Idiopathic intracranial hypertension – a wider spectrum than headaches and blurred vision

Abstract

Background

The purpose of this study was to analyse less known clinical scenarios associated with idiopathic intracranial hypertension.

Methods

The study involved analysis of magnetic resonance imaging signs of idiopathic intracranial hypertension in patients with spontaneous rhinoliquorrhoea (n = 7), in patients with temporal lobe epilepsy and surgically treated antero-inferior temporal lobe meningo-encephaloceles (n = 15), and in patients who developed clinical signs of idiopathic intracranial hypertension following the treatment of spontaneous intracranial hypotension (n = 7).

Results

Three of six patients with spontaneous rhinoliquorrhoea and six of 15 operated patients with temporal lobe epilepsy due to temporal lobe meningo-encephaloceles showed magnetic resonance imaging signs of idiopathic intracranial hypertension and had a body mass index >30 kg/m². Rebound high pressure headaches and sings of idiopathic intracranial hypertension occurred in seven of 44 surgically treated spontaneous intracranial hypotension patients.

Conclusions

Magnetic resonance imaging findings should guide the clinician to consider (idiopathic) intracranial hypertension when patients develop spontaneous rhinoliquorrhoea, temporal lobe epilepsy secondary to temporal lobe meningoencephaloceles or high pressure headaches in spontaneous intracranial hypotension. Whether idiopathic intracranial hypertension must be regarded as a differential diagnosis or as a cause, or whether there are common pathophysiological pathways that lead to signs of idiopathic intracranial hypertension in this wider spectrum of disease is the focus of further study.

Idiopathic intracranial hypertension (IIH) is a headache syndrome associated with elevated intracranial pressure in the absence of a space-occupying lesion and mostly occurs in obese women of childbearing age. Diagnostic criteria include a cerebrospinal fluid (CSF) pressure exceeding 250 mm and that (a) the headache has developed or significantly worsened in temporal relation to the IIH or has led to its discovery and/or (b) that the headache is accompanied by a pulsatile tinnitus and/or papilloedema. ¹ Magnetic resonance imaging (MRI) findings include empty sella, distention of the perioptic subarachnoid space, flattening of the posterior sclerae, protrusion of the optic nerve papillae into the vitreous body and transverse sinus stenosis.^1–5 Since headaches and/or visual symptoms are not always present, diagnosis of some entities associated with IIH might missed. Such entities are spontaneous rhinoliquorrhoea, antero-inferior temporal lobe meningo-encephaloceles and temporal lobe epilepsy (TLE), as well as rebound intracranial hypertension (RIH) following the treatment of spontaneous intracranial hypotension (SIH).^6–13 Here, we analysed clinical and imaging presentations of consecutive patients out of these entities that were treated at our institution. The aim of the study was to describe frequencies of IHH signs on MRI in this wider spectrum of disease and to identify possible common patterns.

Methods

We carried out retrospective analysis of the clinical characteristics and imaging work-up for: (a) patients with spontaneous rhinoliquorrhoea; (b) patients with TLE and operated antero-inferior temporal lobe meningo-encephaloceles; and (c) patients who developed clinical signs of IIH following the surgical treatment of SIH.

The search for (a) and (b) was confined to the years 2014–2020 and conducted in the Radiology Information System (RIS) and Picture Archieving Communication System (PACS) systems using the OPS codes 3-3130 and 2-340 and the terms ‘Zisternographie’ or ‘Enzephalozele’ or ‘Meningoenzephalozele’. The search for (c) was confined to the years 2018–2020, conducted in the RIS and PACS systems using the Operations and Procedure Code (OPS) codes 3-3130 and 2-340 and the term ‘Liquorunterdruck’.

Clinical presentations, diagnostic work-up and therapeutic interventions were taken from the patient’s charts.

MRI signs of IIH were assessed by two neuroradiologists (HU, IED), and different readings were solved in a consensus reading. The following signs were documented: prominent subarachnoid spaces around the optic nerves (see Tables: 1-3), vertical tortuosity of the optic nerves (2), enlarged arachnoid outpouchings with partially empty sella (3a), enlarged Meckel’s cave (3b), prominent arachnoid pits/aberrant arachnoid granulations/small meningoceles typically within the temporal bone and sphenoid wing (3c), enlarged CSF space around the oculomotor nerves in the lateral wall of the cavernous sinus (3d), bilateral venous sinus stenosis or unilateral stenosis and contralateral hypoplasia (4), acquired tonsillar ectopia (mimicking Chiari I malformation) (5).

All procedures in this study were in accordance with 1964 Declaration of Helsinki and its later amendments and proven by the local ethics committee (EK 406/17, 357/20). Informed consent was waived.

Results

Demographic data, imaging work-up and findings, and therapeutic outcomes are summarised in Tables 1–3.

Table 1.

Spontaneous rhinoliquorrhoea.

No.	Age, gender	BMI/kg/m²	MRI signs of IIH	CSF opening pressure/cm H2O	Diagnostic modality	Diagnosis
1	54, f	42	1, 3a, 3b, 3c, 3d, 4	–	CT and Magnetic Resonance (MR) cisternography with coronal and axial 3 mm T1-w fat sat sequences	Spontaneous rhinoliquorrhoea with CSF leak at left anterior cribriform plate without bony defect. Recurring leak 3 years later
2	83, f	38	3a, 3c	–	CT and MR cisternography with coronal and axial 3 mm T1-w fat sat sequences	Spontaneous rhinoliquorrhoea with anterior temporal encephalocele and bony defect extending into the lateral recess of sphenoid sinus. Persisting rhinoliquorrhoea at left cribriform plate
3	55, f	24	1, 3a, 4	33	CT and MRI cisternography with CSSPACE	Spontaneous rhinoliquorrhoea with CSF leak at left anterior cribriform plate without bony defect
4	60, f	32.3	1, 3a, 3b, 3c, 4, 5	–	CT and MRI cisternography with CSSPACE	Spontaneous rhinoliquorrhoea with CSF leak at left cribriform plate with bony defect
5	69, f	24.7	3c	–	CT and MRI cisternography with CSSPACE	Spontaneous rhinoliquorrhoea due to CSF leak at right cribriform plate
	69, f	24.7	3c	–	CT and MRI cisternography with CSSPACE	Recurring leak after surgical repair of a CSF-leak right cribriform plate
6	46, m	27.2	3b, 3c, 3d, 4	–	CT and MRI cisternography with CSSPACE	Spontaneous rhinoliquorrhoea due to encephalocele and CSF leak at infero-lateral recess of left sphenoid sinus

BMI: body mass index: CSF: cerebrospinal fluid; CSSPACE: Compressed Sensing Sampling Perfection with Application optimized Contrasts using different flip angle Evolution; CT: computed tomography; f: female; IIH: idiopathic intracranial hypertension; m: male; MRI: magnetic resonance imaging.

Table 2.

Temporal lobe epilepsy (TLE) and meningo-encephaloceles.

No.	Age, gender	BMI	MRI signs of IIH	Epilepsy syndrome	Diagnostic modality	Diagnosis	Therapy	Outcome/Engel, Wieser (follow-up time)
1	55, m	32.2	3a, 3b	Dyscognitive and bilateral tonic-clonic seizures since 6 years	MRI, CT skull base	SEEG-proven TLE due to left temporal lobe meningoencephaloceles, 2 left	Resection of temporal pole including the meningoencephalocele	1A, 1 (52 months)
2	21, m	24.7	no	Dyscognitive seizures since 3 years	MRI, CT skull base, fMRI, PET-CT, video-EEG-monitoring	TLE due to left temporal pole meningoencephaloceles, 2 left	Resection of the temporal pole including the two meningoencephaloceles	1A, 1 (48 months)
3	35, m	26.6	2, 3a	Dyscognitive seizures and bilateral tonic-clonic seizures since 10 years	MRI, CT skull base, PET-CT, EEG-monitoring	TLE due to left temporal pole meningoencephaloceles 2 left	Resection of the temporal pole including the encephalocele	3A, 2 (12 months)
4	32, f	24.7	1, 2, 3b	Dyscognitive seizures and bilateral tonic-clonic seizures since 10 years	MRI, CT skull base, fMRI, PET-CT, video-EEG-monitoring,	TLE due to left temporal pole meningoencephalocele 2 (1 left, 1 right)	Resection of the left temporal pole including the meningoencephalocele	1B, 2 (17 months)
5	28, m	30.1	no	Psychic auras, dyscognitive seizures, and rare bilateral tonic-clonic seizures since 11 years	MRI, CT skull base, fMRI, PET-CT, video-EEG-monitoring	SEEG-proven temporal lobe epilepsy due to left temporal pole meningoencephaloceles 3 (2 left, 1 right)	Resection of the left temporal pole including the meningoencephaloceles	1A, 1 (24 months)
6	47, f	21.3	1, 2, 3a, 3b, 3c, 3f, 4	Epigastric auras, dyscognitive seizures and bilateral tonic-clonic seizures since 15 years	MRI, CT skull base, PET-CT, video-EEG-monitoring	TLE due to right temporo-polar encephaloceles in the area of multiple temporo-polar bone defects. Multiple (right > left)	Resection of the encephaloceles, the amygdala and the uncus, latero-basal duraplasty with Tachosil	1A, 1 (56 months)
7	16, f	33.2	3b, 4	Psychic auras and dyscognitive seizures since 4 years	MRI, CT skull base, fMRI, PET-CT, video-EEG-monitoring	TLE due to right temporal encephalocele 1 right	Resection of the temporal pole, removal of the encephalocele and coverage of the temporo-polar skull base defect	1A, 1 (50 months)
8	25, m	24.3	no	Epigastric auras, dyscognitive and bilateral tonic-clonic seizures since 1 year	MRI, CT skull base, PET-CT, video-EEG-monitoring	Drug-resistant left TLE with two temporo-polar encephaloceles 2 left	Resection of the left temporal pole including two temporo-polar encephaloceles and resection of the amygdala while sparing the hippocampus	1A, 1 → 4B, 5 (72 months)
9	45, f	36.2	1, 3a, 3c, 4	Dyscognitive seizures and bilateral tonic-clonic seizures since 15 years	MRI, CT skull base, fMRI, video-EEG-monitoring	SEEG-proven TLE due to left temporo-basal Meningoencephalocele 2 (1 left, 1 right)	Resection of the left tempo-basal cortex and the meningoencephalocele	3B, 4 (13 months)
10	48, f	41.7	1, 3a, 3c, 4	Somatosensory auras and tonic-clonic seizures since 4 years	MRI, CT skull base, video-EEG-monitoring	SEEG-proven TLE due to right temporal pole Meningoencephalocele 1 right	Resection with removal of right temporal pole, meningoencephalocele and amygdalohippocampectomy	1A, 1 (34 months)
11	43, f	35.9	1, 3a, 3c, 3d, 4	Dyscognitive and bilateral tonic-clonic seizures since 10 years	MRI, CT skull base, Video-EEG-monitoring, fMRI, PET-CT	SEEG-proven TLE due to the bilateral sphenoidal meningoencephaloceles 2 (1 right, 1 left)	Resection of the left temporal pole and removal of a lateral and medial meningoencephalocele	1A, 1 (23 months)
12	22, m	28.3	no	Somatosensory auras, dyscognitive seizures and bilateral tonic-clonic seizures since 2 years	MRI, CT skull base, video-EEG-monitoring, fMRI, PET-CT	TLE due to the right temporal pole meningoencephalocele 1 right	Resection of the right temporal pole as well as the meningoencephalocele	3B, 2 (12 months)
13	49, m	34.2	3c, 3d, 4	Unspecific auras, epileptic arousals, dyscognitive seizures and bilateral tonic-clonic seizures since 11 years	MRI, CT skull base, video-EEG-monitoring, fMRI, PET-CT	SEEG-proven TLE due to the left temporal pole meningoencephalocele Multiple (left>right)	Resection of the left temporal pole as well as the meningoencephalocele	4C, 5 (13 months)
14	22, m	26.9	no	Unspecific auras, dyscognitive seizures and bilateral clonic seizures since 6 years	MRI, CT skull base, video-EEG-monitoring, fMRI, PET-CT	TLE due to the left temporal pole und temporobasal meningoencephaloceles 2 left	Resection of the meningoencephaloceles left temporo-basal and temporo-polar	1A, 1 (12 months)
15	16, m	21.7	no	Unspecific auras and dyscognitive seizures since 2 years	MRI, CT skull base, video-EEG-monitoring	TLE due to left temporopolar meningoencephalocele 1 left	Resection of the left temporal pole including the meningoencephalocele	1A, 1 (3 months)

BMI: body mass index: CSF: cerebrospinal fluid; CT: computed tomography; EEG: electroencephalography; f: female; fMRI: functional magnetic resonance imaging; IIH: idiopathic intracranial hypertension; m: male; MRI: magnetic resonance imaging; PET: positron emission tomography; SEEG: stereoelectroencephalography.

Table 3.

Rebound intracranial hypertension (RIH).

		BMI	MRI signs of IIH	Diagnosis/CSF opening pressure		RIH symptoms	Treatment	Follow up
1	49, f	25.4	–	Leptomeningeal hemosiderosis Cochlea implant device/14 cm	Ventral dural tear Th 7/8	Headache, blurred vision, double vision, CSF pressure 38 cm H2O	Lumbar drainage of 30 ml CSF Acetazolamide 2× 500 mg/day	Intermittent double vision No follow-up MRI
2	47, f	38.7	–	SIH/10 cm H2O	Ventral dural tear Th 10/11	Headache while lying	Acetazolamide 3× 250 mg/day for 2 weeks	Resolution of RIH symptoms No follow-up MRI
3	64, f	25.3	–	Leptomeningeal hemosiderosis/17 cm H2O	Ventral dural tear Th 2/3	Headache while lying dizziness	Acetazolamide 3× 250 mg/day for 1 week	Resolution of RIH symptoms MRI: resolution of SIH signs, no IIH signs
4	39, m	44.6	1, 3a, 3d	SIH/punctio sicca	Ventral dural tear Th 1/2	Headache while lying	Acetazolamide 3× 250 mg/day for 1 week	Resolution of RIH symptoms MRI: Discrete IIH signs
5	35, f	33.6	1, 3a, 4	SIH/16 cm H2O	Ventral dural tear Th 1/2	Headaches while lying papilledema left	Acetazolamide 3× 250 mg/day for 1 week	Resolution of RIH symptoms MRI: IIH signs
6	66, m	27.5	1	SIH with frontotemporal brain sagging syndrome/4 cm H2O	CSF venous fistula Th 9/10 right	Dizziness, vertigo	Acetazolamide 2× 500 mg/day for 3 months	Marked improvement of SIH symptoms, residual hypacusis MRI: marked improvement of SIH signs, no IIH signs
7	41, f	23.3	3a	SIH/2 cm H2O	Ventral dural tear Th 1/2	Headache while lying dizziness 27 cm H2O	Acetazolamide 3× 250 mg/day for 1 week	Resolution of RIH symptoms MRI: IIH signs

BMI: body mass index: CSF: cerebrospinal fluid; f: female; IIH: idiopathic intracranial hypertension; m: male; MRI: magnetic resonance imaging; SIH: spontaneous intracranial hypotension.

Spontaneous rhinoliquorrhoea

A total of six patients underwent computed tomography (CT) and MRI cisternography in order to locate an intracranial CSF leak. Three patients each were studied with fat-saturated 2D T1-weighted spin echo sequences (slice thickness 3 mm) or with almost isotropic sagittal T1-weighted black-blood and fat-saturated compressed sensing 3D Sampling Perfection with Application optimized Contrasts using different flip angle Evolution (SPACE) sequences (slice thickness 0.5 mm).^14–19 Note that a part of this cohort has been described previously. ¹⁹

Four of six patients with spontaneous rhinoliquorrhoea showed MRI signs of IIH and three patients (all women) were obese with a body mass index (BMI) >30 kg/m² (Figure 1). Of note, in one obese woman, rhinoliquorrhoea recurred after 3 years (Table 1: No. 1), in two women with obesity (Table 1: No. 2) or overweight (Table 1: Np. 5), surgical repair of a cribiform plate leak had to be performed twice.

Figure 1.

Sagittal (a) and axial (d) T2-SPACE images in a 54-year-old obese woman (body mass index (BMI) 42 kg/m²) with partially empty sella ((a): arrow) and protrusions of the subarachnoid space on the left side ((d): arrow). Note that these arachnoid pits are visualised in a skull base-computed tomography (CT) ((f): arrow). Gadolinium-enhanced ((b) and (e)) better than CT cisternography (c) shows a low lying cribiform plate (Keros type 3) and a leak on the left side ((b) and (c): arrow). The leak was surgically treated via a bifrontal approach. Rhinoliquorrhoea was initially stopped but recurred three years later.

Antero-inferior temporal lobe meningoencephaloceles

A total of 15 patients undergoing presurgical work-up for TLE and suspected meningo-encephaloceles were finally operated on. Note that a part of this cohort has been described previously. ⁷ In six patients, epileptogenicity of a meningo-encephalocele was proven by stereoelectroencephalography (SEEG) (Figure 2). Seven of 15 (47%) patients had a BMI>30 kg/m² and six patients also showed MRI signs of IIH (40%). Postsurgical seizure freedom (Engel 1A, Wieser 1) after a period of 3–52 months was reached in 10 patients (66.6%) irrespective of BMI, MRI signs of IIH or uni- or bilateral meningo-encephaloceles (Table 2).

Figure 2.

A 48-year-old obese woman (body mass index (BMI) 41.7 kg/m²) suffered from temporal lobe seizures since 4 years. Stereoelectroencephalography (SEEG) recordings from 10 depth electrodes showed a seizure origin in the right-sided anterior temporal lobe. Magnetic resonance imaging (MRI) with coronal T2-weighted turbo spin echo (TSE) images showed a small meningocele ((b): arrow) which resulted in two pits in the skull base computed tomography (CT) ((a): arrow). The patient was treated with anterior temporal lobectomy and amygdalophippocampectomy, the small meningocele was disconnected ((c): arrow). Three years later was seizure-free. Other idiopathic intracranial hypertension (IIH) signs such as empty sella ((d): arrow) or the protrusion of an arachnoid into the transverse sinus remained constant ((e) and (f): arrow)

RIH

A total of 162 patients with symptoms suggestive of SIH underwent a standardised work-up including MRI head, MRI spine, dynamic myelography, CT myelography and in patients with confirmed extrathecal contrast dynamic CT myelography and/or dynamic subtraction myelography, respectively. ²⁰ Forty-four patients finally underwent surgery: In seven patients (16%) with a ventral leak confirmed by surgery (n = 6) or with a CSF venous fistula (n = 1) the headache type changed immediately after surgery. Headache occurred while lying down and was accompanied by dizziness in four patients. Acetazolamide (250 mg three times a day) was prescribed for 1–2 weeks which led to the resolution of symptoms in all patients. MRI was performed in the further follow-up in five patients and showed IIH signs in two patients (Figure 3). Three patients had a BMI>30 kg/m² (Table 3).

Figure 3.

Rebound intracranial hypertension (RIH) in a 35-year-old, obese woman (body mass index (BMI) 33.6 kg/m²) in which a ventral dural tear at the level Th1/2 was surgically ligated. After surgery she complained of headache while lying down, fundoscopy showed a papilloedema of the left eye. (a)–(c) are images before, (d)–(f) images 2 months after surgery. At this time, RIH symptoms had already resolved. Note a partial empty sella with compression of the pituitary gland anteriorly to the pituitary stalk ((d): arrow) compared to an enlarged (hyperaemic) gland before ((a): arrow). The perioptic cerebrospinal fluid (CSF) spaces are now enlarged ((e): arrows), and the transverse sinus is distinctly smaller ((c) and (f): arrow).

Discussion

The annual incidence of IIH in industrialised countries is strongly increasing: From 1.0/100.000 in 1990, 2.3/100.000 in 2003 to 7.8/100.000 in 2017. ¹⁹ , ²² The incidence may be even higher when patients presenting with spontaneous CSF rhinorrhoea, TLE due to temporal lobe meningo-encephaloceles or RIH are considered. These patients do not complain of headaches, transient visual obscurations, and/or visual loss or blurring, and it is rather the MRI findings that are suggestive of the diagnosis of IIH. However, as imaging is typically adapted to the specific clinical presentation, relevant MRI sequences such as MR venography to prove transverse sinus stenosis are not acquired. Moreover, the CSF pressure is rarely measured.

Patients with spontaneous rhinoliquorrhoea

For evaluating patients with suspected intracranial CSF leaks the most widely accepted method is CT cisternography. As adjacent bony structures and contrast-enhanced CSF have similar density values intrathecal injection of gadolinium although not Food and Drug Administration (FDA)-approved (Figure 1) is a valuable alternative.^14–19 Gadolinium cisternography provides a high contrast between bony structures, air cell structures, and CSF diluted with gadolinium as well as a high spatial resolution when a T1-weighted sequence with an almost isotropic 3D resolution (0.5 × 0.5 × 0.6 mm³) is acquired. ¹⁹ All patients in this series have been studied with CT and MR cisternography: Three of six patients with spontaneous rhinoliquorrhoea but none of five patients with iatrogenic rhinoliquorrhoea studied in the same period showed MRI signs of IIH. Three of six patients had a BMI>30 kg/m² indicating that IIH promotes the development of spontaneous intracranial CSF leaks.

Patients with temporal lobe meningo-encephaloceles

That antero-inferior temporal lobe meningo-encephaloceles can cause TLE has been described with larger series since 2015 (Figure 2).^7–11 The prevalence of temporal lobe meningo-encephaloceles causing TLE is in the range of 5–10%. ²³ However, the definition of a meningo-encephalocele is not straightforward. Encephaloceles are protrusions of brain through focal bony defects. Meningoceles are focal bony dehiscences containing CSF but not brain parenchyma. They likely represent arachnoid granulations protruding into the overlying bone. The number and size of arachnoid granulations are larger in IIH patients compared to controls, however so-called arachnoid pits are found in 20% and temporal lobe encephaloceles in 5% of asymptomatic controls, respectively.^24–26 In this series, we only analysed operated patients, in six patients the epileptogenicity of an encephalocele was proven with SEEG. Nine of 15 patients (60%) showed MRI signs of IIH, seven patients (44%) had a BMI>30 kg/m² and six had both of these again emphasising the correlation between IIH and obesity in some, but not all, patients.

Patients with spontaneous rhinorrhoea often also have temporal lobe meningo-encephaloceles (Figure 1). Why some patients with MRI signs of IIH develop TLE, others rhinoliquorrhoea and others classical IIH symptoms has been explained with the glymphatic system allowing to drain the CSF along paravascular channels of the optic nerve sheaths more effectively in older than in younger patients.^27–30 Of clinical note is that rhinoliquorrhoea may persist or recur when the underlying cause IIH is not sufficiently treated. ²⁸ And epileptic seizures originating from the contralateral temporal pole may arise when one meningo-encephalocele is disconnected. As bilateral lesions are present in 30–40% of cases, ⁷ , ⁸ , ²⁶ this could imply to also treat the IIH. ³¹

Female gender and obesity are accepted risk factors for IIH. Weight reduction by low-calorie meal replacement or even bariatic surgery may improve classical symptoms such as headaches and vision.^32–34 Whether these are helpful following the surgical closure of a spontaneous CSF leak (to avoid a recurring leak) or in TLE patients due to encephaloceles (to reduce seizures) remains to be proven.

The pathological mechanisms that link female gender, obesity, and IIH are unclear, as IIH is relatively rare, while obesity is common. That centrally distributed adiposity transmits pressure and thereby generates raised Intracranial Pressure (ICP) is questionable, as few obese patients have elevated ICP. Hormonal mechanisms and dysregulation of adipokines and cytokines are pathogenic in dysregulating ICP, the latter, however may merely be a consequence of the disease.^35–37

Patients with rebound intracranial hypertension (RIH)

RIH following treatment of SIH was first reported in 1996 in a patient who underwent surgical repair of a leaking thoracic meningeal diverticulum. ³³ RIH is defined as a different headache form (‘reverse orthostatic headache’) responsive to acetazolamide. The most common scenario is that a (sub)occipital SIH headache transforms to a frontal high-pressure headache. ¹² , ¹³ Most patients also have new nausea and/or vomiting and complain of new blurred vision. ¹³

RIH occurs in about one-quarter of patients following treatment of SIH, most often within 72 h but in rare cases up to 1 month following treatment. RIH occurs more often in women, at a younger age, and when imaging shows extradural CSF, possibly reflecting the severity of the underlying spinal CSF leak and the potential for significant shifts in CSF dynamics following treatment. ¹² Funduscopic examination shows papilloedema in a minority of patients only, CSF pressure is often between 20–25 cm H₂O, but distinctly higher than before treatment. ¹²

While SIH patients typically have a low BMI, it is interesting to note that three patients in our RIH group had a BMI>30 kg/m². ³⁸

Imaging findings have rarely been described in RIH patients. ¹² However, as it is a diagnostic criterion in IIH it may also help to support the diagnosis RIH (Figure 3).

Conclusions

We have described less widely known entities that can present with MRI signs of IIH. MRI findings should guide the clinician to consider IIH when patients develop spontaneous rhinoliquorrhoea or TLE due to temporal lobe meningo-encephaloceles. Further work has to be done to elucidate why and which SIH patients develop RIH.