General

Background: Intraoperative neurophysiologic monitoring has been demonstrated to alert the surgical team to potential injury and can also be used to detect injuries. The purpose of this study was to compare the effects of Sevoflurane and Propofol combined with Remifentanil on Motor Evoked Potentials from cranial nerves and lower limbs during comparable depth of anaesthesia, guided by bispectral index (BIS).

Abstract Objective Intraoperative neuromonitoring (IONM) is used to assess the integrity of neural pathways and aids in optimizing surgical results and avoiding neurologic injury. However, there are few reports of its use and safety in pregnant patients. We will perform a literature review on IONM in pregnancy. In addition to this review, we will report our experience with IONM in a 20-week pregnant patient that presented with a brainstem tumour, which has not been reported before in the literature.

Intraoperative vagal nuclei mapping for a safe entry point in lower brainstem cavernoma B. Almasarwah1, D. Giakoumettis1, E. Chiotaki2, P. Pittaras1, G. Vavoulis1, T. Vogiatzoglou1, K. Vlachos1 1Department of Neurosurgery, KAT General Hospital, Athens, Greece 2Consultant in Intraoperative Monitoring, Atron Health, Athens, Greece Objective: Cerebral cavernous malformations are neurovascular low-flow lesions and occur in the brainstem up to 35% of cases.

Objective: Intraoperative visual evoked potential (VEP) monitoring has become increasingly implemented in ophthalmic artery aneurysm surgery and represents a useful tool for visual assessment.It is generally reported that ophthalmic artery occlusion during clipping and/or surgical manipulation of the vessel does not necessarily result in visual impairment due to its collateral supply from external carotid artery branches, but caution should be taken due to its possible catastrophic implications in visual function.

Introduction and goals: Intraoperative motor evoked potentials (MEP) are commonly used in spinal surgery, including scoliosis correction. Inhaled anesthetics cause significant depression of the MEP, especially in the presence of an initial neurological deficit, as a result of that the search for optimal stimulation parameters to reduce this problem is an important issue. The aim of the study was to compare the effectiveness and the threshold of the transcranial electrical MEP obtained by automatic tracking with single and double train stimulation.

Objective: The aim of this study was to compare stimulation thresholds and current densities in the brain for transcranial motor evoked potentials (tcMEPs) from the hands and feet with linked quadripolar (LQP), M3-M4 and C1-C2 electrode montages. Methods: Twenty-five patients underwent cerebral vascular surgery with tcMEP monitoring. tcMEP voltage thresholds were compared between LQP (C1, M3, C2, M4), C1-C2, and M3-M4 montages. In a finite element model (FEM), hand, arm, and leg regions of interest (ROIs) on the cortical motor homunculus were segmented.

OBJECTIVE The purpose of this study is to assess the relevance of delayed latency of the motor evoked potential in a case of cervical tumor. METHODS Case report of a 35 years old female with progressive right hemiparesis (Medical Research Council Scale– 3/5) due to large infiltrative, contrast enhancing, intra-medullary tumor with an inferior cystic component spanning from the brainstem to C6.

We report a 54-year-old female who presented with an unsteady gait and a recent fall. MRI revealed a right Pons mass, suspected as a breast cancer metastatic disease. A craniotomy for a surgical biopsy was planned. The tumor was of few millimeters in diameter but relatively close to the Facial nuclei, Trigeminal sensory nuclei, and lemniscus pathways. Multimodal intraoperative monitoring (IOM) was used to avoid devastating intra-axial brainstem tumor surgical complications.

We report a 20-year-old male who presents for surgical resection of a dorsally exophytic medullary cavernous malformation incidentally diagnosed two and a half years earlier. The patient experienced a sudden severe headache consistent with a subarachnoid/intraventricular hemorrhage and a 30-minute “locked-in” episode 3-4 days later. He felt unable to move or feel anything from the neck down. The superior and dorsal aspects of the cavernous malformation were slightly more prominent, but no hemorrhage or brainstem injury was shown in the updated MRI.

OBJECTIVE To analyze the contribution of brainstem reflexes in intraoperative neuromonitoring (IONM): blink reflex (BR), H masseter reflex (H), trigeminal hypoglossal reflex (THR), and laryngeal adductor reflex (LAR) during the monitoring of brainstem and posterior fossa surgery, to other well-known cranial nerve monitoring techniques for the trigeminal, facial, vagus and hypoglossal nerves, such as corticobulbar motor evoked potentials (CoMEPs) and free-running EMG.