CSF overdrainage in shunted intracranial arachnoid cysts: a series and review

Reduction Cranioplasty in Cases of Hydrocephalic Macrocephaly: Pearls and Pitfalls of Computer-Assisted Surgery

Reduction cranioplasty may be indicated to address functional or cosmetic sequelae of hydrocephalic macrocephaly. With the advent of CAD/CAM digital workflow, surgeons can design and fabricate craniotomy guides, templates, and models that allow for precise cranial reconstruction. Although there are several advantages of virtual planning, pre-determined surgical plans may limit intraoperative flexibility, requiring surgeons to troubleshoot errors in pre-operative planning or model design. The purpose of this report is to present a series of cases demonstrating our institution's technique for single-stage reduction cranioplasty using a CAD/CAM workflow. This report will highlight the benefits and challenges associated with a contemporary digital workflow for reduction cranioplasty.

Is foramen magnum decompression for acquired Chiari I malformation like putting a finger in the dyke? - A simplistic overview of artificial intelligence in assessing critical upstream and downstream etiologies

Background

Missed diagnosis of evolving or coexisting idiopathic (IIH) and spontaneous intracranial hypotension (SIH) is often the reason for persistent or worsening symptoms after foramen magnum decompression for Chiari malformation (CM) I. We explore the role of artificial intelligence (AI)/convolutional neural networks (CNN) in Chiari I malformation in a combinatorial role for the first time in literature, exploring both upstream and downstream magnetic resonance findings as initial screening profilers in CM-1. We have also put together a review of all existing subtypes of CM and discuss the role of upright (gravity-aided) magnetic resonance imaging (MRI) in evaluating equivocal tonsillar descent on a lying-down MRI. We have formulated a workflow algorithm MaChiP 1.0 (Manjila Chiari Protocol 1.0) using upstream and downstream profilers, that cause de novo or worsening Chiari I malformation, which we plan to implement using AI.

Materials and Methods

The PRISMA guidelines were used for "CM and machine learning and CNN" on PubMed database articles, and four articles specific to the topic were encountered. The radiologic criteria for IIH and SIH were applied from neurosurgical literature, and they were applied between primary and secondary (acquired) Chiari I malformations. An upstream etiology such as IIH or SIH and an isolated downstream etiology in the spine were characterized using the existing body of literature. We propose the utility of using four selected criteria for IIH and SIH each, over MRI T2 images of the brain and spine, predominantly sagittal sequences in upstream etiology in the brain and multiplanar MRI in spinal lesions.

Results

Using MaChiP 1.0 (patent/ copyright pending) concepts, we have proposed the upstream and downstream profilers implicated in progressive Chiari I malformation. The upstream profilers included findings of brain sagging, slope of the third ventricular floor, pontomesencephalic angle, mamillopontine distance, lateral ventricular angle, internal cerebral vein-vein of Galen angle, and displacement of iter, clivus length, tonsillar descent, etc., suggestive of SIH. The IIH features noted in upstream pathologies were posterior flattening of globe of the eye, partial empty sella, optic nerve sheath distortion, and optic nerve tortuosity in MRI. The downstream etiologies involved spinal cerebrospinal fluid (CSF) leak from dural tear, meningeal diverticula, CSF-venous fistulae, etc.

Conclusion

AI would help offer predictive analysis along the spectrum of upstream and downstream etiologies, ensuring safety and efficacy in treating secondary (acquired) Chiari I malformation, especially with coexisting IIH and SIH. The MaChiP 1.0 algorithm can help document worsening of a previously diagnosed CM-1 and find the exact etiology of a secondary CM-I. However, the role of posterior fossa morphometry and cine-flow MRI data for intracranial CSF flow dynamics, along with advanced spinal CSF studies using dynamic myelo-CT scanning in the formation of secondary CM-I is still being evaluated.

Effect of continuous drainage of cranial arachnoid cysts into the ventricular system by stereotactic placed catheters

Background: Surgical treatment of intracranial arachnoid cysts (iACs) is challenging. Microsurgical resection, endoscopic fenestration and cysto-peritoneal shunting are the most frequently used methods, each implying their own drawbacks. Stereotactic-guided cysto-ventricular drainage has been described as an alternative method. Here we describe our experience with this technique and how we conducted volumetric measurements to evaluate the effect of permanent drainage.Methods: Standardized stereotactic planning was performed. The planned trajectory included both the iAC and the ventricle system. The catheter was shortened to the defined length and was further fenestrated along its planned course through the iAC to allow drainage into the ventricular system. Clinical and radiological control was performed on outpatient basis after a mean follow-up of 2 (1-3) months. The overall mean follow-up was 32 months (6-59). The measurement of the cyst volume was conducted by the ABC/2-method.Results: Six patients with symptomatic arachnoid cysts (4 f, 2 m) were treated between 2010 and 2016. The overall postoperative reduction in cyst volume at the first follow-up was 36.04% (at the long-term follow-up: 38.57%). Decrease of the midline-shift was achieved in all cases and averaged 57.83% (long term: 81.88%). Clinical improvement of related symptoms could be achieved in all patients (4 patients were symptom free, two patients had alleviated symptoms). There was no case of over-drainage. The catheter had to be removed after 6 months in one case due to infection.Conclusions: We demonstrate successful symptom control and volume reduction in a small series of iACs by continuous drainage into the CSF-system through stereotactic placed catheters. This method may facilitate a self-regulated egress of entrapped cyst fluid in symptomatic patients without risk of over-drainage. A literature survey of the success rate and the complications of this approach is provided. It is concluded that this minimally- invasive method may be an alternative to established fenestration techniques especially for patients with arachnoid cysts that aren't directly adjacent to a cisternal or ventricular CSF space.

Intracranial arachnoid cysts: What is the appropriate surgical technique? A retrospective comparative study with 61 pediatric patients

Objective

Symptomatic intracranial arachnoid cysts (ACs) should be treated either through microsurgical (MS) or endoscopic surgical (ES) fenestration. Implantation of cysto-peritoneal shunt (CPS) system is another treatment option with decreasing indication. In our study, we compared the complication and revision rates between the three operative techniques in pediatric patients.

Methods

We included patients below 18 years with symptomatic intracranial ACs operated between 2004 and 2021. Initial symptoms, location, complication rate, clinical and radiological improvement, postoperative events and revision rate were compared retrospectively.

Results

Sixty-one patients; 33 (54.1%) MS operated (mean age 7.6 years), 18 (29.5%) ES operated (mean age 6.2 years) and 10 (16.4%) with CPS (mean age 3.0 years) were collected. The most common initial symptom was headache in 45.9%. 20 (32.8%) postoperative events were documented. The highest revision rate (60%) was seen in the CPS group compared to 33.3% in MS group and 16.7% in ES group. 31 patients harbored perisylvian ACs, 89% remained event-free after ES, 71% after MS and 20% after CPS. Clinical improvement immediately after surgery was observed in 58 patients (96.9% in MS, 88.9% in ES and 100% in CPS). A radiological volume reduction could be proven postoperative in 51 patients (78.8% MS, 88.9% ES and 90% CPS).

Conclusion

Endoscopic fenestration of AC is a safe and efficient technique which is being widely used nowadays with the highest event free survival compared to microsurgical fenestration especially in perisylvian arachnoid cysts. CPS shows on long terms the highest revision rate but carries the least surgical risks.

Frame-based stereotactic implantation of cystoventricular shunts for treating acquired intracerebral cysts

OBJECTIVE

The treatment of symptomatic, progressive or recurrent acquired intracerebral cysts is challenging, especially when they are localized in eloquent structures. In addition to resection, endoscopic fenestration, or stereotactic puncture, the implantation of a cystoventricular shunt by stereotactic guidance (SCVS) has been reported as a minimally invasive procedure; however, only scarce data are available regarding its feasibility and efficacy. Here, the authors evaluated the feasibility and efficacy of frame-based SCVS in patients with acquired intracranial cysts.

METHODS

In this single-center retrospective analysis, the authors included all patients with acquired intracerebral cysts treated by SCVS following a standardized prospective protocol between 2012 and 2020. They analyzed clinical symptoms, complications, and radiological outcome with regard to cyst volume reduction by 3D volumetry.

RESULTS

Thirty-four patients (17 females and 17 males; median age 44 years, range 5-77 years) were identified. The median initial cyst volume was 11.5 cm3 (range 1.6-71.6 cm3), and the mean follow-up was 20 months (range 1-82 months). At the last follow-up, 27 of 34 patients (79%) showed a cyst volume reduction of more than 50%. Initial symptoms improved or resolved in 74% (n = 25) and remained stable in 24% (n = 8). No permanent clinical deterioration after treatment was observed. The total complication rate was 5.9%, comprising transient neurological deterioration (n = 1) and ventriculitis (n = 1). There were no deaths. The overall recurrence rate was 11.8%.

CONCLUSIONS

In this study, SCVS proved to be a safe, minimally invasive, and effective treatment with reliable long-term volume reduction, resulting in clinical improvement and a minor complication rate.

Midline Brain Shift After Hemispheric Surgery: Natural History, Clinical Significance, and Association With Cerebrospinal Fluid Diversion

BACKGROUND

Hemispherectomy and its modern variants are effective surgical treatments for medically intractable unihemispheric epilepsy. Although some complications such as posthemispherectomy hydrocephalus are well documented, midline brain shift (MLBS) after hemispheric surgery has only been described anecdotally and never formally studied.

OBJECTIVE

To assess the natural history and clinical relevance of MLBS and determine whether cerebrospinal fluid (CSF) shunting of the ipsilateral surgical cavity exacerbates MLBS posthemispheric surgery.

METHODS

A retrospective review of consecutive pediatric patients who underwent hemispheric surgery for intractable epilepsy and at least 6 months of follow-up at UCLA between 1994 and 2018 was performed. Patients were grouped by MLBS severity, shunt placement, valve type, and valve opening pressure (VOP). MLBS was evaluated using the paired samples t-test and analysis of covariance adjusting for follow-up time and baseline postoperative MLBS.

RESULTS

Seventy patients were analyzed, of which 23 (33%) required CSF shunt placement in the ipsilateral surgical cavity for posthemispherectomy hydrocephalus. MLBS increased between first and last follow-up for nonshunted (5.3 ± 4.9-9.7 ± 6.6 mm, P < .001) and shunted (6.6 ± 3.5-16.3 ± 9.4 mm, P < .001) patients. MLBS progression was greater in shunted patients (P = .001). Shunts with higher VOPs did not increase MLBS relative to nonshunted patients (P = .834), whereas MLBS increased with lower VOPs (P = .001). Severe MLBS was associated with debilitating headaches (P = .048).

CONCLUSION

Patients undergoing hemispheric surgery often develop postoperative MLBS, ie, exacerbated by CSF shunting of the ipsilateral surgical cavity, specifically when using lower VOP settings. MLBS exacerbation may be related to overshunting. Severe MLBS is associated with debilitating headaches.

Shunt Overdrainage: Reappraisal of the Syndrome and Proposal for an Integrative Model

Although shunt overdrainage is a well-known complication in hydrocephalus management, the problem has been underestimated. Current literature suggests that the topic requires more examination. An insight into this condition is limited by a lack of universally agreed-upon diagnostic criteria, heterogeneity of published series, the multitude of different management options and misunderstanding of relationships among pathophysiological mechanisms involved. We carried out a review of the literature on clinical, radiological, intracranial pressure (ICP), pathophysiological and treatment concepts to finally propose an integrative model. Active prophylaxis and management are proposed according to this model based on determination of pathophysiological mechanisms and predisposing factors behind each individual case. As pathophysiology is progressively multifactorial, prevention of siphoning with gravitational valves or antisiphon devices is mandatory to avoid or minimize further complications. Shunt optimization or transferal and neuroendoscopy may be recommended when ventricular collapse and cerebrospinal fluid isolation appear. Cranial expansion may be useful in congenital or acquired craniocerebral disproportion and shunting the subarachnoid space in communicating venous hydrocephalus and idiopathic intracranial hypertension.

Paediatric arachnoid cysts: Surgical outcomes from a Singapore children's hospital

Arachnoid cysts (AC) are reported to have a prevalence of up to 2.6% in children. Most AC remain indolent, but others may expand or rupture to cause life-threatening symptoms of raised intracranial pressure. Currently, there are 2 controversial topics with regards to the management of ACs: the indications for surgery and the choice of surgical procedure. We therein report our institution's neurosurgical experience for symptomatic AC over a 22-year period and corroborate our results with published literature. This is a single institution, retrospective study conducted at KK Women's and Children's Hospital from 01 January 1998 to 31 December 2019. A total of 38 patients with ACs that required surgery were recruited. The 3 most common anatomical locations were in the middle cranial fossa (40.5%), posterior fossa (24.3%) and interhemispheric (13.5%). Typical clinical presentations included symptoms of raised intracranial pressure (34.2%), obstructive hydrocephalus (28.9%) and AC rupture (21.1%). Surgical approaches included 17 craniotomy-based procedures, 7 endoscopic fenestrations, 11 cystoperitoneal shunts, 2 burrhole drainage operations and 1 excision of spinal AC. Thirteen patients (34.2%) underwent either another operation due to the lack of resolution of their AC-related symptoms or secondary to complications directly related to their initial surgery. Average length of followup from time of first operation was 84.1 months. Overall, our results demonstrate similarities in epidemiology, clinical presentation and surgical experience, in comparison to larger cohort studies. We advocate collaborative efforts to better understanding of the pathophysiology of paediatric ACs, particularly for deciding between the various surgical treatment modalities.

Coexisting Retrocerebellar Arachnoid Cyst and Chiari Type 1 Malformation: 3 Pediatric Cases of Surgical Management Tailored to the Pathogenic Mechanism and Systematic Review of the Literature

INTRODUCTION

Arachnoid cysts are benign cerebrospinal fluid collection within a duplication of arachnoid membrane and, when found in the retrocerebellar site, they may be associated with tonsils herniation. This rare situation of coexisting retrocerebellar arachnoid cyst (AC) and Chiari malformation type 1 (CM-1) have been previously reported in few cases (10 patients) with syringomyelia and hydrocephalus described to be the most relevant issues. The aim of this paper is to describe 3 pediatric cases of this condition with a systematic review of the literature, underlining the importance of surgical management tailored to the pathogenic mechanism.

METHODS

A restrospective analysis of patients treated for coexisting CM-1 and ACs at the authors' institution has been carried out.

RESULTS

A case of a 10-month-old baby with coexisting AC and CM-1 with tri-ventricular hydrocephalus treated with endoscopic third ventriculostomy, a case of a 1-year-old child with a huge retrocerebellar AC and CM-1 treated with a cysto-peritoneal shunt, and a case of a 15-year-old child with retrocerebellar AC causing symptomatic CM-1 treated with C0-C2 decompression, AC fenestration and duraplasty are described. A long-term follow-up is reported.

CONCLUSIONS

Surgical management of coexisting ACs and CM-1 should not aim at the complete resolution of the cyst or of tonsil herniation, especially when pediatric patients are treated. Rather, the purpose of the neurosurgeon should be to understand the underlying pathogenic mechanism, and then restoring both the cerebrospinal fluid flow in the posterior fossa and the dynamic equilibrium between ventricles, cyst, and subarachnoid space.

Acquired Chiari type I malformation managed by expanding posterior fossa volume and literature review

PURPOSE

The acquired Chiari type I malformation is a rare late complication of supratentorial shunting in children which is often accompanied by abnormal cranial vault thickening. Several surgical treatments for this disease have been proposed including supratentorial skull enlarging procedures and subtentorial craniotomy. But there is still debate about the best treatment strategy for this disease.

METHOD AND RESULTS

We reviewed the current knowledge of this disease in the paper. We illustrated one patient of symptomatic acquired Chiari type I malformation who had cysto-peritoneal (C-P) shunting and ventriculoperitoneal (V-P) shunting. We observed the CSF flow dynamic of this patient at different periods. The acquired Chiari type I malformation disappeared on imaging after thinning the occipital planum combined with the standard surgical therapy of Chiari decompression. The symptoms of the patient were relieved after surgery.

CONCLUSION

Overshunting manifestations require prompt recognition and management. Preventive measures should be taken which include making a stringent selection of cases being considered for surgery, avoiding C-P drainage, and placing of a programmable valve as initial treatment of intracranial arachnoid cysts (AC) if shunting is considered.

The role of lumboperitoneal shunts in managing chronic hydrocephalus with slit ventricles

OBJECTIVELumboperitoneal (LP) shunts have a role not only in pseudotumor cerebri, but also in patients with slit-like ventricles who are treated with CSF shunting on a chronic basis. Hesitation to utilize LP shunts is based on previous conventional beliefs including the tendency for overdrainage, difficulties accessing the shunt to tap or revise, and risk of progressive cerebellar tonsillar herniation. The authors hypothesized that the use of horizontal-vertical (HV) valves may reduce the risk of these complications, particularly overdrainage and development of Chiari malformation.METHODSAll pediatric cases involving patients treated with an LP shunt at the Children's Hospital of Michigan were reviewed in this retrospective case series. A total of 143 patients with hydrocephalus were treated with LP shunts from 1997-2015 (follow-up range 8 months-8 years, median 4.2 years). Patients with pseudotumor cerebri underwent placement of an LP shunt as a primary procedure. In patients with slit ventricles from chronically treated hydrocephalus or repeated shunt malfunctions from proximal catheter obstruction, a lumbar drain was inserted to assess candidacy for conversion to an LP shunt. In patients who tolerated the lumbar drain and demonstrated communication of the ventricles with the spinal cisterns, treatment was converted to an LP shunt. All patients included in the series had undergone initial shunt placement between birth and age 16 years.RESULTSIn 30% of patients (n = 43), LP shunts were placed as the initial shunt treatment; in 70% (n = 100), treatment was converted to LP shunts from ventriculoperitoneal (VP) shunts. The patients' age at insertion of or conversion to an LP shunt ranged from 1 to 43 years (median 8.5 years). Of the patients with clear pre-LP and post-LP shunt follow-up imaging, none were found to develop an acquired Chiari malformation. In patients with pre-existing tonsillar ectopia, no progression was noted on follow-up MRIs of the brain in these patients after LP shunt insertion. In our LP shunt case series, no patient presented with acute deterioration from shunt malfunction.CONCLUSIONSConversion to an LP shunt may minimize acute deterioration from shunt malfunction and decrease morbidity of repeated procedures in patients with chronically shunt-treated hydrocephalus and small ventricles. In comparison to previously published case series of LP shunt treatment, the use of LP shunts in conjunction with HV valves may decrease the overall risk of cerebellar tonsillar herniation. The use of an LP shunt may be an alternative in the management of slit ventricles when VP shunting repeatedly fails.

Transtentorial Distortion Syndrome: Consistent Complication Following Lateral and Fourth Ventricular Shunting in Adults

BACKGROUND

Complex hydrocephalus affecting lateral and fourth ventricles separately is occasionally managed with cerebrospinal fluid diversion via supratentorial and infratentorial ventricular catheters. The optimal configuration to reduce complications is currently unknown in adults. We describe a consistently similar clinical presentation of patients with complex hydrocephalus and a fourth ventricle separately drained by infratentorial shunt insertion.

METHODS

This was a retrospective single-center case series. Medical notes were reviewed for clinical presentation, brain imaging, and neurophysiologic tests results. All patients underwent intracranial pressure monitoring (ICPM). Outcomes were determined by ventricular appearance on brain imaging computed tomography and symptomatic improvements postoperatively.

RESULTS

Five adult patients referred to the hydrocephalus service had separate infratentorial and supratentorial shunt systems. A common clinical presentation was observed, including lower motor neuron facial palsy (confirmed with electrophysiology), ophthalmoplegia, dysarthria, impaired gait headache, and nausea. We refer to this as transtentorial distortion syndrome. Twenty-four-hour ICPM demonstrated clear low pressures. All patients underwent shunt revision connecting the transtentorial shunts via a Y-connector and the addition of a distal valve. All subjects had improved ventricular appearance on computed tomography scans post revision, and normalization of ICPM was observed. In the follow-up period of 6 months, no patient required further shunt revision.

CONCLUSION

To prevent transtentorial distortion syndrome, supratentorial and infratentorial shunt constructs in adults with encysted fourth ventricles should be similar to the shunt systems widely known in the pediatric population with Dandy-Walker syndrome (i.e., joint output to a single valve distal to the connection of the 2 proximal drainage catheters).

A novel technique to treat acquired Chiari I malformation after supratentorial shunting

PURPOSE

The acquired Chiari I malformation with abnormal cranial vault thickening is a rare late complication of supratentorial shunting. It poses a difficult clinical problem, and there is debate about the optimal surgical strategy. Some authors advocate supratentorial skull enlarging procedures while others prefer a normal Chiari decompression consisting of a suboccipital craniectomy, with or without C1 laminectomy and dural patch grafting.

METHODS

We illustrate three cases of symptomatic acquired Chiari I malformation due to inward cranial vault thickening.

RESULTS

We describe a new surgical approach that appears to be effective in these patients. This approach includes the standard Chiari decompression combined with posterior fossa augmentation by thinning the occipital planum.

CONCLUSION

Internal volume re-expansion of the posterior fossa by thinning the occipital planum appears to be an effective novel surgical strategy in conjunction with the standard surgical therapy of Chiari decompression.

Stricter indications are recommended for fenestration surgery in intracranial arachnoid cysts of children

PURPOSE

The indication of surgical treatment for intracranial arachnoid cysts (ACs) is a controversial issue. In this study, we reviewed surgical outcomes of intracranial ACs that were treated with endoscopic fenestration or microscopic fenestration, which are currently standard practices for surgical treatment of AC. In addition, we also evaluated the validity of current surgical indications.

METHODS

We analyzed pediatric patients under 18 years of age who underwent surgical management for intracranial AC between January 2000 and December 2011. Patients with a follow-up period of less than 1 year were excluded. A total of 75 patients were enrolled in this study. These patients were assessed by subjective symptoms and by a clinician's objective evaluation. The radiological assessment of AC after surgery was also evaluated.

RESULTS

The median age of patients at the initial operation was 5 years. The median follow-up period was 38 months. The goal of surgery was achieved in 28% (21/75) of patients. The radiological alteration of AC after initial fenestration surgery was diverse. The results of the clinical and radiological assessments did not always coincide. A total of 35 complications occurred in 28 patients. Subdural fluid collection was the most common unexpected radiological complication.

CONCLUSIONS

Our study showed that the fenestration procedure for AC produced unsatisfactory clinical improvements compared to the relatively high complication rate. Therefore, surgical treatment for AC should be strictly limited to patients who have symptoms directly related to AC.

Management of subdural hygromas associated with arachnoid cysts

OBJECT

Arachnoid cysts may occasionally be associated with subdural hygromas. The management of these concurrent findings is controversial.

METHODS

The authors reviewed their experience with arachnoid cysts and identified 8 patients with intracranial arachnoid cysts and an associated subdural hygroma. The medical records and images for these patients were also examined.

RESULTS

In total, 8 patients presented with concurrent subdural hygroma and arachnoid cyst. Of these 8 patients, 6 presented with headaches and 4 had nausea and vomiting. Six patients had a history of trauma. One patient was treated surgically at the time of initial presentation, and 7 patients were managed without surgery. All patients experienced complete resolution of their presenting signs and symptoms.

CONCLUSIONS

Subdural hygroma may lead to symptomatic presentation for otherwise asymptomatic arachnoid cysts. The natural course of cyst-associated subdural hygromas, even when symptomatic, is generally benign, and symptom resolution can be expected in most cases. The authors suggest that symptomatic hygroma is not an absolute indication for surgical treatment and that expectant management can result in good outcomes in many cases.

Slit ventricle syndrome: a case report of intermittent intracranial hypertension

Slit ventricle syndrome is a rare condition whereby brain compliance is reduced and can be associated with intermittent intracranial hypertension. A 19-year-old male with a ventriculoperitoneal shunt for congenital hydrocephalus presented with a 1-day history of headache and drowsiness-symptoms from which he suffered in many recurrent episodes over the past 5 years. The improvement of headaches without surgical intervention led to the diagnosis of migraine. During this hospitalization, episodes of intermittent intracranial hypertension were documented along with the remission and relapse of the symptoms. While the patient's intracranial pressure was within normal range in over 90% of his monitoring period, which postponed shunting, replacement of his ventriculoperitoneal shut eventually resolved his symptoms. Slit ventricle syndrome with reduced ventricular compliances should be considered in patients with clinical evidence of intermittent intracranial hypertension and small ventricular size. The authors advocate shunt replacement as an appropriate treatment for this condition.

Prevalence and natural history of arachnoid cysts in adults

Object

Arachnoid cysts are a frequent finding on intracranial imaging. The prevalence and natural history of these cysts in adults are not well defined.

Methods

We retrospectively reviewed the electronic medical records of a consecutive series of adults who underwent brain MRI over a 12-year interval to identify those with arachnoid cysts. The MRI studies were reviewed to confirm the diagnosis. For those patients with arachnoid cysts, we evaluated presenting symptoms, cyst size, and cyst location. Patients with more than 6 months' clinical and imaging follow-up were included in a natural history analysis.

Results

A total of 48,417 patients underwent brain MRI over the study period. Arachnoid cysts were identified in 661 patients (1.4%). Men had a higher prevalence than women (p < 0.0001). Multiple arachnoid cysts occurred in 30 patients. The most common locations were middle fossa (34%), retrocerebellar (33%), and convexity (14%). Middle fossa cysts were predominantly left-sided (70%, p < 0.001). Thirty-five patients were considered symptomatic and 24 underwent surgical treatment. Sellar and suprasellar cysts were more likely to be considered symptomatic (p < 0.0001). Middle fossa cysts were less likely to be considered symptomatic (p = 0.01. The criteria for natural history analysis were met in 203 patients with a total of 213 cysts. After a mean follow-up of 3.8 ± 2.8 years (for this subgroup), 5 cysts (2.3%) increased in size and 2 cysts decreased in size (0.9%). Only 2 patients developed new or worsening symptoms over the follow-up period.

Conclusions

Arachnoid cysts are a common incidental finding on intracranial imaging in all age groups. Although arachnoid cysts are symptomatic in a small number of patients, they are associated with a benign natural history for those presenting without symptoms.

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

OBJECT

The authors present a single-institution experience in shunt treatment for arachnoid cysts (ACs).

METHODS

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.

RESULTS

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%).

CONCLUSIONS

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.

Enlarging arachnoid cyst: a false alarm for infants

PURPOSE

The natural history of change in size of arachnoid cysts (ACs) is an unsettled issue. This leads to confusion in deciding treatment strategies of incidental, asymptomatic AC in children, since the risks and complications of surgery are not negligible. The aim of the present study was to elucidate the clinical significance of change in size of AC in young children.

METHODS

From 2000 to 2008, 86 patients younger than 5 years with AC documented on brain imaging were included. They were divided into four different age groups (group I: 0-0.5 year, group II: 0.5-1 year, group III: 1-3 years, group IV: 3-5 years). The temporal changes in size of the AC on consecutive ultrasonography, computed tomography (CT), or magnetic resonance imaging (MRI) of each patient were measured and plotted as individual graphs. Natural progression of AC size was assessed by evaluation of the pattern of each graph.

RESULTS

Seventeen patients showed enlargement of AC during follow-up; 14 patients were younger than 1 year. None of the patients in group IV showed enlargement during follow-up. Overall, 11 of the 17 patients with demonstrated AC enlargement were not operated on. In six patients, AC enlargement ceased, and spontaneous regression was observed in three patients. The remaining two untreated patients had shown asymptomatic increase in size at last follow-up. Statistical analysis revealed age at diagnosis to be the only significant factor affecting cyst enlargement.

CONCLUSION

Asymptomatic enlargement of AC in infants may not be an indication for surgical intervention. Close follow-up is a viable option for such children.

Hydrocephalus and arachnoid cysts

AIM

The management of arachnoid cysts (AC) remains controversial. An additional problem derives from the management of hydrocephalus associated with an AC. In this work, we discuss existing procedures proposed in the current literature for their treatment.

METHODS

We reviewed selected reports on intracranial ACs placing special interest in those about the association of hydrocephalus and ACs. We also briefly surveyed data of our patients with this association.

RESULTS AND DISCUSSION

Hydrocephalus is often found in midline and posterior fossa ACs. Interhemispheric lesions may also evolve with ventriculomegaly, while middle fossa lesions rarely produce hydrocephalus. Patients' age, cyst location and size, and macrocephaly have all been related to the development of hydrocephalus. Some authors remark on the role played by hydrocephalus and hypothesize that some ACs would result from disturbed cerebrospinal fluid (CSF) dynamics. They also propose that ACs might represent a localized form of hydrocephalus. We also comment on hydrocephalus in relation to the diverse locations of ACs. Neuroendoscopic techniques have transformed previous ways of management as cystoperitoneal shunting and open fenestration.

CONCLUSIONS

ACs may be pathogenetically related with hydrocephalus, and conversely, ACs may cause hydrocephalus. In some patients, aberrant CSF dynamics seems to play a major role in the development of both cyst and hydrocephalus. Hydrocephalus and ACs may be treated exclusively with neuroendoscopic procedures, although some patients will still require CSF shunting. The ideal option seems to consist of choosing the method that offers the highest success with a single procedure for treating the hydrocephalus and the AC simultaneously.

A novel method for stereotactic, endoscope-assisted transtentorial placement of a shunt catheter into symptomatic posterior fossa cysts

OBJECT

Posterior fossa cysts are usually divided into Dandy-Walker malformations, arachnoid cysts, and isolated and/or trapped fourth ventricles. Shunt placement is a mainstay treatment for decompression of these fluid collections when their expansion becomes symptomatic. Although several techniques to drain symptomatic posterior fossa cysts have been described, each method carries its own advantages and disadvantages. This article describes an alternative technique.

METHODS

In 10 patients, the authors used an alternative technique involving stereotactic and endoscopic methods to place a catheter in symptomatic posterior fossa cysts across the tentorium. Discussion of these cases is included, along with a review of various approaches to shunt placement in this region and recommendations regarding the proposed technique.

RESULTS

No patient suffered intracranial hemorrhage related to the procedure and catheter implantation. All 3 patients who underwent placement of a new transtentorial cystoperitoneal shunt and a new ventriculoperitoneal shunt did not suffer any postoperative complication; a decrease in the size of their posterior fossa cysts was evident on CT scans obtained during the 1st postoperative day. Follow-up CT scans demonstrated either stable findings or further interval decrease in the size of their cysts. In 1 patient, the postoperative head CT demonstrated that the transtentorial catheter terminated posterior to the right parietal occipital region without entering the retrocerebellar cyst. This patient underwent a repeat operation for proximal shunt revision, resulting in an acceptable catheter implantation. The patient in Case 8 suffered from a shunt infection and subsequently underwent hardware removal and aqueductoplasty with stent placement. The patient in Case 9 demonstrated a slight increase in fourth ventricle size and was returned to the operating room. Exploration revealed a kink in the tubing connecting the distal limb of the Y connector to the valve. The Y connector was replaced with a T connector, and 1 week later, CT scans exhibited interval decompression of the ventricles. This patient later presented with cranial wound breakdown and an exposed shunt. His shunt hardware was removed and he was treated with antibiotics. He later underwent reimplantation of a lateral ventricular and transtentorial shunt and suffered no other complications during a 3-year follow-up period.

CONCLUSIONS

The introduction of endoscopic and stereotactic techniques has expanded the available treatment possibilities for posterior fossa cysts.

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

OBJECT

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.

METHODS

The authors performed a retrospective review of 79 consecutive patients (1993-2010) with surgically treated intracranial arachnoid cysts.

RESULTS

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.

CONCLUSIONS

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.

The effectiveness of ventriculocystocisternostomy for suprasellar arachnoid cysts

OBJECT

The aim of this study was to report the long-term outcomes of patients receiving endoscopic ventriculocystocisternostomy (VCC) for suprasellar arachnoid cysts (SACs), and to analyze all published reports on outcomes of ventriculocystostomy (VC) versus VCC to compare the effectiveness of the 2 techniques.

METHODS

Eleven consecutive patients with previously untreated SACs were surgically treated using endoscopic VCC. Another 2 patients were treated with VCC following ventriculoperitoneal shunt placement. Clinical imaging data were recorded. An analysis was performed of all published patient outcomes following endoscopic VC or VCC for an SAC.

RESULTS

Developmental delay and progressive macrocephaly were the most common preoperative symptoms. At a mean clinical follow-up interval of 63 months, 10 of 11 patients undergoing primary VCC did not require reoperation. An analysis of the literature suggests that VCC may be more effective than VC. Of the 44 reported patients that underwent VC as a first treatment, 7 (16%) required reoperation, and 7 (8%) of 86 patients who underwent VCC as a first treatment required reoperation. When VC or VCC was performed following a prior surgical procedure, 4 of 11 patients undergoing VC had a treatment failure requiring reoperation. In contrast, only 2 of the 17 reported cases of VCC following a prior procedure required further treatment. The difference in reoperation rates following either primary or secondary VC was significantly higher than following primary or secondary VCC (p = 0.04).

CONCLUSIONS

The authors conclude that VCC is an effective and durable treatment for symptomatic SACs in most cases.

Prevalence and natural history of arachnoid cysts in children

OBJECT

Arachnoid cysts are a frequent finding on intracranial imaging in children. The prevalence and natural history of these cysts are not well defined. The authors studied a large consecutive series of children undergoing MR imaging to better define both the MR imaging-demonstrated prevalence and behavior of these lesions over time.

METHODS

The authors reviewed a consecutive series of 11,738 patients who were 18 years of age or younger and had undergone brain MR imaging at a single institution during an 11-year period. In the patients in whom intracranial arachnoid cysts were identified, clinical and demographic information was recorded and imaging characteristics, such as cyst size and location, were evaluated. Prevalence data were analyzed using univariate and multivariate logistic regression, linear regression, and ANOVA. All patients with sufficient data (repeat MR imaging studies as well as repeated clinical evaluation over at least 5 months) for a natural history analysis were identified. This group was assessed for any change in symptoms or imaging appearance during the follow-up interval.

RESULTS

Three hundred nine arachnoid cysts (2.6% prevalence rate) were identified. There was an increased prevalence of arachnoid cysts in males (p < 0.000001). One hundred eleven patients met all criteria for inclusion in the natural history analysis. After a mean follow-up of 3.5 years, 11 arachnoid cysts increased in size, 13 decreased, and 87 remained stable. A younger age at presentation was significantly associated with cyst enlargement (p = 0.001) and the need for surgery (p = 0.05). No patient older than 4 years of age at the time of initial diagnosis had cyst enlargement, demonstrated new symptoms, or underwent surgical treatment.

CONCLUSIONS

Arachnoid cysts are a common incidental finding on intracranial imaging in pediatric patients. An older age at the time of presentation is associated with a lack of clinical or imaging changes over time.