Infratentorial arachnoid cysts

The infratentorial compartment represents the second most common location of arachnoid malformations. Ten arachnoid cysts of the posterior fossa, operated on between 1970 and 1983, are reviewed. These lesions, although congenital and developmental in nature, may present at any age, and males are more frequently affected. A high rate of birth-related trauma (50% in this series) is conceivably due to fetal macrocranium, and the enlarged head and psychomotor retardation prevail in infancy and childhood. In arachnoid cysts occurring during adulthood, symptoms and signs more clearly indicate a dysfunction of the posterior fossa. Besides computerized tomography, pneumoencephalography and metrizamide techniques are recommended to rule out a Dandy-Walker syndrome in doubtful cases, and to obtain information about the cerebrospinal fluid (CSF) circulation. It is particularly important to establish the presence and type of communication of cysts with the CSF pathways. Although infratentorial cysts often communicate, they can be space-occupying masses because of increasing CSF retention, which may be due to a ball-valve mechanism or to inadequate communication. The frequently associated hydrocephalus (seven of the 10 cases in this series had hydrocephalus) seemed to be dependent mainly upon mechanical factors. The authors discuss the indications for intracranial surgery versus shunting procedures and report the results achieved by direct cyst excision.     

Arachnoid cysts of the posterior fossa

A series of 6 patients with arachnoid cysts of the posterior fossa who were treated surgically is presented. The diagnosis of the nature of the lesion and of the exact location within the posterior fossa could not be established on a clinical basis. CT scanning is the best method for diagnosing the lesion and for observing the postoperative evolution. Treatment consisted of removing the cyst walls, shunting the cyst to the peritoneum, or both. The differential diagnosis of arachnoid cysts of the posterior fossa from other cerebrospinal fluid collections, such as the megacisterna magna or the Dandy-Walker malformation, are discussed.     

Results of surgical treatment in patients with arachnoid cysts

Summary A retrospective study of 35 patients operated upon for arachnoid cysts during the last 10 years was carried out. In 19 patients treated by craniotomy, membrane resection and drainage into the basal cisterns, clinical improvement could be noted in 13 cases. Correspondingly on the CT-controls the cysts were found to have disappeared in two cases and were reduced in size in seven patients.In 11 patients, however, who were initially treated by a shunting procedure, seven patients became free of symptoms. Postoperative CT-controls showed in three cases a significant reduction of the size of the cyst, which remained unchanged in two other cases.In five patients with the combination of a nonspace-occupying arachnoid cyst and subdural effusions, drainage of the latter only was sufficient to relieve the clinical symptoms.The prominent Endings were the high complication rate of the primary or secondary shunting procedures (48%), as well as the close correlation between the clinical outcome and the postoperative CT-controls.     

The Dandy-Walker syndrome: diagnostic and surgical considerations.

Thirteen cases of the Dandy-Walker syndrome were seen over a period of 12 years. In this study their preoperative evaluation, surgical treatment and outcome is reviewed. The incidence of hydrocephalus in the series was 77%. Eight of the patients had associated central nervous system anomalies, and the need to identify these abnormalities is stressed. Because the two conditions require different surgical management, during the diagnostic work-up it is crucial to differentiate between the Dandy-Walker syndrome and extra axial cerebrospinal fluid (CSF) filled cysts, and to establish the patency of the aqueduct. The reliability of different diagnostic methods is discussed and the value of metrizamide computed tomographic ventriculography is emphasized. Unsatisfactory results following membrane excision in early cases, and observations of CSF dynamic disturbances confirm the futility of the direct approach for the management of the Dandy-Walker syndrome. The aqueduct was invariably patent and allowed either primary cyst or ventricular shunting, although simultaneous double shunting using a 'Y' connector may need to be carried out later. The mortality rate for the series was 18%. At follow-up 54.5% of the children were judged to have normal IQs.     

Developmental CSF cysts of the posterior fossa

Summary 20 cases of operated developmental CSF cysts are surveyed: 8 Dandy-Walker syndromes and 12 extraaxial arachnoid cysts. A CSF shunt is the only possible operation for Dandy-Walker syndrome and a single shunt from the cyst is preferable to a double shunt; the success rate is 50%. Congenital extraaxial arachnoid cysts, which arise from a developmental anomaly of the roof of the hindbrain or primitive leptomeningeal spaces, must be differentiated from acquired arachnoid cysts. Those of this series fall into two groups: midline and lateral. Supravermian midline cysts resemble the Dandy-Walker syndrome in several respects, including the frequent recourse to a shunt operation and the uncertain distant prognosis, whilst the other extra-axial cysts usually simulate a cerebellar tumor. Lateral cysts may, however, present peculiar symptoms such as a homolateral motor deficit that does not always respond to surgery, and an oscillating symptomcomplex. Surgical removal is the treatment of choice both for subvermian midline and lateral cysts but subsequent shunting may be necessary to control persisting hydrocephalus. The long term prognosis is generally excellent for subvermian midline cysts but may be only fair for lateral cysts.     

Stereotactic cyst/ventricular-peritoneal shunting for the treatment of prepontine arachnoid cyst: case report

BACKGROUND: Prepontine (suprasellar) arachnoid cysts are uncommon in clinical practice, so experiences in their management are limited and the best method of treatment for them remains unclear. Here we report our experience in using stereotactic cyst/ventricular-peritoneal shunting for the treatment of prepontine arachnoid cyst. CASE DESCRIPTION: A 42-year-old woman with prepontine arachnoid cyst was treated with cyst/ventricular-peritoneal shunting: the ventricular catheter was precisely inserted at a point where it could drain from the cyst and the ventricle at the same time. The postoperation CT scan showed that the cyst and the enlarged ventricle shrunk markedly. During a 1-year follow-up period, she remained symptom-free and had returned to full-time work. CONCLUSION: Stereotactic cyst/ventricular-peritoneal shunting appears to be an effective method for treating prepontine arachnoid cyst.     

Surgical therapy of symptomatic arachnoid cysts – an outcome analysis

Summary. Background. Arachnoid cysts may present with various symptoms and in different locations. Optimal treatment is still controversial, although cyst fenestration or shunt insertion are recognized as standard procedures. In this retrospective analysis the authors sought to determine which factors influence the outcome after surgery of symptomatic arachnoid cysts.Methods. 37 patients (24 male, 13 female, mean age 40.2 years) were treated within a ten year period in our institution. Mean follow-up was 39 months; follow-up was done on an ambulatory basis. For analysis patient charts were reviewed and cranial CT scans or MR investigations were examined to determine pre- and postoperative cyst volumes. Clinical outcome was graded into four subgroups using a scale based on the patients self-rating of success. Different factors were studied concerning their influence on outcome.Findings. Fenestration was performed in 28 cases, cysto-peritoneal or cysto-atrial shunting in 9 cases. A favourable outcome (subgroups 3 and 4) was achieved in 19 of 28 patients (fenestration) and in 6 of 9 patients (shunting), respectively. Mean reduction of the cyst volumes was 58% after fenestration and 74% after shunting revealing both methods to be effective. Degree of cyst volume reduction correlated significantly with clinical outcome. Patients with infratentorial cysts had more often a favourable outcome. Headache as the only symptom did not influence outcome.Conclusions. Surgery of symptomatic arachnoid cysts resulted in favourable outcome in two thirds of the patients. Both standard procedures, fenestration and shunting, are equally effective for treatment. Factors that influence outcome are the rate of volume reduction and cyst location.     

骶管内蛛网膜囊肿的MRI表现及诊断价值

目的 探讨骶管内蛛网膜囊肿的MRI特点及其诊断价值.方法 28例骶管内蛛网膜囊肿经手术病理证实.其中其中男19例,女9例,年龄16～70岁,平均41.6岁.所有病例均行MR检查.结果 囊肿位于骶管内,呈卵圆形、不规则形、串珠形.囊肿境界清楚,囊壁薄,囊液信号与脑脊液信号相似,T1WI囊液呈低信号,T2WI囊液呈高信号,其中4例囊肿内可见细条状神经根影,6例增强扫描囊液、囊壁无强化.结论 MRI是最好的影像学诊断方法;骶管内蛛网膜囊肿的发生,主要是先天的硬膜缺陷所致.     

Intracranial arachnoid cysts in children

The clinical and radiographic findings, surgical treatment, and outcome in 16 pediatric patients with intracranial arachnoid cysts are reviewed. The clinical presentation reflected the anatomical location of the lesions. Computerized tomography or magnetic resonance imaging scans were diagnostic in all cases. Of the nine cysts treated primarily or secondarily by craniotomy for fenestration and drainage into the basilar cisterns, five recurred. Cyst-peritoneal shunting led to diminished cyst size and clinical improvement in all seven cases in which it was used as the initial treatment and in all four cases in which fenestration had been unsuccessful. The results in this series show that cyst-peritoneal shunting is the treatment of choice for most intracranial arachnoid cysts in children.     

Treatment of supratentorial primary arachnoid cysts

Summary Twenty-four cases of supratentorial primary arachnoid cysts operated with different techniques are reviewed: both cyst shunting or extirpation may lead to a good early clinical result, but the former is less dangerous and more indicated in a particular group of patients; late results are better in the shunted patients. CT scan is almost always diagnostic and is mandatory postoperatively to assess the late results.     

Symptomatic secondary spinal arachnoid cysts: a systematic review

BACKGROUND CONTEXTSecondary spinal arachnoid cysts have rarely been reported but present significant challenges for management. These cysts could be anteriorly located with long rostral–caudal extensions and many are related to arachnoiditis, leading to difficult-to-treat disorders. Thus far, due to the scarcity of reports, the features of the disease and the optimal therapeutic strategies remain unclear.PURPOSETo investigate clinical features and the optimal treatment modalities of secondary spinal arachnoid cysts compared with primary spinal arachnoid cysts.STUDY DESIGNSystematic review.PATIENT SAMPLESystematic review identified 103 secondary cases from 80 studies and reports.OUTCOME MEASURESCondition of symptom relief and duration of treatment response were analyzed.METHODSAn electronic literature search of the PubMed database was conducted for studies on secondary spinal arachnoid cysts between 1990 and 2022. Non-English publications, nonhuman studies, reports of a primary cyst, studies not including case details, and studies of nonsymptomatic cases were excluded.RESULTSThis systematic review included 103 secondary cases. The most commonly reported etiologies were iatrogenic factors, trauma, and subarachnoid hemorrhage, accounting for 88 intradural extramedullary, 11 extradural, one intradural/extradural, one interdural, and one intramedullary spinal arachnoid cyst after a median duration of 30, 12, and 9 months, respectively. Extradural cysts were more prone to occur at dorsal locations and affect thoracic segments (mean cyst length: 3.4 segments). Intradural cysts showed a relatively higher ventral/dorsal ratio (1:1.09, 1.75:1, and 3.50:1 for cysts occurring from iatrogenic factors, trauma, and subarachnoid hemorrhage, respectively) and thoracic distribution, with a mean cyst length of 4.3 segments (5.1 for ventral and 3.5 for dorsal cysts). For intradural cysts, recurrence risk was lower after surgical resection than after fenestration/marsupialization (12-month recurrence risk: 21.43% vs 50.72%, log-rank test: p=.0248, Gehan–Breslow–Wilcoxon test: p=.0126). In cases treated with shunting, one recurrence (1/8 cases) was noted after external shunting and two recurrences (2/5 cases) after internal shunting at a median follow up of 12 months.CONCLUSIONSSecondary spinal arachnoid cysts, particularly intradural cysts, are rarer and more challenging to treat than primary spinal cysts. Although fenestration/marsupialization is the commonly adopted treatment, the recurrence rate is high. For unresectable cysts, shunting procedures, particularly shunting into a body cavity (eg, pleural or peritoneal cavity) away from the subarachnoid space, could be a therapeutic alternative besides fenestration/marupialization, yet its efficacy requires confirmation by more data.     

Acute intracranial hypertension and shunt dependency following treatment of intracranial arachnoid cyst in a child: a case report and review of the literature

Arachnoid cysts are developmental anomalies that represent 1% of all intracranial space occupying lesions. Treatment of symptomatic cases may include shunting of the cyst or an open fenestration of it, among other less acceptable surgical procedures. Each procedure has its own pros and cons. We present a case of the development of an acute intracranial hypertension during cysto-peritoneal shunt malfunction in a child. We describe the possible mechanism of these phenomena and, based on this report and by reviewing other case series in the literature, we raise the possibility that acute increase in intracranial pressure and the development of shunt dependency, although rare, are important complications of shunting an arachnoid cyst.     

Treatment of symptomatic intracranial arachnoid cysts by stereotactic cyst-ventricular shunting

BACKGROUND: The optimal treatment of symptomatic intracranial arachnoid cysts is controversial and different surgical approaches have been described. The aim of the treatment is to reduce the intracystic pressure. To accomplish this goal, many techniques have been proposed, each with specific limitations or failures. METHODS: Nine patients with symptomatic arachnoid cysts were treated by stereotactic cyst-ventricular shunting. One patient with suprasellar arachnoid cyst showed signs related to intracranial pressure, the remaining 8 patients complained of headache and/or drug-resistant epilepsy. All the intracranial cysts were supratentorial. The surgical procedure was performed under general anesthesia in 6 cases and local anesthesia in 3 cases. The CRW Stereotactic System (Radionics) was used. The acquisition of both target points (cyst and ventricle) was always realized by means of CT scan slices. A right precoronal burr hole was made and a silicon catheter was stereotactically inserted into the lateral ventricle. Another burr hole was subsequently performed close to the cyst; a silicon catheter was placed in the middle of the cavity in the shortest intracerebral crossing. Then both catheters were connected to a subcutaneous burr hole Ommaya reservoir. RESULTS: All patients tolerated the procedure well and the preoperative clinical signs progressively disappeared or improved. The CT scan at 1, 3, 6 and over 12 months showed progressive reduction in size of the cysts. No clinical recurrence was found at the follow-up (14-73 months). CONCLUSIONS: The successful outcome of the above cases suggests that, in carefully selected symptomatic intracranial arachnoid cysts, stereotactic cyst-ventricular shunting is likely to prove an effective operative method.     

Suprasellar arachnoid cysts: Options in operative management

Summary Suprasellar arachnoid cysts are uncommon lesions the optimal management of which is still subject for debate. Various authors have presented differing treatment preferences which include: 1) Subfrontal fenestration of the cyst to the basal cisterns; 2) Transcallosal fenestration of the cyst into the lateral ventricles with optional shunting; 3) Cystoperitoneal shunt; 4) Percutaneous ventriculocystostomy. There is a significant incidence of re-operation whatever the initial approach.Based on recent experience with 5 operative cases of suprasellar arachnoid cyst and a selective review of 6 major operative series covering 42 cases, the available surgical options are critically analyzed. Percutaneous ventriculostomy may offer the best chance for a definitive treatment. However the technique is demanding and is not readily available. Cystoperitoneal shunting entails shunt dependency and has a significant incidence of failure, as does cyst marsupialization to the subarachnoid cisterns. The establishment of a single CSF space by surgically communicating the cyst with the ventricular system appears to offer the best chance of success in the treatment of suprasellar arachnoid cysts, though a concomittant shunt may still be required in the occasional hydrocephalic patient.     

Spontaneous Disappearance of Temporo-Frontal Arachnoid Cyst in a Child

Summary  We report a child with a large temporo-frontal arachnoid cyst which resolved spontaneously. There was no history of a head injury. The patient was a boy aged 1.6 years. Though a large head was pointed out (+2SD), no therapeutic intervention was made because the relationship of the head circumference and the cyst was not established. No change in cyst size was visualized on the follow-up CTs at the age of 2.5 years and 6 years. At the age of 7 years, the arachnoid cyst had completely disappeared on CT. In order not to overlook a minute change in cyst size, the volumetry of the cyst and the intracranial cavity was performed, using the Photoshop, Macintosh. Both the cyst volume and the volume ratio of the cyst to the intracranial cavity slightly decreased and then increased. It is speculated that the cyst spontaneously ruptured by factors such as extreme breath holding and crying on the presence of the higher intracystic tension which might become a factor to accelerate spontaneous rupture of the cyst. Since a number of paediatric cases of symptomatic arachnoid cysts in need of surgical intervention has been larger than that of adult cases, we can speculate that a large arachnoid cyst might spontaneously resolve more frequently than we had expected. This case demonstrates that the surgical treatment of asymptomatic arachnoid cyst in the middle cranial fossa is not necessarily indicated in children.     

骶管内蛛网膜囊肿的外科治疗

目的探讨骶管内蛛网膜囊肿的诊断及治疗方法。方法23例骶管内蛛网膜囊肿患者行椎板减压术后,分别对囊肿进行处理。13例行囊肿大部切除后,重新缝合残余部分以包绕囊内神经根;8例囊肿大部切除后用肌肉填塞交通孔;2例囊肿切开旷置。随访时间3个月～11年2个月,平均30.2个月,观察疗效,并对其临床表现,术中的病理特点,术后并发症,以及X线片、CT、CTM、MRI等影像学资料进行分析。结果MRI可清晰地显示囊肿呈长T1及T2信号,信号强度与脑脊液一致。临床症状以骶管内神经受压表现为主,囊肿与硬膜囊一般有交通孔。囊肿切除后重新缝合包绕神经组与囊肿切除肌肉填塞组优良率并无统计学差异。术后并发症有皮肤糜烂和颅内感染。结论骶管内蛛网膜囊肿的发生是由于先天性硬脊膜缺陷所致。对囊肿的处理以囊肿切除、肌肉填塞封堵交通孔最为合理。术后以不放引流条及忌平卧为宜。     

Spinal hydatid cyst mimicking arachnoid cyst on magnetic resonance imaging

BACKGROUND: Primary spinal hydatid cysts are uncommon and account for 1% of all cases of hydatid disease. Echinococcus granulosus is most often responsible for the cyst hydatid. Intradural, extramedullary involvement is rare. When the cysts do not demonstrate typical magnetic resonance imaging findings, the differential diagnosis is more complex. METHOD: Case report. FINDINGS: An isolated primary hydatid cyst of the spine in a 35-year-old man that appeared to be an arachnoid cyst on preoperative radiographic examination. CONCLUSION: Hydatid cysts that lack the typical radiographic appearance may be mistaken for arachnoid cysts. Misdiagnosis has serious implications for surgical intervention and long-term care.     

Non-traumatic intradiploic arachnoid cyst

Summary In this report, we present a case of non-traumatic intradiploic arachnoid cyst in a 65 year-old woman with a slow growing swelling in the right frontotemporal region without a history of head trauma, which was diagnosed intra-operatively. Extradural intracranial location of non-traumatic arachnoid cyst is a rare clinical entity with a few reported cases in the literature. Characteristic features of non-traumatic intradiploic arachnoid cysts are also described in this mini-review article.     

症状性骶管内囊肿的诊断与治疗

目的：探讨症状性骶管内蛛网膜囊肿的诊断与治疗方法.方法：对12例以骶管内神经受压表现为主,如腰骶部疼痛、下肢痛、会阴部疼痛,鞍区麻木不适,大小便障碍,下肢无力患者,行MRI检查.结合临床症状、体征及MRI表现明确诊断为症状性骶管内囊肿后行手术治疗.手术均在显微镜下操作.对未见明显交通孔的7例中5例行囊壁大部切除后残存囊壁修补缝扎,2例因硬脊膜缺如,无法修补而行囊肿部分切除旷置;5例有交通孔的患者中,2例囊肿大部切除后用肌肉填塞交通孔,2例因交通孔处理困难未作特殊处理,1例囊肿大部切除后,切开交通孔处硬脊膜以扩大交通孔至脑脊液通畅流出,消除交通孔的单向阀门作用.严密缝合切口,术后采取头低臀高俯卧位.结果：骶管内囊肿在MRI上表现为骶管内单发或多发类圆形或椭圆形的软组织影,呈长T1、长T2表现,信号与脑脊液相同.术后2例出现少量皮下积液,加压包扎2～3个月后自行吸收,无1例脑脊液漏.随访3个月～4年6个月,平均18.3个月,症状完全缓解8例,部分缓解3例,1例3个月后症状复发,MRI检查示囊肿较术前轻微扩大,未再次手术.结论：MRI检查是正确诊断骶管内蛛网膜囊肿的有力手段,伴有临床症状、体征者应考虑手术治疗.对囊肿的处理以囊肿大部切除为主,严密缝合切口各层及术后合理体位可以有效防止并发症的发生.     

Posterior fossa arachnoid cysts.

Arachnoid cysts of the posterior fossa are rare lesions that are considered to be mostly congenital in origin. In this article, we retrospectively review 12 patients who underwent surgical treatment for their symptomatic posterior fossa arachnoid cysts. The most common presenting symptoms were gait disturbances and headache. The diagnosis was established on computed tomography or magnetic resonance imaging. Surgery consisted of cyst wall excision with fenestration in nine cases and shunting procedures in three cases. In all cases except one who-died, the postsurgical follow-up neuroradiological investigations showed that the cysts had decreased in size, the cerebellum had re-expanded, and if there was preoperative hydrocephalus, the ventricular size was decreased. The follow-up period ranged from 1 to 11 years. All surviving cases are free of symptoms and no arachnoid cysts recurred. The classification, pathophysiology, differential diagnosis and surgical treatment of infratentorial arachnoid cysts are discussed and the relevant literature is reviewed.