5.4 Oligodendroglioma
This is another kind of glioma (see classification). If its cells are only oligodendrocytes, then it is fairly benign. If it contains astrocytes, it may become more aggressive. Oligodendroglioma is a tumor of the cerebral hemispheres and its presenting symptoms frequently include epilepsy. There are also anaplastic and/or malignant oligodendrogliomas. The most important therapy is surgery. When its location is favorable, "radical" removal should be attempted. The operation should be planned on the basis of data from functional MRI correlated with those provided by the neuronavigator. Adjuvant therapies are unnecessary in cases of pure low-grade oligodendroglioma, with no residual tumor at post-operative MRI.
RMN di un oligodendroglioma
Fig.5.13: MRI of a left parietal oligodendroglioma (red arrows), with some astrocytoma components.
Studio al neuronavigatore di un oligodendroglioma
Fig.5.14: Same case at the neuronavigator (tumor in red), permitting to select the best trajectory.
Demarcazione e asportazione dell'oligodendroglioma
Fig.5.15: Thanks to available data, the tumor is surgically isolated under the operating microscope and then removed (in this lucky case, en bloc). Bottom right: the removed tumor.
RMN postoperatoria rimozione dell'oligodendroglioma
Fig.5.16: Post-operative MRI showing "total" removal of the glioma. The arrow points to the trajectory and to the residual cavity.
Malignant oligodendrogliomas (WHO grades III and IV) behave like their astrocytoma analogs.
Oligodendroglioma is a rather chemo-sensitive brain tumor, i.e. it responds to chemotherapy better than other gliomas. The study of the tumor genes permits a good prediction of the chemo-sensitivity of this type of tumors.
There are several chemotherapeutic protocols; the most popular and effective ones are based on a combination of Procarbazine, Vincristine and CCNU (PCV) and on the use of Temozolomide alone or with radiotherapy.
Gliomas, with all their biological variations, may occur also in the spinal cord. Astrocytomas of the spinal cord are diffuse and generally difficult to remove. For their diagnosis, MRI is indicated. Gliomas of the spinal cord are rare. Surgical exploration may be indicated, as post-operative clinical worsening is a frequent occurrence. Sometimes, very good surgical results may be obtained (see next paragraph).