10.14639/0392-100X-N2322
Objective. To report surgical outcomes of a cohort of small sporadic vestibular schwannoma and discuss the role of early surgery. Methods. Retrospective descriptive analysis of 234 consecutive patients with small vestibular schwannoma operated on with translabyrinthine or hearing preservation surgical approaches. Outcome measures were control of disease, postoperative facial nerve function, complications and hearing outcome. Results. A translabyrinthine approach was performed in 59% of cases, hearing preservation surgery in 40% and transmeatal approach in 1%, respectively. Complete resection was achieved in 100% of cases. Overall, postoperative major and minor complications were 8.5% in the series, with complete recovery and no sequalae. Facial nerve function at one year postoperatively was House-Brackmann scale (HB) 1-2 in 95% of cases. The rate of hearing preservation was 70% A-B-C classes of Tokyo classification and 77% AB classes of AAOHNS classification. Conclusions. Early surgery in small vestibular schwannoma is a valid option, due to good functional outcomes, low morbidity and definitive cure. Early surgery is associated with better outcomes when considered in relation to non-surgical treatments reported in the literature.
text/xml
1827-675X
2322
en
Antonio Mazzoni
http://creativecommons.org/licenses/by-nc-nd/4.0
ACTA Otorhinolaryngologica Italica
hearing preservation surgery
Early surgery and definitive cure in small sporadic vestibular schwannoma
Text.Serial.Journal
https://www.actaitalica.it/
42
Skull base surgery
2022-11-23
2022-10-02
2022-12-13
2022-12-13
481-486
1
Antonio Mazzoni
2022/11/23
10.14639/0392-100X-N2322
481
Department of Neurosciences, Section of Otolaryngology, Azienda Ospedale-Università Padova, Padua, Italy
1827-675X
hearing preservation surgery
en
486
Early surgery and definitive cure in small sporadic vestibular schwannoma
https://www.actaitalica.it/article/download/2322/874
42
ACTA OTORHINOLARYNGOLOGICA ITALICA 2022;42:481-486; doi: 10.14639/0392-100X-N2322




Skull base surgery


Early surgery and definitive cure in small sporadic
vestibular schwannoma
Chirurgia precoce e guarigione definitiva nel piccolo schwannoma vestibolare
sporadico
Elisabetta Zanoletti1, Stefano Concheri1, Giulia Tealdo1, Diego Cazzador1, Luca Denaro2, Domenico d’Avella2,
Antonio Mazzoni1
1
  Department of Neurosciences, Section of Otolaryngology, Azienda Ospedale-Università Padova, Padua, Italy; 2 Department of
Neurosciences, Academic Neurosurgery, University of Padua, Padua, Italy


SUMMARY
Objective. To report surgical outcomes of a cohort of small sporadic vestibular schwan-
noma and discuss the role of early surgery.
Methods. Retrospective descriptive analysis of 234 consecutive patients with small ves-
tibular schwannoma operated on with translabyrinthine or hearing preservation surgical ap-
proaches. Outcome measures were control of disease, postoperative facial nerve function,
complications and hearing outcome.
Results. A translabyrinthine approach was performed in 59% of cases, hearing preserva-
tion surgery in 40% and transmeatal approach in 1%, respectively. Complete resection was
achieved in 100% of cases. Overall, postoperative major and minor complications were
8.5% in the series, with complete recovery and no sequalae. Facial nerve function at one
year postoperatively was House-Brackmann scale (HB) 1-2 in 95% of cases. The rate of
hearing preservation was 70% A-B-C classes of Tokyo classification and 77% AB classes
of AAOHNS classification.
Conclusions. Early surgery in small vestibular schwannoma is a valid option, due to good
functional outcomes, low morbidity and definitive cure. Early surgery is associated with
better outcomes when considered in relation to non-surgical treatments reported in the lit-
erature.
                                                                                                Received: October 4, 2022
KEY WORDS: vestibular schwannoma, definitive cure, early surgery, translabyrinthine             Accepted: October 8, 2022
surgery, hearing preservation surgery
                                                                                                Correspondence
RIASSUNTO                                                                                       Stefano Concheri
                                                                                                Department of Neurosciences, Section of Otolaryn-
Obiettivo. Presentare i risultati chirurgici di una serie di piccoli neurinomi sporadici e
                                                                                                gology, Azienda Ospedale-Università Padova, via
discutere il ruolo della chirurgia precoce nel trattamento.                                     Giustiniani 2, 35128 Padua, Italy
Metodi. Analisi retrospettiva e descrittiva di 234 pazienti affetti da piccolo schwannoma       E-mail: stefano.concheri_01@aopd.veneto.it
vestibolare operato con approccio translabirintico o chirurgia di preservazione dell’udito
(HPS). I risultati sono discussi alla luce del controllo di malattia, della funzione postope-
ratoria del nervo facciale, dell’insorgenza di complicanze e della preservazione uditiva.         How to cite this article: Zanoletti E, Concheri S,
Risultati. L’approccio translabirintico è stato eseguito nel 59% dei casi, HPS nel 40% e          Tealdo G, et al. Early surgery and definitive cure
                                                                                                  in small sporadic vestibular schwannoma. Acta
quello transmeatale nell’1%. La resezione completa è stata ottenuta nel 100% dei casi.
                                                                                                  Otorhinolaryngol Ital 2022;42:481-486. https://
Si sono osservate complicanze postoperatorie nell’8,5% dei casi, risoltesi con completa           doi.org/10.14639/0392-100X-N2322
guarigione e assenza di sequele. La funzione del nervo facciale a 1 anno dall’intervento è
stata I-II HB nel 95% dei casi; il tasso di conservazione dell’udito del 70% in classe A-B-     © Società Italiana di Otorinolaringoiatria
C secondo la classificazione di Tokyo e del 77% in classe A-B secondo la classificazione        e Chirurgia Cervico-Facciale
AAO-HNS.
Conclusioni. La chirurgia precoce nel piccolo schwannoma vestibolare si è rivelata essere                      OPEN ACCESS
un’opzione conveniente in alternativa alle terapie non chirurgiche, considerate nell’intero
                                                                                                This is an open access article distributed in accordance with
corso della terapia, in ragione dei risultati, della bassa morbidità e della guarigione de-     the CC-BY-NC-ND (Creative Commons Attribution-Non-
finitiva.                                                                                       Commercial-NoDerivatives 4.0 International) license. The
                                                                                                article can be used by giving appropriate credit and mentio-
PAROLE CHIAVE: piccolo schwannoma vestibolare, chirurgia precoce, chirurgia                     ning the license, but only for non-commercial purposes and
translabirintica, chirurgia di preservazione dell’udito, guarigione definitiva                  only in the original version. For further information: https://
                                                                                                creativecommons.org/licenses/by-nc-nd/4.0/deed.en




                                                                                                                                                        481
E. Zanoletti et al.




Introduction                                                      tion of the procedure for hearing preservation purposes 16,17.
                                                                  Intraoperative continuous facial nerve electromyography
Small vestibular schwannoma (VS) is defined as a tumour
                                                                  (EMG) monitoring was adopted with NIM-Response 3.0,
of less than or equal to 10 mm in size in the cerebello-pon-
                                                                  Medtronic Xomed Inc. Intraoperative hearing was moni-
tine angle (CPA) and to a various extent in the internal audi-
                                                                  tored with NIM-Eclipse, Axom Medtronic Inc.
tory canal (IAC) 1,2. Use of high-resolution magnetic reso-
nance imaging (MRI) in the diagnosis of unilateral hearing
                                                                  Outcomes
loss or vestibular dysfunction has allowed small vestibular
                                                                  Completeness of tumour resection, peri- and postoperative
schwannoma to be diagnosed with higher frequency than
                                                                  complications, facial nerve and hearing function were the
in the past. The current challenge is to promote a treatment
                                                                  main outcomes. Tumour resection was assessed intraop-
where early diagnosis allows no further functional losses,
                                                                  eratively and at 1, 3, 6, and 10 years postoperatively with
definitive cure, and least impact on the healthcare system.
                                                                  contrast-enhanced MRI. We defined as postoperative ma-
Observation, surgery, and radiotherapy are the therapeu-
                                                                  jor complications brain or cerebellar edema/infarction, hy-
tic options, but their indications are a matter of ongoing
                                                                  drocephalus, intracranial hypertension, symptomatic dural
debate 3-7. The short and mid-term outcomes favour both
                                                                  venous sinuses thrombosis, 5th, 6th, 9th-11th cranial nerve
observation and radiotherapy, but it gradually emerged that
the outcome must include both the long-term 8,9 and the full      impairment, meningitis, nasal cerebrospinal fluid (CSF)
course of therapy, including surgery, in failures 10-12. As ad-   leakage requiring revision surgery and extradural haemato-
ditional data on non-surgical therapies is being made avail-      ma requiring evacuation. Minor complications were wound
able, a change in the current trends is emerging 13-15.           CSF leakage and nasal CSF leakage treated conservatively,
The aim of this study was to present a consecutive series of      and haematoma in the abdominal site of fat harvesting.
patients treated for small VS with a translabyrinthine (TLAB)     Facial nerve outcome was evaluated at discharge and 12
approach or hearing preservation surgery (HPS). We also aim       months after surgery. It was graded from I to VI according
to offer a contribution to the debate on therapy in small ves-    to the House-Brackmann (HB) scale 18. HB Grades I and II
tibular schwannoma and combine our and the literature data to     corresponded to good facial nerve function.
reappraise the role of surgery in small tumours.                  In the group of patients submitted to HPS, preoperative
                                                                  hearing of “in-protocol” cases designated ≤ 30 db PTA,
                                                                  ≥ 70 SDS and normal or slightly altered auditory brainstem
Materials and methods                                             responses (ABR).
Population                                                        Hearing was measured with pure tone average (PTA)
Data on 234 consecutive patients diagnosed with small             at 0.5, 1, 2 and 4 KHz, and speech discrimination score
(i.e., intrameatal tumours or lesions with ≤10 mm extension       (SDS). Hearing was classified according to the American
in the CPA) VS and treated surgically were retrieved from a       Academy Otolaryngology-Head and Neck Surgery (AAO-
prospectively maintained database and retrospectively ana-        HNS) 19 and the Tokyo B 2 classifications. According to the
lysed for this study. Clinical, surgical, and radiological data   Tokyo classification, in classes C, D, E, F “a better speech
were obtained.                                                    discrimination score class than the PTA class made the cat-
Patients were all operated on by the same team (A.M., E.Z.,       egory of the patient one class better”. This means that a
D.d’A., L.D.) between 1973 and 2021. Tumour size was the          31-40 PTA with > 70% SDS upgrades class C to B, a 41-60
inclusion criterion: only small VS were included. Tumour size     PTA with > 60% SDS upgrades class D to C.
was preoperatively measured as the largest diameter (mm) in
the CPA on contrast enhanced T1 sequences for extrameatal
                                                                  Results
lesions, and as the maximal tumour length for intrameatal
ones 2. For diagnoses between 1980 and 1990, tumour meas-         Two hundred and thirty-four patients met the inclusion cri-
ures were performed using contrast-enhanced CT.                   teria and were enrolled in the study. The mean age at sur-
Patients with neurofibromatosis type 2, intralabyrinthine         gery was 52.4 years (range 10-77), and 50.8% were female.
VS, previously irradiated VS, and CPA/intrameatal lesions         Sixty-one cases (26.0%) were diagnosed with intrameatal
other than VS were excluded.                                      VS and 173 (74.0%) with extrameatal tumours (mean tu-
                                                                  mour size in the CPA 6.9 mm, range 1-10 mm). Tumour
Surgical procedure                                                characteristics are presented in Table I. A TLAB approach
All the selected patients were surgically treated with TLAB,      was the procedure used in 138 cases (59.0%), HPS in 94
or transmeatal, or retrosigmoid approaches. The latter en-        (40.0%) and transmeatal in 2 (1.0%). Cochlear implanta-
compassed the retrolabyrinthine meatotomy, a modifica-            tion was performed in 11 cases (4.8%), 10 in TLAB ap-



482
                                                                                                                      Early surgery in small vestibular schwannoma




Table I. Tumour characteristics.                                                          I-II HB facial nerve function did not show a significant dif-
                              N (%)                     Tumour size (mm)                  ference between the surgical procedures (translabyrinthine
 Intrameatal tumours             61 (26)                   Mean (7.63)                    vs HPS, p = 0.118) and the subsites of tumour extension
                                                            Median (8)                    (purely intrameatal vs intra-extrameatal, p = 0.233).
                                                           Range (3-13)                   As for hearing outcomes, in the HPS “in protocol” cohort,
 Extrameatal tumours             173 (74)                   Mean (6.9)                    postoperative class A of AAO-HNS and class AB of To-
                                                            Median (8)
                                                           Range (1-10)                   kyo designating “good” hearing were, respectively, 30.0%
 Total                          234 (100)
                                                                                          (20/65) and 49.0% (32/65). Class AB of AAO-HNS desig-
                                                                                          nating both “good” and “serviceable” hearing was 76.0%
                                                                                          (42/62), class AB of Tokyo, inclusive of B upgraded to C
proach (simultaneous in 5 and sequential in 4), and one in                                (with PTA between 30 and 40 dB and > 70% SDS), des-
HPS failure. Radiological and clinical follow-up was avail-                               ignating both “good” and “socially useful” hearing, was
able for all patients. Two patients, one HPS and one TLAB,                                71.0% (44/62).
had less than 1 year follow-up and were excluded by clini-
cal evaluation of facial nerve/hearing outcomes.                                          Discussion
Complete gross tumour resection was achieved in 100% of
                                                                                          Over 50 years of microsurgery as well the long experience
cases, but three recurrences were observed over the years in
                                                                                          with radiotherapy and observation are expected to offer
patients with HPS (overall 1.3%; 3% of HPS subgroup of pa-
                                                                                          sufficient data to indicate the most appropriate treatment
tients); two were operated on with a revision HPS with hear-
                                                                                          for small vestibular schwannoma 4,6,7. The surgical outcome
ing preserved in one case, and one with a TLAB approach.
                                                                                          has been known for decades 20 and recently improved to the
Overall, 8.5% of cases (20 patients) experienced major                                    present levels 14,15. The outcome of observation and radio-
(5.1%, 12 cases) and minor (3.4%, 8 cases) postoperative                                  therapy took more time to assess mid- to long-term growth
complications. No events such as death, intracranial hae-                                 as it was to include the result of the full course of therapy,
matoma, or meningitis were observed. Major complica-                                      that is of secondary surgery in failures due to growth of the
tions are reported in detail in Table II. Minor complications                             observed or radiated tumour 10-12. This changed the balance
(8 cases, 3.4% in all the series) were transient retroauricu-                             between the three options, i.e. observation, radiotherapy
lar wound swelling and abdominal haematoma at the site                                    and microsurgery, as follows.
of fat-graft harvesting in the TLAB procedures. All patients                              1) Observation has been a widely used first-line treatment
with major and minor complications recovered completely                                   in small-medium size tumours 9,21 and was based on the
and no sequalae were observed.                                                            assumption that most small tumours do not grow 21. This
Facial nerve function at 12-months postoperatively was:                                   supported the choice of wait and see protocols in small
grades I-II HB in 95.0% of cases (220/232), grade III in                                  tumours, although the unpredictability of growth required
3.9% (9/232) and grade V and VI in 0.9% (2/232) and 0.4%                                  continual control. A more accurate volumetric measurement
(1/232) of cases respectively. The cases with ≥ III° HB facial                            of tumour size showed a 65% growth rate 22 and changed
nerve included those with intraoperative loss of continuity                               our view on the natural history of small vestibular schwan-
and immediate reconstruction with graft (2%, 5 cases).                                    noma. Moreover, the results of surgery on small tumours
Details on facial nerve outcomes are shown in Table III.                                  are superior to those of medium-large tumours 5,14,15,20. An

Table II. Major complications.
 Description                                                     N (%*)      Surgical procedure              Treatment                       Outcome
                                                                                    (%‡)
 Transient cerebellar oedema with hydrocephalus and              1 (0.4)           1 HPS (1)         Transient external ventricular      Complete recovery
 partial sigmoid sinus thrombosis                                                                                drain
 Nasal CSF leakage                                                7 (3)            5 HPS (5)               Surgical revision             Complete recovery
                                                                                  2 TLAB (1.4)      or/and transient lumbar drain
 Wound CSF leakage                                               1 (0.4)            HPS (1)         Surgical revision and transient      Complete recovery
                                                                                                             lumbar drain
 Late transient temporal oedema                                  1 (0.4)           1 HPS (1)              Medical treatment              Complete recovery
 Wound extradural haematoma                                      2 (1.5)           2 HPS (2)                Surgical drain               Complete recovery
CSF cerebrospinal fluid; HPS hearing preservation surgery; TLAB translabirintine.
*
  % of all procedures (N = 234). ‡% of the considered procedures: HPS (N = 94) or TLAB (N = 138).




                                                                                                                                                             483
E. Zanoletti et al.




Table III. Postoperative facial nerve function; cases that required intraoperative reconstruction (n = 5, 2%) are included.
 Facial nerve grading                           All cases                 TLAB/                     HPS                Extrameatal   Intrameatal
 (H-B)                                            N (%)               Trans meatal                 N (%)                 tumours       tumours
                                                                          N (%)                                            N (%)         N (%)
 I                                                  197 (84.91)      110 (79.14)              87 (93.55)             140 (81.40)     57 (95.00)
 II                                                  23 (9.91)       19 (13.67)                4 (4.30)              21 (12.21)       2 (3.33)
 III                                                  9 (3.88)         7 (5.04)                2 (2.15)                8 (4.65)       1 (1.67)
 IV                                                     0 (0)            0 (0)                   0 (0)                   0 (0)          0 (0)
 V                                                    2 (0.86)         2 (1.44)                  0 (0)                 2 (1.16)         0 (0)
 VI                                                   1 (0.43)         1 (0.72)                  0 (0)                 1 (0.58)         0 (0)
 Total                                               232 (100)        139 (100)                93 (100)               172 (100)       60 (100)
TLAB: translabyrintine; HPS: hearing preservation surgery.


argument against the observational strategy is that growth                         has hardly been investigated. Comparing surgery and RT
during observation leads to surgery on a larger tumour and                         with the currently available data shows that both therapies
worse facial nerve outcomes 13. Facial nerve outcomes were                         have suboptimal results with small differences in rates. The
compared based on initial treatment strategy, so that pa-                          key point is that data on facial nerve preservation and other
tients operated on at diagnosis with primary surgery were                          complications after primary radiotherapy do not include the
compared with patients allocated to conservative manage-                           outcome of secondary surgery in failures. Poor outcomes
ment and operated on after established tumour growth. The                          both on facial nerve function (66% of facial nerve impair-
conclusion was that surgical treatment was to be adminis-                          ment) and incomplete resection 11 have been reported. Pres-
tered as soon as growth was established irrespective of tu-                        ervation of facial nerve is considered a burden of salvage
mour size. This radically changed the authors’ previous in-                        surgery in irradiated patients 10-12, whereas the importance
dication to wait and see protocols. The recent literature 14,15                    of definitive cure of the disease to our knowledge has never
points to the fact that 1 cm in the CPA is the critical size                       been discussed in literature. Tumour control was the term
allowing good preservation of the facial nerve. Allocat-                           used for non-surgical treatments.
ing a 1 cm tumour to observation involves a higher risk                            3) Microsurgery, in our experience, allowed preservation of
of impaired facial function in the case of delayed surgery.                        I-II HB facial nerve function in 95% of cases, and HB > 3
The benefits of early surgery on small (< 1 cm) vs medium-                         in 5% including cases with nerve graft due to intraoperative
sized tumours (between 1 and 2 cm) was also evident in our                         loss of continuity (Tab. III). These results support the role
experience15 when facial nerve outcomes were compared                              of primary surgery in small growing tumors, as recently
between the two groups wherein surgery on small tumours                            reported in the literature 14,15. If such results are compared
offered excellent rates of functional preservation. Our con-                       with the facial nerve outcomes after failed observation or
clusion was that early surgery on a small, growing tumour                          radiotherapy, in which the poor facial nerve outcome after
was a viable alternative to observation.                                           salvage surgery adds up to the loss due to the primary treat-
2) Radiotherapy (RT) is an active treatment alternative to                         ment, early proactive surgery 14,15 appears to be a preferable
surgery. The use of RT irrespective of tumour growth, with                         alternative to the non-surgical therapies.
the goal of preventing growth in a potentially non-growing                         TLAB and retrosigmoid approach with retrolabyrinthine
tumour, was the commonest therapy until the recent, in-                            meatotomy were the microsurgical procedures, apart from
frequent switch to radiate the tumour after growth is ob-                          the few transmeatal approaches. Indications for TL or HPS
served 23. Lerner 12 reported on the outcomes of primary                           were based on hearing, age/surgical risk and the patient’s
radiotherapy on the facial and other cranial nerves in small-                      desire. The cases with at least 30 PTA and 70% word rec-
medium size tumours; the 5.3% rate of short-term facial                            ognition score (WRS), with normal or slightly abnormal
paresis evolved to persistent facial impairment in 4% of                           ABR, were submitted to HPS 16. Cases with poorer hearing
cases. Intrameatal tumours with extension to the fundus ap-                        were observed and after assessing growth were submitted to
peared to be at higher risk for post-treatment facial paresis,                     TLAB surgery, but two cases to the transmeatal approach.
as the most fragile labyrinthine tract was exposed to radia-                       As for surgical complications, the TL group presented an
tion, not differently from the cochlea. The effects of tempo-                      uneventful postoperative course with quick recovery in all
rary tumour enlargement after radiotherapy in intrameatal                          but one case (0.7% of TLAB cases and 0.4% of the en-
tumours were also reported 24 but the issue on radiation                           tire series), where a vasogenic temporal oedema occurred,
outcomes other than growth in a small, growing tumour                              evolving to complete recovery. In the HPS group, two ex-



484
                                                                                            Early surgery in small vestibular schwannoma




tradural haematomas (2.1% of the HPS) were treated with            The strong point seems to be that the role of definitive cure
surgical evacuation, and one case of transient hydrocephalus       of the disease, which has so far been disregarded when bal-
for cerebellar oedema was successfully treated with tempo-         ancing conservative therapies like observation and radio-
rary ventricular drain. Recurrence from residual tumour in         therapy vs surgery, can only be assigned to surgery.
HPS treated with revision surgery occurred in the first 50
cases, and it did not with the last meatotomy technique that       Conclusions
provided control of the distal extent of the tumour 17. No case
in the series presented permanent sequalae after these ma-         Small vestibular schwannoma is a completely different dis-
jor complications. To our knowledge, the reported rates of         ease from a larger size tumour, and being the most diag-
permanent complications in a small-medium sized tumour             nosed it requires effort to determine the best management.
after primary radiotherapy involved hydrocephalus requiring        This goal is possible due to the several years of experience
ventriculo-peritoneal drain in 4-6% of cases and permanent         with the three current therapies: observation, surgery and ra-
multiple cranial nerves dysfunction (cochlear, facial, trigem-     diotherapy. While surgery can obtain a definitive outcome
inal, lower cranial nerves) in 24.5% of cases, in 2% of cases      in one year, morbidities and success/failure, observation and
permanent > 3 HB facial nerve loss of function 12. If the men-     radiotherapy need a longer duration of follow-up. A non-sur-
tioned upfront postsurgical complications are compared with        gical therapy can be soundly evaluated, if the result includes
the complications of first-line radiotherapy and especially        the full course of therapy in terms of long-term outcomes
of secondary surgery 10-12, the balance appears to point to a      and the effects of secondary therapy on failures, in particular
more favourable outcome of primary surgery. In the group           salvage surgery. The worse facial nerve results after delayed
of HPS patients, serviceable hearing preservation was suc-         surgery in failed observation or secondary surgery in failed
cessful in 71% and 76% of the “in-protocol” cases, accord-         radiotherapy represents the price that non-surgical therapies
ing to the two classification systems 2,19. The rate decreased     pay in small VS. Surgery appears to be superior in terms of
to 23% in the “off-protocol cases” in both classifications.        definitive cure with quick recovery to normal life and no or
This is likely to support the principle that HPS is expected       minimal further losses or complications. The decisive aspect
to provide better long-term hearing results than conservative      of outcome in favour of surgery is that in growing tumours
therapies, such as 23% of preserved A-B AAOHNS class at            non-surgical therapies fail, requiring secondary surgery with
10 years in observation 9, and 34% in radiotherapy 8. Within       poorer results than in an early-treated smaller tumour. The
this perspective, HPS seems to comply with the statement           10 mm critical size is conventionally set for a small tumour,
“the only reason for active treatment (surgery or radiother-       which hardly contacts the brain stem and allows the least
apy) is attempted hearing preservation” 9 and seems to be a        surgical trauma. The two surgical therapies, TLAB and HPS
realistic goal. In the other cases of small tumours, when HPS      are different considering aim, execution, and burden on the
is deemed to have an unsuccessful outcome, observation re-         patient. TLAB surgery disregards hearing unfit for preser-
mains the choice and, if growth is assessed, a prompt shift to     vation and affords a definitive cure with the lowest rates of
TL surgery is recommended. Cochlear implant (CI) rehabili-         complications and no sequelae.
tation is considered in the case of preserved cochlear nerve 25    When hearing is the goal, HPS is an option requiring both
in early TL and failed HPS cases, whereas hearing aid re-          the patient’s and surgeon’s choice. Both TLAB and HPS
habilitation can be an option in preserved-hearing cases. In       for small tumours appear to be close to achieving the goals
clinical practice, when should surgery be performed for a          of definitive cure of the disease and functional preservation
small tumour? If hearing is the goal, growth is disregarded        or rehabilitation.
and HPS is advised at the shortest time after diagnosis with
the already mentioned hearing parameters. When hearing             Acknowledgements
is not preservable and growth is assessed, translabyrinthine       We thank Mrs. Alison Garside for the revision of the Eng-
surgery is advised when tumour gets close to 8-9 mm in size.       lish language.
The main weakness of the paradigm 10 mm size-obser-
vation-early surgery lies in the retrospective nature of this      Conflict of interest statement
study. The prospective, non-randomised study under way             The authors declare no conflict of interest.
cannot change this limitation. Other weak points are that sur-
gery itself is an invasive therapy, the questionable issues 7 of   Funding
observing a first diagnosis 10 mm tumour which has already         This research did not receive any specific grant from fund-
reached the threshold size for surgery, and the case of spon-      ing agencies in the public, commercial, or not-for-profit
taneous stop of growth beyond the 10 mm limit.                     sectors.



                                                                                                                                   485
E. Zanoletti et al.




Author contributions                                                               vestibular schwannoma. Neurosurgery 2017;80:49-56. https://doi.
                                                                                   org/10.1227/neu.0000000000001414
EZ: surgery; conceptualization; methodology; investiga-
                                                                              10
                                                                                   Husseini ST, Piccirillo E, Taibah A, et al. Salvage surgery of vestibu-
tion; data curation; original draft; writing-review and ed-                        lar schwannoma after failed radiotherapy: the Gruppo Otologico ex-
iting; supervision. SC: methodology; investigation; data                           perience and review of the literature. Am J Otolaryngol 2013;34:107-
curation; original draft; writing-review and editing. GT:                          114. https://doi.org/10.1016/j.amjoto.2012.09.012
surgery; methodology; original draft; writing-review and                      11
                                                                                   Lee HJ, Kim MJ, Koh SH, et al. Comparing outcomes following sal-
editing; supervision. DC: surgery; conceptualisation; meth-                        vage microsurgery in vestibular schwannoma patients failing gamma-
                                                                                   knife radiosurgery or microsurgery. Otol Neurotol 2017;38:1339-144.
odology; data curation; writing-review and editing; super-                         https://doi.org/10.1097/MAO.0000000000001536
vision. LD: surgery; conceptualization; supervision. Dd’A:                    12
                                                                                   Lerner DK, Lee D, Naples JG, et al. Factors associated with facial nerve
surgery; conceptualization; supervision. AM: surgery; con-                         paresis following gamma knife for vestibular schwannoma. Otol Neuro-
ceptualization; methodology; writing - review and editing;                         tol 2020;41:e83-e88. https://doi.org/10.1097/mao.0000000000002401
supervision.
                                                                              13
                                                                                   Kaltoft M, Stangerup SE, Caye-Thomasen P. Facial nerve function af-
                                                                                   ter vestibular schwannoma surgery following failed conservative man-
                                                                                   agement. Neurosurgery 2012;70:278-282. https://doi.org/10.1227/
Ethical consideration                                                              neu.0b013e31822f7d5f
The study was conducted in accordance with the principles                     14
                                                                                   Schwartz MS, Lekovic GP, Miller ME, et al. Translabyrinthine mi-
of the Helsinki Declaration and the data were collected,                           crosurgical resection of small vestibular schwannomas. J Neurosurg
                                                                                   2018;129:128-136. https://doi.org/10.3171/2017.2.JNS162287
grouped, and examined in agreement with Italian privacy                       15
                                                                                   Zanoletti E, Mazzoni A, Chiumenti FA, et al. Early translabyrinthine
and data laws. Before undergoing surgery, 220/234 patients                         surgery for small- and medium-sized vestibular schwannomas: con-
included in the study signed an informed consent. The re-                          secutive cohort analysis of outcomes. Otol Neurotol 2022;43:962-
maining 14 patients agreed retrospectively agreed for per-                         967. https://doi.org/10.1097/mao.0000000000003608
sonal data to be treated anonymously, in accordance with                      16
                                                                                   Mazzoni A, Zanoletti E, Denaro L, et al. Retrolabyrinthine meatot-
                                                                                   omy as part of retrosigmoid approach to expose the whole internal
the in-house rules for retrospective studies of the Otolaryn-                      auditory canal: rationale, technique, and outcome in hearing preser-
gology Section at Padova University (Italy).                                       vation surgery for vestibular schwannoma. Oper Neurosurg (Hagers-
                                                                                   town) 2018;14:36-444. https://doi.org/10.1093/ons/opx091
                                                                              17
                                                                                   Franz L, Mazzoni A, Martini A, et al. Position of retrosigmoid cra-
References                                                                         niotomy in hearing preservation surgery for vestibular schwan-
1
    Koos WT, Day JD, Matula C, et al. Neurotopographic considerations              noma. Oper Neurosurg 2022;22:179-186. https://doi.org/10.1227/
    in the microsurgical treatment of small acoustic neurinomas. J Neu-            ons.0000000000000083
    rosurg 1998;88:506-512. https://doi.org/ 10.3171/jns.1998.88.3.0506       18
                                                                                   House JW, Brackmann DE. Facial nerve grading system. Otolaryngol. Head
2
    Kanzaki J, Tos M, Sanna M, et al. New and modified reporting sys-              Neck Surg 1985;93:146-147. https://doi.org/10.1177/019459988509300202
    tems from the consensus meeting on systems for reporting results in       19
                                                                                   Committee on Hearing and Equilibrium guidelines for the evaluation
    vestibular schwannoma. Otol Neurotol 2003;24:642-648. https://doi.             of hearing preservation in acoustic neuroma (vestibular schwanno-
    org/10.1097/00129492-200307000-00019                                           ma). American Academy of Otolaryngology-Head and Neck Surgery
3
    Carlson ML, Habermann EB, Wagie AE, et al. The changing landscape              Foundation, INC. Otolaryngol Head Neck Surg 1995;113:179-80.
    of vestibular schwannoma management in the United States. A shift              https://doi.org/10.1016/S0194-5998(95)70101-X
    toward conservatism. Otolaryngol Head Neck Surg 2015;153:440-             20
                                                                                   Brackmann DE, Cullen RD, Fisher LM. Facial nerve function af-
    446. https://doi.org/10.1177/0194599815590105                                  ter translabyrinthine vestibular schwannoma surgery. Otolaryn-
4
    Anaizi AN, DiNapoli VV, Pensak M, et al. Small vestibular schwanno-            gol Head Neck Surg 2007;136:773-777. https://doi.org/10.1016/j.
    mas: Does surgery remain a viable treatment option? J Neurol Surg B            otohns.2006.10.009
    Skull Base 2016;77:212-218. https://doi.org/10.1055/s-0035-1564591        21
                                                                                   Stangerup SE, Caye-Thomasen P. Epidemiology and natural history
5
    Prasad SC, Patnaik U, Grinblat G, et al. Decision making in the wait-          of vestibular schwannomas. Otolaryngol Clin N Am 2012;25:257-
    and-scan approach for vestibular schwannomas: is there a price to pay          268. https://doi.org/10.1016/j.otc.2011.12.008
    in terms of hearing, facial nerve, and overall outcomes? Neurosurgery     22
                                                                                   Lees KA, Tombers NM, Link MJ, et al. Natural history of sporadic vestibu-
    2018;83:858-870. https://doi.org/10.1093/neuros/nyx568                         lar schwannoma: a volumetric study of tumor growth. Otolaryngol Head
6
    Chiluwal AK, Rothman A, Svrakic M, et al. Surgical outcome in                  Neck Surg 2018;159:535-542. https://doi.org/10.1177/0194599818770413
    smaller symptomatic vestibular schwannomas. Is there a role for           23
                                                                                   Marston AP, Jacob JT, Carlson ML, et al. Pretreatment growth rate
    surgery? Acta Neurochir (Wien) 2018;160:2263-2275. https://doi.                as a predictor of tumor control following Gamma Knife radiosurgery
    org/10.1007/s00701-018-3674-x                                                  for sporadic vestibular schwannoma. J Neurosurg 2017;127:380-387.
7
    Zanoletti E, Mazzoni A, Martini A, et al. Surgery of the lateral skull         https://doi.org/10.3171/2016.5.jns153013
    base: a 50-year endeavour. Acta Otorhinolaryngol Ital 2019;39:S1-         24
                                                                                   Kim YH, Kim DG, Han JH, et al. Hearing outcomes after stereotactic
    S146. https://doi.org/10.14639/0392-100X-suppl.1-39-2019                       radiosurgery for unilateral intracanalicular vestibular schwannomas:
8
    Carlson ML, Jacob JT, Pollock BE, et al. Long-term hearing outcomes            implication of transient volume expansion. Int J Radiat Oncol Biol
    following stereotactic radiosurgery for vestibular schwannoma: patterns        Phys 2013;85:61-67. https://doi.org/10.1016/j.ijrobp.2012.03.036
    of hearing loss and variables influencing audiometric decline. J Neuro-   25
                                                                                   Sorrentino F, Tealdo G, Cazzador D, et al. Cochlear implant in ves-
    surg 2013;118:579-587. https://doi.org/10.3171/2012.9.JNS12919                 tibular schwannomas: long-term outcomes and critical analysis of
9
    Kirchmann M, Karnov K, Hansen S, et al. Ten-year follow-up on tu-              indications. Eur Arch Otorhinolaryngol 2022;279:4709-4718. https://
    mor growth and hearing in patients observed with an intracanalicular           doi.org/10.1007/s00405-021-07243-0




486
