Acta Neurochir (Wien) (2007) 149: 647–660 DOI 10.1007/s00701-007-1179-0 Printed in The Netherlands

Review Article Treatment of vestibular . Why, when and how?

E. Myrseth1, P.-H. Pedersen1, P. Møller2, and M. Lund-Johansen1

1 Department of Neurosurgery, Institute of Surgical Science, Haukeland University Hospital, University of Bergen, Bergen, Norway 2 Department of Otorhinolaryngology, Institute of Surgical Science, Haukeland University Hospital, University of Bergen, Bergen, Norway

Received July 13, 2006; accepted February 8, 2007; published online June 11, 2007 # Springer-Verlag 2007

Summary Introduction Sporadic vestibular (VS) causes unilat- Vestibular schwannoma (VS) is a benign tumour aris- eral , , and unsteadiness. In ing from the Schwann cells in the vestibular component many cases, the tumour size may remain unchanged for of the statoacoustic nerve. The clinical incidence rate many years following diagnosis, which is typically made is 10–15 per million=year [45, 76, 79, 129], but the by MRI. In the majority of cases the tumour is small, widespread use of MRI may lead to detection of more leaving the clinician and patient with the options of ei- tumours and an increase in incidence. Post-mortem dis- ther serial scanning or active treatment by gamma knife sections of temporal bones have shown the incidence of radiosurgery (GKR) or microneurosurgery. Despite the small tumours to be much higher (0, 9%) possibly due vast number of published treatment reports, compara- to selection bias [124, 130]. In an unselected autopsy tive studies are few, and evidence is no better than class material of 298 temporal bones, no tumours were found III (May, 2006). The predominant clinical endpoints of [21, 53]. VS treatment include tumour control, facial nerve func- The diagnosis of VS is usually made in adults with a tion and hearing preservation. Less focus has been put mean age ranging from 46 to 58 years in various series on symptom relief and health-related quality of life [37, 74, 84, 110, 140]. VS is rarely found in teenagers, (QOL). It is uncertain if treating a small tumour leaves and in these cases the tumour is often associated with the patient with a better chance of obtaining relief from neurofibromatosis type 2 (NF-2). future hearing loss, vertigo or tinnitus than by observ- Surgical treatment of VS has been one of the most ing it without treatment. Recent data indicate that QOL challenging procedures of neurosurgical practice for is reduced in untreated VS patients, and may differ be- more than a century. In 1894 Charles Ballance was prob- tween patients who have been operated and patients ably the first surgeon to remove a VS, and in the surgical treated with GKR. In the present paper we review the report he described the difficulties of getting his index natural course and complaints of untreated VS patients, finger around the tumour to achieve removal. The patient and the treatment alternatives and results. Furthermore, was still alive twelve years later although with fifth and we review the literature concerning quality of life in pa- seventh nerve palsies. tients with VS. Finally, we present our experience with Concerned about the high morbidity and mortality a management strategy applied to more than 300 cases of early VS surgery, Cushing advocated intracapsular since 2001. tumour debulking. As standards of neurosurgery and anaesthesiology improved, the concept of total tumour Keywords: Vestibular schwannoma; microsurgery; removal was reintroduced by Dandy. Olivecrona and radiosurgery; quality of life. 648 E. Myrseth et al. subsequent neurosurgeons contributed to further neuro- [10, 75, 80, 101, 107, 125, 134]. In a recent meta- surgical development by addressing facial nerve preser- analysis of VS growth, Yoshimoto found 22 retrospec- vation [36]. In the early 1960’s Bill House set a new tive and 4 prospective studies including 1340 patients standard by introducing the operating microscope as a [144]. The proportion of tumours showing growth valuable tool in VS surgery (for a review: see Ref. [72]). varied considerably, from 15 to 85% in the different In the early seventies Lars Leksell introduced Gamma reports (average 46%), and the mean growth rate knife radiosurgery (GKR), and it was demonstrated that was 1.2 mm=year during a mean observation period of GKR produced VS growth arrest or even involution. 38 months (range 6–64). Prospective studies, utilising Until December 2004, 28,306 VS patients had been MRI serial imaging showed tumour growth rates lower treated worldwide with GKR in 181 out of 213 reporting than the retrospective reports. Previous tumour growth centres (http:==www.elekta.com=). has been shown to represent a predictor for further Obvious as it may sound, it is nevertheless important growth and eventual treatment [10, 24]. Intracanalicular to remember that the treatment of any condition only can tumours seem to have lower growth rates than extra- be justified if the results of the treatment are better than canalicular lesions [101, 134], and a younger age is the natural course of the disease. There is a growing associated with more rapid tumour growth [74]. No debate on how VS can be best treated as it has become other reliable clinical or radiological predictors have clear that the tumour may remain unchanged in size for been found [101, 116, 123, 134]; for instance, the cli- years following diagnosis. A careful follow-up by MRI, nical growth index, as measured by the length of his- so-called ‘‘wait and scan’’, has therefore emerged as a tory divided by the maximum tumour diameter, did safe way of management in VS patients with small and not associate with growth. Using volume estimations medium-sized tumours. Thus, newly diagnosed VS may Mohyuddin et al. found a doubling time of 1.65 years be managed by three principally different approaches. (range 20.9–46.3 months) in 50 VS patients [80]. The options are, ‘‘wait and scan’’, GKR or surgical re- Modern neuroimaging software programs allow on- section, and the decision needs to be made whether screen volume estimation, which may improve future active treatment is indicated and which method of inter- studies of tumour growth [21]. vention is appropriate. VS treatment has traditionally focused on tumour Cochlear nerve symptoms control and preservation of cranial nerve function. During recent years however, health related quality of Unilateral hearing loss life (HRQOL) has emerged as a new issue in caretaking The most common symptom of VS is reduced hearing of VS patients, addressing outcome factors other than on the affected side (Table 1). When hearing is mea- traditionally used endpoints. This research has given sured, it is necessary to quantify both pure tone audio- information about the patient’s perception of the dis- metry and speech discrimination and the results obtained ease and treatment in relation to daily activities and are frequently classified using the Gardner-Robertson overall well-being. scale [35]. On admission, about 95% of patients report In the present article we review relevant data which unilateral hearing impairment. Audiometry shows that may serve as a premise for future debate about VS treat- serviceable hearing (Gardner-Robertson grade A þ B ment. This includes the clinical features and HRQOL in or class A1 þ A2 according to the Nordstadt Classifica- VS patients managed by ‘‘wait and scan’’, GKR, or surgi- cal resection. Finally, we discuss treatment algorithms for VS patients and present our own management strategy. Table 1. Symptoms at onset and on admission in 301 patients with vestibular schwannoma referred to the oto-neurosurgical group at Haukeland University Hospital 2001–2005

Natural history %% Presenting On admission

Tumour growth Reduced hearing 60.1 92.3 Tinnitus 32.7 69.5 The growth pattern of VS is highly variable, ranging Vertigo 23.4 42.5 from spontaneous involution [66] to rapid growth [46]. Unsteadiness 11.9 38.9 The tumours usually grow slowly or remain unchanged There is an increase in frequency of symptoms during the interval for years or growth may progress in a stepwise pattern between onset and admission. Treatment of vestibular schwannomas 649

Table 2. Hearing acuity on admission, both ears, according to the vertigo, and unsteadiness [54, 55, 74]. Dizzi- Gardner-Robertson grading scheme in 298 out of 301 patients with vestibular schwannoma ness is a common complaint, over time affecting up to 20–30% of individuals in the general population [87]. Grade Tumour ear (%) Contralateral ear(%) The incidence of true vestibular vertigo is approximately A 22.3 90.9 5% and is distinguished from other types of dizziness by B 26.3 7.3 a sensation of movement. It is a result of a mismatch C 14.2 1.1 between the vestibular, visual, and somato-sensory sys- D 37.2 0.7 tems. Since the functional ranges of these systems over- lap, it permits partial compensation of their individual tion) is present in about 50% of patients at diagnosis deficiencies [16, 25]. Vertigo may be constant or in- (Table 2). According to large series, the mean duration termittent, ‘‘nautical’’ (feeling like being on a ship), or of gradual hearing loss before diagnosis is about 4 years rotatory. Vertigo is associated with a significant reduc- [74, 83]. Increased age associates significantly with hear- tion in HRQOL [29, 83, 142]. Vertigo is difficult to ing disability in untreated VS patients [74]. Typically, quantify by objective means but self-reporting instru- hearing loss develops gradually, but an acute onset is ments such as an impairment index or a VAS scale found in 12–22% of patients [74, 77, 93]. The possible may be used [96]. aetiological factors in these patients include a conduc- tion block of the cochlear nerve or vascular compression Unsteadiness within the internal auditory canal (IAC) by a tumour arising laterally. VS is rarely the cause of sudden deaf- About 40–50% of VS patients (Table 1), report un- ness, as shown in the study by Saunders and co-workers, steadiness at diagnosis [19, 83]. In the study by Matthies who found only 13 cases of VS among 836 such patients and Samii, balance testing with eyes closed had the [119]. Patients suffering from sudden hearing loss seek highest rates of pathological findings in Class T1 (purely medical attention early, and have a shorter clinical history intrameatal) and T4 (compressing the brain stem) tu- than patients in whom the hearing loss is gradual [77, 93]. mours. Vestibular nerve signs were most pronounced in Class T1, and cerebellar signs in Class T4 tumours Tinnitus [74]. Sway motion can be measured by monitoring path length and speed, or area of sway on a balance platform Subjective tinnitus is a false perception of sound in [91]. Usually, values increase when the subject is tested the absence of an acoustic stimulus [62]. In a prevalence with eyes closed, and the ratio between results obtained study, 2.6% of the responders reported severe tinnitus when testing with open and closed eyes, the so called [4]. Tinnitus associates with age, and is more common Romberg Index, may be calculated. A modern stabilome- in men than in women affecting approximately 11% of try platform, such as the Equi-Test+ system (Neurocom, men between age 64 and 75 years [62]. Tinnitus may be Clackamas, OR, USA), enables the investigator to dis- present in a deaf ear, supporting the hypothesis of a criminate vestibular from other causes of unsteadiness. central pathophysiological origin. It is the second most In addition, results are automatically compared with frequent symptom in VS patients, occurring in 63–75% built-in age-adjusted reference data. The path lengths [74, 83, 84] of patients (Table 1) and in one third of of VS patients are significantly longer than those of those affected the symptom is intermittent. normal subjects [83] especially when tested with eyes Tinnitus may be inversely proportional with tumour closed [19]. Thus, the reduced vestibular function in VS size [74, 83], and is associated with depression [105]. patients seems to be partially compensated by vision. The intensity of tinnitus may be quantified subjective- ly by self-reporting questionnaires, such as the Tinnitus Impairment Index or a visual analogue scale (VAS) in- Other symptoms and clinical findings dex [8, 68, 105]. Preoperative headache was recalled by one third of operated VS patients in a large retrospective cohort Vestibular nerve symptoms study [109, 110], and by 18% in a Finnish study [55]. In our prospective material, 42 out of 301 patients (14%) Vertigo complained of headache, in 17 patients this was reported Vestibular nerve symptoms are found in 40–60% of as a ‘‘fullness’’ or pressure in the ear region ipsilateral to VS patients (Table 1) who may report a combination of the tumour. Since headache is a very common symptom 650 E. Myrseth et al.

Table 3. Other neurological findings in 301 patients with vestibular Table 4. Tumour length along the pyramid in 301 patients with vestib- schwannoma ular schwannoma

Impaired sensation in face 11.0% Tumour size (mm) Impaired corneal reflex 5.9% Reduced taste 5.2% Canalicular 28.6% Pyramidal signs 2.1% <10 16.3% 11–20 33.9% 21–30 12.9% >30 8.3% and there are no studies comparing headache in VS patients and a control group, it is uncertain whether headache is associated with untreated VS. angle (CPA), whereas tumour volumes were statistically A small proportion of newly diagnosed patients have similar in patients with or without tinnitus or vertigo gait disturbances or ataxia caused by hydrocephalus or [83]. In conclusion, many patients with useful hearing compression of the brainstem and cerebellum. In addi- may loose it during conservative management. The de- tion, cranial nerve deficits, usually facial numbness and velopment of other complaints is less known. occasionally diplopia and dysphagia may be found [74, 83], usually associated with large tumours (Table 3). Treatment

Symptom progression Conservative management (‘‘wait and scan’’: watchful waiting) Knowledge about the onset and development of com- plaints in VS patients is important when providing The concept of ‘‘wait and scan’’ is based on two advice on conservative management. In addition, this principles. First, a high proportion of the tumours do knowledge is necessary to evaluate how treatment com- not grow following diagnosis. Second, there is little evi- pares with the natural course of the tumour. Studies in- dence that treatment of a non-growing lesion is benefi- dicate that between one third [141] and one half [123] of cial to the patient, but well documented that treatment, conservatively managed VS patients loose useful hear- in particular surgery, may cause additional complaints. ing over a period of three years. Thus patients managed Therefore, in spite of increasing hearing loss in many conservatively are definitely at risk of developing hear- patients, conservative treatment may be a reasonable ing loss. Our current knowledge about further symptom option for patients with small to medium-sized tumours. development during ‘‘wait -and scan’’ is scarce, and For the ‘‘wait and scan’’ strategy to be successful, pa- cannot be predicted to the individual patient. However, tient compliance needs to be high and the follow up progression from onset to diagnosis is recalled by pa- program meticulous [116, 123]. This is illustrated in tients in several studies [55, 74]. In the 301 patients two elderly patients who were referred to us during last referred to us during the years 2001–2005, the median year. In both, the tumour had been known for several duration of symptoms at diagnosis was 26 months (mean years, but the follow up had been incomplete and both 51). The patients report an increase in frequency of developed gait difficulties due to brainstem compression symptoms during the time interval from onset to diag- from a growing tumour. Such instances may be classified nosis (Table 1). In a recent study of 199 untreated pa- as complications of the ‘‘wait and scan’’ approach. tients examined from 2001 out 2004 we found that the Any progression of symptoms, such as hearing loss, average length of the history was similar in patients with may be considered a failure of conservative treatment. a combination of complaints and in patients presenting We believe that prospective studies need to be carried with hearing loss alone [83]. It is reported that symp- out before patients can be advised on a statistical basis toms and tumour growth may progress independently about the relative merits of conservative management or [134]. Although hearing impairment may associate with GKR in relation to hearing preservation. tumour growth, it may not be an indicator of growth. Failure, defined as conversion from ‘‘wait and scan’’ Tinnitus is reported to associate with small tumours, and to active treatment, is reported in 15–50% of patients in vestibular disturbance with intrameatal lesions as well as various studies [24, 85, 123, 141]. The authors do not large tumours compressing the brain stem [74]. In our report in detail why failure occurred, but tumour growth, study, we found that unsteadiness associated with large increasing symptoms and patients’ own preference were tumour size (more than 20 mm) in the cerebellopontine probably the main reasons. Treatment of vestibular schwannomas 651

Surgery response system by Medtronic Xomed, Jacksonville, FL, USA), we have found that a stimulus of 0.10–0.20 mA VS surgery is technically challenging, and several generating normal signals indicates a good prognostic studies report on a gradual learning curve [17, 27, 52, sign for normal post-operative facial nerve function. If 78, 136]. The translabyrinthine (TL) and the suboc- the signals disappear in the medial portion of the nerve cipital=retrosigmoid (SO=RS) approaches can be used permanent facial nerve palsy may be expected, even if for all tumour sizes, whereas the middle cranial fossa signals in the intracanalicular nerve segment are normal. (MCF) approach is useful only for removal of intraca- It has been claimed that because the facial nerve is nalicular=small tumours. Hearing preservation can be detected earlier during surgery it is more easily saved by achieved only through the SO=RS and MCF approaches. the TL than by the SO=RS approach [14, 133], but evi- In many centres, VS patients are operated by an multi- dence for this is difficult to find in published literature, disciplinary team consisting of neurosurgeons and neu- as the functional results of both methods are within rootologists [23, 84, 128], and the approach is chosen the same range [3, 14, 23, 58, 84, 90, 115, 139, 143]. based on criteria such as tumour size, tumour extension, Patients with small tumours (including intrameatal) who preoperative hearing level, and the surgeon’s experience. undergo the MCF approach may have a less favourable facial nerve outcome than those operated by the SO=RS Tumour control or TL approaches [117], because the facial nerve is In a review of 38 studies including a total of 5005 op- located superior to the tumour which usually arises from erated patients and 1475 treated with GKR, Yamakami the inferior vestibular nerve in the internal auditory and co-workers found on average 96% total tumour canal. When drilling into the IAC from above, the sur- removal after microsurgery. The tumour recurrence rate geon’s view of the tumour is obstructed by the facial was 1.8%, which compared favourably with the recur- nerve, which then becomes vulnerable to manipulation rence rates following radiosurgery and tumour pro- during tumour resection. gression following conservative treatment [141]. Some Facial nerve transection is reported to occur in 2.5– authors recommend subtotal tumour resection with sub- 7% [23, 26, 114, 115] of surgical procedures. Immediate sequent GKR if a total resection puts the facial nerve intracranial nerve repair should be attempted in such function at a high risk [50], a strategy which is also situations using a free graft from the great auricular or advocated by our group. Due to inadequate access to the sural nerve. the lateral part of the internal auditory canal, the RS=SO Even in patients in whom the seventh nerve is anato- approach is claimed to be associated with a higher rate mically and physiologically intact at closure, paresis in- of tumour recurrence than the TL approach [143], but creasing to complete palsy may develop during the early this has not been confirmed by comparative studies. post-operative period. Usually, nerve function improves gradually over the next few months. In patients with post- Facial nerve preservation operative facial nerve palsy, careful attention to the eye is necessary to prevent infection and erosions of the cornea Second only to tumour removal, facial nerve preser- caused by the impairment of eyelid closure. A tarsorraphy vation is the main goal of VS surgery. There are several or insertion of a gold weight or spring in the upper eyelid grading systems for the evaluation of facial nerve func- will assist to protect the eye in these patients. When facial tion, the most widely used being the House-Brackmann nerve function does not recover, reconstructive surgery by scale [44] which provides a useful assessment tool. The hypoglossal-facial or cross-face facial nerve anastomosis scale is subjective and inter-observer variation is docu- (with nerve graft) are the alternative methods of treat- mented [20, 103]. In addition, the study by Martin and ment. Either method may establish facial nerve function co-workers demonstrates that patients score their own equivalent to House-Brackmann grade 3 in 61–79% of facial function as being a poorer grade than assessed the patients [26]. In long lasting facial nerve palsies re- by the surgeons [73]. The size of the tumour and the construction of facial symmetry is achieved through var- surgeon’s experience are the pre-operative predictors of ious face-lift cosmetic procedures. facial nerve outcome [11, 84, 114, 128]. In modern sur- gical practice per-operative facial nerve EMG is man- Hearing preservation datory for anatomical and physiological monitoring, and provides a reliable predictor of post-operative func- Post-operative hearing preservation correlates strong- tion [39, 49, 73, 86]. In our experience (using the Nim- ly with tumour size. In 1986, Glasscock et al. stated that 652 E. Myrseth et al. preservation of hearing is unlikely when the tumour is Similarly, studies reporting on post-operative vertigo larger than 20 mm [38]. Yates et al. obtained no hearing are few, and prospective studies with baseline registra- preservation in tumours 25 mm in the CPA, and Tonn tion of symptom severity by VAS or impairment index et al. had no hearing better than Gardner-Robertson questionnaires seem to be lacking. Lynn et al. assessed grade D in tumours larger than 30 mm in the CPA post-operative dysequilibrium (imbalance, vertigo, and [128, 143]. However, Samii and Matthies report good light-headedness) in 237 VS patients operated by the post-operative hearing preservation for a proportion of SO=RS approach [69]. In this series, 65% reported dys- larger tumours [113]. equilibrium between 3 months and 7 years after surgery Sanna and co-workers preserved hearing of class A or although with a mild impact on QOL. In the questionnaire B, i.e. functional hearing according to the AAO-HNS study by Wiegand et al. [138], 9% of patients reported grading scheme, in one third of patients operated by post-operative dysequilibrium as a severe handicap and the SO=RS approach (tumors <20 mm in the CPA) or only 10% reported normal function. In the prospective the MCF approach (tumour extending <5 mm into the part of Levo et al.’s study [60], the sway velocity in- CPA). Reviewing published series where patients had creased after the operation, and had not returned to pre- been operated through the SO=RS and MCF approaches operative values one year after surgery indicating an to preserve hearing, the authors pointed out that their increase of vestibular complaints. Multivariate analysis own complication rates of the latter were higher than revealed that the TL approach, rehabilitation, low age in patients operated by the TL approach. They con- and preserved facial nerve function predicted a good cluded that attempts at hearing preservation should be outcome for postural stability. Patients operated by the measured against the added risk of complications during SO=RS approach and diagnosed with depression were at these procedures [117]. risk of developing postoperative gait difficulties. In comparison with historical data, the intraoperative In conclusion, most of our knowledge about the effect monitoring of cranial motor nerves and continuous re- of VS surgery on tinnitus and vertigo derives from retro- cording of brain stem auditory evoked potentials (BAEP) spective studies. Prospective studies with careful base- substantially improves the outcome of hearing function line recordings may provide further insight into these [113, 128]. problems.

Post-operative tinnitus, vertigo and unsteadiness Postoperative headache Only a few retrospective studies address the impact of In the study by Ryzenman and co-workers, 42% of VS surgery on tinnitus. The study by Baguley et al. in- operated patients reported headache which was usually vestigating pre-and post-operative tinnitus among 129 mild. Women, especially of a younger age, were more patients, indicates a favourable effect with TL tumour affected than men. During the first year after surgery, the removal [5]. The authors found that patients with no SO approach was associated with headache more than tinnitus preoperatively were unlikely to develop it, and the MCA and TL approaches, but this difference disap- mild or moderate tinnitus did usually remain unchanged, peared later. Tumour size did not associate with post- or it became less intense whereas severe tinnitus im- operative headache [110]. proved in some patients. In a study addressing HRQOL In our experience, postoperative headache is not a and the severity of tinnitus in a cohort of 51 operated VS major problem in VS patients. We do not specifically patients, post-operative tinnitus did not correlate with address postoperative headache in our postoperative sur- tumour size or age [28]. The authors concluded that vey, but ask if there are any complaints other than the post-operative tinnitus status was unpredictable, but, in cardinal symptoms. We routinely use craniotomy with contrast to the results reported by Baguley et al., there replacement of a free bone flap. Some studies indicate was a slight overall increase in patients reporting tinnitus that a standard craniectomy may be associated with sig- after surgery. Similar to our results [83], the authors nificant postoperative headache, which may be reduced found that tinnitus did not interfere with HRQOL mea- with minimal bone removal during craniectomy [42, 51, sured by the GBI questionnaire. Andersson and co- 56, 118]. workers concluded that among 141 patients operated, Other complications and mortality tinnitus was usually mild, and the likelihood of an im- provement or worsening after surgery was low [2] and Improvements of surgical technique and refinements similar results were found by others [11, 138]. in anaesthesiology have reduced the mortality from more Treatment of vestibular schwannomas 653 than 25% in the hands of the early neurosurgical pio- free survival of 92% indicates that recurrences develop neers to 0–2% in the most recent series. In most patients during the first three years [43]. The tumour growth rates the cause of death is postoperative cardiopulmonary before GKR (or surgery) are usually unknown in re- complications [14, 23, 26, 41, 84, 112, 128, 141]. ported series. Consequently, a proportion of treated tu- Apart from hearing loss and facial nerve dysfunction, mours might have remained unchanged without any CSF leakage is the most frequent postoperative com- treatment at all. plication, occurring in 3–15% of cases [14, 26, 41, 59, 112, 128]. Usually the CSF leak resolves after temporary Effect on symptoms lumbar drainage, leaving only a small number requiring a secondary procedure. The frequency of postoperative Hearing preservation according to the Gardner- meningitis is about 1–3% [14, 26, 112, 128]. Robertson scale (grade A–C) is reported in 50% to 89% Cranial nerve or brainstem dysfunction is an infre- of patients undergoing GKR [31, 82, 94, 102, 116]. In quent postoperative problem, but may be found in pa- our own retrospective material, the frequency of hearing tients with large tumors [15, 41, 59, 112]. loss was higher [84]. This may be due to variation in radiation doses, but may as well be related to differences in tumour volume and configuration. For instance, re- Gamma knife radiosurgery (GKR) ports indicate that the risk of facial nerve dysfunction Dose and tumour control may correspond to the length of the nerve irradiated, tumour diameter and the dose delivered to the brainstem 60 The Gamma knife consists of 201 Cobalt sources [30, 34, 61]. which are arranged in a hemisphere. Beams from the ra- In the literature covering GKR of VS, the main focus dioactive sources are directed through collimators and of interest has been on tumour control and hearing pre- converge to a common target. By individual plugging of servation. The effect on tinnitus and vertigo is largely 60 collimators or weighting the different Cobalt sources unknown. More knowledge about this is of interest, as the radiosurgeon can shape a three-dimensional radia- reports indicate that in particular vertigo causes consid- tion field similar to the lesion. Ideally, a single dose of erable discomfort and leads to impairment of quality of radiation sufficient to stop further growth may be admin- life [83, 87, 96, 142]. istered to the lesion, while the dose delivered to adjacent structures is much lower and therefore tolerable. Complications Usually, the dose to the tumour margin is the primary radiophysical parameter during dose planning. Although The risk of facial nerve dysfunction has gradually there is no consensus about the optimal dose, high rates decreased from approximately 30% in early series, to of tumour control with preservation of normal structures 1–4% [31, 33, 82, 131]. Facial nerve function of grade can be achieved with a margin dose of 12 Gy. Maximum 1 or 2 according to the House-Brackmann system may doses of 20–25 Gy to the tumour centre are effective, but therefore be expected in more than 96% of patients [67, there is a tendency nowadays to reduce the maximum 97, 131]. Similarly, trigeminal nerve function can be doses [32, 131, 132]. In order to obtain a margin dose of preserved in 95–97%, and as the prescribed dose to the 12 Gy and a maximum dose within accepted limits, the tumour margin has been gradually lowered, post-irra- maximum tumour diameter should not exceed approxi- diation trigeminal dysfunction is now rare [31, 32, 97]. mately 30 mm. However, a recent study shows beneficial Hydrocephalus may develop in 2–4% of VS patients effect of low-dose GKR in a series of larger tumours, up treated by GKR [84, 92], and it should be suspected in a to 40 mm [47]. patient complaining of unsteadiness developing months GKR has been used for more than three decades, and or years after treatment. The underlying mechanism is worldwide an increasing number of VS patients receive uncertain, but it may be seen in medium-sized tumours, treatment by GKR instead of surgery. The aim of GKR and thus is unrelated to CSF obstruction. Since it may is tumour control, defined as either reduced or un- also be seen in some untreated medium-sized tumours, changed tumour volume. The majority of centres report the contribution of GKR to hydrocephalus development tumour control rates between 89 and 100%, but few in VS patients is uncertain [106]. report observation periods longer than five years. There- Post-GKR neoplasia, either as a second tumour or a fore, late regrowth may alter these figures, although a malignant change in the treated lesion has been reported recent long-term series showing a 10-year progression- in a few cases [6, 40, 57, 63, 121, 122]. It is to be 654 E. Myrseth et al. expected that among the large number of patients treated grouped according to tumour size, tinnitus or reduced worldwide by GKR for benign lesions, some will de- hearing, less difference between groups was seen in the velop a malignant brain tumour or a at a reported QOL [83]. later stage. Meningioma is the intracranial neoplasm Most of our knowledge about QOL in VS patients usually associated with previous irradiation [18, 111], derives from retrospective studies of patients who re- but an association with previous GKR has not been ceived treatment (usually surgery) several years earlier. documented. The responders usually reported QOL lower than norms. Somewhat surprisingly, poor facial nerve function as- sociates only weakly with a reduction in QOL [12, 73, Health-related quality of life in VS patients 84]. Only a few studies report on the QOL after GKR [84, 116]. In our study, we found a slightly better QOL Today, VS may be regarded as a chronic disease outcome in the GKR than in the surgery group [84]. In which is only rarely life-threatening. Instead, the tumour the study by Regis and co-workers comparing GKR and causes discomfort and leads to hearing loss. Therefore, surgery, the authors reported better QOL following GKR, information about HRQOL during the course of treat- but the questionnaires used were not validated [102]. ment and conservative management is highly relevant One may speculate that patients managed conserva- for this group of patients. Quality of life is measured tively are at risk of the QOL being reduced if treatment by validated generic or disease-specific questionnaires is necessary at a later stage because of a growing tu- and is increasingly being used as secondary and even mour. Two studies show that in patients who received primary endpoints in clinical studies [13, 126, 127]. treatment because conservative treatment failed, QOL Generic questionnaires, which are applicable for patients was no worse than in patients who received treatment with many conditions, allow comparisons between pa- initially [10, 116]. tient groups and a reference population [64, 65, 135]. When studying treatment of any disease, prospec- Some studies utilize questionnaires addressing symptoms tive pre-treatment baseline data are valuable. To our that are typically found in operated patients (see e.g. [1, knowledge, studies comparing QOL before and after 7,48,71,95,100,102,104,109,110,116,120,133,137] treatment, and during the course of conservative man- but to our knowledge a validated disease-specific ques- agement of VS seem to be lacking, and should be tionnaire has not been reported for VS. Instead, the gen- undertaken. eric questionnaires SF-36 [9, 12, 22, 70, 73, 83, 84] and Glasgow Benefit Inventory (GBI) [83, 84, 88, 116] pre- dominate. SF-36 can be used to distinguish among var- Treatment decision and clinical management ious stages of illness, and large scale reference data is available in many countries for comparison with age- Although the choice of treatment in VS patients is a and sex-matched controls. The GBI questionnaire requests controversial issue, the treatment decision process has the subject to compare QOL before and after a specific been poorly investigated. A recent study of 139 VS pa- event (for example the diagnosis or treatment of VS). tients managed at the Mayo Clinic showed that 23% of Three recent studies report on the QOL in untreated the patients chose ‘‘watchful waiting’’, 36% underwent VS patients [70, 83, 116]. In a study of patients managed GKR, and 40% underwent surgical tumour removal [98]. over a 15-year period, Sandoraam and co-workers dem- The authors found that the discipline of the attending onstrated that patients managed conservatively reported surgeon was a predictor for the choice of treatment, and better QOL than patients receiving GKR or microsur- small tumour size and high age were predictors for con- gery [116]. MacAndie and Crowther demonstrated that servative treatment. QOL in VS patients managed conservatively is similar As discussed before, the criteria for successful treat- to other patients with vestibulo-cochlear complaints [70]. ment of VS rely on tumour control rates and cranial In our prospective study of 199 untreated VS patients we nerve preservation. Despite the large amount of studies investigated the impact of symptoms and tumour size on concerning treatment results, studies comparing treat- QOL, which was below normative values across six out ment methods are based on no better than class 3 of eight subscales of SF-36. We found that the overall evidence [89], with one recent exception of class 2 predictor of reduced QOL in untreated VS patients was evidence showing better results (facial nerve function, vertigo, which discriminated QOL across all SF-36 and complications, hearing preservation) for GKR than two out of three GBI subscales. When patients were for surgery [99]. Few centres, if any, can offer VS patients Treatment of vestibular schwannomas 655 all available surgical methods and GKR. Clinicians rec- – <5% risk of shunt-requiring hydrocephalus. ommend a treatment modality depending on what is – Complaints and QOL probably unchanged. available at their institution, and will convey that to the – Very low risk of radiation-induced neoplasia. patients. It is our opinion that the alternatives ought to – No recovery period necessary. be presented to the patients in an unbiased fashion, and MS: then discussed thoroughly with them [108]. Moreover, patients are more knowledgeable about their disease and – Total tumour resection in more than 90%. treatment options than previously, and it is difficult to – GKR of growing residual tumour is possible. conduct prospective randomised studies. – Facial nerve function is dependent of tumour size; At the Haukeland University Hospital, Department 80% H-B grade 1 or 2. of Neurosurgery, the Gamma knife was established – Facial nerve reconstruction to HB grade 3 is possible. in 1988 as the 5th centre worldwide. During the next – Total hearing loss except in some small tumours. 12 years, a total of 219 Norwegian VS patients were – Complaints and QOL probably unchanged. treated, 103 with GKR, and 116 with microsurgery – Mortality <1%. [84]. Conservative treatment was used in a small num- – About 3 months to full recovery. ber of selected patients [81]. GKR or microsurgery was Until January 2006, 301 patients with VS referred to administered to tumours 30 mm, and microsurgery our unit (Fig. 1) have signed a written consent and thus > (MS) to tumours 30 mm in the CPA. The choice of been enrolled into a prospective research program on method depended on patient preference and the medi- cal condition. Patients with vertigo were predominantly treated with surgery. In 2001, we launched a new treatment algorithm di- viding patients into four categories, based on CPA tu- mour size and tumour growth: 1. <20 mm, single observation or no growth – Conser- vative management. 2. <20 mm and growth on serial scans – GKR or MS. 3. 20–25 mm, single observation – GKR or MS. 4. >25 mm – MS. Conservative management involves outpatient consul- tation and contrast axial=coronal thin slice MRI at 6 and 12 months and then annually. In a few elderly category 2 patients with growing canalicular tumours we adopted a ‘‘wait and scan’’ approach. Although we established a limit of 25 mm for recommending GKR, tumours up to 30 mm were treated in a few patients who had a strong wish to avoid surgery. In the elderly, or medically ill patients, a few even larger lesions have received GKR Fig. 1. Age distribution in 301 VS patients referred to the oto- treatment. These exceptions apart, the algorithm was neurosurgical group. Mean: 57.0 years applicable to nearly all patients. Patients in categories 2 and 3 received standardised Table 5. Primary and secondary treatment in 301 patients with ves- information given orally by one of the authors about tibular schwannoma (see text for details) treatment alternatives as follows: GKR: Primary management Secondary management Wait and scan 165 20 – 90–95% tumour control. GKS 81 3 – Later surgery possible, but probably more difficult Microsurgery 55 2 (in relation to dissection of VII nerve). Total 301 25 – Facial nerve palsy very rare. Indicates that following initial decision to wait and scan, either GKR – Gradual hearing loss may occur. or microsurgery were given to 20 (ten in each) patients. 656 E. Myrseth et al.

VS, approved by the regional Medical Ethical Commit- ting, was followed by a telephone consultation one to tee. Out of 165 patients who were initially included into two weeks later. The second important finding in this the wait and scan program, MS and GKR each were study is that GKR was preferred by a significantly higher given later to two groups of ten patients. During the proportion of patients than those choosing surgery. This period, 136 patients received primary treatment (55 with may not be surprising, since the complication rate is MS and 81 by GKR (Table 5). lower, no recovery period is necessary, and the risk of In order to investigate the choice of treatment in therapy failure is low and within the same range for both patients with newly diagnosed VS, we conducted a pro- alternatives. We think it is necessary to inform patients spective study during the years 2001 out 2005. Patients about both options of treatment, and let the patient de- with tumours 25 mm or less to be treated were presented cide, even if their preferred treatment is not an option with the options of either choosing treatment themselves available in the same institution. or undergoing randomisation. Information was presented about the treatment alternatives as above. If medical con- Conclusion ditions or age (70-year limit) contraindicated surgery, only GKR was used, and these patients were excluded. Vestibular schwannoma is a benign tumour which Data collection and analysis was carried out according usually either grows slowly or remains unchanged for to a pre-defined protocol. Out of 71 patients who ful- many years. The complaints are usually mild, and may filled the inclusion criteria, only seven patients accepted persist despite treatment. As the average size of newly randomisation. Altogether 64 consenting patients with diagnosed tumours is less than 20 mm, treatment is only tumours 25 mm or less did not accept randomisation rarely a life-saving procedure. Instead, treatment aims at but fulfilled the criteria for a free choice between GKR preventing morbidity caused by growth. Tumour control and surgery. Among the data collected in the period rate, facial nerve function and hearing preservation are 2001–2006, we analysed if one particular treatment the traditional endpoints of VS treatment, but vertigo, was preferred, or if any of the following, i.e., age, sex, unsteadiness, tinnitus and health-related quality of life tumour size or hearing function (Gardner–Robertson should be reported as well. There is definitely a need for A þ B grouped together against C þ D) were different prospective comparative studies. between the 2 groups. To be justified, VS treatment should lead to an out- Altogether 45 patients chose GKR and 19 surgery come better than the natural course. When treatment is (P<0.001), (Table 6). The groups did not differ signifi- indicated, surgery and Gamma Knife Radiosurgery are cantly in the distribution of any of the four parameters alternatives. Although prospective comparative studies tested. are lacking, both methods have a cure rate of 90–98% Several conclusions may be drawn from the above and patients should be informed about each alternative. study. First, since only seven patients accepted randomi- The original work presented here indicates that given sation, class I evidence for GKR versus MS for VS will balanced, unbiased information, a majority of patients require a randomised multicentre study. However, if prefer GKR if treatment is indicated. Consequently, the given the above information, patients may decide on questions ‘‘why, when and how’’ need to be discussed the treatment choice themselves. Although no prospec- with the patient before treatment is undertaken. tive data collection was used to investigate this, we observed that many patients needed more than one con- References sultation with the attending doctor. Frequently, the first 1. Andersson G, Ekvall L, Kinnefors A, Nyberg G, Rask-Andersen H consultation, which was carried out in an outpatient set- (1997) Evaluation of quality of life and symptoms after transla- byrinthine acoustic neuroma surgery. Am J Otol 18: 421–426 2. Andersson G, Kinnefors A, Ekvall L, Rask-Andersen H (1997) Table 6. Characteristics and individual treatment choice of 64 patients Tinnitus and translabyrinthine acoustic neuroma surgery. Audiol with VS Neurootol 2: 403–409 3. Arriaga MA, Chen DA (2001) Facial function in hearing pre- Gamma knife Surgery P servation acoustic neuroma surgery. 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patients with glioblastoma: a randomised controlled trial. Lancet tumours: hearing preservation. It is the result of improved microsurgery Oncol 6: 937–944 that the goalposts have moved, allowing hearing preservation to be the 128. Tonn JC, Schlake HP, Goldbrunner R, Milewski C, Helms J, relevant factor for those who present sufficiently early. Paradoxically, Roosen K (2000) Acoustic neuroma surgery as an interdisciplinary surgery is now undermined by the outcome of less invasive methods. approach: a neurosurgical series of 508 patients. J Neurol Neu- As most patients present with progressive hearing loss, despite the rosurg Psychiatry 69: 161–166 lack of high level statistical proof they suspect what the future holds 129. Tos M, Stangerup SE, Caye-Thomasen P, Tos T, Thomsen J (2004) without any intervention. At the same time they are increasingly aware What is the real incidence of vestibular schwannoma? Arch of the radiosurgical hearing preservation in large series [1, 2]. 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In this day and age it is quite pos- functional hearing after gamma knife surgery for vestibular sch- sible for patients to be referred to another centre (specialising in micro- wannoma. J Neurosurg 102 Suppl: 204–206 surgery of the skull base or radiosurgery) if necessary. In fact, it should 133. van Leeuwen JP, Braspenning JC, Meijer H, Cremers CW (1996). be considered negligent if such alternatives are not truly provided. The Quality of life after acoustic neuroma surgery. Ann Otol Rhinol study presented here is commendable for its detached and honest stan- Laryngol 105: 423–430 dardised patient information which makes their results credible. 134. Walsh RM, Bath AP, Bance ML, Keller A, Tator CH, Rutka JA (2000) The role of conservative management of vestibular sch- wannomas. Clin Otolaryngol Allied Sci 25: 28–39 References 135. Ware JE Jr (2000) SF-36 health survey update. Spine 25: 3130–3139 1. Regis J, Pellet W, Delsanti C, Dufour H, Roche PH, Thomassin 136. 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Wiet RJ, Mamikoglu B, Odom L, Hoistad DL (2001) Long-term In this comprehensive review, the authors discuss the spectrum of results of the first 500 cases of acoustic neuroma surgery. Otolar- clinical presentation for a vestibular schwannoma and the various man- yngol Head Neck Surg 124: 645–651 agement options. They provide a good overview of what is known 140. Wowra B, Muacevic A, Jess-Hempen A, Hempel JM, Muller- regarding the natural history for such tumors if untreated. We agree that Schunk S, Tonn JC (2005) Outpatient gamma knife surgery for this is a reasonable choice for older patients, who may not require any vestibular schwannoma: definition of the therapeutic profile based tumor care during their remaining life. However, for younger patients, on a 10-year experience. J Neurosurg 102 Suppl: 114–118 there is a growing experience showing that tumor irradiation may lead 141. Yamakami I, Uchino Y, Kobayashi E, Yamaura A (2003) Con- to better cranial nerve outcomes (i.e., hearing preservation) than ob- servative management, gamma-knife radiosurgery, and microsur- servation. Thus observation may not be a wise choice in a young patient. gery for acoustic neurinomas: a systematic review of outcome and As for the controversy over resection versus radiosurgery, there are risk of three therapeutic options. Neurol Res 25: 682–690 now four matched cohort studies, including one performed by these 142. Yardley L, Dibb B, Osborne G (2003) Factors associated with authors, showing similar or better outcomes in the Gamma knife radio- quality of life in Meniere’s disease. Clin Otolaryngol Allied Sci surgery patients. Although a randomized trial is not likely to be con- 28: 436–441 ducted, there is sound level two evidence supporting radiosurgery for 143. Yates PD, Jackler RK, Satar B, Pitts LH, Oghalai JS (2003) Is it smaller volume tumors. In addition, the long-term data for radiosurgery worthwhile to attempt hearing preservation in larger acoustic continues to be published [1]. We need such information for after all neuromas? Otol Neurotol 24: 460–464 forms of management. 144. Yoshimoto Y (2005) Systematic review of the natural history of vestibular schwannoma. J Neurosurg 103: 59–63 Reference 1. Kondziolka D, Nathoo N, Flickinger JC, Niranjan A, Maitz AH, Comments Lunsford LD (2003) Long-term results after radiosurgery for benign intracranial tumors. Neurosurgery 53: 815–822 The authors present an overview, much like a didactic chapter, for Douglas Kondziolka the presentation and management of acoustic neuromas on the apropos Pittsburgh of their study. As they allude to in the paper, the history of management of these tumours progressed from trying to save the patients’ life, to keeping the neurological deficit to the minimum. Initially surgeons were Correspondence: Dr. Erling Myrseth, Department of Neurosurgery, happy to just minimize the deficit to the cerebellum and brainstem, later Institute of Surgical Science, Haukeland University Hospital, University attempting and achieving increasing functional facial nerve preserva- of Bergen, N-5021 Bergen, Norway. e-mail: erling.myrseth@helse- tion, progressing to the current aim for many small and medium-sized bergen.no