Fat graft-assisted internal auditory canal closure after retrosigmoid transmeatal resection of acoustic neuroma: Technique for prevention of cerebrospinal fluid leakage

Risk Factors for Central Nervous System Infections After Craniotomy

The central nervous system (CNS) is less prone to infection owing to protection from the brain-blood barrier. However, craniotomy destroys this protection and increases the risk of infection in the brain of patients who have undergone craniotomy. CNS infection after craniotomy significantly increases the patient's mortality rate and disability. Controlling the occurrence of intracranial infection is very important for post-craniotomy patients. CNS infection after craniotomy is caused by several factors such as preoperative, intraoperative, and post-operative factors. Craniotomy may lead to postsurgical intracranial infection, which is mainly associated with surgery duration, infratentorial (posterior fossa) surgery, cerebrospinal fluid leakage, drainage tube placement, unregulated use of antibiotics, glucocorticoid use, age, diabetes, and other systemic infections. Understanding the risk factors of CNS infection after craniotomy can benefit reducing the incidence of intracranial infectious diseases. This will also provide the necessary guidance and evidence in clinical practice for planning to control intracranial infection in patients with craniotomy.

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.

Impact of Reconstruction With Hydroxyapatite Bone Cement on CSF Leak Rate in Retrosigmoid Approach to Vestibular Schwannoma Resection: A Review of 196 Cases

OBJECTIVE

To assess the impact of reconstructive technique on the incidence of cerebrospinal fluid (CSF) leak following retrosigmoid approach to acoustic neuroma resection.

STUDY DESIGN

Retrospective case series.

SETTING

Academic medical center.

PATIENTS

A total of 1,200 patients with acoustic neuromas presented to our institution from 2005 to 2018. Of these, 196 patients underwent surgical resection via a retrosigmoid approach.

INTERVENTION

At our institution, internal auditory canal (IAC) reconstruction following a retrosigmoid approach was performed with bone wax and muscle plug or Norian hydroxyapatite bone cement from 2005 to 2013. Starting in 2014, a newer model of bone cement, Cranios hydroxyapatite, was used exclusively for reconstruction.

MAIN OUTCOME MEASURES

Rates of CSF leak were evaluated across different methods of IAC reconstruction and types of bone cement. Patients whose leaks were attributable to the craniectomy site were excluded from analysis.

RESULTS

The postoperative CSF leak rate among patients who did not receive bone cement for IAC reconstruction was 15.6% (n.5). The leak rate amongst patients who received Norian bone cement was 6.3% (n.4). After introduction of Cranios bone cement, the total leak rate decreased to 1% (n.1). Compared with all other types of closure, Cranios had a significantly reduced rate of postoperative CSF leak (p < 0.005). The leak rate following Cranios versus Norian was also significantly reduced (p < 0.05). Leak rate was not affected by tumor size (p.0.30) or age (p.0.43).

CONCLUSION

CSF leak rate following acoustic neuroma resection was significantly reduced by introduction of Cranios hydroxyapatite bone cement.

The Role of Fast Imaging Employing Steady-State Acquisition (FIESTA) Magnetic Resonance Imaging for Assessment of Delayed Enhancement of Fat Graft Packing on Postoperative Imaging After Vestibular Schwannoma Surgery

OBJECTIVE

To investigate the role and efficacy of fast imaging employing steady-state acquisition (FIESTA) imaging in distinguishing fat graft enhancement from residual or recurrent tumor after vestibular schwannoma (VS) surgery.

METHODS

A retrospective study of 33 patients who underwent VS resection via the retrosigmoid or translabyrinthine approach with fat graft reconstruction was performed. Magnetic resonance imaging (MRI) was collected at different time points: preoperative, immediate postoperative (24-48 hours), delayed postoperative (3-6 months after surgery), and yearly postoperative. The image sets contained T1, T2, fat-suppressed T1-weighted with gadolinium, and FIESTA. The radiographs were analyzed for tumor recurrence by the primary neurosurgeon and an independent blinded neuroradiologist. If fat-suppressed T1-weighted images demonstrated postoperative enhancement in the resection bed, a comparison was made with FIESTA imaging.

RESULTS

At 3-6 months postoperatively and at 1 year and beyond, 28 (84.8%) and 33 (100%) of patients, respectively, displayed delayed enhancement of the fat graft on postgadolinium fat-suppressed T1-weighted MRI. The enhancement seen on postgadolinium, fat-suppressed, T1-weighted MRI consistently correlated with the characteristic fat graft signal on FIESTA imaging and not tumor recurrence. FIESTA imaging was able to distinguish residual tumor from enhancing fat graft compared with postgadolinium, fat-suppressed, T1-weighted MRI (P < 0.0001) due to distinctive signaling patterns.

CONCLUSIONS

FIESTA is an effective tool in discerning fat graft enhancement from residual or recurrent tumor on delayed postoperative imaging after VS resection. Fat graft used in reconstruction consistently enhances on delayed postoperative postgadolinium, fat-suppressed, T1-weighted imaging, which correlates with the fat graft signal seen on FIESTA images.

Cerebrospinal Fluid Leakage During Temporal Bone Surgery: Selecting Intra-operative Dural Closure with a Dumbbell-Shaped Muscle Graft as a Surgical Approach

Cerebrospinal fluid (CSF) leakages of the temporal bone may arise during mastoid surgery. The leakages can have multiple potential etiologies, for instance, using a cutting burr near the bony tegmen or monopolar electrocautery on the surface of the dura mater. In this paper, we introduced an effective and simple technique for the management of CSF leakages of the temporal bone. In a prospective case series, 36 patients (16 males and 20 females) who have had an experience of incidental or inevitable CSF otorrhea or otorhinorrhea during temporal bone surgery were selected. All patients were treated using a muscle graft in a dumbbell-shaped design through the dura defect at the Amir-Alam University Hospital between April 2005 and November 2008. The mean size of the defects was 5 mm (a range of 2-10 mm). A dumbbell-shaped autologous muscle graft was immediately successful in sealing the leakage in all patients. Only five patients (13.8%) had some evidence of leakage remaining on the day after the operation, which was subsequently resolved by conservative management in four of them (11.1%). Only one patient (2.7%) was subjected to a second operation for a new defect. Recurrence of CSF leakage or other related complications were not observed during about 7 years of follow up. A free autologous muscle graft, using the dumbbell technique through a small to moderate dura defect is an effective, easily performed, and safe method to seal iatrogenic leakages of the temporal bone.