Cerebrospinal fluid leak after vestibular schwannoma surgery

Through mastoid air cells, petrous ridge or internal auditory canal.

Since the mid 20th century, postoperative cerebrospinal fluid leaks have been a well-established complication of vestibular schwannoma surgery. Dandy first described CSF leaks as a complication after suboccipital craniotomy for the removal of a vestibular schwannoma ¹⁾.

Because CSF leak rates were common and complications of leaks were significant, multiple attempts have been made to decrease leak rates. In the 1960s, introduction of the abdominal fat graft significantly reduced the postoperative CSF leak rates in the translabyrinthine approach ²⁾.

In addition, muscle and bone wax were later introduced for closure in the retrosigmoid approach. Because CSF leaks have continued, surgeons have modified closure techniques and have included a host of different materials to reduce the CSF leak rate even further ³⁾.

Postoperative cerebrospinal fluid leak is reported in 2% to 30% of cases following vestibular schwannoma surgery ^{4) 5) 6)}. ⁷⁾ , but the average leak rate appears to be approximately 10% ⁸⁾.

Patients who had undergone surgical resection of a vestibular schwannoma from 1995 to 2010 were identified in the California Office of Statewide Health Planning and Development database. The most common admission diagnoses were identified by International Classification of Disease, ninth Revision, diagnosis codes, and predictors of readmission with CSF leak were determined using logistic regression.

A total of 6820 patients were identified. CSF leak, though a relatively uncommon cause of admission after discharge (3.52% of all patients), was implicated in nearly half of 490 readmissions (48.98%). Significant independent predictors of readmission with CSF leak were male sex (odds ratio [OR] 1.72, 95% confidence interval [CI] 1.32-2.25), first admission at a teaching hospital (OR 3.32, 95% CI 1.06-10.39), CSF leak during first admission (OR 1.84, 95% CI 1.33-2.55), obesity during first admission (OR 2.10, 95% CI 1.20-3.66), and case volume of first admission hospital (OR of log case volume 0.82, 95% CI 0.70-0.95). Median time to readmission was 6 d from hospital discharge.

This study has quantified CSF leak as an important contributor to nearly half of all readmissions following vestibular schwannoma surgery. We propose that surgeons should focus on technical factors that may reduce CSF leakage and take advantage of potential screening strategies for the detection of CSF leakage prior to first admission discharge ⁹⁾.

Review of 1,922 subjects who underwent resection of vestibular schwannomas from 1970 to 2010.

INTERVENTION: Surgical resection of vestibular schwannoma.

MAIN OUTCOME MEASURES: Patient demographics, surgical approach used, CSF leak incidence, meningitis, treatment, and success in the management of CSF leaks.

RESULTS: Postoperative CSF leaks were observed in 12.9% of our patients. There was no significant difference between the type of approach and the presence of CSF leak with translabyrinthine, suboccipital and middle fossa CSF leak rates of 12%, 12%, and 13%, respectively (p = 0.07). Patients presented with a wound leak or rhinorrhea almost equally. Ultimately, 92% of patients with rhinorrhea underwent surgical intervention. The probability of a patient with rhinorrhea requiring a second intervention was higher when the initial intervention was conservative rather than surgical. However, the probability of a patient with a wound leak requiring a second intervention was essentially the same when initially treated conservatively or surgically.

CONCLUSION: Our data suggests that there is no difference in CSF leak rates between the different surgical approaches. The appropriate treatment strategy is dependent on the presentation of the CSF. Although conservative treatment is effective for managing wound leaks, it is less effective in managing patients with rhinorrhea. Therefore, surgical treatments should play an early role in the treatment algorithm of patients with CSF rhinorrhea ¹⁰⁾.

Cerebrospinal fluid rhinorrhea remains a significant cause of morbidity after resection of vestibular schwannomas (VSs), with rates of rhinorrhea after this procedure reported to range between 0 and 27%. Baird et al. investigated whether reconstruction of the drilled posterior wall of the porus acusticus with hydroxyapatite cement (HAC) would decrease the incidence of postoperative CSF rhinorrhea.

A prospective observational study of 130 consecutive patients who underwent surgery for reconstruction of the posterior wall of the drilled porus acusticus with HAC was conducted between October 2002 and September 2005. All patients underwent a retrosigmoid transmeatal approach for VS resection and were followed up to document cases of CSF rhinorrhea, incisional CSF leak, meningitis, or rhinorrhea-associated meningitis. A cohort of 150 patients with VSs who were treated with the same surgical approach but without HAC reconstruction served as a control group.

The authors found that HAC reconstruction of the porus acusticus wall significantly reduced the rate of postoperative CSF rhinorrhea in their patients. In the patients treated with HAC, rhinorrhea developed in only three patients (2.3%) compared with 18 patients (12%) in the control group. This was a statistically significant finding (p = 0.002, odds ratio = 5.8).

The use of HAC in the reconstruction of the drilled posterior wall of the porus acusticus, occluding exposed air cells, greatly reduces the risk of CSF rhinorrhea ¹¹⁾.

Data from 215 patients who had surgery from 1995 to 2000 manifested a 6.6% CSF leak rate for primary surgeries. This compared favorably with the authors' 17% overall CSF leak rate in 555 total primary surgeries performed between 1979 and 1995. Translabyrinthine closure was performed with dural sutures used as a sling across the posterior fossa dura and abdominal fat placed as a series of corks through the sutures. Abdominal fat was used to obliterate the mastoid cavity in conjunction with aditus and mastoid obliteration. Attention must be paid to soft tissue obliteration of potentially open air cell tracts. Retrosigmoid transmeatal closure was performed with a soft tissue graft in the internal auditory canal drill-out held in position by a “saloon-door” dural flap. Bone wax was used to block perimeatal cells in all cases. Watertight dural closure was achieved with a sutured temporalis fascia graft. Abdominal fat obliteration of the mastoidectomy cavity was performed with an additional firm pressure from the “Palva” periosteal flap. Middle cranial fossa closure was performed with attention to potential air cell tracts of the internal auditory canal drill-out, as well as abdominal fat graft, tissue glue, and bone wax. Fibrin glue was used in all approaches to temporarily secure fat in situ. Management of CSF leaks starts with nonoperative measures including bed rest, oversewing of incisional wounds, and placement of a lumbar subarachnoid spinal fluid diversion drain. If these conservative measures fail, repeat exploration is necessary and is directed at identifying and corking the cell or cells (usually perimeatal or perilabyrinthine) opening directly into the posterior fossa.

Evolution in surgical techniques, with particular attention to exposed air cell tracts, abdominal fat graft, and Palva periosteal flap for closure, has had a significant effect in decreasing the author's CSF leak rate after vestibular schwannoma surgery. Conservative management was successful in approximately 50% of cases. Repeat exploration, when needed, was directed at blocking the air cell tract (usually perimeatal or perilabyrinthine) responsible for the CSF leak ¹²⁾.

In 624 cases of acoustic neuroma the authors observed an overall incidence of 10.7% for CSF leak. The rate of leakage was significantly lower in the last 9 years compared with the first 15, most likely because of the abandonment of the combined translabyrinthine (TL)-middle fossa exposure. There was no difference in the leakage rate between TL and retrosigmoid (RS) approaches, although there were differences in the site of the leak (wound leaks occurred more frequently after a TL and otorrhea after an RS approach, respectively). Tumor size (maximum extracanalicular diameter) had a significant effect on the leakage rate overall and for RS but not for TL procedures. The majority of leaks ceased with nonsurgical treatments (18% with expectant management and 49% with lumbar CSF drainage). However, TL leaks (especially rhinorrhea) required surgical repair significantly more often than RS leaks. This has not been reported previously.

CONCLUSIONS: The rate of CSF leakage after TL and RS procedures has remained stable. Factors influencing its occurrence include tumor size but not surgical approach. The TL-related leaks had a significantly higher surgical repair rate than RS-related leaks, an additional factor to consider when choosing an approach. The problem of CSF leakage becomes increasingly important as nonsurgical treatments for acoustic neuroma are developed ¹³⁾.