Idiopathic Intracranial Hypertension: Incidental Discovery Versus Symptomatic Presentation

Background: We aim to compare the clinical characteristics, disease course and visual outcomes between Canadian patients with idiopathic intracranial hypertension (IIH) who were incidentally discovered and those who sought care due to symptoms of IIH. Methods: Retrospective chart review of consecutive IIH patients conducted at tertiary neuro-ophthalmology clinics. Patients were divided into Group 1 (incidentally discovered disease) and Group 2 (patients seeking medical care due to symptoms of intracranial hypertension). Results: One hundred eighty-six patients were included in the study; of which, 75 (40.3%; Group-1) were incidentally discovered and 111 presented due to symptoms of IIH (Group-2). There were no differences in proportion of females (P = 0.101), age (P = 0.450), body mass index (P = 0.386), MRI findings of empty or partially empty sella (P = 0.41), and sella grade (P = 0.704). Group-1 patients were less likely to have experienced headache (P = 0.001), transient visual obscurations (P < 0.001), and diplopia (P = 0.026) at presentation. Group-1 patients were less likely to receive medical (P < 0.001) and surgical (P = 0.004) treatment. There was no difference in proportion of patients who lost weight between the groups (P = 0.848). At baseline, Group-1 patients exhibited better visual acuity (P = 0.001), Humphrey mean deviation (P < 0.001) and retinal nerve fiber layer thickness (P < 0.001). Group-1 patients continued to have better visual acuity (P = 0.002) and Humphrey mean deviation (P < 0.001) at final follow-up. Conclusions: A significant portion of IIH patients were incidentally discovered. This group exhibited a favorable prognosis and only a minority of these patients required treatment. The way in which patients enter the medical system may be a valuable way to risk stratify IIH patients.

Original Contribution Section Editors: Clare Fraser, MD Susan Mollan, MD Idiopathic Intracranial Hypertension: Incidental Discovery Versus Symptomatic Presentation Amir R. Vosoughi, BSc, Edward A. Margolin, MD, Jonathan A. Micieli, MD, CM Background: We aim to compare the clinical characteristics, disease course and visual outcomes between Canadian patients with idiopathic intracranial hypertension (IIH) who were incidentally discovered and those who sought care due to symptoms of IIH. Methods: Retrospective chart review of consecutive IIH patients conducted at tertiary neuro-ophthalmology clinics. Patients were divided into Group 1 (incidentally discovered disease) and Group 2 (patients seeking medical care due to symptoms of intracranial hypertension). Results: One hundred eighty-six patients were included in the study; of which, 75 (40.3%; Group-1) were incidentally discovered and 111 presented due to symptoms of IIH (Group-2). There were no differences in proportion of females (P = 0.101), age (P = 0.450), body mass index (P = 0.386), MRI findings of empty or partially empty sella (P = 0.41), and sella grade (P = 0.704). Group-1 patients were less likely to have experienced headache (P = 0.001), transient visual obscurations (P , 0.001), and diplopia (P = 0.026) at presentation. Group-1 patients were less likely to receive medical (P , 0.001) and surgical (P = 0.004) treatment. There was no difference in proportion of patients who lost weight between the groups (P = 0.848). At baseline, Group-1 patients exhibited better visual acuity (P = 0.001), Humphrey mean deviation (P , 0.001) and retinal nerve fiber layer thickness (P , 0.001). Group-1 patients continued to have better visual acuity (P = 0.002) and Humphrey mean deviation (P , 0.001) at final follow-up. Conclusions: A significant portion of IIH patients were incidentally discovered. This group exhibited a favorable prognosis and only a minority of these patients required Max Rady College of Medicine (ARV), Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada; Department of Ophthalmology and Vision Sciences (EAM JAM), University of Toronto, Toronto, Canada; Division of Neurology (EAM Department of Medicine, University of Toronto, Canada; and Kensington Vision and Research Centre (JAM), Toronto, Canada The authors report no conflicts of interest Address correspondence to Jonathan A. Micieli, MD, CM, Kensington Vision and Research Centre, 501-340 College Street, Toronto, ON M5T3A9, Canada; E-mail: [e-mail] Vosoughi et al: J Neuro-Ophthalmol 2022; 42: 187-191 treatment. The way in which patients enter the medical system may be a valuable way to risk stratify IIH patients. Journal of Neuro-Ophthalmology 2022;42:187–191 doi: 10.1097/WNO.0000000000001475 © 2022 by North American Neuro-Ophthalmology Society I diopathic intracranial hypertension (IIH) is a condition characterized by signs and symptoms of raised intracranial pressure in the absence of an identifiable cause (1). Overweight women of childbearing age tend to be most commonly affected, and the incidence of IIH has increased in line with the obesity epidemic (2). The most common symptoms experienced by patients with IIH include headache, most commonly a migraine-like phenotype, followed by transient visual obscurations, pulsatile tinnitus, and diplopia (3,4). Permanent blindness related to papilledema is a feared complication of IIH, and treatment involves medical or surgical interventions to lower the intracranial pressure (1). The way in which IIH patients enter the medical system has not been well studied. Patients may become symptomatic from intracranial hypertension and seek medical attention due to worsening headaches, pulsatile tinnitus, or vision loss from papilledema. As primary headache disorders are common in the general population, patients may not necessarily seek medical attention even if their headache characteristics change. Furthermore, headaches in patients with IIH typically display features that overlap with primary headaches, often resembling a migrainous phenotype (4). Patients with IIH may also be relatively asymptomatic, and papilledema may be incidentally discovered by eye care providers when the patient attends a routine eye examination or has an unrelated eye issue (5,6). The goal of this study was to determine the proportion of patients who have incidentally discovered papilledema due to IIH and to compare this group with IIH patients who sought medical care due to symptoms of intracranial hypertension. 187 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution METHODS This was a retrospective chart review of consecutive patients with IIH presenting to tertiary neuro-ophthalmology clinics in Toronto, Canada from July 2017– July 2020. Research ethics board approval was obtained by the University of Toronto Research Ethics Board. Patients were included in the study if they were diagnosed with IIH according to published diagnostic criteria (7) or presumed IIH in which they met the criteria but lumbar puncture (LP) was deferred. Patients on medications known to cause intracranial hypertension were excluded. Patients were categorized into Group 1 (incidentally discovered disease) or Group 2 (patients seeking medical care due to a symptom of intracranial hypertension such as headache, pulsatile tinnitus, vision loss, or diplopia). Incidentally discovered disease was defined as papilledema discovered on an eye examination performed for an unrelated reason, such as a red eye, new refraction, or routine follow-up for another reason. Papilledema was not considered incidental if the patient had previously visited a doctor for headache, pulsatile tinnitus, transient visual obscurations, or vision loss Papilledema was determined by fellowship-trained neuroophthalmologists based on clinical examination and adjunctive imaging, such as fundus autofluorescence, intravenous fluorescein angiography, and enhanced depth imaging optical coherence tomography (OCT), to exclude pseudopapilledema (optic nerve head drusen and congenitally full and elevated optic nerves). The demographic information and clinical information were extracted for each patient. Weight and height were determined based on patient report. As patients with suspected papilledema are routinely asked about symptoms of headaches, pulsatile tinnitus, transient visual obscurations, or diplopia, these data were available for review and extracted. The neuro-ophthalmology examination performed included Snellen visual acuity, Humphrey 24-2 SITA-Fast visual fields, OCT of the retinal nerve fiber layer (RNFL) and macular ganglion cell layer–inner plexiform layer (GCIPL), and biomicroscopic examination of the anterior and posterior pole of the eye. Snellen visual acuity (best corrected with manifest refraction or pinhole) was converted to logarithm of the minimum angle of resolution (logMAR) for analysis, and Humphrey mean deviation (MD) was used for comparison. OCT RNFL and GCIPL were performed with Cirrus HD-OCT 5000 for all patients. T1 midsagittal MRI images were reviewed by the senior author for the presence of an empty or partially empty sella. An empty or partially empty sella was defined as complete or partial CSF filling of the sella turcica associated with the lack of visible pituitary gland on T1 midsagittal MRI image. The severity of the empty sella in each patient was graded from a scale of 1–5 (1 = normal, 2 = mild superior concavity, less than one-third height of the sella turcica, 3 = moderate concavity between one-third and two-third height of the sella turcica, 4 = severe concavity, 188 more than two-third height of the sella turcica, 5=no pituitary tissue visible) (8). Statistical analysis was performed using SPSS (IBM, 2019). Mean and SD were reported for variables analyzed. Comparisons between Group 1 and Group 2 were performed using x2 and Student t-tests with Bonferonni correction. Statistical significance was accepted for P values ,0.05. RESULTS A total of 186 patients (178 women and 8 men) were included in the study with a mean ± SD age of 31.2 ± 10.4 years and body mass index (BMI) of 34.6 ± 7.1 kg/m2. Incidentally discovered papilledema accounted for 75 of all patients (40.3%), which was Group 1, and Group 2 consisted of 111 patients (59.7%). There was no difference in age, BMI, or proportion of females in both groups (Table 1). Patients in Group 1 were less likely to experience headache, transient visual obscurations (TVOs), or diplopia at presentation (Fig. 1). A total of 8 of 75 patients (10.7%) in Group 1 were completely asymptomatic, and all had an OCT-RNFL average thickness less than 200 mm in each eye. The diplopia was related to sixth nerve palsy in Group 2 patients, and all had a limitation of abduction and esodeviation in primary position. In Group 1, the diplopia was found to be related to decompensation of preexisting strabismus and was not related to raised ICP. At presentation, patients in Group 1 had a better logMAR visual acuity (0.03 ± 0.06 vs 0.09 ± 0.27; P = 0.001), Humphrey MD (22.8 ± 3.9 vs 24.4 ± 5.7; P , 0.001), and OCT RNFL average thickness (157.4 ± 69.2 vs 192.3 ± 107.1 mm; P , 0.001). OCT-RNFL thickness was more than 300 mm in at least 1 eye in 5 of 75 (7.0%) Group-1 patients and 20 of 111 (18.0%) Group-2 patients. T1 sagittal MRI images were available for review in 176 patients (72/75 [96.0%] in Group 1 and 104/111 [93.7%] in Group 2) and a partially or empty sella was seen in 160 of 172 patients (93.0%). There was no difference in the presence of an empty or partially empty sella (Group 1, 67/72 [93.2%] vs Group 2, 93/104 [89.4%]; P = 0.41) or the sella grade between the groups (3.2 ± 1.2 vs 3.3 ± 1.2; P = 0.704). There were also similar proportions of patients who had no pituitary tissue visible categorized as Grade 5 (Group 1 14/ 72 [19.4%] and Group 2 16/104 [15.4%]; P = 0.78). Lumbar puncture was performed in more patients in Group 2 (67/111 60.4% vs 21/75, 28.0%; P , 0.001), and Group 2 patients had a higher LP opening pressure (38.3 ± 9.4 vs 33.6 ± 6.8 cmH2O; P = 0.037). More patients in Group 2 were treated medically with acetazolamide (56/111 [50.5%] vs 19/75 [25.3%]; P , 0.001), and no patient in Group 1 underwent surgical treatment. A total of 11 of 111 patients (9.9%) in Group 2 were treated with cerebrospinal fluid shunting. Vosoughi et al: J Neuro-Ophthalmol 2022; 42: 187-191 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution TABLE 1. Patient characteristics in incidentally discovered (Group 1) vs patients seeking care for symptoms of IIH (Group 2) Category N (% of cohort) Female (% female) Age (mean ± SD) BMI LogMAR VA (mean ± SD) OCT RNFL thickness (mean ± SD) Humphrey mean deviation (mean ± SD)) Empty or partially empty sella (%) Sella grade No pituitary tissue visible Incidental Symptomatic P 75 (40.3%) 74 (98.7%) 32.0 ± 11.6 34.0 ± 6.3 0.03 ± 0.06 157.4 ± 69.2 22.8 ± 3.9 67/72 (93.1%) 3.2 ± 1.2 14/72 (19.4%) 111 (59.7%) 104 (93.4%) 30.7 ± 9.5 35.0 ± 7.6 0.09 ± 0.27 192.3 ± 107.1 24.4 ± 5.7 93/104 (89.4%) 3.3 ± 1.2 16/104 (15.4%) 0.101 0.450 0.386 0.001 ,0.001 ,0.001 0.41 0.704 0.78 Bolded P value represents significant statistical difference between the 2 groups. logMAR, logarithm of the minimum angle of resolution. Patients in Group 1 and Group 2 were followed for an average number of 33.6 ± 26.4 and 93.1 ± 93.5 weeks, respectively. Fewer number of patients were on medical treatment at the final follow-up in Group 1 (9/75 [12.0%] vs 31/111 [27.9%]; P = 0.004). A lower proportion of patients experienced pulsatile tinnitus, TVOs, and diplopia, but there was no difference in reported headache at the final follow-up (Fig. 1). At the final follow-up, there was no significant difference in the OCT-RNFL thickness (123.2 ± 37.2 vs 120.2 ± 53.3 mm; P 0.58), and 68 of 75 patients (91.0%) in Group 1 and 100 of 111 (90.0%) had an OCT-RNFL thickness that was reduced at the final follow-up compared with the initial visit. Group-1 patients continued to have better logMAR visual acuity (0.03 ± 0.07 vs 0.08 ± 0.21; P 0.002) and Humphrey mean deviation (22.2 ± 2.9 vs 24.3 ± 6.7 dB; P , 0.001) at the final follow-up. As patients are not routinely discharged unless there is a special circumstance, follow-up was ongoing for 63 of 75 patients (84.0%) in Group 1 and 90 of 111 patients (81.0%) in Group 2. In Group 1, 8 were lost to follow-up and 4 were discharged to another eye care provider, and in Group 2, 10 were lost to follow-up and 11 were discharged to another eye care provider. CONCLUSIONS In our large cohort composed of IIH patients, incidentally discovered IIH represented just less than half (40.3%) of all IIH patients. Incidentally discovered IIH occurred in patients of a similar gender, age, or BMI as compared with patients seeking care due to symptoms. As expected, patients with incidentally discovered disease had lesser prevalence of headache, TVOs, diplopia, and pulsatile tinnitus. However, more than half of patients with incidentally discovered IIH had symptoms consistent with intracranial hypertension, including headache, which was present in more than 60.0% of patients and pulsatile tinnitus in 35.0%. Either these symptoms were mild and Vosoughi et al: J Neuro-Ophthalmol 2022; 42: 187-191 did not prompt these patients to seek medical attention or they were unrelated to IIH because primary headache disorders are common in young obese women (9). The relatively large number of patients with incidentally discovered papilledema illustrates the importance of careful examination of the optic nerve even in the absence of symptoms. Patients seeking care due to symptoms of IIH also had higher RNFL thickness, worse visual function, a higher LP opening pressure, and worse final visual outcome. However, there was no difference in the presence or severity of an empty sella, supporting the notion that the MRI should not be relied on to determine disease presence or severity. The characteristics and natural history of incidentally discovered or asymptomatic patients with IIH has not been extensively studied in adults. Previous cases have been described in the literature, where asymptomatic or incidentally discovered cases accounted for anywhere between 3.7% and 48.1% of cases (3,10–21). In the landmark IIH Treatment Trial, the proportion of asymptomatic cases was noted to be around 6% (3). However, the proportion of incidentally discovered cases was reported to be as high as 48.1% in a study by Blanch et al (12) in UK patients, which is similar to our study (40.3%). Interestingly, the proportion of incidentally discovered disease was lower in a US population (30.0%), which may be due to differences in access to primary eye care because the national population density of optometrists was found to be higher in the United Kingdom (21.37/100,000 population) and Canada (16.48/100,000 population) compared with United States (12.6/100,000 population) (22). Other studies have found that IIH patients with late-onset disease (older than 44 years) (10), asymmetric papilledema (11), and men with IIH (13) were more likely to be asymptomatic on presentation. Previous studies have also found that asymptomatic IIH accounted for anywhere from 3.0% (23), 22.6% (5), 31.1% (6), 33.3% (24), and 36.4% (25) of consecutive IIH patients younger than 18 years. This asymptomatic state was found to be associated with younger age and was less frequently associated with obesity (6). These 189 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution FIG. 1. Symptoms at presentation and final follow-up in patients with incidentally discovered IIH (Group 1) vs patients seeking care for symptoms of IIH (Group 2). P value represents comparison between the groups; ns, not significant (P . 0.05); *P # 0.05; **P # 0.01; ***P # 0.001. patients were also found to have milder optic disc edema, less frequent use of acetazolamide, and a lower incidence of posterior globe flattening (5). Visual loss is the major consequence of IIH, manifesting as deterioration in visual acuity, visual field, or both (26). Previous studies have found that the severity of papilledema and visual field impairment were significant predictors of final visual outcomes (3,27). Our study provides another useful way to stratify risk of visual loss in IIH patients: the way they entered the medical system. Three-quarters of patients with incidentally discovered disease were successfully managed without any medical or surgical treatment and only counselling on the importance of weight loss. More than half of patients who were started on medical treatment had it discontinued at the final follow-up. Moreover, most patients with incidentally discovered disease had LP deferred without any change to the diagnosis and visual outcome. This indicates that these patients require fewer health care resources and have a more benign course to their disease, consistent with their less symptomatic presentation. It is possible that many asymptomatic or paucisymptomatic IIH patients never receive a diagnosis. Interestingly, the radiological findings of an empty or partially empty sella was unable to differentiate between the group with incidentally discovered disease and those with a symptomatic presentation. We did not examine features other than an empty or partially empty sella because imaging findings generally appear to be more of diagnostic, rather than prognostic value. Previous studies show no correlation between features on neuroimaging and visual outcome as measured by mean deviation and visual acuity (28–32). Incidentally discovered patients were followed for a shorter period compared with patients who sought care for their symptoms. This was 190 explained by many patients’ initial presentation closer to the final follow-up as 1 neuro-ophthalmology practice (J.A.M.) was within 2 years of the final follow-up time. It is possible that this shorter time to follow-up in Group-1 patients may not capture any potential relapses over time that can occur in IIH patients. However, the large proportion of patients that had an improved OCT-RNFL thickness suggests that almost all patients had improvement. The strength of our study includes the relatively large sample size of consecutive IIH patients that were evaluated in a systematic fashion. This is also the largest proportion of patients with incidentally discovered disease analyzed in the literature. As many patients did not undergo an LP, they did not strictly meet the modified Dandy criteria. However, we were confident that these patients did not have pseudopapilledema because they were all evaluated with ancillary testing to rule out common causes of pseudopapilledema such as optic disc drusen. Moreover, most patients had at least a partially empty sella, and there was a large difference between the initial and final OCT RNFL thickness, which has been shown to be a strong differentiator between true and pseudopapilledema (33). Relying on the LP opening pressure to differentiate true from pseudopapilledema has also been shown to lead to significant diagnostic errors and overdiagnosis of IIH (34). Furthermore, none of these patients were found to have other secondary causes of intracranial hypertension, such as meningeal or neoplastic processes, at the follow-up and had no symptoms concerning for these diagnoses. Our previous study that included the same cohort also confirmed the absence of secondary causes of intracranial hypertension during a 63.3 weeks of follow-up period (35). Our results may also not be generalizable worldwide as access to optometry in Ontario, Canada may have influenced the discovery of papilledema and proportion of patients that presented in this manner. Our data support the notion that optometrists and ophthalmologists play an important role in discovering changes in the optic nerve. In conclusion, incidentally discovered IIH represented a large proportion of our IIH cohort. Despite not seeking medical care due to symptoms, more than half of patients reported a history of headache and about one-third had pulsatile tinnitus. Patients seeking care due to symptoms of IIH had higher OCT RNFL thickness, worse visual function, a higher LP opening pressure, and worse final visual outcome. However, there was no difference in the presence or severity of an empty sella. As a minority of incidentally discovered patients required treatment and the prognosis was favorable, differentiating patients based on how they enter the medical system is a valuable way to risk stratify IIH patients. STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: E. A. Margolin and J. A. Micieli; b. Acquisition of data: A. R. Vosoughi and J. A. Micieli; c. Vosoughi et al: J Neuro-Ophthalmol 2022; 42: 187-191 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution Analysis and interpretation of data: A. R. Vosoughi and J. A. Micieli. Category 2: a. Drafting the manuscript: A. R. Vosoughi, J. A. Micieli, and E. A. Margolin; b. Revising it for intellectual content: A. R. Vosoughi, J. A. Micieli, and E. A. Margolin. Category 3: a. Final approval of the completed manuscript: A. R. Vosoughi, J. A. Micieli, and E. A. Margolin. REFERENCES 1. Thurtell MJ. Idiopathic intracranial hypertension. 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