Cystic lesions associated with intracranial meningiomas. Report of three cases

Atypical Meningioma With Large Cyst-Case Report-

A 29-year-old male presented with loss of consciousness and generalized seizure, followed by right hemiparesis and speech disturbance. Computed tomography and magnetic resonance imaging showed a solid, enhanced tumor with a cyst in the left frontal area with surrounding edema and mild mass effect. The cyst wall was also enhanced. The preoperative diagnosis was cystic falx meningioma. The tumor was totally resected, but most of the cyst wall adhered tightly to the surrounding brain and could not be removed. Histological examination revealed atypical meningioma and tumor cells in the cyst wall. The patient received local radiotherapy to the residual cyst wall with a total dose of 50 Gy.

Do microelectrode techniques increase accuracy or decrease risks in pallidotomy and deep brain stimulation? A critical review of the literature

Several recent publications have stated that the use of microelectrode recording (MER) during pallidotomy or deep brain stimulation (DBS) contributes to decreasing risks and side effects of surgery, and that such a technique is a prerequisite for minimizing lesion size and for accurate placement of the stereotactic lesion or the DBS electrode. To evaluate the consistency of these statements, we reviewed hundreds of papers and congress reports on MER- and non-MER-guided procedures published since 1992. This review showed that MER groups published more often than non-MER groups. While side effects of surgery were not uncommon in both groups, the rate of severe complications, such as hematoma, and mortality appeared to be higher when microelectrodes were used, both in ablative surgery and in DBS procedures. Besides, the nonaccurate placement of lesions or DBS electrodes, as assessed on published MRI figures, was not uncommon in MER publications. Lesion volume was, when reported, not different in both techniques. The electrical parameters of stimulation of implanted electrodes in the thalamic ventral intermediate (Vim) nucleus for treatment of tremor were higher in MER-guided surgery. The available literature suggests that MER techniques may increase the risks of surgery without enhancing its accuracy, compared to MRI-based macrostimulation techniques. To date, there is no randomized trial by one and the same group on the use of micro- versus macroelectrodes in surgery for movement disorders. A prerequisite for such a trial in the future must imply that the investigators have an equal nonprejudiced attitude towards, and equal confidence and experience in, either technique. Since such a prerequisite does not exist so far in the functional stereotactic community, a critical and comparative study of the available literature remains the only way to evaluate the pros and cons of either technique, in terms of targeting accuracy and surgical complications.