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At least 19 recordsLinked to original sources

[Somatosensory evoked potentials and electromyography in spinal cord intraoperative monitoring].

Intraoperative monitoring can be defined as an application of several electroneurophysiological techniques for nervous system monitoring throughout the surgery. The principal goal of monitoring is to identify new neurologic impairment early enough to find the cause and to prevent permanent deficits. This paper reviews monitoring techniques during surgery for spinal deformity.

Electroencephalography↗

[Experimental and clinical study on intraoperative monitoring of facial nerve].

OBJECTIVE: The aim of the study is to determine parameters that be predictive of function of facial nerve after facial nerve decompression surgery. METHOD: Fifteen New Zealand white rabbits (30 facial nerves) and 21 patients with peripheral facial paralysis were monitored intraoperatively during facial nerve decompression surgery. These patients were followed up for at least 6 months. RESULT: Threshold of EMG is a steady parameter of assessing the function of facial nerve. The threshold between different segments of facial nerve has no difference in New Zealand white rabbits. That there exist EMG events were correlated significantly with good postoperative facial nerve function. CONCLUSION: Threshold of EMG can be used as objective and steady parameter that assess the function of facial nerve. Intraoperative monitoring events can be used for assessment of postoperative facial nerve function.

Adolescent↗

Intraoperative monitoring of danaparoid sodium anticoagulation during cardiovascular operations.

PURPOSE: Patients with cardiovascular disorders frequently need anticoagulation for diagnostic studies, surgical procedures, and therapy. Heparin-induced thrombocytopenia is a relatively common complication of heparin therapy that can result in thrombosis and subsequent limb loss or death, necessitating use of alternative anticoagulants. METHODS: Two patients who needed cardiac surgery had thrombocytopenia induced by exposure to heparin and heparin-coated tubing. Several assays were examined for their ability to monitor intraoperative anticoagulation of a factor Xa inhibitor, danaparoid sodium. RESULTS: In vitro, celite and kaolin activated dotting times and activated partial thromboplastin time were prolonged linearly in the presence of increasing concentrations of danaparoid sodium. Aprotinin did not alter the linearity of the response but did alter its slope. In vivo, activated clotting times and activated partial thromboplastin time were insensitive to clinically significant changes in danaparoid sodium plasma levels during cardiopulmonary bypass. Correction in activated partial thromboplastin time lagged 2 hours behind clinically important changes in anti-factor Xa levels. Only anti-factor Xa levels were adequate to monitor intraoperative danaparoid sodium levels. CONCLUSION: Anticoagulation for cardiopulmonary bypass can be successfully performed with danaparoid sodium and intraoperative anti-factor Xa monitoring.

Adult↗

A quantitative assessment of the brain stem auditory evoked response during intraoperative monitoring.

The brain stem auditory evoked response (BAER) was monitored intraoperatively in 11 patients with tumors of the posterior fossa. A technique for the objective quantitative assessment of the BAER based on the variance of the phase angle between small group averages is described. The resulting component synchrony measure corroborated standard peak latency and amplitude changes of the BAER during operative manipulation. A discussion of the replication and use of the objective measure is presented.

Brain Stem↗

Does intraoperative monitoring of auditory evoked potentials reduce incidence of hearing loss as a complication of microvascular decompression of cranial nerves?

During a 14-month period, 129 individuals underwent 140 operations for microvascular decompression to relieve hemifacial spasm, disabling positional vertigo, tinnitus, or trigeminal neuralgia at our institution. Seven patients were operated upon twice on the same side and 4 were operated upon on both sides at different times. In each case, the brainstem auditory evoked potentials were monitored intraoperatively by the same neurophysiologist. In 75 of these operations, compound action potentials were also recorded from the exposed 8th nerve. Comparison of speech discrimination scores before the operation and at the time of discharge showed that at discharge, discrimination had decreased in 7 patients by 15% or more and increased in 4 patients by 15% or more, in 2 patients by as much as 52%. Essentially similar results were obtained when preoperative speech discrimination scores were compared with results obtained from the 87 patients who returned for a follow-up visit between 3 and 6 months after discharge. Only one patient lost hearing (during a second operation to relieve hemifacial spasm). Another patient (also operated upon to relieve hemifacial spasm) suffered noticeable hearing loss postoperatively, but had recovered nearly normal hearing by 4 months after the operation. Nine patients had an average elevation of the hearing threshold for pure tones in the speech frequency range (500 to 2000 Hz) of 11 dB or more at 4 to 5 days after the operation; 8 of these had fluid in their middle ears that most likely contributed to the hearing loss. Threshold elevations occurred at 4000 Hz and 8000 Hz in 19 and 29 ears, respectively.

Audiometry, Evoked Response↗

Day surgery: the value of monitored anesthesia care and intraoperative monitoring.

Recently an increasing percentage of patients is receiving care and surgical procedures in Day Surgery (DS), undergoing local or loco-regional anesthesia techniques, to which many patients appear to be rather reluctant and show fear and anxiety. The anesthesiologist can resolve this problem administering i.v. hypnotic and analgesic drugs and adjusting their level to patient's needs and type of surgery. They increase the patient's compliance to DS care and contribute to its diffusion. Nowadays, commonly used drugs permit quick changes of anesthesia depth with a fast and safe recovery but these require an appropriate monitoring in order to prevent and rapidly detect the onset of complications. In this study we analyze the peculiarity of Monitored Anesthesia Care and the appropriate intraoperative monitoring especially regarding the use of pulse oximetry.

Ambulatory Surgical Procedures↗

Cortical evoked potential monitoring. A system for intraoperative monitoring of spinal cord function.

This report describes the intraoperative use of a somatosensory cortical evoked potential system to monitor spinal cord function during 300 orthopedic surgical procedures. This system requires sophisticated equipment and the establishment of normative data but has performed well with no false negatives noted. The most frequent technical problem encountered was the effect of medications and anesthetic agents, some of which impair the evoked response significantly. In this series of 300 cases, three neurologic deficits were documented intraoperatively and confirmed postoperatively. There were four cases in which changes in evoked potentials led to change in operative procedure, with no subsequent neurologic deficit. In the remaining cases, the monitoring indicated no neurologic problems during surgery, and none were noted postoperatively.

Adolescent↗

Does preoperative paresis influence intraoperative monitoring of the motor cortex?

Intraoperative monitoring of motor function by means of motor evoked potentials (MEPs) is a new method. The current study examines the influence of preoperative paresis on the feasibility and reliability of this method. Intraoperative monitoring of MEPs was performed in 58 patients during surgery in the central region. The patients were divided into three groups according to their preoperative strength (group I, muscle strength less than or equal to grade 4 according to the British Medical Research Council grading system [n = 17]; group II, normal strength (n = 36); and group III, muscle strength less than grade 5 but not worse than grade 4 [n = 5]). The motor cortex was stimulated directly with a high-frequency monopolar anodal train. In groups II and III, MEPs were elicited in all patients on cortical stimulation, whereas in group I a response was obtained in only 88% of patients. The MEP parameters in all groups had a broad interindividual range of variation. A correlation between individual intraoperative potential changes and surgical maneuvers was observed in seven patients in group II and in four patients in group I. No MEP changes were recorded in group III. Irreversible MEP changes (groups I and II) resulted in postoperative clinical deterioration. No postoperative deterioration of motor function was observed in patients with reversible MEP changes. Preoperative paresis reduces the feasibility of the method; however, it has no influence on the intraoperative pattern and reaction of the MEPs.

Adolescent↗

[New monitoring method for the pudental nerve during surgery: cases of intraoperative monitoring for lumbo-sacral lipomeningocele].

We carried out intraoperative monitoring of the pudental nerve while separating vertebral spinal tumors from the spinal cord in five patients, including four infants. Although monitoring using a manometer or needle electrodes has been reported, monitoring done with disk electrodes to ascertain the compound muscle action potential (CMAP) of the external sphincter muscle has not been yet attempted. Prior to the surgical procedure, we locate a point suitable for CAMP recording of the muscle. In our recent study, we determined that maximum action potentials were recorded in the part with the greatest depth from the individual anal verge. Therefore, the depth of the anal canal was preoperatively measured for the manometry method, and sphincter electrodes currently on the market were refigured to suit the infant's anal canal. After the two procedures described above, we were able to preserve the pudental nerves intraoperatively. The postoperative neurological findings of all five patients were unchanged. We introduce here this new method of intraoperative monitoring for preserving the pudental nerve.

Action Potentials↗

[Intraoperative monitoring of visual evoked potentials].

Our success rate of intraoperative monitoring of visual evoked potential (VEP) had been approximately 30% in the past. In order to improve recording rate of intraoperative VEP, we developed a new stimulating device using high power light emitting diodes. Electroretinogram was simultaneously recorded to understand whether flash stimulation reached the retina. In addition, total venous anesthesia with propofol was used to avoid the adverse effect of inhalation anesthesia. We report the results after introduction of these improvements. Intraoperative monitoring of VEP was attempted in 35 cases. We evaluated success rate of VEP recording, correlation between VEP findings and postoperative visual function, and reasons why recording was not successful. Stable and reproducible waveforms were obtained in 59 sides (84%). Two cases, whose VEP deteriorated intraoperatively, developed postoperative visual disturbance: In 11 sides (16%), stable waveforms were not obtained. There were two main causes. In 8 sides out of 11, the cause was attributed to pre-existing severe visual disturbance. In these 8 sides, VEP in the awake state was not recordable or was recordable, but with very low amplitudes under 1 microV. In the other 3 sides, the cause was attributed to movement of a stimulating device by reflecting the fronto-temporal scalp flap. In conclusion, the successful recording rate was increased to 84% from approximately 30%, after introduction of various trials. We need further improvement in recording intraoperative VEP to establish a reliable intraoperative monitoring method for VEP.

Aged↗

[Intraoperative monitoring using transesophageal 2-dimensional echocardiography].

Currently used monitoring techniques, such as measurements of blood pressure and heart rate, provide incomplete information about cardiac function during surgery. Invasive monitoring like intraoperative pulmonary artery pressure measurement with flow-directed balloon catheters may be more sensitive to detect cardiac instability, but they are associated with potentially fatal complications such as dysrhythmias and pulmonary artery rupture. In search of a more informative and yet safe intraoperative hemodynamic monitoring system, we have investigated the use of 2-D transoesophageal echocardiography (TEE). So far more than 400 patients were studied by TEE for up to 12 hours during elective surgery without any complications. High quality recordings of the left ventricle (LV) could be obtained in 87% of all patients. On the basis of the results presented below, we believe that TEE holds three fundamental advantages over the existing monitoring systems: it is inherently safer than intravascular measures, it allows direct assessment of LV filing, and it provides direct information on global and regional LV wall motion.

Abdomen↗

Intraoperative monitoring of motor cranial nerves in skull base surgery.

Intraoperative monitoring of cranial nerves is performed to minimize postoperative cranial nerve dysfunction. We performed electrophysiologic monitoring of motor cranial nerves with a NIM 2 unit from Xomed Treace and a patient multiplexer developed in our clinic. This multiplexer allows simultaneous monitoring of four cranial nerves and is additionally equipped with a bipolar stimulation mode. This intraoperative monitoring was used during 102 skull base operations. Of these, 44 operations were acoustic neuroma removals by translabyrinthine approach and 36 by a middle fossa approach. Various operations, including removal of tumors of the jugular foramen and the infratemporal fossa, were performed in the remaining 22 patients. The facial nerve, being the most frequently monitored nerve, was evaluated both preoperatively and intraoperatively. Electrophysiologic data were evaluated with respect to their predictive value for postoperative facial nerve function. The relative percent decrease in amplitude of the electromyogram after resection compared to that observed before resection seems to be of some predictive value for the postoperative facial nerve function. A 50 to 60% decrease or more is associated with an increase in the House classification. Intraoperative monitoring is a useful tool in skull base surgery, allowing for safer and faster identification of motor nerves in pathologic-anatomic conditions. It allows the surgeon a degree of comfort by providing immediate information regarding the status of the nerve. It may also improve postoperative nerve function and shorten operating time. Additionally, neuromonitoring provides some information about expected postoperative facial nerve function.

Journal Article↗

Transesophageal echocardiography. A technique for intraoperative monitoring.

Cardiac ischemia and myocardial infarction continue to be major causes of perioperative morbidity and mortality, despite aggressive intraoperative monitoring. Intraoperative TEE is evolving as a helpful noninvasive monitor in patients with coronary artery disease and valvular heart disease. Early detection of ischemia and evaluation of valve function with continuous imaging has allowed the use of TEE as a dynamic tool to optimize therapeutic management of cardiac dysfunction that was not always readily available by conventional invasive techniques. As new equipment and techniques are developed, this monitoring method will undoubtedly find even more frequent intraoperative use.

Coronary Artery Bypass↗

Isoflurane compared with nitrous oxide anaesthesia for intraoperative monitoring of somatosensory-evoked potentials.

Intraoperative monitoring of somatosensory-evoked potentials is a routine procedure. To determine the depressant effect of nitrous oxide relative to isoflurane, the authors recorded the scalp, cervical and brachial plexus-evoked responses to stimulation of the median nerve under different anaesthetic conditions. Eight subjects, age 35 +/- 6 (SD) yr, weight 68 +/- 12 kg, were studied. Following recording of awake control responses, anaesthesia was induced with thiopentone 5 mg.kg-1 and fentanyl 3 micrograms.kg-1 and was followed by succinylcholine 1 mg.kg-1. During normocapnia and normothermia, and with a maintenance infusion of fentanyl 3 micrograms.kg-1.hr-1, evoked potential recording was repeated under three different anaesthetic conditions; 0.6 MAC nitrous oxide, 0.6 MAC nitrous oxide +/- 0.6 MAC isoflurane, and 0.6 MAC isoflurane. Among the anesthetic conditions, the combination of nitrous oxide-isoflurane had the most depressant effect on the cortical amplitude (67 +/- 4% reduction, P < 0.05). Nitrous oxide decreased the cortical amplitude more than an equipotent dose of isoflurane (60 +/- 4% vs 48 +/- 7%, P < 0.05). The latency was unchanged by nitrous oxide, but increased slightly by isoflurane and isoflurane-nitrous oxide anaesthesia (1.0 and 0.9 msec respectively, P < 0.05). We conclude that somatosensory-evoked potential monitoring is feasible both during nitrous oxide anaesthesia and isoflurane anaesthesia, but the cortical amplitude is better preserved during 0.6 MAC of isoflurane alone relative to 0.6 MAC of nitrous oxide alone. The depressant effect is maximal during nitrous oxide-isoflurane anaesthesia but less than the predicted additive effect.

Adult↗

Method of anaesthesia in thyroid surgery with intraoperative monitoring of the recurrent laryngeal nerves.

INTRODUCTION: The incidence of injury of the recurrent laryngeal nerve (RLN) in various types of surgery is reported to be as high as 12%. By monitoring the recurrent laryngeal nerve intraoperatively we can identify it and preserve it even in atypical positions or in operations for processes involving the nerve. These types of surgery give rise to some specific problems facing the anaesthesiologist and the method of anaesthesia used. AIM: The aim of the study was to assess the efficacy and relevance of an anesthetic method in thyroid surgery with intraoperative monitoring of the RLN. Tasks: 1. To determine the level of myorelaxation in anaesthetic patients by intraoperative neurostimulation of the ulnar nerve. 2. By careful dosing of the non-depolarizing myorelaxants to create a "window" in the myorelaxation immediately before identification of the RLN that is detected by a neurostimulator. MATERIAL AND METHODS: Forty eight patients subjected to different types of thyroid surgery were given inhalational anaesthesia with supplementation of non-depolarizing myorelaxants. The level of relaxation was constantly monitored by neurostimulation of the left ulnar nerve. This peripheral stimulation allows creating a "window" in the myorelaxation just before the identification of the recurrent laryngeal nerve. RESULTS: There were no perioperative complications in all patients as to both surgery and anesthesia; postoperative comfort was achieved. The recurrent laryngeal nerve was readily identified and its function was preserved in the postoperative period. CONCLUSIONS: The authors consider as a method of choice the general inhalational anaesthesia supplemented with non-depolarizing myorelaxants and permanent intraoperative monitoring of the level of relaxation in surgery with intraoperative monitoring of the cranial nerve and recurrent laryngeal nerve.

Adolescent↗

[Intraoperative monitoring of motor cranial nerves in operations of the neck and cranial base].

Intraoperative monitoring of cranial nerves is performed to minimize postoperative cranial nerve dysfunction. We performed electrophysiological monitoring of motor cranial nerves with a NIM 2 unit from Xomed Treace and a patient multiplexer developed in our clinic. This multiplexer allows simultaneous monitoring of 4 cranial nerves and is additionally equipped with a bipolar stimulation mode. This intraoperative monitoring was employed during 102 skull base operations. Of these 102 operations, 44 were acoustic neuroma removals by translabyrinthine approach and 36 by a middle fossa approach. Various operations including removal of tumours of the jugular foramen and the infratemporal fossa were performed in the remaining 22 patients. The facial nerve, being the most frequently monitored nerve, was evaluated both pre- and intraoperatively. Electrophysiologic data were evaluated with respect to their predictive value for postoperative facial nerve function. The relative per cent decrease in amplitude of the EMG after resection compared to that observed before resection seems to be of some predictive value for postoperative facial nerve function. A 50-60% decrease or more is associated with an increase in the House classification. Intraoperative monitoring is a useful tool in skull base surgery allowing for safer and faster identification of motor nerves in pathologic anatomic conditions. It allows the surgeon a degree of comfort by providing immediate information regarding the status of the nerve. It may also improve post-operative nerve function and shorten operating time. Additionally, neuromonitoring provides some information about expected postoperative facial nerve function.

Cranial Nerves↗