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P251 Surgery of intrinsic brainstem tumors: Electrophysiological monitoring of cranial motor nuclei III–XII
Poster Session: Intraoperative and Intensive Care Monitoring Procedures
330
train of stimuli was applied to the sole of one foot 60-100 ms before the cortical stimulus. With this technique, MEPs of sufficient amplitude for monitoring were recorded in 23 patients. In many of these patients, cortical stimulation alone was not sufficient to produce an MEP. The remaining three patients, in which no or unreliable responses were recorded, suffered from para- or tetraparesis before the operation. The results suggest that this method is adequate for spinal cord monitoring in neurologically intact patients. Thus, invasive methods with epidural electrodes in the spinal canal can be avoided.
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SURGERY OF INTRINSIC BRAINSTEM TUMORS: ELECTROPHYSIOLOGICAL MONITORING OF CRANIAL MOTOR NUCLEI III-XII
W. Eisner, U,D. Schmid, C. Gall, H.J. Reulen. Department of
Neurosurgery, LMU Munich, German 3, Introduction: Operations next to or within the brainstem carry a significant risk of postoperative motor cranial nerve deficits. We wanted to test whether the motor nuclei III-XII and their intrapontine nerve segments can be located using neurographical techniques, and whether continuous recording of EMG-activity is capable of guiding the surgeon during dissection of the tumor near these highly vulnerable structures. Material and Methods: 14 patients were operated for tumors near the floor of the fourth ventricle. Needle recordings were made from the muscles supplied by the cranial nerves III-XII. Monitoring consisted 1) of mapping using motor nucleus neurography of the rhomboid fossa, and 2) of continuous functional control by recording EMG-activity during tumor dissection. Results: In 12 (2) cases, the lesions were removed radically (subtotally). Postoperatively 9 (64%) patients had some transient deterioration in motor cranial nerve function, 4 (29%) patients had no change in their neurological examination, 1 patient showed an improved neurostatus in comparison to the preoperative symptoms. Discussion: Based on the anatomical and mapping data, a safe route of access to the lesion could be chosen. Dissection near motor nuclei could reliably be guided on the basis of continuous EMG-recording that warned the surgeon as soon manipulations elicited transient EMG-discharges in the pertinent muscles.
-~ IMPROVEMENT OF HEARING AND FACIAL NERVE FUNCTION IN ACOUSTIC NEUROMA SURGERY USING INTRAOPERATIVE NEUROPHYSlOLOGIC MONITORING R.H. Goidbrunner, H.-P. Schlake, M. Janka, J. Helms i, K. Roosen. Dept.
of Neurosurgery, Univ. of Wiirzburg, D-97080 Wii~burg, Germany; t Dept. of ENTSurgery, Univ. of Wiirzburg, D-97080 Wiirzburg. German 3" Intraoperative EMG monitoring of facial nerve function and AEP monitoring of hearing function are widely used in acoustic neuroma surgery. It was the purpose of the present study to evaluate the efficacy of these methods in short and long term follow-up. Patients and Methods: Two groups of each 50 patients operated on intra/extrameatal acoustic neuromas were evaluated retrospectively. Both groups (A: without/B: with monitoring) were compared concerning outcome of facial nerve and hearing function 1 week and 6 months after surgery. For classification of facial nerve function a modified House-Brackmann-Score (liB) was used; hearing function (PTA) was evaluated using the Gardner-
Robertson-Scale (GR). Results: No differences regarding age, sex and tumor size were obtained between both groups. In patients with intraoperative EMG monitoring facial nerve function could be preserved in a significant higher number of cases (p < 0.005). Only one patient suffered from facial plegia (HB = 6) after 6 months (group A: 14%), 10% had severe paresis (HB = 4/5, A: 16%), 24% mild paresis (HB --- 2/3, A: 26%). There was no paresis in 64% of all patients (A: 44%). In group B significantly more patients (34%) revealed hearing preservation (GR = 1-3) when compared to group A (14%, p < O.O5). Conclusion." Intraoperative facial and cochlear nerve monitoring are reliable and easy practicable methods, which improve long term outcome significantly. Thus, intraoperative neurophysiologic monitoring proves to be useful in acoustic neuroma surgery.
INTRAOPERATIVE MONITORING OF THE INFERIOR ALVEOLAR NERVE S.K. Ja~iskelainen, J.K. Pehola. Dept of Clinical Neurophysiology,
University Central Hospital, Turku, Finland We recorded sensory action potentials (SAP) of the inferior alveolar nerve (IAN) during mandibular sagittal split osteotomy (SSO). The objectives of the study were to determine at which stage of the SSO the IAN injury occurs and to develope an intraoperative monitoring technique to prevent nerve damage. Bilateral recordings were made in six patients with active wire electrodes at the oval foramen. Silver chloride surface electrodes were used as reference. Stimulation was at the mental foramen with two monopolar needle electrodes that were attached with cold acrylate to dental splint. On each side, the SAPs were elicited with electrical stimuli (0.2 ms, 3-5 mA) throughout the operation at intervals of 15 to 60 seconds. The SAPs disappeared during medial retraction that lasted from 7 to 20 minutes. After short retraction times (< 10 min), the SAPs reappeared during the following 20 minutes with prolonged latencies and diminished amplitudes. Splitting of the mandible caused additional nerve damage. A modification of the operation technique during medial approach enabled continous recording of the SAPs of the IAN throughout the operation in the last two patients.
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DIAGNOSIS AND PROGNOSIS OF PATIENTS IN COMA WITH A VASCULAR AND ANOXIC ORIGIN
P. Chaparro-Hernfindez, J. Madrazo, J.E. Ortega, E. Montes, E Murillo.
H. U. V. del Rocfo, Sevilla, Spain Objective: Early lesional diagnosis and prognosis of patients in coma with an anoxic or vascular origin. Methods: We have studied 64 patients in coma of a vascular (33) and ano×ic (31) etiology, with a GCS < 7, within the first 5 days of their evolution, by means of EEG, SEPs and BSEPs. Four different neurophysiological levels of lesion (cortical, subcortical, mesencephalic and bulbar) have been stated, being related to the outcome of the patient (GOS). Results: We have found a good correlation between the cortical level of lesion and a good outcome (p < 0.0003) and between the meseneephalic and butbar levels with a poor outcome (p < 10-6). EEG reactivity has proven a sign of good outcome (p < 0.00001). We have not detected differences between the etiology of coma and the final outcome. Conclusions: The Neurophysiological examination is shown as a fast, efficient, bedside and non-invasive procedure for the diagnosis and prognosis of the comatose patients. The best time for its obtention is after the first 24 hours.
PROGNOSTIC EVALUATION OF PATIENTS WITH SEVERE HEAD INJURY BY MULTIMODAL EVOKED POTENTIALS S. Djuric, Z. Milenkovic, J. Stamenovic, M. Jolic. Clinic of Neurology,
Clinical Center, Nis, Yugoslavia Prognostic evaluation of severe head injury was performed in 60 patients by visual evoked potentials (VEP's), somatosensory evoked potentials (SEP's) and brain stem auditory evoked potentials (BAEP's) in relation to duration of coma level and the outcome. The Innsbruck Coma Scale (ICS) for the evaluation of the coma level and the Glasgow Outcome Scale (GOS) for the outcome were used. MEP's were recorded within 3 days, 1, 3, 6 months after the injury. The outcome of patients 1, 3 and 6 months after the injury was correlated with results of MEP's. MEP's show different correlation and sensitivity in relation to the duration of coma level and outcome. SEP's and BAEP's had the best correlation and the greatest sensitivity, while VEP's had the lowest degree of sensitivity. There was a good correlation between SEP's, BAEP's and ICS I month after the injury. As well, there was a closer correlation between SEP's, BAEP's and GOS, 3 and 6 months after the injury. In conclusion, use of MEP's is useful in prognosis of acute head injury though MEP's have different correlation with ICS and GOS, and different diagnostic sensitivity.
330
train of stimuli was applied to the sole of one foot 60-100 ms before the cortical stimulus. With this technique, MEPs of sufficient amplitude for monitoring were recorded in 23 patients. In many of these patients, cortical stimulation alone was not sufficient to produce an MEP. The remaining three patients, in which no or unreliable responses were recorded, suffered from para- or tetraparesis before the operation. The results suggest that this method is adequate for spinal cord monitoring in neurologically intact patients. Thus, invasive methods with epidural electrodes in the spinal canal can be avoided.
~-~
SURGERY OF INTRINSIC BRAINSTEM TUMORS: ELECTROPHYSIOLOGICAL MONITORING OF CRANIAL MOTOR NUCLEI III-XII
W. Eisner, U,D. Schmid, C. Gall, H.J. Reulen. Department of
Neurosurgery, LMU Munich, German 3, Introduction: Operations next to or within the brainstem carry a significant risk of postoperative motor cranial nerve deficits. We wanted to test whether the motor nuclei III-XII and their intrapontine nerve segments can be located using neurographical techniques, and whether continuous recording of EMG-activity is capable of guiding the surgeon during dissection of the tumor near these highly vulnerable structures. Material and Methods: 14 patients were operated for tumors near the floor of the fourth ventricle. Needle recordings were made from the muscles supplied by the cranial nerves III-XII. Monitoring consisted 1) of mapping using motor nucleus neurography of the rhomboid fossa, and 2) of continuous functional control by recording EMG-activity during tumor dissection. Results: In 12 (2) cases, the lesions were removed radically (subtotally). Postoperatively 9 (64%) patients had some transient deterioration in motor cranial nerve function, 4 (29%) patients had no change in their neurological examination, 1 patient showed an improved neurostatus in comparison to the preoperative symptoms. Discussion: Based on the anatomical and mapping data, a safe route of access to the lesion could be chosen. Dissection near motor nuclei could reliably be guided on the basis of continuous EMG-recording that warned the surgeon as soon manipulations elicited transient EMG-discharges in the pertinent muscles.
-~ IMPROVEMENT OF HEARING AND FACIAL NERVE FUNCTION IN ACOUSTIC NEUROMA SURGERY USING INTRAOPERATIVE NEUROPHYSlOLOGIC MONITORING R.H. Goidbrunner, H.-P. Schlake, M. Janka, J. Helms i, K. Roosen. Dept.
of Neurosurgery, Univ. of Wiirzburg, D-97080 Wii~burg, Germany; t Dept. of ENTSurgery, Univ. of Wiirzburg, D-97080 Wiirzburg. German 3" Intraoperative EMG monitoring of facial nerve function and AEP monitoring of hearing function are widely used in acoustic neuroma surgery. It was the purpose of the present study to evaluate the efficacy of these methods in short and long term follow-up. Patients and Methods: Two groups of each 50 patients operated on intra/extrameatal acoustic neuromas were evaluated retrospectively. Both groups (A: without/B: with monitoring) were compared concerning outcome of facial nerve and hearing function 1 week and 6 months after surgery. For classification of facial nerve function a modified House-Brackmann-Score (liB) was used; hearing function (PTA) was evaluated using the Gardner-
Robertson-Scale (GR). Results: No differences regarding age, sex and tumor size were obtained between both groups. In patients with intraoperative EMG monitoring facial nerve function could be preserved in a significant higher number of cases (p < 0.005). Only one patient suffered from facial plegia (HB = 6) after 6 months (group A: 14%), 10% had severe paresis (HB = 4/5, A: 16%), 24% mild paresis (HB --- 2/3, A: 26%). There was no paresis in 64% of all patients (A: 44%). In group B significantly more patients (34%) revealed hearing preservation (GR = 1-3) when compared to group A (14%, p < O.O5). Conclusion." Intraoperative facial and cochlear nerve monitoring are reliable and easy practicable methods, which improve long term outcome significantly. Thus, intraoperative neurophysiologic monitoring proves to be useful in acoustic neuroma surgery.
INTRAOPERATIVE MONITORING OF THE INFERIOR ALVEOLAR NERVE S.K. Ja~iskelainen, J.K. Pehola. Dept of Clinical Neurophysiology,
University Central Hospital, Turku, Finland We recorded sensory action potentials (SAP) of the inferior alveolar nerve (IAN) during mandibular sagittal split osteotomy (SSO). The objectives of the study were to determine at which stage of the SSO the IAN injury occurs and to develope an intraoperative monitoring technique to prevent nerve damage. Bilateral recordings were made in six patients with active wire electrodes at the oval foramen. Silver chloride surface electrodes were used as reference. Stimulation was at the mental foramen with two monopolar needle electrodes that were attached with cold acrylate to dental splint. On each side, the SAPs were elicited with electrical stimuli (0.2 ms, 3-5 mA) throughout the operation at intervals of 15 to 60 seconds. The SAPs disappeared during medial retraction that lasted from 7 to 20 minutes. After short retraction times (< 10 min), the SAPs reappeared during the following 20 minutes with prolonged latencies and diminished amplitudes. Splitting of the mandible caused additional nerve damage. A modification of the operation technique during medial approach enabled continous recording of the SAPs of the IAN throughout the operation in the last two patients.
~-~
DIAGNOSIS AND PROGNOSIS OF PATIENTS IN COMA WITH A VASCULAR AND ANOXIC ORIGIN
P. Chaparro-Hernfindez, J. Madrazo, J.E. Ortega, E. Montes, E Murillo.
H. U. V. del Rocfo, Sevilla, Spain Objective: Early lesional diagnosis and prognosis of patients in coma with an anoxic or vascular origin. Methods: We have studied 64 patients in coma of a vascular (33) and ano×ic (31) etiology, with a GCS < 7, within the first 5 days of their evolution, by means of EEG, SEPs and BSEPs. Four different neurophysiological levels of lesion (cortical, subcortical, mesencephalic and bulbar) have been stated, being related to the outcome of the patient (GOS). Results: We have found a good correlation between the cortical level of lesion and a good outcome (p < 0.0003) and between the meseneephalic and butbar levels with a poor outcome (p < 10-6). EEG reactivity has proven a sign of good outcome (p < 0.00001). We have not detected differences between the etiology of coma and the final outcome. Conclusions: The Neurophysiological examination is shown as a fast, efficient, bedside and non-invasive procedure for the diagnosis and prognosis of the comatose patients. The best time for its obtention is after the first 24 hours.
PROGNOSTIC EVALUATION OF PATIENTS WITH SEVERE HEAD INJURY BY MULTIMODAL EVOKED POTENTIALS S. Djuric, Z. Milenkovic, J. Stamenovic, M. Jolic. Clinic of Neurology,
Clinical Center, Nis, Yugoslavia Prognostic evaluation of severe head injury was performed in 60 patients by visual evoked potentials (VEP's), somatosensory evoked potentials (SEP's) and brain stem auditory evoked potentials (BAEP's) in relation to duration of coma level and the outcome. The Innsbruck Coma Scale (ICS) for the evaluation of the coma level and the Glasgow Outcome Scale (GOS) for the outcome were used. MEP's were recorded within 3 days, 1, 3, 6 months after the injury. The outcome of patients 1, 3 and 6 months after the injury was correlated with results of MEP's. MEP's show different correlation and sensitivity in relation to the duration of coma level and outcome. SEP's and BAEP's had the best correlation and the greatest sensitivity, while VEP's had the lowest degree of sensitivity. There was a good correlation between SEP's, BAEP's and ICS I month after the injury. As well, there was a closer correlation between SEP's, BAEP's and GOS, 3 and 6 months after the injury. In conclusion, use of MEP's is useful in prognosis of acute head injury though MEP's have different correlation with ICS and GOS, and different diagnostic sensitivity.