surgical removal of giant acoustic neuromas
TRANSCRIPT
PEER-REVIEW REPORTS
Surgical Removal of Giant Acoustic Neuromas
Joana Silva1, António Cerejo1, Filipe Duarte1, Fernando Silveira2, Rui Vaz1M
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INTRODUCTION
Radical surgical removal of giant acousticneuromas is a challenging task. Dysfunc-tion of facial nerve and hearing loss canoccur after surgery, and mortality and se-rious morbidity are possible when tumorsreach huge dimensions (7, 16). Currently,surgery is the main option in the manage-ment of giant acoustic neuromas. Al-though alternatives to radical surgery canbe considered (as staged resection or par-tial removal followed by radiosurgery [4,6, 11]), complete removal of the tumor in asingle operation is possible and is thetreatment of choice (14).
The outcome in a series of 29 patientswith giant acoustic neuromas (�40 mmin maximum diameter) submitted to rad-ical resection in a single operation wasretrospectively analyzed, namely, thepostoperative results concerning facialfunction and hearing. Surgical morbidityand evolution after surgery of preopera-tive neurologic conditions, like hydro-cephalus or facial hypoesthesia, were also
Key words� Facial nerve preservation� Giant vestibular schwannoma� Hearing preservation� Radical surgery
Abbreviations and AcronymsCSF: Cerebrospinal fluidHB: House-Brackmann grading systemMRI: Magnetic resonance imaging
From the Departments of 1Neurosurgery and2Neurophysiology, Hospital São João, University of
Porto, Porto, Portugal
To whom correspondence should be addressed:Joana Silva, M.D. [E-mail: [email protected]]
Citation: World Neurosurg. (2012) 77, 5/6:731-735.DOI: 10.1016/j.wneu.2011.08.019
Journal homepage: www.WORLDNEUROSURGERY.org
Available online: www.sciencedirect.com
1878-8750/$ - see front matter © 2012 Elsevier Inc.All rights reserved.
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WORLD NEUROSURGERY 77 [5/6]: 731-7
ATERIAL AND METHODS
atient Populationwenty-nine patients with giant acoustic neu-
oma consecutively operated in our Departmentetween 2005 and 2010 were included in thetudy. The mean age was 45 years (14-72 years),nd there were 12 female and 17 male patients.
linical Presentationome degree of hypoacousia was present in allases, without any cases of normal hearing (Ta-le 1). Tinnitus was referred in all cases. Threeatients had facial dysesthesia and there were
� OBJECTIVE: The authors present thgiant acoustic neuromas.
� METHODS: Twenty-nine patientsiameter greater than 40 mm, submitte010, were reviewed by a retrospectivurgical morbidity, facial nerve functioreoperative neurologic conditions w
RESULTS: All tumors were completwithout perioperative mortality. As compthree cases of local cerebrospinal fluidleak, two cases of meningitis, one pselower cranial nerve dysfunction. The apreserved in 86% and facial function inhypoglossal–facial anastomosis (72%), fain 13 cases (45%), fair (HB III) in 5 caseBefore surgery, 12 patients (41%) had uthese 12 patients (58%), it was possiblmoderate hearing), after surgical removaradiologic signs of hydrocephalus, twpatients presented with trigeminal neusensory loss and one with swallowing
� CONCLUSIONS: Total removal of laretrosigmoid approach with acceptablneurologic symptoms recovered afterpreservation was possible in the majorpreservation should be attempted if the
wo cases of trigeminal neuralgia (one on the p
35, MAY/JUNE 2012 ww
ontralateral side). In one case, there was diplo-ia due to sixth-nerve palsy. Ataxia was present
n eight cases, and nystagmus in two cases. Oneatient had a history of swallowing distur-ances.Signsofintracranialhypertensionledtoiagnosis in three patients, and, in two cases,
here was loss of vision associated with hydro-ephalus.
euroradiologic Findingsumor size ranged from 40 to 61 mm, in maxi-um diameter. Five of the tumors were cystic
Figure 1), and 24 were solid (Figure 2). Radio-ogic signs of hydrocephalus were present in six
tcome of radical surgical removal of
acoustic neuroma with maximumsurgery between the years 2005 and
udy. The extension of tumor removal,earing, and evolution after surgery ofhe studied parameters.
removed by a retrosigmoid approach,tions related to the surgery, there were, one case of nasal cerebrospinal fluideningocele, and one case of transientmic integrity of the facial nerve was. In the 21 patients who did not need
function was excellent or good (HB I-II)%), and poor (HB IV) in 3 cases (10%).
l (H2) or moderate (H3) hearing. In 7 ofpreserve some hearing function (withthe tumors. Six patients presented withthem with visual disturbances. Two
a (one contralateral), three with faciallems, that disappeared after surgery.
coustic neuroma can be achieved byrbidity and no mortality. Preoperativegery in most cases. Facial functionf cases. Even in large tumors, hearingent has useful hearing preoperatively.
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PEER-REVIEW REPORTS
JOANA SILVA ET AL. SURGICAL REMOVAL OF GIANT ACOUSTIC NEUROMAS
SurgeryAll cases were operated by the same surgeon(A.C.), using the retrosigmoid approach in asemi-sitting position, with intraoperativemonitoring (electromyography of facial nerveand auditory evoked potentials). All the pa-tients were admitted in the Neurocritical CareUnit immediately after surgery. A routine CTscan was done in all cases 6 to 8 hours after
Figure 1. Giant cystic acoustic neuroma: (A) preo
Table 1. Clinical Symptoms and Signsat Presentation
Hypoacousia 29 (100%)
Tinnitus 29 (100%)
Facial dysesthesia 3 (10%)
Trigeminal neuralgia 2*(7%)
Diplopia 1 (4%)
Ataxia 8 (28%)
Nystagmus 2 (7%)
Visual disturbances 2 (7%)
Intracranial hypertension signs 3 (10%)
Dysphagia 1 (4%)
*One contralateral.
imaging.
732 www.SCIENCEDIRECT.com
urgery for detection of complications, asostoperative blood collections or hydro-ephalus.
ESULTS
ostoperative evaluation was performed inhe first week after discharge, every 3 monthsfter surgery in the first year after operation,nd annually after the first year. MRI was ob-ained 4 to 6 months after surgery, and annu-lly in the following years. No patient was losto follow-up, and the mean follow-up timeas 39 months (4–73 months).
xtension of Surgical Removalll the tumors were completely removed insingle operation. Total removal was con-rmed in postoperative MRI in all cases
Figures 3 and 4). At the present time, therere no cases of tumor regrowth.
ortality and Morbidityhere were no perioperative deaths in thisroup of patients. Complications are summa-
ve and (B) postoperative magnetic resonance
n
WORLD NEUROSURGE
ized in Table 2. In four cases, surgery wasomplicated by postoperative cerebrospinaluid leaks. In one case, the fistula was nasalnd was surgically repaired. In the other threeatients, the leakage was local and was re-aired by surgery in one case and by lumbarrainage in two cases. A pseudomeningoceleeveloped in one patient, spontaneously re-olving in 5 to 6 months after surgery.
Two patients had meningitis in the postop-rative course, both treated with appropriatentibiotics. In one patient, there was pneu-onia, with need of ventilatory support for
ne week but resolving with antibiotic treat-ent. One patient had transient swallowing
roblems in the immediate days after surgery.here were no cases of postoperative bloodollection requiring surgical evacuation.
acial Nerve Outcomehe evaluation of facial nerve outcome, using
he House–Brackmann Facial Nerve Gradingystem (HB), was made 9 to 12 months afterurgery, except in three patients operated re-ently (Table 3) and in those submitted toypoglossal–facial anastomosis, evaluated 1
o 2 years after the anastomosis procedure.Anatomic preservation of facial nerve
as achieved in 25 cases (86%); in 4 of theseases, however, hypoglossal–facial anasto-osis was later needed, after verification of
bsence of functional recovery. In the 21atients who did not need anastomosis72%), facial function was excellent or goodHB I-II) in 13 cases (45%), fair (HB III) in 5ases (17%), and poor (HB IV) in 3 cases10%). In 2 patients (1 with HB III and 1 withB IV), further recovery must be expected
onsidering the short time since surgery.Hypoglossal–facial anastomosis was
erformed in eight cases (28%). In four pa-ients, the anastomosis was made immedi-tely after tumor surgery. In the other fourases, because of intraoperative impressionf anatomic continuity of the facial nerve,nastomosis was delayed 9 –12 months. Fa-ial function outcome was fair (HB III) inhree cases (10%), poor (HB IV) in threeases (10%), and with severe disability (HB) in one case (4%). In one patient, thereas been no facial function but the timeince surgery is still short for recovery.
earing Outcomeearing was evaluated using the New Han-
peratiover Classification (Table 4), 3 months
RY, DOI:10.1016/j.wneu.2011.08.019
Figure 2. Giant acoustic neuroma: (A) preoperative and (B) postoperative magnetic resonance imaging.
Figure 3. Giant cystic acoustic neuroma: (A) preoperative and (B) postoperative magnetic resonance imaging.
PEER-REVIEW REPORTS
JOANA SILVA ET AL. SURGICAL REMOVAL OF GIANT ACOUSTIC NEUROMAS
WORLD NEUROSURGERY 77 [5/6]: 731-735, MAY/JUNE 2012 ww
after surgery. Thirteen patients (45%) hadno hearing (H5) preoperatively, and no re-covery occurred after surgery. In four cases,there was poor hearing (H4) preoperativelyand all of them lost hearing after surgery.Twelve patients (41%) had useful (H2, fivecases) or moderate (H3, seven cases) hear-ing before operation. In these patients, al-though some degree of hearing loss oc-curred in all cases after surgery, it waspossible to preserve hearing function, withmoderate hearing (H3) after surgical re-moval of the tumors in seven cases (58%).
Evaluation of Preoperative NeurologicConditionsPresurgical facial dysesthesia, trigeminalneuralgia (ipsilateral and contralateral),and diplopia due to sixth-nerve palsy disap-peared in the first 4 to 12 weeks after sur-gery. Ataxia improved in all patients withsurgery, although in two cases there is apermanent slight gait disturbance. Nystag-mus disappeared after surgery.
Preexisting swallowing problems were re-solved in the first weeks after tumor removal,without need for tracheostomy. Althoughsome degree of ventricular dilation was stillpresent in postoperative MRI, hydrocephalusimproved in all cases, without need for cere-brospinal fluid shunting. Visual problemsdue to hydrocephalus improved until normalvision in one case, but in the other patientthere was a permanent visual loss, with visionreduced to 10% in both eyes.
DISCUSSION
Giant acoustic neuromas produce neuro-logic symptoms not only due to the involve-ment of the cochlear nerve but also to thedysfunction of other cranial nerves, especiallythe trigeminal and lower cranial nerves, com-pression of the cerebellum and brainstem,and intracranial hypertension (2, 9, 14). Sur-gical removal of the tumor is the best treat-ment and the only option in most cases (14).
The size of the tumor increases the diffi-culty of surgery in regard to the possibilities oftotal removal and the rate of complications (3,13, 16). Hearing and facial nerve functionalpreservation are also more difficult when thetumor reaches huge dimensions (2, 5, 14, 17).With the objective of improving the outcomein giant tumors, several treatment strategies
have been proposed, such as tumor stagedw.WORLDNEUROSURGERY.org 733
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PEER-REVIEW REPORTS
JOANA SILVA ET AL. SURGICAL REMOVAL OF GIANT ACOUSTIC NEUROMAS
resection, partial resection followed by radio-surgery, and the use of combined approaches(4, 6, 11). Radiosurgery alone is seldom usedn huge acoustic tumors. Although the func-
Figure 4. Giant acoustic neuroma: (A) preoperativ
Table 2. Postoperative Complications
Nasal CSF Leaks 1 (3.5%)*
Local CSF leaks 3 (10%)†
Meningitis 2 (7%)
Lower cranial nerve dysfunction 1 (3.5%)
Pneumonia 1 (3.51%)
Pseudomeningocele 1 (3.5%)
Total 9 (31%)
CSF, cerebrospinal fluid.*Surgical repair.
†Two lumbar drainages, one surgical repair.734 www.SCIENCEDIRECT.com
ional results are acceptable, complications ofreatment are considerable, especially withrigeminal nerve neuropathy, and the rate ofumor control is low, compared with that ob-
(B) postoperative magnetic resonance imaging.
Table 3. Postoperative Facial Function Ev
HB I (normal function)
HB II (slight dysfunction)
HB III (moderate dysfunction)
HB IV (moderately severe dysfunction)
HB V (severe dysfunction)
HB VI (total dysfunction)
HB, House-Brackmann grading system.
*One patient with expectable further improvement.WORLD NEUROSURGE
ained for smaller tumors. Mandl et al. re-orted a maintenance of pretreatment hear-
ng of 30% and a facial preservation rate of0% in 25 consecutive patients with acousticeuromas larger than 3.0 cm, who were
reated with stereotactic radiotherapy or ste-eotactic radiosurgery, but with significantates of trigeminal and abducens nerves neu-opathy and tumor progression in 16 % of theases (8).Yang, in a series of 65 patients withumors with maximum diameter between 30nd 40 mm, reports excellent results in facialunction and hearing preservation, but with a% rate of trigeminal sensory dysfunction and1% rate of growing tumors, 2 years afterreatment with stereotactic radiosurgery (18).artial resection of the tumor followed by ste-eotactic radiosurgery has also been proposedor treatment of giant acoustic neuromas.wai, in a series of 14 cases with a diameteretween 30 a 58 mm, reports an excellent fa-ial nerve function (House & Brackmannrade I or II) in 12 patients (85.7%) after treat-ent, but, in the mean follow -up period of 32onths, tumor size increased in 3 of the 14
atients (6). Other authors report good func-ional results in small series of patients buturther cases are needed to access the rate ofong term tumor growth control with thisombined treatment (4, 10).
In this series, total removal of the tumoras possible in a single operation, withoutortality and an acceptable rate of serious
omplications. Postoperative managementn a Neurocritical Care Unit is an importantactor in the outcome of these patients (13)nd, in fact, the complication rate was sig-ificant (31%), but there was a very goodvolution in all cases.
Facial nerve function can be preserved inost cases (2, 14, 19). In this series, and con-
idering the patients that did not need hypo-
tion (House–Brackmann scale [HB])
nastomosis XII-VII Anastomosis
4 (14%) 0
9 (31%) 0
5 (17%)* 3 (10%)
3 (10%)* 3 (10%)
0 1 (4%)
0 1 (4%)*
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PEER-REVIEW REPORTS
JOANA SILVA ET AL. SURGICAL REMOVAL OF GIANT ACOUSTIC NEUROMAS
glossal-facial anastomosis, the facial functionwas preserved in 72% of the cases and wasexcellent, good, or fair in 62% of the cases.Nevertheless, an improvement in facial nervepreservation rate must be achieved, and willprobably be possible with developments inneuromonitoring. Electromyography of thefacial nerve, currently used in acoustic neu-roma surgery, is a very important tool for in-traoperative localization of facial nerve, but itsvalue for determination of postoperative fa-cial function is not well established (15).Computerized analysis of the intraoperativefacial nerve electromyogram, with real-timemonitoring of pathologic patterns duringsurgery (12), and facial motor evoked poten-tials (1), may have a predictive value concern-ing postoperative facial nerve function, and itsapplication during surgery may have an im-portant contribution for facial nerve outcomeimprovement.
Hearing preservation is an important is-sue in giant acoustic neuroma manage-ment. As expected, most patients pre-sented with no hearing or poor hearing.Nevertheless, in 58% of the patients withpreoperative useful or moderate hearing(H2 and H3), preservation was possible,even if there was some degree of hearingloss in all cases and maintenance of pre-surgical hearing level could not beachieved. This possibility of hearing pres-ervation is important if a decision must bemade concerning the alternatives of treat-ment (14, 17).
Most preoperative neurologic symptomsand hydrocephalus improved or disap-peared after surgery. Special attention isnecessary concerning visual disturbances,because long-term hydrocephalus can pre-
Table 4. Hearing Function Pre- and PostoClassification)
Preoperative Hearing Level(number of cases)
H1 (normal hearing) —
H2 (useful hearing) 5
H3 (moderate hearing) 7
H4 (poor hearing) 4
H5 (no hearing) 13
clude visual recovery.
WORLD NEUROSURGERY 77 [5/6]: 731-7
ONCLUSION
omplete removal of giant acoustic neuro-as in a single operation, with no mortality
nd acceptable morbidity, is possible inost cases and facial function and hearing
reservation should be attempted. An expe-ienced surgical team and high standards ofostoperative care and neuromonitoringre the most important factors for a goodutcome in these patients.
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onflict of interest statement: The authors declare that theesearch was conducted in the absence of any commercialr financial relationships that could be construed as aotential conflict of interest.
eceived 15 March 2011; accepted 12 August 2011
itation: World Neurosurg. (2012) 77, 5/6:731-735.OI: 10.1016/j.wneu.2011.08.019
ournal homepage: www.WORLDNEUROSURGERY.org
vailable online: www.sciencedirect.com
pera
878-8750/$ - see front matter © 2012 Elsevier Inc.ll rights reserved.
w.WORLDNEUROSURGERY.org 735