Improved Recovery after Vestibular Schwannoma Excision with Intratympanic Gentamicin Prehabilitation.

OBJECTIVE: Translabyrinthine excision of a vestibular schwannoma is associated with acute vestibular failure. Preoperative intratympanic gentamicin (ITG) injections can improve objective balance function after surgery but its clinical benefits remain to be established. METHODS: Adult patients undergoing translabyrinthine removal of a vestibular schwannoma between January 2014 and February 2018 underwent preoperative vestibular function testing. Patients were divided in to 3 groups, those with vestibular function (VF) who received ITG injections, those with VF but did not receive ITG and those with no VF. Groups were compared according to degree of vertigo, length of stay, time to unassisted mobilization, and postoperative anti-emetic consumption. RESULTS: Forty six patients had ITG injections (Group 1), 7 had residual VF but refused treatment (Group 2), 21 had no VF (Group 3). Group 1 had a significant improvement in vertigo over time whereas groups 2 and 3 did not. There was a statistically significant 70% decrease in time to independent mobilization between Group 1 and other groups and a 19% decrease in length of stay in Group 1 compared to other groups although this did not reach statistical significance. Two patients had injection-related complications. Group 1 used less anti-emetics than other groups but this was not statistically significant. CONCLUSION: Preoperative intratympanic gentamicin injection with vestibular rehabilitation exercises is associated with less postoperative vertigo and earlier postoperative mobilization. There was reduced duration of hospitalization and decreased consumption of anti-emetic but not significantly so possibly because of low numbers of patients in the no treatment group. LEVEL OF EVIDENCE: 2 Laryngoscope, 2024.

Rationale for the Development of a Novel Clinical Grading Scale for Postoperative Facial Nerve Function: Results of a Multidisciplinary International Working Group.

OBJECTIVE: The objective of the current study was to present the results of an international working group survey identifying perceived limitations of existing facial nerve grading scales to inform the development of a novel grading scale for assessing early postoperative facial paralysis that incorporates regional scoring and is anchored in recovery prognosis and risk of associated complications. STUDY DESIGN: Survey. SETTING: A working group of 48 multidisciplinary clinicians with expertise in skull base, cerebellopontine angle, temporal bone, or parotid gland surgery. RESULTS: House-Brackmann grade is the most widely used system to assess facial nerve function among working group members (81%), although more than half (54%) agreed that the system they currently use does not adequately estimate the risk of associated complications, such as corneal injury, and confidence in interrater and intrarater reliability is generally low. Simplicity was ranked as the most important attribute of a novel postoperative facial nerve grading system to increase the likelihood of adoption, followed by reliability and accuracy. There was widespread consensus (91%) that the eye is the most critical facial region to focus on in the early postoperative setting. CONCLUSIONS: Members were invited to submit proposed grading systems in alignment with the objectives of the working group for subsequent validation. From these data, we plan to develop a simple, clinically anchored, and reproducible staging system with regional scoring for assessing early postoperative facial nerve function after surgery of the skull base, cerebellopontine angle, temporal bone, or parotid gland.

Changes in antimicrobial resistance in acute otitis media and otitis externa.

OBJECTIVES: Acute otitis media (AOM) and otitis externa (OE) are common ear infections which may warrant antibiotic therapy. For many infections, there is a rise in antimicrobial resistance, which is associated with treatment failure, morbidity, prolonged hospitalisation and mortality. This study aimed to identify longitudinal changes in microbiology and antimicrobial resistance in aural swabs taken from patients with AOM or OE. DESIGN: Retrospective observational analysis. SETTING: Aural samples processed at Manchester Medical Microbiology Partnership Laboratories between January 2008 and December 2018 were analysed to record organism isolated and antimicrobial sensitivity. PARTICIPANTS: Individual aural swabs from 7200 patients. MAIN OUTCOME MEASURES: Changes in the incidence of organisms and antimicrobial resistance between two time periods (2008-2012 and 2013-2018) were compared using the chi-squared test (alpha = 0.05). RESULTS: From 7200 swabs, 2879 (40%) were from children. The most frequently isolated organisms were Staphylococcus aureus (25%), Pseudomonas aeruginosa (24.4%), yeast (9.1%), mixed anaerobes (7.9%) and Haemophilus influenzae (6.1%). In children aged 0-4 years, H. influenzae had particularly high incidence (25%). Overall, the incidence of P. aeruginosa decreased significantly with time (p = 0.05). Isolates displaying resistance to one or more antimicrobial agents increased significantly in number in the second time period for P. aeruginosa (p = 0.04) and H. influenzae (p = 0.03). There was increased resistance to amoxicillin for P. aeruginosa (p = 0.01) and to erythromycin for H. influenzae (p < 0.01). CONCLUSION: Variations in type and frequency of organisms with increasing age likely result from differences in the preponderance of AOM compared to OE in children versus adults. We found increasing antimicrobial resistance for two organisms commonly isolated from AOM and OE infections, suggesting that aspects of current UK treatment practices and national recommendations may need to be revised.

The experience of auditory implant recipients undergoing magnetic resonance imaging: Factors associated with pain.

OBJECTIVE: Many patients with cochlear implants (CI) and auditory brainstem implants (ABI) require magnetic resonance imaging (MRI) following implantation. This study explores the patient experience of MRI, identifying factors associated with pain, and the effect of interventions designed to enhance comfort and safety. METHODS: A prospective observational case series from a tertiary referral unit. Tight head bandaging ± local anaesthetic injection (devices with non-MRI-compatible magnets) or observation alone (implants with MRI-compatible magnets) were employed for 1.5 T MRI of consecutive adult patients with CI or ABI without magnet removal. Pain was recorded via visual analogue scale (1 = no pain, 5 = extreme pain) at three time points; (1) baseline, (2) head bandage applied (3) during scanning. Patient age, device type, body area imaged and total scan time were recorded as variables, alongside adverse events. RESULTS: Data were collected for 227 MRI scans (34 patients with ABI, 32 with CI). In patients managed with bandaging, pain score after bandaging but prior to scanning (median 2.2) did not differ from pain during scanning (2.1), but both were significantly higher than baseline (1.4, both P ≤ 0.001). Scanning areas other than the head/cervical spine was associated with higher pain scores (P = 0.036). Pain during MRI differed between different manufacturers implants (P ≤ 0.001). Adverse events occurred in 8/227 scans (3.5%), none occurring with devices containing an MRI-compatible magnet. CONCLUSION: MRI scanning with auditory implant magnets in situ is safe and well tolerated by patients.

Genome-wide association analysis identifies a susceptibility locus for sporadic vestibular schwannoma at 9p21.

Vestibular schwannomas are benign nerve sheath tumours that arise on the vestibulocochlear nerves. Vestibular schwannomas are known to occur in the context of tumour predisposition syndromes NF2-related and LZTR1-related schwannomatosis. However, the majority of vestibular schwannomas present sporadically without identification of germline pathogenic variants. To identify novel genetic associations with risk of vestibular schwannoma development, we conducted a genome-wide association study in a cohort of 911 sporadic vestibular schwannoma cases collated from the neurofibromatosis type 2 genetic testing service in the north-west of England, UK and 5500 control samples from the UK Biobank resource. One risk locus reached genome-wide significance in our association analysis (9p21.3, rs1556516, P = 1.47 × 10-13, odds ratio = 0.67, allele frequency = 0.52). 9p21.3 is a genome-wide association study association hotspot, and a number of genes are localized to this region, notably CDKN2B-AS1 and CDKN2A/B, also referred to as the INK4 locus. Dysregulation of gene products within the INK4 locus have been associated with multiple pathologies and the genes in this region have been observed to directly impact the expression of one another. Recurrent associations of the INK4 locus with components of well-described oncogenic pathways provides compelling evidence that the 9p21.3 region is truly associated with risk of vestibular schwannoma tumorigenesis.

Cochlear Implantation in Neurofibromatosis Type 2: Experience From the UK Neurofibromatosis Type 2 Service.

OBJECTIVE: To review the outcomes of cochlear implants (CI) in patients with neurofibromatosis type 2 (NF2) in a large cohort, and identify factors associated with poor hearing benefit. STUDY DESIGN: Fifteen-year retrospective national observational case series. SETTING: United Kingdom regional NF2 multidisciplinary teams. PATIENTS: Consecutive patients with NF2 receiving a CI. INTERVENTIONS: CI for hearing rehabilitation. MAIN OUTCOME MEASURES: 1) Audiometric performance at 9 to 12 months after implantation using City University of New York (CUNY) sentence recognition score, and Bamford- Kowal-Bench (BKB) word recognition score in quiet (BKBq), and in noise (BKBn). 2) CI use at most recent review. RESULTS: Sixty four consecutive patients, median age 43 years, were included. Nine to 12 months mean audiometric scores were: CUNY 60.9%, BKBq 45.8%, BKBn 41.6%. There was no difference in audiometric outcomes between VS treatment modalities. At most recent review (median 3.6 years from implantation), 84.9% with device in situ/available data were full or part-time users. Between 9 and 12 months and most recent review there was an interval reduction in mean audiometric scores: CUNY -12.9%, BKBq -3.3%, BKBn -4.9%. Larger tumor size and shorter duration of profound hearing loss were the only variables associated with poorer audiometric scores. Tumor growth at the time of surgery was the only variable associated with CI non-use. Individual patient response was highly variable. CONCLUSIONS: CI can provide significant and sustained auditory benefits to patients with NF2 independent of tumor treatment modality, with the majority of those implanted becoming at least part-time users. Larger datasets are required to reliably assess the role of independent variables.

The utility of the exoscope compared to the operating microscope in simulated temporal bone surgery.

OBJECTIVE: To objectively assess the utility of an exoscope during simulated otological surgery. DESIGN: Cohort study. SETTING: Tertiary referral otolaryngology centre. PARTICIPANTS: Seven experienced otologists undertook simulated temporal bone surgery on plastic temporal bones using the Zeiss Kinevo microscope with both a microscope and exoscope facility. OUTCOME MEASURES: The utility of microscope and exoscope was compared using a Likert scale from 1 to 10 with and without PPE. Attributes assessed included image quality, depth perception, adequacy of view, exoscope positioning, surgeon comfort, surgeon safety and adequacy of image and protection for assistants and observers. RESULTS: The exoscope in 3D mode performed as well as or better than the microscope for image quality, field of view and manoeuvrability. It outperformed the microscope for compatibility with PPE, surgeon comfort and assistant/observer experience. It scored almost as highly as the microscope for depth perception. CONCLUSION: There is likely to be a learning curve but this initial assessment of the exoscope shows significant potential as an alternative to the operating microscope in otological surgery but with the advantage of allowing the use of appropriate PPE and better ergonomics for both surgeon and assistant/observer.

Sporadic vestibular schwannoma: a molecular testing summary.

OBJECTIVES: Cases of sporadic vestibular schwannoma (sVS) have a low rate of association with germline pathogenic variants. However, some individuals with sVS can represent undetected cases of neurofibromatosis type 2 (NF2) or schwannomatosis. Earlier identification of patients with these syndromes can facilitate more accurate familial risk prediction and prognosis. METHODS: Cases of sVS were ascertained from a local register at the Manchester Centre for Genomic Medicine. Genetic analysis was conducted in NF2 on blood samples for all patients, and tumour DNA samples when available. LZTR1 and SMARCB1 screening was also performed in patient subgroups. RESULTS: Age at genetic testing for vestibular schwannoma (VS) presentation was younger in comparison with previous literature, a bias resulting from updated genetic testing recommendations. Mosaic or constitutional germline NF2 variants were confirmed in 2% of patients. Pathogenic germline variants in LZTR1 were found in 3% of all tested patients, with a higher rate of 5% in patients <30 years. No pathogenic SMARCB1 variants were identified within the cohort. Considering all individuals who received tumour DNA analysis, 69% of patients were found to possess two somatic pathogenic NF2 variants, including those with germline LZTR1 pathogenic variants. CONCLUSIONS: Undiagnosed schwannoma predisposition may account for a significant minority of apparently sVS cases, especially at lower presentation ages. Loss of NF2 function is a common event in VS tumours and may represent a targetable common pathway in VS tumourigenesis. These data also support the multi-hit mechanism of LZTR1-associated VS tumourigenesis.

Incidence of mosaicism in 1055 de novo NF2 cases: much higher than previous estimates with high utility of next-generation sequencing.

PURPOSE: To evaluate the incidence of mosaicism in de novo neurofibromatosis 2 (NF2). METHODS: Patients fulfilling NF2 criteria, but with no known affected family member from a previous generation (n = 1055), were tested for NF2 variants in lymphocyte DNA and where available tumor DNA. The proportion of individuals with a proven or presumed mosaic NF2 variant was assessed and allele frequencies of identified variants evaluated using next-generation sequencing. RESULTS: The rate of proven/presumed mosaicism was 232/1055 (22.0%). However, nonmosaic heterozygous pathogenic variants were only identified in 387/1055 (36.7%). When variant detection rates in second generation nonmosaics were applied to de novo cases, we assessed the overall probable mosaicism rate to be 59.7%. This rate differed by age from 21.7% in those presenting with bilateral vestibular schwannoma <20 years to 80.7% in those aged ≥60 years. A mosaic variant was detected in all parents of affected children with a single-nucleotide pathogenic NF2 variant. CONCLUSION: This study has identified a very high probable mosaicism rate in de novo NF2, probably making NF2 the condition with the highest expressed rate of mosaicism in de novo dominant disease that is nonlethal in heterozygote form. Risks to offspring are small and probably correlate with variant allele frequency detected in blood.

Schwannomatosis: a genetic and epidemiological study.

OBJECTIVES: Schwannomatosis is a dominantly inherited condition predisposing to schwannomas of mainly spinal and peripheral nerves with some diagnostic overlap with neurofibromatosis-2 (NF2), but the underlying epidemiology is poorly understood. We present the birth incidence and prevalence allowing for overlap with NF2. METHODS: Schwannomatosis and NF2 cases were ascertained from the Manchester region of England (population=4.8 million) and from across the UK. Point prevalence and birth incidence were calculated from regional birth statistics. Genetic analysis was also performed on NF2, LZTR1 and SMARCB1 on blood and tumour DNA samples when available. RESULTS: Regional prevalence for schwannomatosis and NF2 were 1 in 126 315 and 50 500, respectively, with calculated birth incidences of 1 in 68 956 and 1 in 27 956. Mosaic NF2 causes a substantial overlap with schwannomatosis resulting in the misdiagnosis of at least 9% of schwannomatosis cases. LZTR1-associated schwannomatosis also causes a small number of cases that are misdiagnosed with NF2 (1%-2%), due to the occurrence of a unilateral vestibular schwannoma. Patients with schwannomatosis had lower numbers of non-vestibular cranial schwannomas, but more peripheral and spinal nerve schwannomas with pain as a predominant presenting symptom. Life expectancy was significantly better in schwannomatosis (mean age at death 76.9) compared with NF2 (mean age at death 66.2; p=0.004). CONCLUSIONS: Within the highly ascertained North-West England population, schwannomatosis has less than half the birth incidence and prevalence of NF2.

Hearing Rehabilitation in Neurofibromatosis Type 2.

Bilateral vestibular schwannomas are almost pathognomonic of neurofibromatosis type 2 (NF2). As a result of these tumors, hearing loss is the presenting symptom in 60% of adults and 30% of children with NF2. It is often bilateral. The best means of preserving hearing in patients with NF2 is conservative management. Even so at least 28% of patients have progression of hearing loss following diagnosis. The likelihood of progression of hearing loss is, at least in part, determined by the type of mutation. Treatment of vestibular schwannomas often has a detrimental effect on hearing. Only 41% of patients having stereotactic radiosurgery maintain their hearing at 5 years. Treatment with bevacizumab maintains medium-term hearing in 38% and improves it in 48%. Surgery to remove vestibular schwannomas invariably leads to complete loss of ipsilateral hearing, although in a very limited number of patients hearing preservation surgery may be possible. For those that lose their hearing but have an intact cochlear nerve, for example, conservative management, radiotherapy treatment or cochlear nerve preserving surgery, cochlear implantation has been shown to be an effective option although outcomes are not as good as traditional implant candidates (mean sentence testing scores in quiet: stable untreated tumors 69%; radiotherapy treated tumors 49%; cochlear nerve preserving surgery ∼40%). For those that do not have a functional cochlear nerve, auditory brainstem implantation (ABI) is an option. The non-user rate in this group is 13%. The mean sentence score in users with ABI alone is 12%. ABI therefore acts, in most cases, as an aid to lip reading and rarely provides open set speech discrimination.

Outcomes of cochlear implantation in patients with neurofibromatosis type 2.

In neurofibromatosis type 2 (NF2) bilateral vestibular schwannomas (VS) or their treatment usually results in bilateral hearing loss. Cochlear implantation (CI) was traditionally not used in these patients due to concern that retrocochlear disease would render the implant ineffective. This paper describes the auditory outcomes of CI in 13 patients with NF2 and includes patients with untreated VS and patients undergoing VS removal with cochlear nerve preservation. The non-user rate was 7.7%. Of the active users, median CUNY score was 98%, median BKB score in quiet was 90% and median BKB score in noise was 68%. CI is a viable option in selected patients with NF2.

Cochlear implantation in early deafened, late implanted adults: Do they benefit?

OBJECTIVES: The aim of this study was to quantify the benefit gained from cochlear implantation in pre- or peri-lingually deafened patients who were implanted as adults Methods: This was a retrospective case-control study. Auditory (BKB/CUNY/3AFC/Environmental sounds), quality of life (GBI/HUI3) and cognitive (customized questionnaire) outcomes in 26 late implanted pre- or peri-lingually deafened adults were compared to those of 30 matched post-lingually deafened, traditional cochlear implant users. RESULTS: There was a statistically significant improvement in all scores in the study group following cochlear implantation. BKB scores for cases was 49.8% compared to 83.6% for controls (p=0.037). CUNY scores for cases was 61.7% compared to 90.3% for controls (p=0.022). The 3AFC and environmental sounds scores were also better in controls compared to cases but the difference was not statistically significant. Quality of life scores improved following implantation in cases and controls but the improvement was only statistically significant in the controls. There was a 7.7% non-user rate in the cases. There were no non-users in the control group. DISCUSSION: Early deafened,,late implanted patients can benefit audiologically from cochlear implantation and in this study the improvement in speech discrimination scores was greater than expected perhaps reflecting careful selection of patients. Nevertheless, audiological benefits are limited compared to traditional cochlear implant recipients with the implant acting as an aid to lip reading in most cases. CONCLUSION: With careful selection of candidates, cochlear implantation is beneficial in early deafened, late implanted patients.

Straight versus modiolar hugging electrodes: does one perform better than the other?

OBJECTIVE: To determine differences in speech perception outcomes for patients who received a CI422 and a Contour cochlear implant. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Thirty-two adults who underwent cochlear implantation. INTERVENTION: Cochlear implantation using a CI422 or Contour device. MAIN OUTCOME MEASURE: Bamford-Kowal-Bench (BKB) speech perception scores at 3 and 9 months after activation. RESULTS: The mean BKB scores at 3 months for the CI422 device were 86.0% in quiet and 55.1% in noise. This compares with 86.0% in quiet and 62.3% in noise for the Contour device. At 9 months, the mean BKB scores were 85.9% in quiet and 67.1% in noise for the CI422 and 90.1% in quiet and 77.6% in noise for the Contour device. There was no statistically significant difference (p > 0.05) between speech perception outcomes at 3 or 9 months. CONCLUSION: This study suggests that CI422 and Contour electrode both improve speech perception outcomes postoperatively, and there does not appear to be any significant difference in outcome between the two types of devices.

Progress of hearing loss in neurofibromatosis type 2: implications for future management.

The objective of this study was to describe changes in hearing over time in patients with neurofibromatosis type 2 (NF2) treated conservatively. A retrospective case review was conducted in a tertiary referral centre. Pure tone audiometry, speech discrimination scores, serviceable hearing (American Academy of Otolaryngology class A or B) and measurement of vestibular schwannoma (VS) size on magnetic resonance imaging were evaluated in 56 patients (89 ears) with NF2 with at least one conservatively managed VS. Over a mean follow-up period of 7 years (range 0.8-21 years) pure tone average thresholds increased gradually with a mean annual rate of 1.3 dB for the right ear (p = 0.0003) and 2 dB for the left ear (p = 0.0009). Speech discrimination scores dropped with an average annual rate of 1.3 and 0.34% in the right and left ear, respectively. Patients maintained serviceable hearing for an average of 7.6 years (range 2.7-19.3 years). The average annual VS growth was 0.4 mm without any correlation with hearing loss. There was a correlation between patients' age and pure tone threshold increase (p < 0.05 for both ears). In this selected population of patients with NF2, hearing threshold increases were very slow. In NF2 patients with indolently behaving tumours, serviceable hearing can be maintained for a significant length of time, making conservative management an attractive option.

Surgical outcomes in cystic vestibular schwannoma versus solid vestibular schwannoma.

OBJECTIVE: To review the postoperative surgical outcomes of cystic vestibular schwannomas (CVSs), especially facial nerve outcomes, and compare these results with those from matched solid vestibular schwannomas (SVS) resected during the same period at a tertiary referral center. STUDY DESIGN: Retrospective case series. METHODS: One hundred thirty-one surgically managed patients with cystic vestibular schwannomas (CVSs) were age, sex, and tumor size matched to 131 surgically managed patients with solid vestibular schwannomas (SVSs). Demographics, tumor morphology, surgical approach, extent of resection, facial and nonfacial complications, and recurrence rates were compared between the 2 groups. Subtotal removal was defined as removal of at least 95% of the tumor. RESULTS: The mean maximal tumor diameter was 2.8 cm for both groups. For CVS, gross total tumor resection (GTR) was achieved in 92 patients (70.2%), and subtotal tumor resection (STR) was achieved in 39 patients (29.8%). Postoperative facial nerve outcomes at 1-year follow-up were good (HB Grade I-III) in 116 (88.5%) of 131 CVS patients. Twenty-three patients developed nonfacial nerve-related complications (17.6%). For SVS, GTR was achieved in 102 patients (77.9%), and STR was achieved in 29 patients (22.1%). Postoperative facial nerve outcomes at 1-year follow-up were good (HB Grade I-III) in 118 (90.1%) of 131 SVS patients. Nonfacial nerve related complications occurred in 14 patients (10.7%). None of the differences in outcome between the 2 groups were statistically significant. CONCLUSION: The difference in surgical outcomes is minimal between patients with CVS and those with SVS, not reaching statistical significance. We think, with judicious surgical management, similar outcomes can be achieved in cystic tumors and solid tumors.

Cochlear implantation in children with auditory neuropathy spectrum disorders.

AIM: To present the outcomes of cochlear implantation (CI) in children with auditory neuropathy spectrum disorders (ANSD). MATERIALS AND METHODS: The pre- and post-CI hearing outcomes in children with ANSD were retrospectively evaluated. Performance was assessed with categories of auditory performance (CAP) and the Manchester spoken language development scale (MSLDS). RESULTS: Full data were available in 27 implanted children with ANSD with average age at implantation 35.4 months (range 19-68 months). Nine children were implanted bilaterally, while 13 were bimodal. The pre-CI CAP and MSLDS scores were 2.5 (range 0-5) and 2.5 (range 0-6), while the post-CI scores 5.8 (range 2-9) and 7.7 (range 3-10), respectively. CONCLUSIONS: Although the outcome of CI in children with ANSD might vary, it is favourable in most of the cases. CI seems a justified hearing rehabilitation option for children with ANSD and limited benefits from conventional hearing aids.

Neurofibromatosis type 2 (NF2): diagnosis and management.

Neurofibromatosis type 2 (NF2) is an autosomal dominant inherited tumor predisposition syndrome caused by mutations in the NF2 gene on chromosome 22. Affected individuals develop schwannomas typically involving both vestibular nerves leading to hearing loss and eventual deafness. Rehabilitation with brainstem implants and in some cases cochlear implants is improving this outcome. Schwannomas also occur on other cranial nerves, on spinal nerve roots and peripheral nerves, and intracutaneously as plaques. Cranial and spinal meningiomas and spinal ependymomas are other common tumors. Fifty to sixty percent of patients represent de novo mutations and as many as 33% of these are mosaic for the underlying disease causing mutation. Truncating mutations (nonsense, frameshift insertions/deletions) are the most frequent germline events and cause the most severe disease, whilst single and multiple exon deletions are common and are usually associated with milder NF2. Neurological deficits are a major feature of the condition and neurologists have a pivotal role in assigning symptoms to lesions and in managing neuropathies. NF2 represents a difficult management problem with most patients facing substantial morbidity and reduced life expectancy. Surgery remains the focus of current management although watchful waiting and occasionally radiation treatment have a role. We are seeing the advent of tailored drug therapies aimed at the genetic level and these are likely to provide huge improvements for this devastating, life-limiting condition.

Growth characteristics of vestibular schwannomas.

OBJECTIVE: To assess the growth characteristics of small- to medium-sized vestibular schwannomas in patients undergoing watch, wait, and rescan management. STUDY DESIGN: Cohort study using prospectively collected size and tumor morphology data. SETTING: Tertiary referral center for cranial base surgery. SUBJECTS AND METHODS: Three hundred eighty-one patients with sporadic unilateral vestibular schwannomas and 2 or more magnetic resonance scans were included. Linear measurements were used to assess tumor size. The point of growth and pattern of growth progression were assessed. Factors influencing growth were investigated. RESULTS: Approximately 33% of tumors demonstrated significant growth. Mean size at presentation was 9.9 mm (standard deviation [SD]. 4.8). For growing tumors, mean size at final review was 13.7 mm (SD, 4.8). This was a statistically significant increase in size (p < 0.0001). Mean annual change in size for growing tumors was 2.3 mm (SD, 2.3). 52.4% of growing tumors showed radiologically demonstrable first growth within 18 months of presentation. Approximately 7.2% of tumors showed radiologically demonstrable first growth after 5 years of follow-up. There were no demographic or morphologic predictors of growth. CONCLUSION: Tumor growth is usually slow and is most likely to occur within the first 3 years of observation. Growth may occur after five years of follow-up. A protocol for the scanning of patients is suggested based on the findings of the study.