2023 年 10 巻 p. 327-330
We report a patient with idiopathic intracranial hypertension (IIH) with bilateral transverse sinus occlusion treated by a lumboperitoneal shunt. A 45-year-old woman presented with visual disturbance and chronic headache. Magnetic resonance (MR) venography and three-dimensional computed tomography angiography (3D-CTA) showed occlusion of both transverse sinuses. After the surgery, MR venography and 3D-CTA showed no blockages in both transverse sinuses. This phenomenon reveals that obstruction of the bilateral transverse sinus is a consequence of intracranial hypertension, not just a single cause. Since many patients have an obstruction or stenosis of the venous sinus, there are some reports of endovascular treatment. Sinus reconstruction is usually effective, but it is not effective in some cases. Reversal of sinus occlusion suggests that endovascular therapy for IIH is inadequate in some cases.
Idiopathic intracranial hypertension (IIH), called "pseudotumor cerebri," presents with symptoms of intracranial hypertension in the absence of a brain tumor.1) Although rare, IIH is common in women of childbearing age with obesity, and it can cause irreversible visual impairment due to optic papillary edema, requiring appropriate treatment.2) Surgical treatment for IIH refractory to drug therapy generally includes optic nerve sheath fenestration (ONSF) and cerebrospinal fluid (CSF) diversion surgery. Since many patients have an obstruction or stenosis of the venous sinus, there are some reports on endovascular treatment.3-5) In this report, we describe a case of IIH with bilateral transverse sinus obstruction in which a lumboperitoneal shunt (LPS) was performed, relieving the sinus obstruction. We report the case with some literature review.
A 45-year-old female with a body mass index (BMI) of 27.6 kg/m2 presented with complaints of headache and visual disturbance for one month. Optic nerve papillary edema was observed. Magnetic resonance (MR) imaging showed empty sella, flattening of the posterior part of the eyeball and sclera, and bilateral transverse sinus obstruction (Fig. 1A). No signs of tonsillar herniation were detected. Contrast-enhanced computed tomography (CT) showed arachnoid granules in the transverse sinuses (Fig. 2A). Three-dimensional computed tomography angiography (3D-CTA) revealed that transverse sinuses were interrupted by these arachnoid granules (Fig. 2B). Blood tests showed no elevation of D-dimer and no thrombus was suspected. Lumbar puncture revealed an increased intracranial pressure of 275 mmH2O. After 2 months of pharmacological treatment using acetazolamide and topiramate, headache and optic nerve papillary edema did not improve, so she underwent LPS. The Codman CERTAS plus programmable valve (Integra LifeSciences, Princeton, NJ, USA) was used, starting at 215 mmH2O. Immediately after the surgery, the patient had an orthostatic headache and tended to lie in bed. It suggested intracranial hypotension due to CSF over drainage. Therefore, we changed performance setting 8, a "Virtual Off" for a while. On the 4th day after surgery, the opening pressure was lowered to 215 mmH2O. She could elevate her head and live without headaches. Eleven days after surgery contrast-enhanced, CT revealed that the arachnoid granules still existed in transverse sinuses (Fig. 2C), but 3D-CTA revealed that those were not obstructed (Fig. 2D). Three months later, MR venography also showed that the obstruction of the transverse sinus was released (Fig. 1B). Thus, the optic papillary edema improved.
Magnetic resonance venography demonstrating transverse sinus occlusion before surgery (A) and sinus occlusion reversal after surgery (B).
(A) Contrast-enhanced computed tomography (CT) before surgery showing transverse sinus occluded by arachnoid granules. (B) Three-dimensional computed tomography angiography (3D-CTA) before surgery showing bilateral transverse sinus occlusion. (C) Contrast-enhanced CT showing no interception of transverse sinuses by the arachnoid granules after surgery. (D) 3D-CTA showing the opening of transverse sinuses after surgery.
Debates remain inconclusive as to whether or not IIH causes venous sinus stenosis. Treatment of IIH has been reported to include weight loss, oral acetazolamide,6) topiramate,7) and calcitonin gene-related peptide (CGRP) preparations.8) Surgical treatment of drug-resistant IIH has traditionally included ONSF and CSF diversion.9) Recently, venous sinus stenting (VSS) has been considered because venous sinus obstruction is a common finding in IIH. The improvement rate of VSS was 87.1%, 72.7%, 72.1%, and 72.1% for papillary edema, visual field disturbance, headache, and ophthalmoplegia, respectively.10) In this case, the venous sinus obstruction due to arachnoid granules was initially thought to result from IIH. Dural venous sinus stenosis can be classified as either intrinsic or extrinsic. Intrinsic stenoses are generally characterized by filling defects secondary to enlarged arachnoid granulations, fibrous septa, and brain herniations (encephaloceles), resulting in partial obstruction of the involved sinus. IIH may result in arachnoid granulations by obstructing sinus venous flow.11) In our case, the intra-sinus defects are CSF density on the CT image. MRI reveals that they are low intensity on T1-weighted images and high intensity on T2-weighted images. They are not enhanced with gadolinium. These findings are typical features of arachnoid granules. Therefore, we diagnosed the intra-sinus defects as arachnoid granules. It was then considered that the proliferation of arachnoid granules led to mechanical obstruction of the venous sinus, preventing CSF absorption. However, decreasing ICP by LPS reversed sinus obstruction. A similar case has been reported.12) In that case, smooth tapering compression of transverse sinuses appeared, and there were no arachnoid granules. In patients with IIH, venous sinus narrows between brain parenchyma and calvaria.13) This is classified into the extrinsic mechanism of sinus obstruction.13) Obesity, gender, and childbearing age must relate to the primary cause of ICP elevation, but it is still unknown. Primary causes elevate ICP and finally obstruct stenotic venous sinus due to arachnoid granules. These factors form a vicious circle.14) Extrinsic stenosis of the venous sinus is not considered an independent cause of IIH.14) Similarly, in the present case, the venous sinus obstruction is related to intrinsic and extrinsic factors. Venous sinus stenting can stop this vicious circle, but it must be ineffective to the primary cause. Therefore, it may be insufficient to reduce ICP in some cases. Approximately 10% of patients with IIH have no venous sinus obstruction.15) Thus, other mechanisms, except sinus obstruction, can cause symptomatic ICP elevation. Although VSS is usually effective, there are severe complications.16) A systematic review reported 2.3% severe complications, including acute subdural hematoma, subarachnoid hemorrhage, intracerebral hemorrhage, stent thrombosis, etc.10) Contralateral sinus stenosis after stenting is also reported. It is postulated that after stenting, the internal pressure in the contralateral transverse sinus decreases because most venous fluid flows again, passing through the stented dilated sinus. Then, the non-stented sinus shrinks and becomes occluded. The vicious circle of increased ICP restarts.17,18) In addition, oral antiplatelet medications are required after VSS.
Immediately after LPS, the symptoms of intracranial hypotension appeared despite high opening pressure. CSF leakage through the dural tear outside the shunt tube and habituation for longstanding conditions under intracranial hypertension must be monitored. We will change the opening pressure according to the patient's condition. LPS using a programmable valve can manage the patients' IIH. Also, LPS is effective in sinus obstruction. Although LPS is a symptomatic treatment, we can deal with the patient's condition using the programmable valve.
In some patients with IIH, obstruction of bilateral transverse sinuses may promote ICP elevation, but it may be a consequence of elevated ICP due to other causes. This phenomenon suggests that intervention for IIH may be inadequate in some cases. LPS is effective as a symptomatic treatment for venous sinus obstruction.
idiopathic intracranial hypertension (IIH), lumboperitoneal shunt (LPS), magnetic resonance (MR), three-dimensional computed tomography angiography (3D-CTA), optic nerve sheath fenestration (ONSF), cerebrospinal fluid (CSF), body mass index (BMI), computed tomography (CT), calcitonin gene-related peptide (CGRP), venous sinus stenting (VSS), intracranial pressure (ICP)
Informed consent for publication was obtained from the patient.
The authors and all co-authors have no conflicts of disclosure. Authors who are members of the Japan Neurosurgical Society have registered online for self-reported COI Disclosure Statement Forms.
