic diplopia that the neurologist should be familiar with. The pathophysiology, clinical presentation, neuroimaging findings, and treatment options are briefly summarized for each condition. RECENT FINDINGS: Certain etiologies for diplopia can be associated with life-threatening neurologic conditions and should be investigated thoroughly for proper localization and immediate management of the underlying disease. However, nonneurological causes of binocular diplopia are very common and disabling, but are often nonemergent and may not require in-depth investigation or neuroimaging. Some of the etiologies of nonneurologic diplopia mimic cranial nerve palsies, making them confusing to evaluate when the physician is not familiar with these etiologies. Unfamiliarity with these diagnoses can lead to unnecessary neuroimaging, inefficient utilization of medical resources, and undue alarm to the patient. Recent advances in clinical diagnostic tools and neuroimaging have clarified our understanding of the diverse underlying mechanisms of nonneurologic binocular diplopia. SUMMARY: Diplopia can be a difficult symptom for the neurologist to evaluate. A systematic approach to the evaluation of diplopia can help establish the urgency and necessity of an extensive workup.This review will help to familiarize the neurologist with nonneurological causes of binocular diplopia, minimize expensive and unnecessary evaluations, and reassure patients and physicians alike.

Variation of the modified Nishida procedure for traumatic rupture of inferior rectus muscle.

We present a case of traumatic rupture of the inferior rectus muscle associated with an inferior orbital floor fracture. Initial examination revealed a left hypertropia with severe limitation of infraduction of the left eye past the midline. The inferior rectus muscle could not be retrieved after an anterior orbitotomy. The patient underwent a variation of the modified Nishida procedure 3 months later. At 3 months' follow-up, he had a moderate undercorrection at distance and near and a mild improvement in infraduction. He was able to fuse with prism in his glasses. Traumatic rupture of the inferior rectus muscle is an uncommon and difficult problem to treat; the variation of the modified Nishida procedure presented here offered a feasible surgical option in this case.

Strabismus surgery outcomes for internuclear ophthalmoplegia with exotropia.

Exotropia (XT) in internuclear ophthalmoplegia (INO) is a difficult problem to treat. The purpose of this study is to describe surgical approaches in treating INO and glean insight into various pre-operative factors that may affect outcomes for XT in INO. We conducted a retrospective review from 1 January 1995 - 5 January 2021 and identified seven patients with INO who underwent strabismus surgery for XT. Patient age, sex, etiology of INO, pre-operative alignment and sensorimotor exam, presence of diplopia, surgery performed, subsequent surgeries, use of adjustable sutures, post-operative alignment, presence of post-operative diplopia, presence of post-operative diplopia with use of prism correction, and length of follow-up were all collected. Initial surgeries undertaken included unilateral medial rectus (MR) plication and lateral rectus (LR) recession, bilateral medial rectus (MR) plications or resections, or bilateral MR plications combined with either unilateral or bilateral LR recessions. Chart review yielded ten charts, however two were excluded due to manifest esotropia (ET), and one was excluded due to incomplete records. Seven total patients were used in final analysis. The cohort age range was from 29 to 79 years. Pre-operative horizontal distance alignment ranged from 35 to 95 XT with an average exodeviation of 67.8 ± 22.6 prism diopters (PD). Horizontal adduction deficit ranged from -1 to -4 and was present bilaterally in all patients. A variety of initial surgical approaches were undertaken. After two muscle surgeries, distance deviation had an average change of 57.3 PD. After three muscle surgeries, distance deviation had an average change of 75 PD. After four muscle surgeries, distance deviation had an average change of 60 PD. Three patients required additional surgery for XT. Time to follow-up ranged from 1 to 58 months. Horizontal distance alignment in primary gaze at latest follow-up ranged from 30 ET to 30 XT with an average of 0 (orthotropia) ± 16.0 PD. One patient had a consecutive esotropia of 30 PD, one had a persistent exotropia of 30 PD, and five patients were orthotropic at distance. All patients reported relief of diplopia in primary gaze at near and distance either with or without use of prism. Horizontal ductions improved to some degree in all patients. Horizontal rectus surgery can treat many cases of XT in INO. Surgeons should consider INO etiology and concomitant vertical deviations when considering surgery. The degree of pre-operative adduction limitation is another important factor, though did not always dictate final motor and sensory outcomes.

Chronic recurrent multifocal osteomyelitis causing optic neuropathy.

We present the case of an 8-year-old girl with chronic recurrent multifocal osteomyelitis (CRMO) involving the orbit and facial bone and causing left optic neuropathy. She presented with intermittent left periorbital swelling and a history of CRMO diagnosed 5 years earlier. Her disease responded well to adalimumab; however, delayed presentation resulted in permanent unilateral optic nerve atrophy and reduced vision. Orbital inflammatory disease is a rare manifestation of CRMO, and early recognition of the disease and treatment may prevent irreversible vision loss.

Vision-related quality-of-life in pediatric primary brain tumor patients.

PURPOSE: Brain tumors are the leading cause of death from childhood cancer. Although overall survival has improved due to earlier detection, better therapies, and improved surveillance, visual dysfunction and impaired vision-related quality-of-life (VR-QOL) are often unrecognized in children. This project investigated VR-QOL in pediatric brain tumor patients. METHODS: We evaluated visual impairment and quality-of-life (QOL) in a quality improvement project at one tertiary care center. Patients ≤ 18, greater than 6 months from diagnosis of brain tumor, excluding intrinsic anterior visual pathway tumors, underwent standardized neuro-ophthalmologic examination. Health-related QOL (HR-QOL) (PedsQL Brain Tumor Module) and VR-QOL questionnaires [CVFQ (Children's Visual Function Questionnaire) in children < 8, and EYE-Q in children 8-18] were obtained from patients and parents. RESULTS: Among 77 patients, craniopharyngiomas (n = 16, 21%) and astrocytomas (n = 15, 20%) were the most common tumors. Among 44/77 (57%) visually impaired children, 7 (16%) were legally blind. Eye-Q median score was 3.40 (interquartile range 3.00-3.75), worse than average scores for normal children. Eye-Q score decreased 0.12 with every 0.1 increase in logMAR visual acuity (p < 0.001). Patients who were legally blind had a significantly lower Eye-Q score than those who were not [0.70 vs. 3.44 (p < 0.001)]. Cognitive HR-QOL scores decreased 1.3 for every 0.1 increase in logMAR visual acuity (p = 0.02). CONCLUSIONS: Pediatric brain tumor patients' vision, HR-QOL, and VR-QOL were often severely affected even when tumors were considered cured. Visual acuity and legal blindness correlated with VR-QOL. Systematic neuro-ophthalmologic examinations in pediatric primary brain tumor patients are necessary to facilitate early preventative and corrective ophthalmologic interventions.

A prospective study of treatments for adult-onset divergence insufficiency-type esotropia.

PURPOSE: To describe 10-week and 12-month outcomes following treatment for divergence insufficiency-type esotropia in adults. METHODS: In this prospective observational study, 110 adults with divergence insufficiency-type esotropia, with a distance esodeviation measuring 2Δ to 30Δ and at least 25% larger at distance than near, and binocular diplopia present at least "sometimes" at distance, were enrolled at 28 sites when initiating new treatment. Surgery, prism, or divergence exercises/therapy were chosen at the investigator's discretion. Diplopia was assessed at enrollment and at 10-week and 12-month outcome examinations using a standardized diplopia questionnaire (DQ). Success was defined as DQ responses of "rarely" or "never" when looking straight ahead in the distance, with no alternative treatment initiated. RESULTS: Of the 110 participants, 32 (29%) were prescribed base-out prism; none had received prior treatment for esotropia. Success criteria were met by 22 of 30 at 10 weeks (73%; 95% CI, 54%-88%) and by 16 of 26 at 12 months (62%; 95% CI, 41%-80%). For the 76 (68%) who underwent strabismus surgery (82% of whom had been previously treated with prism), success criteria were met by 69 of 74 at 10 weeks (93%; 95% CI, 85%-98%) and by 57 of 72 at 12 months (79%; 95% CI, 68%-88%). CONCLUSIONS: In this study cohort, both base-out prism as initial therapy and strabismus surgery (usually following prism) were successful in treating diplopia for most adults with divergence insufficiency-type esotropia when assessed during the first year of follow-up.

Very Poor Visual Acuity in Non-Arteritic Anterior Ischaemic Optic Neuropathy.

Very poor (hand motion or worse) visual acuity at presentation is highly unusual in non-arteritic anterior ischaemic optic neuropathy. We retrospectively reviewed the medical records of 151 consecutive non-arteritic anterior ischaemic optic neuropathy patients seen at our institution between July 2014 and April 2016 to evaluate the frequency and characteristics of patients with very poor visual acuity in non-arteritic anterior ischaemic optic neuropathy. Hand motion or worse visual acuity was documented in 17 patients (11%); all patients had at least one vascular risk factor and 14 (82%) had at least two vascular risk factors. Although severe vision loss at presentation does occur in non-arteritic anterior ischaemic optic neuropathy, an extensive workup should be obtained to rule out another cause, especially arteritic anterior ischaemic optic neuropathy.

Clinical and demographic differences between idiopathic intracranial hypertension patients with mild and severe papilledema.

PURPOSE: The purpose of this study was to evaluate whether papilledema severity is associated with specific demographic or clinical factors in patients with idiopathic intracranial hypertension (IIH). MATERIALS AND METHODS: A retrospective cohort study of consecutive IIH patients seen at one tertiary care institution between 1989 and March 31, 2017 was performed. IIH patients were classified as mild (Frisén Grade 1 or 2) or severe (Frisén Grade 4 or 5) based on grading of fundus photographs obtained at first presentation. Demographic and clinical variables including age, body mass index (BMI), gender, visual acuity, Humphrey visual field mean deviation, and cerebrospinal fluid (CSF) opening pressure were extracted from patient medical records for statistical analyses. RESULTS: A total of 239 patients were included in the study: 152 with mild papilledema and 87 with severe papilledema. There was no difference in age, race, BMI, or male gender between the mild and severe papilledema groups. CSF opening pressure was significantly higher in the severe papilledema group (41.89 cm of water vs. 33.69, 95% confidence interval [CI]: -10.79--5.62, P < 0.0001). There was a significant difference in the Humphrey mean deviation (-6.38 dB compared to - 3.25 dB, 95% CI: -4.82--1.44 dB, P < 0.001) and average logarithm of the minimum angle of resolution visual acuity at final follow-up (0.21 vs. 0.045, 95% CI: -0.299--0.040 , P = 0.01). CONCLUSION: Age, race, sex, and BMI were similar in IIH patients with mild versus severe papilledema, emphasizing the importance of a dilated fundus examination to reliably stratify patients. Patients with severe papilledema are at higher risk of visual acuity and visual field loss at final follow-up.

Optic nerve head plasmacytoma as a manifestation of multiple myeloma.

Extramedullary disease in multiple myeloma is uncommon and associated with a poorer prognosis. Extramedullary disease involving the orbit is even more unusual, with optic nerve involvement being rare. We describe an optic nerve head plasmacytoma in a 45-year-old female in the setting of systemic relapsed, refractory IgA kappa multiple myeloma. The case highlights the importance of keeping extramedullary disease spread in the differential for vision loss in a patient with a history of multiple myeloma. In addition, it describes an unusual location for presentation of extramedullary disease, the optic nerve head, which has rarely been described.

Unilateral Isolated Paucisymptomatic Optic Disc Edema.

BACKGROUND: Unilateral isolated optic disc edema (UIODE) represents a challenging clinical presentation that frequently precipitates an extensive diagnostic work-up. Patients without an apparent diagnosis despite appropriate investigations are often categorized as having "papillophlebitis," an entity that is poorly defined in the existing literature. Our aim was to describe the characteristics of a series of patients with paucisymptomatic UIODE, determine the optimal diagnostic approach to such cases, and clarify the clinical features of presumed papillophlebitis. METHODS: We retrospectively identified 29 patients with UIODE who were seen by neuro-ophthalmologists at a single center between 2005 and 2019. Each patient presented with isolated, unilateral disc edema that was either entirely asymptomatic or associated with minimal visual symptoms. Patients underwent a comprehensive neuro-ophthalmic evaluation and several ophthalmic and systemic investigations. Data from the initial visit and all subsequent clinical visits were collected, including patient demographics, examination findings, and details of the diagnostic work-up. RESULTS: Our 29 patients with UIODE were found to have a variety of underlying diagnoses including unilateral papilledema due to idiopathic intracranial hypertension (10 patients), optic nerve sheath meningioma (5), incipient nonarteritic anterior ischemic neuropathy (4), vitreopapillary traction (3), orbital masses (2), a peripapillary choroidal neovascular membrane (1), and presumed papillophlebitis (4). The duration of disc edema varied considerably based on the etiology, but most patients had favorable visual outcomes. CONCLUSIONS: A systematic approach to the evaluation of UIODE, combined with long-term follow-up, led to a definite diagnosis in a majority of patients, with only 4 patients presumed to have papillophlebitis, a diagnosis the actual existence of which remains controversial.

Spontaneous Skull Base Cerebrospinal Fluid Leaks and Their Relationship to Idiopathic Intracranial Hypertension.

BACKGROUND: The association between spontaneous skull base cerebrospinal fluid (CSF) leaks and idiopathic intracranial hypertension (IIH) has been suggested, but its significance remains unclear. OBJECTIVE: To estimate the prevalence of IIH in spontaneous skull base CSF leak patients. METHODS: Systematic collection of demographics, neuro-ophthalmic and magnetic resonance imaging evaluation of spontaneous skull base CSF leak patients seen pre- and post-leak repair in one neuro-ophthalmology service. Patients with preexisting IIH were diagnosed with definite IIH if adequate documentation was provided; otherwise, they were categorized with presumed IIH. Classic radiographic signs of intracranial hypertension and bilateral transverse venous sinus stenosis were recorded. RESULTS: Thirty six patients were included (age [interquartile range]: 50 [45;54] years; 94% women; body mass index: 36.8 [30.5;39.9] kg/m2), among whom six (16.7%, [95% confidence interval, CI]: [6.4;32.8]) had a preexisting diagnosis of definite or presumed IIH. Of the remaining 30 patients, four (13.3%, 95%CI: [3.8;30.7]) had optic nerve head changes suggesting previously undiagnosed IIH, while one was newly diagnosed with definite IIH at initial consultation. One out of 29 patients with normal findings of the optic nerve head at presentation developed new onset papilledema following surgery (3.4%, 95%CI: [0.1;17.8]) and was ultimately diagnosed with definite IIH. Overall, the prevalence of definite IIH was 19.4% (95%CI: [8.2;36.0]). CONCLUSION: Striking demographic overlap exists between IIH patients and those with spontaneous CSF leak. Definite IIH was present in approximately 20% of our patients. However, its true prevalence is likely higher than identified by using classic criteria. We therefore hypothesize that an active CSF leak serves as an auto-diversion for CSF, thereby "treating" the intracranial hypertension and eliminating characteristic signs and symptoms at initial presentation.