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P163: Intraoperative monitoring of cranial nerves function in surgery of skull base tumours
S90
Abstracts of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339
Results: Intraoperative VEP monitoring was feasible in 27 patients (82%) and not feasible in 6 patients with severe preoperative visual dysfunction. N75 had median amplitude 2.6μV (range 0.8-7.7μV) and latency 84ms (57142ms). P100 had medianamplitude 2.0μV (0.5-7.0μV) and latency 102ms (75-161ms). N75 amplitude differed significantly between patients with preoperative normal and impaired visual function (P <0.05). Of all recording channels, Oz/A+ provided the largestnumber of stable VEPs (36/51, 71%). Of the 23 patients without N75 amplitude loss, 2 showed improved visual function postoperatively, 18 showed no change and 3 developed hemianopsia. This resulted in a specificity of 96% and a negative predictive value of 89%. Temporary VEP loss was observed in 3 patients and visual function was preserved. Permanent VEP loss was seen in 1patient without new postoperative visual impairment. Conclusions: Intraoperative VEP monitoring was feasible in all patients with intact preoperative visual function. Minor visual field defects such as quadrantanopsia did not affect VEP monitoring. Feasibility of intraoperative VEP monitoring depended strongly on the integrity of visual function. Patient selection should consider visual function.
P163 Intraoperative monitoring of cranial nerves function in surgery of skull base tumours M. Hupalo, D.J. Jaskolski Barlicki Univeristy Hospital, Neurosurgery, Lodz, Poland Question: Developing technique of mapping of cranial nerves (III, IV, VI, VII, IX - XII) along with their continuous intraoperative monitoring in surgery of skull base tumours and assessement of utility of this technique in clinical practice. Material and methods: There were 16 patients (12 females and 4 men, mean age 50 years) with giant tumours of skull base (meningiomas: 5 petroclival, 2 of cavernous sinus, 1 of foramen magnum, 2 of petrous bone, 1 epidermoid in cerebello-pontine angle and in cavernous sinus, 2 chemodectomas, schwannomas: one of the IX nerve and one of the V nerve, inflammatory tumour in infratemporal fossa, ethmoid cells and sphenoid sinus. All the cases were operated on with mapping and monitoring of the cranial nerves: III nerve – 8 cases, IV – 11, VI – 11, VII – 12, IX – 8, X – 8, XI – 7 and XII – 4. The nerves were identified by means of nerve conduction velocity (NCV) and monitored with free run EMG recorded from muscles innervated by respective cranial nerves. Characteristic changes in recording and warning sounds heralded an imminent nerve damage thus providing warning to a surgeon. Results: The mapping was successful in 15 patients. The failure happened in a giant petrous bone meningioma in which the monitoring of oculomotor nerves (III, IV, VI) and and facial nerve was attempted. Long-lasting and frequent irritation of a nerve, despite preservation of its anatomical integirity, resulted in the adequate neurological deficit present for up to a few months after surgery. Particularly, facial nerve was often affected in such a way. On the other hand, adbucens nerve palsy occurring despite its identification turned out to be the most frequently encountered adverse event. Conclusions: Intraoperative neurophysiological mapping of the oculomotor nerves (III, IV, VI), facial nerve and lower cranial nerves is possible in almost all patients with skull base tumours. In majority of cases an early warning allows sparing of the affected nerve.
P164 Intraoperative neurophysiologic monitoring of surgical and endovascular treatment of pediatric arteriovenous malformations V. Nguyen, S. Avila, S. Cho, L. Lee, S. Le, J. López Stanford University, School of Medicine, Department of Neurology, Stanford, United States Objective: To analyze how intraoperative neurophysiologic monitoring (IONM) changes correlate with new postoperative deficits in the surgical and endovascular treatment of pediatric arteriovenous malformations (AVMs). Background: IONM aids in identifying neurological compromise during procedures that place the nervous system at risk. Cerebral AVMs are vascular anomalies that pose a risk for hemorrhage, stroke, or seizures. The utility of IONM in the treatment of pediatric AVMs has not been well documented. Design/methods: 320 cases in 147 patients ages 10 days to 18 years were examined, including 213 endovascular embolizations and 107 surgi-
cal resections, all monitored with EEG, SSEPs, MEPs, EMG, and/or BAEPs. Preoperative and postoperative neurological deficits were analyzed using electronic medical records. IONM changes were defined as being either transient (resolving by the end of monitoring) or persistent (not resolving). Results: 43 (13.4%) cases had IONM changes, 14 were persistent, and of those, 9 (64.2%) had post-operative deficits. 29 changes were transient, but only 6 (20.7%) of those had post-operative deficits. 277 (86.6%) cases lacked IONM changes, 6 (2.2%) of these had new deficits associated with cerebral hypoperfusion or edema after the end of monitoring, and 7 (2.5%) developed new deficits outside of the neurologic territory monitored. 28 (8.8%) cases presented IONM changes but did not have post-operative deficits; most of these were associated with alterations in surgical management or pre-embolization methohexital testing (performed to prevent permanent neurological injury). Conclusions: Persistent IONM changes had a strong correlation with new post-operative deficits. Transient IONM changes, including those resolving after alterations in surgical management or pre-embolization methohexital testing, had a much lower risk of new deficits. Therefore, IONM can be a useful tool in pediatric AVM cases, not only in predicting neurological compromise, but also in identifying when to alter management.
P165 Spinal intradural tumours: a single centre experience L. Cabañes Martínez 1 , I. Regidor 1 , G. de Blas 1 , F. Abreu 2 , R. Carrasco 2 , M. del Álamo 2 , L. Ley 2 1 Hospital Ramón y Cajal, Clinical Neurophysiology, Madrid, Spain; 2 Hospital Ramón y Cajal, Neurosurgery, Madrid, Spain Question: Primary spinal cord tumours represent 2% to 4% of all central nervous system neoplasms and are anatomically separable into two broad categories: intradural intramedullary and intradural extramedullary. We present our experience treating this kind of tumours in the last 10 years, with an especial focus on the use of intraoperative neurophysiologic monitoring (IOM). Methods: We have performed a retrospective study within our institution, from an epidemiologic, clinical, radiologic and surgical point of view, including the use of IOM. Results: A total of 93 patients, ages between 22 and 81 years old. The most frequent clinical presentation was motor deficit and pain. There was great histological variation, but neurinomas, meningiomas and ependymomas were more frequent. Multimodal IOM was used in 41% of the cases. We observed that in the group of monitorized patients the rate of neurological sequelae was lower that in the non-monitorized group. Conclusions: The use of IOM in primary intradural spinal cord tumours reduces the incidence of neurological complications. IOM can identify neurological injury with excellent sensitivity.
P166 Continuous dynamic mapping of the corticospinal tract during surgery of motor eloquent brain tumors K. Seidel, J. Beck, P. Schucht, A. Raabe Inselspital University Hospital Bern, Neurosurgery, Bern, Switzerland Question: We developed a new mapping protocol to overcome the temporal and spatial limitations of classical subcortical mapping of the corticospinal tract (CST). The feasibility and safety of continuous (0.4-2 Hz) and dynamic (at the site of and synchronized with tissue resection) subcortical motor mapping was evaluated. Methods: We prospectively studied 128 patients who underwent tumor surgery adjacent to the CST (<1 cm using diffusion tension imaging (DTI) and fiber tracking) with simultaneous subcortical monopolar motor mapping (short train, inter-stimulus interval (ISI) 4.0 ms, pulse duration 500 μs) and a new acoustic motor evoked potential (MEP)-alarm. Continuous (temporal coverage) and dynamic (spatial coverage) mapping was technically realized by integrating the mapping probe at the tip of a new suction device with the concept that this device will be in contact with the tissue where the resection is performed. Motor function was assessed one day after surgery, at discharge, and at 3 months. Results: All procedures were technically successful. There was a 1:1 correlation of motor thresholds (MTs) for stimulation sites simultaneously mapped with the new suction mapping device and the classic fingerstick probe (24 patients, 74 stimulation points, r=0.996, p<0.001). Lowest individual MTs
Abstracts of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339
Results: Intraoperative VEP monitoring was feasible in 27 patients (82%) and not feasible in 6 patients with severe preoperative visual dysfunction. N75 had median amplitude 2.6μV (range 0.8-7.7μV) and latency 84ms (57142ms). P100 had medianamplitude 2.0μV (0.5-7.0μV) and latency 102ms (75-161ms). N75 amplitude differed significantly between patients with preoperative normal and impaired visual function (P <0.05). Of all recording channels, Oz/A+ provided the largestnumber of stable VEPs (36/51, 71%). Of the 23 patients without N75 amplitude loss, 2 showed improved visual function postoperatively, 18 showed no change and 3 developed hemianopsia. This resulted in a specificity of 96% and a negative predictive value of 89%. Temporary VEP loss was observed in 3 patients and visual function was preserved. Permanent VEP loss was seen in 1patient without new postoperative visual impairment. Conclusions: Intraoperative VEP monitoring was feasible in all patients with intact preoperative visual function. Minor visual field defects such as quadrantanopsia did not affect VEP monitoring. Feasibility of intraoperative VEP monitoring depended strongly on the integrity of visual function. Patient selection should consider visual function.
P163 Intraoperative monitoring of cranial nerves function in surgery of skull base tumours M. Hupalo, D.J. Jaskolski Barlicki Univeristy Hospital, Neurosurgery, Lodz, Poland Question: Developing technique of mapping of cranial nerves (III, IV, VI, VII, IX - XII) along with their continuous intraoperative monitoring in surgery of skull base tumours and assessement of utility of this technique in clinical practice. Material and methods: There were 16 patients (12 females and 4 men, mean age 50 years) with giant tumours of skull base (meningiomas: 5 petroclival, 2 of cavernous sinus, 1 of foramen magnum, 2 of petrous bone, 1 epidermoid in cerebello-pontine angle and in cavernous sinus, 2 chemodectomas, schwannomas: one of the IX nerve and one of the V nerve, inflammatory tumour in infratemporal fossa, ethmoid cells and sphenoid sinus. All the cases were operated on with mapping and monitoring of the cranial nerves: III nerve – 8 cases, IV – 11, VI – 11, VII – 12, IX – 8, X – 8, XI – 7 and XII – 4. The nerves were identified by means of nerve conduction velocity (NCV) and monitored with free run EMG recorded from muscles innervated by respective cranial nerves. Characteristic changes in recording and warning sounds heralded an imminent nerve damage thus providing warning to a surgeon. Results: The mapping was successful in 15 patients. The failure happened in a giant petrous bone meningioma in which the monitoring of oculomotor nerves (III, IV, VI) and and facial nerve was attempted. Long-lasting and frequent irritation of a nerve, despite preservation of its anatomical integirity, resulted in the adequate neurological deficit present for up to a few months after surgery. Particularly, facial nerve was often affected in such a way. On the other hand, adbucens nerve palsy occurring despite its identification turned out to be the most frequently encountered adverse event. Conclusions: Intraoperative neurophysiological mapping of the oculomotor nerves (III, IV, VI), facial nerve and lower cranial nerves is possible in almost all patients with skull base tumours. In majority of cases an early warning allows sparing of the affected nerve.
P164 Intraoperative neurophysiologic monitoring of surgical and endovascular treatment of pediatric arteriovenous malformations V. Nguyen, S. Avila, S. Cho, L. Lee, S. Le, J. López Stanford University, School of Medicine, Department of Neurology, Stanford, United States Objective: To analyze how intraoperative neurophysiologic monitoring (IONM) changes correlate with new postoperative deficits in the surgical and endovascular treatment of pediatric arteriovenous malformations (AVMs). Background: IONM aids in identifying neurological compromise during procedures that place the nervous system at risk. Cerebral AVMs are vascular anomalies that pose a risk for hemorrhage, stroke, or seizures. The utility of IONM in the treatment of pediatric AVMs has not been well documented. Design/methods: 320 cases in 147 patients ages 10 days to 18 years were examined, including 213 endovascular embolizations and 107 surgi-
cal resections, all monitored with EEG, SSEPs, MEPs, EMG, and/or BAEPs. Preoperative and postoperative neurological deficits were analyzed using electronic medical records. IONM changes were defined as being either transient (resolving by the end of monitoring) or persistent (not resolving). Results: 43 (13.4%) cases had IONM changes, 14 were persistent, and of those, 9 (64.2%) had post-operative deficits. 29 changes were transient, but only 6 (20.7%) of those had post-operative deficits. 277 (86.6%) cases lacked IONM changes, 6 (2.2%) of these had new deficits associated with cerebral hypoperfusion or edema after the end of monitoring, and 7 (2.5%) developed new deficits outside of the neurologic territory monitored. 28 (8.8%) cases presented IONM changes but did not have post-operative deficits; most of these were associated with alterations in surgical management or pre-embolization methohexital testing (performed to prevent permanent neurological injury). Conclusions: Persistent IONM changes had a strong correlation with new post-operative deficits. Transient IONM changes, including those resolving after alterations in surgical management or pre-embolization methohexital testing, had a much lower risk of new deficits. Therefore, IONM can be a useful tool in pediatric AVM cases, not only in predicting neurological compromise, but also in identifying when to alter management.
P165 Spinal intradural tumours: a single centre experience L. Cabañes Martínez 1 , I. Regidor 1 , G. de Blas 1 , F. Abreu 2 , R. Carrasco 2 , M. del Álamo 2 , L. Ley 2 1 Hospital Ramón y Cajal, Clinical Neurophysiology, Madrid, Spain; 2 Hospital Ramón y Cajal, Neurosurgery, Madrid, Spain Question: Primary spinal cord tumours represent 2% to 4% of all central nervous system neoplasms and are anatomically separable into two broad categories: intradural intramedullary and intradural extramedullary. We present our experience treating this kind of tumours in the last 10 years, with an especial focus on the use of intraoperative neurophysiologic monitoring (IOM). Methods: We have performed a retrospective study within our institution, from an epidemiologic, clinical, radiologic and surgical point of view, including the use of IOM. Results: A total of 93 patients, ages between 22 and 81 years old. The most frequent clinical presentation was motor deficit and pain. There was great histological variation, but neurinomas, meningiomas and ependymomas were more frequent. Multimodal IOM was used in 41% of the cases. We observed that in the group of monitorized patients the rate of neurological sequelae was lower that in the non-monitorized group. Conclusions: The use of IOM in primary intradural spinal cord tumours reduces the incidence of neurological complications. IOM can identify neurological injury with excellent sensitivity.
P166 Continuous dynamic mapping of the corticospinal tract during surgery of motor eloquent brain tumors K. Seidel, J. Beck, P. Schucht, A. Raabe Inselspital University Hospital Bern, Neurosurgery, Bern, Switzerland Question: We developed a new mapping protocol to overcome the temporal and spatial limitations of classical subcortical mapping of the corticospinal tract (CST). The feasibility and safety of continuous (0.4-2 Hz) and dynamic (at the site of and synchronized with tissue resection) subcortical motor mapping was evaluated. Methods: We prospectively studied 128 patients who underwent tumor surgery adjacent to the CST (<1 cm using diffusion tension imaging (DTI) and fiber tracking) with simultaneous subcortical monopolar motor mapping (short train, inter-stimulus interval (ISI) 4.0 ms, pulse duration 500 μs) and a new acoustic motor evoked potential (MEP)-alarm. Continuous (temporal coverage) and dynamic (spatial coverage) mapping was technically realized by integrating the mapping probe at the tip of a new suction device with the concept that this device will be in contact with the tissue where the resection is performed. Motor function was assessed one day after surgery, at discharge, and at 3 months. Results: All procedures were technically successful. There was a 1:1 correlation of motor thresholds (MTs) for stimulation sites simultaneously mapped with the new suction mapping device and the classic fingerstick probe (24 patients, 74 stimulation points, r=0.996, p<0.001). Lowest individual MTs