Cysticercosis presenting as a mass lesion at foramen of Monro.

Cysticercosis is a parasitic infestation that commonly affects the central nervous system. This is a report of computed tomography findings in a patient with a noncalcified cyst causing asymmetric lateral ventricular obstruction at the foramen of Monro. The lesion was isodense and uniformly enhancing, an unusual finding possibly related to presentation early in the course of the disease. This disease should be considered in the differential diagnosis of the lesions at the foramen of Monro in patients with appropriate residence or travel history.     

Prenatal diagnosis and postnatal management of congenital unilateral hydrocephalus for stenosis of the foramen of Monro

Congenital hydrocephalus and ventriculomegaly can be diagnosed reliably with prenatal ultrasound and Magnetic Resonance Imaging (MRI). Unilateral hydrocephalus is uncommon, and the prognosis depends on etiology and postnatal management. Here, we present a case of a 32-years-old woman with prenatal diagnosis of unilateral hydrocephalus associated with stenosis of the foramen of Monro. Unilateral hydrocephalus is an uncommon feature that can be detected prenatally on ultrasound and MRI. In case of isolated stenosis of the foramen of Monro prognosis is good.     

Unusual small choroid plexus cyst obstructing the foramen of monroe: case report

This is a case report of unusual case of choroid plexus cyst at the right foramen of Monro in the anterior third ventricle that caused unilateral obstructive hydrocephalus. The value of small-FOV thin-section MR imaging in the diagnosis of small lesions of the foramen of Monroe is demonstrated. The immunohistochemical findings in choroid epithelial cysts in comparison with those of other types of cysts at this location are discussed.     

The medial posterior choroidal artery as an indicator of masses at the foramen of monro

Summary The angiographic findings in five cases of tumors at the foramen of Monro are presented. Characteristic changes in the course and configuration of the medial posterior choroidal artery are described.Supported in part by USPHS Grant #5-T01-NS05646 NSRB.Presented at the annual meeting of the American Society of Neuroradiology, Vancouver, British Columbia, Canada, June 1975     

中枢神经细胞瘤的MRI征象及其鉴别诊断

目的分析中枢神经细胞瘤（cN）的MRI特征,并与孟氏孔附近其他肿瘤进行鉴别诊断,以提高中枢神经细胞瘤术前诊断的正确性。方法回顾性分析7例经病理证实的中枢神经细胞瘤（CN）病例,并与16例孟氏孔周围的其他侧脑室肿瘤影像学特征进行比较以确定此类肿瘤的MRI特征。我们对肿瘤的影像学特征的预测值,包括附着于透明隔、肿瘤的异质性及肿瘤周围囊肿的条索状改变等,进行二元虚拟变量的多元回归分析。结果7例中枢神经细胞瘤实质部分均呈不均匀信号,其中6例呈皂泡样或是海绵状改变。病灶外围可见囊肿及条索状结构与侧脑室壁、透明隔、胼胝体相连或是粘连,这些条索状结构和囊肿与侧脑室壁形成具有特征性改变的周边囊肿一条索征象外观,在与孟氏孔附近的其他肿瘤的鉴别诊断实验中,具有特征性的周边囊肿一条索征象有较大的诊断特异性和准确性。结论识别MRI上CN外周囊性改变及条索状改变与侧脑室壁之间形成的特征性征象,有助于提高中枢神经细胞瘤术前诊断的正确性。     

Venous variations in the region of the third ventricle: the role of MR venography

In this study, we examined the anatomical variations of the subependymal veins in the region of the foramen of Monro and the third ventricle by MR time of flight (TOF) venography. Fifty healthy subjects, ten patients with third-ventricle tumors, and four patients with lateral-ventricle tumors were included in the study. The courses of the anterior septal vein (ASV), thalamostriate vein (TSV), and internal cerebral vein (ICV) were studied. The proximity of the venous angle, the false venous angle, and the ASV–ICV junction to the posterior margin of the foramen of Monro was measured. In 69 (53.9%) sides, the ASV–ICV junction was located at the venous angle and at the posterior margin of the foramen of Monro. In 59 (46.1%) sides, the ASV–ICV junction was located beyond the foramen of Monro. Our study shows the high incidence of posteriorly located ASV–ICV junctions, which can be crucial in the planning of a better surgical approach. We strongly recommend that MR venography, which is a short radiological examination, be used before one operates on third-ventricle and lateral-ventricle tumors.     

The interventricular extension of choroid plexus papillomas

Four cases of choroid plexus papilloma extending through the foramen of Monro are presented. All four patients were evaluated by contrast-enhanced CT and two of these were also evaluated by neurosonography. No other intraventricular tumor commonly extends through a ventricular outlet. The radiographic demonstration of this extension of an intraventricular mass through the foramen of Monro, cerebral aqueduct, or foramen of Luschka or Magendie represents an ancillary diagnostic sign of choroid plexus papilloma.     

中枢神经细胞瘤的CT与MRI诊断

目的:研究中枢神经细胞瘤(CNC)的CT与MRI影像特点,以提高对该病的认识。方法:回顾性分析经手术病理证实的CNC 5例,分析其临床CT与MRI表现。结果:本组病例中肿瘤均位于侧脑室透明隔,靠近Monro孔处,在CT上呈等或稍高密度,在MRI T1WI呈等或稍低信号,T2WI上呈不均匀高信号,增强后可见不均匀明显强化。肿瘤均可见囊变,边缘清晰。结论:青年人位于透明隔的肿瘤,应考虑CNC的诊断,CT与MRI有助于诊断此病,确定手术方案。     

中枢神经细胞瘤的影像学诊断

目的：探讨中枢神经细胞瘤的影像学诊断价值。方法：回顾性分析11例经病理证实的中枢神经细胞瘤患者的CT和MRI表现。结果：11例中枢神经细胞瘤均位于侧脑室前2/3、孟氏孔区,多呈不规则形,可见分叶,向两侧不对称生长,边界清晰,无或见有轻度脑水肿。CT多呈等或稍高密度阴影,其中可见囊变及钙化。MRI表现为T1WI呈等、稍低或稍高信号,T2WI呈等或稍高信号,肿块可见囊变、钙化或出血,CT和MRI增强扫描见病灶实性部分轻中度强化,囊变和钙化区无强化。结论：中枢神经细胞瘤的CT和MRI表现具备一定的特征性,有望在术前作出正确诊断。     

中枢神经细胞瘤的MRI、CT分析

目的:探讨中枢神经细胞瘤的影像学表现,以提高认识和诊断水平。方法:回顾性分析经手术病理证实的中枢神经细胞瘤8例的MRI、CT表现。结果:8例肿瘤均位于双侧侧脑室透明隔或第三脑室Monro孔处,分别向一侧或两侧侧脑室内生长,肿瘤呈不规则形,边缘清楚。CT平扫呈略高密度,密度不均匀,增强扫描轻度强化。MRI表现为略长T1WI、长T2WI信号,病灶内可见小的囊变灶,注射Gd-DTPA后,病变轻度强化。结论:中枢神经细胞瘤CT和MRI诊断具有一定的价值,尤其是MRI。     

Changes in size and magnetic resonance signal intensity of the cerebral CSF spaces during the cardiac cycle as studied by gated, high-resolution magnetic resonance imaging

In 1966, du Boulay demonstrated the pulsatile nature of CSF flow in the cerebral aqueduct by using air cineventriculography, which disturbs normal CSF dynamics by replacing part of the incompressible CSF with air. To investigate this phenomenon noninvasively, 35 normal volunteers were studied using high-resolution, cardiac-gated MR imaging. Specifically, we wished to document changes in size and configuration of the CSF spaces and the incidence and magnitude of signal loss (an indication of CSF motion) in these spaces as they related to time in the cardiac cycle. Changes in size and configuration were measurable in the third ventricle only (size increased during systole in seven of the 35 volunteers). Except for the lateral ventricles, some loss in signal intensity was seen in all CSF spaces at least during systole in all 35 volunteers--findings consistent with those of du Boulay. However, contrary to du Boulay's observations, asymmetric loss of signal, consistent with pulsatile CSF flow, was demonstrated at the level of the foramen of Monro in 15 of the 35 volunteers. Based on the pattern of flow void at the level of the foramen of Monro and on the expansion of the third ventricle during systole, we propose a theory of synchronous CSF flow at the foramen of Monro and aqueduct, which unifies our MR findings with du Boulay's cineventriculographic observations.     

Transient hydrocephalus due to movement of a clot plugging the aqueduct

A rare case of transient hydrocephalus is reported. A 64-year-old woman presented with headache. Computerized tomography (CT) scan revealed hydrocephalus with tiny blood clots in the left foramen of Monro and in the aqueduct. Six hours after the onset, the signs and symptoms disappeared spontaneously. The second CT showed improvement of the hydrocephalus with migration of the clot into the IV ventricle. Aqueductal trapping and releasing of the clot formed by bleeding from the choroid plexus located in the left foramen of Monro was suspected for the origin of the transient hydrocephalus.     

Duplication of a vertebral artery associated with epidermoid cyst of the posterior fossa

A case of a duplication of the left vertebral artery associated with a premedullary epidermoid cyst at the level of the foramen magnum is described. The close proximity of the two malformative lesions in the present case and the overlap of the periods when such developmental abnormalities can arise suggest that they might be causally linked. Received 31 January 1996; Revision received 18 March 1996; Accepted 6 June 1996     

Oligodendrogliomas of the lateral ventricle: computed tomography and angiography

Computed tomographic (CT) and angiographic findings in four cases of oligodendroglioma of the lateral ventricle are reported. CT showed a midline nodular intraventricular mass containing punctate calcifications and cysts. The tumors were slightly to markedly enhanced after the infusion of contrast media. Angiography showed slightly increased vascularity in the mass, and displacement of subependymal veins near the tumor. Oligodendrogliomas of the lateral ventricle are rare but should be included in the differential diagnosis of intraventricular tumors near the foramen of Monro.     

中枢神经细胞瘤二例的磁共振成像诊断并文献复习简

目的：探讨中枢神经细胞瘤（CNC）的磁共振MRI特征,提高对本病的认识。方法回顾性分析2例经手术、病理证实的CNC的MRI特点。结果2例肿瘤均位于侧脑室及透明隔区域,邻近透明隔近室间孔（Monro孔）,分别向一侧或两侧侧脑室内生长。2例病变在T1WI和T2WI序列上呈混杂信号伴多发小囊变区,并夹杂少许小斑点状长T1短T2信号（钙化）;其中1例病变周边可见血管流空影;增强扫描呈轻-中度不均匀强化。结论中青年患者Monro孔区域富血供占位性病变伴多发小囊变、钙化、周边流空影,应高度怀疑中枢神经细胞瘤。     

侧脑室中枢神经细胞瘤的影像分析

目的 :分析侧脑室中枢神经细胞瘤的CT和MRI表现。材料和方法 :回顾性分析经手术病理证实的中枢神经细胞瘤 5例 ,其中男 3例 ,女 2例。年龄 2 0～ 44岁 ,平均 30 4岁。CT检查 3例 ,MRI检查 4例。结果 :肿瘤位于脑室内前2 /3 ,边界清楚。CT平扫呈略高密度 ,增强扫描肿瘤增强不明显。MRI表现为略短T1,略长T2信号。本组 5例有 3例误诊为室管膜瘤 ,2例误诊为星形胶质细胞瘤。结论 :中枢神经细胞瘤影像学有特征性表现 ,CT和MRI是该病有效的检查手段。侧脑室前 2 /3处发生的肿瘤 ,鉴别诊断应考虑到中枢神经细胞瘤。     

Masses and malformations of the third ventricle: normal anatomic relationships and differential diagnoses

The third ventricle lies in the center of the brain. It is surrounded by critical nuclear structures (the hypothalamus and thalami) and important glandular structures (the pituitary and pineal glands). Although a wide array of pathologic processes may involve the third ventricle, most are extrinsic masses. By understanding the anatomic boundaries of the third ventricle and its relationship to adjacent structures, it is possible to create short lists of differential diagnoses. Third ventricle masses can be classified as arising in or immediately adjacent to one of five locations: anterior, posterior, inferior, foramen of Monro, and intraventricular. Anterior masses involve the optic and infundibular recesses, posterior masses affect or arise in the posterior commissure and pineal gland, and inferior masses involve or affect the ventricle floor. Masses may also arise at or adjacent to the foramen of Monro or entirely within the third ventricle. Of the intraventricular masses, chordoid glioma-a rare low-grade primary neoplasm-is unique to the third ventricle. Congenital malformations of the third ventricle are uncommon and are most often noted during childhood. Most commonly, these anomalies represent malformations of the neurohypophysis, which may manifest as hormonal abnormalities, or stenosis of the aqueduct of Sylvius, which manifests as dilatation of the third and lateral ventricles (hydrocephalus).     

Unilateral hydrocephalus: prenatal sonographic diagnosis

We studied six cases of unilateral hydrocephalus detected prenatally to analyze the sonographic features of the abnormality and to determine the cause and clinical outcome. In all cases, third-trimester sonograms showed marked unilateral lateral ventriculomegaly (mean atrial width, 4.4 cm) and normal contralateral lateral, third, and fourth ventricles. Five of the six cases had marked thinning of the cortical mantle on the affected side and shift of midline structures to the contralateral side. The causes of unilateral hydrocephalus were agenesis or stenosis of the foramen of Monro in three cases, transient obstruction of the foramen in one fetus with an intraventricular hematoma, underlying brain dysplasia in one fetus with a variant of holoprosencephaly, and undetermined in one case. All six neonates had placement of a ventriculoperitoneal shunt catheter; four of these have had normal cognitive development at follow-up. The remaining two infants have moderate to severe developmental impairment. Unilateral hydrocephalus is a rare anomaly that can be recognized by prenatal sonography. Even though unilateral ventriculomegaly may be marked, early diagnosis and treatment may result in a favorable clinical outcome.     

Congenital constriction of the foramen of Monro

Summary We report two cases of hydrocephalus in adults. The radiological investigations and direct inspection during surgery in one of the cases indicate that the hydrocephalus is caused in both cases by a benign stricture in the region of the foramen of Monro and that this constriction is congenital. This origin of hydrocephalus has not been reported previously in adults.     

Intracranial tuberous sclerosis in infancy

Transfontanelle sonograms and CT scans of the brain were obtained in 2 infants with tuberous sclerosis. Each modality showed typical subependymal nodules in both infants, as well as a large mass adjacent to the foramen of Monro in one of them; in the other, peripheral cortical tubers were clearly outlined with CT but not detected by ultrasound.