Clinical and neuroimaging characteristics of hydrocephalus associated with vestibular schwannoma

How to position the patient? A meta-analysis of positioning in vestibular schwannoma surgery via the retrosigmoid approach

Objective

Patient positioning is a matter of ongoing debate in the surgical treatment of vestibular schwannoma (VS). Main endpoints of this discussion are preservation of facial nerve functioning, extent of resection, and complications. In this meta-analysis, we aim to investigate the impact of patient positioning on VS surgery via the retrosigmoid approach.

Methods

We searched for eligible comparative trials on PubMed, Cochrane library, and Web of Science. Positioning groups were compared regarding facial nerve outcome, extent of resection, postoperative hydrocephalus, postoperative CSF leaks, perioperative venous air embolism, and perioperative mortality. Two groups of positions were defined, and the following positions were allocated to those groups: (1) Semi-sitting and Sitting-position; (2) Lateral position, supine position with extensive head rotation, lateral oblique (=Fukushima/Three-quarter prone), and park-bench position.

Results

From 374 full-text screenings, 7 studies met the criteria and were included in our meta-analysis comprising 1640 patients. Our results demonstrate a significantly better long-term (≥6 months) outcome of the facial nerve after VS surgery in the semi-sitting positioning (OR: 1.49, 95%CI: 1.03-2.15, p = 0.03). Positioning did not influence the extent of resection, rate of postoperative CSF leaks, and the presence of a postoperative hydrocephalus. Overall incidence of venous air embolisms was significantly associated with VS surgery in sitting positioning (OR: 6.77, 95% CI: 3.66-12.54, p < 0.00001). Perioperative mortality was equal among both positioning groups.

Conclusion

Semi-sitting positioning seems to be associated with an improved facial nerve outcome after VS surgery via the retrosigmoid approach. Venous air embolisms are significantly more often observed among VS patients who underwent surgery in the sitting position, but the perioperative mortality is equal in both positioning groups. Both positioning groups are a safe procedure. Multicentric prospective randomized trials are needed to evaluate the risk-benefit ratio of each positioning in VS surgery via the retrosigmoid approach.

Hydrocephalus After Gamma Knife Radiosurgery for Vestibular Schwannoma: Favorable Outcomes After Shunt Placement

Recent literature has described the development of a normal pressure hydrocephalus after Gamma Knife radiosurgery in patients with vestibular schwannoma. However, there is minimal detail regarding the clinical course and extent of recovery in these patients following shunt placement. This information would help clinicians weigh the risks and benefits of shunt surgery. We describe the clinical course of two such patients who received shunt placement and made a significant recovery not only in gait but also in their cognitive function. Unlike idiopathic normal pressure hydrocephalus, where patients can have a limited recovery after shunt placement, patients with this form of secondary hydrocephalus appear to make a significant recovery following shunting. Due to the complexity of these patients, it is possible for clinicians to attribute normal pressure hydrocephalus symptoms to neurodegenerative disease or vestibular dysfunction. Thus, it is vital that clinicians have a high index of suspicion for hydrocephalus in vestibular schwannoma patients receiving Gamma Knife radiosurgery so that these patients can be treated early with shunt placement.

Hidden intra-meatal CSF fistula related to VP shunt as a cause for fatal tension pneumocephalus after vestibular schwannoma resection

BACKGROUND

Cerebrospinal fluid (CSF) leak through petrosal air cells is a known complication after drilling the posterior wall of the internal acoustic canal (IAC) for resection of vestibular schwannoma (VS). Whereas mild pneumocephalus is common after retrosigmoid craniotomy, tension pneumocephalus has been rarely documented.

OBJECTIVE

To testify a case of fatal tension pneumocephalus after VS resection in a patient with ventriculo-peritoneal (VP) shunt and to propose possible recommendations to limit the risk of this dramatic complication.

METHODS

A case of fatal tension pneumocephalus after VS resection in presence of hidden CSF fistula is illustrated with pre- and post-operative images.

RESULTS

In the uneventful situation of concomitant post-operative CSF fistula in presence of VP shunt, tension pneumocephalus may occur. The negative pressure created by the shunt system and the presence of osteo-dural defect allow the air to enter and, at the same time, prevent the outflow.

CONCLUSION

After VS resection, tension pneumocephalus can occur as a consequence of CSF fistula from petrosal air cells in the presence of functioning VP shunt. Precautions as pre-operative increase to 'virtual-off' the pressure of the valve, subsequences CT scans after surgery and sealing of the petrous air cells are recommended to avoid such as fatal complication.

Exploring mechanisms of ventricular enlargement in idiopathic normal pressure hydrocephalus: a role of cerebrospinal fluid dynamics and motile cilia

Idiopathic normal pressure hydrocephalus (iNPH) is considered an age-dependent chronic communicating hydrocephalus associated with cerebrospinal fluid (CSF) malabsorption; however, the aetiology of ventricular enlargement in iNPH has not yet been elucidated. There is accumulating evidence that support the hypothesis that various alterations in CSF dynamics contribute to ventricle dilatation in iNPH. This review focuses on CSF dynamics associated with ventriculomegaly and summarises the current literature based on three potential aetiology factors: genetic, environmental and hydrodynamic. The majority of gene mutations that cause communicating hydrocephalus were associated with an abnormal structure or dysfunction of motile cilia on the ventricular ependymal cells. Aging, alcohol consumption, sleep apnoea, diabetes and hypertension are candidates for the risk of developing iNPH, although there is no prospective cohort study to investigate the risk factors for iNPH. Alcohol intake may be associated with the dysfunction of ependymal cilia and sustained high CSF sugar concentration due to uncontrolled diabetes increases the fluid viscosity which in turn increases the shear stress on the ventricular wall surface. Sleep apnoea, diabetes and hypertension are known to be associated with the impairment of CSF and interstitial fluid exchange. Oscillatory shear stress to the ventricle wall surfaces is considerably increased by reciprocating bidirectional CSF movements in iNPH. Increased oscillatory shear stress impedes normal cilia beating, leading to motile cilia shedding from the ependymal cells. At the lack of ciliary protection, the ventricular wall is directly exposed to increased oscillatory shear stress. Additionally, increased oscillatory shear stress may be involved in activating the flow-mediated dilation signalling of the ventricular wall. In conclusion, as the CSF stroke volume at the cerebral aqueduct increases, the oscillatory shear stress increases, promoting motor cilia shedding and loss of ependymal cell coverage. These are considered to be the leading causes of ventricular enlargement in iNPH.

Treatment Outcome of Hydrocephalus Associated with Vestibular Schwannoma

BACKGROUND AND PURPOSE

Managing hydrocephalus in patients with vestibular schwannoma (VS) is controversial. We evaluated the clinical factors associated with hydrocephalus.

METHODS

Between 2000 and 2019, 562 patients with VS were treated at our institute. We applied endoscopic third ventriculostomy (ETV), external ventricular drainage (EVD), and ventriculoperitoneal (VP) shunts to patients with hydrocephalus. The relationships of patient, tumor, and surgical variables with the hydrocephalus outcome were assessed.

RESULTS

Preoperative hydrocephalus (Evans ratio ≥0.3) was present in 128 patients. Six patients who received a preresectional VP shunt were excluded after analyzing the hydrocephalus outcome. Seven of the remaining 122 patients had severe hydrocephalus (Evans ratio ≥0.4). Primary tumor resection, VP shunting, ETV, and EVD were performed in 60, 6, 57, and 5 patients, respectively. The hydrocephalus treatment failure rate was highest in the EVD group. Persistent hydrocephalus was present in five (8%) and seven (12%) patients in the primary resection and ETV groups, respectively. Multivariate analysis revealed that severe hydrocephalus, the cystic tumor, and the extent of resection (subtotal resection or partial resection) were associated with hydrocephalus treatment failure.

CONCLUSIONS

Larger ventricles and a higher cystic portion are predictive of persistent hydrocephalus. We recommend attempting near-total tumor resection in patients with VS.

Refractory communicating hydrocephalus after radiation for small vestibular schwannoma with asymptomatic ventriculomegaly: A case report

Communicating hydrocephalus is a known tumor-related syndrome associated with vestibular schwannoma, which can occur even in small tumor. Radiation has become a popular primary treatment option for small schwannoma; however, little is known about the efficacy and risk accompanying asymptomatic ventriculomegaly on images. We report a case of a 59-year-old woman who suffer from refractory communicating hydrocephalus after radiation for small vestibular schwannoma with asymptomatic ventriculomegaly. After the surgical removal of the tumor, hydrocephalus was gradually improved due to intermittent lumbar puncture and finally resolved without shunt placement. Surgical removal should be considered as the first option for the treatment, even if the patient is asymptomatic and the images revealed a small vestibular schwannoma with only slight ventricular enlargement.

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.

Hydrocephalus after Gamma Knife Radiosurgery for Schwannoma

Objective:

Gamma Knife radiosurgery (GKRS) has been established as an effective and safe treatment for intracranial Schwannoma. However, communicating hydrocephalus can occur after GKRS. The 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 92 patients who underwent GKRS to treat intracranial Schwannoma and developed communicating hydrocephalus. The following parameters were analyzed as potential risk factors for hydrocephalus after GKRS: age, sex, target volume, irradiation dose, prior tumor resection, treatment technique, tumor enhancement pattern, and protein level of cerebrospinal fluid (CSF) after GKRS.

Results:

Of the 92 patients, eight of them developed communicating hydrocephalus. Target volume and tumor enhancement pattern, and protein level of CSF ware associated with the development of hydrocephalus.

Conclusion:

In particular, patients with intracranial Schwannomas with large tumor size, ring enhancement patterns, and high protein level of CSF should be carefully observed.

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.

Subependymal Giant Cell Astrocytoma: Associated Hyperproteinorrhachia Causing Shunt Failures and Nonobstructive Hydrocephalus - Report of Successful Treatment with Long-term Follow-up

Subependymal giant cell astrocytomas (SEGAs) are histologically benign tumors most frequently associated with tuberous sclerosis complex (TSC). Despite their benign histopathological appearance, they may cause unfavorable outcomes due to their intraventricular location. Rarely, SEGA may be associated with hyperproteinorrhachia (high levels of proteins in the cerebrospinal fluid [CSF]), which causes malresorptive, communicating hydrocephalus; certainly, this scenario makes shunt obstruction likely in this patient population. In this report, we illustrate the case of hyperproteinorrhachia in an SEGA patient with known TSC, who presented repeatedly with shunt failure from proteinaceous shunt obstruction. Subsequent surgical resection of the main intraventricular lesion resulted in a dramatic drop in the CSF protein levels and has since prevented further shunt failures. Different treatment concepts and possible pathophysiology are discussed and the pertinent literature is reviewed.

Analysis of risk factors to predict communicating hydrocephalus following gamma knife radiosurgery for intracranial schwannoma

Communicating hydrocephalus (HCP) in vestibular schwannomas (VS) after gamma knife radiosurgery (GKRS) has been reported in the literature. However, little information about its incidence and risk factors after GKRS for intracranial schwannomas is yet available. The objective of this study was to identify the incidence and risk factors for developing communicating HCP after GKRS for intracranial schwannomas. We retrospectively reviewed a total of 702 patients with intracranial schwannomas who were treated with GKRS between January 2002 and December 2015. We investigated patients' age, gender, tumor origin, previous surgery history, tumor volume, marginal radiation dose, and presence of tumor control to identify associations with communicating HCP following GKRS. To make predictive models of communicating HCP, we performed Cox regression analyses and constructed a decision tree for risk factors. In total, 29 of the 702 patients (4.1%) developed communicating HCP following GKRS, which required ventriculo-peritoneal (VP) shunt surgery. Multivariate analyses indicated that age (P = 0.0011), tumor origin (P = 0.0438), and tumor volume (P < 0.0001) were significant predictors of communicating HCP in patients with intracranial schwannoma after GKRS. Using machine-learning methods, we fit an optimal predictive model. We found that developing communicating HCP following GKRS was most likely if the tumor was vestibular origin and had a volume ≥13.65 cm³ . Communicating HCP is not a rare complication of GKRS for intracranial schwannomas. Under specific conditions, communicating HCP following GKRS is warranted for this patient group, and this patient group should be closely followed up.

Relationship Between Muscle Dissection Method and Postoperative Muscle Atrophy in the Lateral Suboccipital Approach to Vestibular Schwannoma Surgery

BACKGROUND

Various techniques are available for occipital skull exposure with muscle dissection, as well as different types of skin incisions in the lateral suboccipital approach to vestibular schwannoma (VS) surgery. The skin incisions are generally classified as S-shaped, J-shaped, or C-shaped. In each method, the technique used for muscle dissection differs in terms of cut, single layer, and multiple layers. This study was performed to identify the relationships among muscle dissection method, skin incision type, and muscle atrophy in the lateral suboccipital approach to surgery for VS.

METHODS

Between 2002 and 2011, we performed surgical resection in 53 patients with VS at Shinshu University Hospital. Of these 53 patients, 35 with radiographic annual follow-up for >3 years after surgery were evaluated retrospectively. These patients included 14 who underwent an S-shaped incision, 6 with a J-shaped incision, and 15 with a C-shaped incision. Bilateral areas of the skin and occipital muscles were measured, and rates of atrophy were calculated and compared among the 3 methods.

RESULTS

Postoperative muscle atrophy was significantly advanced in the second postoperative year, but did not tend to develop further after the third year. The postoperative muscle atrophy ratio was significantly lower in the C-shaped incision group (mean ± SD, 4.0% ± 6.9%) compared with the S-shaped (17.1% ± 9.8%) and J-shaped (17.6% ± 10.0%) incision groups within 2 years after surgery (P < 0.05).

CONCLUSIONS

The C-shaped skin incision with multilayer muscle dissection was associated with significantly reduced postoperative muscle atrophy compared with the other methods.

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.

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.

Technical nuances of resection of giant (> 5 cm) vestibular schwannomas: pearls for success

Removal of vestibular schwannomas (VSs, or acoustic neuromas) remains one of the most challenging operations in neurosurgery. Giant or huge tumors (> 5 cm) heighten these challenges, and technical nuances play a special role in maximizing tumor resection while minimizing complications. In this article, the senior author describes his technical experience with microsurgical excision of giant VSs. The accompanying video further illustrates these details.

The risk factors of symptomatic communicating hydrocephalus after stereotactic radiosurgery for unilateral vestibular schwannoma: the implication of brain atrophy

PURPOSE

To identify the effect of brain atrophy on the development of symptomatic communicating hydrocephalus (SCHCP) after stereotactic radiosurgery (SRS) for sporadic unilateral vestibular schwannomas (VS).

METHODS AND MATERIALS

A total of 444 patients with VS were treated with SRS as a primary treatment. One hundred eighty-one patients (40.8%) were male, and the mean age of the patients was 53±13 years (range, 11-81 years). The mean follow-up duration was 56.8±35.8 months (range, 12-160 months). The mean tumor volume was 2.78±3.33 cm3 (range, 0.03-23.30 cm3). The cross-sectional area of the lateral ventricles (CALV), defined as the combined area of the lateral ventricles at the level of the mammillary body, was measured on coronal T1-weighted magnetic resonance images as an indicator of brain atrophy.

RESULTS

At distant follow-up, a total of 25 (5.6%) patients had SCHCP. The median time to symptom development was 7 months (range, 1-48 months). The mean CALV was 334.0±194.0 mm2 (range, 44.70-1170 mm2). The intraclass correlation coefficient was 0.988 (95% confidence interval [CI], 0.976-0.994; p<0.001). In multivariate analysis, the CALV had a significant relationship with the development of SCHCP (p<0.001; odds ration [OR]=1.005; 95% CI, 1.002-1.007). Tumor volume and female sex also had a significant association (p<0.001; OR=1.246; 95% CI, 1.103-1.409; p<0.009; OR=7.256; 95% CI, 1.656-31.797, respectively). However, age failed to show any relationship with the development of SCHCP (p=0.364).

CONCLUSION

Brain atrophy may be related to de novo SCHCP after SRS, especially in female patients with a large VS. Follow-up surveillance should be individualized, considering the risk factors involved for each patient, for prompt diagnosis of SCHCP.

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.

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.