RESUMEN
OBJECT: Few experiences of insular surgery have been reported. Moreover, there are no large surgical studies with long-term follow-up specifically dedicated to WHO Grade II gliomas involving the insula. In this paper, the author describes a personal consecutive series of 51 cases in which patients underwent surgery for an insular Grade II glioma. On the basis of the functional and oncological results, advances and limitations of this challenging surgery are discussed. METHODS: Fifty-one patients harboring an insular Grade II glioma (revealed by seizures in 50 cases) underwent surgery. Findings on preoperative neurological examination were normal in 45 patients (88%). All surgeries were conducted under cortico-subcortical stimulation, and in the case of 16 patients while awake. RESULTS: Despite an immediate postoperative worsening in 30 cases (59%), the condition of all but 2 patients (96%) returned to baseline or better. Postoperative MR imaging demonstrated that 77% of resections were total or subtotal. Ten patients underwent a second or third surgery, with no additional deficit. Forty-two patients (82%) are alive with a median follow-up of 4 years. CONCLUSIONS: This is the largest reported experience with insular Grade II glioma surgery. The better knowledge of the insular pathophysiology and the use of intraoperative functional mapping allow the risk of permanent deficit to be minimized (and even enable improvement in quality of life) while increasing the extent of resection and thus the impact on the course of the disease. Therefore, surgical removal must always be considered for insular Grade II glioma. However, this surgery remains challenging, especially within the anterior perforating substance and the posterior part of the (dominant) insula. Additional surgery can be suggested in cases in which the first resection is not complete.
Asunto(s)
Neoplasias Encefálicas/cirugía , Corteza Cerebral , Glioma/cirugía , Adulto , Neoplasias Encefálicas/mortalidad , Femenino , Estudios de Seguimiento , Glioma/mortalidad , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Tasa de Supervivencia , Resultado del TratamientoRESUMEN
The superior frontal gyrus (SFG) is thought to contribute to higher cognitive functions and particularly to working memory (WM), although the nature of its involvement remains a matter of debate. To resolve this issue, methodological tools such as lesion studies are needed to complement the functional imaging approach. We have conducted the first lesion study to investigate the role of the SFG in WM and address the following questions: do lesions of the SFG impair WM and, if so, what is the nature of the WM impairment? To answer these questions, we compared the performance of eight patients with a left prefrontal lesion restricted to the SFG with that of a group of 11 healthy control subjects and two groups of patients with focal brain lesions [prefrontal lesions sparing the SFG (n = 5) and right parietal lesions (n = 4)] in a series of WM tasks. The WM tasks (derived from the classical n-back paradigm) allowed us to study the impact of the SFG lesions on domain (verbal, spatial, face) and complexity (1-, 2- and 3-back) processing within WM. As expected, patients with a left SFG lesion exhibited a WM deficit when compared with all control groups, and the impairment increased with the complexity of the tasks. This complexity effect was significantly more marked for the spatial domain. Voxel-to-voxel mapping of each subject's performance showed that the lateral and posterior portion of the SFG (mostly Brodmann area 8, rostral to the frontal eye field) was the subregion that contributed the most to the WM impairment. These data led us to conclude that (i) the lateral and posterior portion of the left SFG is a key component of the neural network of WM; (ii) the participation of this region in WM is triggered by the highest level of executive processing; (iii) the left SFG is also involved in spatially oriented processing. Our findings support a hybrid model of the anatomical and functional organization of the lateral SFG for WM, according to which this region is involved in higher levels of WM processing (monitoring and manipulation) but remains oriented towards spatial cognition, although the domain specificity is not exclusive and is overridden by an increase in executive demand, regardless of the domain being processed. From a clinical perspective, this study provides new information on the impact of left SFG lesions on cognition that will be of use to neurologists and neurosurgeons.