gms | German Medical Science

ESBS 2005: Skull Base Surgery: An Interdisciplinary Challenge
7. Kongress der Europäischen Schädelbasisgesellschaft & 13. Jahrestagung der Deutschen Gesellschaft für Schädelbasischirurgie

18. - 21.05.2005, Fulda

The use of stereotactic radiosurgery in the management of meningiomas involving the cavernous sinus

Meeting Contribution

Suche in Medline nach

  • J. Rowe - National Centre for Stereotactic Radiosurgery, Royal Hallamshire Hospital, Sheffield, UK
  • I. Malik - National Centre for Stereotactic Radiosurgery, Royal Hallamshire Hospital, Sheffield, UK
  • M. Radatz - National Centre for Stereotactic Radiosurgery, Royal Hallamshire Hospital, Sheffield, UK
  • A.A. Kemeny - National Centre for Stereotactic Radiosurgery, Royal Hallamshire Hospital, Sheffield, UK

ESBS 2005: Skull Base Surgery: An Interdisciplinary Challenge. 7th Congress of the European Skull Base Society held in association with the 13th Congress of the German Society of Skull Base Surgery. Fulda, 18.-21.05.2005. Düsseldorf: German Medical Science GMS Publishing House; 2009. Doc05esbs59

doi: 10.3205/05esbs59, urn:nbn:de:0183-05esbs594

Veröffentlicht: 27. Januar 2009

© 2009 Rowe et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielfältigt, verbreitet und öffentlich zugänglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

Text

Introduction

Meningiomas involving the cavernous sinus pose particular management dilemmas. Their intimate relationship to the carotid artery and cranial nerves II–VI generally means that they cannot be resected and surgery carries with it a significant risk of serious morbidity. These considerations are reflected by the fact that 47% of our Gamma knife stereotactic radiosurgery treatments for meningiomas were for tumours involving the cavernous sinus. In this we include not only meningiomas arising primarily in the cavernous sinus, but also those that have arisen elsewhere, but extended into the sinus.

Methods

Patient details

Between 1994 and 2000 we treated 144 patients with meningiomas involving the cavernous sinus. Seventy patients received radiosurgery as a primary treatment largely for tumours arising within the cavernous sinus itself, 74 patients had had previous surgery, a residual or recurrent cavernous sinus component of the disease being treated. There was the expected (78%) female sex preponderance, with a mean age at treatment of 50±13 years and a mean treatment volume of 7.2±6.6 cm2. All treatments were carried out using MRI localisation defining not only the tumour, but the optic pathways. All treatments were delivered with the Leksell Gamma knife prescribing an average of 20±4 Gy to the tumour margin using 7.1±2.7 isocentres per treatment. As policy we plan the treatments around the optic apparatus, aiming to keep the optic nerves and chiasm outside the 8Gy line, and accepting at times that the apex of the tumour may receive less radiation than the base of the tumour. This approach has previously been described [1].

Follow up and analysis

All patients were followed up radiologically and clinically either by our own service or by referring units. Where follow up imaging was performed elsewhere, this was systematically requested and measured by our own service using a volumetric software package. Overall the mean follow up was 42±22 months. Tumour control was defined by there being no further treatment undertaken for the tumour and no evidence of growth on follow up scan. Control rates were calculated actuarially. Values are expressed as mean ± standard deviation.

Results

Seven of the 144 tumours underwent further treatment, surgical resection in three, fractionated radiotherapy in two and further stereotactic radiosurgery in two. There was concern about a further five tumours growing, although no further treatment had been undertaken for these. This equates to a five year actuarial growth control rate of 91%.

In terms of complications: four patients had new or worsening diplopia, resolving in two; three patients had new or worsening facial numbness which resolved in one. No patient had worsening visual function and no patient developed side effects from brain stem changes. This gives an overall persisting complication rate of less than 3%, the complications all being the result of cranial neuropathies.

Discussion

Gamma knife stereotactic radiosurgery offers an attractive management strategy for the cavernous sinus component of meningiomas involving this structure. Control rates appear to be high, of the order of 90% at 5 years, not only in this, but in other comparable series [2], [3], [4]. Complications are infrequent and in our experience are limited to facial numbness and diplopia.

In terms of advising patients about the active treatment alternatives, the role of microsurgical resection in these patients appears limited. This is illustrated by the fact that over half of the tumours in this series were recurrences or residual tumour deemed non-resectable after previous surgery. Even when there were concerns about further tumour growth after radiosurgery, it was only a quarter of these patients (3 of 12) who underwent further surgical explorations.

The alternative active management is a radiation treatment. The scientific debate here is probably not whether this should be delivered by a Gamma knife or by a linear accelerator, but rather whether it should be delivered as a single high dose fraction or as fractionated therapy. The reason for this statement is that both Gamma knives and linear accelerators deliver photons of a similar energy, although there may be differences in planning, quality assurance and accuracy between the two radiation tools and indeed there may be further differences between different linear accelerator systems. The issue of whether to fractionate a treatment or deliver it as a single high dose of radiation is complex and there are no controlled trials addressing these issues. Most of the literature on the fractionated radiotherapy treatment of meningiomas has not used stereotactic localisation and indeed has frequently extended back into the pre-CT and pre-MRI era, control being essentially a freedom for clinical symptom progression [5]. Whilst at best control rates comparable to the radiosurgical series have been quoted from this material, there are issues of patient selection, results being worse if actively recurrent tumours are being treated.

Conceptually, single fraction treatments differ from fractionated therapy in a number of respects. Stereotactic localisation is mandatory to provide precise targeting to safeguard the adjacent tissues. Radiobiologically the effects may be very different as high dose single fraction treatments do have a particular thrombo-obliterative effect which is of course the basis of the use of radiosurgery in treating arteriovenous malformations. Such a thrombo-obliteration may be important in treating vascular tumours such as meningiomas. Conventional fractionation has an advantage if the target tumour is more radiosensitive than the surrounding tissues as the latter can recover between the individual fractions being delivered. Part of the radiosensitivity relates to the rate of cell turnover, the principle being that the faster the cells are cycling, the more likely that repeated fractions will catch cells in different phases of the cell cycle. This of course is more a consideration with fast growing malignant tumours than with slow growing meningiomas and one might speculate that the more benign the target tumour, the less there will be an advantage with fractionated therapy.

Conclusions

Radiosurgery is developing as an effective therapy for meningiomas which are difficult to access surgically. With modern planning techniques it has an attractively low morbidity. There are no controlled trials comparing fractionated radiotherapy treatments with single high dose radiosurgical treatments, but importantly there may be significant radiobiological differences which could influence the choice of technique.


References

1.
Rowe et al. Stereotact Funct Neurosurg. 2004;82:169-74.
2.
Roche et al. J Neurosurg. 2000;93(Suppl 3):68-73.
3.
Shin et al. J Neurosurg. 2001;95:435-9.
4.
Lee et al. J Neurosurg. 2002;97:65-72.
5.
Malik et al. Br J Neurosurg. 2005;19:13-20.