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1.  P07.02THE ROLE OF INTRAOPERATIVE NEUROPHYSIOLOGICAL MONITORING IN SURGERY OF INTRADURAL EXTRAMEDULLARY SPINAL CORD TUMORS 
Neuro-Oncology  2014;16(Suppl 2):ii48-ii49.
INTRODUCTION: Surgery of intradural extramedullary spinal cord tumors (IESCT) carries the risk of new neurological deficits in the post-operative period. Intraoperative neurophysiological monitoring (IONM) represents the most effective technique able to improve clinical and functional outcomes, which are obtained through identification and real-time intraoperative monitoring of spinal cord, giving informations about neurological conduction of both, spinal cord long pathways and cauda equina radices. The most widely used and reliable techniques are somatosensory evoked potentials (SEPs), motor evoked potentials (MEPs) and D-wave registration. Although in the literature there are recent evidences of the IONM usefulness, there are not uniform opinions about the different techniques employed, and, their use in IESCT. In the present study we describe the results in our 2-year experience at the Neurosurgery of the University of Messina Hospital. MATERIALS AND METHODS: Our protocol includes evaluation of SEPs from posterior tibial nerve stimulation, MEPs obtained with elevate voltage electrical transcranial stimulation (through multiple myomeric registration of motor evoked responses from inferior limbs), D-Wave registration (through epi- and intradural registration after single pulse electrical transcranial stimulation) in spinal tumor surgery. RESULTS: We did not recorded any intraoperative complication by the use of our IONM protocol. In all patients IONM was useful for correct neurological and functional identification of spinal cord. We observed an optimal correlation between neurological examination on admission and responses from IONM of inferior limbs SEPs and MEPs. In fifty percent of patients, the D-wave registration was the most useful intraoperative tool, due to the lack of motor and somatosensory evoked responses. We matched all pre and post-operative neurological and neurophysiological data, along with tumors' features (localization, dimensions and histology) in order to quantify the impact of IONM on outcome. In our series, none of the patients presented with neurological worsening in the post-operative period. Conversely, surgical treatment of IESCT lead to a significant improvement of neurological status of our patients. CONCLUSIONS: Our preliminary data, although based on a limited series of patients evaluated at a single institution, confirm the role of IONM as an essential tool in operative work-up of all spine surgeries, including IESCT, to achieve an optimal post-operative functional outcome. This study gives further evidences about relevance, impact and usefulness of IONM in IESCT surgery.
doi:10.1093/neuonc/nou174.184
PMCID: PMC4185532
2.  P16.11A NEW TECHNIQUE OF “FUNCTIONAL” DTI TRACTOGRAPHY OF THE CORTICO-SPINAL TRACT BASED ON NAVIGATED BRAIN STIMULATION FOR SURGERY OF BRAIN TUMORS LOCATED NEAR THE MOTOR PATHWAY 
Neuro-Oncology  2014;16(Suppl 2):ii80.
INTRODUCTION: Surgery of brain tumors located near the motor pathway still represents a challenge because of the risk of significant post-operative morbidity. In the last few years, there have been an increasing interest for imaging techniques that could reliably define the spatial relationship between a tumor and the adjacent eloquent areas before surgery. Among these techniques, navigated brain stimulation (NBS) and DTI tractography of the cortico-spinal tract (CST) are considered the most promising. However, tractography still presents spatial inaccuracies that can be reduced by using the NBS map of the motor cortex as seeding region for the tract reconstruction. The objective of this study is to: describe a new technique of a “functional” NBS-based DTI tractography of the CST able to define its somatotopic organization; verify its accuracy by using direct subcortical stimulation (DSS); compare its reliability with the standard tractography; assess its impact on surgical strategy and motor outcome in patients operated for brain tumors located near the motor pathway. MATERIALS AND METHODS: We prospectively enrolled patients operated at the Neurosurgical Clinic of the University of Messina, Italy, between 2012 and 2014. All patients were submitted to the “functional” NBS-based DTI tractography of the CST. We reconstructed the motor pathway pre- and intra-operatively for the surgical planning as a guide for the lesion resection. In addition, after surgery, we performed the standard CST tractography. We assessed the accuracy of the CST somatotopic reconstruction using the DSS. Then, we compared the reliability of our technique with the standard tractography, analyzing the number of tract fibers obtained using the two techniques and the degree of overlapping of the CST cortical end-regions with the NBS map of the motor cortex. Lastly, we assessed the impact of our technique on surgical strategy using a multiple choice questionnaire provided to the surgeon, and assessed its efficacy in avoiding post-operative motor deficits using the Medical Research Council (MRC) scale. RESULTS: In 25 cases cases we obtained a somatotopic reconstruction of the CST, distinguishing between functionally different fiber bundles (arm, face and leg fibers) which matched with the DSS. The “functional” technique was more accurate than the standard tractography, providing useful information to the surgeon in 76% of cases. Lastly no worsening of the MRC score was recorded in all cases. CONCLUSIONS: The “functional” NBS-based DTI tractography of the CST is a reliable planning tool for surgery of brain tumors located near the motor pathway. It provides helpful anatomical and functional information about the motor pathway that can be used before and during surgery. It is also more accurate and less operator-dependent as compared to the standard tractography and is effective in avoiding post-operative motor deficits.
doi:10.1093/neuonc/nou174.307
PMCID: PMC4185669
3.  ABNORMAL SENSORIMOTOR PLASTICITY IN ORGANIC BUT NOT IN PSYCHOGENIC DYSTONIA 
Brain : a journal of neurology  2009;132(Pt 10):2871-2877.
Dystonia is characterised by two main pathophysiological abnormalities: reduced excitability of inhibitory systems at many levels of the sensorimotor system, and increased plasticity of neural connections in sensorimotor circuits at a brainstem and spinal level. A surprising finding in two recent papers has been the fact that abnormalities of inhibition similar to those in organic dystonia are also seen in patients who have psychogenic dystonia. To try to determine the critical feature that might separate organic and psychogenic conditions, we investigated cortical plasticity in a group of 10 patients with psychogenic dystonia and compared the results with those obtained in a matched group of 10 patients with organic dystonia and 10 healthy individuals. We confirmed the presence of abnormal motor cortical inhibition (short interval intracortical inhibition, SICI) in both organic and psychogenic groups. However, we found that plasticity (paired associative stimulation, PAS) was abnormally high only in the organic group, while there was no difference between the plasticity measured in psychogenic patients and healthy controls. We conclude that abnormal plasticity is a hallmark of organic dystonia; furthermore it is not a consequence of reduced inhibition since the latter is seen in psychogenic patients who have normal plasticity.
doi:10.1093/brain/awp213
PMCID: PMC2997979  PMID: 19690095
associative plasticity; organic dystonia; psychogenic dystonia; paired associative stimulation; transcranial magnetic stimulation

Results 1-4 (4)