Awake Surgery for Tumors of the Parietal Lobe: A Preliminary Experience with a New Protocol of Intraoperative Neuropsychological Test for the Monitoring of the Sensory Area Function

Background. Nowadays, there is a lack of studies reporting techniques for the selective monitoring of the primary somatosensory cortex and the adjacent areas of the superior and inferior parietal lobules. We hypothesized a more specific and targeted test for awake surgery for monitoring the sensory area during resection of tumors involving it. Materials and Methods. We collected patients suffering from tumors involving the parietal areas and undergoing awake surgery for the resection. Intraoperative standard neurophysiological monitoring was performed, and we added a new intraoperative test. It consisted of a series of different objects with standard 3D conformations. The patient was asked to recognize the object shape using only the tactile sensibility, without seeing the object itself; in some cases, he was also asked to put the object in the corresponding hole, according to the shape. Results. We collected 6 patients. One patient with a right parieto-occipital lesion, at the stimulation of the anterior cortical margin of the surgical field, showed problems in naming the objects and collocating them in the corresponding spaces, while he was touching them with the left hand. Therefore, the areas of proprioception and perception of the objects were mapped and numbered. This deficit got better in the postoperative days with a total remission of the ideomotor apraxia and the psychomotor slowdown. The other 5 patients did not show an impairment with the new test. Conclusions. This is a preliminary study with the aim of enhancing the specificity of the neuropsychological test performed during awake surgery to allow the surgeon to monitor the neurological functions of the parietal cortex. More cases are needed to validate it.