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Yoshihisa Kida, Masayuki Yoshimoto and Toshinori Hasegawa

Object

The aim of this study was to evaluate the results of radiosurgery in patients with facial schwannoma.

Methods

The study population consisted of 14 patients, six men and eight women, with a mean age of 45.4 years. Most of the patients had presented with facial palsy (11 of 14 patients) and/or hearing disturbance (nine of 14 patients). Prior treatment in nine of the 14 cases consisted of tumor resection or tumor biopsy. Tumor volume ranged from 0.98 to 20.8 cm3, and the mean tumor volume was 5.5 cm3. The mean maximum radiation dose and mean tumor margin dose used for radiosurgery were 24.0 and 12.9 Gy, respectively.

During the mean follow-up period of 31.4 months (range 12–120 months), 10 of the tumors shrank and four remained unchanged. The tumor response and tumor control rates were 57 and 100%, respectively. None of the tumors progressed, and no subsequent resection was required. Facial nerve function improved in five cases, remained unchanged in eight, and became worse in one. There was no change in hearing function in any of the patients. Complications developed in only one patient: the onset of facial palsy immediately after treatment, which subsequently recovered to House–Brackmann Grade III.

Conclusions

In summary, radiosurgery was found to be a very useful method of treating facial schwannoma, for both tumor control and functional control. Radiosurgery should therefore be the treatment of first choice for facial schwannomas.

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Tatsuya Kobayashi, Yoshihisa Kida and Toshinori Hasegawa

Object

One hundred seven cases of craniopharyngiomas were treated using gamma knife surgery (GKS) at Komaki City Hospital during the past 12 years. The authors report the long-term results obtained in 100 patients who were followed for 6 to 148 months (mean 65.5 months).

Methods

All patients underwent GKS. The mean tumor diameter and volume were 18.8 mm and 5.8 ml, respectively; lesions were treated with a maximum dose of 21.8 Gy and marginal dose of 11.5 Gy (mean isocenters 4.5). Overall tumor responses were complete in 19, partial in 44, no change in 14, and disease progression in 23, yielding a complete response rate of 19%, overall response rate of 63%, control rate of 77%, and progression rate of 23%. Considering factors such as patient age, nature of the tumor (solid, mixed, cystic), frequency of previous treatments, and tumor size, the age and nature of the tumor were significant prognostic factors.

Changes in neurological and pituitary–hypothalamic symptoms after GKS were evaluated in 91 patients. Overall improvement was demonstrated in 17 (18.7%), no change in 59 (64.8%), and deterioration in 15 (16.5%). Outcome was documented in 93 cases: excellent in 42, good in 23, fair in seven, poor in three, and dead in 18 patients.

Conclusions

Stereotactic GKS is a safe and effective treatment as an adjuvant or boost therapy for postresection residual and/or recurrent craniopharyngiomas; the effects are durable and side effects acceptable.

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Jacques J. Morcos

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Toshinori Hasegawa, Yoshihisa Kida, Masayuki Yoshimoto and Jouji Koike

Object

Information on outcomes of Gamma Knife surgery (GKS) for patients harboring trigeminal schwannomas is limited because these tumors are rare. The authors evaluated tumor control and functional outcomes in patients who underwent GKS for trigeminal schwannomas to clarify the efficacy of this treatment.

Methods

Forty-two patients with trigeminal schwannomas but no evidence of neurofibromatosis Type 2 were treated with GKS at Komaki City Hospital between November 1991 and December 2003. Of these, 37 patients were assessed. The mean tumor volume in these patients was 10 cm3. The mean maximum radiation dose directed to the tumor was 27.9 Gy and the mean dose directed to the tumor margin was 14.2 Gy. The mean follow-up period was 54 months. In four patients (11%) there was complete tumor remission; in 20 (54%) there was partial tumor remission; in eight (22%) the disease remained stable; and in five (14%) the tumor enlarged or uncontrollable facial pain developed with radiation-induced edema requiring resection. The actuarial 5- and 10-year tumor control rates were both 84%. With respect to functional outcomes, 40% of patients noted an improvement in their symptoms, and one patient experienced new symptoms despite good tumor control.

Conclusions

Gamma Knife surgery was a safe and effective treatment for a select group of patients harboring trigeminal schwannomas. Large tumors that compress the brainstem and cause deviation of the fourth ventricle should first be removed surgically and any remnant should be treated by GKS.

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Toshinori Hasegawa, Yoshihisa Kida, Takenori Kato, Hiroshi Iizuka and Takashi Yamamoto

Object

Gamma Knife surgery (GKS) has been a safe and effective treatment for small- to medium-sized vestibular schwannomas (VSs) over relatively long-term outcomes. However, even with recent radiosurgical techniques, hearing results following GKS remain unsatisfactory. The purpose of this study was to evaluate the hearing preservation rate as well as factors related to hearing preservation in patients with VSs and serviceable hearing who were treated with GKS.

Methods

Among patients with Gardner-Robertson (GR) Class I or II serviceable hearing and VSs treated with GKS between 1991 and 2009, 117 were evaluable via periodic MR imaging and audiometry.

Results

The median age at the time of GKS was 52 years. Four patients (3%) had undergone prior surgery. Fifty-six patients (48%) had GR Class I hearing and 61 (52%) had GR Class II hearing at the time of GKS. The median tumor volume was 1.9 cm3. The median maximum and tumor margin radiation doses were 24 and 12 Gy, respectively. The median follow-up periods for MR imaging and audiometry were 74 and 38 months, respectively. The overall tumor control rate was 97.5%. Actuarial 3-, 5-, and 8-year hearing preservation rates were 55%, 43%, and 34%, respectively. On multivariate analysis, GR hearing class at the time of GKS and the mean cochlear dose affected hearing preservation significantly. In a limited number of patients who were treated using the most recent dose planning techniques and who had GR Class I hearing before treatment, the 3- and 5-year hearing preservation rates increased to 80% and 70%, respectively.

Conclusions

For the majority of patients with small- to medium-sized VSs, GKS was an effective and reasonable alternative to resection with satisfactory long-term tumor control. Factors related to hearing preservation included a GR Class I hearing pre-GKS and a lower mean cochlear radiation dose. To retain serviceable hearing, it is important to apply GKS treatment while patients retain GR Class I hearing.

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Toshinori Hasegawa, Yoshihisa Kida, Takenori Kato, Hiroshi Iizuka, Shunichiro Kuramitsu and Takashi Yamamoto

Object

Little is known about long-term outcomes, including tumor control and adverse radiation effects, in patients harboring vestibular schwannomas (VSs) treated with stereotactic radiosurgery > 10 years previously. The aim of this study was to confirm whether Gamma Knife surgery (GKS) for VSs continues to be safe and effective > 10 years after treatment.

Methods

A total of 440 patients with VS (including neurofibromatosis Type 2) treated with GKS between May 1991 and December 2000 were evaluable. Of these, 347 patients (79%) underwent GKS as an initial treatment and 93 (21%) had undergone prior resection. Three hundred fifty-eight patients (81%) had a solid tumor and 82 (19%) had a cystic tumor. The median tumor volume was 2.8 cm3 and the median marginal dose was 12.8 Gy.

Results

The median follow-up period was 12.5 years. The actuarial 5- and ≥ 10-year progression-free survival was 93% and 92%, respectively. No patient developed treatment failure > 10 years after treatment. According to multivariate analysis, significant factors related to worse progression-free survival included brainstem compression with a deviation of the fourth ventricle (p < 0.0001), marginal dose ≤ 13 Gy (p = 0.01), prior treatment (p = 0.02), and female sex (p = 0.02). Of 287 patients treated at a recent optimum dose of ≤ 13 Gy, 3 (1%) developed facial palsy, including 2 with transient palsy and 1 with persistent palsy after a second GKS, and 3 (1%) developed facial numbness, including 2 with transient and 1 with persistent facial numbness. The actuarial 10-year facial nerve preservation rate was 97% in the high marginal dose group (> 13 Gy) and 100% in the low marginal dose group (≤ 13 Gy). Ten patients (2.3%) developed delayed cyst formation. One patient alone developed malignant transformation, indicating an incidence of 0.3%.

Conclusions

In this study GKS was a safe and effective treatment for the majority of patients followed > 10 years after treatment. Special attention should be paid to cyst formation and malignant transformation as late adverse radiation effects, although they appeared to be rare. However, it is necessary to collect further long-term follow-up data before making conclusions about the long-term safety and efficacy of GKS, especially for young patients with VSs.

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Toshinori Hasegawa, Yoshihisa Kida, Masayuki Yoshimoto, Hiroshi Iizuka, Dai Ishii and Kouta Yoshida

Object

The aim of this study was to evaluate the outcomes in patients with convexity, parasagittal, or falcine meningiomas treated using Gamma Knife surgery (GKS) and to determine management strategy considering a risk of radiation-induced edema.

Methods

One hundred twelve patients who harbored 125 convexity, parasagittal, or falcine meningiomas were assessed. Forty-six patients underwent GKS as the initial treatment. The median tumor diameter was 25 mm, and median tumor volume was 8 cm3. The median maximum and margin doses were 30 and 16 Gy, respectively.

Results

The median follow-up period was 72 months. The actuarial 5- and 10-year progression-free survival rates were 78% and 55%, respectively. The actuarial 5- and 10-year local tumor control rates were 87% and 71%, respectively. Of 29 tumors that developed postradiosurgical edema, 7 were symptomatic. The actuarial symptomatic radiation-induced edema rate was 7%. The incidence of this complication was significantly higher in patients who underwent GKS as the initial treatment. Six of 46 patients for whom GKS was the initial treatment had preradiosurgical edema. Of these 6 patients, 4 developed severe panhemispheric edema after GKS (2 patients with parasagittal tumors, 1 with a falx tumor, and 1 with a convexity tumor).

Conclusions

Gamma Knife surgery is an effective treatment for convexity, parasagittal, and falcine meningiomas as the initial or adjuvant treatment. However, GKS should be restricted to small- to medium-sized tumors, particularly in patients with primary tumors, because radiation-induced edema is more common in convexity, parasagittal, and falcine meningiomas than skull base meningiomas.

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Toshinori Hasegawa, Yoshihisa Kida, Masayuki Yoshimoto, Joji Koike, Hiroshi Iizuka and Dai Ishii

Object

The aim of this study was to evaluate long-term outcomes, including tumor control and neurological function, in patients with cavernous sinus meningiomas treated using Gamma Knife surgery (GKS).

Methods

One hundred fifteen patients with cavernous sinus meningiomas, excluding atypical or malignant meningiomas, were treated with GKS between 1991 and 2003. Forty-nine patients (43%) underwent GKS as the initial treatment. The mean tumor volume was 14 cm3, and the mean maximum and margin doses applied to the tumor were 27 and 13 Gy, respectively. The median follow-up period was 62 months. During the follow-up, 111 patients were able to be evaluated with neuroimaging.

Results

The actuarial 5- and 10-year progression-free survival rates were 87 and 73%, respectively. Similarly, the actuarial 5- and 10-year focal tumor control rates were 94 and 92%, respectively. Regarding functional outcomes, 43 patients (46%) experienced some degree of improvement, 40 (43%) remained stable, and 11 (12%) had worse preexisting or newly developed symptoms. Patients who underwent GKS as the initial treatment experienced significant improvement of their symptoms (p = 0.006).

Conclusions

Gamma Knife surgery is a safe and effective treatment over the long term in selected patients with cavernous sinus meningiomas. Tumor progression is more likely to occur from the lesion margin outside the treatment volume. In small to medium-sized tumors, GKS is an excellent alternative to resection, preserving good neurological function. For relatively large-sized tumors, low-dose radiosurgery (≤ 12 Gy) is acceptable for the prevention of tumor progression.

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Toshinori Hasegawa, Dai Ishii, Yoshihisa Kida, Masayuki Yoshimoto, Joji Koike and Hiroshi Iizuka

Object

The purpose of this study was to evaluate radiosurgical outcomes in skull base chordomas and chondrosarcomas, and to determine which tumors are appropriate for stereotactic radiosurgery as adjuvant therapy following maximum tumor resection.

Methods

Thirty-seven patients (48 lesions) were treated using Gamma Knife surgery (GKS); 27 had chordomas, seven had chondrosarcomas, and three had radiologically diagnosed chordomas. The mean tumor volume was 20 ml, and the mean maximum and marginal doses were 28 and 14 Gy, respectively. The mean follow-up period was 97 months from diagnosis and 59 months from GKS.

Results

The actuarial 5- and 10-year survival rates after GKS were 80 and 53%, respectively. The actuarial 5- and 10-year local tumor control (LTC) rates after single or multiple GKS sessions were 76 and 67%, respectively. All patients with low-grade chondrosarcomas achieved good LTC. A tumor volume of less than 20 ml significantly affected the high rate of LTC (p = 0.0182). No patient had adverse radiation effects, other than one in whom facial numbness worsened despite successful tumor control.

Conclusions

As an adjuvant treatment after resection, GKS is a reasonable option for selected patients harboring skull base chordomas or chondrosarcomas with a residual tumor volume of less than 20 ml. Dose planning with a generous treatment volume to avoid marginal treatment failure should be made at a marginal dose of at least 15 Gy to achieve long-term tumor control.