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Show Journal of'A] euro- Ophthalmology 21( 1): 12- 14, 2001. © 2001 Lippincott Williams & Wilkins, Inc., Philadelphia Epidemiology of Idiopathic Intracranial Hypertension in Israel Anat Kesler, MD, and Natan Gadoth, MD Objectives: To determine the incidence, demographic, and clinical features of Pseudo Tumor Cerebri ( PTC)/ Idiopathic Intracranial Hypertension ( IIH) in Israel. Materials and Methods: The chairpersons of all neurology and ophthalmology departments in Israel were asked to complete questionnaires regarding patients diagnosed with PTC/ IIH from 1998 through 1999. Each questionnaire contained details regarding patient's age, sex, country of birth, age at diagnosis, weight, height, presence of obesity, and the results of lumbar puncture, brain computed tomography, magnetic resonance imaging, and/ or magnetic resonance venography. Results: Ninety- one patients with PTC/ IIH were diagnosed during the years 1998 to 1999. Eighty- five ( 93.4%) patients were females and six ( 6.6%) patients were males. The calculated incidence of PTC/ IIH in the Israeli general population was 0.57 to 0.94 per 100,000 persons, with incidences of 1.82 per 100,000 for women and 0.034 per 100,000 for men. The incidence for women during the childbirth years was 4.02 per 100,000. The female to male ratio was higher than previously reported for Western countries. Conclusions: Although the population of Israel is a mixture of people originating from Eastern and Western countries, the incidence of PTC/ IIH was found to be similar to that of Western countries. This finding is an additional support to the notion that PTC/ IIH is more common in obese populations. Key Words: Epidemiology- PTC- IIH- Obesity. Pseudotumor cerebri ( PTC) is the term commonly used for the association of increased intracranial pressure without clinical, laboratory, or radiologic evidence of an intracranial space- occupying lesion ( 1- 3). However, idiopathic intracranial hypertension ( IIH) may be a more suitable term ( 4). Thus, IIH will be used throughout this article. To establish a diagnosis of IIH, the following criteria must be fulfilled ( Table 1): 1) elevation of intracranial pressure (> 200 mm H20), 2) normal cerebrospinal fluid ( CSF) composition, 3) normal neuroimaging ( except for empty sella), Manuscript received July 10, 2000; accepted October 27, 2000. From the Department of Neurology, Meir General Hospital, Kfar Saba, and the Sackler Faculty of Medicine, Tel- Aviv University, Tel Aviv, Israel. Address correspondence and reprint requests to A. Kesler, MD, Dept. Neurology, Meir General Hospital, Kfar- Saba 44281, Israel; e- mail: kesler@ netvision. net. il. 4) normal neurologic examination, except for papilledema and abducens nerve paresis. The typical patient with IIH is a young and obese female ( 1). Although IIH is usually a self- limiting condition, it may become chronic in some patients ( 5). The hospital incidence reported in several large series implies that IIH is a rare condition ( 2,5- 9). In recent surveys, an annual incidence rate of 1 to 2 per 100,000 persons was found in the general population ( 1,6,7). The aim of this study was to determine the population- based incidence and provide the demographic and clinical features of IIH in Israel. METHODS The chairmen of all neurology and ophthalmology departments in Israel were personally asked to provide comprehensive details on patients with new onsets of PTC/ IIH diagnosed in their institution during the years 1998 to 1999. They were required to complete a questionnaire containing the patient's age, sex, country of birth, age at diagnosis, weight, height, presence of obesity, lumbar puncture results, and the results of CT, MRI and/ or MRV for each patient with PTC/ IIH. A similar request was made through the Israel Medical Association Journal, which is distributed freely to all its members. Relevant demographic data were obtained from the Israeli Central Bureau of Statistics. RESULTS Of 22 hospitals providing tertiary medical care to the Israeli general population, seven small regional hospitals routinely refer patients with IIH to a major hospital. The TABLE 1. Modified Dandy's criteria for diagnosing idiopathic intracranial hypertension • Symptoms and signs of increased intracranial pressure in an awake and alert patient • No abnormal neurologic signs other than abducens nerve paresis • Normal neuroimaging except for empty sella • CSF opening pressure > 200 mm H20 in nonobese and > 250 mm H20 in obese patients. Normal composition of CSF • No other known causes of intracranial hypertension CSF, cerebrospinal fluid. Data from Radhakrishnan et al. ( 1) and Ahlskog and O'Neil ( 3). 12 EPIDEMIOLOGY OF PSEUDOTUMOR CEREBRI 13 TABLE 2. Clinical and demographic data on 91 patients with idiopathic intracranial hypertension All patients Females ( n = 85) Males ( n = 6) ( n = 91) ( 93.41%) ( 6.59%) Age at diagnosis, y 32.34 ± 11.01 31.62 ± 10.29 42.33 ± 16.48 CSF opening pressure ( mm H20) 340 ± 93.99 343 ± 95.35 282 ± 22.17 CSF, cerebrospinal fluid. remaining 15 hospitals have an active neurologic department and ophthalmology or neuro- ophthalmology consultation services. We obtained complete data from 13 hospitals. Data were either unavailable or incomplete in two hospitals. Complete questionnaires for 91 patients with IIH who were diagnosed during 1998 to 1999 were received. There were no duplicate cases, as judged by names and identity card numbers. Sinus vein thrombosis was excluded by contrast-enhanced computed tomography ( CT) in all 91 patients. Additional neuroimaging was performed: magnetic resonance imaging ( MRI) in 36 patients, magnetic resonance venography ( MRV) in eight patients, and computed tomography venography ( CTV) in three patients. Eighty-five ( 93.4%) patients were females and six patients ( 6.6%) were males. The females were younger than the males. Data regarding the presence of obesity were available in 63 patients ( 57 females and six males). There were 36 obese patients, 35 were females. The presence of obesity was determined in 26 patients, according to the examiner's clinical impression, and in ten patients when body mass index ( BMI) was greater than 30 kg/ m2. The presence of obesity could not be associated with age of onset or opening CSF pressure. The males were older, but this observation did not reach statistical significance ( 42.33 and 31.61 years, respectively; p = 0.174). The Israeli population in the 1998 census was 5,970,000. Thus, the calculated incidence of IIH in the Israeli general population based on the current study was 0.94 per 100,000 persons, with the incidence for women 1.82 per 100,000 and men 0.034 per 100,000. The incidence for women during childbirth years ( 18^ 45 years) was 4.02 per 100,000. The population in the 1999 census was 6,100,000 persons, and the calculated incidence was 0.57 per 100,000. The country of birth and ethnic origin was documented in 65 patients; 53 were born in Israel, five in the former Soviet Union, four in Morocco, two in Iraq, and one in the United States. The mean CSF opening pressure in females was higher than in males. Statistical TABLE 3. Body dimensions in 63 patients with idiopathic intracranial hypertension Total Females Males Obese ( 36) 35 1 57.2% 97.2% 2.8% Nonobese ( 27) 22 5 42.8% 81.5% 18.5% significance, however, could not be calculated because of small sample size. The demographic and clinical data of the patients are shown in Tables 2 through 4. DISCUSSION In this countrywide study, we obtained clinical and demographic information on patients with IIH diagnosed in the hospital setting in most neurology departments in Israel. Patients with IIH are customarily hospitalized in neurologic wards and seen concomitantly by a neurologist and an ophthalmologist or neuro- ophthalmologist. Moreover, lumbar punctures are performed only in neurologic wards. Thus, we believe that this group of patients represents IIH incidence in Israel during the years 1998 to 1999. The systematic and annual census performed yearly by the Israeli Bureau of Statistics enabled us to confidently calculate the yearly incidence rates of IIH for the period of this survey. The incidence of IIH varies throughout the world. It is almost unknown in countries in which the incidence of obesity, a significant factor in the idiopathic form of this condition, is low, and is common in countries with an increased incidence of obesity. We found an annual incidence of 0.57 to 0.9 per 100,000 persons in the general population and 4.02 per 100,000 in females aged 15 to 45 years. A similar incidence was found by Durcan et al. ( 6) in Iowa and Louisiana ( 0.9 per 100,000 persons). Radhakrishnan ( 1) reported an incidence of 1 per 100,000 persons in Rochester, Minnesota, whereas in Benghazi, Libya, it was 2.2 per 100,000 persons in the general population and 4.3 per 100,000 in women ( 10,11). Data on the incidence of IIH in several published studies are shown in Table 5. The incidence of IIH in countries such as Libya and Saudi Arabia is likely to be higher than in Western countries because of the higher prevalence of obesity among females of reproductive age ( 4,10). However, the geographic variation in the incidence of IIH requires additional epidemiologic studies. The female preponderance and relatively high frequency of obesity found in many previous surveys ( 2,6, 8,9) were also found in this study. The female to male TABLE 4. Distribution of patients according to ethnic origin and place of birth ( n = 65) Place of birth Israel Other 53( 81.54%) 12( 18.46%) Ethnic origin Jewish Arab 48( 73.85%) 17( 26.15%) J Neuro- Ophthalmol, Vol. 21, No. 1, 2001 14 A. KESLER AND N. GADOTH TABLE 5. Incidence of idiopathic intracranial hypertension/ pseudotumor cerebri Study period, y Population No. of patients Female/ male ratio Obesity, % Incidence Incidence female Incidence females 15- 45 y Minnesota 15 70,000 9 8 70 0.9 1.6 3.3 Iowa 1 2,914,000 27 8 67 0.9 - 3.5 Louisiana 1 4,481,000 48 4.3 69 1.07 - 3.5 Benghazi, Libya 2 519,000 18 1 74 1.7 3.6 10.3 Israel 2 6,000,000 91 14 57 0.94 1.82 4.02 ratio was 14 to 1. This finding is higher than in Iowa ( 9) and in Louisiana ( 3,6). This ratio was the lowest ( 1 to 8) in the Johnson study ( 11). In a few studies, only females were reported ( 10,12). Obesity is a significant risk factor for IIH. In this study, obesity was present in 97.2% of the females and in only 2.8% of the males. Although these values concern only 63 of the 91 patients whose body dimensions were available or who were considered markedly overweight according to personal subjective impression, they probably represent the whole study population. In the report by Johnston and Paterson ( 11), only 34% of patients were considered obese. Radhakrishnan ( 10), using a definition of obesity as body weight greater than 20% of optimal, found that 74% of Libyan patients were obese compared to 69% in Louisiana ( 6). In Israel, a country with a large number of immigrants, most patients with IIH were native Israelis. This might be related to the fact that the peak of immigration to Israel occurred between 1950 and 1960, and our patients are mostly the offspring of those early immigrants. The higher CSF opening pressure in females may be secondary to obesity. Indeed, Mosek ( 13) recently showed that opening CSF pressure is elevated in obese subjects. On the other hand, Corbett and Mehta ( 14) found that there was no significant statistical different between mean CSF pressures in obese and nonobese healthy subjects; however, those results were obtained with a small sample size. The current study suffers from several weaknesses: 1) It is a retrospective study, 2) Obesity was determined according to BMI in 27.7% of the obese patients only, whereas the other 72.73% were considered obese according to personal impression, 3) Other causes of IIH such as hypervitaminosis A, steroid withdrawal, and the use of certain drugs were not included in the questionnaire. Because these conditions are not common, the results were probably not significantly affected. In spite of its weaknesses, this study implies that IIH in Israel is as common as in Western countries. This finding probably reflects the increasing incidence of obesity in Western communities. Acknowledgments: The authors thank O. Abramsky, MD, PhD; Y. Almog, MD; I. Bloch, MD; R. Carasso, MD; S. Dotan, MD; Y. Goldhammer, MD; Y. Harishanu, MD; S. Honigmann, MD; E. Kahana, MD; A. D. Korczyn, MD, MSc; J. Mannelis, MD; M. J. Rabey, MD; E. Melamed, MD; B. Scharff, MD; M. Sadeh, MD; Y. Vardi, MD; and D. Yarnitzky, MD for providing data on their patients. REFERENCES 10 n 12 13 14 1. Radhakrishnan K, Ahlskog JE, Cross SH, et al. Idiopathic intracranial hypertension ( Pseudotumor cerebri). Descriptive epidemiology in Rochester, Minn. 1976 to 1990. Arch Neurol 1993; 50: 78- 80. 2. Weisberg LA. Benign intracranial hypertension. Medicine 1975; 54: 197- 207. 3. Ahlskog JE, O'Neil BP. Pseudotumor cerebri. Ann Intern Med 1982; 97: 249- 56. 4. Miller NR, Newman NJ. Chapter 10. In: Walsh and Hoyt's Clinical A'euro- ophthalmology. 5th ed. Baltimore: Williams & Wilkins, 1998; 523- 30. 5. Corbett JJ, Savino PJ, Thompson HS, et al. 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