Introduction: Maximal surgical resection with the preservation of cortical functions is the treatment of choice for brain tumors. Achieving these objectives is especially difficult when the tumor is located in an eloquent area. Navigated transcranial magnetic stimulation (nTMS) is a modern non-invasive, preoperative method for defining motor and speech eloquent areas. Material and methods: Patients with tumors located in motor and speech eloquent areas who presented at our institution between March 2017 and December 2017 were prospectively included. Exclusion criteria were frequent generalized epileptic seizures and cranial implants. For lesions involving motor eloquent areas we performed a nTMS motor mapping and for lesions involving speech eloquent areas we supplemented the motor mapping with speech and language mapping. MR images were exported from the nTMS system in a DICOM format and then loaded in the intraoperative neuronavigation system. Based on these findings, the optimal entry point and trajectory were determined, in order to achieve a maximum surgical resection of the lesion, while avoiding new post-operative neurological deficits. Results: Nineteen patients underwent an nTMS brain mapping procedure between March 2017 and December 2017. In all cases a motor mapping procedure was done, but only in eight cases a speech mapping was also performed. Three patients presented new minor postoperatory deficits that consecutively remitted. The rest of the patients presented no added neurological deficits after surgery. In five cases the preexistent deficit was ameliorated after surgery and in three cases the deficit remitted. In one patient there was no improvement in the neurologic deficit after surgery. Conclusion: nTMS is a reliable tool for the preoperative planning of eloquent area lesions. It must be taken into account that functional areas have a high individual variability. Therefore, knowing preoperatively the extent of the eloquent area helps the neurosurgeon adapt the surgical approach in order to obtain a better functional outcome.

This paper represent a report of a case with ulnar nerve schwannoma(neurilemmoma), benign neurogenic slow-growing, tumors originating from Schwann cells along the course of a nerve (1) (2) (3). Schwannomas are the most common tumors of the peripheral nerves which occur in the adults (0.8-2%) (5). Usually they progress slowly and so they can remain painless swellings for a few years before other symptoms appear. Most of these lesions could be diagnosed clinically, are mobile in the longitudinal plane along the course of the involved nerve but not in the transverse plane (7). EMG, MRI, and ultrasonography are useful tools in the diagnosis. The definitive treatment of benign peripheral nerve schwannomatosis is complete enucleation of the tumor mass without damaging the intact nerve fascicles followed by confirmatory hystopathological examination (12). We present the case of a 62 years old right hand-dominant female who notice a slow increasing bulge over the inner aspect of her distal volar left forearm superior to the wrist, for a longer period of time not exactly specified; this was tracked and associated by pain, tingling and numbness over inner one and half fingers of her left hand in progress until the presentations. A diagnosis of softtissue tumor was presumed clinically. The other investigations were ultrasonography (US), nerve conduction studies (NCSs) such as sensory nerve action potential (SNAP) and compound muscle action potential (CMAP). In this case IRM was suggestive of a benign growth in her left ulnar nerve in the forearm region. Microsurgical techniques were used for ample enucleation of the tumor the distal volar left forearm. Subsequent histopathological examination confirmed the presumed diagnosis of a benign cellular 220 | Martin et al -Benign neurogenic slow-growing solitary neurilemmoma schwannoma. At her last follow-up one month after surgery, the patient was neurological gradually improving sensory and motor function and she is highly satisfied with the results of surgery.

BACKGROUND Frame-based stereotactic biopsy has been for decades the gold-standard method for taking samples of brain tumors for the histopathological diagnostic in cases when surgery was contraindicated. However, novel frameless techniques have been developed in order to facilitate the procedure for the neurosurgeon, and for the patient as well. Preoperative cortical mapping techniques enable the planning of the trajectory with the sparing of eloquent areas. MATERIAL AND METHODS A preoperative cortical mapping using navigated transcranial magnetic stimulation was performed in the case of a 37-year-old male that presented with headache. The MRI scan revealed multiple lesions located frontal lobe and temporal lobe on the right hemisphere and frontal and occipital lobes on the left hemisphere. The results of the preoperative cortical mapping were integrated into the neuronavigation system and used for the planning of the frameless based stereotactic brain biopsy. A biopsy procedure was performed using a robotic arm according to the planned trajectory. RESULTS The targeted lesion was the right frontal one. The planned trajectory took into account the results from the cortical mapping using nTMS, and the eloquent areas were avoided. The robotic arm guided the procedure and aligned to the entry point and trajectory. According to the histopathological result the lesion was a grade II diffuse astrocytoma. There were no perioperative complications. CONCLUSION To our knowledge, this is the first report that describes the use of a robot-guided frameless brain biopsy system combined with the preoperative mapping of the eloquent cortical areas using navigated transcranial magnetic stimulation. This approach is a safe one and carries less burden for the patient as well as for the surgeon.

Introduction: The surgical resection of brain lesions located in language-eloquent areas harbours a great risk for determining new functional deficits. Navigated transcranial magnetic stimulation represents a novel non-invasive cortical mapping method that can be used preoperative to determine language-eloquent areas. Materials and methods: We retrospectively reviewed a prospectively maintained database of patients that underwent preoperative cortical mapping using nTMS between March 2017 and June 2020. Patients older than 18 years old with brain lesions situated in a presumed language eloquent area, that underwent surgical resection of the brain lesion were included in the study. Various parameters such as error rate, number of language-negative sites were assessed. Results: Fourteen patients were included in the study. There were 10 males and 4 females in total. Most of the tumours were in the temporal and frontal lobes (five and four cases, respectively). The histopathological diagnosis was glioblastoma in seven cases, in one case there was an anaplastic astrocytoma and there were two cases of low-grade gliomas. There were three cases of brain metastasis and one cavernoma. The median (range) tumor volume was 25.01 cm3 (0.89 – 86.55 cm3). Gross-total resection (GTR) was achieved in seven cases. The error rate was significantly higher in patients that continued to have an impaired language function after surgical resection (p = 0.016), while the perilesional error rate was higher in patients with preoperative aphasia (p = 0.019). Conclusion: Our findings suggest that a lower tumour volume to perilesional negative stimuli ratio is associated with an extended surgical resection of brain tumours located in language-eloquent areas and that patients that presented with aphasia and have a high error rate have a worse functional prognosis. Through nTMS preoperative cortical mapping of language-eloquent areas, the neurosurgeon has more insight regarding the cortical function and can maximize the surgical resection, while avoiding the onset of new functional deficits.

Symptomatic pontine cavernous malformations carry a high risk of recurrent bleeding, which may result in permanent neurological deficit. Such lesions require surgical management that can be challenging to the neurosurgeon due to their anatomical location and their proximity to delicate neural structures. An ideal surgical approach should provide maximal surgical resection with minimal morbidity. We present the case of a 48-year-old woman with a pontine cavernoma with repeated spontaneous intralesional hemorrhages, resected using a telovelar approach extended by a minimal incision of the inferior vermis, with good surgical outcome. The telovelar approach provided a good access to the lateral recesses and the foramen of Luschka, while the lower vermian incision provided a greater vertical working angle inside the ventricle.