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At least 613 records · Page 34Linked to original sources
PubMed2002

Intraoperative pathological monitorization of surgical margins: a method to reduce recurrences after conservative treatment for breast cancer.

INTRODUCTION: Local recurrences after conservative surgical treatment for breast cancer are not uncommon and cause negative influences on the oncological prognosis and quality of life of the patients. Aiming to avoid this problem, we have developed a method of intraoperative pathological monitoring of surgical margins (IPMSM), in order to assure adequacy of resection. MATERIALS AND METHODS: IPMSM is based on radiological. macroscopic, cytological and histological examination of frozen sections of the breast specimens in the operating room during the surgery. We evaluated 98 women with 100 tumors clinical stage I-II breast cancer for whom we planned conservative surgery. The margins were oriented by the surgeon and inked by the pathologist in different colors to retain orientation. RESULTS AND DISCUSSSION: According to the histological or cytological results, immediate re-excision was indicated and performed in 40 (40.8%) cases. In six of these, we had to perform a mastectomy. The indications for additional resections were: insufficient margins in 23 cases, extensive intraductal component in eight, multifocality in four, atypical proliferative lesion at the margin in four and diffuse tumor in one. Permanent histological sections confirmed all intraoperative results. These patients were followed by a median period of 42 months (range 3 to 99 months) and we observed 1% of local recurrence and 5.1% of distant metastasis. We compared this group of patients with a control group represented by 149 cases of breast cancer stages I-II treated by conservative surgery, but not submitted to IPMSM. In the control group, we observed 17 (11.4%) local recurrences and 49 (32.9%) distant metastases after a follow-up period from 14 to 213 months (median of 126 months). CONCLUSION: The IPMSM proved to be a safe and accurate method to prevent additional surgery for insufficient margins and to reduce the recurrence rate.

Adult↗
PubMed1993

A specialised computer-based monitoring system for intraoperative electrocorticography.

We have developed a computer-based intraoperative ECoG monitoring system which offers the flexibility of digital recording and allows detailed review of recorded events without interrupting monitoring. In addition, a diagram showing the electrode positions on the brain can be generated on computer screen and subsequently displayed during monitoring--this allows automatic indication of the electrode positions corresponding to specific ECoG channels and can provide the surgeon with a clear visual impression of the area of spiking.

Cerebral Cortex↗
PubMed1997

Continuous intraoperative electromyographic monitoring of cranial nerves during resection of fourth ventricular tumors in children.

The authors reviewed the results of continuous intraoperative electromyographic (EMG) monitoring of muscles innervated by cranial nerves in 17 children whose preoperative imaging studies showed compression or infiltration of the fourth ventricular floor by tumor to determine how intraoperative EMG activity correlated with postoperative cranial nerve morbidity. Bilateral lateral rectus (sixth) and facial (seventh) nerve musculatures were monitored in all children. Cranial nerve function was documented immediately postoperatively and at 1 year. Of the 68 nerves monitored, nine new neuropathies occurred in six children (sixth nerve in four children and seventh nerve in five). In five new neuropathies, intraoperative EMG activity could be correlated in one of four sixth nerve injuries and four of five seventh nerve injuries. Electromyographic activity could not be correlated in four children with new neuropathies. Of 59 cranial nerves monitored that remained unchanged, 47 had no EMG activity. Twelve cranial nerves (three sixth nerves and nine seventh nerves) had EMG activity but no deficit. Of four children with lateral rectus EMG activity, three had new seventh nerve injuries. Lateral rectus EMG activity did not predict postoperative abducens injury. The absence of lateral rectus EMG activity did not assure preserved abducens function postoperatively. Likely because of the close apposition of the intrapontine facial nerve to the abducens nucleus, lateral rectus EMG activity was highly predictive of seventh nerve injury. Although facial muscle EMG activity was not an absolute predictor of postoperative facial nerve dysfunction, the presence of facial muscle EMG activity was associated statistically with postoperative facial paresis. The absence of facial muscle EMG activity was rarely associated with facial nerve injury. The authors speculate that EMG activity in the facial muscles may have provided important intraoperative information to the surgeon so as to avoid facial nerve injury.

Adolescent↗
PubMed2002

[Does intraoperative nerve monitoring reduce the rate of recurrent nerve palsies during thyroid surgery?].

Two different aspects of the influence of neuromonitoring on the possible reduction of post-operative recurrent laryngeal nerve palsies require critical examination: the nerve identification and the monitoring of it's functions. Due to the additional information from the EMG signals, neuromonitoring is the best method for identifying the nerves as compared to visual identification alone. There are still no randomized studies available that compare the visual and electrophysiological recurrent laryngeal nerve detection in thyroid operations with respect to the postoperative nerve palsies. Nevertheless, comparisons with historical collectives show that a constant low nerve-palsy-rate was achieved with electrophysiological detection in comparison to visual detection. The rate of nerve identification is normally very high and amounts to 99 % in our own patients. The data obtained during the "Quality assurance of benign and malignant Goiter" study show that in hemithyreoidectomy and subtotal resection, lower nerve-palsy-rates are achieved with neuromonitoring as compared to solely visual detection. Following subtotal resection, this discrepancy becomes even statistically significant. While monitoring the nerve functions with the presently used neuromonitoring technique, it is possible to observe the EMG-signal remaining constant or decreasing in volume. Assuming that a constant neuromonitoring signal represents a normal vocal cord, our evaluation shows that there is a small percentage of false negative and positive results. Looking at the permanent recurrent nerve palsy rates, this method has a specificity of 98 %, a sensitivity of 100 %, a positive prognostic value of 10 %, and a negative prognostic value of 100 %. Although an altered neuromonitoring signal can be taken as a clear indication of eventual nerve damage, an absolutely reliable statement about the postoperative vocal cord function is presently not possible with intraoperative neuromonitoring.

Electromyography↗
PubMed2005

[Intraoperative neurophysiological monitoring of brain stem in a case of cavernoma in the pons].

Neurophysiological monitoring during surgery to avoid damaging of eloquent brain areas is a useful tool. We are performing intraoperative neurophysiological test to locate motor, sensitive and speech areas with cortical stimulation and cranial nerves during cerebellopontine cranial base surgery. Neurophysiological monitoring during brain stem surgery has been less described. Brain stem surgery implies a careful selection of patients for surgery given the high risk of morbidity and mortality. For this reason, conservative treatment is usually indicated when an asymptomatic cavernoma is incidentally found. Instead, when bleeding or neurological deficit appear, operative treatment may be indicated and then the goal of surgery is to avoid the disability linked to the natural history. We present the case of a 29 year old woman with diagnosis of multiple cavernomas. She was admitted at our hospital because she presented weakness and sensitive disturbance of left limbs and dizziness. The CT scan and MRI showed a pontine haemorrhage caused by a cavernous hemangioma. We operated her on using neurophysiological monitoring of VII, VIII, X and XII cranial nerves with electromyographic recordings. Postoperative disability could be reduced with a better knowledge of entry zone into the brain stem and early physiotherapy.

Adult↗
PubMed2000

Intraoperative duplex monitoring of infrainguinal vein bypass procedures.

PURPOSE: The purpose of this study was to evaluate intraoperative duplex scanning of infrainguinal vein bypass grafts to detect technical and hemodynamic problems, monitor their repair, and correlate findings with the incidence of thrombosis and stenosis repair rates within 90 days of operation. METHODS: Color duplex scanning was used at operation to assess vein/anastomotic patency and velocity spectra waveforms of 626 infrainguinal vein bypass grafts (in situ saphenous, 228 grafts; nonreversed translocated saphenous, 170 grafts; reversed saphenous, 147 grafts; alternative [arm, lesser saphenous], 81 grafts) to the popliteal (n = 267 grafts), infrageniculate (n = 323 grafts), or pedal artery (n = 36 grafts). The entire bypass graft was scanned after intragraft injection of papaverine hydrochloride (30-60 mg) to augment graft flow. Vein/anastomotic/artery segments with velocity spectra that indicate highly disturbed flow (peak systolic velocity, >180 cm/sec; spectral broadening; velocity ratio at site, >3) were revised. Grafts with a low peak systolic velocity less than 30 to 40 cm/s and high outflow resistance (absent diastolic flow) underwent procedures (distal arteriovenous fistula, sequential bypass grafting) to augment flow; if this was not possible, the grafts were treated with an antithrombotic regimen, including heparin, dextran, and antiplatelet therapy. RESULTS: Duplex scanning prompted revision of 104 lesions in 96 (15%) bypass grafts, including 82 vein/anastomotic stenoses, 17 vein segments with platelet thrombus, and 5 low-flow grafts. Revision rate was highest (P <.01) for alternative vein bypass grafts (27%) compared with the other grafting methods (reversed vein bypass grafts, 10%; nonreversed translocated, 13%; in situ, 16%). A normal intraoperative scan on initial imaging (n = 464 scans) or after revision (n = 67 scans) was associated with a 30-day thrombosis rate of 0.2% and a revision rate of 0.8% for duplex-detected stenosis (peak systolic velocity, >300 cm/s; velocity ratio, >3.5). By comparison, 20 of 95 bypass grafts (21%) with a residual (n = 29 grafts) or unrepaired duplex stenosis (n = 53 grafts) or low flow (n = 13 grafts) had a corrective procedure for graft thrombosis (n = eight grafts) or stenosis (n = 12 grafts; P <.001). Overall, 8% of patients with bypass grafts underwent a corrective procedure within 90 days of operation. Secondary graft patency was 99.4% at 30 days and 98.8% at 90 days (eight graft failures). CONCLUSION: The observed 15% intraoperative revision rate coupled with a low 90-day failure/revision rate (2.5%) for bypasses with normal papaverine-augmented duplex scans supports the routine use of this diagnostic modality to enhance the precision and early results of infrainguinal vein bypass procedures.

Anastomosis, Surgical↗
PubMed2004

Neurovascular decompression in trigeminal neuralgia: role of intraoperative neurophysiological monitoring in the learning period.

This paper deals with the first 45 consecutive patients undergoing microvascular decompression (MVD) surgery for trigeminal neuralgia, studied with perioperative brainstem auditory evoked potentials (BAEPs) and electromyography (EMG). We observed a good correlation between the intraoperative BAEP modifications and postoperative hearing function. BAEP monitoring was useful in identifying the manoeuvres that may compromise cochlear nerve function. This improved the surgical technique in the subsequent cases and reduced the incidence of iatrogenic hearing deficits after the learning period. There were no correlations between the entity of the intraoperative EMG discharges and the postoperative facial and trigeminal function. Intraoperative EMG monitoring can be useful during the period of learning as a means of identifying the different nerves in the cisternal tract.

Adult↗
PubMed2001

Hearing preservation in acoustic neuroma surgery.

This article reviews the Montreal experience of hearing preservation in acoustic neuroma surgery. The medical records since 1995 of 36 patients who underwent acoustic neuroma extirpation with the intent to preserve hearing were examined. Intraoperative monitoring was conducted using auditory brainstem response measurement with electrocochleography via a transtympanic electrode. The role of intraoperative monitoring in guiding surgical technique and its correlation with postoperative hearing outcome are discussed. A review of the literature regarding hearing preservation in acoustic neuroma surgery is included.

Adult↗
PubMed1996

Continuous intraoperative electromyographic monitoring of cranial nerves during resection of fourth ventricular tumors in children.

The authors reviewed the results of continuous intraoperative electromyographic (EMG) monitoring of muscles innervated by cranial nerves in 17 children whose preoperative imaging studies showed compression or infiltration of the fourth ventricular floor by tumor to determine how intraoperative EMG activity correlated with postoperative cranial nerve morbidity. Bilateral lateral rectus (sixth) and facial (seventh) nerve musculature were monitored in all children. Cranial nerve function was documented immediately postoperatively and at 1 year. Of the 68 nerves monitored, nine new neuropathies occurred in six children (sixth nerve in four children and seventh nerve in five). In five new neuropathies, intraoperative EMG activity could be correlated in one of four sixth nerve injuries and four of five seventh nerve injuries. Electromyographic activity could not be correlated in four children with new neuropathies. Of 59 cranial nerves monitored that remained unchanged, 47 had no EMG activity. Twelve cranial nerves (three sixth nerves and nine seventh nerves) had EMG activity but no deficit. Of four children with lateral rectus EMG activity, three had new seventh nerve injuries. Lateral rectus EMG activity did not predict postoperative abducens injury. The absence of lateral rectus EMG activity did not assure preserved abducens function postoperatively. Likely because of the close apposition of the intrapontine facial nerve to the abducens nucleus, lateral rectus EMG activity was highly predictive of seventh nerve injury. Although facial muscle EMG activity was not an absolute predictor of postoperative facial nerve dysfunction, the presence of facial muscle EMG activity was associated statistically with postoperative facial paresis. The absence of facial muscle EMG activity was rarely associated with facial nerve injury. The authors speculate that EMG activity in the facial muscles may have provided important intraoperative information to the surgeon so as to avoid facial nerve injury.

Journal Article↗
PubMed2002

An approach to intraoperative neurophysiologic monitoring of thoracoabdominal aneurysm surgery.

Thoracoabdominal aneurysm surgery carries an approximate 10% risk of intraoperative paraplegia. Abrupt cord ischemia and the confounding effects of systemic alterations and limb or cerebral ischemia challenges neurophysiologic spinal cord monitoring. This investigation sought a rapid differential monitoring approach to predict or help prevent paraplegia. Thirty-one patients were monitored with motor evoked potentials (MEPs) and median and tibial somatosensory evoked potentials (SSEPs). MEPs involved single-pulse transcranial electrical stimulation with D wave recording (n = 16), arm and leg muscle MEPs following multiple-pulse transcranial electrical stimulation (n = 12), or both (n = 3). D wave recordings required averaging, invasive epidural electrode insertion, and produced both false positives and false negatives. Muscle MEPs were instantaneous and reliably sensitive and specific for cord ischemia. Cortical and peripheral nerve SSEPs provided rapid detection of systemic alterations and cerebral or limb ischemia. Cord and subcortical SSEPs required excessive averaging time. In conclusion, bilateral arm and leg muscle MEPs with median and tibial peripheral nerve and cortical SSEPs provide sufficiently rapid detection and differentiation of cord ischemia from confounding factors. There were two predicted intraoperative spinal cord infarctions (6.5%) and nine circumstantial examples of possible contributions to deficit prevention.

Adult↗
PubMed1996

Evaluation of pedicle screw insertion monitored by intraoperative evoked electromyography.

The insertion of pedicle screws monitored by evoked electromyography (EMG) was prospectively evaluated in the 132 consecutive patients. The technique involved constant-voltage stimulation and was statistically evaluated at both the arbitrary 20- and 40-V settings. The patients were postoperatively evaluated clinically and radiographically. Computed tomography (CT) scanning was performed for new neurologic deficits. Results were divided into three groups: type 1, a negative EMG response; type 2, a positive EMG response, but no corrective action taken; and type 3, a positive EMG response and corrective action undertaken. Nonparametric statistics were used to evaluate the results at both the 20- and 40-V settings. In the type 3 group, in which corrective action was undertaken, there were no neurologic injuries or screw removals, a statistically significant result. Looking at the two intensity levels, at 20- and 40-V settings, there were no statistically significant differences in the three classifications at either intensity level. We concluded the evoked EMG for monitoring pedicle screw insertion is an efficacious adjunct. A positive response at < 20 V with the constant-voltage technique warrants corrective action.

Adult↗
PubMed1990

Intraoperative facial nerve monitoring. Technical aspects.

Intraoperative facial nerve monitoring (FNM) is widely used as a method of assessing the anatomic and physiologic integrity of the facial nerve during procedures in which the nerve may be in jeopardy. The doctors of the Otologic Medical Group use intraoperative FNM during all neurotologic procedures. This technique can also be used for congenital ear surgery and complicated revision chronic ear surgery. On the basis of experience gained from more than 200 cases in which FNM has been used, definitive conclusions can be made in regard to technical aspects. This article will discuss indications for intraoperative FNM, electrode design, visual and auditory feedback, and the particulars about stimulators.

Facial Nerve↗
PubMed1993

Effects of four intravenous anesthetic agents on motor evoked potentials elicited by magnetic transcranial stimulation.

The influence of four intravenous anesthetic agents on motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (magnetic MEP) was examined in 77 subjects. The patients were anesthetized by a continuous intravenous infusion of one of the following anesthetic agents: propofol, etomidate, methohexital, or thiopental. Comparable anesthetic effects among the four agents were achieved by computing an infusion scheme for each drug. Infusion rates were increased slowly in a step-wise manner in order to reach minimal anesthetic blood concentrations within 15 minutes. During anesthesia induction, magnetic MEPs were recorded every 2 minutes from the abductor pollicis brevis muscle. The patient's level of consciousness was assessed and documented in the alternating minutes. A dose-related reduction of the MEP amplitudes was seen in all drug groups, while the latencies remained constant. Reduction of the amplitude was occasionally so prominent that the MEP was completely abolished before adequate anesthesia was achieved. MEPs were obtainable at the end of anesthesia induction in 14% of the propofol group (n = 22), 57% of the etomidate group (n = 21), 53% of the methohexital group (n = 19), and 20% of the thiopental group (n = 15). Propofol and thiopental showed significantly stronger suppression of MEP, when compared to etomidate (both P < 0.01) and to methohexital (P = 0.01 and 0.05, respectively). Etomidate was the least detrimental anesthetic agent for intraoperative monitoring of magnetic MEP. Nonetheless, the low incidence of 57% of preserved MEP in subjects without motor deficits indicated the inadequacy of this technique for intraoperative monitoring. More effective transcranial stimulation techniques are required for successful intraoperative MEP monitoring.

Adult↗
PubMed2000

[Intraoperative neurophysiological monitoring (IONM) of the recurrent laryngeal nerve and microdissection. Surgical techniques for decreasing the risk of recurrent laryngeal nerve paralysis].

BACKGROUND: Frequently numerous recurrent laryngeal nerve injuries occur after operations on the thyroid glands. Compared with postoperative permanent hypocalcemia, unilateral and especially double-side recurrent paresis pose serious complication. As early as 1938 specialists [1] pleaded for a routine visualisation of the nervus recurrens in operations of the thyroid gland, to reduce the risk of permanently recurring paresis. In controversial discussions of the matter specialists have opted for a demonstration of the nerve also under medico-legal aspects. Implementing functionally-critical operational strategies requires the choice of an anatomically suitable operative procedure for the removal of morphological, functional and oncological changes, as well as the avoidance of complications. METHOD: Intra-operative Monitoring is highly recommendable as a neurophysiological method of supervision combined with microdissection to ensure the safe handling of recurrent laryngeal nerve. CONCLUSION: The rate of permanent paresis on the recurrent nerve can be lowered to less than 1 per cent when this is used as a routine procedure for all operations and the treatment of the thyroid gland diseases.

Electric Stimulation↗
PubMed1987

Carotid endarterectomy without indwelling shunts and intraoperative electrophysiologic monitoring.

Although carotid endarterectomy is a common surgical procedure in North America, controversies exist regarding the type of anesthesia, the use of indwelling shunts and the need for intraoperative cerebral monitoring. We present a prospective study of 100 carotid endarterectomies performed over a three year period by a single surgeon without the use of indwelling shunts, patch grafts, or EEG monitoring. The combined stroke and mortality rate was 1%. Our results confirm those of other authors; that indwelling shunts and EEG monitoring are not absolutely essential for a satisfactory outcome in carotid endarterectomies.

Aged↗
PubMed1992

The case for routine intraoperative ECG monitoring.

Monitoring of the ECG is not advocated as the sole means of assessing cardiovascular function, but it does play an essential role in the diagnosis of intraoperative arrhythmias and does alert the anesthesiologist to potentially serious problems, which may otherwise go unrecognized.

Animals↗
PubMed1995

A prospective analysis of intraoperative electromyographic monitoring of pedicle screw placement with computed tomographic scan confirmation.

STUDY DESIGN: In a prospective study of 90 patients undergoing lumbar pedicle screw instrumentation, 512 screws were tested intraoperatively using electrical stimulation. The accuracy of this technique was verified after surgery by computed tomography. OBJECTIVES: Computed tomographic scans taken after surgery were used to evaluate the efficacy of intraoperative screw stimulation and electromyographic monitoring of pedicle screw placement. SUMMARY OF BACKGROUND DATA: Previous cadaveric and clinical studies showed the risk of pedicle screw malposition and the inadequate reliability of intraoperative radiographs to identify misplaced screws. METHODS: Screws (total, 512) in 90 patients were stimulated intraoperatively, and stimulation threshold was recorded. Computed tomographic scans were taken after surgery to document pedicle screw position. Electromyographic thresholds and computed tomographic data were evaluated independently and compared to assess the accuracy of the electromyographic screw stimulation technique. RESULTS: Intraoperative screw stimulation was extremely accurate in confirming the adequacy of screw position. A stimulation threshold greater than 15 mA provided a 98% confidence that the screw was within the pedicle. In eight of 90 patients (9%), electromyographic monitoring detected a screw malposition that was not identified on lateral radiograph. CONCLUSIONS: Screw stimulation monitoring is a valuable and efficacious adjunct to lumbar pedicle screw instrumentation. A stimulation threshold greater than 15 mA reliably indicates adequate screw position. A stimulation threshold between 10 and 15 mA was generally associated with adequate screw position, although exploration of the pedicle is recommended. A stimulation threshold less than 10 mA was associated with a significant cortical perforation in most instances.

Bone Screws↗