This study exhibited that the majority of IIH occurs mainly in obese female patients (BMI > 30 kg/m2) in childbearing period as mentioned in previous researches [3, 26] that may be attributed to hormonal dysregulation and changes in metabolic neuroendocrine axis in this age [27, 28].
In this study, headache of increased ICP was the core symptom presents in all patients and was the leading cause for asking medical advice as reported in other many studies; however, headache characters were nonspecific in the current study [5, 29]. As regards headache type, continuous headache was the main presenting complaint followed by chronic then episodic type, and this was consistent with Yri and Jensen [30] and inconsistent with Skau and colleagues; they reported that episodic headache was the main presentation followed by continuous type [31]. The main site of headache in the current study was bi-temporal, global, and then unilateral which was concordant with Elbanhawy and colleagues [9]. Bitemporal location, compressing, throbbing, and then dull aching headache were the main characters in this study, but Skau and colleagues found that there is no characteristic quality as regards headache in their study [31].
Severe headache which was associated with nausea and or vomiting with unilateral or bilateral pulsatile tinnitus was presented in the majority of patients. This manifestation coincides with other previous studies [32, 33]. The etiology of pulsatile tinnitus is not completely elucidated, but it is supposed that stenosis in the transverse sinus, which were commonly observed in patients of this study, may produce audible turbulences in blood flow [5, 34].
As regards visual abnormalities in the current study, blurred vision was the main visual complaint; photophobia is where the patient cannot tolerate the light; transient visual obscurations were common and described by the patients of this study as blacking out of vision lasting for seconds and were associated with pasture changes. Bilateral or unilateral sixth palsy due to raised ICP was presented in about one fifth of our patients and was associated with horizontal diplopia. This abnormality was concordant with Mollan and colleagues’ study [35], while Quattrone and colleagues found sixth nerve palsy occurred in about one fourth of cases. Sixth nerve palsy is explained by its longest intracranial course which makes it more susceptible for stretching and also more liable to the mechanical effects as the results of displacement of brain stem backward due to increased ICP [36, 37].
Papilledema was a cornerstone in patients of this study which was detected by fundus examination as in agreement with previous studies [28, 38]; all patients of this study suffered from papilledema; bilateral symmetrical in the majority of patients except 8 patients showed asymmetrical grades between the right and left eye not more than one grade difference; the severity ranged from grade I to grade IV; the majority of patients presented with grade III and then grade II, and this was concordant with the study of Sultan and colleagues [3] who reported the effect of elevated ICP on optic nerve.
The role of MRI and MRV imaging in IIH is to exclude any other causes of increased ICP and search for characteristic imaging signs that can be used for diagnosis of IIH such as empty sella, optic nerve sheath distention, flattened posterior globe, optic nerve tortuosity, and transverse sinus thrombosis [39].
The decrease of the pituitary gland mid-sagittal height was the oldest and the commonest used MR imaging sign for prediction of idiopathic increase intracranial tension [40]. Decrease pituitary gland height in IIH may be caused by arachnocele herniation through the diaphragma sellae [40]. Decrease in pituitary gland height may occur in normal individuals and in various chronic causes of intracranial hypertension like intracranial neoplasm or cerebral venous sinus thrombosis [20].
Many studies concluded that the sensitivity of empty sella in IIH was relatively high which ranged from 65 to 80%, and these were matched with the current study where the sensitivity of decrease the pituitary gland height for diagnosis of IIH was 85.2%. In this study, the specificity of decreased pituitary gland height for diagnosis of IIH was 91.2%, and this was in agreement with many studies who reported that the specificity of empty sella for diagnosis of idiopathic increase intracranial tension ranged from 70 to 100% [10, 20, 41, 42].
Intra-orbital MR imaging signs detected in IIH include optic nerve sheath distention, flattened posterior globe, and optic nerve tortuosity. These signs are proved to be due to increased intracranial CSF pressure in IIH that is conducted to the intra-orbital part of optic nerve leading to increase CSF pressure in the subarachnoid space around the optic nerve [20].
In this study, the sensitivity and specificity of optic nerve sheath distention for diagnosis of IIH were 85.2% and 91.1 respectively, and these were higher than the results of many researches who concluded that optic nerve sheath distention was less sensitive (51%) and only moderately specific (83%) for diagnosis of IIH [2, 20].
In this study, the sensitivity and specificity of flattened posterior globe for diagnosis of IIH was 76.4% and 100% respectively, and these were in agreement with many studies who concluded that the sensitivity of flattened posterior globe for diagnosis of IIH varies between 43 and 85%, and with 98% specificity [10, 20, 41, 42].
In this study, the sensitivity and specificity of optic nerve tortuosity for diagnosis of IIH were 26.5 % and 100% respectively, and these were in agreement with many studies which concluded that the optic nerve tortuosity has low sensitivity (43%) and high specificity (90%) in diagnosis of IIH [10, 20, 41, 42].
In the current study, the presence of 3 or more MRI findings increases the sensitivity and specificity of MRI in diagnosis of idiopathic increase intracranial tension to 85.2 and 100% respectively with an accuracy of 92.2%; this was in agreement with Mallery and his colleagues’ study; they concluded that the combination of any three or more MRI findings is highly specific for diagnosis of idiopathic increase intracranial tension [43].
The main indication of MRV in patients of IIH is exclusion of cerebral venous sinus thrombosis. In these patients, MRV allows the evaluation of transverse/sigmoid sinus patency [44].
In this study according to the side of transverse sinus stenosis, the sensitivity and specificity of bilateral transverse sinus stenosis were higher (65.2% and 100% respectively) in the diagnosis of IIH than the sensitivity and specificity of unilateral transverse sinus stenosis (57.9 and 88.2 respectively) with total sensitivity and specificity of 76.5 and 88.2% respectively. This was in agreement with Farb and colleagues, Riggeal, and his colleagues’ studies; they concluded that the sensitivity and specificity of bilateral transverse sinus stenosis in diagnosis of idiopathic increase intracranial tension using MRV were high (93% and 100% of both studies respectively) [39, 44]. This study was also matched with the study of Mallery and his colleagues which concluded that the sensitivity of transverse sinus stenosis either bilateral or unilateral in diagnosis of IIH was 78% [10]. The study of Samanc and colleagues reported that bilateral transverse venous sinus stenosis is a common finding in intracranial hypertension patients without IIH and also may occur in normal individuals [20].
The study of Morino and his colleagues reported that transverse sinus stenosis either unilateral or bilateral is commonly seen in patients with idiopathic increase intracranial tension. It was still unknown if transverse sinus stenosis occurred as a cause or as a result of increase intracranial CSF pressure, because increased intracranial pressure exerts a compression on the transverse sinus and subsequent venous outflow obstruction. On the other hand, this obstruction caused decreases of the CSF absorption. Also, it was observed that bilateral transverse sinus stenosis stenting can decrease the elevated intracranial pressure. Also, normalization of intracranial pressure can resolve transverse sinus stenosis [40].
In the current study, the sensitivity and specificity of using 4 or less combined conduit score in the diagnosis of idiopathic increase intracranial tension were 85.3% and 94.1% respectively; this was not matched with the study of Ramesh and his colleagues as they concluded that the sensitivity (90%) of combined conduit score in the diagnosis of IIH was higher than its specificity (86.6%). This may be due to the selection of higher CCS cutoff value in the study of Ramesh and his colleagues; so many borderline false positive and false negative values were included in their results [45].
In conclusion, the combination of any three or more MRI findings as regards decreased pituitary gland height, optic nerve sheath distention, flattened posterior globe, and optic nerve tortuosity greatly increased the specificity and sensitivity for diagnosis of idiopathic increase intracranial tension. The presence of MRV findings as regards bilateral transverse sinus stenosis and less than or equal 4 combined conduit score also increased the specificity and sensitivity for the diagnosis of idiopathic increase intracranial tension.
Cognitive affection in patients with IIH has been reported in previous studies [25]. In all studies, apart from the case report by Kaplan and colleagues, 5 testing revealed significant cognitive impairment in patients with IIH especially in memory and verbal tests [46]. CI in patients with IIH occurs as a result of brain dysfunction which could be related to axonal flow as in optic nerve hydrops or impaired function of grey and or white matter of the brain as a result of mechanical compression [47].
In the current study, cognitive impairment (MoCA < 26) was observed in about 44% in the patients and showed to be highly statistically significantly lowered when compared with patients in the control group (P < 0.001) and also when compared with patients and control total MoCA score and percentage (P = 0.005); comparing different cognitive domains, all domains are affected when comparing patients with control subjects especially memory and abstraction which showed to be highly statistically significantly lower than the control (P < 0.001 and P = 0.007 respectively); this is consistent with Yri and colleagues; they found that IIH patients performed significantly worse cognitive function than controls in four of six cognitive domains. Deficits were prominent in reaction time and processing speed, significant impairment in working memory, and significant lower score in cognitive flexibility subset measuring [25].
In this study, comparing patients with cognitive impairment with patients with normal cognitive function, we found that low education level showed statistically significant lower cognitive function when compared with high education level (P = 0.042) which may be attributed to social state; this is consistent with Yri and his colleagues; they found that IIH is a state of socioeconomic consequences especially for young patients of working age [25]. Mollan and his colleagues found that patients living in a low socioeconomic state have a less resources to perform higher education with subsequently increased prevalence of obesity and therefore have increased incidence of IIH [48].
In this study, we found that diplopia had detrimental effect on cognition in which patients with diplopia showed statistically significant cognitive impairment when comparing patients with and without diplopia (P = 0.002); this was consistent with Shipster and his colleagues; they found that many factors have a potential effect, alone or in combination, to cause impairment in neurocognitive function in patients with ICP like diplopia and impaired hearing [49]. Our study showed that patients used contraception had statistically significant cognitive impairment when compared to non-cognitive impairment group (P = 0.004); the explanation is that the hormonal contraception increases the risk of obesity due to effect of progesterone which increases the appetite or facilitates anabolism while estrogen aggravates fat accumulation in adipose tissues and cells [50].
In current study, the cutoff opening pressure was 56 cm H2O in which patients with opening pressure ≥ 56 cm H2O showed statistically significant cognitive impairment when compared to non-cognitive impaired group (P = 0.002). This could be attributed to high pressure that causes mechanical compression with disturbed the function of grey and or white matter of the brain [47, 51]; reduction in cerebral blood flow that occurs in IIH may partly explain cognitive impairment in these patients.
In this study, the patients with increased BMI showed statistically significant cognitive impairment when compared with low BMI (P = 0.025). In the current study, patients with high-grade papilledema showed highly statistically significant cognitive impairment when compared with patients with low-grade papilledema on the right and left eye respectively (P = 0.003, P = 0.001).
We recognize limitations to this study. First, sub-analyses were limited due to small sample size; multivariable logistic regression was not run for the study. Second is the absent follow-up of the patients; lastly is the inability to assess the effect of different lines of treatment on cognition.