Abstract

Background:Pseudotumor cerebri (PTC), also known as idiopathic intracranial hypertension (IIH), is a condition associated with increased intracranial pressure (ICP) in the absence of radiographic findings such as mass lesions or cerebral edema.

Case Description:We describe a case of progressive headache and visual disturbances attributed to PTC that resulted from subacute superior sagittal sinus (SSS) stenosis by a metastatic tumor.

Conclusions:Venous outflow obstruction often presents with an acute symptomatology including infarcts, hemorrhages, and seizures, but only rarely does it cause the progressive development of raised ICP. The sinister presentation of our patient's pathology stemmed from local mass effect caused by a tumor that has hitherto not been reported to cause intracranial hypertension (IH) and was best elucidated using magnetic resonance venography (MRV).

Keywords: Idiopathic intracranial hypertension, papilledema, pseudotumor cerebri, renal cell carcinoma, venous sinus compression

INTRODUCTION

Pseudotumor cerebri (PTC), also known as idiopathic intracranial hypertension (IIH), is a condition associated with increased intracranial pressure (ICP) in the absence of radiographic findings such as mass lesions or cerebral edema.[ 11 ] The concept, introduced by Nonne in 1904, attempted to explain patients whose presentations suggested an intracranial tumor, but clinical courses appeared to preclude this diagnosis.[ 16 22 ] IIH can lead to headaches, diplopia, papilledema, and progressive vision loss. It can affect patients of any age or size, but is predominantly found in obese women of childbearing age. The pathophysiology of IIH is not entirely understood, but it has been associated with venous sinus obstruction. In fact, some studies indicate that transverse sinus stenosis is seen in over 90% of patients with IIH.[ 9 31 ] Magnetic resonance venography (MRV) has been shown to be an appropriate screening tool in these patients with a sensitivity of 93–100%.[ 6 9 ] There are conditions that mimic IIH,[ 7 25 26 37 ] but the presence of non-acute, non-thrombotic superior sagittal sinus (SSS) compression leading to signs and symptoms resembling IIH is rare. We describe a case of metastatic renal cell carcinoma (RCC) with SSS compression presenting as PTC.

CASE DESCRIPTION

VH is a 50-year-old male who presented to an outside facility with complaints of diplopia and headache initially diagnosed as PTC. He was evaluated by ophthalmology and neurology before being transferred to us for further tertiary management of sagittal sinus thrombosis. The patient described mild to moderate headaches of 3 weeks duration with blurry vision and 1 week of double vision that seemed to be exaggerated with rightward gaze. The patient had no pertinent past medical history. His physical exam was remarkable only for bilateral papilledema and subtle right-sided abducens nerve palsy. He was otherwise alert and oriented, with full muscle strength and without myelopathy or other cranial nerve findings. Of note, he had a palpable, compressible soft tissue mass over the vertex of his skull.

Imaging demonstrated a midline parietal extradural mass with erosion through the skull and into the subgaleal soft tissues. Magnetic resonance imaging (MRI)/MRV demonstrated depression of the SSS with local stenosis in that region. Computed tomography (CT) of the chest, abdomen, and pelvis yielded a 4-cm solid mass on the upper pole of the right kidney. The patient was initially started on a heparin drip by the primary team which was discontinued after definitive imaging was obtained and prior to a diagnostic lumbar puncture (LP). After an opening pressure of 51 cm H₂O by manometer in the lateral recumbent position confirmed intracranial hypertension (IH), he was placed on steroids and acetazolamide prior to discussion and recommendation of surgical resection.

A biparietal craniectomy was performed with gross total resection of the mass as demonstrated in preoperative and postoperative MRI scans [ Figure 1 ]. Recovery was uneventful with improvements in the patient's headache and gradual improvement in the patient's diplopia. A repeat LP performed 2 days after surgical resection showed an opening pressure of 4 cm H₂O and he was discharged on postoperative day number 3. Follow-up MRV demonstrated improved dural venous outflow [ Figure 2 ]. Ophthalmology follow-up 2 weeks later documented improvement in his papilledema and a repeat LP at that time gave an opening pressure of 21 cm H₂O. He received a cytoreductive right laparoscopic radical nephrectomy 6 weeks after his craniectomy. Twelve weeks after his cranial surgery, he presented with right leg pain related to a metastatic lesion to his femur necessitating prophylactic intramedullary nailing (IMN). Seven days later, X-ray demonstrated a minimally displaced pathologic fracture within the lytic lesion. Unfortunately, prior to receiving adjuvant radiation and chemotherapy, he was found deceased at home 1 week later from an unknown cause, approximately 4 months after presentation.

Figure 1

Preoperative (top) axial, coronal, and sagittal T1 magnetic resonance (MR) with contrast demonstrating an enhancing epidural mass extending through the calvarium and into the subgaleal space with compression of the superior sagittal sinus (SSS). Postoperative (bottom) axial, coronal, and sagittal T1 MR with contrast showing gross total resection of tumor with preservation of the SSS and resolution of sinus stenosis

Figure 2

Preoperative (left) magnetic resonance venography (MRV) demonstrating displacement and attenuation of the superior sagittal sinus (SSS). Postoperative (right) MRV demonstrating near resolution of SSS compression

DISCUSSION

The mechanism of increased ICP in IIH has not been fully elucidated, but the main concepts utilize the Starling resistor hypothesis and the Monro-Kellie doctrine. The latter doctrine explains that because the volume within the cranial compartment is fixed by the rigid confines of the skull, any increase in volume of one of the cranial constituents [brain matter, blood, and cerebrospinal fluid (CSF)] occurs at the expense of the others and the extent of which is at least in part determined by compensatory mechanisms in healthy individuals.[ 1 35 ] The former hypothesis elaborates that the collapsible terminal venous components reflect increased ICP to upstream dural sinuses and cerebral veins until they equal the ICP via a hydraulic mechanism.[ 5 33 ] In this case, it was assumed that impaired CSF reabsorption was secondary to the decreased CSF-venous pressure gradient across the arachnoid villi created by progressive stenosis of the sagittal sinus by the tumor.[ 32 ] Furthermore, the pressure response to increased CSF volume is not linear, but exponential.[ 5 ] Therefore, any increase in resistance to venous drainage will cause decreased upstream reabsorption of CSF leading to increased ICP, venous collapse, and exponential compounding until IH is developed.[ 33 ]

Papilledema and IH are well known phenomena that can occur with pathology of the dural venous sinuses.[ 9 17 ] In the setting of SSS involvement, symptoms of IH often occur in the context of thrombosis[ 28 ] and trauma,[ 12 34 ] but seldom due to direct compression. However, the SSS is rarely involved in an acute/subacute setting in the absence of clinical features suggesting cortical vein involvement such as seizures, paresis, venous infarcts, etc.[ 27 ] Most cases of SSS occlusion associated with neoplasms are thought to be attributed to thrombotic complications secondary to hypercoagulability states.[ 13 ] It must also be noted that removal of the offending pathology, whether it be thrombus or mass effect, may not always result in permanent cure of the IH.[ 32 ]

IH has rarely been described in the context of tumors compressing a dural venous sinus. Case reports include Ewing's sarcoma, plasmacytoma, neuroblastoma, disseminated carcinoma of the breast, and prostate cancer.[ 19 21 27 28 29 ] Tumors involving the posterior aspect of the SSS and/or the torcular herophili, dominant transverse sinus, or jugular foramen have a tendency to cause more symptomatic venous compression.[ 2 4 19 36 ] Though slow growing tumors such as meningiomas have been associated with “pseudotumor-like” symptoms,[ 32 ] IH attributable to neoplasms are more commonly seen with rapidly growing masses. Slower growing tumors with sinus compression are thought to be better tolerated because of the development of collateral venous drainage.[ 14 18 ] To our knowledge; however, IH has not been described with metastatic RCC.

Patients with brain metastases from RCC have a poor prognosis. The average survival time is 3 months if left untreated and 2–9 months if treated with whole brain radiation therapy (WBRT).[ 10 ] Unfortunately, metastatic RCC responds poorly to both WBRT and stereotactic radiosurgery (SRS).[ 10 ] Longer survival may be predicted by the absence of IH, few metastatic foci and extracranial metastasis. Surgical resection does seem to improve patient survival,[ 3 ] and in patients with a single brain lesion, good performance status, and limited/controlled systemic disease, surgery has been shown to confer an even greater survival benefit.[ 15 24 ] However, it must be noted that local failure rates approach 60%.[ 15 ] Cytoreductive nephrectomy may improve survival in patients with RCC, though brain metastasis is a known independent predictor of worse overall survival[ 23 ] and its use has become controversial in this setting.[ 30 ] New immunotherapies are showing promise for extending survival time.[ 8 ]

CONCLUSION

In conclusion, when patients present with signs and symptoms resembling PTC, we must reiterate that intracranial mass lesions must first be ruled out as IIH is, by definition, a diagnosis of exclusion.[ 20 ] In addition, there is increasing evidence that non-traumatic, non-acute symptoms indicative of IIH such as papilledema, headaches, and visual disturbances may suggest sinus involvement and early vascular imaging should strongly be considered. Though symptomatic venous sinus compression from an intracranial neoplasm is a rare phenomenon, surgical resection can help alleviate symptoms attributable to elevated ICP.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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