Analysis of the influence of the variable size on the characteristics and behavior of meningiomas

Volume assessment of intracranial large meningiomas and considerations about their microsurgical and clinical management

OBJECTIVE

To assess the volume of large intracranial meningiomas and analyse their different microsurgical and clinical managements.

METHOD

The volume of 45 large meningiomas treated in our department during the last 9.5 years was retrospectively assessed using recorded neuronavigation data. The seven most employed microsurgical strategies and five important factors influencing the patient's outcome (tumor location, grade of peritumoral brain swelling, grade of brain atrophy, entrapment of neurovascular structures and the management of the vascular infused fluid volume) were individually analysed. The follow-up ranged from 14 to 84 months.

RESULTS

The assessed volumes exceed 100 cm(3) in 38 supratentorial and 45 cm(3) in seven infratentorial tumors. The highest averaged volume in this series was assessed by tuberculum sellae and olfactory meningiomas (174 cc). A complete resection was achieved in 39 patients and was not influenced by the tumor volume. However, an averaged volume difference of 60 cc was observed between anterior skull base tumors in which their averaged greatest diameter variation was only 1.5 cm. Twelve of 24 patients with deep located tumors and entrapped neurovascular structures presented accentuated brain swelling. A new permanent post-operative neurological deficit was observed only in two patients. In the other patients, cranial nerve deficits, pre-operative hemiparesis and superior cerebral functions improved to varying degrees. Four cases with subtotal resection showed stable residual volumes after 4.5 year follow-up. Three cases underwent additional radiosurgery.

CONCLUSION

Tumor volume assessment allows an improved meningioma size differentiation. Despite the large volume of the tumors in this series, satisfactory resection was still possible using single-stage procedures. Individual microsurgical strategies and fluids management contributed to reducing patient's morbi-mortality.

¹H-MRS of intracranial meningiomas: what it can add to known clinical and MRI predictors of the histopathological and biological characteristics of the tumor?

OBJECTIVE

The main goal of the present study was evaluation of proton magnetic resonance spectroscopy (¹H-MRS) in diagnosis of histopathologically aggressive intracranial meningiomas.

METHODS

Single-voxel ¹H-MRS of 100 intracranial meningiomas was performed before their surgical resection. Investigated metabolites included mobile lipids, lactate, alanine, N-acetylaspartate (NAA), and choline-containing compounds (Cho). According to criteria of World Health Organization (WHO) 82 meningiomas were assigned histopathological grade I, 11 grade II, and 7 grade III. The MIB-1 index varied from 0% to 27.3% (median, 1.6%). In 43 cases tight adhesion of the tumor to the pia mater or brain tissue was macroscopically identified at surgery. The consistency of 49 meningiomas was characterized as soft, 26 as hard, and 25 as mixed.

RESULTS

No one metabolic parameter had statistically significant association with histopathological grade and subtype, invasive growth, and consistency of meningioma. Univariate statistical analysis revealed greater ¹H-MRS-detected Cho content (P=0.0444) and lower normalized NAA/Cho ratio (P=0.0203) in tumors with MIB-1 index 5% and more. However, both parameters lost their statistical significance during evaluation in the multivariate model along with other clinical and radiological variables. It was revealed that non-benign histopathology of meningioma (WHO grade II/III) is mainly predicted by irregular shape (P=0.0076) and large size (P=0.0316), increased proliferative activity by irregular shape (P=0.0056), and macroscopically invasive growth by prominent peritumoral edema (P=0.0021).

CONCLUSION

While ¹H-MRS may be potentially used for the identification of meningiomas with high proliferative activity, it, seemingly, could not add substantial diagnostic information to other radiological predictors of malignancy in these tumors.