Factors affecting postoperative cerebrospinal fluid leaks after retrosigmoidal craniotomy for vestibular schwannomas

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.

Clinical practice guideline on the management of vestibular schwannoma

INTRODUCTION

Vestibular schwannoma (VS) is the most common tumour of the cerebellopontine angle. The greater accessibility to radiological tests has increased its diagnosis. Taking into account the characteristics of the tumour, the symptoms and the age of the patient, three therapeutic strategies have been proposed: observation, surgery or radiotherapy. Choosing the most appropriate for each patient is a frequent source of controversy.

MATERIAL AND METHODS

This paper includes an exhaustive literature review of issues related to VS that can serve as a clinical guide in the management of patients with these lesions. The presentation has been oriented in the form of questions that the clinician usually asks himself and the answers have been written and/or reviewed by a panel of national and international experts consulted by the Otology Commission of the SEORL-CCC.

RESULTS

A list has been compiled containing the 13 most controversial thematic blocks on the management of VS in the form of 50 questions, and answers to all of them have been sought through a systematic literature review (articles published on PubMed and Cochrane Library between 1992 and 2023 related to each thematic area). Thirty-three experts, led by the Otology Committee of SEORL-CCC, have analyzed and discussed all the answers. In Annex 1, 14 additional questions divided into 4 thematic areas can be found.

CONCLUSIONS

This clinical practice guideline on the management of VS offers agreed answers to the most common questions that are asked about this tumour. The absence of sufficient prospective studies means that the levels of evidence on the subject are generally medium or low. This fact increases the interest of this type of clinical practice guidelines prepared by experts.

Differences in mastoid pneumatization between Asians and Caucasians

BACKGROUND

Anatomical differences of the mastoid pneumatization in Asian and Caucasian patients must be considered when performing the retrosigmoid craniotomy since it may have implications to avoid specific complications such as cerebrospinal fluid infections or fistula.

METHODS

We selected cranial CT scans of 120 Asian and 120 Caucasian patients, who were treated at the Mitsui Memorial Hospital (Japan) and at the Heidelberg University Hospital (Germany). Mastoid pneumatization was classified according to the relationship of the mastoid air cells (MAC) to the sigmoid sinus (Type I - III). The risk of mastoid air cell opening through craniotomy increases from Type I to III. Comparative analyses between gender and ethnicities were performed using the Chi² Test and the independent T-Test and considered significant if p < 0.05.

RESULT

In Caucasians, Type III pneumatization was significantly overrepresented compared to Type II or I, compared to the Asian cohort (Type III:II:I in Caucasians = 60 %:26 %:14 %; in Asians = 28 %:43 %:29 %). Importantly, we found significant differences in pneumatization types between Caucasians and Asians in both gender subgroups (m: Type III 60 % vs 35 %; Type II 30 % vs 36.7 %; Type I 10 % vs 28.3 %, p = 0.008; f: Type III 60 % vs 23.3 %, Type II 21.7 % vs 48.3 %, Type III 18.3 % vs 28.3 %, p < 0.001; Chi² Test).

CONCLUSION

Caucasian patients are more prone to the opening of the mastoid air cells than Asian patients when performing a retrosigmoid craniotomy due to differences in the degree of mastoid pneumatization. This may help to avoid complications such as postoperative infections or cerebrospinal-fluid fistula.

Association of Postoperative Sigmoid Sinus Occlusion and Cerebrospinal Fluid Leak in Translabyrinthine Surgery

OBJECTIVE

To characterize the incidence of sigmoid sinus occlusion (SSO) following translabyrinthine (TL) surgery for posterior fossa tumor resection and determine the association with cerebrospinal fluid (CSF) leak.

STUDY DESIGN

Retrospective case series.

SETTING

Tertiary referral center.

METHODS

Patients undergoing TL surgery for vestibular schwannoma from 2012 to 2020 were included. Demographic data, medical history, preoperative tumor length and volume, and postoperative complications including CSF leak were recorded. Neuroradiology review of postoperative magnetic resonance imaging was used to determine the presence or absence of flow through the sigmoid sinus.

RESULTS

Of 205 patients undergoing TL, 21 (10.2%) experienced CSF leak postoperatively. Overall 56 (27%) demonstrated SSO on immediate postoperative magnetic resonance imaging. CSF leaks were more likely in those with SSO (19.6%) than those without SSO (6.7%; odds ratio, 3.54 [95% CI, 1.25-10.17]). Tumor volume and body mass index were not significantly associated with CSF leak. In total, 105 (51%) patients had some degree of sigmoid sinus thrombosis, but nonocclusive thrombosis was not associated with CSF leak.

CONCLUSION

SSO after TL approaches is common and appears to be significantly associated with postoperative CSF leak development. Minimizing manipulation of the sigmoid sinus during TL surgery and compression after surgery may have a role in preventing CSF leak.

The incidence of postoperative cerebrospinal fluid leakage after elective cranial surgery: a systematic review

Cerebrospinal fluid (CSF) leakage is a major complication after elective neurosurgical procedures. The aim of this systematic literature review is to summarize the incidence rates of postoperative cerebrospinal fluid leakage for neurosurgical procedures, classified by surgical approach. The Pubmed, Cochrane, Embase, and Web of Science databases were searched for studies reporting the outcome of patients undergoing elective neurosurgical procedures. The number of patients, surgical approach, and indication for surgery were recorded for each study. Outcomes related to CSF leakage such as clinical manifestation and treatment were reported as well. One hundred and thirteen studies were included, reporting 94,695 cases. Overall, CSF leaks were present in 3.8% of cases. Skull base surgery had the highest rate of CSF leakage with 6.2%. CSF leakage occurred in 5.9% of anterior skull base procedures, 6.4% of middle fossa, and 5.2% of transpetrosal surgeries. 5.8% of reported infratentorial procedures were complicated by CSF leakage versus 2.9% of supratentorial surgeries. CSF leakage remains a common serious adverse event after cranial surgery. There exists a need for standardized procedures to reduce the incidence of postoperative CSF leakage, as this serious adverse event may lead to increased health care costs.

Bone Cement Internal Auditory Canal Reconstruction to Reduce CSF Leak After Vestibular Schwannoma Retrosigmoid Approach

OBJECTIVE

To describe rates of cerebrospinal fluid (CSF) rhinorrhea after reconstruction of the IAC with calcium phosphate bone cement during retrosigmoid resections of vestibular schwannomas.

METHODS

A retrospective chart review of 177 patients who underwent retrosigmoid craniotomy and opening of the internal auditory canal for resection of a vestibular schwannoma between January 2016 and September 2019 at a tertiary referral center. Patients with other cerebellopontine angle tumor histology, neurofibromatosis type II, or those undergoing revision surgeries were excluded.

RESULTS

Out of 177 patients, six patients (3.4%) developed postoperative rhinorrhea. Four patients (2.3%) were taken back to the OR for mastoidectomy and repair of CSF leak. Three of these patients were noted to have a CSF leak from the peri-labyrinthine air cells, and one was found to have a leak from the craniotomy site communicating with the mastoid air cells. Two patients were conservatively managed with diuretics and had resolution of their CSF leak. Six patients (3.4%) were readmitted for postoperative infection. Two patients were diagnosed with meningitis (1.1%), one aseptic and one H. Influenza, and three patients developed surgical site infections (1.6%). One patient was empirically treated with antibiotics and ultimately had a negative CSF culture.

CONCLUSIONS

Our results demonstrate that the use of calcium phosphate bone cement for IAC closure in retrosigmoid resection of vestibular schwannomas is a safe and effective technique with low rates of postoperative CSF rhinorrhea.

Factors associated with cerebrospinal fluid leak after a retrosigmoid approach for cerebellopontine angle surgery

Background

The retrosigmoid approach represents a crucial surgical route to address different lesions in the cerebellopontine angle but cerebrospinal fluid (CSF) leak still remains the most frequent complication after this approach. Here, we analyzed the impact of different factors in CSF leak development after a retrosigmoid approach. Identifying risk factors related to a specific approach may help the surgeon to tailor the perioperative management and to appropriately counsel patients regarding their risk profile.

Methods

We retrospectively reviewed the clinical, surgical, and outcome data of 103 consecutive patients (M/F, 47/56; mean follow-up 35.6 ± 23.9 months) who underwent a retrosigmoid approach for different cerebellopontine angle pathologies and studied the impact of different factors on the occurrence of a CSF leak to univariate and multivariate analysis.

Results

Seventy-nine patients (76.7%) were operated for tumors growing in the cerebellopontine angle. Twenty-four patients (23.2%) underwent microvascular decompression to treat a drug-resistant trigeminal neuralgia. Sixteen patients (15.5%) developed CSF leak in the postoperative course of which six underwent surgical revision. Performing a craniectomy as surgical procedure (P = 0.0450) and performing a reopening procedure (second surgery; P = 0.0079) were significantly associated to a higher risk of developing CSF leak. Moreover, performing a reopening procedure emerged as an independent factor for CSF developing on multivariate analysis (P = 0.0156).

Conclusion

Patients submitted to craniectomy and patients who underwent a second surgery showed an higher CSF leak rate. Ongoing improvement of biomaterial technology may help neurosurgeons to prevent this potentially life-threatening complication.

Prevention of cerebrospinal fluid leak after vestibular schwannoma surgery: a case-series focus on mastoid air cells' partition

BACKGROUND

Petrous bone pneumatization may be related to cerebrospinal fluid (CSF) leak secondary to vestibular schwannoma surgery.

OBJECTIVE

To assess the association between petrous bone pneumatization and CSF leak in vestibular schwannoma surgery.

METHODS

A retrospective study included 222 consecutive vestibular schwannoma patients treated via a retrosigmoid or translabyrinthine approach in a 17-year period in one University Hospital. Association of CSF leak and petrous bone pneumatization, as seen on CT scans, was assessed on ANOVA and Student's t or Chi-squared test in case of non-parametric distribution.

RESULTS

One hundred and 75 resections were performed on a retrosigmoid approach and 47 on a translabyrinthine approach. Mean age was 53.6 ± 12.9 years. Mean follow-up was 5 years 6 months. Twenty-six patients (11.7%) showed CSF leak and 8 (3.6%) meningitis. Approach (p = 0.800), gender (p = 0.904), age (p = 0.234), body-mass index (p = 0.462), tumor stage (p = 0.681) and history of schwannoma surgery (p = 0.192) did not increase the risk of CSF leak. This risk was unrelated to mastoid pneumatization (p = 0.266). There was a highly significant correlation between internal acousticus meatus (IAM) posterior wall pneumatization and CSF leak after retrosigmoid surgery (p = 0.008). Eustachian tube packing in the translabyrinthine approach did not decrease risk of CSF leak (p = 0.571).

CONCLUSION

Degree of petrous bone pneumatization was not significantly related to risk of CSF leak, but pneumatization of the posterior IAM wall increased this risk in retrosigmoid surgery. Eustachian tube packing in the translabyrinthine approach is not sufficient to prevent postoperative CSF leak. Both approaches had similar rates of CSF leaks, around 12%.

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.

Postoperative Hearing Preservation in Patients Undergoing Retrosigmoid Craniotomy for Resection of Vestibular Schwannomas: A Systematic Review of 2034 Patients

BACKGROUND

Vestibular schwannomas (VS) are benign tumors derived from Schwann cells ensheathing the vestibulocochlear nerve. The retrosigmoid (RS) surgical approach is useful to resect tumors of multiple sizes while affording the possibility of preserving postoperative hearing.

OBJECTIVE

To conduct a systematic review of published literature investigating hearing preservation rates in patients who underwent the RS approach for VS treatment.

METHODS

The PubMed, Scopus, and Embase databases were surveyed for studies that reported preoperative and postoperative hearing grades on VS patients who underwent RS treatment. Hearing preservation rates were calculated, and additional patient demographic data were extracted. Tumor size data were stratified to compare hearing preservation rates after surgery for intracanalicular, small (0-20 mm), and large (>20 mm) tumors.

RESULTS

Of 383 deduplicated articles, 26 studies (6.8%) met eligibility criteria for a total of 2034 patients with serviceable preoperative hearing, for whom postoperative hearing status was evaluated. Aggregate hearing preservation was 31% and 35% under a fixed and random effects model, respectively. A mixed effects model was used to determine hearing preservation rates depending on tumor size, which were determined to be 57%, 37%, and 12% for intracanalicular, small, and large tumors, respectively. Significant cross-study heterogeneity was found (I2 = 93%, τ2 = .964, P < .01; Q = 287.80, P = < .001), with rates of hearing preservation ranging from 0% to 100%.

CONCLUSION

Tumor size may have an effect on hearing preservation rates, but multiple factors should be considered. Discussion of a patient's expectations for hearing preservation is critical when deciding on VS treatment plans.

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.

Bone Sandwich Closure Technique for Posterior Fossa Craniectomy

Background  Surgery of posterior fossa including cerebellopontine (CP) angle involves either craniectomy or craniotomy. While there has been precedence of craniotomy in recent practice, the preferred access in resource-strapped centers still remains been craniectomy. Although the latter offers an excellent exposure, it is believed to carry increased risk of postoperative pseudomeningocoele and cerebrospinal fluid (CSF) leak compared with craniotomy. Methods  We have suggested a technique by which after standard craniectomy for the posterior fossa surgeries the bony defect is covered by Gelfoam bone sandwich (GBS) technique. We studied this technique over a period of 25.6 years in 1,028 patients. Results and Conclusion  We analyze the risk of pseudomeningocoele and CSF leak in our patients using GBS technique and reviewed literature to compare our outcomes with standard craniotomy and craniectomy procedures.

Surgical treatment of sporadic vestibular schwannoma in a series of 1006 patients

The management of sporadic vestibular schwannoma (VS) has evolved in the last decades. The aim of this study was to analyse the evolution in surgical outcomes of VSs operated by a neurotological team between 1990 and 2006 by different approaches. A monocentric retrospective review of medical charts of 1006 patients was performed. In order to assess eventual changes and progress, the 17-years period was divided in three periods, each one comprehending 268 VS (1990-1996), 299 VS (1997-2001), and 439 VS (2002-2006). Mean follow-up was 5.9 ± 2.4 years. Overall, complete VS removal was achieved in 99.4% of cases. Mortality rate was 0.3%, meningitis and CSF leaks were observed in 1.2 % and 9 % of the cases, respectively. CSF leakage decreased from 11.6% to 7.1% between the first and last period (p < 0.01) as well as revision surgery from 3.4 % to 0.9 % (p < 0.05). Facial nerve was anatomically preserved in 97.7% of cases. At one year, a good facial nerve function was observed in 85.1% of patients (grade I and II of House-Brackmann grading scale), which ranged between the first and last period from 78.4% to 87.6% (p <0.05). At one year, hearing preservation was obtained in 61.6% of patients, which increased from the first period to the last one from 50.9% to 69.0% (p < 0.05) (class A+B+C from the AAO-HNS classification). Useful hearing (class A+B) was observed in 33.5% of cases overall, with 21.8% and 42% in the first and last period, respectively (p < 0.01). Surgical outcomes of sporadic vestibular schwannoma have improved concerning facial nerve function outcomes, hearing preservation and cerebrospinal fluid (CSF) leaks, mainly due to the neuro-otological team's experience. Functional results after complete microsurgical removal of large VS depend on experience gained on small VS removal.

Massive Cerebrospinal Fluid Leak of the Temporal Bone

Cerebrospinal fluid (CSF) leakage of the temporal bone region is defined as abnormal communications between the subarachnoidal space and the air-containing spaces of the temporal bone. CSF leak remains one of the most frequent complications after VS surgery. Radiotherapy is considered a predisposing factor for development of temporal bone CSF leak because it may impair dural repair mechanisms, thus causing inadequate dural sealing. The authors describe the case of a 47-year-old man with a massive effusion of CSF which extended from the posterior and lateral skull base to the first cervical vertebrae; this complication appeared after a partial enucleation of a vestibular schwannoma (VS) with subsequent radiation treatment and second operation with total VS resection.

Evaluation of Non-Watertight Dural Reconstruction with Collagen Matrix Onlay Graft in Posterior Fossa Surgery

OBJECTIVE

Many surgeons advocate for watertight dural reconstruction after posterior fossa surgery given the significant risk of cerebrospinal fluid (CSF) leak. Little evidence exists for posterior fossa dural reconstruction utilizing monolayer collagen matrix onlay graft in a non-watertight fashion. Our objective was to report the results of using collagen matrix in a non-watertight fashion for posterior fossa dural reconstruction.

METHODS

We conducted a retrospective review of operations performed by the senior author from 2004-2011 identified collagen matrix (DuraGen) use in 84 posterior fossa operations. Wound complications such as CSF leak, infection, pseudomeningocele, and aseptic meningitis were noted. Fisher's exact test was performed to assess risk factor association with specific complications.

RESULTS

Incisional CSF leak rate was 8.3% and non-incisional CSF leak rate was 3.6%. Incidence of aseptic meningitis was 7.1% and all cases resolved with steroids alone. Incidence of palpable and symptomatic pseudomeningocele in follow-up was 10.7% and 3.6% respectively. Postoperative infection rate was 4.8%. Previous surgery was associated with pseudomeningocele development (p<0.05).

CONCLUSION

When primary dural closure after posterior fossa surgery is undesirable or not feasible, non-watertight dural reconstruction with collagen matrix resulted in incisional CSF leak in 8.3%. Incidence of pseudomeningocele, aseptic meningitis, and wound infection were within acceptable range. Data from this study may be used to compare alternative methods of dural reconstruction in posterior fossa surgery.

Are there modifiable risk factors to prevent a cerebrospinal fluid leak following vestibular schwannoma surgery?

OBJECT

The following study was conducted to identify risk factors for a postoperative CSF leak after vestibular schwannoma (VS) surgery.

METHODS

The authors reviewed a prospectively maintained database of all patients who had undergone resection of a VS at the Mayo Clinic between September 1999 and May 2013. Patients who developed a postoperative CSF leak within 30 days of surgery were compared with those who did not. Data collected included patient age, sex, body mass index (BMI), tumor size, tumor side, history of prior tumor treatment, operative time, surgical approach, and extent of resection. Both univariate and multivariate regression analyses were performed to evaluate all variables as risk factors of a postoperative CSF leak.

RESULTS

A total of 457 patients were included in the study, with 45 patients (9.8%) developing a postoperative CSF leak. A significant association existed between increasing BMI and a CSF leak, with those classified as overweight (BMI 25-29.9), obese (BMI 30-39.9), or morbidly obese (BMI≥40) having a 2.5-, 3-, and 6-fold increased risk, respectively. Patients undergoing a translabyrinthine (TL) approach experienced a higher rate of CSF leaks (OR 2.5, 95% CI 1.3-4.6; p=0.005), as did those who had longer operative times (OR 1.04, 95% CI 1.02-1.07; p=0.0006). The BMI, a TL approach, and operative time remained independent risk factors on multivariate modeling.

CONCLUSIONS

Elevated BMI is a risk factor for the development of a postoperative CSF leak following VS surgery. Recognizing this preoperatively can allow surgeons to better counsel patients regarding the risks of surgery as well as perhaps to alter perioperative management in an attempt to decrease the likelihood of a leak. Patients undergoing a TL approach or having longer operative times are also at increased risk of developing a postoperative CSF leak.

Galeal tack-up sutures to prevent subgaleal cerebrospinal fluid collection

Objective

Postoperative subgaleal cerebrospinal fluid (CSF) collection is considered as one of the common minor surgical complication which can lead to prolonged hospitalization. We introduce "galeal tack-up suture" to prevent postoperative subgaleal CSF collection.

Methods

Galeal tack-up suture consists of various surgical techniques which aim to fix galea to cranium in order to prevent CSF pooling in subgaleal space. A total of 87 patients who underwent craniotomy were divided into two groups while closing the wound : group A with galeal tack-up suture and group B with routine wound closure without galeal tack-up suture. The patients were observed for postoperative subgaleal CSF collection.

Results

Among 87 cranitomy cases, galeal tack-up suture was performed in 32 cases and routine wound closure was done in 55 cases. Postoperative subgaleal CSF collection occurred in 13 cases (15%) in which 12 cases occurred in group B patients and 1 case occurred in group A patients (p=0.026).

Conclusion

Galeal tack-up suture is an easy and effective technique in wound closure to prevent postoperative CSF collection.

Petrous bone pneumatization is a risk factor for cerebrospinal fluid fistula following vestibular schwannoma surgery

BACKGROUND

For the prevention of postoperative CSF fistula a better understanding of origins and risk factors is necessary.

OBJECTIVE

To identify the petrous bone air cell volume as a risk factor for developing CSF fistula, we performed a retrospective analysis.

METHODS

From 2000 to 2007 519 patients had a retrosigmoidal surgical removal of a vestibular schwannoma. The 22 who had a postoperative CSF fistula were chosen for evaluation in addition to 78 patients who were randomly selected in 4 equally sized cohorts: male/female with small/large tumors. Preoperative CT scans were analyzed regarding petrous bone air cell volume, area of visible pneumatization at the level of the internal auditory canal (IAC), tumor grade, and sex.

RESULTS

: Women developed nearly half as many CSF fistulas (2.7%) as men (5.2%). The mean volume of the petrous bone air cells was 10.97 mL (SD, 4.9; range, 1.38-27.25). It was significantly lower for women (mean, 9.23 mL; SD, 3.8) than for men (mean, 12.5 mL; SD, 5.28; P = .0008). The mean air cell volume of CSF-fistula patients was 13.72 mL (SD, 5.22). The difference concerning the air cell volume between patients who developed CSF fistulas and patients from the control group was significant (P = .0042). There was a significant positive correlation between the air cell volume and the area of pneumatization in one CT slide at the level of the IAC.

CONCLUSION

The higher incidence of CSF fistulas in men compared with women can be explained by means of differently pneumatized petrous bones. A high amount of petrous bone pneumatization has to be considered as a risk factor for the development of postoperative CSF fistula after vestibular schwannoma surgery.

How obliteration of petrosal air cells by vestibular schwannoma influences the risk of postoperative CSF fistula

INTRODUCTION

For postoperative CSF-fistula prevention a better understanding of its origins and risk factors is necessary. To identify the role of the tumor growth for the risk to develop CSF-fistula we performed a retrospective analysis.

METHODS

519 patients between the years 2000 and 2007 had a retrosigmoidal surgical removal of vestibular schwannoma in a standardized procedure. 22 CSF-fistula-patients were chosen for evaluation. 78 patients were randomly selected as control group in four equally sized cohorts: male/female with small/large tumors. Preoperative CT-scans were analyzed regarding IAC-length, diameter of the IAC porus (IAP), tumor size and pneumatization of the posterior wall (PW) of the IAC.

RESULTS

The mean length of the IAC was 1.2 cm, SD 0.17. There was a significant difference between the diameter of the IAP in cases of small tumors and those of large tumors. Patients with small tumors also showed a larger fraction with visible pneumatization of the PW (34.88%) in the CT-scan than patients with large tumors (24.07%). There is a positive correlation between tumor grade and diameter of the IAP. At the same time there is an inverse correlation between tumor grade and pneumatization of the PW.

CONCLUSIONS

Widening of the IAC by tumor growth may leads to obliteration of air cells in the PW and therefore can be protective concerning CSF-fistula. At the same time patients with small tumors and a visible pneumatization in the PW must be expected to have a higher risk of CSF-fistula.

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.