Symptomatic Arachnoid Cysts Research Articles

Suprasellar arachnoid cyst after subdural haemorrhage in an infant. A case based update

IntroductionBrain arachnoid cysts (AC) are congenital or acquired malformations. Their prevalence in children ranges between 0.2 and 2.3% of the studied populations. Few reported studies exist where AC appears after a subdural haemorrhage. MethodsWe present one case of a symptomatic suprasellar AC after post-traumatic subdural haemorrhage in an infant. ResultsAfter endoscopic ventriculocystostomy, the child quickly improved and the cyst reduced in size. The child was monitored for 22 months and his neurocognitive development remained normal. ConclusionOur case led us to the hypothesis that the inflammatory process due to subdural haemorrhage may locally result in arachnoiditis, and thus to the creation of a neomembrane, and eventually to cyst formation. This is also the case with the development of post-traumatic spinal AC.

Galvos smegenų arachnoidinių cistų endoskopinis gydymas

Arachnoid cyst is a congenital collection of fluid similar like cerebrospinal fluid between the leaves of arachnoid. Usually they have no connections with subarachnoid space. Symptomatic arachnoid cysts are treated surgically. The method of surgical treatment depends according to the cyst location, surgeons experience and available instruments. The methods of arachnoid cysts surgical treatment are: craniotomy and open cyst extirpation and connection with subarachnoid space, endoscopic cyst aspiration and connection with subarachnoid space (cystocysternostomy) or ventricles (cystoventriculostomy) and cystoperitoneal shunting. We describe the method of endoscopic treatment of arachnoid cysts and review the clinic, diagnostic and early results of patients treated at the Department of Neurosurgery, Klaipėda University Hospital. There were 6 patients who underwent endoscopic surgery for arachnoid cysts during the period from January 2011 till January 2013. Four patients (66.7 proc.) had arachnoid cysts of middle cranial fossa and two (33.3 proc.) had intraventricular arachnoid cysts. Four patients underwent endoscopic cystocysternostomy and two patients underwent endoscopic cystoventriculostomy and cystoventriculocysternostomy. We observed early improvement in all patients. Diabetes insipidus has developed to one patient as a complication of surgery. Conclusion. Endoscopic surgery for arachnoid cysts is an effective, safe and minimally invasive treatment method. It must be the first method of surgery for most symptomatic arachnoid cyst. doi:10.5200/sm-hs.2013.071

Risk Factors for Pediatric Arachnoid Cyst Rupture/Hemorrhage

As the availability of imaging modalities has increased, the finding of arachnoid cysts has become common. Accurate patient counseling regarding physical activity or risk factors for cyst rupture or hemorrhage has been hampered by the lack of definitive association studies. This case-control study evaluated factors that are associated with arachnoid cyst rupture (intracystic hemorrhage, adjacent subdural hematoma, or adjacent subdural hygroma) in pediatric patients with previously asymptomatic arachnoid cysts. Patients with arachnoid cysts and intracystic hemorrhage, adjacent subdural hygroma, or adjacent subdural hematoma treated at a single institution from 2005 to 2010 were retrospectively identified. Two unruptured/nonhemorrhagic controls were matched to each case based on patient age, sex, anatomical cyst location, and side. Risk factors evaluated included arachnoid cyst size, recent history of head trauma, and altitude at residence. The proportion of imaged arachnoid cysts that presented either originally or subsequently with a rupture or hemorrhage was 6.0%. Larger cyst size, as defined by maximal cyst diameter, was significantly associated with cyst rupture/hemorrhage (P < .001). When dichotomized with a 5-cm cutoff, 9/13 larger cysts ruptured and/or hemorrhaged, whereas only 5/29 smaller cysts ruptured/hemorrhaged (odds ratio = 16.5 (confidence interval [2.5, ∞]). A recent history of head trauma was also significantly associated with the outcome (P < .001; odds ratio = 25.1 (confidence interval [4.0, ∞]). Altitude was not associated with arachnoid cyst rupture or hemorrhage. This case-control study suggests that larger arachnoid cyst size and recent head trauma are risk factors for symptomatic arachnoid cyst rupture/hemorrhage.

Analysis about the result of cystoperitoneal shunt for the treatment of arachnoid cysts in children

Objective To evaluate the clinical significance of cystoperitoneal shunt in surgical management of intracranial arachnoid cyst.Methods Between January 2003 and January 2005,62patients with arachnoid cysts underwent cystoperitoneal shunt in our institute.All patients were evaluated with CT or MRI and had regular follow-up examinations.Results 46 patients were (74％) cysts within the sylvian fissure,8 patients (13％) were in the cerebral convexity,8 patients (13％) were infratentorial.Cystoperitoneal shunt was placed in all patients; Follow-up imaging studies showed that the size of arachnoid cysts was reduced in 59 patients (95％) during a mean postoperative follow-up period of 6.5years (range,6 to 8 years).Although a cystoperitoneal shunt was the effective method for early achieving obliteration,there were 16 shunt-related complications,including 8 patients suffered from typical symptom of pseudotumor cerebri with a shunt malfunction suggesting shunt dependency.Conclusions Shunt placement is a safe and effective surgical treatment of symptomatic arachnoid cysts in children.Efforts should be made to decrease the complication of the shunt of arachnoid cysts. Key words: Arachnoid cyst; Children; Shunt

Long-term results of cystoperitoneal shunt placement for the treatment of arachnoid cysts in children

The authors present a single-institution experience in shunt treatment for arachnoid cysts (ACs). Between January 2003 and January 2005, 62 patients with ACs underwent cystoperitoneal (CP) shunt placement at the authors' institution. All patients were evaluated with CT or MRI studies and had regular follow-up examinations. Forty-six cysts (74%) were within the sylvian fissure, 8 (13%) were in the cerebral convexity, and 8 (13%) were infratentorial. A CP shunt was placed in all patients. Follow-up imaging studies showed that 59 (95%) of 62 ACs reduced in size during a mean postoperative follow-up period of 6.5 years (range 6-8 years). Although a CP shunt was effective in achieving early obliteration, shunt dependency occurred within the patient group (13%). Shunt revision for various reasons was performed in 16 patients (26%). Shunt placement is a safe and effective surgical treatment for symptomatic ACs in children, although efforts should be made to decrease complications in the procedure.

CT cisternography in intracranial symptomatic arachnoid cysts: Classification and treatment

ObjectivesThe symptom and neuroimaging as indications for treating arachnoid cysts (ACs) are not adequate. Understanding the communication between cyst and subarachnoid space is helpful for decision-making. We took a dynamic study of ACs using CT cisternography (CTC) and proposed a classification of arachnoid cysts. Materials and methodsTotal 52 symptomatic patients with ACs were enrolled in this prospective study. CTC images were ordered, in all enrolled patients, at the 1, 3, 6, 12, 24 and 48h after the intrathecal Omnipaque administration. Enhancement in cysts was measured quantitatively and was compared with neighboring subarachnoid spaces. All enrolled patients were allocated randomly in 2 groups. The CTC result was considered before treatment in one group (CTC group), while another group was surgically treated without considering CTC results (surgical group). ResultsACs in our study were classified into 3 types: complete (cyst filling time at 1h), incomplete (filling time began at 3h) and noncommunicating cysts (no or slight filling after 24h). Twenty-two patients in CTC group with incomplete communicating, or noncommunicating cysts underwent surgeries. And other 6 patients with complete communicating cysts were closely observed. In CTC group, the symptom of all surgical patients was relieved, and 5 out of 6 observational patients showed clinical improvement or no deterioration during the follow-up. In surgical group, only 18 out of 24 patients showed clinical improvement after surgeries, and there were 6 patients showing no difference before and after surgeries in symptom and in imaging. ConclusionsThis classification based on dynamic CT cisternography is useful for the decision of surgical indication. Some symptomatic patients with complete communicating ACs may not need surgical intervention.

Endonasal management of sellar arachnoid cysts: simple cyst obliteration technique

Symptomatic sellar arachnoid cysts (ACs) have typically been treated via the transsphenoidal route. After sellar cyst wall fenestration, some authors have advocated cyst wall resection and increasing communication between the AC and suprasellar subarachnoid space (SAS). This study is a report of the authors' experience using a simplified approach to reinforce a defective diaphragma sellae or unseen arachnoid diverticulum by deliberately not enlarging the AC-SAS communication and obliterating the cyst cavity with adipose tissue followed by skull base reconstruction. A retrospective analysis was conducted of patients who underwent an endonasal transsphenoidal obliteration of symptomatic ACs with a fat graft and skull base repair. Between July 1998 and September 2010, 8 patients with a sellar AC were identified (6 women and 2 men, mean age 57 years). Clinical presentation included headache, pituitary dysfunction, and visual dysfunction (4 patients each group). Maximal cyst diameter averaged 22 mm (range 15-32 mm). In all cases the sellar communication to the SAS was deliberately not enlarged. The endoscope was used for visualization in 8 of 9 procedures. Postoperatively, headache improved in all 4 patients, vision in all 4 patients, and partial resolution of endocrine dysfunction (hyperprolactinemia and/or recurrent hyponatremia) occurred in 3 (75%) of 4 patients. No new endocrinopathy, CSF leak, meningitis, or neurological deficits occurred. Two patients experienced cyst reaccumulation: 1 symptomatic recurrence was treated with reoperation at 43 months postsurgery, and 1 asymptomatic partial recurrence continued to be monitored at 29 months postsurgery. Sellar ACs can be effectively treated using endonasal fenestration and obliteration with fat with resultant reversal of presenting symptoms in the majority of patients. This simplified technique of AC cavity obliteration without enlarging communication to the SAS has a low risk of CSF leakage, and in most cases appears to effectively disrupt cyst progression, although longer follow-up is required to monitor for cyst recurrence.

Surgical management strategies of intracranial arachnoid cysts: a single institution experience at 75 cases

Arachnoid cysts are benign intra-arachnoid cystic lesions filled with cerebrospinal fluid. With advent of modern treatment techniques, debate continues regarding which surgical treatment is most effective. MATERIAL and A consecutive series of 75 patients with arachnoid cysts that were surgically treated between January 1992 and December 2009 are reported. Included in the study were 54 male and 21 female patients, ranging in age from 2 months to 45 years (mean age 20.02 years) at the time of surgery. Symptoms at presentation, location on the cysts, and treatment modalities were evaluated. Headache was controlled in 92.5% of adult cases. Hydrocephalus, cognitive decline weakness and gait disturbances were controlled 100% after overall treatment methods. Follow-up CT scans showed significant reduction in cyst size in supratentorial arachnoid cysts. No significant changes in cyst size were found in infratentorial cysts but symptomatic improvements were noted. Patients with symptomatic arachnoid cysts regardless of age and cyst location should be treated. We think that avoiding shunt dependence should be one of the principle treatment goals. Proper patient selection results in good outcomes.

Rapid brain shift, remote site hemorrhage, and a spinal hematoma after craniotomy for a large arachnoid cyst

Arachnoid cysts are prevalent among the general population. The management options of symptomatic arachnoid cysts each have their own merits and disadvantages. We report a case where a large arachnoid cyst was treated by open fenestration and marsupialization that was complicated by remote intraparenchymal and spinal subdural hemorrhage. The potential physiological changes underlying these complications as well as the related literature are reviewed.

CT-Guided Percutaneous Injection of Fibrin Glue for the Therapy of Symptomatic Arachnoid Cysts

Although often asymptomatic, enlarging sacral arachnoid cysts can also cause significant discomfort. These symptomatic sacral arachnoid cysts require specific treatments to facilitate local decompression. The main drawback of the surgical managements is the high risk of recurrence and complications. To decrease risks, we had been attempting to seek a simple and safe method to manage the symptomatic sacral arachnoid cysts. CT-guided percutaneous fibrin glue therapy is a new nonsurgical alternative. To evaluate the efficacy of the novel nonsurgical approach, we conducted this retrospective study of 38 patients. Thirty-eight patients with symptomatic sacral arachnoid cysts underwent fibrin glue therapy in our hospital between June 2006 and May 2009. The clinical results of improvement in pain and neurologic function were evaluated after an average of 25 months of follow-up, and changes on the imaging findings were evaluated. Preoperative and postoperative pain severity was assessed according to a 10-cm VAS. Moreover, we also analyzed the postoperative complications. Most patients experienced some degree of pain relief and functional improvement after fibrin glue therapy, with most experiencing complete or marked resolution of clinical symptoms. Twenty-one patients (55.3%) reported excellent recovery, 12 (31.5%) reported good recovery, 4 (10.5%) reported fair recovery, and 1 (2.6%) reported poor recovery. The overall percentage of positive outcomes (excellent and good recovery) was 86.8%. No serious postoperative complications were discovered. CT-guided percutaneous injection of fibrin glue therapy is simple, safe, and effective for the management of symptomatic sacral arachnoid cysts.

Lumbar intraspinal arachnoid cyst superimposed by hyperacute spinal subdural hematoma: an unusual case

Background context Lumbar intradural arachnoid cyst (AC) concomitant with hyperacute spinal subdural hematoma (SSDH) has never been reported in the literature. Purpose To report a case of lumbar AC superimposed by hyperacute SSDH, which was difficult to diagnose preoperatively using magnetic resonance imaging. Herein, we describe diagrams showing the proposed mechanisms underlying the formation of a symptomatic AC. Study design/setting The study was designed to be a case report and literature review. Methods A 65-year-old man presented with acute onset of low back pain, followed by 5-day history of numbness and weakness in both legs before admission. Magnetic resonance imaging of the lumbosacral spine revealed an intradural extramedullary biconvex lesion at the L3–L4 level; the lesion compressed the cauda equina posteriorly. The lesion mainly appeared as hyperintense on T2-weighted images and hypointense on T1-weighted images. On the basis of these findings, the lesion was preoperatively diagnosed as a symptomatic lumbar subdural AC that compressed the cauda equina. Results The patient underwent laminectomy from L2 to L4. After a dura incision, a partially organized subdural hematoma was noted. Beneath the subdural hematoma was an AC compressing the underlying nerve roots. The patient’s back pain and muscle strength markedly improved after the operation. Conclusions Preoperative diagnosis of concomitant hyperacute SSDH and AC is difficult. In cases of patients who present with intraspinal AC accompanied by an acute onset of clinical presentation, an associated etiology should be considered until proven otherwise.

Cyst-ventricle stent as primary or salvage treatment for posterior fossa arachnoid cysts

The optimal treatment of symptomatic posterior fossa arachnoid cysts is controversial. Current options include open or endoscopic resection, fenestration, or cyst-peritoneal shunt placement. There are potential drawbacks with all options. Previous authors have described stenting a cyst into the ventricular system for supratentorial lesions. The current authors have used a similar strategy for posterior fossa cysts. The authors performed a retrospective review of 79 consecutive patients (1993-2010) with surgically treated intracranial arachnoid cysts. The authors identified 3 patients who underwent placement of a stent from a posterior fossa arachnoid cyst to a supratentorial ventricle. In 2 patients the stent construct consisted of a catheter placed into a posterior fossa arachnoid cyst and connecting to a lateral ventricle catheter. Both patients underwent stent placement as a salvage procedure after failure of open surgical fenestration. In the third patient a single-catheter cyst-ventricle stent was stereotactically placed. All 3 patients improved clinically. Two patients remained asymptomatic, with radiographic stability in a follow-up period of 1 and 5 years, respectively. The third patient experienced initial symptom resolution with a demonstrable reduction of intracystic pressure. However, he developed recurrent headaches after 2 years. Posterior fossa cyst-ventricle stenting offers the benefits of ease of surgical technique and a low morbidity rate. It may also potentially reduce the incidence of shunt-related headaches by equalizing the pressure between the posterior fossa and the supratentorial compartments. While fenestration is considered the first-line therapy for most symptomatic arachnoid cysts, the authors consider cyst-ventricle stenting to be a valuable additional strategy in treating these rare and often difficult lesions.

Assessment of endoscopic treatment for middle cranial fossa arachnoid cysts

Endoscopic cystocisternotomy is one of three surgical methods used to treat middle cranial fossa arachnoid cysts. There is debate about which method is the best. The aim of this study is to evaluate the effectiveness and safety of endoscopic cystocisternotomy for treatment of arachnoid cysts of the middle cranial fossa. Thirty-two patients with arachnoid cysts of the middle cranial fossa who had undergone endoscopic cystocisternal fenestration between 2004 and 2009 were studied retrospectively. Data were obtained on clinical and neuroradiological presentation, indications to treat, surgical technique, complications, and the results of clinical and neuroradiological follow-up. Among the 27 patients with symptoms before surgery, 8 had disappearance of symptoms and 17 had improvement of symptoms. The cyst was reduced in size or it completely disappeared in 24 (75%) patients. The incidence rate of complications was 18.8%. Endoscopic cystocisternal fenestration is an effective treatment for symptomatic arachnoid cysts of the middle cranial fossa and should be the initial surgical procedure.

Shunting for the Treatment of Arachnoid Cysts in Children

The optimal treatment of symptomatic arachnoid cysts remains controversial. We present a single-institution experience on surgical treatment of arachnoid cysts. Between January 1983 and January 2008, 92 patients with symptomatic arachnoid cysts underwent surgery at our institute. All patients were evaluated with CT and/or MRI and were operated upon and had regular follow-up examinations. There were 60 males and 32 females. The mean age was 3.6 years (range, 2 days to 14 years). Forty-eight cysts (52%) were within the sylvian fissure, 16 (17%) were in the cerebral convexity, 15 (16%) were infratentorial, 10 (11%) were in the interhemispheric fissure, and 3 (4%) were parasellar. Cystoperitoneal shunt was placed in 67 (73%) patients; ventricular drainage alone was performed in 14 (15%) patients; and combined drainage of the ventricular system and cyst, using a 3-way connector, was performed in 8 (9%) patients. Craniotomy and fenestration of the cyst was performed in 2 (2%) patients, whereas total excision of the cyst was performed in 1 patient. Shunt revision for various reasons was performed in 34 patients (39%), whereas 13 (14%) patients required more than one revision. Complete alleviation of symptoms was achieved in all patients after treatment, regardless of cyst reduction. After a mean follow-up of 8.5 years no further enlargement of the arachnoid cysts was noted. Shunt placement is a safe and effective surgical treatment of symptomatic arachnoid cysts in children. Cyst reduction is greater in children younger than 2 years of age.

Endoscopic treatment of middle fossa arachnoid cysts

To investigate and evaluate the effectiveness of neuroendoscopic therapy for arachnoid cysts of middle cranial fossa. From January 2004 to June 2009, 32 patients with arachnoid cysts of middle cranial fossa who were treated with endoscopic cystocisternal fenestration were retrospectively analyzed. There were 21 male patients and 11 female patients, aged from 6 months to 39 years. The clinical and neuroradiological presentation, indications, surgical technique, complications, and clinical and neuroradiological follow-up were analyzed. The cysts were reduced in size in 20 patients and completely disappeared in 4 patients. For the 27 patients with symptoms before operation, the symptoms disappeared in 8 cases and improved in 17 cases after operation. There were asymptomatic subdural hydroma in 4 patients, intracranial infection and incision cerebro-spinal fluid leakage in 1 patient respectively. The complication incidence rate was 18.8%. Endoscopic fenestration is an effective treatment for symptomatic arachnoid cysts of middle cranial fossa and could be performed as the first surgical choice for these patients.

Endoscopic management of large multicompartmental intraventricular arachnoid cyst extending from foramen magnum to foramen of Monro

The treatment options for symptomatic arachnoid cysts are shunting, open craniotomy, and endoscopic fenestration. Endoscopic fenestration of large arachnoid cyst is safe and effective. Postoperative subdural hematoma and intraparenchymal hemorrhage can be avoided by endoscopic fenestration. This technique has the additional advantage of identifying and treating ventricular abnormalities, such as foramen of Monro stenosis and cerebral aqueduct occlusion. This report describes endoscopic dual fenestration in a child with large multicompartmental intraventricular arachnoid cyst extending from foramen magnum to foramen of Monro. The child presented with difficulty to hold the neck in upright position, irritability, vomiting, and large head. Follow-up postoperative magnetic resonance imaging at 3 months showed a significant reduction in size of the cyst. Clinically, the patient showed a gradual improvement at 10 months follow-up. Probably this is the first report of this nature.

Delayed Recurrent Arachnoid Cyst of the Occipital Convexity in an Elderly Woman -Case Report-

A 62-year-old woman presented with a symptomatic arachnoid cyst of the right occipital convexity manifesting as visual disturbances and headache. She underwent craniotomy with membranectomy and fenestration to the subarachnoid space. Postoperatively, her complaints disappeared and brain magnetic resonance (MR) imaging showed cyst shrinkage. During the first 1 year after surgery, she made a good recovery without clinical symptoms or cyst enlargement. However, she complained of visual disturbances after 6 years. Brain MR imaging revealed cyst enlargement and Goldmann perimetry detected left lower quadrantanopia. The diagnosis was recurrent arachnoid cyst. A second surgical procedure was performed including membranectomy for histological examination of the cyst membrane, and an Ommaya reservoir was inserted into the cyst cavity to prevent further cyst enlargement. The histological findings were compatible with arachnoid cyst, similar to the results seen at the first surgery. She was discharged 3 weeks after the second operation with no complications, and follow up continues as an outpatient. Patients with symptomatic arachnoid cysts typically have good progress after surgery, but the present case shows that follow up should continue for at least 6 years after surgery, even if cyst volume reduction was initially favorable.

Endoscopic management of intracranial cysts

Endoscopic fenestration has been recognized as an accepted treatment choice for patients with symptomatic arachnoid cysts. The success of this procedure, however, is greatly influenced by individual cyst anatomy and location as well as the endoscopic technique used. This review was conducted to assess what variables influence the treatment success for different categories of arachnoid cysts. Thirty-three consecutive patients who underwent endoscopic fenestration for treatment of an intracranial arachnoid cyst were identified from a prospective database. The surgical indications and techniques were reviewed, and surgical success rates and patient outcomes were assessed. Specific examples of each cyst category are included to illustrate the technical aspects of endoscopic cyst fenestration. Endoscopic fenestration of arachnoid cysts was successful when judged by cyst decompression, and symptom resolution was noted in 32 (97%) of 33 cases. The one patient with short-term treatment failure underwent a successful repetition of the operation. There were no surgery-related morbidities or deaths. Arachnoid cysts are a relatively benign pathological entity that can be managed by performing endoscopically guided cyst wall fenestrations into the ventricular system or cerebrospinal fluid-containing cisterns. Proper patient selection, preoperative planning of endoscope trajectory, use of frameless navigation, and advances in endoscope lens technology and light intensity combine to make this a safe procedure with excellent outcomes.

Tratamiento quirúrgico de los quistes aracnoideos sintomáticos en niños

When symptomatic, arachnoid cysts (AC) must be treated surgically. The best surgical technique, however, is at the present time still subject to controversy -implantation of a cyst-peritoneal shunt (CPS) or fenestration of the cyst, either by means of a craniotomy or by using endoscopic techniques. This paper reports the findings from a series of 18 patients under 10 years of age who were treated for symptomatic ACs. An increase in the cranial perimeter was observed in 12 patients, 4 had headaches and 2 children suffered convulsive crises. In 11 cases the location was supratentorial and in 7 it was found to be infratentorial. Treatment involved a cyst-peritoneal or ventriculoperitoneal shunt in 12 cases. Endoscopic treatment of the cyst was carried out in 5 of the patients and in 1 case craniotomy debridement was performed. Seven of the 18 children required a second intervention to resolve the clinical condition, either due to poor valve functioning or because the endoscopic treatment was insufficient. Complications included 2 subdural haematomas, which required surgical treatment. No mortality or morbidity occurred. The progress being accomplished in endoscopic techniques can make them the ideal form of treatment rather than craniotomy debridement techniques, although the high percentage of no-resolution in children below the age of 15 months must be taken into account. CPS solves the problem of these cysts with a lower degree of surgical risk, but it has a high rate of reintervention, as well as the dependence on the shunt. In the review of the literature we carried out it was seen that reports are still published concerning series treated by both cyst fenestration and by means of shunts.

Surgical therapy of symptomatic arachnoid cysts - an outcome analysis.

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. 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. 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. 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.