Skull base meningioma : Surgical and adjuvant treatment with clinical and PET evaluation

Abstract: The treatment strategy for skull base meningiomas remains a controversial issue. Because of the proximity of these tumours to critical neurovascular structures, the risk for vascular damage and new cranial neuropathies postoperatively is significant. To avoid unacceptable neurological deficits the surgical treatment strategy includes different surgical approaches and a subtotal removal of these tumours in some cases. However, because the rate of recurrence and progression is significant in these patients, a demand for adjuvant treatment and better prognostic methods is called for so that treatment and follow-up can be tailored to each patient. Accordingly, we have chosen to evaluate general outcome and facial nerve function after translabyrinthine and transcochlear approaches for cerebellopontine angle (CPA) meningiomas. Furthermore, we have evaluated two adjuvant treatments, namely, irradiation by high-energy proton beams and medical treatment with interferon-alpha as well as evaluation of the treatment effect with 11C-L-methionine PET. In addition, we have evaluated a new PET tracer (76Br-BrdU) for "in vivo" determination of the growth potential of intracranial tumours. Conclusion: The translabyrinthine and transcochlear approaches are apparently safe surgical procedures in the treatment of CPA meningiomas. Proton beam therapy is technically feasible as suggested by the fact that only minimal side effects were observed. Moreover, none of the meningiomas treated have shown progression during a 36-month follow-up. Our results indicate that IFN-alpha can be an effective oncostatic treatment for certain patients with meningiomas. The 11C-L-methionine PET method might be used as a complement to CT or MRI in the evaluation of the effect of proton beam and IFN-alpha treatment in meningiomas. The present attempt failed to demonstrate that the PET tracer 76Br-BrdU could be used for the non-invasive characterisation of growth potential in brain, tumors.