Treatment of Lateral Skull Base and Posterior Cranial Fossa Lesions Utilizing the Extended Middle Cranial Fossa Approach

Posterior cranial fossa meningiomas: Comparison of results between patients older and younger than 70 years

Introduction

Surgical strategy for meningioma resection in the elderly is controversial: diverse studies in the literature have pointed at the age as a negative prognostic factor in terms of postoperative results.

Research question

The aim of this study is to compare surgical outcomes after resection of posterior fossa meningiomas in <70 and ≥ 70 years-old age groups.

Material and methods

We reviewed 72 patients affected by posterior fossa meningiomas who underwent surgical treatment at San Filippo Neri Hospital, Rome, Italy between September 2010 and December 2022. We analyzed data regarding tumor size, clinical presentation, extent of resection and complication/mortality.

Results

The groups consisted of 52 (72,2%) young and 20 (27,8%) elderly patients. Gross total resection rate was significantly higher among youngsters (p = 0,013), mainly for planned subtotal removal in older patients. At 3-month follow-up, clinical improvement was seen in 19 (36,5%) young and 7 (35,0%) elderly patients, which raised at last follow-up, being 84,6% (44) and 80,0% (16), respectively (p = 0,406). Two cases of progression/recurrence among the elderly and 1 among youngsters were observed; one case of mortality among the elderly was reported.

Discussion and conclusions

Safety data regarding postoperative complications and mortality in our series seem to confirm that there is no significant difference between older and younger patients, as long as older patients are carefully selected. Therefore, if surgery is proposed, it should be radical if gross total resection could be safely attempted.

Middle Cranial Fossa Approach for Sporadic Vestibular Schwannoma

The middle fossa approach is an excellent technique for removing appropriate vestibular schwannomas in patients with serviceable hearing. Knowledge of the intricate middle fossa anatomy is essential for optimal outcomes. Gross total removal can be achieved with preservation of hearing and facial nerve function, both in the immediate and long-term periods. This article provides an overview of the background and indications for the procedure, a description of the operative protocol, and a summary of the literature on postoperative hearing outcomes.

Assessment of Gender Disparities in Short-Term and Long-Term Outcomes Following Posterior Fossa Tumor Resection

Introduction

The analysis of social determinants of health (SDOH) across different surgical populations is critical for the identification of health disparities and the development risk mitigation strategies among vulnerable patients. Research into the impact of gender on neurosurgical outcomes remains limited. The aim of the present study was to assess the effect of gender on outcomes, in a matched sample, following posterior fossa tumor resection, a high-risk neurosurgical procedure.

Methods

Two hundred seventy-eight consecutive patients undergoing posterior fossa tumor resection over a six-year period (June 07, 2013, to April 29, 2019) at a single academic medical system were retrospectively evaluated. Short-term outcomes included 30- and 90-day rates of emergency department (ED) visit, readmission, reoperation, and mortality. Long-term outcomes included mortality and reoperation for the duration of follow-up. Firstly, male and female patients in the entire pre-match sample were compared. Thereafter, coarsened exact matching was employed to control for confounding variables, matching male and female patients on key demographic factors - including history of prior surgery, median household income, and race, amongst others - and outcome comparison was repeated.

Results

In both the entire pre-match sample and matched cohort analyses, no significant differences in adverse postsurgical events were discerned between the female and male patients when evaluating 30-day or 90-day rates of ED visit, readmission, reoperation, and mortality. There were also no differences in reoperation or mortality for the duration of follow-up.

Conclusion

Gender does not appear to impact short- or long-term outcomes following posterior fossa tumor resection. As such, risk assessment and mitigation strategies in this population should focus on other SDOH. Further studies should assess the role of other SDOH within this population.

Extended Middle Cranial Fossa Approach for Placement of Auditory Brainstem Implants

OBJECTIVE

Traditionally, auditory brainstem implants (ABIs) have been placed via the translabyrinthine or retrosigmoid approaches. In select patients, a modified extended middle cranial fossa (xMCF) approach with tentorial ligation may be advantageous for vestibular schwannoma (VS) resection and auditory rehabilitation. This manuscript describes the application of this modification of the MCF approach for simultaneous VS resection and ABI placement.

PATIENTS

Patients with neurofibromatosis type 2, profound bilateral sensorineural hearing loss, single functioning sigmoid/jugular venous system, and giant (>4 cm) VS.

INTERVENTIONS

Simultaneous VS resection and ABI placement via a modified xMCF approach with tentorial ligation.

MAIN OUTCOME MEASURES

Extent of tumor removal and brainstem decompression, access to lateral recess of the fourth ventricle, functional hearing improvement, surgical complications.

RESULTS

Two patients met indications and underwent surgery. There were no immediate or delayed surgical complications. Both had subtotal tumor removal with significant decompression of the brainstem and ABI placement. One patient achieved voice and environmental sound awareness at 35 to 55 dbHL across frequencies. The second patient presented with failure to thrive and multiple lower cranial neuropathies in addition to the above-listed indications. She was hospitalized multiple times after surgery due to failure to thrive and recurrent aspiration pneumonia. Her device was never activated, and she expired 1 year after surgery.

CONCLUSIONS

The xMCF with tentorial ligation is an additional approach for tumor resection and ABI placement in selected patients with neurofibromatosis type 2. Future studies will further define when this approach is most applicable as well as the challenges and pitfalls.

Adaptation of the Standardized Hearing Outcomes Scattergram to Hearing Preservation in Cochlear Implantation

OBJECTIVE

Encourage adaptation of a standardized format for reporting hearing preservation outcomes in cochlear implantation (CI).

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary referral center.

PATIENTS

One hundred seventy-eight postlingually deafened adults with bilateral SNHL and a preoperative low-frequency pure-tone average (LFPTA) 80 dB HL or better at 125, 250, and 500 Hz in the ear to be implanted.

INTERVENTIONS

Subjects underwent unilateral CI from 2013 to 2019 at a large referral center. Pre- versus postoperative LPFTA was used to generate a scattergram.

MAIN OUTCOMES MEASURES

Pre- versus postoperative activation LPFTA, percentage of patients fit with electric and acoustic stimulation, scattergram plot.

RESULTS

Average postoperative LFPTA was 68.6 dB HL (range 18-68) compared with 48.7 dB (range 5-80), preoperatively. At activation, the average LFPTA shift at CI activation was 20.5 dB HL (range 0-60) and 83.5% (n = 137) patients had hearing preserved, of whom 41.6% were fit with electric and acoustic stimulation throughout the study period. The scattergram successfully illustrates the distribution and number of patients with their respective audiometric outcomes.

CONCLUSIONS

The scattergram developed for reporting hearing outcomes in clinical trials is highly adaptable to reporting hearing preservation results in cochlear implant surgery. It represents a transparent and accessible option for reporting outcomes that can be used as a consistent format to allow for interstudy comparison and future meta-analysis.

A New Bony Anatomical Landmark for Lateral Skull Base Surgery

BACKGROUND AND OBJECTIVE

The aim of the study was to propose a new bony landmark, point O, which is the junction point of the temporosphenoid suture and the infratemporal ridge; this landmark may improve the identification and preservation of neurovascular structures when approaches are used to access the middle cranial fossa in lateral skull base tumor surgeries.

METHODS

Fifteen cadaveric heads were measured for anatomical analysis. Related surgical landmarks were studied using the Destroscope virtual reality system and during the dissection procedures, and the results were analyzed and compared.

RESULTS

From the perspective of the middle skull base, the radial lines from point O to the interior point of the superior orbital fissure, foramen rotundum, foramen ovale, and foramen spinosum are approximately equal in length, with an average length of 23.22 mm, and the above 5 points form a sector with an angle of 66.07° and an area of 310.71 mm.

CONCLUSIONS

Identification of point O as a landmark for lateral skull base surgery when other landmarks are not recognizable optimizes patient safety and surgeon confidence during complicated operations. The interior points of the superior orbital fissure, foramen rotundum, foramen ovale, and foramen spinosum are distributed on the arc of a circle whose center is point O. The sector formed by the above 5 points is not only a crucial area for the communication of lesions between the middle skull base and the infratemporal fossa but also a safe avenue through which to remove skull base lesions.

Outcomes of Transzygomatic Middle Cranial Fossa Approach for Skull Base Tumors-A Single Institutional Experience

Objective  This study aimed to evaluate surgical outcomes after transzygomatic middle cranial fossa (MCF) (TZ-MCF) approach for tumor control in patients with large skull base lesions involving the MCF and adjacent sites. Setting  This study was done at the tertiary skull base center. Design  This is a retrospective case series. Main Outcome Measures  The main outcome measures were tumor control (recurrence), new-onset cranial neuropathies, facial nerve and audiometric outcomes, cerebrospinal fluid (CSF) leak, and wound complications. Results  Sixteen patients were identified with a median age of 45 years (range: 20-72). The mean maximum tumor dimension was 5.49 cm (standard deviation [SD]: 1.2, range: 3.1-7.3) and the mean tumor volume was 28.5 cm ³ (SD: 18.8, range: 2.9-63.8). Ten (62.5%) tumors were left sided. The most common pathology encountered was meningioma ( n  = 7) followed by chondrosarcoma ( n  = 4). Mean follow-up was 36.3 (SD: 26.9) months. Gross total resection or near total resection was achieved in nine (56.2%) and planned subtotal resection was used in seven (43.7%). Postoperative additional new cranial nerve (CN) deficits included CN V ( n  = 1), CN III ( n  = 2), CN VI ( n  = 1), and CN X ( n  = 1). Major neurological morbidity (hemiplegia) was encountered in two patients with resolution. There were no cases of CSF leak, meningitis, hemorrhage, seizures, aphasia, or death. There was no recurrence or regrowth of residual tumor. Facial nerve function was preserved in all but one patient (House-Brackmann grade 2). Conclusion  Various skull base tumors involving MCF with extension to adjacent sites can be successfully resected using the TZ-MCF approach in a multidisciplinary fashion. This approach yields optimal exposure and permits excellent tumor control with acceptable CN and neurological morbidity.

Ultra Long-Term Audiometric Outcomes in the Treatment of Vestibular Schwannoma With the Middle Cranial Fossa Approach

OBJECTIVE

Define the long-term audiometric outcomes of vestibular schwannomas treated using the middle cranial fossa (MCF) approach.

STUDY DESIGN

Retrospective records review.

SETTING

University-based tertiary referral center.

PATIENTS

Patients undergoing treatment of small vestibular schwannomas using the MCF approach.

INTERVENTION(S)

MCF exposure and treatment of small vestibular schwannomas.

MAIN OUTCOME MEASURE(S)

Demographic and audiometric variables were assessed.

RESULTS

Thirteen subjects demonstrated audiometric data for review. The average time between surgery and the most recent audiometric testing was 14 years (range 10-18 yr). The mean baseline pure-tone average (PTA) was 36 dB HL and the most recent PTA was 59 dB HL in the operated ear. The mean baseline PTA was 16 dB HL and the most recent PTA was 37 dB HL in the nonoperated ear. The mean change from baseline to most recent follow-up was a threshold elevation of 22 and 19 dB HL in the operated and nonoperated ears, respectively. The mean baseline speech discrimination score (SDS) was 83% and the most recent SDS was 73% in the operated ear. The mean baseline SDS was 98% and the most recent SDS was 94% in the nonoperated ear. The mean changes from baseline to most recent follow-up were 10 and 0% SDS depression in the operated and nonoperated ears, respectively. The rates of changes in PTA and SDS were not statistically different between the operated and nonoperated ears.

CONCLUSIONS

Surgically preserved hearing is maintained in the majority of patients more than 10 years following surgery. PTA and SDS changes were similar between the ipsilateral and contralateral ears.

Comprehensive review of the extended middle cranial fossa approach

PURPOSE OF REVIEW

To review the current literature on the extended middle cranial fossa (xMCF) approach and to provide a comprehensive description of the relevant anatomy, indications, surgical technique, results, and complications.

RECENT FINDINGS

The xMCF approach expands the surgical exposure provided by the sMCF approach, allowing access to the internal auditory canal, cerebellopontine angle, prepontine cistern, anterior petrous apex, petrous carotid artery, Meckel's cave, cavernous sinus, mid and upper clivus, and posterior lesions approaching the jugular foramen. Preservation of serviceable hearing is possible with success rates approximating 50% in vestibular schwannoma and meningioma resection, and facial nerve outcome is excellent.

SUMMARY

The xMCF is an important approach for difficult to access lesions that additionally offers the possibility of hearing preservation. This approach is also useful for vascular lesions, auditory brainstem implantation, and lesions of mid-brainstem.

Surgical Management of Tumors Involving Meckel's Cave and Cavernous Sinus: Role of an Extended Middle Fossa and Lateral Sphenoidectomy Approach

OBJECTIVE

To study the indications and outcomes of lateral sphenoidectomy as part of a combined skull base approach in the treatment of tumors involving Meckel's cave (MC) and cavernous sinus (CS).

STUDY DESIGN

Retrospective patient series.

SETTING

Tertiary referral center.

PATIENTS

Twenty-two consecutive patients (mean age: 45 yr, range: 16-76) who underwent transzygomatic, extended middle fossa approaches for tumors involving MC and CS.

INTERVENTIONS

Surgical access to MC and CS was achieved via extended middle fossa, trans-clinoid approach. Lateral sphenoidectomy was defined as drill-out of the greater sphenoid wing lateral to foramen rotundum and ovale, decompression of superior orbital fissure, and removal of anterior clinoid process. Reconstruction was achieved using combination of autologous and synthetic materials. Eleven patients (50%) received adjuvant radiation.

MAIN OUTCOME MEASURES AND RESULTS

Tumor pathologies included meningioma (16 patients), epidermoid cyst (2), trigeminal schwannoma (2), invasive pituitary adenoma (1), and chondrosarcoma (1). Mean (range) preoperative tumor size was 4.0 cm (1.3-9). Mean (range) length of follow-up was 4 years (range 0.1-10). Overall tumor control and gross total resection were achieved in 95 and 23% of patients, respectively. Lateral sphenoidectomy was performed in 16 patients (73%) for enhanced surgical access and/or tumor extension to the infratemporal fossa (6 patients). Postoperatively, cranial nerve deficits occurred in 12 (55%) patients (V-9 patients; III, IV, or VI-4; VII-2; VIII-2). Cerebrospinal fluid leak and hydrocephalus occurred in two and four patients, respectively.

CONCLUSION

In combination with middle fossa-based approaches to tumors involving MC and CS, lateral sphenoidectomy may play a viable role in tumor access and control.