Petroclival meningiomas resected via a combined ... · tactic radiosurgery (SRS) for newly diagnosed, incom-pletely resected, or recurrent tumor has gained increasing Petroclival

J Neurosurg Volume 122 • February 2015

cliNical articleJ Neurosurg 122:373–380, 2015

Petroclival meningiomas continue to present a sig-nificant technical challenge, and resection continues to carry a relatively high risk of neurological mor-

bidity in patients with these lesions because of the tumors’ proximity to cranial nerves, vascular structures, and the brainstem. A combined transpetrosal approach, which in-cludes various degrees of petrosal resection to minimize brain retraction and increase exposure to the petroclival

region, has been described for radical resection of these tumors.1,5–7,12,30,32 Despite the development of a variety of surgical techniques, however, this approach has not be-come widespread because of the high rates of morbidity and mortality during the early years of its use.1,4,21,23,29,32 Complete resection is sometimes not possible, and stereo-tactic radiosurgery (SRS) for newly diagnosed, incom-pletely resected, or recurrent tumor has gained increasing

Petroclival meningiomas resected via a combined transpetrosal approach: surgical outcomes in 60 cases and a new scoring system for clinical evaluationHiroki Morisako, MD, takeo Goto, MD, and Kenji Ohata, MD

Department of Neurosurgery, Osaka City University Graduate School of Medicine, Osaka, Japan

ObJect Petroclival meningiomas are among the most challenging intracranial tumors to treat surgically. Many skull base approaches have been described to improve resection and decrease patient morbidity. The authors undertook this study to evaluate the results of their treatment of petroclival meningiomas using objective measurements of tumor volume and a new impairment scoring system to assess neurological symptoms that severely affect the patient’s quality of life, such as impairment of swallowing and speaking, motor function, and consciousness and communication.MetHODs Between January 1990 and December 2009, the authors used a combined transpetrosal approach to treat 60 patients with benign (WHO Grade I) petroclival meningiomas. In this retrospective study, all 60 cases were analyzed in detail with regard to tumor volume, extent of resection (EOR), long-term tumor control, neurological outcome, and the patient condition. In addition, patients were divided into 2 groups according to the period during which the surgery was performed: the early group, from 1990 to 1999, and the late group, from 2000 to 2009. A new scoring system, the petroclival meningioma impairment scale (PCMIS), was created for quantitative assessment of 8 categories of neurologi-cal functions, with scores assigned in each category according to the level of disability and its impact on the patient. The PCMIS was used preoperatively, at 3 months after surgery, and at the time of the last follow-up examination, and the results for the 2 groups were compared.results There were 24 cases in the early group (1990–1999), and the mean duration of follow-up was 149.3 months. The mean EOR was 96.1%, and good long-term tumor control was obtained in 22 patients (91.7%). One of patients died because of a postoperative complication in the perioperative period. The PCMIS improved in 3 patients (12.5%), remained stable in 1 (4.2%), and worsened in 20 (83.3%). There were 36 cases in the late group (2000–2009), and the mean duration of follow-up was 77.9 months. The mean EOR was 92.7%, and good long-term tumor control was obtained in 34 patients (94.4%). The PCMIS score improved in 23 patients (63.9%), remained stable in 5 (13.9%), and worsened in 8 (22.2%).cONclusiONs The combined transpetrosal approach has provided satisfactory functional improvements and excel-lent tumor control for patients with petroclival meningiomas. The PCMIS provides a specific tool for quantitative assess-ment of the patient’s state.http://thejns.org/doi/abs/10.3171/2014.8.JNS132406KeY WOrDs petroclival meningioma; combined transpetrosal approach; surgical management; outcome; new scoring system; skull base

abbreviatiONs EOR = extent of resection; KPS = Karnofsky Performance Status; PCMIS = petroclival meningioma impairment scale; SRS = stereotactic radiosurgery.subMitteD October 29, 2013. accepteD August 26, 2014.iNcluDe WHeN citiNG Published online November 7, 2014; DOI: 10.3171/2014.8.JNS132406.DisclOsure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

373©AANS, 2015

H. Morisako, t. Goto, and K. Ohata


acceptance over the past decade.3,8,16,17,19,20,24,25,26,33,35 Be-cause these lesions often grow slowly and may produce symptoms only late in their course, the optimal treatment protocol remains controversial.

During the last 20 years, we have treated patients with medium- or large-sized petroclival meningiomas with sur-gery (maximum feasible resection) via a combined trans-petrosal approach followed by SRS if necessary. In this paper we present the results of our analysis of our con-secutive series of cases of petroclival meningioma. The re-sults are quantitatively evaluated with objective measure-ment of the tumor volume and a new impairment scoring system to assess the patient’s condition, the petroclival meningioma impairment scale (PCMIS).

MethodsBetween January 1990 and December 2009, 60 con-

secutive patients with benign (WHO Grade I) petroclival meningiomas underwent microsurgical resection via a combined transpetrosal approach at Osaka City Univer-sity. All cases were retrospectively analyzed for tumor volume, extent of resection (EOR), long-term tumor con-trol, neurological outcomes, and patient condition. A new scoring system, the PCMIS, was created for quantitative assessment of the patient’s state.

patient populationThe median age of the patients at the time of surgery

was 54.4 years (range 33–72 years), and there were 51 women and 9 men. For all cases, the mean follow-up pe-riod was 8 years and 10 months (range 0–231 months). Excluding 1 patient who died during the perioperative period, the mean follow-up was 13 years (range 98–231 months). All patients underwent neuroimaging and neu-rological follow-up at intervals of 6–12 months. Patients were divided into 2 groups for comparisons based on the timing of surgery: the early group, which included all pa-tients treated between 1990 and 1999 (n = 24), and the late group, which included all patients treated between 2000 and 2009 (n = 36).

Operative DetailsIn all patients, maximum possible resection via the

combined transpetrosal approach performed as the initial therapy by an experienced senior neurosurgeon. In the early group, retrolabyrinthine petrosectomy was applied in 7 cases and the labyrinth was drilled out in the other 17 patients. In the late group, retrolabyrinthine petrosectomy was applied in 30 cases and the labyrinth was drilled out to widen the surgical corridor in 6 patients with extremely large tumors. The internal auditory canals were opened in all 60 cases. All surgical procedures related to petro-sectomy were accomplished by members of our neurosur-gical staff. In the early group, gross-total resection was intentionally performed in an attempt at surgical cure of the disease despite the risk of neurological deficits, which occurred in some cases. In the late group, the degree of tu-mor resection was determined according to intraoperative findings with the goal of obtaining good functional results. Consequently, small areas of tumor were left untouched if

they were seen to invade the cavernous sinus or adhere severely to critical neurovascular structures (maximum possible resection with minimum neurological disability).

postoperative radiotherapyIn most cases, the patients were followed up without

additional treatment. SRS was performed in cases of re-current tumor or regrowth of residual tumor detected on MRI; 17 patients were treated with SRS.

Neuroradiological evaluationPreoperative and postoperative neuroimaging stud-

ies included 3D contrast-enhanced MRI to measure tu-mor volume. Postoperative MRI was performed within 3 months after surgery. In each axial MR image, tumor was demarcated by 2 radiologists and volumetric analysis was performed by 2 neurosurgeons. Volumetric analysis should ideally be calculated with computer-based meth-ods, but the MR images obtained in our early group of cases were saved as printed files, so tumor volume was cal-culated based on the sum of the values obtained through manual measurement on each individual slice.

Extent of resection (EOR) was calculated as follows: EOR(%) = (preoperative tumor volume − postoperative tumor volume)/preoperative tumor volume × 100.

Disabilities and performance To define functional outcomes, clinical follow-up was

conducted by the operating or referring surgeon. When a follow-up examination was not possible, a telephone in-terview was conducted with the patient or a close family member. (These interviews were conducted by the au-thors.) A new scoring system, the PCMIS (Table 1), was created for quantitative assessment of patient status and was used preoperatively, at 3 months after surgery, and at the time of the last follow-up examination. The PCMIS ad-dresses 8 categories of neurological functions and condi-tions associated with adverse effects of petroclival menin-giomas and their surgical treatment. Scores are assigned in each category according to the level of disability and its impact on the patient’s quality of life as determined on the basis of patient responses to questionnaires and the opin-ions of the neurosurgeons who provided treatment, with a maximum score indicating the most severe impairment in all functions. The House-Brackmann grading system13 is used to assess facial palsy and the Gardner-Robertson scale9 is used to assess hearing.

local controlRecurrence or regrowth of the tumor was diagnosed

if progression was observed on neuroimaging. When the tumor remained smaller than before surgery but caused symptoms or when the tumor became larger than preop-erative size, it was defined as not controlled. The results of tumor control were thus classified into 2 categories: con-trolled and not controlled.

statistical analysisData were analyzed using the Mann-Whitney U-test for

unpaired samples or Wilcoxon t-test for paired samples.

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combined transpetrosal approach for petroclival meningioma


Differences correlating to an error probability of less than 0.05 were considered statistically significant. Recurrence-free survival time and the cumulative risk of tumor re-currence were calculated according to the Kaplan-Meier method using JMP 9.0 software (SAS Institute Inc.).

resultstumor characteristics

In the 24 cases in the early group (1990–1999), the mean preoperative tumor volume was 31.3 cm3 (range 1.7–99.0 cm3). The mean postoperative tumor volume was 2.3 cm3 (range 0.0–32.3 cm3). The mean EOR was 96.1% (range 61.6%–100%) (Table 2).

In the 36 cases in the late group (2000–2009), the mean preoperative tumor volume was 32.1 cm3 (range 3.0–102.6 cm3). The mean postoperative tumor volume was 3.6 cm3 (range 0.0–53.4 cm3). The mean EOR was 92.7% (range 48.0%–100%) (Table 2).

Follow-up and survivalIn the early group (1990–1999), the mean follow-up

period was 12 years and 5 months (range 0–231 months). One of patients died because of postoperative intracranial hemorrhage due to severe venous infarction in the periop-erative period; excluding that patient, the mean duration of follow-up was 13 years (range 98–231 months). In the late group (2000–2009), the mean follow-up period was 6 years and 6 months (range 7–157 months). There was no death associated with the operation in the late group. There was no significant difference in recurrence-free survival (calculated using the Kaplan-Meier method) be-tween the early and late groups (Fig. 1).

local controlIn 3 cases, local control was not achieved with maxi-

mum feasible resection alone or in combination with SRS. In these 3 cases, the mean preoperative tumor volume was 75.2 ± 32.8 cm3, the mean postoperative tumor volume was 31.5 ± 22.3 cm3, the mean EOR was 62.3% ± 14.7%, and the mean MIB-1 labeling index was 2.3 ± 2.5. In 56 cases, good local tumor control was achieved. In this lat-ter group, the mean preoperative tumor volume was 30.0 ± 20.0 cm3, the mean postoperative tumor volume was 1.6 ± 2.5 cm3, the mean EOR was 95.7% ± 5.1%, and the mean MIB-1 labeling index was 2.6 ± 3.5. In the group without

table 1. petroclival meningioma impairment scale (pcMis)*

Category Description Score

A. Diplopia Visible malposition of eye 3Consistent diplopia 2Diplopia when looking in a single

direction 1

No impairment 0B. Facial sensation Severe pain, refractory to medication 3

Pain controllable w/ medication 2Numbness 1No impairment 0

C. Facial palsy House-Brackmann Grade IV–VI 3House-Brackmann Grade III 2House-Brackmann Grade II 1House-Brackmann Grade I 0

D. Hearing Gardner-Robertson Grade III–V 1Gardner-Robertson Grade I or II 0

E. Swallowing & speaking

Complete swallowing impairment treated w/ a feeding tube

5

Effortful swallowing & presence of hoarseness

2

Effortful swallowing or presence of hoarseness

1

No impairment 0F. Motor disturbance Restricted to bed & requires complete

assistance10

Restricted to wheelchair w/ some assistance

7

Gait disturbance requiring supportive devices such as cane & brace

5

Gait disturbance w/o supportive devices

2

No impairment 0G. Sensory distur-

banceSevere pain, refractory to medication 3

Pain controllable w/ medication 2Numbness 1No impairment 0

H. Consciousness & communication

Complete loss of communication ability

10

Some support in basic communication 7Independent in basic communication

but dependent in social communi-cation

5

Independent in daily & social com-munication but unable to function in previous employment

3

Suitable for previous level of employ-ment

0

Total ____* The maximum score, indicating the most severe impairment in all measures, is 38.

table 2. tumor characteristics and surgical results in the early (1990–1999) and late (2000–2009) groups

Characteristic or Results Early Group Late Group

No. of cases 24 36Mean age of patients (yrs) 53.7 54.9Mean preop tumor vol (cm3) 31.3 32.1Mean postop tumor vol (cm3) 2.3 3.6Mean EOR (%) 96.1 92.7Mean MIB-1 labeling index 2.88 2.51Mean duration of follow-up (mos) 149.3 77.9SRS (no. of cases) 3 14Local control (% of cases) 91.7 94.4

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local control, the pre- and postoperative tumor volumes were larger and the EOR was lower than in the group in which local control was achieved. A significant relation-ship was seen between pre- and postoperative tumor vol-ume and EOR (p < 0.05, Mann-Whitney U-test), but there was no significant relationship between failure to achieve local control and the MIB-1 labeling index (p < 0.05, Mann-Whitney U-test) (Table 3). There was a marked sig-nificant difference in recurrence-free survival (calculated using the Kaplan-Meier method) between patients with less than 85% EOR and patients in whom at least 85% tumor resection was achieved (Fig. 2).

long-term Disabilities and performanceThe PCMIS score was measured for all of the patients

preoperatively, at 3 months after surgery, and at the time of the last follow-up examination. The most common PCMIS disability categories for which scores worsened postoperatively were facial nerve palsy (Category C), dip-lopia caused by CN III, IV, and/or VI palsy (Category A), and hearing loss (Category D). All of these categories were scored on a scale of 0–3, with 3 indicating maxi-mum impairment.

In the early group, the postoperative total PCMIS score improved in 3 patients (12.5%), remained stable in 1 (4.2%), and worsened in 20 (83.3%), and the mean total preoperative, postoperative, and last follow-up scores were 3.8, 8.0, and 7.1, respectively. The total PCMIS scores after surgery tended to be higher than the preoperative values, indicating increased disability, with the scores not return-ing to preoperative levels at the time of long-term follow-up. For facial nerve palsy, present in 16 patients (67%), the mean preoperative, postoperative, and last follow-up PCMIS scores were 0.2, 2.0, and 1.5, respectively. For dip-lopia, present in 14 patients (58%), the scores were 0.7, 1.9, and 1.0, respectively, and for hearing loss, present in 10 pa-tients (42%), the mean preoperative, postoperative, and last follow-up scores were 0.3, 0.7 and 0.7, respectively (Fig. 3).

In the late group, the total PCMIS score improved post-

operatively in 23 patients (63.9%), remained stable in 5 (13.9%), and worsened in 8 (22.2%), and the mean pre-operative, postoperative, and last follow-up scores were 4.8, 4.1, and 2.8, respectively. The total PCMIS score showed an improvement postoperatively with respect to the preoperative level score, and the score at the time of the most recent long-term follow-up evaluation tended to be significantly better than the postoperative score (p < 0.05, Wilcoxon t-test). As in the early group, the most common category that demonstrated worsening postop-eratively was diplopia, which was present in 16 patients (44.4%), but in the late group the mean score for the most recent long-term follow-up evaluation was very close to the preoperative score. The mean preoperative, postopera-tive, and last follow-up scores for diplopia were 0.5, 1.2, and 0.6, respectively. The second most common disability postoperatively was facial nerve palsy, which was pres-ent in 11 patients (30.6%), but the PCMIS scores for this group recovered to preoperative levels at the time of the most recent long-term follow-up evaluation (mean preop-erative, postoperative, and last follow-up scores of 0.4, 0.8, and 0.4, respectively). The next most common disability was hearing loss, which was present in 9 patients postop-eratively (25%), and the mean preoperative, postoperative, and last follow-up scores were 0.2, 0.4, and 0.4, respec-tively. In 1 of these patients, the labyrinth was drilled out to widen the surgical corridor.

In 2 other PCMIS categories, facial sensation (Cate go-ry B) and motor disturbance (Category F), the scores for the late group showed significant improvement, with the mean postoperative scores in the late group being 0.3 and 0.6 compared with the mean preoperative scores of 0.8 and 1.5 (with scores of 3 and 10 indicating maximum dis-ability) for facial sensation and motor disturbance, respec-tively (p < 0.05, Wilcoxon t-test) (Fig. 3).

In both groups, there was a tendency for the PCMIS scores for diplopia and facial palsy to be worse immedi-ately after surgery than preoperatively and recover at the final follow-up evaluation. On the other hand, there was a tendency for the PCMIS score for hearing to be worse after surgery than preoperatively and not recover. In the late group, the total PCMIS score tended to be better than in the early group at the time of postoperative and recent follow-up evaluation (Fig. 3).

DiscussionPetroclival meningiomas are among the most difficult

tumors of the skull base, with respect to surgical treat-

table 3. relationship between extent of tumor removal and local control in 59 cases*

VariableLocal Control

(n = 56)Local Recurrence

(n = 3)

Preop tumor vol (cm3) 30.0 ± 20.0 75.2 ± 32.8†Postop tumor vol (cm3) 1.6 ± 2.5 31.5 ± 22.3†EOR (%) 95.7 ± 5.1 62.3 ± 14.7†MIB-1 labeling index (%) 2.6 ± 3.5 2.3 ± 2.5

* Values are mean ± SD.† Statistically significant (p < 0.05, Mann-Whitney U-test).

FiG. 1. Kaplan-Meier curves for recurrence-free survival showing no significant difference between the early and late groups. Follow-up time (in months) for the operative periods is shown on the x-axis and recurrence-free survival rates are shown on the y-axis.

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ment, and many reports have demonstrated marked evolu-tion in the microsurgical management of these lesions.1–8,

12,17,21,23–25,29,30,32 However, complete resection is sometimes not possible, and SRS for newly diagnosed, incompletely resected, or recurrent tumors has gained increasing accep-tance over the past decade.3,8,16,17,19,20,24–26,33,35 Because the optimal treatment protocol remains controversial, analyses are needed to establish the indications for surgery and sur-gical goals that maximize benefit for the patient. Quantita-tive evaluations with objective measurement of tumor vol-ume and the patient’s condition are necessary to compare outcomes of various treatments in various institutions. This study was undertaken to meet some of these needs.

Quantitative evaluation and petroclival MeningiomaIn patients with petroclival meningioma, assessment of

treatment based on the number of new postoperative neu-rological deficits may be misleading. For example, some neurological symptoms that severely affect patients’ per-formance status, such as hemiparesis or ataxia, may be dramatically improved after surgery, but other symptoms, such as diplopia, facial nerve palsy, and hearing ability, are sometimes worsened. Therefore, a comprehensive method of measure patients’ status is needed. The Karnofsky Per-formance Status (KPS) has been the gold standard over the years for comprehensive assessment of a patient’s con-dition. However, it is not readily applicable to patients with petroclival meningiomas due to the rough classification of each score. A patient suffering hearing disturbance before surgery may have a KPS score of 80, and if he or she ad-ditionally suffers facial palsy after surgery, the KPS score will still be 80 postoperatively. In fact, almost all the pa-tients in our case series had a KPS score of 70 or more before and after surgery; 58 (96.7%) of 60 patients had a preoperative KPS score of 70 or more, and 56 (94.9%) of 59 patients had a KPS score of 70 or more postopera-tively. Moreover, in 42 (70%) of 60 cases, the difference in KPS scores before and after surgery was within 10 points. Comparison of PCMIS and KPS scores in our early group showed that the PCMIS improved in 3 patients (12.5%), remained stable in 1 (4.2%), and worsened in 20 (83.3%), whereas the KPS score improved in 7 patients (29.2%), remained stable in 7 (29.2%), and worsened in 10 (41.6%). In the late group, the PCMIS improved in 23 patients (63.9%), remained stable in 5 (13.9%), and worsened in 8 (22.2%), whereas the KPS score improved in 21 patients (58.3%), remained stable in 10 (27.8%), and worsened in 5 (13.9%). Evaluation on the basis of KPS scores tends to underestimate postoperative complications in patients with petroclival meningioma. In these patients, disability

FiG. 2. Kaplan-Meier curves for recurrence-free survival showing comparison of patients with EOR ≥ 85% versus patients with EOR < 85% (p < 0.001). Follow-up time (in months) for the operative periods is shown on the x-axis and recurrence-free survival rates are shown on the y-axis.

FiG. 3. Average preoperative, postoperative, and recent follow-up PCMIS scores for the early and late groups. The scores for diplopia and facial palsy tended to be worse immediately after surgery than preoperatively but recovered at the final follow-up evaluation. The scores for hearing ability tended to be worse after surgery than preoperatively, but did not show the same recovery as the scores for diplopia and facial palsy. The total PCMIS score tended to be better in the late group than in the early group at the time of postoperative and recent follow-up evaluation.

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assessment using the KPS may not be precisely quanti-fiable. Moreover, the KPS is not comprehensive enough to indicate subtle neurological changes during the course of illness. For these reasons, we formulated a new scor-ing system, the petroclival meningioma impairment scale (PCMIS), based on a comprehensive neurological exami-nation specific to petroclival lesions. In this scoring sys-tem, higher points are assigned to neurological symptoms that severely affect the patient’s quality of life, such as impairment of swallowing and speaking, motor function, or consciousness and communication. The weight of each score was decided based on the questionnaire regarding neurological deficits that severely affect the daily activity. Today, maximum possible resection with functional pres-ervation is regarded as the optimal surgery for petroclival meningiomas, and we believe the PCMIS is more appro-priate than the KPS for assessing results for these patients.

To evaluate resection of petroclival meningiomas, the degree of surgical removal has been classified into gross-total, subtotal, or partial in many previous reports.23,24,31 However, considering the recent trend of maximum pos-sible resection with functional preservation, most petro-clival meningiomas were subtotally resected, leaving be-hind some tumor residue around critical neurovascular structures. Therefore, the extent of tumor excision cannot be estimated by this classification (gross-total, subtotal, or partial resection). Thus, we calculated tumor volume and quantitative extent of resection (EOR) to evaluate the ex-tent of tumor removal.

These evaluations in this study should be particularly useful in comparison of treatments such as primary SRS or partial resection followed by SRS.

comparison of surgical results from 2000–2009 versus 1990–1999

To evaluate improvements in techniques with the accru-al of cases, patients were classified into 2 groups according to the operative period. In the early group (1990–1999), a high EOR (96.1%) led to a high tumor control rate (91.7%), but the patients’ PCMIS scores worsened after surgery. On the other hand, in the late group (2000–2009), a high EOR (92.7%) led to a high tumor control rate (94.4%), and the PCMIS scores improved after surgery. No significant dif-ference in EOR was identified between these 2 groups, but the mean postoperative PCMIS score was markedly and significantly more satisfactory in the late group than in the early group (p < 0.05, Mann-Whitney U-test). This means that our results from the late group were clearly not attrib-utable to a low resection rate.

The reasons for good results in the late group should be considered as follows: intentional tumor residue in criti-cal regions such as the cavernous sinus or where tumor is severely adherent to critical neurovascular structure (maximal possible resection), in consideration of the effec-tiveness of SRS; prevention of venous infarction by pres-ervation of basal venous drainage routes; and technical ad-vances in intraoperative monitoring of intracranial nerves or neuronavigation systems. Although improvements in such techniques cannot be evaluated by statistical analy-sis, our results suggest that the cumulative minor changes in surgical technique and the increase in experience have

markedly improved the safety of skull base surgery. So, we suggest that modern skull base surgery is not as dangerous as described in past reports.15

effects of using a combined transpetrosal approach for petroclival Meningiomas

The indications for a transpetrosal approach for petro-clival meningiomas are sometimes controversial. Transpe-trosal approaches are usually advantageous for minimiz-ing temporal lobe retraction, thereby allowing access to the anterior brainstem and clivus and permitting removal of clival tumors. These approaches are, however, labori-ous, and they entail intricate dissection of intra- and extra-dural parts of the auditory and nerve complexes.

There was no mortality in this series of 36 consecutive patients who were operated on via combined transpetro-sal approach in late group (2000–2009). Serious surgical complication (PCMIS score increase ≥ 15 points) occurred in 1 (2.8%) of 36 patients; this patient had a refractory sei-zures (status epilepticus) in the perioperative period and required institutional or hospital care. Two patients with aggressive tumors experienced progressive tumor growth.

Al-Mefty et al.2 reported a retrospective analysis of 64 cases of petroclival meningiomas involving patients who were surgically treated between 1988 and 2012 with the goal of total tumor resection. On follow-up, the average KPS score was 88.28 (median 90). Resection resulted in improved KPS scores in 30 patients (47%), while 23 pa-tients (36%) had equivalent pre- and postoperative KPS scores. In 11 cases (17%), the KPS scores decreased after surgery. We also reanalyzed functional outcome by KPS and found that, in the late group, the KPS score improved on follow-up in 21 patients (58.3%), remained stable in 10 (27.8%), and worsened in 5 (13.9%). Useful hearing was preserved in 23 (79.3%) of 29 patients who were treated surgically with an attempt at hearing preservation, and good facial nerve function (House-Brackmann Grade I or II) was obtained in 32 (86.1%) of 36 patients at the time of the long-term follow-up. The morbidity of the patients in the late group was similar to or slightly more favorable than in other recent series that used hearing-preserving ap-proaches for petroclival meningiomas; in other series, the rates of serious morbidity and mortality have ranged from 6% to 40%.4,7,10,17,18,21,22,27 Outcomes related to CN VII and VIII were clearly better in this series than those reported from series with non–hearing-preserving approaches, in which hearing was always lost and only 55% of the pa-tients had House-Brackmann Grade I or II facial nerve function at follow-up examination.11,14,28

Optimal treatment for petroclival MeningiomasThe surgical management of medium-sized or large

petroclival meningiomas has frustrated neurosurgeons for many years. In this study, we evaluated tumor volume quantitatively and showed the relationship between EOR and local tumor control. In the cases in which local control was not achieved, postoperative tumor volume was larger and EOR was lower than with the cases in which local control was achieved. These results draw attention to the favorable effect of maximizing the resection rate on long-term tumor control.

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Of course, a high EOR leads to a high tumor control rate. However, the high morbidity rate in our early group (1990–1999) indicates the high surgical risks associated with total excision of lesions, as previous authors of re-ports have mentioned.4,7,17,31 Observation, SRS, and a com-bination of partial resection and SRS are also alternatives to radical resection.

Regarding the natural history of these tumors, a study by Van Havenbergh et al.34 presented a retrospective series of 21 cases involving patients with untreated petroclival meningioma who underwent regular clinical and radio-logical follow-up evaluations. During the follow-up moni-toring, tumor growth was observed on imaging studies in 76% of the cases, and in 63% of these cases, the patients’ function deteriorated. These data demonstrate that petro-clival meningiomas grow slowly, but that in cases in which they do grow, the long-term outcomes tend to be poor. In our study, patients with large petroclival meningiomas had a greater increase in PCMIS score (reflecting greater de-cline in function) than patients with medium-sized tumors.

Radiosurgery has shown promise for control of small petroclival meningiomas.16,26,33 However, radiosurgery is suitable only for small lesions in this location. Unfortu-nately, most tumors are diagnosed when they are already too large for radiosurgery, and the risk of delayed adverse effects on the brainstem, including transient cranial neu-ropathies, must be taken into account.33 Flannery et al.8 reported that a significant risk factor for tumor progression was a tumor volume ≥ 8 cm3 in their study on the long-term control of petroclival meningiomas through radiosurgery.

Many neurosurgeons have preferred treatments such as the combination of partial resection and additional SRS.17,24 Such treatments have shown acceptable outcomes for fairly long follow-up periods, but the degree of tumor reduction at initial surgery has not been mentioned. In this study, patients with less tumor removal (EOR < 85%) had significantly shorter recurrence-free survival (calculated using the Kaplan-Meier method) than those who had radi-cal tumor excision (EOR ≥ 85%). Safe radical resection for preserving high quality of life is optimal for patients. Our results in the late group (2000–2009) demonstrate the degree of safety with which radical resection of medium-sized or large petroclival meningiomas can be achieved. The mean EOR in this group was 92.7%, and this was achieved with a mortality rate of 0% and a severe morbid-ity rate of 2.2%. The local control rate was 94.4%, and the percentages of patients with an improved or unchanged PCMIS score were 63.9% and 13.9%, respectively, sup-porting the relative safety of our treatments. The modern combined transpetrosal approach has provided satisfac-tory functional improvements for patients with medium-sized or large petroclival meningiomas. Although we have resected tumors via a combined transpetrosal approach, if the same EOR and the improvement of PCMIS score are achieved, other surgical procedures combined with SRS will result in similar outcomes.

We believe maximal resection via a combined trans-petrosal approach is the best treatment for medium-sized or large petroclival meningiomas. Adjuvant treatment, es-pecially SRS, can be considered after resection when re-current tumor or growth of residual tumor is detected on MRI. SRS may also be the preferred primary treatment for

asymptomatic patients with small tumors. However, more aggressive treatment is recommended for young patients or patients with short symptom duration.

conclusionsThe present study showed the role of quantitative evalu-

ations for petroclival meningiomas and investigated the surgical results of petroclival meningiomas resected via combined transpetrosal approach. Maximal resection fol-lowed by SRS when necessary can provide effective con-trol of these tumors. The PCMIS is a useful scoring scale to comprehensively measure patient’s status with petro-clival meningiomas.

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author contributionsConception and design: Morisako, Goto. Acquisition of data: Morisako, Goto. Analysis and interpretation of data: Morisako, Goto. Drafting the article: Morisako, Goto. Critically revising the article: Morisako, Goto. Reviewed submitted version of manu-script: all authors. Approved the final version of the manuscript on behalf of all authors: Morisako. Statistical analysis: Morisako. Administrative/technical/material support: all authors. Study supervision: Goto, Ohata.

correspondenceHiroki Morisako, Department of Neurosurgery, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka 545-8585, Japan. email: [email protected].

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Petroclival meningiomas resected via a combined ... · tactic radiosurgery (SRS) for newly diagnosed, incom-pletely resected, or recurrent tumor has gained increasing Petroclival