In our study, the mean age was 29.1 years, and females accounted for 90.6% of all patients, which was similar to many previous studies that reported a high incidence in females, such as Zhoua et al. [11], Saber et al. [12], and Agarwal et al. [13], in which females represented 90%, 86%, and 82% of the total study populations, respectively. IIH is common in overweight persons, and the mean body mass index of most studies was more than 25 kg/m2. In the current study, the mean body mass index was 33.2 kg/m2, and it was 35.4 kg/m2, 35 kg/m2, 34.8 kg/m2, and 27.1 kg/m2 in Patsalides et al. [14], Chagot et al. [15], Saber et al. [12], and Agarwal et al. [13], respectively.
The mean opening CSF pressure at the time of diagnosis varies; in the current study, it was 38.2 cmH2O, which was similar to the result reported in Patsalides et al. [14] study, which was 37 cmH2O. Chan [16] reported a higher value for the opening CSF pressure of 41.4 cmH2O; on the other hand, Smith and Friedman [17] and Chagot et al. [15] obtained lower values, namely, 34.3 cmH2O and 28.5 cmH2O, respectively.
Clinical manifestations varied; in the current study, headache and visual complaints were the most common, followed by nausea, while diplopia and tinnitus were the least common manifesting complaints. In this study, headache was present in all patients; it was migraine-like in 19/32 (59%), was tension-like in 9/32 (28%), and could not be classified in 4/32 (13%) patients. The headache was frontal, fronto-orbital, occipital, and parietal in 11/32 (34%), 8/32 (25%), 7/32 (22%), and 6/32 (19%) patients, respectively.
Headache was the most common symptom in Agarwal et al. [13], Smith and Friedman [17], Watane and Patel [7], and Chagot et al. [15], as it was found in 89.3%, 84%, 82.2%, and 82% of patients, respectively. The headache characteristics in this study were similar to those of patients in Friedman et al. [18] because the most common headache phenotypes were migraine, accounting for 52%; followed by tension-like, accounting for 22%; and unclassified, accounting for 7% of their patients.
Friedman et al. [18] supposed that elevated CSF pressure might lead to persistent and chronic trigeminal activation and irritation. This trigeminal dysfunction could result in chronic dysregulation of the normal mechanisms that suppress inappropriate trigeminal nociceptive activity, leading to migraine-like headache. Friedman et al. [18] connected the intermittent course of the headache to the natural fluctuations in CSF pressure throughout the day. Eren et al. [3] reported that the differences in ventricular compliance and the duration of increased intracranial pressure could explain the clinical differences between IIH patients with or without headaches; they performed a retrospective study of 152 children with IIH, and 14.5% of the patients had no headache.
Transient visual obscuration was noticed at the time of diagnosis of IIH in 25/32 (78%) of patients with preserved vision, while it was identified in 70%, 69.1%, and 68% of the patients in Markey et al. [19], Wall [20], and Smith and Friedman [17], respectively.
Tinnitus was found in 40.6% (13/32) of the patients in this study, while it was found in 56%, 52.4%, and 48.9% of the patients in Markey et al. [19], Agarwal et al. [13], and Saber et al. [12], respectively. Diplopia was present in 15.6% (5/32) of patients at the time of presentation in this study, which is more or less similar to the 17% reported by Agarwal et al. [13].
Visual complaints in our study contributed to decreased visual acuity, transient visual obscuration, papilledema, and visual field defects. All patients complained of decreased visual acuity, but we did not have a previous baseline for visual acuity. Two (6.3%) patients had visual acuity less than 1/60, one (3.1%) patient had bilateral ability to count fingers, and the other had no light perception in either eye. Watane and Patel [7] and Friedman et al. [18] reported diminution of vision in 45.57% and 34% of their patients, respectively. Agarwal et al. [13] had a high proportion of patients with poor visual acuity (less than 6/18) and diminution of vision at presentation (36% and 62%, respectively), while the percent was 72.7% in Saber et al. [12].
In the current study, fundoscopic examination at the time of IIH diagnosis revealed bilateral post-papilledema optic atrophy in one (3.1%) patient and bilateral papilledema in all other patients. The grades were as follows: 15.6%, 43.7%, 31.3%, and 6.3% had grades 1, 2, 3, and 4, respectively.
Regarding visual field defects in the current study detected with standard automated perimetry, there were defects in all our patients. The average mean PMD for 30 patients was − 18 dB ± 9.97 in the right eye and − 19.47 dB ± 5.43 in the left eye. We could not evaluate the visual field in two patients due to the marked diminution of vision. Chagot et al. [15] and Zhoua et al. [11] reported visual field defects in 87% and 86.7% of their patients, respectively. In Smith and Friedman [17], the average PMD at baseline was − 23.5 dB, while in Pircher et al. [21], the average visual field mean deviation was 6.6 ± 8.5 dB on the right side and 6.9 ± 7.9 dB on the left side. In the current study, an enlarged blind spot was the most common defect observed at baseline followed by generalized constriction of the visual field, and the defect was more or less symmetrical in both eyes in most cases. In Markey et al. [19], an enlarged blind spot, loss of the nasal visual field, and generalized visual field constriction patterns were the most common defects and were found in 80%, 72%, and 54% of the patients, respectively, while glaucoma-like arcuate field loss was the most common abnormality, followed by an isolated enlarged blind spot in Smith and Friedman [17].
In the current study, we achieved a reduction of 22.4 cmH2O in the CSF opening pressure, with a post-treatment mean value of 15.8 cmH2O for non-surgically treated patients, which is similar to that reported in Patsalides et al. [14], in which they achieved a reduction of 22.9 cmH2O in the CSF opening pressure after 3 months of treatment. The mean reduction in the CSF opening pressure is most likely related to the average pretreatment intracranial pressure, the tolerance of acetazolamide use, and other risk factors contributing to IIH development, such as high body mass index.
In our study, the headache completely disappeared in 100% of patients who received theco-peritoneal shunts and in 20/24 (83%) patients who were treated by medical treatment only. Julayanont et al. [22] reported headache improvement in 92% and 83% of patients in two different previous studies following theco-peritoneal shunt insertion.
In our study, visual acuity did not improve in the patient who had no light perception pre-operatively, but the other patient with the ability to count fingers had visual acuity of 1/60 in the right eye, while the left eye did not improve. Other patients had a subjective sensation of improved visual acuity following normalization of increased intracranial pressure. Kalyvas et al. [23] achieved visual improvement and papilledema resolution for all patients after normalization of intracranial pressure, while the percent of patients who achieved visual improvement was only 70.3% and 55% in Scherman et al. [6] and Saber et al. [12], respectively. Chagot et al. [15] were characterized by a high rate of poor visual outcome at 6 months of follow-up, but they attributed that to a high percentage of patients with observed weight gain at 6 months. Agarwal et al. [13] concluded that reduced vision at baseline is a predictor of a poor visual outcome, while patients with preserved vision usually have a better prognosis.
We reported papilledema resolution in 100% of patients with pre-management papilledema. Saber et al. [12] and Scherman et al. [6] reported papilledema improvement in 85.8% and 71% of the patients, respectively, following IIH management. Agarwal et al. [13] reported that patients who had papilledema at the time of diagnosis usually had a good prognosis. Markey et al. [19] attributed the cause of papilledema to the transmission of elevated intracranial pressure via the CSF to the retrobulbar optic nerve sheath.
The visual field outcome is expressed by the change in the average perimetric mean deviation from baseline. All our patients had improved visual field on follow-up perimetry performed at 1.5 months following the complete resolution of papilledema, with the exception of the two patients with severely reduced visual acuity; the mean PMD for the right eye was − 16.50 dB with a mean improvement in PMD of 1.5 dB, while the mean PMD for the left eye was − 16.10 dB with a mean improvement in PMD of 3.37. Wall [21] reported complete or nearly complete resolution of visual field deficits in 92% (11/12) of their patients, with a mean PMD improvement of 6.35 dB in the patients who received a theco-peritoneal shunt. Agarwal et al. [13] reported that patients with a poor visual acuity outcome also had a poor visual field outcome, as he had 48 patients with good visual acuity outcome and 10 (17.2%) patients with poor visual outcome, and 32 patients with a good visual acuity outcome had a good visual field outcome, and 9 patients with a poor visual acuity outcome had a poor visual field outcome.
