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.     

Intradural arachnoid cysts of the spinal canal associated with intramedullary cysts

Five patients had intradural arachnoid cysts of the thoracic spinal canal associated with syringomyelia or posttraumatic intramedullary spinal cord cysts. Three cases were diagnosed 6 to 18 years after spinal surgery and two 14 to 17 years after spinal cord trauma. In each case, delayed progression of symptoms led to the identification of the lesions. The diagnosis was assisted by the use of myelography and delayed computerized tomography scanning in two cases and by magnetic resonance imaging in all five. In each case, the arachnoid cyst appeared to compress the spinal cord or nerve roots; in three cases, the syrinx cavities appeared to exert a significant mass effect. In the two trauma-related cases, the intramedullary cysts were small and may have represented areas of cystic myelomalacia. In four cases, intraoperative real-time ultrasonography helped to localize the arachnoid and intramedullary cavities. All five patients were treated by fenestration of the arachnoid cyst; additional peritoneal shunting of the cyst was performed in one case and of the intramedullary cavity in three. In one patient, the two lesions appeared to have a balancing effect; after drainage of the arachnoid cyst, the syrinx cavity expanded and had to be treated separately. The neurological deficits were reduced in four patients and stabilized in one. Intradural arachnoid cysts and intramedullary cysts may occur together as a late complication of spinal surgery or spinal cord trauma, and either or both lesions may cause delayed neurological deterioration.     

Intracranial arachnoid cysts in children. A comparison of the effects of fenestration and shunting

The best operative intervention for children with arachnoid cysts remains the subject of controversy. Recent reports stress that craniotomy for cyst fenestration is associated with a low incidence of morbidity and mortality and may leave the child shunt-independent. The cases of 40 pediatric patients with arachnoid cysts treated between 1978 and 1989 are reported. Five children with mild symptoms and small cysts that remained stable on follow-up studies have not required surgical intervention. Of 15 patients with cysts initially treated by fenestration, 10 (67%) showed no clinical or radiographic improvement postoperatively and have undergone cyst-peritoneal (eight patients) or ventriculoperitoneal (VP) shunting (one patient), or revision of a VP shunt placed for hydrocephalus before cyst fenestration (one patient). Two other patients with existing VP shunts required no further procedures. Thus, only three (20%) of 15 patients initially treated by fenestration remain shunt-independent after a median follow-up period of 8 years. The 20 other patients were initially treated by cysts shunting and all improved postoperatively; shunt revision has been necessary in six (30%) of these 20 patients because of cysts recurrence. Cyst location influenced the success of shunt treatment; none of the seven middle cranial fossa cysts treated by shunting have required revision, but results with cysts in other locations were less favorable. In all locations, though, shunting was more successful than fenestration. It is concluded that cyst-peritoneal or cyst-VP shunting is the procedure of choice for arachnoid cysts in most locations, including those in the middle cranial fossa.     

Surgical therapy of symptomatic arachnoid cysts - an outcome analysis

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.     

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.     

Surgical treatment of patients with midline arachnoid cysts

Usually, arachnoid cysts are found in the Sylvian fissure (about 85%); midline arachnoid cysts are rare. Typical clinical symptoms are increased intracranial pressure, caused by a concomitant hydrocephalus, as well as visual and/or endocrinological disturbances.Six patients were examined, treated with one of two different surgical methods (cyst shunting or open treatment, either craniotomy/cyst membrane resection or laser endoscopy).Better results were observed following open treatment methods.     

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.     

Intradural spinal arachnoid cysts in adults

BACKGROUND: Idiopathic arachnoid cysts are rare lesions not associated with trauma or other inflammatory insults. To date, there have been few large series describing the presentation and management of these lesions. METHODS: Twenty-one cases of intradural spinal arachnoid cysts were identified (1994-2001). Pediatric patients and cases with antecedent trauma were excluded. There were eight women and 13 men with an average age of 52 years. Follow-up averaged 17 months. RESULTS: Cysts were most commonly found in the thoracic spine (81%). Fifteen cysts were dorsal to the spinal cord and six were ventral to the spinal cord. All patients underwent laminectomy with cyst fenestration and radical cyst wall resection. Based upon intraoperative ultrasonography, four cysts were also shunted to the subarachnoid space, and seven patients had an expansile duraplasty with freeze-dried dural allograft. Of the seven patients with syringomyelia, three resolved with extramedullary cyst resection alone. Four required syrinx to subarachnoid shunting. Follow-up MRI demonstrated cyst resolution in all cases. All seven intramedullary syrinxes were decreased in size and four resolved completely. Weakness (100%), hyperreflexia (91%), and incontinence (80%) were more likely to improve than neuropathic pain (44%) and numbness (33%). One patient had increased numbness postoperatively. CONCLUSIONS: Ventral cysts are more likely to cause weakness and myelopathic signs. Preoperative symptoms of neuropathic pain and numbness are less likely to improve than weakness and myelopathy. Utilizing intraoperative ultrasound to guide aggressive surgical treatment with the adjuncts of shunting and duraplasty results in a high rate of cyst and syrinx obliteration.     

To shunt or to fenestrate: which is the best surgical treatment for arachnoid cysts in pediatric patients?

The treatment options for intracranial arachnoid cysts are either craniotomy and fenestration of the cyst into the cerebrospinal fluid spaces or shunting of the cyst contents extracranially. Fenestration may eliminate the need to shunt, but it is a major operative procedure and is not always successful. To determine which treatment provides the greatest benefit with the fewest complications, the records of 31 patients with 34 arachnoid cysts treated at the Children's Hospital of Los Angeles between 1976 and 1986 were reviewed. The mean age of the patients was 4.4 years, with a range of 0 to 15.5 years. The most common location was the middle fossa (14 cases), followed by the posterior fossa (7 cases), the suprasellar region (5 cases), and hemispheric (5 cases) and other locations (3 cases). Signs and symptoms were related to abnormally rapid head growth in infants and to increased intracranial pressure and seizures in older children. The initial treatment of 29 cysts was fenestration. Twenty-two (76%) procedures were successful, with no additional treatment needed for the cyst. The other 7 cysts required the subsequent placement of a cystoperitoneal shunt. In 5 cases, the cysts were treated initially with cystoperitoneal shunts. Of the total 12 cystoperitoneal shunts, 5 have required revisions on one or more occasions. No significant difference in morbidity was noted between the two treatment options. Because we consider shunt independence to be a major goal of therapy, we suggest that patients with arachnoid cysts be divided into two categories, those presenting with associated hydrocephalus and those without hydrocephalus.(ABSTRACT TRUNCATED AT 250 WORDS)     

Shunting procedures in the management of intracranial cerebrospinal fluid cysts in infancy and childhood

Summary Widely diverging opinions on the optimal therapy for intracranial cerebrospinal fluid cysts (CSF), mainly arachnoid cysts and the Dandy-Walker cysts, exist. Excision of the cyst walls in the treatment of the Dandy-Walker cyst has been replaced by shunting procedures, but the recommended method for primary treatment of arachnoid cysts in childhood is still cyst wall excision. Membrane excision is, however, often complicated by recurrence, subsequently requiring shunting-procedures. In a series of 19 cases primary shunting of intracranial CSF cysts proved to be a reliable method. In those cases where hydrocephalus (ventricular dilatation) is present at the time of the primary operation the ventricles should be shunted as well as the cyst. The catheter from the ventricle and that from the cyst should be connected to the same valve, otherwise an increased risk of intracranial herniation exists. The prognosis for infants and children suffering from intracranial CSF cysts is in general good; in 17 out of 19 cases mental development was normal and in 15 out of 19 motor development was normal. The risk of permanent motor damage seems to be particularly high when an arachnoid cyst is located on the quadrigeminal plate.     

Arachnoid cyst is a risk factor for chronic subdural hematoma in juveniles: twelve cases of chronic subdural hematoma associated with arachnoid cyst

Chronic subdural hematoma (CSDH) tends to occur in elderly patients with a history of mild head injury at a few months prior to the onset of symptoms. Intracranial arachnoid cyst is believed to be congenital and sometimes becomes symptomatic in pediatric patients. These two distinct clinical entities sporadically occur in the same young patient. Twelve of 541 cases of CSDH surgically treated in our institution had associated arachnoid cyst. The clinical and radiological characteristics of the cases of CSDH associated with arachnoid cyst were retrospectively analyzed and compared with those of CSDH without arachnoid cyst. Arachnoid cysts were located in the middle fossa (eight cases), convexity (two cases), and posterior fossa (two cases). Three cysts were less than 20 mm in diameter. The 12 patients with CSDH and arachnoid cyst (mean age 27.8 +/- 19.7 years) were significantly younger (p < 0.001) than the patients with CSDH without arachnoid cyst (69.5 +/- 13.7 years). Five of the 12 patients were pediatric cases (< 15 years old). The clinical symptoms were also significantly different. The most frequent symptom was headache followed by vomiting in the patients with arachnoid cyst, while gait disturbance and hemiparesis predominated in patients without arachnoid cyst. Hematoma evacuation through burr holes improved the symptoms in all patients with arachnoid cyst. We conclude that even a small arachnoid cyst can be a risk factor for CSDH after mild head injury in young patients and symptoms of increased intracranial pressure are common. Hematoma evacuation is adequate at first operation. If the preoperative symptoms persist, additional arachnoid cyst surgery should be considered. The present results also suggest that CSDH formation may be preceded by subdural hygroma caused by the rupture of arachnoid cyst.     

Microsurgical keyhole approach for middle fossa arachnoid cyst fenestration

OBJECTIVE: The optimal surgical treatment for symptomatic temporal arachnoid cysts is controversial. Therapeutic options include cyst shunting, endoscopic fenestration, and craniotomy for fenestration. We reviewed the results for patients who were treated primarily with craniotomy and fenestration at our institution, to provide a baseline for comparisons of the efficacies of other treatment modalities. METHODS: A retrospective review of data for 50 children who underwent keyhole craniotomy for fenestration of temporal arachnoid cysts between 1994 and 2001 was performed after institutional review board approval. During that period, the first-line treatment for all symptomatic middle fossa arachnoid cysts was microcraniotomy for fenestration. Microsurgical dissection to create communications between the cyst cavity and basal cisterns was the goal. All patient records were reviewed and numerous variables related to presentation, cyst size and classification, treatment, cyst resolution, symptom resolution, follow-up periods, and cyst outcomes were recorded. RESULTS: Fifty temporal arachnoid cysts in 50 treated patients were identified. The average age at the time of surgery was 68 +/- 57.2 months. The follow-up periods averaged 36 months. There were 34 male and 16 female patients in the series. Twenty-six cysts were on the left side. Indications for surgery included intractable headaches (45%), increasing cyst size (21%), seizures (25%), and hemiparesis (8%). The symptoms most likely to improve were hemiparesis (100%) and abducens nerve palsies. Headaches (67%) and seizure disorders (50%) were less likely to improve. Nine patients exhibited progressive increases in cyst size in serial imaging studies. Those patients were monitored for a mean of 40 +/- 23 months before intervention. In the entire series, 82% of patients demonstrated decreases in cyst size in serial imaging studies. Of those patients, 18% demonstrated complete cyst effacement. Overall, 83% of patients with Grade II cysts and 75% of patients with Grade III cysts exhibited evidence of decreases in cyst size in long-term monitoring. Two patients required shunting after craniotomy (4%). Hospital stays averaged 3.4 days. Total surgical times averaged 115 minutes. No significant blood loss occurred (5-50 ml). Complications included spontaneously resolving pseudomeningocele (10%), transient Cranial Nerve III palsy (6%), cerebrospinal fluid leak (6%), subdural hematoma (4%), and wound infection (2%). CONCLUSION: A microsurgical keyhole approach to arachnoid cyst fenestration is a safe effective method for treating middle fossa cysts. This procedure can be performed with minimal morbidity via a minicraniotomy. Compared with an endoscopic approach, better control of hemostasis can be obtained, because of the ability to use bipolar forceps and other standard instruments. The operative time and length of hospital stay were not excessively increased.     

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.     

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.     

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.     

微创脑室——腹腔分流术

目的 探讨微创下脑室—腹腔分流术治疗脑积水、蛛网膜囊肿的方法。方法 1991年1月至2000年12月,采用自制通条和带裂隙的腹腔套管刺针行微创脑室(或囊肿)-腹腔分流术286例。结果 本组病人均一次手术成功,无出血、感染、腹腔脏器损伤、肠粘连等手术并发症。术后1—2周复查头颅CT或脚,脑积水均消失或蛛网膜囊肿明显减小,引流管通畅。结论 微创脑室-腹腔分流术简便,创伤小,效果良好。     

Endoscopic treatment of prepontine arachnoid cysts

Prepontine (or suprasellar) arachnoid cysts are uncommon in clinical practice and experience in their management may therefore be limited. Symptomatic cysts usually present with features of hydrocephalus due to obstruction of the third ventricle and aqueduct, and occlusion or partial obstruction of both foramina of Monro. Several treatment techniques have been used including stereotactic aspiration, microsurgical excision and shunting, but the best method of treatment remains unclear and the role of endoscopy is not yet established. We report our experience in a series of seven patients who had endoscopic treatment for prepontine arachnoid cysts; five were children under 15 years old who presented with delayed development and/or enlarged heads. The two adult patients, both of whom had insertion of shunts as children, presented with headache and vomiting due to shunt blockage. All patients improved following endoscopic cyst fenestration. There was no operative morbidity and there have been no relapses to date. Endoscopic fenestration of prepontine arachnoid cysts appears to be an effective method of treatment.     

Double-endoscopic approach for management of convexity arachnoid cyst: case report

BACKGROUND: Controversy exists about the best treatment modality for arachnoid cysts. Widely accepted neurosurgical options include craniotomy with open resection of the cyst walls, shunting procedures and stereotactic fenestration of the cyst cavity. Recently, neuroendoscopic approach showed its effectiveness for treatment of these lesions. CASE DESCRIPTION: In the presented case the large convexity arachnoid cyst was diagnosed in a 22-year-old woman with head dullness and local bone bulging. No neurologic signs were found. Surgery was performed by double-neuroendoscopic approach with simultaneous use of two flexible ventriculofiberscopes, which permitted wide resection of the inner cyst wall. Complete resolution of symptoms was noted soon after surgery. CONCLUSION: Double-endoscopic approach might be useful for complex neuroendoscopic procedures that need different simultaneous surgical actions, particularly for cases of large arachnoid cysts.     

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.     

Supratentorial arachnoid cysts: Clinical and therapeutic remarks on 46 cases

Summary The authors report 46 cases of primary supratentorial arachnoid cysts. Thirty-two patients presented with symptomatic arachnoid cysts, which act as space-occupying lesions and were surgically treated by fenestration. 14 patients presented with a scarsity of symptoms; for this reason they were kept under control by periodical neuroradiological examination. After a long follow-up period (median 11 years), 97% of the operated patients presented neurological improvement and a decrease in the size of the cyst; none of the patients who were not operated on showed any variation in either neurological status or size of the cyst. The authors discuss their findings in the light of the published papers.