Intracranial hypertension secondary to giant arachnoid granulations

Multimodality imaging in cerebral venous thrombosis: a synopsis for emergency radiologist

Cerebral venous thrombosis (CVT) is an uncommon but potentially fatal condition which presents with a wide range of symptoms. Some of these presenting features are vague thus contributing to the delay in diagnosis. A prompt diagnosis and initiation of appropriate therapy are therefore of paramount importance. In this pictorial, we have tried to illustrate the direct and indirect imaging features of CVT in detail on multiple imaging modalities, along with the potential pitfalls of imaging.

Supracerebellar infratentorial resection of a torcular lesion causing fulminant intracranial hypertension: illustrative case

BACKGROUND

Venous sinus stenosis has been implicated in intracranial hypertension and can lead to papilledema and blindness. The authors report the unique case of a cerebellar transtentorial lesion resulting in venous sinus stenosis in the torcula and bilateral transverse sinuses that underwent resection.

OBSERVATIONS

A 5-year-old male presented with subacute vision loss and bilateral papilledema. Imaging demonstrated a lesion causing mass effect on the torcula/transverse sinuses and findings of increased intracranial pressure (ICP). A lumbar puncture confirmed elevated pressure, and the patient underwent bilateral optic nerve sheath fenestration. Cerebral angiography and venous manometry showed elevated venous sinus pressures suggestive of venous hypertension. The patient underwent a craniotomy and supracerebellar/infratentorial approach. A stalk emanating from the cerebellum through the tentorium was identified and divided. Postoperative magnetic resonance imaging showed decreased lesion size and improved sinus patency. Papilledema resolved and other findings of elevated ICP improved. Pathology was consistent with atrophic cerebellar cortex. Serial imaging over 6 months demonstrated progressive decrease in the lesion with concurrent improvements in sinus patency.

LESSONS

Although uncommon, symptoms of intracranial hypertension in patients with venous sinus lesions should prompt additional workup ranging from dedicated venous imaging to assessments of ICP and venous manometry.

Giant Arachnoid Granulations: A Systematic Literature Review

Giant arachnoid granulations (GAGs) are minimally investigated. Here, we systematically review the available data in published reports to better understand their etiologies, nomenclature, and clinical significance. In the literature, 195 GAGs have been documented in 169 persons of varied ages (range, 0.33 to 91 years; mean, 43 ± 20 years; 54% female). Prior reports depict intrasinus (i.e., dural venous sinus, DVS) (84%), extrasinus (i.e., diploic or calvarial) (15%), and mixed (1%) GAG types that exhibit pedunculated, sessile, or vermiform morphologies. GAG size ranged from 0.4 to 6 cm in maximum dimension (mean, 1.9 ± 1.1 cm) and encompassed symptomatic or non-symptomatic enlarged arachnoid granulations (≥1 cm) as well as symptomatic subcentimeter arachnoid granulations. A significant difference was identified in mean GAG size between sex (females, 1.78 cm; males, 3.39 cm; p < 0.05). The signs and symptoms associated with GAGs varied and include headache (19%), sensory change(s) (11%), and intracranial hypertension (2%), among diverse and potentially serious sequelae. Notably, brain herniation was present within 38 GAGs (22%). Among treated individuals, subsets were managed medically (19 persons, 11%), surgically (15 persons, 9%), and/or by endovascular DVS stenting (7 persons, 4%). Histologic workup of 53 (27%) GAG cases depicted internal inflammation (3%), cystic change consistent with fluid accumulation (2%), venous thrombosis (1%), hemorrhage (1%), meningothelial hyperplasia (1%), lymphatic vascular proliferation (1%), and lymphatic vessel obliteration (1%). This review emphasizes heterogeneity in GAG subtypes, morphology, composite, location, symptomatology, and imaging presentations. Additional systematic investigations are needed to better elucidate the pathobiology, clinical effects, and optimal diagnostic and management strategies for enlarged and symptomatic arachnoid granulation subtypes, as different strategies and size thresholds are likely applicable for medical, interventional, and/or surgical treatment of these structures in distinct brain locations.

State of the Art: Venous Causes of Pulsatile Tinnitus and Diagnostic Considerations Guiding Endovascular Therapy

Venous variants and pathologic abnormalities are the most common causes of pulsatile tinnitus. These conditions include causes of turbulence within normally located veins and sinuses, and abnormally enlarged or abnormally located veins in close transmissive proximity to the conductive auditory pathway. Such disorders include pathologic abnormalities of the lateral sinus (transverse sinus stenosis and sigmoid sinus wall anomalies), abnormalities and variants of the emissary veins, and anomalies of the jugular bulb and jugular vein. Despite being the most common causes for pulsatile tinnitus, venous variants and pathologic abnormalities are often overlooked in the workup of pulsatile tinnitus. Such oversights can result in delayed patient care and prolonged patient discomfort. Advances in both cerebrovascular imaging and endovascular techniques allow for improved diagnostic accuracy and an increasing range of endovascular therapeutic options to address pulsatile tinnitus. This review illustrates the venous causes of pulsatile tinnitus and demonstrates the associated endovascular treatment. © RSNA, 2021.

Giant arachnoid granulation in a child with benign intracranial hypertension: an unusual case

CASE PRESENTATION

A 6-year-old girl complained of diplopia and headache over a 2-week period after sustaining a minor head injury. Her neurological examinations were normal, but visual examination identified bilateral papilledema. Magnetic resonance imaging of the brain revealed a protruding nodular lesion causing compression within the anterior superior sagittal sinus in the midline, showing high signal intensity on T2-weighted imaging (T2WI) and low signal intensity on T1WI, similar to that of cerebrospinal fluid. Enhanced T1WI showed irregular narrowing of the anterior superior sagittal sinus adjacent to this lesion. The cortical vein drained to the frontal pole of the arachnoid granulation lesion and into the superior sagittal sinus. No other parenchymal abnormality was noted. A lumbar puncture showed increased opening pressure (30 mmHg), and the laboratory findings were normal. Based on the imaging and clinical findings, benign intracranial venous hypertension with giant arachnoid granulation was diagnosed. The patient's symptoms were reduced satisfactorily following daily treatment with 750 mg acetazolamide.

CONCLUSION

We report a case of giant arachnoid granulation involving the anterior superior sagittal sinus in a 6-year-old girl who presented with benign intracranial hypertension. Clinicians should be aware of this rare anatomic variant to avoid unnecessary invasive procedures or examinations in children with benign intracranial hypertension.

Transverse venous sinus stenting for idiopathic intracranial hypertension: Safety and feasibility

Purpose Transverse sinus stenosis is commonly seen in patients with idiopathic intracranial hypertension. It is not clear whether it is the cause or the result of idiopathic intracranial hypertension. Stenting for idiopathic intracranial hypertension has been carried out in several prior series. Our goal was to evaluate the clinical and imaging follow-up results of patients with idiopathic intracranial hypertension that underwent stenting for this condition at our center. Materials and Methods We reviewed the clinical, venographic and follow-up imaging data in patients who underwent elective transverse sinus stenting during the period from 2011 to 2017. Results In total, 18 patients with idiopathic intracranial hypertension were identified. The mean lumbar cerebrospinal fluid opening pressure recorded was 408 mmH20. Overall, 16 patients met the inclusion criteria and underwent transverse sinus stenting. At venography, the mean pressure gradient across the dominant transverse sinus stenosis was 21 mmHg. The pressure gradient immediately after stenting in all of those measured was negligible. Following stenting, headaches improved in 10 of the 16 cases, with persistent headaches in four patients, one of which had persistent baseline migraines. All cases showed resolution of the papilledema on follow up. Follow-up imaging with computed tomography venography showed that the stents remained widely patent. The follow up in clinic was done for a mean period of 35.5 months. Follow up with computed tomography venography was done for a mean of 10.3 months. Conclusion Venous sinus stenting is a safe and effective procedure. It relieves papilledema in all cases and improves headaches in most cases.

Imaging of the Central Skull Base

The skull base is a complex bony and soft tissue interface that is divided anatomically into compartments. This article will focus specifically on the central skull base, which has a complex embryologic development and anatomy. Multiple entities from notochord remnants, neoplasm, infection, and other abnormalities may occur, and imaging is critical for depicting skull base pathology.

Idiopathic intracranial hypertension

Background

Idiopathic intracranial hypertension or pseudotumour cerebri is primarily a disorder of young obese women characterised by symptoms and signs associated with raised intracranial pressure in the absence of a space-occupying lesion or other identifiable cause.

Summary

The overall incidence of idiopathic intracranial hypertension is approximately two per 100,000, but is considerably higher among obese individuals and, given the global obesity epidemic, is likely to rise further. The pathophysiology of this condition is poorly understood, but most theories focus on the presence of intracranial venous hypertension and/or increased cerebrospinal fluid outflow resistance and how this relates to obesity. A lack of randomised clinical trials has resulted in unsatisfactory treatment guidelines and although weight loss is important, especially when used in conjunction with drugs that reduce cerebrospinal fluid production, resistant cases remain difficult to manage and patients invariably undergo neurosurgical shunting procedures. The use of transverse cerebral sinus stenting remains contentious and long-term benefits are yet to be determined.

Conclusion

An understanding of the clinical features, diagnostic work-up and therapeutic options available for patients with idiopathic intracranial hypertension is important both for neurologists and ophthalmologists as visual loss maybe permanent if untreated.

Role of noncontrast head CT in the assessment of vascular abnormalities in the emergency room

Noncontrast CT of the head is a widely used noninvasive investigation for a variety of acute and chronic neurological conditions. Since CT head without contrast is usually the first and often the only investigation in the emergency room for many neurological symptoms, it is imperative to detect subtle vascular changes, which in many patients can be life-saving. The vascular abnormalities may present with increased density and/or size of the vessels, filling defects, and be associated with parenchymal and bony changes. In this article, we present examples of several vascular pathologies which can be identified on the noncontrast CT of the head, and learn imaging and interpretation techniques to help recognize what often are nebulous changes. While some of the findings are diagnostic by themselves and others subtle, any suspicious abnormality should be followed with dedicated vascular imaging such as CT/MR angiogram, venogram, or catheter angiogram for confirmation and better characterization.

Arachnoid granulations: a rare cause of lytic occipital bone lesion

Arachnoid granulation is often found incidentally in the dural sinuses and skull. It may also enlarge the dural sinus or inner table of the skull. We report a 46-year-old woman who presented with occipital headaches and arachnoid granulations in both transverse sinuses and torcular herophili. Neurological examination was normal. Fundoscopic examination, visual fields and acuity were normal. The headache resolved with medical treatment. No intervention for these lesions was planned. The patient was followed up with magnetic resonance imaging studies.

Transverse sinus stenting for idiopathic intracranial hypertension: a review of 52 patients and of model predictions

BACKGROUND AND PURPOSE

Transverse sinus stenosis is common in patients with IIH. While the role of transverse sinus stenosis in IIH pathogenesis remains controversial, modeling studies suggest that stent placement within a transverse sinus stenosis with a significant pressure gradient should decrease cerebral venous pressure, improve CSF resorption in the venous system, and thereby reduce intracranial (CSF) pressure, improving the symptoms of IIH and reducing papilledema. We aimed to determine if IIH could be reliably treated by stent placement in transverse sinus stenosis.

MATERIALS AND METHODS

We reviewed the clinical, venographic, and intracranial pressure data before and after stent placement in transverse sinus stenosis in 52 of our own patients with IIH unresponsive to maximum acceptable medical treatment, treated since 2001 and followed between 2 months and 9 years.

RESULTS

Before stent placement, the mean superior sagittal sinus pressure was 34 mm Hg (462 mm H(2)0) with a mean transverse sinus stenosis gradient of 20 mm Hg. The mean lumbar CSF pressure before stent placement was 322 mm H(2)O. In all 52 patients, stent placement immediately eliminated the TSS pressure gradient, rapidly improved IIH symptoms, and abolished papilledema. In 6 patients, symptom relapse (headache) was associated with increased venous pressure and recurrent stenosis adjacent to the previous stent. In these cases, placement of another stent again removed the transverse sinus stenosis pressure gradient and improved symptoms. Of the 52 patients, 49 have been cured of all IIH symptoms.

CONCLUSIONS

These findings indicate a role for transverse sinus stent placement in the management of selected patients with IIH.

Unilateral transverse sinus stenting of patients with idiopathic intracranial hypertension

BACKGROUND AND PURPOSE

The pathophysiology of IIH remains unknown. TS stenoses have been observed in a high proportion of these patients. Stent placement to remove this potential obstruction to venous outflow has been proposed as a treatment option for patients with IIH refractory to medical treatment.

MATERIALS AND METHODS

The clinical presentation, treatment, and outcome of patients with refractory IIH evaluated for venous sinus stent placement at a tertiary care center was retrospectively reviewed.

RESULTS

Thirteen female patients with IIH were evaluated for sinovenous stent placement. Moderate sinus stenoses with normal intrasinus pressures were found in 3 patients and therefore stent placement was not performed. Ten patients had elevated intrasinus pressures (pressure gradient across stenosis, 11-50 mm Hg), which decreased following unilateral TS stent placement. Headaches improved or resolved in all stented patients. Papilledema resolved completely or almost completely in 8 patients and significantly improved in 2 patients. One patient developed optic atrophy. There were no major periprocedural complications.

CONCLUSIONS

In this small case series, restoring the patency of stenotic venous sinuses with a stent in patients with refractory IIH resulted in symptomatic improvement in all treated patients. The safety and efficacy of this procedure should be evaluated in a randomized controlled study to determine its role within the armamentarium of therapeutic options for patients with IIH.

Giant arachnoid granulation in a patient with benign intracranial hypertension

We report magnetic resonance (MR), computed tomography (CT) and angiographic imaging of an unusual giant arachnoid granulation in the superior sagittal sinus in a man with headache and vertigo. Intrasinus pressure measurements revealed a significant pressure gradient across the lesion. MR imaging is useful to identify giant arachnoid granulation and dural sinus thrombosis, whereas dural sinus pressure measurement in certain cases of giant arachnoid granulations can be used to evaluate the lesion as the cause of the patient's symptoms.

Large arachnoid granulations involving the dorsal superior sagittal sinus: findings on MR imaging and MR venography

BACKGROUND AND PURPOSE

Large arachnoid granulations (AG) within the dorsal superior sagittal sinus (SSS) have been incompletely characterized and can be confused with pathology. This report reviews the characteristics of these anatomic structures to establish common imaging features that allow differentiation from pathology.

MATERIALS AND METHODS

Twelve cases of large AG in the dorsal SSS are presented, identified by MR imaging. Signal intensity characteristics, size, location, venographic appearance, and association with adjacent venous and osseous structures were documented.

RESULTS

A defect in the dura of the SSS was seen in all of the cases communicating with the subjacent subarachnoid space. The average size of the AG was 8.1 x 9.4 x 10.0 mm (range, 4-19 mm). Ten produced calvarial remodeling, and 11 were in the direct vicinity of the lambda. On T2-weighted images, all were hyperintense to the brain. On T1-weighted images, 8 were hypointense and 4 were hypointense with mixed areas of isointense signal intensity. All of the AGs were associated with cortical venous structures entering the sinus. On MR venography, AGs appeared as focal protrusions into the sinus, displacing, distorting, and narrowing the sinus lumen. Seven patients had headache without other visible cause on MR imaging, and 4 were initially interpreted as thrombosis or tumor.

CONCLUSION

Large AGs can occur in the dorsal SSS. They are well-defined projections of the subarachnoid space into the sinus, can cause luminal narrowing and calvarial remodeling, and have typical signal intensity characteristics, position, and morphology differentiating them from other pathology. Association with patient symptoms is uncertain.

Dural arachnoid granulations and "giant" arachnoid granulations

Although arachnoid granulations (AGs) were already described by Antonio Pacchioni more than 300 years ago, two issues draw particular attention: first, the radiological features and differential diagnosis of the so-called giant AGs (GAGs) and second, their possible association with various disease processes. In order to evaluate the frequency, size and normal distribution of GAGs, an anatomical study of the dural sinuses was carried out. It involved all the autopsies performed during the period August 2002-February 2005 and included 651 cases: 306 females and 345 males, aged 13-99 years (mean 69 years). Grossly visible GAGs were identified in 24 cases: 7 females and 17 males, aged 45-92 years (mean 69 years). This is the largest population-based anatomical study on GAGs. It shows that GAGs, in general a rare finding (3.68%), are rather common in the adult population, especially in the elderly (aged >65 years) and that they can reach remarkable size (up to 2.5 cm and more in diameter). Giant AGs should be considered in the radiological differential diagnosis of intradural lesions, particularly those occurring in the transverse sinus of the elderly.

Giant arachnoid granulation misdiagnosed as transverse sinus thrombosis

We experienced a case of giant arachnoid granulation misdiagnosed as dural sinus thrombosis. A 66-year-old woman presented with a one month history of progressive occipital headache. Computed tomography angiography and cerebral angiography showed a round filling defect at the transverse sinus which was speculated as a transverse sinus thrombosis. Anticoagulation therapy was performed to prevent worsening of thrombosis for 2 weeks and then a Gadolinium-enhanced magnetic resonance imaging scan was performed. The filling defect lesion at the transverse sinus revealed a non-enhancing granule with central linear enhancement, which was compatible with giant arachnoid granulation. We checked the intrasinus pressure difference across the lesion the through the dural sinus in order to exclude the lesion as the cause of headache. Normal venous pressure with no significant differential pressure across the lesion was noted. Headache was treated with medical therapy.

Giant arachnoid granulation: differential diagnosis of acute headache

We present a case of intense, rapidly evolving headache clinically mimicking meningitis, subarachnoid haemorrhage or venous sinus thrombosis. Clinical examination, standard blood work and central nervous system studies were non-contributory and effectively ruled out these diagnoses. Cranial multidetector CT studies before and after application of intravenous contrast medium performed prior to lumbar tap disclosed a non-enhancing ovoid mass filling the superior sagittal sinus. This lesion posed a differential to venous sinus thrombosis, but ultimately fulfilled the criteria of a giant arachnoid granulation. The imaging characteristics and differential diagnosis of giant arachnoid granulations are discussed.

Imaging of cerebral venous thrombosis: current techniques, spectrum of findings, and diagnostic pitfalls

Cerebral venous thrombosis is a relatively uncommon but serious neurologic disorder that is potentially reversible with prompt diagnosis and appropriate medical care. Because the possible causal factors and clinical manifestations of this disorder are many and varied, imaging plays a primary role in the diagnosis. Magnetic resonance (MR) imaging, un-enhanced computed tomography (CT), unenhanced time-of-flight MR venography, and contrast material-enhanced MR venography and CT venography are particularly useful techniques for detecting cerebral venous and brain parenchymal changes that may be related to thrombosis. To achieve an accurate diagnosis, it is important to have a detailed knowledge of the normal venous anatomy and variants, the spectrum of findings (venous sinus thrombi and recanalization, parenchymal diffusion or perfusion changes or hemorrhage), other potentially relevant conditions (deep venous occlusion, isolated cortical venous thrombosis, idiopathic intracranial hypertension), and potential pitfalls in image interpretation.

Incidental giant arachnoid granulation

Arachnoid granulations may expand the dural sinuses or inner table of the skull. Although usually incidental, giant arachnoid granulations that are of sufficient size to fill the lumen of a dural sinus and cause local dilation or filling defects can rarely cause symptoms due to sinus obstruction leading to venous hypertension. This 31-year-old man presented with a 3-month history of progressive bifrontal headaches and a giant arachnoid granulation at the posterior superior sagittal sinus. Intrasinus pressure measurements showed no significant pressure difference across the lesion to explain the headaches, which were then treated medically. Dural sinus pressure measurement, in certain cases of giant arachnoid granulations, can be used to exclude the lesion as the cause of the patient's symptoms.

Cranial venous outflow obstruction and pseudotumor Cerebri syndrome

The pathophysiology of PTS including idiopathic intracranial hypertension or 'BIH', remains controversial. The older literature frequently referred to pathology in the cerebral venous drainage but more modern imaging techniques (CT and early MR) failed to reveal gross venous pathology. The role of impaired cranial venous outflow has recently been re-examined in the light of new methods of investigation (advanced MR venography and direct microcatheter venography with manometry) and of treatment (venous sinus stenting). Venous sinus obstruction in PTS is a more common factor in the pathogenesis of the condition than previously recognised. Venous obstruction may be primary, that is, it is the underlying aetiological factor in PTS. Venous sinus obstruction may also be secondary to raised CSF pressure which may exacerbate problems with intracranial compliance and raised CSF pressure. Early experience with venous stenting suggests that it may be a helpful treatment for patients with PTS but more experience and longer follow-up is required to define the subgroups of patients for whom it is most appropriate.