Middle Fossa Approach for Resection of Vestibular Schwannomas: A Decade of Experience

2018 ◽  
Vol 16 (2) ◽  
pp. 147-158 ◽  
Author(s):  
Jennifer A Kosty ◽  
Shawn M Stevens ◽  
Yair M Gozal ◽  
Vincent A DiNapoli ◽  
Smruti K Patel ◽  
...  
Keyword(s):  
Facial Nerve ◽  
Tumor Size ◽  
Pure Tone ◽  
Vestibular Schwannomas ◽  
Nerve Function ◽  
Facial Nerve Function ◽  
Pure Tone Average ◽  
Class A ◽  
The Mean

AbstractBACKGROUNDThe middle cranial fossa (MCF) approach is a challenging surgical technique for the resection of small and intermediate sized, primarily intracanalicular, vestibular schwannomas (VS), with the goal of hearing preservation (HP).OBJECTIVETo describe a decade-long, single institutional experience with the MCF approach for resection of VS.METHODSThis is a retrospective cohort study of 63 patients who underwent the MCF approach for resection of VS from 2006 to 2016. Audiometric data included pure-tone average (PTA), low-tone pure-tone average (LtPTA), word recognition score, and American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) hearing classification at presentation and follow-up. Patients with postoperative serviceable (AAO-HNS class A-B) and/or useful (AAO-HNS class A-C) hearing were compared to those without HP. Facial nerve function was assessed using the House–Brackmann scale.RESULTSThe mean age and duration of follow-up were 50 ± 13 yr and 21 ± 21 mo, respectively. The mean tumor size was 10 ± 4 mm. The serviceable and usable HP rates were 54% and 50%, respectively. Some residual hearing was preserved in 71% of patients. Large tumor size (P = .05), volume (P = .03), and extrameatal tumor extension (P = .03) were associated with poor audiometric outcomes. The presence of a fundal fluid cap (P = .01) was a favorable finding. At definitive testing, LtPTA was significantly better preserved than traditional PTA (P = .01). Facial nerve outcomes, tumor control rates, and durability of audiometric outcomes were excellent. 47% of patients pursued aural rehabilitation.CONCLUSIONIn our series, the MCF approach for VS provided excellent rates of tumor and facial nerve function, with durable serviceable HP.

Sporadic unilateral vestibular schwannoma in the pediatric population

2009 ◽  
Vol 4 (2) ◽  
pp. 125-129 ◽  
Author(s):  
Brian P. Walcott ◽  
Ganesh Sivarajan ◽  
Bronislava Bashinskaya ◽  
Douglas E. Anderson ◽  
John P. Leonetti ◽  
...  
Keyword(s):  
Facial Nerve ◽  
Tumor Size ◽  
Pediatric Population ◽  
Neurofibromatosis Type ◽  
Neurofibromatosis Type 2 ◽  
Nerve Function ◽  
Facial Nerve Function ◽  
Duration Of Symptoms

Object Vestibular schwannomas (VSs) are rare in the pediatric population. Most often, these lesions manifest as a bilateral disease process in the setting of neurofibromatosis Type 2. Even in the absence of additional clinical diagnostic criteria, the presentation of a unilateral VS in a young patient may be a harbinger of future penetrance for this hereditary tumor syndrome. Methods The authors retrospectively reviewed the charts of a cohort of 7 patients who presented with apparently sporadic, unilateral VSs. These patients had previously undergone surgery via translabyrinthine, retrosigmoid, or combined approaches. Clinical outcomes were reviewed with emphasis on facial nerve function and follow-up for signs and symptoms of a heritable disorder. Results All patients underwent microsurgical resection in a multidisciplinary effort by the senior authors. The average tumor size was 4.57 cm, with an average duration of symptoms prior to definitive diagnosis of 31.2 months. The tumor size at the time of presentation followed a trend different from reports in adults, while the duration of symptoms did not. At a follow-up average of 6.3 years (range 1–12 years), 100% of patients demonstrated good facial function (House-Brackmann Grade I or II). No patient in this cohort demonstrated symptoms, objective signs, or genetic analysis indicating the presence of neurofibromatosis Type 2. Conclusions Diagnosis and management of sporadic, unilateral VSs in children is complicated by clinical presentations and surgical challenges unique from their adult counterparts. Careful consideration should be given to a heritable genetic basis for sporadic unilateral VS in the pediatric population. Results of genetic testing do not preclude the necessity for long-term follow-up and systemic investigation. In patients who present with large tumors, preliminary experience leads the authors to suggest that a combined retrosigmoid-translabyrinthine approach offers the greatest opportunity for preservation of facial nerve function.

Intended Near-Total Removal of Koos Grade IV Vestibular Schwannomas: Reconsidering the Treatment Paradigm

Neurosurgery ◽  
2017 ◽  
Vol 82 (2) ◽  
pp. 202-210 ◽  
Author(s):  
Daniel Walter Zumofen ◽  
Tommaso Guffi ◽  
Christian Epple ◽  
Birgit Westermann ◽  
Anna-Katharina Krähenbühl ◽  
...  
Keyword(s):  
Facial Nerve ◽  
Tumor Volume ◽  
Residual Tumor ◽  
Extent Of Resection ◽  
Vestibular Schwannomas ◽  
Facial Nerve Function ◽  
Total Removal ◽  
Treatment Paradigm ◽  
The Mean

Abstract BACKGROUND The goals of treating Koos grade IV vestibular schwannomas are to relieve brainstem compression, preserve or restore neurological function, and achieve long-term tumor control while minimizing tumor- and treatment-related morbidity. OBJECTIVE To propose a treatment paradigm involving the intentional near-total removal of Koos grade IV vestibular schwannomas, in which a small amount of residual tumor is not dissected off the cisternal portion of the facial nerve. Patients are then followed by a wait-and-scan approach. Any subsequent volumetric progression of the residual tumor is treated with radiosurgery. METHODS This is a case series of 44 consecutive unselected patients who underwent intended near-total resection of a Koos grade IV vestibular schwannoma through a retrosigmoid approach from January 2009 to December 2015. Pre- and postoperative volumetric analyses were performed on routine magnetic resonance imaging sequences (constructive interference in steady state and gadolinium-enhanced T1-weighted sequence). RESULTS The mean preoperative tumor volume was 10.9 cm3. The mean extent of resection was 89%. At the last clinical follow-up, facial nerve function was good [House and Brackmann (HB) I-II] in 89%, fair (HB III) in 9%, and poor (HB IV-VI) in 2% of the patients. At the last radiological follow-up, the residual tumor had become smaller or remained the same size in 84% of patients. Volumetric progression was negatively correlated with the original extent of resection and positively correlated with postoperative residual tumor volume (P = .01, P < .001, respectively). CONCLUSION Intended near-total removal results in excellent preservation of facial nerve function and has a low recurrence rate. Any progressive residual tumor may be treated by radiosurgery.

Near Total Versus Gross Total Resection of Large Vestibular Schwannomas: Facial Nerve Outcome

2020 ◽  
Vol 19 (4) ◽  
pp. 414-421
Author(s):  
Julia R Schneider ◽  
Amrit K Chiluwal ◽  
Orseola Arapi ◽  
Kevin Kwan ◽  
Amir R Dehdashti
Keyword(s):  
Facial Nerve ◽  
Significant Risk ◽  
Retrospective Chart Review ◽  
Gross Total Resection ◽  
Vestibular Schwannomas ◽  
Primary Data ◽  
Nerve Function ◽  
Facial Nerve Function ◽  
Total Resection

Abstract BACKGROUND Large vestibular schwannomas (VSs) with brainstem compression are generally reserved for surgical resection. Surgical aggressiveness must be balanced with morbidity from cranial nerve injury. The purpose of the present investigation is to evaluate the clinical presentation, management modality, and patient outcomes following near total resection (NTR) vs gross total resection (GTR) of large VSs. OBJECTIVE To assess facial nerve outcome differences between GTR and NTR patient cohorts. METHODS Between January 2010 and March 2018, a retrospective chart review was completed to capture patients continuously who had VSs with Hannover grades T4a and T4b. NTR was decided upon intraoperatively. Primary data points were collected, including preoperative symptoms, tumor size, extent of resection, and postoperative neurological outcome. RESULTS A total of 37 patients underwent surgery for treatment of large and giant (grade 4a and 4b) VSs. Facial nerve integrity was preserved in 36 patients (97%) at the completion of surgery. A total of 27 patients underwent complete resection, and 10 had near total (>95%) resection. Among patients with GTR, 78% (21/27) had House-Brackmann (HB) grade I-II facial nerve function at follow-up, whereas 100% (10/10) of the group with NTR had HB grade I-II facial nerve function. Risk of meningitis, cerebrospinal fluid leak, and sinus thromboses were not statistically different between the 2 groups. There was no stroke, brainstem injury, or death. The mean follow-up was 36 mo. CONCLUSION NTR seems to offer a benefit in terms of facial nerve functional outcome compared to GTR in surgical management of large VSs without significant risk of recurrence.

Medial acoustic neuromas: clinical and surgical implications

2014 ◽  
Vol 120 (5) ◽  
pp. 1095-1104 ◽  
Author(s):  
Ian F. Dunn ◽  
Wenya Linda Bi ◽  
Kadir Erkmen ◽  
Paulo A. S. Kadri ◽  
David Hasan ◽  
...  
Keyword(s):  
Facial Nerve ◽  
Hearing Preservation ◽  
Growth Patterns ◽  
Maximum Diameter ◽  
Nerve Function ◽  
Facial Nerve Function ◽  
Class A ◽  
Acoustic Neuromas ◽  
Facial Function

Object Medial acoustic neuroma is a rare entity that confers a distinct clinical syndrome. It is scarcely discussed in the literature and is associated with adverse features. This study evaluates the clinical and imaging features, pertinent surgical challenges, and treatment outcome in a large series of this variant. The authors postulate that the particular pathological anatomy with its arachnoidal rearrangement has a profound implication on the surgical technique and outcome. Methods The authors conducted a retrospective analysis of 52 cases involving 33 women and 19 men who underwent resection of medial acoustic neuromas performed by the senior author (O.A.) over a 20-year period (1993–2013). Clinical, radiological, and operative records were reviewed, with a specific focus on the neurological outcomes and facial nerve function and hearing preservation. Intraoperative findings were analyzed with respect to the effect of arachnoidal arrangement on the surgeon's ability to resect the lesion and the impact on postoperative function. Results The average tumor size was 34.5 mm (maximum diameter), with over 90% of tumors being 25 mm or larger and 71% being cystic. Cerebellar, trigeminal nerve, and facial nerve dysfunction were common preoperative findings. Hydrocephalus was present in 11 patients. Distinguishing intraoperative findings included marked tumor adherence to the brainstem and frequent hypervascularity, which prompted intracapsular dissection resulting in enhancement on postoperative MRI in 18 cases, with only 3 demonstrating growth on follow-up. There was no mortality or major postoperative neurological deficit. Cerebrospinal fluid leak was encountered in 7 patients, with 4 requiring surgical repair. Among 45 patients who had intact preoperative facial function, only 1 had permanent facial nerve paralysis on extended follow-up. Of the patients with preoperative Grade I–II facial function, 87% continued to have Grade I–II function on follow-up. Of 10 patients who had Class A hearing preoperatively, 5 continued to have Class A or B hearing after surgery. Conclusions Medial acoustic neuromas represent a rare subgroup whose site of origin and growth patterns produce a distinct clinical presentation and present specific operative challenges. They reach giant size and are frequently cystic and hypervascular. Their origin and growth pattern lead to arachnoidal rearrangement with marked adherence against the brainstem, which is critical in the surgical management. Excellent surgical outcome is achievable with a high rate of facial nerve function and attainable hearing preservation. These results suggest that similar or better results may be achieved in less complex tumors.

The behavior of residual tumors and facial nerve outcomes after incomplete excision of vestibular schwannomas

2014 ◽  
Vol 120 (6) ◽  
pp. 1278-1287 ◽  
Author(s):  
Zhengnong Chen ◽  
Sampath Chandra Prasad ◽  
Filippo Di Lella ◽  
Marimar Medina ◽  
Enrico Piccirillo ◽  
...  
Keyword(s):  
Facial Nerve ◽  
Residual Tumor ◽  
Vestibular Schwannomas ◽  
Subtotal Resection ◽  
Nerve Function ◽  
Facial Nerve Function ◽  
Incomplete Excision ◽  
Kaplan Meier ◽  
Tumor Regrowth

Object The authors evaluated the behavior of residual tumors and facial nerve outcomes after incomplete excision of vestibular schwannomas (VSs). Methods The case records of all patients who underwent surgical treatment of VSs were analyzed. All patients in whom an incomplete excision had been performed were analyzed. Incomplete excision was defined as near-total resection (NTR), subtotal resection (STR), and partial resection (PR). Tumors in the NTR and STR categories were followed up with a wait-and-rescan approach, whereas the tumors in the PR category were subjected to a second-stage surgery and were excluded from this series. All patients included in the study underwent baseline MRI at the 3rd and 12th postoperative months, and repeat imaging was subsequently performed every year for 7–10 years postoperatively or as indicated clinically. Preoperative and postoperative facial function was noted. Results Of the 2368 patients who underwent surgery for VS, 111 patients who had incomplete excisions of VSs were included in the study. Of these patients, 73 (65.77%) had undergone NTR and 38 (34.23%) had undergone STR. Of the VSs, 62 (55.86%) were cystic and 44 (70.97%) of these cystic VSs underwent NTR. The residual tumor was left behind on the facial nerve alone in 62 patients (55.86%), on the facial nerve and vessels in 2 patients (1.80%), on the facial nerve and brainstem in 15 patients (13.51%), and on the brainstem alone in 25 patients (22.52%). In the 105 patients with normal preoperative facial nerve function, postoperative facial nerve function was House-Brackmann (HB) Grades I and II in 51 patients (48.57%), HB Grade III in 34 patients (32.38%), and HB Grades IV–VI in 20 patients (19.05%). Seven patients (6.3%) showed evidence of tumor regrowth on follow-up MRI. All 7 patients (100%) who showed evidence of tumor regrowth had undergone STR. No patient in the NTR group exhibited regrowth. The Kaplan-Meier plot demonstrated a 5-year tumor regrowth-free survival of 92%, with a mean disease-free interval of 140 months (95% CI 127–151 months). The follow-up period ranged from 12 to 156 months (mean 45.4 months). Conclusions The authors' report and review of the literature show that there is undoubtedly merit for NTR and STR for preservation of the facial nerve. On the basis of this they propose an algorithm for the management of incomplete VS excisions. Patients who undergo incomplete excisions must be subjected to follow-up MRI for a period of at least 7–10 years. When compared with STR, NTR via an enlarged translabyrinthine approach has shown to have a lower rate of regrowth of residual tumor, while having almost the same result in terms of facial nerve function.

Durability of hearing preservation after microsurgical treatment of vestibular schwannoma using the middle cranial fossa approach

2013 ◽  
Vol 119 (1) ◽  
pp. 131-138 ◽  
Author(s):  
Anthony C. Wang ◽  
Steven B. Chinn ◽  
Khoi D. Than ◽  
H. Alexander Arts ◽  
Steven A. Telian ◽  
...  
Keyword(s):  
Facial Nerve ◽  
Hearing Preservation ◽  
Middle Cranial Fossa ◽  
Nerve Function ◽  
Facial Nerve Function ◽  
Class A ◽  
Class D ◽  
Class B ◽  
Class C

Object The middle cranial fossa (MCF) approach is a microsurgical technique described as a primary option in the treatment of small, intracanalicular schwannomas involving the eighth cranial nerve. Excellent rates of complete tumor resection, hearing preservation, preservation of facial nerve function, and low complication rates have been reproduced using this technique. However, the durability of hearing preservation attained using the various treatment options has not been adequately assessed. The purpose of this study was to evaluate the durability of long-term hearing preservation in patients with vestibular schwannoma (VS) treated via the MCF approach. The authors hypothesize that hearing preservation in these patients will prove to be durable years after treatment in a high percentage of cases. Methods Retrospective medical chart review was performed in 103 consecutive patients undergoing resection of VS via a modified MCF approach between 1999 and 2008. Patients in whom surgical goals were gross-total resection and hearing preservation were included. Preoperative and postoperative hearing assessment was performed using standard audiometric testing, and classified according to American Academy of Otolaryngology–Head and Neck Surgery (AAO-HNS) guidelines as a primary outcome measure. Outcomes and neurological complications initially, and at 1, 3, and 5 years following operation were analyzed. Results Initial hearing preservation rates were in keeping with the best previously published results. At initial postoperative audiometric follow-up, of the patients presenting with Class A hearing, 67% remained Class A, 17% were Class B, 1% were Class C, and 15% were Class D. Of patients presenting with Class B hearing, 24% were Class A, 53% remained Class B, 6% were Class C, and 18% were Class D. Of patients presenting with Class C hearing, 100% remained Class C. To assess the durability of hearing preservation in our patients, the authors evaluated hearing function at regular intervals after the initial postoperative audiometric follow-up. Audiometric data were available for 56 patients at 5-year follow-up. Of the 20 patients with Class A hearing at initial postoperative follow-up with 5-year follow-up, 13 (65%) remained Class A, 6 (30%) were Class B, and 1 (5%) was Class C. Of the 12 patients with Class B hearing at initial postoperative follow-up with 5-year follow-up, 4 (33%) were Class A, 4 (33%) remained Class B, and 4 (33%) were Class C. Of the 3 patients with Class C hearing at initial postoperative follow-up with 5-year follow-up, all 3 (100%) remained Class C. Conclusions A majority of patients with preserved hearing following the MCF approach for treatment of VS experience durability of their preserved hearing at 5-year follow-up. The initial AAO-HNS classification was preserved in 13 (65%) of the 20 patients who had Class A hearing at 5 years, and in 8 (67%) of the 12 who had Class B hearing at 5 years. Overall, a decline in AAO-HNS classification was noted in 15% of patients with preserved Class A hearing, and in 33% of those with preserved Class B hearing. Facial nerve function was preserved in 91% of cases. Superior hearing preservation as well as good outcomes in facial nerve function and few serious complications can be accomplished using the MCF approach for resection of small VSs.

scholarly journals Extra-Arachnoidal Dissection for Excision of Giant Vestibular Schwannomas: Improved Facial Nerve Preservation

Neurosurgery ◽  
2019 ◽  
Vol 66 (Supplement_1) ◽  
Author(s):  
Sunil K Gupta
Keyword(s):  
Facial Nerve ◽  
Vestibular Schwannomas ◽  
Nerve Function ◽  
Total Excision ◽  
Facial Nerve Function ◽  
Nerve Preservation ◽  
Group A ◽  
Grade 3 ◽  
Group B

Abstract INTRODUCTION Surgical excision of giant vestibular schwannomas with preservation of facial nerve function remains a challenge. A modified surgical technique using an extra-arachnoid plane of dissection and limited meatal drilling is described here with the goal of improving the rated of functional preservation of facial nerve. METHODS The clinical material was analyzed for two groups: Group A patients of giant vestibular schwannomas operated between 2002 and 2009 with the “standard” surgical technique, Group B- patients of giant vestibular schwannomas operated between 2009 and 2015 using the new technique of pure extra-arachnoid dissection and limited meatal drilling. RESULTS Group A: Of the 115 patients in this group, total excision was possible in 103 (89.5%), near total excision in 7 (6%) and partial excision in 5 (4.3%) patients. Anatomical preservation of 7th nerve was achieved in 87.8% of patients. House and Brackman grade 1 and grade 2 facial nerve function was present in 68 (59.1%) patients, grade 3 in 10 (8.7%), grades 4 and 5 in 11 (9.6%), and 26 (22.6%) had grade 6 facial nerve involvement. Group B: Of the 127 patients operated by this technique, details and long term follow-up was available for 98 patients. Total excision was achieved in 70 (71.4%) patients, near total excision in 9 (9.2%), and subtotal excision in 19 (19.4%) cases. Four patients had repeat surgery and 14 patients underwent gamma knife radiosurgery. At follow-up, 78 (79.5%) patients had grade 1 and 2 facial nerve involvement, while 20 (20.4%) patients continued to have a poor function (grade 3-5). CONCLUSION Extra-arachnoid dissection and limited meatal drilling resulted in an improved rate of functional facial nerve preservation.

scholarly journals Facial nerve preservation in stereotactic radiosurgery of tumors of the cerebellopontine cistern

2021 ◽  
Vol 23 (2) ◽  
pp. 57-65
Author(s):  
S. R. Ilyalov ◽  
K. M. Kvashnin ◽  
K. E. Medvedeva ◽  
A. A. Baulin ◽  
O. G. Lepilina ◽  
...  
Keyword(s):  
Facial Nerve ◽  
Tumor Volume ◽  
Cranial Nerves ◽  
Nerve Function ◽  
Facial Nerve Function ◽  
Facial Paresis ◽  
Previous Surgery ◽  
Study Objective ◽  
The Mean

Introduction. Surgery has traditionally remained the main treatment for tumors of the cerebellopontine cistern but is associated with high risks of dysfunction of the cranial nerves. Radiosurgery is usually performed both as an adjuvant treatment and as an independent option.The study objective is to assess the safety of routine use of radiosurgery to preserve facial nerve function in the treatment of tumors of different origins located in the cerebellopontine cistern.Materials and methods. Since March 2018 to March 2020 there were 145 patients with tumors of cerebellopontine cistern (CPC) at the Center for High-Precision Radiology. Vestibilar schwannomas were detected in 116 (80 %) patients, in 37 cases - relapses or remains after surgery. The 22 patients had meningiomas, 6 after open surgery (WHO I). Trigeminal schwannomas - in 3 patients, facial schwannomas - in 2, jugular schwannomas - in 1 and metastasis of prostate cancer - in 1. 31 patients had facial paresis of different degrees after previous surgery. Among non-operated patients, facial paresis before radiosurgery was observed in only 1 patient. Radiosurgery was performed using the Leksell Gamma Knife Perfexion, the mean marginal dose was 12.2 Gy (11-15 Gy), the mean tumor volume was 3.98 cm3 (0.06-17.47 cm3).Results. Follow-up was performed in 85 patients. The mean follow-up was 359.3 days (91-776), the median follow-up was 367 days. Reduction of the tumor volume was detected in 27 patients, stabilization of the process in 15. The average decrease was 23.9 % (95 % CI 16.8-31.0 %). Transient postirradiation increase was observed in 30 patients only in the group of schwannomas and mean tumor volume increase was 53.7 % (95 % CI 38.5-68.9 %). In patients with previous surgery there were not cases of decline or regression facial paresis. Among patients who had not been operated on before radiosurgery, only in 1 case was the development of facial paresis (House-Brackman III) 5 months after irradiation, which amounted to 1.8 %. It should be especially noted that facial nerve function remained unchanged (House-Brackman I) in both patients with facial schwannomas. Also, not a single case of hemifacial spasm was identified.Conclusion. Radiosurgery of CPC tumors with a marginal dose from 12 to 15 Gy has a high degree of safety in relation to the facial nerve. This makes it possible to justify radiosurgery as alternative to traditional neurosurgical interventions.

scholarly journals Long-term facial nerve clinical evaluation following vestibular schwannoma surgery

2008 ◽  
Vol 66 (2a) ◽  
pp. 194-198 ◽  
Author(s):  
Rafaela Julia Batista Veronezi ◽  
Yvens Barbosa Fernandes ◽  
Guilherme Borges ◽  
Ricardo Ramina
Keyword(s):  
Facial Nerve ◽  
Vestibular Schwannoma ◽  
Tumor Size ◽  
Nerve Function ◽  
Facial Nerve Function ◽  
Significant Difference ◽  
Long Term Follow Up ◽  
Facial Function

BACKGROUND: Facial function is important in accompaniment of patients operated on vestibular schwannoma (VS). OBJETIVE: To evaluate long term facial nerve function in patients undergoing VS resection and to correlate tumor size and facial function in a long-term follow-up. METHOD: Transversal study of 20 patients with VS operated by the retrosigmoid approach. House-Brackmann Scale was used preoperatively, immediately after surgery and in a long-term follow-up. Student t test was applied for statistic analysis. RESULTS: In the immediate postoperative evaluation, 65% of patients presented FP of different grades. Improvement of facial nerve function (at least of one grade) occurred in 53% in the long-term follow-up. There was statistically significant difference in facial nerve outcome in long-term follow-up when tumor size was considered (p<0.05). Conclusion: The majority of patients had improvement of FP in a long-term follow-up and tumor size was detected to be a factor associated with the postoperative prognostic.

Defining clinically significant tumor size in vestibular schwannoma to inform timing of microsurgery during wait-and-scan management: moving beyond minimum detectable growth

2021 ◽  
pp. 1-9
Author(s):  
Robert J. Macielak ◽  
Katherine P. Wallerius ◽  
Skye K. Lawlor ◽  
Christine M. Lohse ◽  
John P. Marinelli ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Facial Nerve ◽  
Tumor Size ◽  
Optimal Size ◽  
Nerve Function ◽  
Facial Nerve Function ◽  
Class A ◽  
Microsurgical Resection ◽  
Size Threshold ◽  
Serial Mri

OBJECTIVE Detection of vestibular schwannoma (VS) growth during observation leads to definitive treatment at most centers globally. Although ≥ 2 mm represents an established benchmark of tumor growth on serial MRI studies, 2 mm of linear tumor growth is unlikely to significantly alter microsurgical outcomes. The objective of the current work was to ascertain where the magnitude of change in clinical outcome is the greatest based on size. METHODS A single-institution retrospective review of a consecutive series of patients with sporadic VS who underwent microsurgical resection between January 2000 and May 2020 was performed. Preoperative tumor size cutpoints were defined in 1-mm increments and used to identify optimal size thresholds for three primary outcomes: 1) the ability to achieve gross-total resection (GTR); 2) maintenance of normal House-Brackmann (HB) grade I facial nerve function; and 3) preservation of serviceable hearing (American Academy of Otolaryngology–Head and Neck Surgery class A/B). Optimal size thresholds were obtained by maximizing c-indices from logistic regression models. RESULTS Of 603 patients meeting inclusion criteria, 502 (83%) had tumors with cerebellopontine angle (CPA) extension. CPA tumor size was significantly associated with achieving GTR, postoperative HB grade I facial nerve function, and maintenance of serviceable hearing (all p < 0.001). The optimal tumor size threshold to distinguish between GTR and less than GTR was 17 mm of CPA extension (c-index 0.73). In the immediate postoperative period, the size threshold between HB grade I and HB grade > I was 17 mm of CPA extension (c-index 0.65). At the most recent evaluation, the size threshold between HB grade I and HB grade > I was 23 mm (c-index 0.68) and between class A/B and C/D hearing was 18 mm (c-index 0.68). Tumors within 3 mm of the 17-mm CPA threshold displayed similarly strong c-indices. Among purely intracanalicular tumors, linear size was not found to portend worse outcomes for all measures. CONCLUSIONS The probability of incurring less optimal microsurgical outcomes begins to significantly increase at 14–20 mm of CPA extension. Although many factors ultimately influence decision-making, when considering timing of microsurgical resection, using a size threshold range as depicted in this study offers an evidence-based approach that moves beyond reflexively recommending treatment for all tumors after detecting ≥ 2 mm of tumor growth on serial MRI studies.

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