Volume reduction in meningiomas after gamma knife surgery

[Base of the skull meningioma: Efficacy, clinical tolerance and radiological evaluation after radiotherapy]

Skull base meningioma leads to functional disturbances, which can significantly alter the quality of life. The optimal management of these lesions, whose goals are neurological preservation and tumour local control, is not yet clearly established. It is widely recognized that the goal of a radical excision should be abandoned despite the advances in the field of microsurgery of skull base lesions. Although less morbid, partial tumour excision would be associated with increased risk of local tumour recurrence. Although discussed both exclusive and adjuvant have proven to be highly successful in terms of clinical improvement and local control. Various radiation techniques have demonstrated their efficacy in the management of this pathology. However, high rates of clinical improvement are in contrast with low rates of radiological improvement. The notion of clinical and radiological dissociation appeared. However, in most of these studies, the analysis of the radiological response could be subject of legitimate criticism. This work proposes to review the local control, the efficacy and the clinical tolerance and the radiological response of the various radiation techniques for the meningioma of the base of the skull and to demonstrate the interest of quantitative volumetric analyses in the follow-up of meningioma after radiotherapy.

Analysis of the results of recurrent intracranial meningiomas treated with re-radiosurgery

OBJECTS

Meningioma is the most common intracranial neoplasm, comprising approximately 30% of all primary intracranial tumors (Claus et al., 2005) [1]. Treatment options include observation, microsurgical resection, stereotactic radiosurgery (SRS), and whole brain radiation therapy (WBRT). Gamma knife radiosurgery (GKRS) is a very effective treatment for intracranial meningiomas; previous studies showed the tumor control rate at 5-10 years of follow-up as 84.3%-100% in all cases (Feigl et al., 2005; Linskey et al., 2005; Malik et al., 2005; Aichholzer et al., 2000; Hakim et al., 1998; Chang and Adler 1997; Lunsford, 1994; Ganz et al., 1993) [2-9]. Many studies have discussed issues like optimal dose, conformal configurations, and adverse effects to improve the treatment result with GKRS (Malik et al., 2005; Kenai et al., 2005; Rowe et al., 2004; Shrieve et al., 2004) [4,10-12]. There are some cases in which the radiosurgery result is unfavorable and perhaps further treatment is needed. In these cases, re-radiosurgery can be an option. However, there have not been comprehensive studies discussing the issues of re-radiosurgery. Therefore, we analyzed the result of re-radiosurgery for recurrent meningiomas and their impact on clinical outcomes.

METHODS

From 1995 to 2015, we retrospectively reviewed 1163 patients who underwent GKRS for intracranial meningioma at the Asan Medical Center. Patients with multiple meningiomas or a follow-up with a period of less than a year were excluded from this study. Finally, 865 patients were enrolled in this study. Clinical symptoms and brain magnetic resonance imaging (MRI) scans were assessed by neurosurgeons. When tumor size increased together with newly developed neurologic symptoms, further management, such as microsurgical resection or SRS, was considered. Histologic analysis of the resected tumors was performed by neuropathologists. Clinical data, including patient's sex, age, and tumor locations were recorded. Treatment data included tumor volume, tumor grade, radiation dose, and presence of edema. Final outcome data including follow-up period, time to progression, interval between first and second radiosurgery courses and interval between microsurgery and radiosurgery were obtained.

RESULTS

Among 865 patients, tumor recurrence was found in 63 patients (7.28%). Seven patients showed transient tumor growth after GKRS. These patients have been under close observation without any further treatments. Fifty-six patients (6.47%) showed permanent tumor growth on follow-up MRI. Thirty-three patients from this group underwent repeated radiosurgery owing to tumor growth, resulting in a re-irradiation rate of 3.82% at our radiosurgery center. The other 23 patients were treated using methods other than re-radiosurgery. Among the 33 patients, 25 underwent microsurgical resection prior to their initial course of GKRS, and the other 8 were treated with re-radiosurgery only. An analysis was performed to determine factors that may have a role in treatment results. Of the many variables, tumor grade (p=0.004, Fisher's exact test) was the only significant factor for progression-free survival (PFS). Thirteen patients with unbiopsied or benign meningioma showed stable tumor size, while there was tumor growth in 8 patients. Among high-grade meningioma patients, 3 and 9 showed stable disease and tumor growth, respectively. As a result of re-radiosurgery, 11 out of 17 patients showed tumor growth and needed further treatments; this involved a third GKRS for 4 patients, microsurgical resection for 6 patients, and cyber knife radiosurgery (CKRS) for 1 patient. Four patients from this group were also treated with WBRT.

CONCLUSION

We analyzed the results of re-radiosurgery for recurrent meningiomas and observed that World Health Organization (WHO) grade II and III was significantly associated with a lower PFS rate compared with low-grade meningiomas (p=0.004). Conversely, patients with benign meningioma or unbiopsied tumors had much better results. Hence, re-radiosurgery is recommended for patients with unknown or benign meningiomas if their first GKRS result is unsatisfactory. However, re-radiosurgery should be considered carefully for recurrent high-grade tumors. Owing to the small number of recurrent meningioma patients treated with re-radiosurgery, further studies are required to delineate the role of this treatment.

Pediatric symptomatic Rathke cleft cyst compared with cystic craniopharyngioma

INTRODUCTION

Symptomatic Rathke cleft cysts (RCCs) are rarely detected in neuroradiological screening and are less commonly found in children than in adults. However, when RCCs are observed in children, it is important to carefully distinguish a RCC from a cystic craniopharyngioma (CP) even if surgically treated or conservatively followed up.

METHODS

We conducted a retrospective review of clinical data from 11 patients with symptomatic RCCs whose ages were under 18 years and compared the data with data from 15 age- and sex-matched patients with cystic CP who were treated at our institute.

RESULTS

The mean age of the patients with RCCs was 12.2 years (range, 6-18). There were six males and five females. As initial symptoms, nine patients presented with headache, while two each had impaired visual function, diabetes insipidus, and activity loss. The 14 patients with CP suffered from impaired visual function. Magnetic resonance imaging (MRI) mainly showed hyperintensity on T1-weighted images (WIs) and hypointensity on T2-WI in patients with RCC. However, patients with CP had characteristic hyperintensity on T2-WI. The average maximum diameter of the RCCs was 19.0 mm on average (range, 8-33 mm). The RCCs were thus significantly smaller than CPs (34.9 mm; range, 21-54 mm). The RCCs were usually oval or dumbbell-shaped and regular in appearance, while the larger CPs were lobular and irregular. A preoperative endocrinological evaluation revealed insufficiencies in four axes in five patients with RCC. Postoperative endocrinological status improved in three patients, remained unchanged in three, and worsened in one. The gonadotropin axis was damaged in a majority (nine) of the patients with CP preoperatively. Postoperative evaluation revealed deficits in five axes in 14 patients with CP, which is a significantly different trend than observed in patients with RCC. Eight patients underwent surgical procedures (transsphenoidal surgery (TSS) in four, craniotomy in four). Two of these patients experienced a recurrence of the cysts. One of these patients subsequently underwent two craniotomies followed by radiation and other underwent TSS. Among the three conservatively treated patients, two experienced a transient worsening of their symptoms along with cyst enlargement. However, none of the three conservatively treated patients required an operation.

CONCLUSIONS

When RCCs become symptomatic in children, the most common symptom they lead to is headache. The cysts are commonly small, regular, and oval in shape. Hypointensity of cyst contents on MRI is a characteristic of RCCs, which distinguishes them from CPs. Surgical intervention can be effective and lead to the relief of symptoms without a high rate of complications. However, there seems to be a relatively high recurrence rate following surgery. Thus, if the patient's symptoms remain minor, the surgical treatment option should be used only when prudent, as the patient's symptoms may improve over time.

Reliability of the Size Evaluation Method for Meningiomas: Maximum Diameter, ABC/2 Formula, and Planimetry Method

BACKGROUND

To evaluate the accuracy of tumor size by maximum diameter, ABC/2 formula, and planimetry method using thick-slice and thin-slice magnetic resonance imaging (MRI).

METHODS

Maximum diameter and tumor volume calculated using ABC/2 formula (V1) and planimetry method with thick-slice MRI (V2) and thin-slice MRI (V3) were examined in 83 meningiomas. Form factor (FF) analysis was performed to assess irregularity of the tumor. V3 values were considered as real tumor volumes. The accuracy of V1 and V2 was evaluated using ratio and difference from V3. Meningiomas were categorized by tumor locations: skull base (anterior, middle, and posterior) and non-skull base (calvaria and other sites).

RESULTS

Correlation between maximum diameter and V3 was statistically significant (r = 0.91), but the error was significant in tumors with longer maximum diameters. Correlation between V1 and V3 was significant (r = 0.97). However, V1 tended to be larger in middle skull base meningiomas or in tumors with low FF values (R² = 0.21). V2 represented relatively accurate volumes in both groups except in the case of small meningiomas. When tumors were demonstrated within 3 fractions on thick-slice MRI, the ratio of V2 to V3 showed significant variability.

CONCLUSIONS

Using the ABC/2 formula, the volume of meningiomas in the middle skull base or meningiomas with low FF value might be calculated larger than the real tumor volume. The planimetry method with thick-slice MRI demonstrated relatively accurate volumes if the tumor was fractionated in >4 slices.

Intraparenchymal infiltration of Rathke's cleft cysts manifesting as severe neurological deficits and hypopituitarism: 2 case reports

BACKGROUND

Rathke's cleft cysts generally remain asymptomatic throughout life, but a few patients may suffer severe neurological and/or endocrinological deficits. The symptoms include visual disturbances caused by compression of the optic chiasm, and severe endocrinological deficits caused by repeated intracystic hemorrhage or leakage of cyst content. However, no case of Rathke's cleft cyst has infiltrated into neuroglial tissue with marked cerebral edema.

CASE PRESENTATION

Two patients presented with non-infectious re-deterioration of Rathke's cleft cysts with intraparenchymal infiltration and marked cerebral edema, to ipsilateral hypothalamus in one case and to the bilateral frontal lobes in the other. Both patients were surgically treated by extended transsphenoidal surgery, and showed remarkable improvement with postoperative pulse-dose steroid therapy, including disappearance/shrinkage of abnormal enhanced lesion and cerebral edema on magnetic resonance imaging. Histological examination disclosed significant squamous metaplasia in epithelia and marked infiltration of inflammatory cells into the pituitary gland and neuroglial tissues. Most infiltrated cells were lymphocytes and plasma cells, thought to indicate the involvement of long-term underling inflammatory processes in this phenomenon.

CONCLUSION

Long-term subclinical inflammation may be the mechanism of this extraordinary aggressive clinical course. Postoperative steroid administration should be reduced prudently, and careful follow-up imaging is essential in cases of Rathke's cleft cyst with abnormal histological findings.

Expression of merlin, NDRG2, ERBB2, and c-MYC in meningiomas: relationship with tumor grade and recurrence

Meningiomas are common, usually benign tumors of the central nervous system that have a high rate of post-surgical recurrence or regrowth. We determined expression of the proteins merlin, NDRG2, ERBB2, and c-MYC in meningiomas using immunohistochemistry and assessed relationships between protein expression and gender, age, tumor grade, and recurrence or regrowth. The study sample comprised 60 patients, (44 women and 16 men) with a mean age of 53.2 ± 12.7 years. Tumors were classified as grade I (n=48) or grades II and III (n=12). Expression of merlin, NDRG2, ERBB2, and c-MYC was not significantly different statistically with relation to gender, age, or meningioma recurrence or regrowth. Merlin was expressed in 100% of the cases. No statistically significant difference between tumor grade and recurrence or regrowth was identified. Statistically significant differences were identified between the mean age of patients with grade I (54.83 ± 11.60) and grades II and III (46.58 ± 15.08) meningiomas (P=0.043), between strong c-MYC expression and grades II and III (P<0.001), and between partial surgical resection and tumor recurrence or regrowth (P<0.001). These findings reveal the lower mean age among grades II and III meningioma patients than grade I patients, the influence of the protein merlin on tumorigenesis, the association of c-MYC with aggressive meningiomas, and that partial surgical resection is associated with tumor recurrence or regrowth.

Quantitative tumor volumetric responses after Gamma Knife radiosurgery for meningiomas

OBJECT

The reported tumor control rates for meningiomas after stereotactic radiosurgery (SRS) are high; however, early imaging assessment of tumor volumes may not accurately predict the eventual tumor response. The objective in this study was to quantitatively evaluate the volumetric responses of meningiomas after SRS and to determine whether early volume responses are predictive of longer-term tumor control.

METHODS

The authors performed a retrospective review of 252 patients (median age 56 years, range 14–87 years) who underwent Gamma Knife radiosurgery between 2002 and 2010. All patients had evaluable pre- and postoperative T1-weighted contrast-enhanced MRIs. The median baseline tumor volume was 3.5 cm3 (range 0.2–33.8 cm3) and the median follow-up was 19.5 months (range 0.1–104.6 months). Follow-up tumor volumes were compared with baseline volumes. Tumor volume percent change and the tumor volume rate of change were compared at 3-month intervals. Eventual tumor responses were classified as progressed for > 15% volume change, regressed for ≤ 15% change, and stable for ± 15% of baseline volume at time of last follow-up. Volumetric data were compared with the final tumor status by using univariable and multivariable logistic regression.

RESULTS

Tumor volume regression (median decrease of −40.2%) was demonstrated in 168 (67%) patients, tumor stabilization (median change of −2.7%) in 67 (26%) patients, and delayed tumor progression (median increase of 104%) in 17 (7%) patients (p < 0.001). Tumors that eventually regressed had an average volume reduction of −18.2% at 3 months. Tumors that eventually progressed all demonstrated volume increase by 6 months. Transient progression was observed in 15 tumors before eventual decrease, and transient regression was noted in 6 tumors before eventual volume increase.

CONCLUSIONS

The volume response of meningiomas after SRS is dynamic, and early imaging estimations of the tumor volume may not correlate with the final tumor response. However, tumors that ultimately regressed tended to respond in the first 3 months, whereas tumors that ultimately progressed showed progression within 6 months.

Spontaneous alteration from Rathke's cleft cyst to craniopharyngioma--possible involvement of transformation between these pathologies

Both Rathke's cleft cyst and craniopharyngioma are considered to arise from the remnants of Rathke's diverticulum despite the quite different histological characteristics. These two lesions may consist of a disease spectrum extending from Rathke's cleft cyst to craniopharyngioma. However, in spite of increasing evidence of these intermediate histologies, very few cases of the actual transformation from Rathke's cleft cyst to craniopharyngioma have been reported in the same patient. A 47-year-old man suffered from recurrent visual dysfunction. Aspiration and partial cystectomy was performed to a suprasellar massive cystic lesion. The histological diagnosis was Rathke's cleft cyst with a small component of squamous metaplasia. Seven months later, the cyst was re-expanded. The cyst wall was irregularly thickened. Re-operation was performed, and the thickened anterior wall was widely removed. Postoperative histological examination showed multiplication of stratified squamous epithelia forming a papillary arrangement. Ki-67 staining showed positive cells randomly distributed not only in the basal layer but also in various epithelial layers, with a labeling index of more than 20 %. The histological diagnosis was squamous papillary type of craniopharyngioma with high potential of proliferation. Subsequent immunohistochemical examinations showed positive reaction to cytokeratin 8 only in the initial epithelium and negative in the latter epithelium. The present case was thought as an actual evidence of the proposed link between Rathke's cleft cyst and craniopharyngioma. Cytokeratin 8 could be the important examination to differentiate Rathke's cleft cyst from craniopharyngioma.

Rathke's cleft cysts with significant squamous metaplasia--high risk of postoperative deterioration and close origins to craniopharyngioma

BACKGROUND

Rathke's cleft cyst (RCC) with significant squamous and/or stratified epithelium including smooth transition from single cuboidal to squamous epithelium (tRCC) is rare and possibly represents an intermediate form to craniopharyngioma.

METHODS

Twelve patients with histologically confirmed tRCC were retrospectively investigated from a series of 167 cases of RCC and 96 cases of craniopharyngiomas. Clinical data were reviewed, and immunohistochemistry findings for cytokeratins and β-catenin were examined.

RESULTS

All lesions were located in the sella turcica with marked extension to suprasellar cistern. Six of the 12 patients had suffered postoperative re-enlargement, and three of these six patients required more than two additional operations and irradiation. CAM5.2 was positive in the glandular epithelium in all tRCCs and focally positive in the squamous epithelium of all these tRCCs. 34βE12 was positive in the squamous epithelium in all tRCCs and focally positive in the glandular epithelium in all but one tRCC. The findings of cytokeratin expression of tRCCs were very similar to those of craniopharyngioma. β-Catenin showed nuclear translocation in five cases. All patients with nuclear translocation of β-catenin suffered postoperative re-enlargement.

CONCLUSIONS

tRCC carries an extremely high risk of re-enlargement. Cytokeratin expression resembles that in craniopharyngioma, which might indicate a very close origin of these pathologies. Nuclear translocation of β-catenin may be related to the aggressive clinical course.

Prognostic factors of operated Rathke's cleft cysts with special reference to re-accumulation and recommended surgical strategy

BACKGROUND

Rathke's cleft cyst is known as an indolent disease, but has become intractable in a few cases. In this clinical investigation, the initial operative outcomes of Rathke's cleft cyst and the mechanism of re-accumulation were investigated to identify the optimum surgical strategy for the second operation.

METHODS

We conducted a retrospective review of 155 patients with Rathke's cleft cyst (58 males and 97 females, aged from 13 to 84 years) surgically treated between April 1996 and March 2010. The same initial operative strategy was adopted in all patients. Operative outcomes and prognostic factors were investigated.

FINDINGS

Re-accumulation occurred in 27 patients (17.4%), and re-operation was required in eight patients because of neurological deficits (5.2%). Three types of re-accumulating mechanism were identified. First, cysts with cerebrospinal fluid (CSF)-like intensity on magnetic resonance imaging had a higher risk of re-accumulation (logrank test, p < 0.001). The cyst wall should be extensively removed in the suprasellar cistern to allow communication between the cyst and CSF spaces at the second operation. Second, cysts with epithelial transition had a significant higher risk of re-accumulation compared to other types of epithelium (logrank test, p < 0.001). Aggressive removal and irradiation should be performed at the second treatment. Third, classic Rathke's cleft cyst was found in the majority of cases. No change in operative strategy is required at the second treatment with lower risk of intractability.

CONCLUSIONS

Enlargement of Rathke's cleft cyst requiring re-treatment needs selection of surgical strategy according to the individual re-accumulation mechanism.

Rathke's cleft cyst presenting as bilateral abducens nerve palsy

We present a patient with a Rathke's cleft cyst who presented with rapidly progressive bilateral 6th nerve palsy. A 20-year-old woman with a history of cleft palate, hypertension, and hydronephrotic kidneys presented with a one month history of headache, associated with dizziness and diplopia on horizontal gaze. Examination was significant for profound bilateral 6th nerve palsies. Magnetic resonance imaging showed a hypodense mass that filled the sella and compressed the right cavernous sinus without contacting the optic chiasm. Pituitary function was normal. An endoscopic, transnasal transsphenoidal resection of the lesion was performed; microscopic examination revealed a Rathke's cleft cyst. Surgical excision resulted in near complete resolution of the bilateral 6th nerve palsy. Rathke's cleft cysts are an unusual cause of bilateral sixth nerve palsy and represent a potential cause of cranial neuropathy.

Aseptic meningitis after transsphenoidal management of Rathke's cleft cyst: case report and review of the literature

Aseptic meningitis after transsphenoidal surgery (TSS) for treatment of Rathke's cleft cyst (RCC) is a rare complication caused by the leakage of the cyst contents within the subarachnoid space. We present a case of aseptic meningitis occurring after TSS for a RCC. During surgery, the cyst wall was subtotally removed, and intraoperative cerebrospinal fluid (CSF) leakage was observed. The patient developed meningeal signs and symptoms on the first postoperative day. CSF examinations were highly suggestive of aseptic meningitis. Histological examination confirmed a granulomatous inflammatory reaction of the RCC wall. Preexisting inflammation, subtotal cyst wall resection, intraoperative erosion of the diaphragma sellae and placement of a lumbar drain may be risk factors for the development of aseptic meningitis.

Primary Rathke's cleft cyst in the cerebellopontine angle associated with apoplexy

Rathke's cleft cyst (RCC) is a congenital, benign, epithelial tumor and mainly occurs in sellar region and occasionally in suprasellar region; ectopic RCC is exceedingly rare. We report an uncommon RCC in cerebellopontine angle (CPA) associated with RCC apoplexy and investigated the possible hypothesis of its origin. A 12-year-old female student was admitted to hospital for 3-month history of vertigo, headache, nausea, and vomiting and aggravated for 1 week. Magnetic resonance imaging (MRI) revealed a space-occupying lesion with short T1 and long T2 signals in the left CPA and an intracystic floating nodule with hypointensity on T1- and T2-weighted imaging. The patient underwent the total tumor removal via the retrosigmoid approach with a good recovery. Primary RCC was confirmed by pathology. Follow-up MRI showed no recurrence 3.5 years after craniotomy. Primary RCC can occur in CPA and present special neuroimaging features associated with RCC apoplexy. We presumed that a mimicking mechanism of ectopic craniopharyngioma in CPA leads to the formation in the present case. Microsurgical resection is the optimal strategy for management. Further research and longer follow-up are helpful to better understanding the pathogenesis and development history of RCC in CPA.

Adverse radiation effects after Gamma Knife Surgery in relation to dose and volume

INTRODUCTION

The relationship between target volume and adverse radiation effects (AREs) at low prescription doses requires elucidation. The development of AREs in three series of patients treated in the Gamma Knife is analysed in relation to prescription dose and target volume.

MATERIALS AND METHODS

There were three groups. In group 1, there were of 275 patients with meningiomas; in group 2, 132 patients with vestibular schwannomas; and in group 3, 107 patients with arteriovenous malformations (AVMs). The minimum follow-up for each group was more than 24 months. All patients were followed up at six monthly intervals. The patients with tumours received a prescription dose of 12 Gy, which was varied to protect normal structures but not in relation to tumour volume per se. The desired AVM prescription dose was 25 Gy, but this was also reduced to protect normal structures and to keep the total dose within certain pre-defined limits. All AREs refer to intra-parenchymal increased perilesional T2 signal on MR irrespective of clinical correlation.

RESULTS

There was no relationship between tumour volume and the development of ARE in the tumour groups. There was a highly significant relationship between target volume and the development of ARE for the AVMs with their much higher dose. Radiation-induced clinical trigeminal and facial nerve deficits with both vestibular schwannomas and meningiomas were always associated with an increased T2 signal in the neighbouring brainstem parenchyma.

CONCLUSIONS

The relationship between target volume and the risk of adverse radiation effects may not apply with lower prescription doses. Individual radiosensitivity may explain why a minority suffer AREs unrelated to target volume. It is possible that radiation-induced brainstem parenchymal damage with concomitant cranial nerve deficits may be commoner after radiosurgery than is usually thought. If tumour control with lower doses is adequate, radiosurgery could be safely considered for larger targets associated with a high risk from microsurgery.

Gamma Knife surgery for benign meningioma

Object

Meningioma is the most frequent benign tumor treated with Gamma Knife surgery (GKS); however, the assessment of its efficacy and safety in slow-growing tumors is an ongoing process, requiring analysis of long-term results.

Methods

Three hundred sixty-eight patients harboring 400 meningiomas treated between 1992 and 1999 at Na Homolce Hospital were evaluated. The median patient age was 57 years (range 18–84 years). The median tumor volume was 4.4 cm3 (range 0.11–44.9 cm3). The median tumor margin dose to the 50% isodose line was 12.55 Gy (range 6.5–24 Gy). Descriptive analysis was performed in 331 patients (90%); 325 patients had a follow-up longer than 24 months (median 60 months), and six patients were included because of posttreatment complications. The volume of treated tumors decreased in 248 cases (69.7%), remained the same in 99 (27.8%), and increased in nine (2.5%). The actuarial tumor control rate was 97.9% at 5 years post-GKS. Perilesional edema after radiosurgery was confirmed on neuroim-aging in 51 patients (15.4%). The temporary and permanent morbidity rates after radiosurgery were 10.2 and 5.7%, respectively.

Results

A significantly higher incidence of tumor volume increase was observed in men compared with women and in tumors treated with a margin dose lower than 12 Gy. Significant risk factors for edema included an age greater than 60 years, no previous surgery, perilesional edema before radiosurgery, a tumor volume greater than 10 cm3, a tumor location in the anterior fossa, and a margin dose greater than 16 Gy.

Conclusions

Stereotactic radiosurgery is a safe method of treatment for meningiomas. A minimum margin dose of 12 to 16 Gy seems to represent the therapeutic window for benign meningiomas with a high tumor control rate in a mid-term follow-up period.