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P11.9 Diagnostic yield of the electroencephalograph on a general adult intensive treatment unit
S112 implantation procedure is performed under local anaesthesia with intraoperative neurophysiological monitoring (microelectrode recording and micro or macrostimulation) for the optimal targeting and for the evaluation of stimulation-induced clinical or adverse effects. Objectives: To evaluate the feasibility of microelectrode recording for deep brain stimulation surgery in parkinsonian patients under general anaesthesia using a specific ketamine-based anaesthetic protocol and to compare the neurophysiological data obtained under these conditions with those ones obtained in the same patients previously underwent to surgery under local anaesthesia. Methods: 5 patients affected by advanced Parkinson’s disease underwent to bilateral subthalamic nucleus stimulation at first under local anaesthesia and then, owing some surgical device complications, under general anaesthesia with a total intravenous protocol based on remifentanyl and ketamine infusion. Neurophysiological data obtained under local and general anaesthesia were then analysed and compared with an off-line spike sorting software (FSPS-University of Ferrara) and a statistical analysis. Results: For all the neurophysiological parameters analysed, we didn’t find any statistical significative difference between the first and second surgical procedure. Conclusions: Subthalamic nucleus stimulation for advanced Parkinson’s disease with microelectrode recording guidance is possible and reliable under a ketamine-based general anaesthesia. So, even if awake surgery represents the “gold standard” for functional neurosurgery, general anaesthesia can be an alternative for those patients who don’t accept awake surgery because of clinical reasons, such as massive fear, reduced cooperativity, or severe “off”-medication effects. P11.8 Direct muscle stimulation versus composed motor action potential (CMAP) duration for the diagnosis of critical illness “neuromyopathy”: evaluation of sensitivity and specificity R. Carrai1 , F. Melani1 , F. Fiesoli1 , L. Caremani1 , S. Fossi1 , A. Comanducci1 , C. Martinelli1 , S. Lori1 , F. Pinto1 , A. Grippo1 , A. Amantini1 1 Neurofisiopatologia, DAI Neuroscienze, AOU Careggi, Florence, Italy Objective: Critical illness neuromyopathy (CRIMYNE) is the most common cause of acquired diffuse weakness in Intensive Care Units. Clinical examination and conventional electrodiagnostic techniques may not distinguish between critical illness polyneuropathy or myopathy. We assess the value of direct muscle stimulation (DMS) for diagnosis of myopathic involvement in CRIMYNE. Methods: 44 consecutive patients (19 women, 15 men, aged from 23 to 81 years) with acquired diffuse motor weakness were studied in ICU with standard ENG/EMG exam. DMS was recorded from tibial anterior (TA) muscle with bipolar recording (anode and cathode placed respectively on muscle belly and tendon) using subdermal needles after monopolar stimulation in the distal third of the muscle away from the motor point. We also measured the duration of TA and Abductor Digiti Minimi (ADM) CMAPs considering both the duration of negative phase and total duration. Results: CRYMNE was confirmed on 39/44 cases, 18 with only motor involvement, 21 with combined motor and sensory involvement. Amplitude of CMAPs was abnormal in 100% (from 10% to 45% compared to age matched control values). DMS was obtained in 26 cases. Median value of neCMAP/dmCMAP ratio resulted 1.2 with IQR = 0.6; mean dmCMAP 5º percentile of normal value). amplitude was 2.5±2.1 mV (8.8 mV All patients showed markedly increased CMAP duration, both of negative phase (TA 16.69±5.58 ms; ADM 10.65±4.62 ms) and total duration (TA 44.75±16.80 ms; ADM 33.08±11.36 ms). Conclusion: Our findings of prolonged CMAP duration with synchronized dispersion, in association with reduced dmCMAP amplitude obtained with DMS agree and support the hypothesis of reduced muscle membrane excitability. All these parameters have an high specificity for diagnosis of myopathic involvement in CRIMYNE but sensitivity was greater for CMAP duration.
Poster presentations: Poster session 11. Neuromonitoring
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P11.9 Diagnostic yield of the electroencephalograph on a general adult intensive treatment unit R. MacDonagh1 , R. Hughes2 Department of Neurophysiology, Central Manchester University Hospitals, Manchester, United Kingdom, 2 Department of Clinical Neurophysiology, Central Manchester University Hospitals, Manchester, United Kingdom 1
Introduction: Electroencephalography (EEG) is a rapid and safe test, which assesses the thalamocortical function in comatose and other patients on the intensive treatment unit. However EEG patterns can be non-specific and their interpretation can be hampered by artefacts and the effects of sedation. Objectives: To determine the diagnostic yield of EEG recordings on the Intensive Treatment Unit (ITU) and the influence of sedative medication. Methods: Prospective review of 104 EEG recordings on an adult ITU performed between 2008 and 2010. Information gathered about clinical indication, medications (particularly sedative), if sedative medication was indicated on the referral and diagnostic EEG features. EEG findings were classified as encephalopathy, status epilepticus, isoelectric, normal and those with significant interpretational difficulties. Results: Encephalopathy was the most common EEG indication (63%) followed by ?sub-clinical seizure activity (36%). 35% of patients were on sedation. 22% had interpretation difficulties due to sedation. 36% had sedation indicated on the referral. Of the patients on sedative medication, 64% had EEGs that were difficult to interpret due to the effects of sedation. 4% of all EEGs showed sub-clinical seizure activity. Of all the EEG’s that were ?sub-clinical seizure activity 8% were reported as this. Of patients referred with ?sub-clinical seizure activity, 68% had an encephalopathic EEG and one EEG (1%) was normal. Conclusion: Encephalopathy was the major indication for an EEG. There was a low incidence of sub-clinical seizure activity and one definite clinical seizure with EEG correlate. There is a significant minority of records with interpretation difficulties due to the effects of sedation. The diagnostic yield is high (78%). Yield may be improved by investigations appropriately timed relative to the timing of sedative medication. Several key questions still remain including, can we be more specific in the aetiology of encephalopathy findings and can we reduce the number of EEG’s with sedation effects by timing the EEG more appropriately. P11.10 Impact of intraoperative D wave recording in spine surgery P. Costa1 , A. Borio1 , M. Giacobbi1 , G. Isoardo1 , P. Ciaramitaro1 , C. J¨ unemann1 , P. Pacca1 , S. Marmolino1 , G. Faccani2 1 Section of Clinical Neurophysiology, CTO Hospital, Turin, Italy, 2 Neurosurgery, CTO Hospital, Turin, Italy Introduction: Combined recordings of epidural- (D wave) and muscle motor evoked potentials (m-MEPs) has been proposed in many studies in intramedullary spinal cord tumors (IMSCT) surgery, although not all agree. Furthermore it’s unclear the usefulness of intraoperative monitoring of motor systems by using both methods in other types of spine surgery, particularly in compromised patients, in whom the multipulse technique can fail to evoke m-MEPs in target muscles. Objectives: To test the impact of intraoperative D wave on monitorability and motor outcome in spine surgery. Methods. Intraoperative recording of transcranially elicited lower limb m-MEPs (LL m-MEPs) and epidurally recorded D wave caudally to the surgical level was attempted in 103 spine and spinal cord surgeries (23 IMSCT, 55 extramedullary spinal cord tumors and 25 myelopathies). Results: The overall monitorability was 97.1%, being at least one of the three modality applicable in 100 surgeries. Baseline LL m-MEPs were recorded bilaterally in 85 surgeries and unilaterally in 11: therefore m-MEP responses at baseline from at least 1 target muscle were detectable in 96 procedures. A clear caudal D wave was recorded in 97 surgeries. No intraoperative changes were observed in 79/100 of the procedures and none of these subjects had postoperative deficits. Transient or persistent intraoperative modifications occurred in 14/23 of IMSCT, 5/55 of extramedullary spinal cord tumors and 2/25 myelopathies. A persistent stable caudal D wave correctly predicted a good motor outcome even in case of LL-MEPs absent or lost during surgery. Conclusions: Intraoperative D wave recording has to be considered mandatory in IMSCT surgery and should be attempted in other types of spine and spinal cord surgeries, particularly in compromised patients with absent or poorly defined LL m-MEPs.
Poster presentations: Poster session 11. Neuromonitoring
1
P11.9 Diagnostic yield of the electroencephalograph on a general adult intensive treatment unit R. MacDonagh1 , R. Hughes2 Department of Neurophysiology, Central Manchester University Hospitals, Manchester, United Kingdom, 2 Department of Clinical Neurophysiology, Central Manchester University Hospitals, Manchester, United Kingdom 1
Introduction: Electroencephalography (EEG) is a rapid and safe test, which assesses the thalamocortical function in comatose and other patients on the intensive treatment unit. However EEG patterns can be non-specific and their interpretation can be hampered by artefacts and the effects of sedation. Objectives: To determine the diagnostic yield of EEG recordings on the Intensive Treatment Unit (ITU) and the influence of sedative medication. Methods: Prospective review of 104 EEG recordings on an adult ITU performed between 2008 and 2010. Information gathered about clinical indication, medications (particularly sedative), if sedative medication was indicated on the referral and diagnostic EEG features. EEG findings were classified as encephalopathy, status epilepticus, isoelectric, normal and those with significant interpretational difficulties. Results: Encephalopathy was the most common EEG indication (63%) followed by ?sub-clinical seizure activity (36%). 35% of patients were on sedation. 22% had interpretation difficulties due to sedation. 36% had sedation indicated on the referral. Of the patients on sedative medication, 64% had EEGs that were difficult to interpret due to the effects of sedation. 4% of all EEGs showed sub-clinical seizure activity. Of all the EEG’s that were ?sub-clinical seizure activity 8% were reported as this. Of patients referred with ?sub-clinical seizure activity, 68% had an encephalopathic EEG and one EEG (1%) was normal. Conclusion: Encephalopathy was the major indication for an EEG. There was a low incidence of sub-clinical seizure activity and one definite clinical seizure with EEG correlate. There is a significant minority of records with interpretation difficulties due to the effects of sedation. The diagnostic yield is high (78%). Yield may be improved by investigations appropriately timed relative to the timing of sedative medication. Several key questions still remain including, can we be more specific in the aetiology of encephalopathy findings and can we reduce the number of EEG’s with sedation effects by timing the EEG more appropriately. P11.10 Impact of intraoperative D wave recording in spine surgery P. Costa1 , A. Borio1 , M. Giacobbi1 , G. Isoardo1 , P. Ciaramitaro1 , C. J¨ unemann1 , P. Pacca1 , S. Marmolino1 , G. Faccani2 1 Section of Clinical Neurophysiology, CTO Hospital, Turin, Italy, 2 Neurosurgery, CTO Hospital, Turin, Italy Introduction: Combined recordings of epidural- (D wave) and muscle motor evoked potentials (m-MEPs) has been proposed in many studies in intramedullary spinal cord tumors (IMSCT) surgery, although not all agree. Furthermore it’s unclear the usefulness of intraoperative monitoring of motor systems by using both methods in other types of spine surgery, particularly in compromised patients, in whom the multipulse technique can fail to evoke m-MEPs in target muscles. Objectives: To test the impact of intraoperative D wave on monitorability and motor outcome in spine surgery. Methods. Intraoperative recording of transcranially elicited lower limb m-MEPs (LL m-MEPs) and epidurally recorded D wave caudally to the surgical level was attempted in 103 spine and spinal cord surgeries (23 IMSCT, 55 extramedullary spinal cord tumors and 25 myelopathies). Results: The overall monitorability was 97.1%, being at least one of the three modality applicable in 100 surgeries. Baseline LL m-MEPs were recorded bilaterally in 85 surgeries and unilaterally in 11: therefore m-MEP responses at baseline from at least 1 target muscle were detectable in 96 procedures. A clear caudal D wave was recorded in 97 surgeries. No intraoperative changes were observed in 79/100 of the procedures and none of these subjects had postoperative deficits. Transient or persistent intraoperative modifications occurred in 14/23 of IMSCT, 5/55 of extramedullary spinal cord tumors and 2/25 myelopathies. A persistent stable caudal D wave correctly predicted a good motor outcome even in case of LL-MEPs absent or lost during surgery. Conclusions: Intraoperative D wave recording has to be considered mandatory in IMSCT surgery and should be attempted in other types of spine and spinal cord surgeries, particularly in compromised patients with absent or poorly defined LL m-MEPs.