Evolution of the management of hydrocephalus associated with acoustic neuroma

Analysis of Evolution of Hydrocephalus in Posterior Fossa Tumors and Validation Study of the Modified Canadian Preoperative Prediction Rule for Hydrocephalus in Children and Frankfurt Grading System for Prediction of Cerebrospinal Fluid Diversion in Adults with Posterior Fossa Tumors

OBJECTIVE

We sought to analyze the evolution of hydrocephalus and enumerate its predictive factors in posterior fossa tumors in children and adults. We also validated the modified Canadian Preoperative Prediction Rule for Hydrocephalus (mCPPRH) and Frankfurt grading systems as tools to predict cerebrospinal fluid (CSF) diversion in children and adults, respectively.

METHODS

A retrospective review of patients with posterior fossa tumors operated between 2012 and 2019 was performed. Clinical, radiologic, and operative data were obtained. Validation was performed for both scores via receiver operating characteristic (ROC) curves and evaluation of the area under the curve (AUC).

RESULTS

We included 116 children and 343 adults in the study. Of the adults, 141 patients had intraaxial tumors and 172 had extraaxial tumors. The insertion of external ventricular drain (EVD), its duration, papilledema was noted to have significant influence on the need for permanent CSF diversion (P < 0.05) in children. The ROC for mCPPRH score was 0.659 (0.501-0.816), Age- 0.496 (0.334-0.658) and Evans index- 0.788 (0.654-0.922). In adults- Intraaxial tumours Age, Frankfurt score, duration of EVD, Diagnosis, Extent of resection and periventricular capping significant predictors and ROC age AUC 0.300 (0.193-0.407), Evans index 0.939 (0.888-0.990), and Frankfurt score 0.908 (0.853-0.964) (P < 0.05), whereas in extraaxial tumors Frankfurt grading, sex, duration of EVD, presence of perilesional edema and extent of resection (P < 0.05) ROC age AUC 0.439 (0.344-0.534), Evans index 0.941 (0.906-0.977), and Frankfurt score 0.847 (0.782-0.912).

CONCLUSIONS

This is the first external validation study for the 2 predictive systems in use. mCPPRH demonstrated poor predictive accuracy, and Frankfurt grading system demonstrated good accuracy. EVD insertion and its duration was significantly predictive of the need for permanent CSF diversion.

An integrative survival analysis and a systematic review of the cerebellopontine angle glioblastomas

Glioblastomas presenting topographically at the cerebellopontine angle (CPA) are exceedingly rare. Given the specific anatomical considerations and their rarity, overall survival (OS) and management are not discussed in detail. The authors performed an integrative survival analysis of CPA glioblastomas. A literature search of PubMed, Scopus, and Web of Science databases was performed per PRISMA guidelines. Patient data including demographics, clinical features, neuroimaging, management, follow-up, and OS were extracted. The mean age was 39 ± 26.2 years. The mean OS was 8.9 months. Kaplan-Meier log-rank test and univariate Cox proportional-hazards model identified hydrocephalus (log-rank, p = 0.034; HR 0.34; 95% CI 0.12-0.94; p = 0.038), chemotherapy (log-rank, p < 0.005; HR 5.66; 95% CI 1.53-20.88; p = 0.009), and radiotherapy (log-rank, p < 0.0001; HR 12.01; 95% CI 3.44-41.89; p < 0.001) as factors influencing OS. Hydrocephalus (HR 3.57; 95% CI 1.07-11.1; p = 0.038) and no adjuvant radiotherapy (HR 0.12; 95% CI 0.02-0.59; p < 0.01) remained prognostic on multivariable analysis with fourfold and twofold higher risk for the time-related onset of death, respectively. This should be considered when assessing the risk-to-benefit ratio for patients undergoing surgery for CPA glioblastoma.

Association of Patient Frailty With Vestibular Schwannoma Resection Outcomes and Machine Learning Development of a Vestibular Schwannoma Risk Stratification Score

BACKGROUND

Patient frailty is predictive of higher neurosurgical morbidity and mortality. However, existing frailty measures are hindered by lack of specificity to neurosurgery.

OBJECTIVE

To analyze the association between 3 risk stratification scores and outcomes for nationwide vestibular schwannoma (VS) resection admissions and develop a custom VS risk stratification score.

METHODS

We identified all VS resection admissions in the National Inpatient Sample (2002-2017). Three risk stratification scores were analyzed: modified Frailty Index-5, modified Frailty Index-11(mFI-11), and Charlson Comorbidity Index (CCI). Survey-weighted multivariate regression evaluated associations between frailty and inpatient outcomes, adjusting for patient demographics, hospital characteristics, and disease severity. Subsequently, we used k-fold cross validation and Akaike Information Criterion-based model selection to create a custom risk stratification score.

RESULTS

We analyzed 32 465 VS resection admissions. High frailty, as identified by the mFI-11 (odds ratio [OR] = 1.27, P = .021) and CCI (OR = 1.72, P < .001), predicted higher odds of perioperative complications. All 3 scores were also associated with lower routine discharge rates and elevated length of stay (LOS) and costs (all P < .05). Our custom VS-5 score (https://skullbaseresearch.shinyapps.io/vs-5_calculator/) featured 5 variables (age ≥60 years, hydrocephalus, preoperative cranial nerve palsies, diabetes mellitus, and hypertension) and was predictive of higher mortality (OR = 6.40, P = .001), decreased routine hospital discharge (OR = 0.28, P < .001), and elevated complications (OR = 1.59, P < .001), LOS (+48%, P < .001), and costs (+23%, P = .001). The VS-5 outperformed the modified Frailty Index-5, mFI-11, and CCI in predicting routine discharge (all P < .001), including in a pseudoprospective cohort (2018-2019) of 3885 admissions.

CONCLUSION

Patient frailty predicted poorer inpatient outcomes after VS surgery. Our custom VS-5 score outperformed earlier risk stratification scores.

Characteristics and management of hydrocephalus in adult patients with cerebellar glioblastoma: lessons from a French nationwide series of 118 cases

The characteristics of hydrocephalus associated with cerebellar glioblastoma (cGB) remain poorly known. The objectives were to describe the occurence of hydrocephalus in a French nationwide series of adult patients with cGB, to identify the characteristics associated with hydrocephalus and to analyze the outcomes associated with the different surgical strategies, in order to propose practical guidelines. Consecutive cases of adult cGB patients prospectively recorded into the French Brain Tumor Database between 2003 and 2017 were screened. Diagnosis was confirmed by a centralized neuropathological review. Among 118 patients with cGB (mean age 55.9 years), 49 patients (41.5%) presented with pre-operative hydrocephalus. Thirteen patients (11.0%) developed acute (n=7) or delayed (n=6) hydrocephalus postoperatively. Compared to patients without hydrocephalus at admission, patients with hydrocephalus were younger (52.0 years vs 58.6 years, p=0.03) and underwent more frequently tumor resection (93.9% vs 73.9%, p=0.006). A total of 40 cerebrospinal-fluid diversion procedures were performed, including 18 endoscopic third ventriculostomies, 12 ventriculoperitoneal shunts and 10 external ventricular drains. The different cerebrospinal-fluid diversion options had comparable functional results and complication rates. Among the 89 patients surgically managed for cGB without prior cerebrospinal-fluid diversion, 7 (7.9%) were long-term shunt-dependant. Hydrocephalus is frequent in patients with cGB and has to be carefully managed in order not to interfere with adjuvant oncological treatments. In case of symptomatic hydrocephalus, a cerebrospinal-fluid diversion is mandatory, especially if surgical resection is not feasible. In case of asymptomatic hydrocephalus, a cerebrospinal-fluid diversion has to be discussed only if surgical resection is not feasible.

The role of external ventricular drainage for the management of posterior cranial fossa tumours: a systematic review

Posterior cranial fossa tumours frequently develop hydrocephalus as first presentation in up to 80% of paediatric patients and 21.4% of adults, although it resolves after tumour removal in 70-90% and 96%, respectively. New onset hydrocephalus is reported in about 2.1% of adult and 10-40% of paediatric patients after posterior fossa surgery. There is no consensus concerning prophylactic external ventricular drainage (EVD) placement that is frequently used before posterior fossa lesion removal, as well in those cases without clear evidence of hydrocephalus. The aim of the study was to define the most correct management for patients who undergo posterior fossa tumour surgery, thus identifying cohorts of patients who are at risk of persistent hydrocephalus prior to surgery. A systematic review of literature has been performed, following PRISMA guidelines. Most of the studies reported CSF shunt only in the presence of hydrocephalus, whereas only a few authors suggested its prophylactic use in the absence of signs of ventricular dilatation. Predictive factors for postoperative hydrocephalus has been identified, including young age (< 3 years), severe symptomatic hydrocephalus at presentation, EVD placement before surgery, FOHR index > 0.46 and Evans index > 0.4, pseudomeningocele, CSF leak and infection. The use of pre-resection CSF shunt in case of signs and symptoms of hydrocephalus is mandatory, although it resolves in the majority of cases. As reported by several studies included in the present review, we suggest CSF shunt also in case of asymptomatic hydrocephalus, whereas it is not indicated without evidence of ventricular dilatation.

Characteristics and management of hydrocephalus associated with vestibular schwannomas: a systematic review

Hydrocephalus (HC) can be associated with vestibular schwannoma (VS) at presentation. Although spontaneous resolution of HC after VS removal is reported, first-line treatment is varied including preoperative ventriculoperitoneal (VP) shunt, external ventricular drainage (EVD), or lumbar drainage (LD). We performed a systematic review to clarify optimal management of HC associated with VS at presentation, as well as characteristics of patients with initial and persistent HC after VS removal, and prevalence of HC associated with VS. Fourteen studies were included. Patients were grouped according to the timing of HC treatment. The overall rate of VP shunts was 19.4%. Among patients who received VS removal as first-line treatment, 6.9% underwent permanent shunts. In a subgroup of 132 patients (studies with no-aggregate data), t test analysis for mean tumor size (P = 0.02) and mean CSF protein level (P < 0.001) demonstrated statistically significant differences between patients with resolved HC (3.48 cm and 201 mg/dL) and patients with persistent HC (2.46 cm and 76.8 mg/dL) after VS resection. Transient treatment of HC using EVD or LD further resolved the HC in 87.5% and 82.9% of patients, respectively, before and after VS removal. The overall prevalence of HC associated with VS in a population of 2336 patients was 9.3%. Schwannoma removal as first-line treatment is justified by its low rate of persistent HC requiring VP shunt (roughly 7%). Patients with smaller VS and lower CSF proteins present higher risk of persistent HC after schwannoma removal. Temporary treatment of HC contributes to its resolution, both before and after VS removal.

Hydrocephalus Associated with Large Vestibular Schwannoma: Management Options and Factors Predicting Requirement of Cerebrospinal Fluid Diversion after Primary Surgery

Objective:

Obstructive hydrocephalus (HCP) related to vestibular schwannoma occurs in large tumors compressing the fourth ventricle. Symptoms related to HCP are expected to alleviate after resection of the tumor and decompression of the cerebrospinal fluid (CSF) pathways. However, some patients may require permanent cerebrospinal diversion even after surgery due to persistent HCP. In this study, the authors try to find out the factors associated with the requirement of CSF diversion after vestibular schwannoma surgery in cases of persistent HCP.

Materials and Methods:

This was a retrospective study involving 193 cases of vestibular schwannoma operated between 2010 and 2013 in our institute. Cases that underwent ventriculoperitoneal (VP) shunts before surgery were compared to cases which were operated directly. In cases where vestibular schwannomas were operated without prior VP shunts, factors which were associated with persistent postoperative HCP were analyzed.

Results:

Comparing the group who underwent direct surgery to the group who underwent VP shunt before definitive vestibular schwannoma surgery, the facial nerve preservation rates and surgical morbidity rates were comparable. In cases who underwent direct surgery, 10 out of 75 patients required postoperative permanent CSF diversion. Older age, male gender, duration of symptoms, larger tumor size, solid lesions, severe HCP, and clinical features of HCP were associated with postoperative requirement of CSF diversion but were not statistically significant. The most significant factor that correlated with the need for additional HCP treatment was the presence of postoperative hematoma of volume >10cc.

Conclusions:

Primary tumor removal is the optimal treatment for vestibular schwannoma associated with HCP. Postoperative hematoma may warrant close observation as these patients are at an increased risk of persistence of HCP.

Frequency and treatment of hydrocephalus prior to and after posterior fossa tumor surgery in adult patients

BACKGROUND

There is paucity of information about the frequency of hydrocephalus prior to and after posterior fossa tumor surgery in adult patients and about the best way it should be managed. The present study was conducted to determine the frequency of hydrocephalus prior to and after posterior fossa tumor surgery in adult patients as well as the value of an endoscopic third ventriculostomy (ETV) prior to posterior fossa tumor surgery with regard to the rate of perioperative complications and persistent hydrocephalus.

METHODS

A single-institution retrospective chart review of all posterior fossa tumor surgeries of our department in a 10-year period (2005 to 2014) has been done.

RESULTS

Fifty-two of 243 adult patients with posterior fossa tumors presented with hydrocephalus at the time of admission prior to tumor surgery. 39/52 received early tumor surgery, 11/52 an ETV prior to tumor surgery and in 2/52 an external ventricular drainage (EVD) was inserted prior to tumor surgery. 3/52 patients required a permanent cerebrospinal fluid (CSF) diverting procedure for persistent hydrocephalus after tumor removal. One hundred ninety-one patients did not demonstrate a hydrocephalus before surgical treatment and four of them developed a post-resection hydrocephalus.

CONCLUSION

The frequency of hydrocephalus prior to posterior fossa tumor surgery in adult patients is 21.4% and therefore much lower than in respective reports of pediatric patients. The risk of persistent hydrocephalus and newly developed hydrocephalus after tumor surgery was very low, too (5.7 and 2.1%, respectively). An ETV is not justified in every adult patient prior to posterior fossa tumor surgery.

Predictive Factors of Unfavorable Events After Gamma Knife Radiosurgery for Vestibular Schwannoma

OBJECTIVE

Gamma Knife radiosurgery (GKS) for the treatment of vestibular schwannoma (VS) introduces risks to the facial nerve and auditory perception and may involve post-treatment complications such as pseudoprogression, hydrocephalus, and other cranial neuropathies. This study of patients with VS who underwent GKS investigated radiosurgical results, focusing on post-treatment complications and identifying the factors that predict such complications.

METHODS

We undertook a retrospective review of all VS patients treated with the Perfexion Leksell Gamma Knife between November 2007 and October 2010 at our institution. Patients who underwent at least 12 months of clinical and radiologic assessments before and after GKS were included.

RESULTS

All 235 patients were included in the analyses reported here. The 5-year serviceable hearing and facial nerve preservation values were 73.9% and 94.3%, respectively. Following GKS, 43 patients (18.30%) showed pseudoprogression, 15 (6.38%) exhibited hydrocephalus, 22 (9.36%) showed trigeminal neuropathy, 14 (5.96%) showed vertigo, and 25 (10.64%) showed facial myokymia. According to multivariate analysis, solid tumor nature was significantly associated with pseudoprogression and patient age was significantly associated with hydrocephalus. Patients receiving margin doses ≥13 Gy had a significantly higher probability of loss of serviceable hearing. Patients with smaller tumors had a trigeminal nerve preservation rate comparable with patients harboring larger tumors. Patients receiving margin doses <13 Gy or older patients had a significantly higher probability of vestibular nerve dysfunction.

CONCLUSIONS

Further prospective studies should be designed to provide further insight into the exact relationship between the predictive factors we investigated and post-treatment complications.

Vascular hyperpermeability as a hallmark of phacomatoses: is the etiology angiogenesis comparable with mechanisms seen in inflammatory pathways? Part I: historical observations and clinical perspectives on the etiology of increased CSF protein levels, CSF clotting, and communicating hydrocephalus: a comprehensive review

Phacomatoses are a special group of familial hamartomatous syndromes with unique neuro-cutaneous manifestations as well as disease characteristic tumors. Neurofibromatosis 2 (NF2) and tuberous sclerosis complex (TSC) are representatives of this family. Vestibular schwannoma (VS) and subependymal giant cell tumor (SGCT) are two of the most common intracranial tumors associated with NF2 and TSC, respectively. These tumors can present with obstructive hydrocephalus due to their location adjacent to or in the ventricles. However, both tumors are also known to have a unique association with an elevated protein concentration in the cerebrospinal fluid (CSF), sometimes in association with non-obstructive (communicating) hydrocephalus (HCP), the causality of which has been unclear. Furthermore, SGCTs have repeatedly been shown to have a predisposition for CSF clotting, causing debilitating obstructions and recurrent malfunctions in shunted patients. However, the exact relation between high protein levels and spontaneous clotting of the CSF is not clear, nor is the mechanism understood by which CSF may clot in SGCTs. Elevated protein levels in the CSF are thought to be caused by increased vascular permeability and dysregulation of the blood-brain barrier. The two presumed underlying pathophysiologic mechanisms for that, in the context of tumorigenesis, are angiogenesis and inflammation. Both mechanisms are correlated to the Pi3K/Akt/mTOR pathway which is a major tumorigenesis pathway in nearly all phacomatoses. In this review, we discuss the influence of angiogenesis and inflammation on vascular permeability in VSs and SGCTs at the phenotypic level as well as their possible genetic and molecular determinants. Part I describes the historical perspectives and clinical aspects of the relationship between vascular permeability, abnormal CSF protein levels, clotting of the CSF, and communicating HCP. Part II describes different cellular and molecular pathways involved in angiogenesis and inflammation in these two tumors and the correlation between inflammation and coagulation. Interestingly, while increased angiogenesis can be observed in both VS and SGCT, inflammatory processes seem more prominent in SGCT. Both pathologies are characterized by different subgroups of tumor-associated macrophages (TAM): the pro-inflammatory, M1 type is predominating in SGCTs while pro-angiogenetic, M2 type is predominating in VSs. We suggest that lack of NF2 protein in VS and lack of TSC1/2 proteins in SGCT determine this fundamental difference between the two tumor types, by defining the predominant TAM type. Since inflammatory reactions and coagulation processes are tightly connected, a "pro-inflammatory state" of SGCT can be used to explain the observed associated enhanced CSF clotting process. These distinct cellular and molecular differences may have direct therapeutic implications on tumors that are unique to certain phacomatoses or those with similar genetics.

Communicating Hydrocephalus Associated with Small- to Medium-Sized Vestibular Schwannomas: Clinical Significance of the Tumor Apparent Diffusion Coefficient Map

BACKGROUND

The etiology of hydrocephalus associated with the small- to medium-sized vestibular schwannomas is still controversial. We investigated tumor-specific factors related to the association of hydrocephalus with small- to medium-sized vestibular schwannomas.

METHODS

Among the 77 patients with vestibular schwannoma smaller than 30 mm, 9 patients demonstrated associated communicating hydrocephalus. Patient medical records, radiologic data, and histopathologic specimens were reviewed retrospectively. The age of the patients, and size, mean apparent diffusion coefficient (ADC) value, and histologic features of the tumors were compared with those of patients without hydrocephalus.

RESULTS

The symptoms related to hydrocephalus improved in all patients after tumor removal. Both the mean size and ADC values exhibited a statistically significant difference between the tumors with and without hydrocephalus (P < 0.01).

CONCLUSIONS

The size and ADC value of the tumor were significantly related to the association with hydrocephalus. The increased tumor ADC value was considered to be the result of degenerative change and suggested the involvement of protein sloughing in the etiology of the associated hydrocephalus.

Sudden Death Due to Vestibular Schwannoma: Caution in Emergent Management

OBJECTIVE

To enhance understanding of the possible dangers of large vestibular schwannomas and their potential to cause sudden death through rare situations such as brain herniation precipitated by cerebrospinal fluid pressure shifts.

PATIENT

An otherwise healthy 32-year-old woman with a magnetic resonance imaging demonstrating a cystic cerebellopontine angle mass, presumptive for vestibular schwannoma, experienced sudden onset of headaches, nausea, and vomiting.

INTERVENTION

The patient was admitted to the intensive care unit, started on anticonvulsants, investigated with serial computed tomography (CT) scans, and then elective intubation and ventriculostomy when her condition worsened.

MAIN OUTCOME MEASURE(S)

Clinical and radiological findings, as well as outcome of interventions.

RESULTS

In the first hours of admission, the patient underwent serial CT scans that demonstrated fourth ventricle compression and hydrocephalus. When the patient's condition worsened, elective intubation was undertaken and an external ventricular drain was inserted. Very high intracranial pressures were noted despite cerebrospinal fluid drainage. Postoperative CT and magnetic resonance imaging demonstrated ascending transtentorial and tonsillar herniation as well as scattered cortical infarcts. Brain death was determined and care was withdrawn 5 days later.

CONCLUSION

This is a very rare patient report of sudden death caused by a large vestibular schwannoma despite assertive emergent management. There was no intratumoral or intracranial haemorrhage. Brain death was likely a result of ascending transtentorial herniation that can occur with large posterior fossa tumors and be exacerbated by cerebrospinal fluid shifts after ventriculostomy.

Communicating Hydrocephalus Associated with Intracranial Schwannoma Treated by Gamma Knife Radiosurgery

OBJECTIVE

Gamma knife radiosurgery (GKRS) has been established as an effective and safe treatment for intracranial schwannoma. However, serious complications can occur after GKRS, including hydrocephalus. The pathophysiology and risk factors of this disorder are not yet fully understood. The objective of the study was to assess potential risk factors for hydrocephalus after GKRS.

METHODS

We retrospectively reviewed the medical radiosurgical records of 244 patients who underwent GKRS to treat intracranial schwannoma. The following parameters were analyzed as potential risk factors for hydrocephalus after GKRS: age, sex, target volume, irradiation dose, prior tumor resection, treatment technique, and tumor enhancement pattern. The tumor enhancement pattern was divided into 2 groups: group A (homogeneous enhancement) and group B (heterogeneous or rim enhancement).

RESULTS

Of the 244 patients, 14 of them (5.7%) developed communicating hydrocephalus. Communicating hydrocephalus occurred within 2 years after GKRS in most patients (92.8%). No significant association was observed between any of the parameters investigated and the development of hydrocephalus, with the exception of tumor enhancement pattern. Group B exhibited a statistically significant difference by univariate analysis (P = 0.002); this difference was also significant by multivariate analysis (P = 0.006).

CONCLUSION

Because hydrocephalus is curable, patients should be closely monitored for the development of this disorder after GKRS. In particular, patients with intracranial schwannomas with irregular enhancement patterns or cysts should be meticulously observed.

Hydrocephalus associated with vestibular schwannomas: perioperative changes in cerebrospinal fluid

BACKGROUND

Cerebrospinal fluid (CSF) protein levels are known to increase in patients with vestibular schwannomas (VS) with concomitant hydrocephalus, however the only information available on perioperative changes in CSF in these patients comes from case reports. Here, we investigated the relation between CSF protein and hydrocephalus in a large series of patients undergoing resection of VS.

METHOD

We classified 376 patients undergoing resection for VS at our institute into two groups, namely VS and no hydrocephalus (control, n = 319) and VS with concomitant hydrocephalus (n = 57), and compared clinical parameters. Among the 57 patients diagnosed with hydrocephalus, hydrocephalus status was examined by lumbar puncture in 20 patients with communicative hydrocephalus, and pre- and postoperative scores in CSF properties were compared.

RESULTS

Patients in the hydrocephalus group were significantly older than those in the control group (mean, 55.8 vs. 43.8 years), and had a longer disease duration (median, 76 vs. 12 months), larger tumors (median, 15.6 vs. 5.5 ml), and a higher protein concentration in CSF (median, 147.3 vs. 65.1 mg/dl). Perioperative CSF samples of hydrocephalus patients showed a significantly decrease in cerebrospinal pressure after tumor removal (median, -75mmH2O), followed by a decrease in CSF protein (median, -74.5 mg/dl). No patients required the placement of a shunt.

CONCLUSIONS

Extended disease duration and elevated CSF protein secondary to the presence of a tumor contribute to the occurrence of hydrocephalus. Primary maximal tumor removal for VS with coexisting hydrocephalus avoids an unnecessary shunt.

Communicating hydrocephalus and vestibular schwannomas: etiology, treatment, and long-term follow-up

Background Large vestibular schwannomas (VSs) can cause hydrocephalus by obstructing the fourth ventricle. Little is known about the communicating hydrocephalus that is seen with a smaller VS. Methods The clinicopathological findings and follow up of three patients with communicating hydrocephalus associated with a small VS are presented. Results Four patients aged 40 to 66 years (mean: 57.7) presented with ataxia, dementia, and urinary incontinence. The VS were 2.0 to 2.4 cm. The cerebrospinal fluid (CSF) protein was elevated in three patients in whom it was measured (1.7 to 6 times normal). The VS was resected in two patients. All of the patients required ventriculoperitoneal shunting (VPS). All of the patients were asymptomatic or improved at follow-up at 9 months to 13 years. Conclusion Communicating hydrocephalus associated with a VS can occur in younger patients than was previously thought. An elevated CSF protein appears to be important, but other factors may be involved. A shunting procedure is often required to relieve the symptoms of hydrocephalus even if the tumor is resected. Possible etiological causes of communicating hydrocephalus in patients with a small VS are discussed.

Risk factors and tumor response associated with hydrocephalus after gamma knife radiosurgery for vestibular schwannoma

BACKGROUND

This study was designed to investigate the clinical characteristics and risk factors of hydrocephalus after gamma knife radiosurgery (GKRS) for vestibular schwannoma.

METHODS

The authors retrospectively reviewed clinical and neuroimaging findings of 221 patients who underwent GKRS for newly diagnosed vestibular schwannoma. Mean patient age was 54.1 years (range 7-83 years), mean tumor volume was 3,010.4 mm(3) (range 34.7 to 14,300 mm(3)), mean marginal dose was 12.5 Gy (range 11 to 15 Gy), and mean follow-up duration was 31.9 months (range 1 to 107.6 months).

RESULTS

Surgical intervention for cerebrospinal fluid (CSF) diversion after GKRS was necessary in 11 (5 %) of the patients. Median time between GKRS and ventriculoperitoneal (VP) shunt placement was 15.5 months (range 1.8-37.8 months). These 11 patients showed female predominance (11 females) and mean tumor volume was significantly larger than in the other without hydrocephalus (6,509 vs. 2,726 mm(3); p < 0.01). Decreases in tumor enhancement and swelling were observed in all 221 patients, and CSF protein was found to be elevated in five of nine patients with available data at the time of the shunt procedure. Hydrocephalic symptoms improved after VP shunt and tumor sizes further decreased at last follow-up in all patients.

CONCLUSIONS

Hydrocephalus after radiosurgery may co-occur with a temporary change of tumor volume after radiation treatment. Therefore, hydrocephalus should be kept in mind during the time of tumor volume transition. Furthermore, the authors suggest that frequent patient monitoring for hydrocephalus be maintained for up to 3-4 years after GKRS.

Hydrocephalus associated with vestibular schwannomas: management options and factors predicting the outcome

Object

The current, generally accepted optimal management for hydrocephalus related to vestibular schwannomas (VSs) is primary tumor removal, with further treatment reserved only for patients who remain symptomatic. Previous studies have shown, however, that this management can lead to an increase in surgery-related complications. In this study, the authors evaluated their experience with the treatment of such patients, with the aim of identifying the following: 1) the parameters correlating to the need for specific hydrocephalus treatment following VS surgery; and 2) patients at risk for developing hydrocephalus-related complications.

Methods

This was a retrospective study of a 400-patient series. The complication rates and outcomes following primary hydrocephalus treatment versus primary VS removal were compared. Patients undergoing primary tumor removal were further subdivided on the basis of the need for subsequent hydrocephalus treatment. The 3 categories of parameters tested for correlation with the need for such subsequent treatment as well as with heightened risk for developing complications were patient-, tumor-, and hydrocephalus-related.

Results

Of the entire series, 53 patients presented with hydrocephalus. Forty-eight of 53 patients underwent primary VS surgery, of whom 42 (87.5%) did not require additional hydrocephalus treatment. Of the 6 patients who did require additional hydrocephalus treatment, only 3 ultimately required a VP shunt. Factors correlating to the need of hydrocephalus treatment after VS removal were large tumor size, irregular tumor surface, and severe preoperative hydrocephalus. Patients with a longer symptom duration prior to surgery, those with polycyclic tumors, or with inhomogeneous VS, were at heightened risk for the development of CSF leaks. The general and functional outcome of surgery showed no correlation to the presence of preoperative hydrocephalus.

Conclusions

Primary tumor removal is the optimum management of disease in patients with VS with associated hydrocephalus; it leads to resolution of the hydrocephalus in the majority of cases, and the outcome is similar to that of patients without hydrocephalus. Certain factors may aid in identifying patients at risk for developing persistent hydrocephalus as well as those at risk for CSF leaks.

Long-term outcomes of Gamma Knife radiosurgery in patients with vestibular schwannomas

Object

The authors sought to determine the long-term tumor control and side effects of Gamma Knife radiosurgery (GKRS) in patients with vestibular schwannomas (VS).

Methods

One hundred seventeen patients with VS underwent GKRS between January 1997 and February 2003. At the time of analysis, at least 5 years had passed since GKRS in all patients. The mean patient age was 60.9 years. The mean maximal tumor diameter was 1.77 ± 0.71 cm. The mean tumor volume was 1.95 ± 2.42 ml. Eighty-two percent of lesions received 1300 cGy and 14% received 1200 cGy. The median dose homogeneity ratio was 1.97 and the median dose conformality ratio was 1.78. Follow-up included MR imaging or CT scanning approximately every 6–12 months. Rates of progression to surgery were calculated using the Kaplan-Meier method.

Results

Of the 117 patients in whom data were analyzed, 103 had follow-up MR or CT images and 14 patients were lost to follow-up. Fifty-three percent of patients had stable tumors and 37.9% had a radiographically documented response. Imaging-documented tumor progression was present in 8 patients (7.8%), but in 3 of these the lesion eventually stabilized. Only 5 patients required a neurosurgical intervention. The estimated 1-, 3-, and 5-year rates of progression to surgery were 1, 4.6, and 8.9%, respectively. One patient (1%) developed trigeminal neuropathy, 4 patients (5%) developed permanent facial neuropathy, 3 patients (4%) reported vertigo, and 7 patients (18%) had new gait imbalance following GKRS.

Conclusions

Gamma Knife radiosurgery results in excellent local control rates with minimal toxicity for patients with VS. The authors recommend standardized follow-up to gain a better understanding of the long-term effects of GKRS.

Communicating hydrocephalus after gamma knife radiosurgery for vestibular schwannoma: an MR imaging study

Vestibular schwannomas are common, and gamma knife radiosurgery is a treatment option of symptomatic tumors. Hydrocephalus may be a complication of gamma knife treatment of vestibular schwannoma, though the cause-and-effect relationship can be debated because tumors can cause hydrocephalus without treatment. We present an MR imaging study of an unusual case of communicating hydrocephalus after gamma knife radiosurgery of a vestibular schwannoma in which the timeline of events strongly suggests that gamma knife played a contributory role in the development of hydrocephalus. We discuss risk factors for the development of hydrocephalus after radiation therapy and the role of MR CSF cine-flow study in the evaluation of treatment options for hydrocephalus in this setting.

Normal pressure hydrocephalus after gamma knife radiosurgery for cerebellopontine angle meningioma

There are no reports of hydrocephalus following radiosurgery for a meningioma. We report on a case where gamma knife therapy for a 4 cm diameter right cerebellopontine meningioma accelerated hydrocephalus three months post treatment. Examination of the cerebrospinal fluid (CSF) revealed a high protein level and thus, CSF malabsorption and CSF obstruction might have occurred after the radio surgery. It is important to consider this pathology, and the need for long term follow up.

ETIOPATHOLOGICAL FACTORS RELATED TO HYDROCEPHALUS ASSOCIATED WITH VESTIBULAR SCHWANNOMA

OBJECTIVE

We retrospectively analyzed various clinical factors to determine whether or not these factors are etiopathologically related to the development of hydrocephalus in patients with vestibular schwannomas.

METHODS

There were 68 patients (29 men, 39 women) in this study who underwent resection of a vestibular schwannoma. The age at the time of surgery ranged from 19 to 76 years (mean age, 51.4 yr). The maximum diameter of the tumor in the cerebellopontine cistern ranged from 0 (localized within the internal auditory canal) to 56 mm (mean, 32.0 ± 12.9 mm). Cerebrospinal fluid (CSF) protein concentration in the cerebellomedullary cistern was measured intraoperatively in all patients.

RESULTS

Sixteen (23.5%) of the 68 patients exhibited radiographic evidence of hydrocephalus. Univariate analysis of various factors revealed that both tumor size and CSF protein concentration were positively related to development of hydrocephalus (P &lt; 0.05 and P &lt; 0.01, respectively). However, in multiple logistic regression analysis, only the CSF protein concentration was predictive for development of hydrocephalus (P = 0.022). There was a trend toward increased CSF protein concentration in patients with a large tumor (≥40 mm) compared with those with a small tumor (&lt;40 mm) (P = 0.06).

CONCLUSION

A high CSF protein concentration in fluid from the cerebellomedullary cistern is one of the most important factors contributing to hydrocephalus associated with vestibular schwannoma. It is important to judge whether or not any further treatment is required for hydrocephalus, in addition to tumor resection, especially in patients with communicating hydrocephalus.

The role of endoscopic third ventriculostomy in the management of hydrocephalus associated with cerebellopontine angle tumours

BACKGROUND

Progressive hydrocephalus secondary to cerebellopontine angle tumours has been traditionally managed with ventriculo-peritoneal shunting. Endoscopic third ventriculostomy provides an alternative treatment option and the success rate in this patient group has not previously been reported.

METHODS

We report a retrospective series of 11 patients with cerebello-pontine angle tumours who presented with symptomatic hydrocephalus, or developed hydrocephalus following radiosurgery, who underwent endoscopic third ventriculostomy.

RESULTS

Seven patients (63.6%) remain shunt free. There were no complications following endoscopy in any patient. Where the ventriculostomy failed there was no additional morbidity.

CONCLUSIONS

Endoscopic third ventriculostomy is a low morbidity procedure, which avoids the inherent problems of shunts, particularly infection and should be considered for patients with hydrocephalus and cerebello-pontine angle tumours.

Linear accelerator radiosurgery for vestibular schwannoma: measuring tumor volume changes on serial three-dimensional spoiled gradient-echo magnetic resonance images

OBJECT

The authors report on a series of 46 patients harboring vestibular schwannomas (VSs) treated using linear accelerator (LINAC) radiosurgery and an analysis of serial magnetic resonance (MR) imaging data, specifically the changes in tumor volume.

METHODS

Fifty-three consecutive patients underwent LINAC radiosurgery for VS between 1993 and 2002. Seven of these patients were lost to follow up. Three-dimensional (3D) spoiled gradient-echo (SPGR) MR imaging was performed at 3- to 4-month intervals after radiosurgery. Tumor volume was measured on Gd-enhanced MR images of each slice. The median duration of follow-up MR imaging studies was 56.5 months (range 12-120 months). Follow-up imaging studies were conducted for longer than 1 year in 42 of 53 patients. Tumor volume changes were categorized into four types: enlargement (eight lesions [19%]), no change (two lesions [4.8%]), transient enlargement followed by shrinkage (19 lesions [45.2%]), and direct shrinkage (13 lesions [31%]). Two cases (4.8%) with twice the initial tumor volume required repeated radiosurgery. All cases of transient enlargement had subsequent shrinkage within 2 years after radiosurgery. Nine (21.4%) of 42 patients demonstrated ventricular enlargement on MR images obtained after radiosurgery. Three patients (7.1%) required placement of a ventriculoperitoneal shunt because of symptomatic hydrocephalus, and another four cases (9.5%) spontaneously resolved.

CONCLUSIONS

Volume measurement on 3D-SPGR MR imaging was a suitable method to assess tumor changes. Volume changes beyond twofold or continuous enlargement for longer than 2 years after radiosurgery are key criteria in rating the effects of radiation. Some cases of hydrocephalus after radiosurgery resolved spontaneously and their rates of occurrence were similar to the typical incidence of hydrocephalus associated with VS.

Prevalence of hydrocephalus in 157 patients with vestibular schwannoma

The purpose of this study was to determine the prevalence of hydrocephalus in patients with vestibular schwannoma. A second objective was to investigate possible etiologies for hydrocephalus in this population by attempting to correlate the incidence and severity of hydrocephalus with tumor volume and extent of fourth ventricular compression. The MRI examinations of 157 adult patients with vestibular schwannoma were retrospectively reviewed. Tumor size was quantified, and the presence of accompanying hydrocephalus was assessed, categorized as communicating type or non-communicating type and then rated as mild, moderate or severe (grades 1-3). Next, the degree of fourth ventricular distortion caused by tumor mass effect was evaluated and categorized as mild, moderate or severe (grades 1-3). Spearman's rank correlation coefficient was used to test the relationships between tumor volume and (1) the extent of fourth ventricular effacement and (2) severity of hydrocephalus. Hydrocephalus was present in 28/157 (18%) cases and was categorized as mild in 11/28 (39%), moderate in 15/28 (54%) and severe in 2/28 (7%). Communicating-type hydrocephalus was present in 17/28 (61%) and non-communicating type in 11/28 (39%). There was a positive correlation between the grade of non-communicating hydrocephalus and tumor volume (r=0.38; P<0.001) and between the severity of fourth ventricular compression and extent of hydrocephalus in this group(r=0.43; P<0.001). In patients who were classified as having communicating hydrocephalus, the correlation between tumor volume and the severity of hydrocephalus was poor (r=0.19; P=0.02) as was the correlation between the extent of fourth ventricular distortion and the severity of hydrocephalus (r=0.21; P<0.01). There is a high prevalence of hydrocephalus in patients with vestibular schwannoma. In a minority of cases non-communicating type hydrocephalus is present and the severity of hydrocephalus can be attributed to the affect of tumor volume on fourth ventricular compression. More commonly, however, communicating-type hydrocephalus exists and the correlation between the severity of fourth ventricular compression and extent of hydrocephalus is poor. Therefore, other etiologies for hydrocephalus, such as tumor protein sloughing, are likely relevant.

MRI analysis of hydrocephalus associated with acoustic neurinoma

We investigated the hydrocephalus in 24 patients associated with acoustic neurinoma. We found the high incidence of homo-lateral ventricular dilatation to the side of the acoustic neurinoma. Utilizing magnetic resonance imaging, the diameter of the tumor parallel to the pyramidal bone, diameter of the tumor perpendicular to the pyramidal bone, grade of the 4th ventricle deviation, and the shape of the tumor (round or oval) were analyzed. Ten (42%) of the 24 patients with acoustic neurinoma were found to have hydrocephalus. Seven (70%) of the 10 patients with hydrocephalus exhibited asymmetrical lateral ventricle dilatation: in all cases the lateral ventricle in the hemisphere homolateral to the acoustic neurinoma was larger than that of the contralateral side. The hydrocephalus was not related to the grade of the 4th ventricle deviation but rather to the diameter of the tumor parallel to the pyramidal bone (p < 0.01). The diameter of the tumor parallel to the pyramidal bone was also related to the asymmetrical lateral ventricular dilatation (p < 0.05).

Removal of large acoustic neurinomas (vestibular schwannomas) by the retrosigmoid approach with no mortality and minimal morbidity

OBJECTIVE

To evaluate the safety and efficacy of removing large acoustic neurinomas (> or =3 cm) by the retrosigmoid approach.

METHODS

Large acoustic neurinomas (mean (SD), 4.1 (0.6) cm) were removed from 50 consecutive patients by the retrosigmoid suboccipital approach while monitoring the facial nerve using a facial stimulator-monitor. Excision began with the large extrameatal portion of the tumour, followed by removal of the intrameatal tumour, and then removal of the residual tumour in the extrameatal region just outside the porus acusticus. The last pieces of tumour were removed by sharp dissection from the facial nerve bidirectionally, and resected cautiously in a piecemeal fashion.

RESULTS

There were no postoperative deaths. The tumour was removed completely in 43 of 50 patients (86%). The facial nerve was anatomically preserved in 92% of the patients and 84% had excellent facial nerve function (House-Brackmann grade 1/2). One patient recovered useful hearing after tumour removal. Cerebrospinal fluid leak occurred in 4%, but there were no cases of meningitis. All but two patients (96%) had a good functional outcome.

CONCLUSIONS

The method resulted in a high rate of functional facial nerve preservation, a low incidence of complications, and good functional outcomes, with no mortality and minimal morbidity. Very favourable results can be obtained using the retrosigmoid approach for the removal of large acoustic neurinomas.

Management of vestibular schwannoma by fractionated stereotactic radiotherapy and associated cerebrospinal fluid malabsorption

OBJECT

The goal of this study was to investigate outcomes in patients with vestibular schwannoma (VS) who were treated with fractionated stereotactic radiotherapy (SRT).

METHODS

One hundred one patients with VS were treated with fractionated SRT at a radiation level of 40 to 50 Gy administered in 20 to 25 fractions over a 5- to 6-week period. The median tumor size in these patients was 19 mm (range 3-40 mm), and 27 tumors were larger than 25 mm. Patients were consistently followed up using magnetic resonance imaging every 6 months for 5 years in principle. The median follow-up period was 45 months. The actuarial 5-year rate of tumor control (no growth > 2 mm and no requirement for salvage surgery) was 91.4% (95% confidence interval 85.2-97.6%). Three patients with progressive tumors underwent salvage tumor resection. The actuarial 5-year rate of useful hearing preservation (Gardner-Robertson Class I or II) was 71%. The observed complications of fractionated SRT included transient facial nerve palsy (4% of patients), trigeminal neuropathy (14% of patients), and balance disturbance (17% of patients). No new permanent facial weakness occurred after fractionated SRT. Eleven patients (11%) who had progressive communicating hydrocephalus (cerebrospinal fluid malabsorption) and no evidence of tumor growth after fractionated SRT required a shunt. The symptoms of this type of hydrocephalus were similar to those of normal-pressure hydrocephalus and occurred 4 to 20 months (median 12 months) after fractionated SRT. The mean size (+/- standard deviation) of tumors causing symptomatic hydrocephalus (25.5 +/- 7.8 mm) was significantly larger than that of other tumors (18.2 +/- 8.7 mm) (p = 0.011). Only four of the 72 patients with tumors smaller than 25 mm in maximum diameter received a shunt.

CONCLUSIONS

Fractionated SRT resulted in an excellent tumor control rate, even for relatively large tumors, and produced a high rate of hearing preservation that was comparable to the best results of single-fraction radiosurgery. The progression of communicating hydrocephalus should be monitored closely, particularly in patients harboring a large VS.

Clinical and neuroimaging characteristics of hydrocephalus associated with vestibular schwannoma

OBJECT

The clinical and neuroimaging characteristics of hydrocephalus associated with vestibular schwannoma were retrospectively analyzed to improve the perioperative management of the circulation of cerebrospinal fluid.

METHODS

A retrospective analysis was performed in 236 patients with unilateral vestibular schwannomas. The patients' ages ranged from 17 to 83 years (mean 53.6 +/- 13.2 years), and the diameters of the tumors the patients harbored ranged from 5 to 60 mm (mean 30.5 +/- 12.7 mm). Hydrocephalus was present before tumor resection in 33 patients (14%) and in six of these patients focal dilation of the sylvian fissures was noted. There was a significant correlation between the incidence of hydrocephalus and tumor size. The incidence of preoperative hydrocephalus among elderly patients (> or = 65 years of age) was 28.6% and that among younger patients (< 65 years of age) was 10.8%. Tumors in elderly patients with hydrocephalus (mean tumor diameter 32.8 +/- 11.7 mm; 12 patients) were significantly smaller than those in younger patients (mean tumor diameter 41.7 +/- 10.9 mm; 21 patients). Among patients with tumors smaller than 30 mm (114 patients), the incidence of hydrocephalus in elderly patients (25%) was 12-fold higher than that in younger patients (2.1%). Six patients with hydrocephalus who had focal dilation of the sylvian fissures were significantly older than 27 patients with hydrocephalus in whom there was no focal dilation. The dilated sylvian fissures collapsed in two patients spontaneously after tumor resection and in the other four patients after shunt placement.

CONCLUSIONS

The incidence of associated hydrocephalus is higher in older patients. Communicating hydrocephalus tends to occur in elderly patients. Enlargement of the ventricles with focal dilation of the sylvian fissures should not be misinterpreted as physiological brain atrophy.

[Analysis of cerebrospinal fluid related complications (hydrocephalus, fistula, pseudomeningocele and infection) following surgery for posterior fossa tumors]

INTRODUCTION

Hydrocephalus, cerebrospinal fluid (CSF) leak, pseudomeningocele and CSF infection are potential complications related to surgical treatment of posterior fossa tumors. The objectives of this study were to review the incidence of such complications and to identify contributing factors related to them.

MATERIAL AND METHODS

This study is based on a retrospective review of the medical records of 71 consecutive patients who underwent posterior fossa surgery for a tumor between the period January 1997 and December 2001. Postoperative hydrocephalus was defined as enlargement of the ventricles and the subsequent clinical worsening requiring surgical treatment. Criteria for CSF leakage were:observed leak of CSF through the wound, rhinorrhea or otorrhea. Pseudomeningocele was determined when there was a large epidural CSF collection diagnosed in the postoperative period or by magnetic resonance imaging performed at least three months after posterior fossa surgery. Finally, CSF infection was defined on clinical ground and positive biochemical examination, but not necessarily positive cultures.

RESULTS

The series included 84 operations for resection of posterior fossa tumors on 71 patients. There were CSF related complications in 31% (26/84)with the following detailed incidence: 9.5% (8/84) postoperative hydrocephalus; 14.3% (12/84) CSF leak, 7.1% (6/84) pseudomeningocele; 8.3% (7/84) CSF infection. The mortality rate is 5.9% (5/84). The tumor size was the only statistically significant factor associated with the occurrence of CSF related complications (mean 39.43 mm, SD 18.51 mm vs.29.80 mm, SD 14.12 mm, p=0.015). In the subgroup of patients, in which hydrocephalus was managed preoperatively, the election of an external ventricular drain vs.other strategies (subcutaneous reservoir, definite shunt or endoscopic third ventriculostomy) was associated with a higher occurrence of CSF related complications (p=0.006). The mortality rate was associated with age (mean 63.60 years, SD 5.86 years vs.49.18 years, SD 16.39 years; p=0.002). The occurrence of CSF related complications also influenced mortality (p=0.030), particularly postoperative hydrocephalus (p< 0.001). Inpatient hospital stay was longer in the subgroup of patients who developed CSF related complications (p=0.002).

CONCLUSIONS

Tumor size was the only factor associated with the development of CSF related complications after surgery for posterior fossa tumors. In the subgroup of patients in which hydrocephalus was surgically treated preoperatively, the election of an external ventricular drain compared to other surgical modalities was associated with a higher rate of CSF related complications. The development of such complications, particularly hydrocephalus, was related with mortality.

Management of hydrocephalus associated with vestibular schwannoma and other cerebellopontine angle tumors

OBJECTIVE

Hydrocephalus (HCP) resulting from cerebellopontine angle (CPA) tumors is not rare. This retrospective study was designed to investigate the incidence of HCP and the clinical presentations, management options, and outcomes of HCP in 284 patients with CPA tumors.

METHODS

A retrospective study of 284 consecutive patients with CPA tumors (mostly vestibular schwannomas) treated from 1985 to 1996 at Toronto Western Hospital managed by one surgical team consisting of a neurosurgeon and a neuro-otologist.

RESULTS

Thirty-nine patients (13.7%) had radiographic and/or clinical evidence of HCP, 37 preoperatively and 2 postoperatively. Tumor type distribution was 33 vestibular schwannomas, 5 meningiomas, and 1 cavernous hemangioma. Only five patients (12%) had obvious obstruction at the fourth ventricular level. In 36 patients (92%), symptoms were mostly chronic and mild, consistent with normal pressure hydrocephalus. Multivariate analysis confirmed the strong association of tumor size and incidence of HCP (P < .0001). Four patients underwent permanent shunting before microsurgical tumor excision, mainly because of florid symptoms of HCP. Microsurgical tumor excision without preoperative shunting was performed in 23 patients, 5 of whom required postoperative shunting in the first 2 months after tumor excision. Eighteen patients (78%) did not need shunts after tumor resection. With regard to tumor size, the postoperatively shunted group did not differ from the patients who had surgery but did not require shunt treatment (P < 0.50). The remaining 10 patients with preoperative HCP received shunts as the only treatment (3 patients), stereotactic radiosurgery (3 patients), or expectant management (4 patients). Two other patients without preoperative HCP developed postoperative HCP and required shunts. Postoperatively, we observed a significant (P < 0.001) increase in the incidence of pseudomeningocele and a nonsignificant (P < 0.1) increase in cerebrospinal fluid leaks (rhinorrhea and/or otorrhea) in patients without shunts as compared with postoperative patients without HCP. The patients were followed after any treatment for a mean of 3.2 years (range, 6 mo-10 yr). Follow-up in the patients who had surgery but did not require a shunt revealed a 61% decrease in clinical symptoms related to HCP and a 75% decrease in radiographic signs of HCP.

CONCLUSION

In the presence of HCP, operative resection of CPA tumors can be performed without permanent cerebrospinal fluid shunting. Precautionary measures to decrease the incidence of postoperative complications related to cerebrospinal fluid leak in patients with preoperative HCP include meticulous obliteration of any exposed air cells, including those around the internal auditory canal, accurate restoration of the dural barrier, and temporary lowering of intracranial pressure with a ventricular or lumbar drain. Patients with persistent symptomatic HCP after tumor excision should be treated with a ventriculoperitoneal shunt. Delaying this decision until the postoperative period is safe and avoids unnecessary shunting in the majority of patients.