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At least 595 records · Page 33Linked to original sources
PubMed1985

Intraoperative sonographic monitoring of reduction of thoracolumbar burst fractures.

Intraoperative real-time sonography was used to monitor surgical reduction of acute thoracolumbar burst fractures in eight patients. Real-time sonography was performed after laminectomy through a saline-filled operative field using either a 5.0 or a 7.5 MHz transducer. Sonography was performed during Harrington rod distraction and during fracture reduction to confirm adequacy of decompression of the spinal canal. This technique is useful to monitor surgery and in defining adequate fracture reduction.

Adult↗
PubMed2003

Brain surgery in motor areas: the invaluable assistance of intraoperative neurophysiological monitoring.

AIM: Surgery for tumors in the central and precentral region, as much as for insular tumors, places at risk the functional integrity of the motor cortex and the subcortical motor pathways. These procedures may therefore benefit from the assistance of intraoperative neurophysiological monitoring (INM). INM consists of "mapping" and true "monitoring" (the continuous "on-line" assessment of the functional integrity of neural pathways) techniques. In spite of the large interest in mapping techniques, monitoring techniques have received less attention. We describe our experience with intraoperative neurophysiological mapping and monitoring of motor tracts during surgery for brain gliomas in or near motor areas, in order to support the feasibility and reliability of monitoring as an essential adjunct to mapping during surgery in these areas. METHODS: Between September 2000 and January 2002, 51 patients were surgically treated for brain gliomas located in the precentral gyrus (45.1%), the postcentral gyrus (23.5%), anterior to the precentral gyrus (15.6%), or in the insula (15.6%). INM of the motor system consisted of monitoring muscle motor evoked potentials (mMEPs) recorded via needle electrodes inserted into the controlateral upper and lower extremity muscles and elicited by transcranial multipulse electrical stimulation (TES). Once the dura was open and the central sulcus was identified using the phase reversal technique, mMEPs were elicited by direct stimulation of the motor cortex (DCS). Motor mapping was performed with a monopolar electrode using the same stimulation parameters as used for monitoring except for much lower intensity (up to 20 mA). RESULTS: Ninety-eight percent of the patients exhibited recordable baseline mMEPs. The success rate of the phase reversal technique was 95.8%. Eight patients presented disappearance of mMEPs during tumor removal. Using corrective measures, all intraoperative changes in mMEPs were reversed in time to prevent an irreversible complete injury to the motor system and no patient lost mMEPs at the end of the operation. At discharge, 66% of the patients remained at their preoperative status, 4% improved, and 24% had a mild worsening as compared to the preoperative status assessed using the Medical Research Council scale; 6% of the patients presented a moderate to severe supplementary motor area syndrome. CONCLUSION: Monitoring techniques significantly implement the reliability and effectiveness of INM since these provide: 1) continuous "on-line" assessment of the functional integrity of motor pathways with higher chance to early detect a progressive mechanical or vascular injury to the neural tissue, as compared to mapping techniques; 2) lower risk to induce intraoperative seizures and strong muscular twitches as compared to the single pulse mapping technique; 3) possibility to monitor motor pathways using TES also when there is no direct access to the motor cortex.

Adult↗
PubMed1993

A review of brain retraction and recommendations for minimizing intraoperative brain injury.

Brain retraction is required for adequate exposure during many intracranial procedures. The incidence of contusion or infarction from overzealous brain retraction is probably 10% in cranial base procedures and 5% in intracranial aneurysm procedures. The literature on brain retraction injury is reviewed, with particular attention to the use of intermittent retraction. Intraoperative monitoring techniques--brain electrical activity, cerebral blood flow, and brain retraction pressure--are evaluated. Various intraoperative interventions--anesthetic agents, positioning, cerebrospinal fluid drainage, operative approaches involving bone resection or osteotomy, hyperventilation, induced hypotension, induced hypertension, mannitol, and nimodipine--are assessed with regard to their effects on brain retraction. Because brain retraction injury, like other forms of focal cerebral ischemia, is multifactorial in its origins, a multifaceted approach probably will be most advantageous in minimizing retraction injury. Recommendations for operative management of cases involving significant brain retraction are made. These recommendations optimize the following goals: anesthesia and metabolic depression, improvement in cerebral blood flow and calcium channel blockade, intraoperative monitoring, and operative exposure and retraction efficacy. Through a combination of judicious retraction, appropriate anesthetic and pharmacological management, and aggressive intraoperative monitoring, brain retraction should become a much less common source of morbidity in the future.

Adrenal Cortex Hormones↗
PubMed2004

Does intraoperative electromyographic monitoring in lumbar microdiscectomy correlate with postoperative pain?

OBJECTIVES: Our objective was to correlate the findings of intraoperative electromyographic (EMG) monitoring with immediate postoperative pain in patients undergoing lumbar microdiscectomy. METHODS: A total of 112 patients undergoing de novo lumbar microdiscectomy were prospectively randomized into a control group (n = 45) and a study group (n = 67) in which intraoperative EMG monitoring was used. Postoperative pain and postoperative narcotic consumption were recorded for each patient. RESULTS: The presence or absence of EMG monitoring did not influence the level of reported pain in any anatomic area. In the monitored group, the degree of recorded nerve root irritation did not correlate with reported pain or postoperative narcotic consumption. The level of back pain was found to be significantly higher than the level of hip and calf pain (P < 0.0001). CONCLUSIONS: In our study no correlation was found between intraoperative EMG findings and immediate postoperative pain.

Adolescent↗
PubMed2001

Intraoperative metabolic monitoring of the heart: I. Clinical assessment of coronary sinus metabolites.

Numerous clinical studies have corroborated the ability of intraoperative sampling of coronary sinus blood to measure changes in myocardial metabolism induced by ischemia and reperfusion. Among other changes, cardiac arrest induces a period of obligate myocardial lactate production that persists for an indeterminate amount of time after reperfusion. Coronary sinus lactate assays have been established as a standard method to compare various myocardial protection strategies. Current methodology requires detailed sample processing, precluding real-time feedback in the operating room. Newer devices hold promise in allowing the online assessment of myocardial metabolism; however, these methods await precise validation.

Energy Metabolism↗
PubMed1999

Intraoperative electromyogram monitoring of the recurrent laryngeal nerve: experience with an intralaryngeal surface electrode. A method to reduce the risk of recurrent laryngeal nerve injury during thyroid surgery.

INTRODUCTION: A clinical method to localize the recurrent laryngeal nerve intraoperatively in order to minimize the risk of accidental injury is presented. METHODS AND RESULTS: By means of an electrode, the nerve was stimulated by a pulsed contact current. The resulting muscle potential was detected using an electrode placed in the larynx. We applied this technique during the time period between 1 January 1997 and 31 December 1998. In 96 cases of primary thyroid resection, the recurrent nerve was identified 167 times. The patients were operated on for nodular thyroid (n=85), Grave's disease (n=9) and malignant papillary goiter (n=2). Retrospectively, the rate of intraoperative nerve injury, equivalent to the rate of postoperative transient and permanent nerve palsy, was 1.04% in the 96 patients and 0.60% with respect to the 167 nerves at risk. The rate of failure of the method was 7.29%.

Electrodes, Implanted↗
PubMed1998

Surgical monitoring of motor pathways.

Intraoperative monitoring of corticospinal function is no longer an experimental technique, having been introduced into routine practice in a number of centers, each of which has now accumulated large series of some hundreds of cases. Different techniques have been developed by these centers; each has advantages and disadvantages, and it is clear that no one technique in particular is optimal for all surgical procedures. The corticospinal system can be activated by transcranial stimulation of the motor cortex or by direct stimulation of the spinal cord with electrical or magnetic stimuli delivered singly or as double or multiple pulses. The evoked activity may be recorded directly from the spinal cord using epidural electrode, or as a postsynaptic volley in motor axons ("neurogenic motor evoked potentials," MEP), or as a compound muscle action potential (CMAP) from innervated muscles. For scoliosis surgery, we use transcranial electrical stimulation, recording the evoked volley from the spinal cord using epidural electrodes at two spinal levels. By simultaneously stimulating the tibial nerves in the popliteal fossae, descending corticospinal volleys and ascending somatosensory volleys can be recorded in the same sweep. Accordingly, this technique allows monitoring of two different modalities of function at two separate levels of the nervous system, a goal that is most desirable because it helps identify the earliest evidence of dysfunction and at the same time minimizes false-positive reports to the surgeon. Our technique has the advantage of being relatively immune to the depressant effects of anesthesia, and full muscle relaxation is possible--even desirable. More peripheral recordings of neurogenic MEP or CMAP, are sensitive to the choice of anesthetic, and the latter requires incomplete curarization. However, these techniques may be appropriate when the pathology is in the low spinal cord or nerve roots.

Evoked Potentials, Motor↗
PubMed2004

Intraoperative electromyographic monitoring of the recurrent laryngeal nerve in reoperative thyroid and parathyroid surgery.

BACKGROUND: Injury to the recurrent laryngeal nerve (RLN) is a rare complication of initial thyroid and parathyroid surgery, but the prevalence is much higher in the reoperative setting. The use of continuous, intraoperative electromyographic monitoring of the RLN has been suggested to improve the safety of cervical explorations. METHODS: Outcomes of a group of reoperative thyroid and parathyroid cases that used EMG monitoring with endoscopically applied hook-wire electrodes were compared with a group of cervical reoperations without monitoring. Office laryngoscopy (indirect or fiberoptic) was used to evaluate and follow suspected RLN complications. RESULTS: Electromyography was used in 52 cervical reexploration procedures. Patients averaged 1.8 previous explorations (range, 1-7 explorations) and underwent procedures for parathyroid (31%) and/or thyroid (77%) disease (overall, 72% malignant). The non-monitored group had 59 patients with similar characteristics. Only 1 permanent nerve complication in each group was unintended (electromyography, 1.9%; non-electromyography, 1.7%). Seven false-negative and 2 false-positive electromyographic findings occurred. No complications resulted from placement of the electromyography electrodes. CONCLUSIONS: Intraoperative electromyographic monitoring of the RLN in reoperative neck surgery can be performed safely but did not decrease RLN complications in this study. Experience and routine nerve exposure remain crucial to the minimization of RLN complications.

Adolescent↗
PubMed2006

Intraoperative coagulation monitoring and small bowel transplantation: a way to explore.

BACKGROUND: The existence of coagulation disorders during intestinal transplantation is getting more important for a correct anesthetic management. Both a condition of hypocoagulation and hypercoagulation can happen during the intraoperative course. Thromboelastography (TEG), a test on whole blood coagulation, allows measurement of different phases of coagulation function. The aims of our study were to evaluate coagulation derangements during bowel transplantation using TEG. MATERIALS AND METHODS: We measured cold ischemia time in 19 patients who underwent general anesthesia for intestinal transplantation. We measured five TEG indicators (R, K, angle, MA, CL50) at defined intervals: dissection phase (T1), vascular anastomosis phase (T2), 30' (T3) and 120' (T4) after reperfusion during the intestinal reconstruction. RESULTS: We found a statistically significant difference between MA measured at T1 versus T3 and T4. There was no significant relation between MA derangements and ischemia time. CONCLUSIONS: Patients showed hypocoagulation pattern during all periods. MA indicator variation between the initial value and the value after reperfusion may relate to release of hypocoagulation factors. We observed important coagulation derangements during small bowel transplantation, particularly on platelet function after graft reperfusion. The derangements did not depend on ischemia time.

Blood Coagulation Disorders↗
PubMed1998

Advances in monitoring of seventh and eighth cranial nerve function during posterior fossa surgery.

OBJECTIVE: This study aimed to illustrate some recent advances in intraoperative monitoring of the seventh and eighth cranial nerves (i.e., direct recording of cochlear nerve action potentials [CNAPs] and facial nerve action potentials [FNAPs]). STUDY DESIGN: Reports of representative cases and average postoperative results obtained in subjects submitted to cerebellopontine angle surgical procedures are examined. Results obtained in patients with direct recording techniques are compared with those obtained with the classical monitoring techniques (auditory brain stem response [ABR], electrocochleography [ECoG], facial electromyography [EMG]). SETTING: The study was conducted at an Ear Nose and Throat Department, University of Verona, Verona, Italy. INTERVENTION: Intraoperative monitoring during cerebellopontine angle surgery was performed. RESULTS: Patients monitored with direct audiomonitoring techniques presented better postoperative auditory functions compared to patients monitored with ABR. The FNAP and EMG groups showed FN outcome that did not differ significantly. CONCLUSIONS: Intraoperative monitoring of cranial nerves furnishes a valid tool for identification of neural structures, prevention of damage, understanding of the pathophysiology of damage, and prediction of postoperative function. The fundamental prerequisite for obtaining optimal benefits from monitoring is the use of techniques of direct and continuous electrophysiologic recording with instantaneous feedback to the surgeon, such as CNAPs and FNAPs.

Adolescent↗
PubMed1997

Microvascular decompression for the treatment of hemifacial spasm. Retrospective study of a consecutive series of 75 operated patients--electrophysiologic and anatomical surgical analysis.

The authors report the results of a series of 75 patients operated on for hemifacial spasm by the same surgeon between October 1981 and January 1997. Microsurgical vascular decompression was performed through a retromastoid approach in contralateral position. The conflicting vessel was identified as the posterior inferior cerebellar artery in 41.3% of the cases, the anterior inferior artery in 38.6%, and the vertebrobasilar complex in 18.7%. Follow-up varied from 1 month to 13 years (with a mean duration of 5 years and 2 months). The outcome was excellent (total improvement) in 57 cases, good (> 75% improvement) in 11 cases, fair (< 75%) in 4 cases and poor in 3 cases. Neurological complications included deafness or hearing loss in 3 cases (2 occurred in the absence of intraoperative monitoring and the other during the first part of the series) and facial paralysis in 1 case. Brainstem auditory evoked potential (BAEP) intraoperative monitoring should be performed to avoid postoperative auditory complications; a marked auditory loss was observed in only 1.6% of the 60 patients of our series who underwent BAEP intraoperative monitoring.

Adult↗
PubMed1989

Intraoperative impedance monitoring during CT-guided stereotactic biopsies.

In this study, the relationships among computed tomography (CT) characteristics, intraoperative impedance monitoring, and histologic features were evaluated in 46 patients. Preoperatively, the CT characteristics of the proposed trajectory of the biopsy needle were determined and correlated intraoperatively with the impedance profile as obtained with a monopolar electrode. An excellent correlation between high-resolution CT density characteristics and impedance patterns was seen (r = 0.897). A correlation was also seen between CT patterns/impedance profiles and histologic features. Impedance values were also useful in predicting variation between predicted and actual needle trajectory, determining the proximity of normal structures to the probe tip and detecting loculations within cystic structures.

Biopsy↗
PubMed2001

Monitoring of intraoperative motor evoked potentials to increase the safety of surgery in and around the motor cortex.

OBJECT: The repetitive application of high-frequency anodal monopolar stimulation during surgery in or near the motor cortex allows a qualitative and quantitative evaluation of motor evoked potentials (MEPs). Using this method, motor pathways and motor function can be continuously monitored during surgery. METHODS: In this prospective study, 70 patients underwent MEP monitoring during surgery performed in the central region. All procedures were performed after general anesthesia had been induced without the aid of muscle relaxants. The motor pathways were monitored during the entire surgical procedure by repetitive high-frequency anodal monopolar stimulation (frequency 400-500 Hz; train 7-10 pulses; impulse duration 0.2-0.7 msec; and stimulation intensity 16.9 +/- 7.76 mA). The MEPs were continuously evaluated to assess their latency, potential duration, and amplitude. Recorded alterations in these parameters were subsequently correlated with surgical maneuvers and with postoperative neurological deterioration. The monitoring parameters (latency, potential duration, and amplitude) had a broad interindividual range of variation. A correlation between individual intraoperative changes in the potentials and surgical maneuvers or postoperative neurological deterioration was observed in eight cases. A spontaneous shift in latency greater than 15% or a sudden reduction in the amplitude of the potential greater than 80% was considered a warning criterion. In all cases in which there was an irreversible change in latency or a complete loss of potentials were observed, there was postoperative neurological deterioration. CONCLUSIONS: Improved surgical safety can be achieved using intraoperative neurophysiological monitoring procedures. Repetitive stimulation of the motor cortex proved to be a reliable method for monitoring subcortical motor pathways. Changes in MEP latency and MEP amplitude served as warning criteria during surgery and possessed prognostic value.

Adolescent↗
PubMed1997

Continuous electromyographic monitoring to detect nerve root injury during thoracolumbar scoliosis surgery.

STUDY DESIGN: The results of intraoperative monitoring during a case of nerve root injury sustained from scoliosis surgery to the thoracolumbar spine are described. OBJECTIVES: To improve the efficacy of intraoperative monitoring in preventing nerve root injury during scoliosis surgery. SUMMARY OF BACKGROUND DATA: Posterior tibial nerve somatosensory-evoked potentials are the electrophysiologic modality most commonly used for spinal cord monitoring during thoracolumbar spine surgery. Although radiculopathy is a more frequent postoperative complication than myelopathy, monitoring of mixed-nerve, somatosensory-evoked potentials may not detect injuries to individual nerve roots. METHODS: The patient described in this report developed left L5 radiculopathy after scoliosis surgery to the thoracolumbar spine. During surgery, intraoperative electromyographic monitoring identified frequent trains of neurotonic discharges in the left anterior tibial muscle. Bilateral, posterior, tibial nerve, somatosensory-evoked potentials remained normal. The left L5 nerve root was explored 9 days after the original surgery and was found to be compressed by bony structures. Electrophysiologic testing showed that the nerve root had undergone significant Wallerian degeneration, but remained in partial continuity. RESULTS: Nerve root injury was detected by neurotonic discharges identified during intraoperative electromyographic monitoring, but not by somatosensory-evoked potentials, which remained normal. When the injured nerve root was explored, a simple electromyographic technique was used to characterize the extent and type of injury. CONCLUSIONS: The authors of this study recommend electromyographic monitoring of appropriate lumbosacral myotomes in addition to somatosensory-evoked potentials during this type of procedure.

Adult↗
PubMed1999

Acoustic monitoring of intraoperative neuromuscular block.

Standard methods for accurate intraoperative measurement of neuromuscular block are either expensive or inconvenient and are not used widely. We have evaluated a new method of monitoring neuromuscular block using a low-frequency microphone. The method is based on the phenomenon of low-frequency sound emission by contracting skeletal muscle. Acoustic monitoring (MIC) with an air-coupled microphone was used to evaluate intraoperative neuromuscular block in 25 anaesthetized patients. The MIC recorded the response of the adductor pollicis muscle to supramaximal electrical stimulation of the ulnar nerve with train-of-four stimuli. The ratios of the first response (TI) to control (TC) were used for evaluation. Data obtained from the MIC were compared with simultaneous recordings, from the same hand, of mechanomyography (FDT), electromyography (EMG) and accelerography (ACC). Throughout the operative procedure, TI/TC ratios of the acoustic method correlated with the three reference devices: FDT, 12 patients, 262 data sets, r = 0.86, bias (%MIC-%FDT) = mean -5.3 (SD 19.6)%; EMG, 18 patients, 490 data sets, r = 0.85, bias (%MIC-%EMG) = -0.39 (20.29)%; and ACC, 13 patients, 328 data sets, r = 0.91, bias (%MIC-%ACC) = -3.0 (15.6)%. We conclude that monitoring intraoperative neuromuscular block by a microphone which transduces low-frequency muscle sounds is clinically feasible.

Adult↗
PubMed1987

Monitoring of cortical evoked potentials during surgical procedures on the cervical spine.

We reviewed the results of intraoperative monitoring of short-latency cortical evoked potentials in 81 patients who underwent surgical procedures of the cervical spine. Of these patients, 43 had baseline somatosensory evoked potentials from stimulation of the upper and lower extremities, intraoperative monitoring for at least 3 hours, and absence of an intrinsic lesion of the spinal cord. Major reductions in amplitude of the ulnar and tibial cortical evoked potentials occurred shortly after induction of anesthesia in 12% of patients. Latencies gradually increased during the operation as the concentration of volatile anesthetic agents increased. In patients with preoperative evidence of cervical cord damage, the cortical responses showed more fluctuations and could be lost without major changes in the concentration of the anesthetic agent or surgical manipulation. In one patient, intraoperative monitoring of the cervical cord function prevented a postoperative neurologic deficit. Ulnar and tibial cortical evoked potentials were successfully monitored throughout operation in all patients in whom baseline scalp responses could be obtained, but careful monitoring of anesthetic effect is necessary for proper interpretation.

Adult↗