Huge arachnoid cyst in the posterior fossa: controversial discussion for selection of the surgical approach

Case report We report a case of a huge posterior fossa arachnoid cyst with hydrocephalus. This 15-month-old girl presented with macrocrania and psychomotor retardation. Magnetic resonance (MR) imaging demonstrated ventriculomegaly and a huge cystic lesion in the posterior fossa. A membranectomy was performed microscopically and the patient had a good postoperative course.Outcome Magnetic resonance imaging 1 year after the operation revealed adequate reduction in the size of the ventricle and cyst. Progressive macrocrania discontinued and normal development was obtained.     

成人后颅窝巨大蛛网膜囊肿的诊断与手术治疗

目的 探讨成人后颅窝蛛网膜囊肿的诊断和治疗方法.方法 回顾性总结分析10例成人后颅窝巨大蛛网膜囊肿的临床资料和手术效果,10例全部采取开颅囊壁切除造口粘连松解术,并使之与第四脑室和蛛网膜下腔交通,1例同期行颅内多发性硬膜下积液钻孔引流术.结果 所有病人术后恢复良好,出院前症状改善6例,无变化4例.术后1周常规复查头部MRI,囊肿缩小、小脑部分复位6例.3个月后随访复查头部CT,无囊肿复发.其中小脑完全复位4例,大部分复位6例;脑积水消失、脑室恢复正常4例,脑积水减轻6例;临床症状消失7例,好转3例.结论 开颅在显微镜下获得囊肿腔与脑室及蛛网膜下腔的交通是避免后颅窝巨大蛛网膜囊肿复发和治疗脑积水的关键,手术效果良好.     

Familial posterior fossa arachnoid cyst

Background Arachnoid cysts are a relatively common incidental finding on CT scans of the brain. They most commonly occur in the middle cranial fossa, where familial occurrence has rarely been reported. Posterior fossa arachnoid cysts are more unusual.Case histories We report the presence of quadrigeminal cistern arachnoid cysts in siblings.     

Facial nerve palsy in posterior fossa arachnoid cysts: report of two cases

Case report Two patients with a posterior fossa arachnoid cyst responsible for isolated facial nerve palsy are reported.Discussion The relationships between the cyst and the facial nerve and between the facial nerve palsy and the size variation of the cyst are discussed and documented by pre- and postoperative magnetic resonance imaging.     

Spontaneous disappearance of middle fossa arachnoid cyst after head injury

A case of middle fossa arachnoid cyst is presented, which disappeared after head injury. Five days after the trauma, CT scan revealed subdural fluid collection in addition to an arachnoid cyst in the middle fossa on the same side. As the subdural fluid resorbed, the cyst became smaller and disappeared on the follow-up CT scans without surgical intervention.     

中颅窝蛛网膜囊肿的临床特点及外科治疗

目的 探讨中颅窝蛛网膜囊肿的临床特点及不同术式对其治疗的临床疗效.方法 回顾性分析第四军医大学西京医院神经外科自2001年5月至2008年5月收治的352例中颅窝蛛网膜囊肿患者(占同期收住的颅内占位性病变患者的2.58%)的临床资料、手术方式及预后情况,其中男性发病率明显高于女性(男:女为4.1∶1),以左侧居多(左∶右为3.6∶1),324例行囊肿切除术,28例巨大囊肿行囊肿-腹腔分流术.结果 术后平均随访3个月～3年.头痛就诊患者中75例(58.59%)术后头痛完全消失,41例(32.03%)明显缓解.癫痫发作患者中8例术后发作频率明显减少或程度减轻.行为异常、注意力不集中或学习困难患者中11例术后改善明显.头围增大和颞部局限性隆起就诊者术后头围及局部隆起无明显变化.影像学复查显示囊肿完全消失者46例(13.07%),囊肿部分消失者257例(73.01%),囊肿无明显变化者49例(13.92%).结论 中颅窝蛛网膜囊肿的临床特点为男性、左侧多发,年龄愈小手术效果越好,手术仅部分切除壁层即可;囊肿巨大时行分流手术效果好,分流管以中低压为佳.

Abstract：

Objective o investigate the clinical characteristics of middle cranial fossa arachnoid cyst (MCFAC) and its therapeutic effects with different surgical methods. Methods Three hundred and fifty-two patients with MCFAC (about 2.58% of patients with intracranial space occupying lesion),admitted to our hospital from May 2001 to May 2008, were chosen in out study; their clinical data,surgical approach and prognosis were analyzed retrospectively. The gender ratio of patient with MCFAC adopted resection of arachnoid cyst and arachnoid cyst-peritoneal shunt was performed in 28 patients.Results Follow-up was performed for 3 months to 3 years. The headache completely disappeared in 75 patients (58.59%) and partial remission in 41 (32.03%) after the operation. The frequency and degree of seizures obviously decreased in 8 of the patients with MCFIAC. Eleven patients with dystropy,attention-deficit disorder or difficulty of learning got improvement. The head circumference and local skull eminentia was stable. The cyst disappeared completely in 46 patients (13.07%), partially in 257 (73.01%) and no changes in 49 (13.92%). Conclusion The clinical features of MCFAC is that it mainly occur in the left side of male. The younger the patient with MCFAC is, the better the treatment effect in the surgical intervention is. good outcome can be achieved by resection of the parietal layer of arachnoid cysts. The indication of shunt with meso-low pressure shunt system is for larger arachnoid cyst.     

Endoscopic approach to arachnoid cyst

A prospective study of 36 consecutive patients with congenital arachnoid cysts treated endoscopically is reported. There were 15 female and 21 male patients. The mean age at the time of diagnosis was 12.3 years (10 days to 38 years). Arachnoid cysts were located in the suprasellar region in 16 patients, the sylvian fissure in 11, the quadrigeminal cistern in 4 and the posterior fossa in 5. Endoscopic fenestration was combined with cysto-peritoneal shunting for 6 temporal cysts and with ventriculo-peritoneal shunting in 1 suprasellar cyst. Mean postoperative follow-up was 4.2 years (range 1–8 years). Follow-up imaging studies showed that 28 arachnoid cysts (77.8%) were obliterated after endoscopic procedures. Long-term clinical results were good in all patients, although the cysts of 8 patients were not reduced in size. There was no mortality or morbidity. We conclude that endoscopic procedures may be a promising alternative to microsurgical operations or shunting for the treatment of arachnoid cysts. Received: 30 December 1998     

症状性颅内蛛网膜囊肿的临床治疗分析

目的 探讨症状性颅内蛛网膜囊肿(IAC)的手术治疗方法、适应证及其治疗效果.方法 回顾性分析南通大学附属医院神经外科自2000年1月至2010年1月收治的32例IAC患者临床资料,总结其手术方法及疗效. 结果 本组2例保守治疗的患者失随访.随访结束时,23例(72％)患者症状明显改善(囊肿体积缩小或临床症状缓解),6例(18％)患者症状无改变(临床症状和囊肿大小无改变),1例(3.1％)巨大鞍区-鞍上区IAC患者症状加重(临床症状恶化或囊肿增大);术后影像学检查显示囊肿消失4例(12.5％),囊肿缩小16例(50％),囊肿大小无改变12例(37.5％). 结论 IAC的主要手术适应证是颅内高压、确切的神经系统损害、脑组织压迫.显微外科手术以及神经内镜是治疗IAC的有效方法.     

Resolution of the large middle fossa arachnoid cyst without any identifiable cause: Case report

Although the possibility of spontaneous regression of intracranial arachnoid cysts (AC) during observational follow-up is widely recognized, the number of reports documenting such clinical course, often associated with the mild head trauma, is rather limited. We present a case of nearly complete resolution of the large middle fossa AC in a 5-year-old boy without any identifiable cause in 2.3 years after the initial diagnosis. It once again justifies observational strategy for AC not accompanying by mass effect and manifesting with minimal symptoms or diagnosed incidentally.     

后颅凹蛛网膜的显微外科解剖学研究

目的根据头颅解剖研究结果,为后颅凹病变的显微外科手术提供解剖学依据。方法采用显微外科技术解剖和观察后颅凹蛛网膜解剖结构。结果后颅凹蛛网膜包括Liliequist膜、基底动脉分叉蛛网膜、后穿蛛网膜、动眼神经外侧蛛网膜、中脑-脑桥内侧蛛网膜、中脑-脑桥外侧蛛网膜、基底蛛网膜、脑桥腹侧蛛网膜、脑桥-延髓内侧蛛网膜、脑桥-延髓外侧蛛网膜、小脑-脑桥蛛网膜、小脑-延髓腹侧蛛网膜、小脑上蛛网膜、小脑前中央蛛网膜、小脑-延髓背侧蛛网膜、小脑后下动脉蛛网膜和小脑蚓部背侧蛛网膜,这些结构均与脑干、颅神经及血管关系密切。结论(1)后颅凹蛛网膜可分为颅底蛛网膜、凸面蛛网膜和小梁蛛网膜;(2)颅神经蛛网膜鞘为手术中分离、保护颅神经提供了可靠的解剖界面;(3)对蛛网膜及其小梁必须采取锐性分离。     

Development of a middle fossa arachnoid cyst A theory on its pathogenesis

The progression of congenital arachnoid cysts has seldom been documented. We report the case of a child who was diagnosed with arrested hydrocephalus at the age of 13 months. Neuroimaging studies performed when the girl was 22 months old showed the appearance of an arachnoid cyst in the right middle fossa, while the previously enlarged ventricles seemed to have decreased in size. To the best of our knowledge, the paradoxical expansion of an arachnoid pouch following a reduction in the size of the ventricular system has not previously been documented. We advance the hypothesis that the development of some cases of arachnoid cyst might be pathogenically related to impaired CSF dynamics associated with pre-existing hydrocephalus. We also briefly review the pertinent literature on the formation and evolution of congenital cerebral arachnoid cysts. Received: 4 September 1998     

Effective shunt-independent treatment for primary middle fossa arachnoid cyst

The results of a prospective study on excision of the outer and inner membrane for symptomatic primary middle fossa arachnoid cysts in children are presented. During the period 1982–1989, among 48 cases of cyst in various locations, 18 symptomatic patients were treated by excision of both the outer and inner membranes with an opening to the basal cistern. The mean patient age was 3.2 years. All patients were evaluated by examinations, including magnetic resonance imaging (MRI), X-ray computed tomography (CT), quantitative CT cisternography (CTC), digital substraction angiography (DSA), N-isopropyl-p[123]iodoamphetamine single-photon emission CT (IMP-SPECT) and IQ. All showed abnormal cerebrospinal fluid flow dynamics. Significant complications included massive subdural effusion in two patients and transient pulmonary edema in one. There were no recurrences during the follow-up period (mean 4.7 years). Two morphological types were noted: type I, the classical anteromedial type where the cysts are attached directly to the adjacent parasellar cisterns, and type II, the anterolateral type, where the diagonally concave anterior temporal lobe covers the adjacent cisterns, making wide opening difficult. Type I accounted for 78% of all cases, and the reduction of the cyst volume with clinical improvement was remarkable within 6 months after surgery. Angiographically, 22% of cases showed tapering and retrograde filling of the superficial middle cerebral vein. This pattern is not included in Hacker's normal variations [18] and suggest mild but chronic compression of the developing brain. Even in patients with hemispheric cyst, the reconstituted brain showed sufficient cerebral perfusion on SPECT, suggesting that the nature of this disease entity is reversible developmental arrest. These results confirm that excision is a safe, effective shunt-independent procedure for middle-fossa arachnoid cysts, especially for those of type I.     

小儿后颅窝囊肿特点和治疗探讨

目的探讨小儿后颅窝囊肿的临床特点、手术方式及疗效。方法回顾分析近10年内治疗的38例后颅窝囊肿病变患儿的临床资料。这38例患儿中行单纯囊肿一腹腔分流治疗13例,囊肿剥离开窗治疗14例（其中显微镜下剥离13例,内镜下剥离1例）,神经内镜辅助下第三脑室底造瘘术结合分流术或囊肿剥离开窗治疗（联合手术组）11例（均为巨大囊肿合并脑积水者）。结果分流组再次手术率15．4％（2113）,囊肿剥离开窗组再次手术率7．1％（1／14）,联合手术组再手术率18．2％（2111）。术后平均随访3年以上,所有病人的囊肿均缩小。结论对小儿后颅窝囊肿治疗应根据囊肿部位、大小和脑脊液吸收功能情况制定以显微镜下囊肿剥离术为首选,配合内镜和分流术的个体化手术方案。     

Postinflammatory arachnoid cyst of the quadrigeminal cistern

Arachnoid cysts of the quadrigeminal cistern are rare. Patients with this lesion are usually normal at birth, and signs of increased intracranial pressure (IICP) develop at about 4 to 12 months of age. However, there has been no report about this mechanism. A case of arachnoid cyst of the quadrigeminal cistern is presented. In this case, the process of the cyst growth was observed during the course of follow-up for shunted hydrocephalus. Symptoms coincided with the growth of the cyst. Therefore, the development of the clinical symptoms was thought to be due to IICP caused by cyst expansion. Our case was complicated by inflammation, something that may offer a key to solving the mechanism of cyst fluid accumulation and the relationship between symptoms and development of the cyst.     

颅中窝蛛网膜囊肿的外科治疗

目的 探讨颅中窝蛛网膜囊肿的临床特征、手术方法的选择。方法 分析１９８９．１￣１９９８．１本院外科治疗的２９例颅中窝蛛网膜囊肿。左侧２０例,右侧９例;男２１例,女８例。２５例行开颅蛛网膜囊肿作术,４例行囊肿－－腹腔分流术。结果 无手术死亡,随访２３例,平均时间４．１年,１８例症状消失,３例好转,２例无变化。结论 有临床症状或影像中位效应应积极手术,局限地颅中窝的中型蛛网膜囊肿宜行囊肿切除术,扩张     

Use of a ventriculosubgaleal shunt in the management of hydrocephalus in children with posterior fossa tumors

We present our experience with the use of ventriculosubgaleal shunting (VSGS) for the management of hydrocephalus associated with posterior fossa tumors in a consecutive series of 63 children. In 42 children, a temporary VSGS was inserted. There were no complications associated with the procedure, and it gave a period of several days in which to improve the general condition of the child, and to perform the necessary imaging studies, without an encumbering external drainage device. In most cases the VSGS could be removed after the posterior fossa surgery, without new general anesthesia. Other advantages and drawbacks of this technique are discussed.     

Posttraumatic intradiploic arachnoid cyst of the posterior fossa

We report the case of a 5-year-old girl with an enlarging suboccipital mass, a posttraumatic intraosseous arachnoid cyst. Diagnostic work-up revealed that the lesion consisted of an intradiploic arachnoid cyst and an extra-axial occipital pouch that communicated by way of an osseous and dural defect. Surgical repair was undertaken with good results. A search of the current literature has shown only seven previous reports of leptomeningeal cysts situated at the occipital bones, most of them the result of an antecedent skull fracture. A pathogenetic hypothesis is presented comparing the growth of arachnoid intraosseous cysts and the development of meningocencephaloceles. Received: 1 October 1996     

A case of intraventricular arachnoid cyst

A rare case of arachnoid cyst in the trigone of a lateral ventricle is reported. The patient was an 8-year-old boy who had had four episodes of convulsions prior to admission. Computed tomography (CT) and magnetic resonance imaging (MRI) demonstrated a cystic lesion containing fluid resembling cerebrospinal fluid. Although he received a cyst-peritoneal shunt, the lesion did not decrease in size. Direct removal of the cyst was then scheduled. The entirc cyst was finally removed, although it was firmly attached to the choroid plexus. The enlarged trigone gradually decreased in postoperative CT. The effectiveness of a cyst-peritoneal shunt is not always satisfactory. We recommend total resection of the cyst without use of a shunt system.     

Posterior fossa cysts: clinical,neuroradiological and surgical features

Various types of neuroimaging investigations were performed in 26 patients with posterior fossa cysts. The results were retrospectively analyzed to facilitate differential diagnosis and clarify indications for surgery. Four major findings were obtained in this study. First, posterior fossa intra-arachnoid cysts were encountered more frequently than expected and were found to be surgically treatable. Second, although IV ventricular cysts were categorized as Dandy-Walker malformation, Dandy-Walker variant, and persistent Blake's pouch in this study, the distinctions of neuroimaging findings between these three types are uncertain. Third, the diagnostic criteria for mega cisterna magna were established, and it was found be be a surgically untreatable condition. Finally, in cases with the following neuroimaging findings, surgery appears to be indicated: (1) occipital bossing or petrosal scalloping with distortion or obliteration of cerebrospinal fluid (CSF) cisterns of the posterior fossa; (2) compression and deformity of the brain surrounding the cyst; (3) radioisotope and/or computed tomography cisternographic findings suggestive of disturbance of intracystic CSF circulation; (4) a non-communicating cyst.     

儿童蛛网膜囊肿伴癫癎的外科治疗(附13例报告)

目的 探讨儿童颅内蛛网膜囊肿（ａｒａｃｈｎｏｉｄ ｃｙｓｔ,ＡＣ）与癫癎的关系以及外科治疗方法。方法 手术治疗颅内蛛网膜囊肿伴癫癎的儿童１３例,其中额叶２例,顶叶１例,颞叶８例,枕叶２例,囊肿直径在３ｃｍ以下３例,３～６ｃｍ ９例,６ｃｍ以上１例,均采用颅内蛛网膜囊肿加致癎灶切除。结果 １３例病人中,完全不发作有４例,显著改善有７例,无变化２例。结论 儿童颅内蛛网膜囊肿伴癫癎具有脑皮质结构性异常,采用颅内蛛网膜囊肿加致癎灶切除效果较为理想。