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Results for “Monitoring, Intraoperative”

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PubMed1988

[Intraoperative monitoring with visual and auditory evoked potentials].

Intraoperative monitoring techniques concerning evoked potentials have been used during operations on the spinal cord as well as in carotid endarterectomy and in aneurysm surgery. The monitoring of early acoustic evoked potentials during surgery of the posterior fossa and the registration of the visually evoked potentials in patients suffering from pituitary adenoma or other space occupying lesions of the sella region seem to provide information about function of nerves and brain stem structures. This paper deals with positive and negative aspects of intraoperative monitoring of visual and acoustic evoked potentials.

Brain Neoplasms↗

PubMed2005

[Function of the facial nerve after operative treatment of acoustic neurinomas. Influence of intraoperative monitoring].

The aim of this study was to evaluate the influence of intraoperative monitoring on the function of the facial nerve after surgical treatment of acoustic neurinomas, classified according to the grading system of Stennert. One hundred thirty patients were divided into two groups. The first group underwent surgery without intraoperative facial monitoring; the second group included intraoperative facial monitoring. Concerning degree of paresis, preoperatively there was no statistically significant difference between the two groups (group 1: 0.77+/-1.5; group 2: 0.4+/-1.2). Despite structural preservation of the facial nerve, postoperative deterioration of its function was observed which consecutively improved postoperatively. Postoperatively, the mean degree of paresis increased to 4.4+/-3.0 in group 1 and 2.4+/-2.3 in group 2. For better understanding of the role of intraoperative monitoring, we investigated the outcome of patients with acoustic neurinomas who underwent surgery over the following 6 months postoperatively. At that time, function improved by 4.1+/-3.2 (group 1) and 2.0+/-2.3 (group 2). We could show that intraoperative monitoring of the facial nerve was a significant factor for better postoperative function in patients undergoing microsurgical excision of neurinomas (P=0.001) .

Facial Nerve↗

PubMed1995

Direct spinal stimulation for intraoperative monitoring during scoliosis surgery.

Intraoperative electrophysiological monitoring of the spinal cord has traditionally been done by recording somatosensory evoked potentials (SEP). There is a risk that SEPs can be unaltered when significant injury to the anterior spinal cord has occurred. The purpose of this report is to describe a simple technique for intraoperative spinal cord stimulation which monitors descending pathways in the anterior spinal cord. Stimulation occurs through needle electrodes inserted into spinous processes in the rostral surgical wound, and recordings are made from electrodes in the popliteal spaces. We report our experience in monitoring spinal instrumentation in 45 patients with idiopathic scoliosis and 20 with some form of neurological disease causing scoliosis. The neurogenic motor evoked potentials (NMEP) are stable and easily recorded from the popliteal spaces in the majority of patients. We describe the case of 1 patient with Friedreich's ataxia in whom no SEPs could be recorded, but NMEPs were used successfully for monitoring. We have fond that combining traditional SEP monitoring with NMEP recording provides a safe and effective method to monitor the spinal cord during surgical procedures where it is at risk.

Adolescent↗

PubMed1995

[Is intraoperative monitoring of transesophageal echocardiography necessary for mitral valve repair?].

To clarify the clinical significance of the intraoperative monitoring for mitral valve repair by transesophageal echocardiography (TEE), we evaluated the correlation of color Doppler flow area of residual mitral regurgitation (residual MR area) between intraoperative and postoperative TEE. Subjects were 12 patients (average age was 54.7 years) underwent recently intraoperative TEE. These 12 patients were divided into two groups: Group A (MR area < 2.0 cm2; n = 8) and Group B (MR area > 2.0 cm2; n = 4). None of the 12 patients required second pump run. In all cases, residual MR area, as determined using intraoperative TEE, was less than 3.2 cm2. One month after surgery, the MR area did not showed an increase in Group A, while in Group B it decreased slightly in 2 cases, remained unchanged in 1 case and increased slightly in 1. Our findings do not support the usefulness of intraoperative monitoring with TEE. It seems difficult to predict the outcome of residual MR on the basis of the MR area alone. At present, we thought that, possibly, intraoperative monitoring with TEE is indispensable for mitral valve repair. A longer follow-up will be necessary to draw firm conclusions.

Echocardiography, Transesophageal↗

PubMed2004

Intraoperative monitoring during vascular surgery.

The principal objectives of intraoperative monitoring are to improve perioperative outcome, facilitate surgery and reduce adverse events, using continuously collected data of cardiopulmonary,neurologic and metabolic function to guide pharmacologic and physiologic therapy. Although sophisticated and reliable apparatus may be used to collect these data they are useless, or even harmful, without proper interpretation. This article provides a comprehensive overview of recent publications on the history,philosophy, and semantics of monitoring.

Animals↗

PubMed2004

Intraoperative monitoring of cochlear function using distortion product otoacoustic emissions (DPOAEs) in patients with cerebellopontine angle tumors.

HYPOTHESIS: Intraoperative monitoring by distortion-product otoacoustic emissions reflects the cochlear function changes in the real-time domain during removal of cerebellopontine angle tumors. BACKGROUND: Cerebellopontine angle tumor surgery is associated with a significant risk of damaging internal auditory canal contents. Although monitoring facial nerve function intraoperatively has already been effectively developed, such efficacious monitoring of auditory function remains to be established. The aim of this study was to investigate the utility of distortion-product otoacoustic emissions for intraoperative monitoring of the cochlear function in humans during removal of cerebellopontine angle tumors. METHODS: Continuous intraoperative monitoring of distortion-product otoacoustic emissions was performed in 20 of 62 patients undergoing surgical removal of cerebellopontine angle tumors. All of these 20 patients, who underwent the retrosigmoid approach, had distortion-product otoacoustic emissions present preoperatively. Depending on the amplitude and frequency band at which distortion-product otoacoustic emissions were present, monitoring was carried out at 2.0 to 6.0 kHz with primary stimulus tone amplitudes of 60 to 70 dB sound pressure level. RESULTS: In patients operated on for cerebellopontine angle tumors, various patterns of distortion-product otoacoustic emission amplitude reductions and recoveries were observed. Distortion-product otoacoustic emissions recorded from the basal part of the cochlea (i.e., high frequencies) changed earlier and more profoundly than those from the middle and apical sections (i.e., lower frequencies). In some cases, cochlear function was affected irreversibly as reflected by loss of distortion-product otoacoustic emissions. Microcoagulation of small vessels, tumor debulking, and compression or stretch of the internal auditory canal contents were found to be procedures affecting distortion-product otoacoustic emissions. The status of distortion-product otoacoustic emissions at the conclusion of tumor dissection correlated with postoperative hearing levels. CONCLUSION: Distortion-product otoacoustic emissions were used to monitor in the real-time domain auditory function during cerebellopontine angle tumor removal operations. The status of distortion-product otoacoustic emissions at the conclusion of the operations was related to postoperative hearing.

Adult↗

PubMed2000

Experimental study of medullary trigeminal evoked potentials: development of a new method of intraoperative monitoring of the medulla oblongata.

OBJECT: The goal of this study was to develop a new method of intraoperative monitoring of functions located in the lateral portion of the medulla oblongata. Based on the fact that the spinal trigeminal nucleus and tract are located in the lateral portion of the medulla oblongata, the authors intended to investigate the efficacy of trigeminal evoked potentials (TEPs) in intraoperative monitoring for assessing functions of the medulla oblongata. METHODS: Trigeminal evoked potentials induced by electrical stimulation of the infraorbital nerve were recorded from the dorsolateral portion of the medulla oblongata (M-TEP) and the cerebral sensory cortex (C-TEP) in dogs. When the lateral one-sixth portion of the medulla was cut, the amplitude of the M-TEP decreased markedly, but the amplitude of the C-TEP and the somatosensory evoked potential (SSEP) did not decrease. When the lateral one-third portion of the medulla was cut, the amplitude of the SSEP decreased, but that of the C-TEP showed no change. When the medulla was retracted, the amplitude of the M-TEP was more sensitive than that of SSEP. Pathological examinations revealed that retraction force less than 10 g and a reduction in the amplitude of the M-TEP less than 50% were safe. CONCLUSIONS: These results suggest that M-TEPs obtained from the dorsolateral portion of the medulla oblongata by electrical stimulation of the trigeminal nerve are clinically applicable as a new means of intraoperative monitoring of the functions of the medulla oblongata.

Animals↗

PubMedDate not supplied

[Evaluation of the capacities of neurophysiological intraoperative monitoring in reconstructive surgery on the vertebral column].

AIM: To evaluate the capacities of neurosurgical intraoperative monitoring of somatosensory evoked potentials (SSEP) in reconstructive operations on the vertebral column. MATERIALS AND METHODS: The Center of Spinal Surgery examined 30 patients treated in February to July 2001. According to the diagnosis, the distribution was as follows: degenerative diseases of the vertebral column (80%), its tumors (10%), injury (7%), and inflammatory diseases (3%). Of them, 13 (43.3%) patients underwent anterolateral decompression of the dural sac of roots, 17 (56.7%) had traditional decompression of the dural sac and roots from the posterior access. The study was carried out on an 8-channel electrophysiological Viking-IV system (Nicolet, USA). Intraoperative SSEP monitoring was made by the routine procedure. The amplitude and latent time of subcortical peaks (P31) were determined at surgery. Intraoperative SSEPs were classified as defined with the American Electroencephalographic Society. The changes in the basic parameters of SSEP were also divided into transient (under 30 minutes) and permanent (above 30 minutes). RESULTS: True positive responses (significant changes in intraoperative SSEPs and the presence of postoperative neurological disorders) were 3.3% (1 patient); false positive ones (significant changes in intraoperative SSEPs without postoperative neurological disorders) were 23.3% (7 patients). False negative responses (normal intraoperative SSEPs and the presence of postoperative neurological disorders) were absent. The findings indicate that new postoperative neurological disorders should not be expected in patients with the clinical picture of mild neurological disorders if they have transient changes in the basic parameters of SSEPs that last at least 30 minutes. At the same time a risk group includes patients with severe neurological disorders since in these patients, compensatory capacities are primarily decreased and intraoperative exposures may result in early spinal circulatory decompensation. More frequent (every 10 minutes) recording of intraoperative SSEPs is also recommended for this group of patients is complicated surgical manipulations. CONCLUSIONS: 1. Neurophysiological intraoperative monitoring yields additional information for surgeons during an operation. 2. During intraoperative monitoring of SSEPs, it is necessary to assess any changes in the latter as true and to immediately find possible causes of these changes. 3. In patients with revealed spondylogenic spinal circulatory disorders and severe neurological disorders, even short-term changes in SSEPs should be assessed with particular carefulness before surgery.

Adolescent↗

PubMed1994

Intraoperative monitoring of auditory function: experimental observations and new applications.

The three different methods of intraoperative monitoring, namely, auditory brainstem response evaluation (ABR), electrocochleography (ECoG), and direct eighth nerve compound action potentials monitoring are reviewed. Both ECoG and direct eighth nerve monitoring surpass the ABR in their ability to provide fast, almost instantaneous, large, reproducible potentials in response to click stimuli. Changes in the amplitude and the latency of these potentials alert the surgeon of an impending eighth nerve injury. Human clinical observations revealed instances of persistence of the ECoG despite a total eighth nerve section in the cerebellopontine angle. Animal and human experiments were conducted to evaluate the effectiveness of ECoG and direct eighth nerve monitoring in hearing preservation. Twelve cats underwent progressive sectioning of the eighth nerve with simultaneous monitoring of changes in their ECoG and direct eighth nerve potentials. ECoG thresholds were obtained intraoperatively in eight patients undergoing surgery for conductive hearing loss. The results of these experiments suggest that recording directly from the eighth nerve is a more accurate technique during cerebellopontine angle and eighth nerve surgery. ECoG, however, appears to have a promising role in the intraoperative monitoring of middle ear reconstruction procedures under general anesthesia.

Action Potentials↗

PubMedDate not supplied

[Intraoperative monitoring of a neuromuscular conduction blockade].

Preliminary results of intraoperative monitoring of the degree of neuromuscular blockade using a portable device based on the technique of evoked electromyography are presented. The device has an analogue outlet for the connection with a computer. The technique used is simple and reliable and makes it possible to work out a computerized system for automatic graded supply of current myorelaxants on a feedback principle. Such a system does not only ensure an adequate level of myorelaxation with a minimum expenditure of expensive drugs, but also gives a new approach to the study of neuromuscular conduction during anesthesiological supply in various surgical interventions.

Adolescent↗

PubMed2002

Regulatory and medical-legal aspects of intraoperative monitoring.

Public policies are in place for health care to insure high quality, organized delivery of care to patients. Public policy issues for intraoperative monitoring include billing, coding, reimbursement, staffing, device approval, and liability. Staffing issues include privileging, credentialing, certifying, training, and professionalism. Those staffing processes provide ways that the profession passes judgment on individual's skills, knowledge, abilities, and training relevant to monitoring. These issues are reviewed here, along with a discussion of the respective roles of physicians and non-physicians in monitoring. Various billing codes for intraoperative monitoring are reviewed along with the circumstances in which they are to be used. Policy on the use of non-approved devices is also presented.

Credentialing↗

PubMed2003

[Intraoperative monitoring of the facial nerve: anesthesia and neurophysiology considerations].

Intraoperative monitoring of the motor component of the 7th cranial pair or any other nerve should be routine during any surgical procedure involving risk of neural damage, whether or not the skull is opened. This paper discusses the main indications for monitoring facial and acoustic nerves during ear and neurosurgery involving the pontocerebellar angle (for acoustic neuroma or in surgery on the 8th cranial pair). Intraoperative electromyographic monitoring of the facial nerve should be used routinely in acoustic neuroma surgery to reduce the degree of postoperative neurological impairment and avoid possible malpractice suits. Although such monitoring requires that the muscle remain unblocked, intraoperative neuromuscular relaxants can be used if doses are administered along with appropriate monitoring of the level of peripheral neuromuscular block.

Anesthesia↗

PubMedDate not supplied

[Predictive value of intraoperative monitoring of brainstem acoustic evoked potentials during removal of parabrainstem tumors].

The data of intraoperative monitoring of brainstem acoustic evoked potentialities (BAEP) during parabrainstem tumors are analyzed. Of the 24 cases, 16 patients were found to have neurinoma of the acoustic nerve, 4 had petroclival meningioma, 2, tentorial meningioma, 1, cholesteatoma of the cerebellopontine angle, and 1, brainstem angioma. The authors proposed to identify the favorable and unfavorable patterns of BAEP as predictors of an early postoperative period, by comparing the patterns of BAEP, the data on the monitoring vital functions and outcomes of disease. The conformity of actual and predictable results was analyzed. By taking into account the high coincidence of actual and predictable outcomes (79.16%), it can be suggested that the data of intraoperative monitoring of BAEP are not only of value for obtaining information at the moment of surgery, but also informative as a predictor of an early postoperative period and outcomes of disease.

Adult↗

PubMed2005

Intraoperative monitoring of motor symptoms using surface electromyography during stereotactic surgery for movement disorders.

The authors present practical evidence for the usefulness of intraoperative monitoring with surface electromyograms (sEMGs) from the affected muscles to assist electrode implantation and lesioning in patients with movement disorders. In 22 consecutive patients with various movement disorders, sEMGs were monitored in selected muscles during stereotactic surgery that involved either lesioning or electrode implantation. The electromyograms related to major motor symptoms such as tremor, rigidity, myoclonus, dystonia, and chorea were monitored and characterized on-line by both amplitude and frequency. Major motor symptoms were revealed by sEMGs recorded from the affected muscles. Tremor manifested as highly rhythmic bursts with a narrow frequency band; dyskinesias and chorea appeared as irregularly repeated bursts within a broad frequency range of 1 to 5 Hz; and rigidity and dystonia appeared as sustained high-frequency activity and co-contraction between antagonist muscles. The results suggest that intraoperative monitoring of sEMGs could help to functionally refine and confirm target localization. Surface EMGs could be used (1) as reference signals of the motor symptoms so that other signals, such as the oscillatory local field potentials simultaneously recorded via the implanted electrodes, could be correlated with the sEMGs and used to fine-tune or confirm the target localization; (2) to quantify the effects of acute electrical stimulation on the motor symptoms; and (3) to sensitively detect unwanted capsular responses induced by direct stimulation of the internal capsule. The authors conclude that intraoperative monitoring of sEMGs of the affected muscles of patients with movement disorders during stereotactic surgery provides sensitive and quantitative information that can contribute to improved electrode or lesion placement.

Electric Stimulation↗

PubMed1990

Intraoperative monitoring of facial nerve function in cerebellopontine angle surgery.

Facial nerve paralysis associated with cerebellopontine angle surgery has been reported to range up to 26% in a recent series. Various methods of intraoperatively monitoring the facial nerve have been developed to reduce the incidence of facial paralysis. We report our experience with an intraoperative monitoring technique using intramuscular EMG electrodes to detect subclinical electrical responses that were amplified and made audible to the operating surgeon after gating stimulus artifacts. A 3.6% incidence of facial paralysis in 111 consecutive cases with this intraoperative monitoring method compared with 14.5% in 207 previously unmonitored cases indicates significant reduction of this complication in cerebellopontine angle surgery (p less than 0.001). Along with this reduction in facial paralysis, an increase in the percentage of partial facial paresis was observed in the monitored group (p less than 0.05). The percentage of those with intact facial function was similar in the monitored (82.0%) and unmonitored groups (78.3%).

Cerebellar Diseases↗

PubMed1984

[Methodologic aspects of the intraoperative monitoring of evoked potentials].

The aim of intraoperative monitoring methods is to obtain early information about central nervous function during critical phases of the operation. To this end it can be useful to accept modifications of the method or the technical parameters such as changes of the electrode positions, of the system's bandpass, the analysis time or the number of sweeps used for averaging. Additionally emphasis is laid upon the fact that there is no knowledge concerning the critical changes of potential which might indicate functional disturbances or impending postoperative neurological deficits. At the present time intraoperative EP-Monitoring is not an established method for clinical use. Evidence is lacking that supervision of the operation by these means results in a reduced operation risk.

Electrodes↗

PubMedDate not supplied

[Intraoperative monitoring of nerve roots in spinal surgery].

INTRODUCTION: The use of intraoperative monitoring to determine the functional integrity of the nervous system has grown steadily over the last 15 years. The development of new instrumentation systems in spinal surgery and a greater incidence of complications have led to the need to introduce new methods of monitoring. AIMS AND DEVELOPMENT: The purpose of this study is to analyse the neurophysiological techniques that are currently available and applied in order to prevent injury to nerve roots and the fibres of the cauda equina, to assess their indications and to determine their limitations, as well as the effects caused by anaesthesia.

Electromyography↗

PubMed1991

Noninvasive intraoperative monitoring of motor evoked potentials under propofol anesthesia: effects of spinal surgery on the amplitude and latency of motor evoked potentials.

We present the results of intraoperative monitoring of motor evoked potentials from 34 patients undergoing spinal surgery under total anesthesia with intravenously administered propofol. Intraoperative recording was performed with transcranial electrical stimulation. Two groups of patients were studied: 1) a control population of 26 patients undergoing lumbar discectomy for prolapsed intervertebral disc, all of whom had normal preoperative motor conduction; and 2) a population of 8 patients undergoing neurosurgical procedures for spinal tumor (5 patients) and spinal arteriovenous malformation (3 patients), all of whom had abnormal preoperative neurological signs and abnormal preoperative motor conduction. In the first group, electromyographic responses were recorded intraoperatively either from the 2nd dorsal interosseous muscle of the hand (5 patients) or from the 1st dorsal interosseous muscle of the foot (21 patients). In the second group, responses were recorded intraoperatively either from the 1st dorsal interosseous muscle of the foot (7 patients) or from the anterior tibial muscle (1 patient). Intraoperative monitoring of motor function was successful in 88.5% of the patients in the control group. Propofol anesthesia caused a reduction in response amplitude to 7% of baseline values obtained from conscious relaxed subjects. Intraoperative monitoring was successful in 87% of the patients in the pathological group. We observed significant changes in both amplitude (greater than 50%) and/or onset latency (greater than 3 ms) from the intraoperative baseline that indicated either improvement (3 patients) or deterioration (2 patients) in motor conduction within minutes of surgical maneuvers anticipated to alter spinal cord function. Only permanent complete loss of intraoperative motor conduction (1 patient) correlated with a significant change in the postoperative neurological state.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗