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At least 703 records · Page 39Linked to original sources
PubMed2001

[Fast SEP measurement applied to intraoperative spinal cord monitoring].

Spinal cord monitoring techniques based on measuring somatosensory evoked potential (SEP) are presented. The principles and the experimental system for spinal cord monitoring are described in detail in the paper. The fast SEP measurement algorithm using pseudo-random sequence technique is also given. Experimental results show that our techniques can greatly improve the monitoring as compared to the traditional method, and further research in this connection is worth doing.

Algorithms↗
PubMed1996

New perspectives in intraoperative facial nerve monitoring with antidromic potentials.

Electromyographic (EMG) activity recorded from the facial muscles in response to electrical and mechanical stimulation is the most popular method for continuous monitoring of the facial nerve during cerebellopontine-angle surgery. EMG recording is, however, extremely sensitive to the administration of neuromuscular blockers. An alternative technique for the continuous monitoring of the facial nerve [i.e., monopolar recording of facial nerve antidromic potentials (FNAPs)], is described. Ten subjects undergoing retrosigmoid vestibular neurectomy for Meniere's disease and 11 subjects operated on with acoustic neuroma surgery via a retrosigmoid approach (tumor size range, 12-28 mm) participated in the investigation. Bipolar electrical stimulation of the marginalis mandibulae was performed to elicit FNAPs. Stimulus intensity ranged from 0 to 10 mA with a delivery rate of 7/s. Antidromic potentials were recorded with a silver-wire monopolar electrode positioned intracranially on the proximal portion (root entry zone) of the acoustic-facial bundle. Bipolar recordings with two silver electrodes were also performed from the trigeminal and facial nerves in the cerebellopontine angle to define the specific origin of the action potentials. FNAP amplitude increased as a function of stimulus intensity. The average latency was 3.35 ms (range, 3.0-3.7 ms). Action potentials recorded intracranially during electrical stimulation of the marginal nerve originated specifically from the facial nerve. Changes in latency and amplitude of FNAPs were analyzed as a function of the main surgical steps in patients operated on for acoustic neuroma. FNAP monitoring provided quantitative real-time information about damaging maneuvers performed on the nerve and postoperative facial function.

Adult↗
PubMed1996

Somatosensory evoked potential monitoring during carotid surgery.

Controversy exists over the value of intraoperative monitoring and shunting in patients undergoing carotid endarterectomy. Although it is widely believed that contralateral carotid occlusion and previous stroke mandate intraoperative shunting, the susceptibility of these two groups of patients to cerebral ischemia during carotid artery endarterectomy is not well defined. Somatosensory evoked potentials (SSEPs) were monitored in 113 carotid artery endarterectomy patients. Of these, 32 (28.3%) had a previous stroke, 24 (21.2%) had a contralateral carotid occlusion and 33 (29.2%) were diabetic. There were no deaths and only one perioperative stroke (0.9%). Cerebral ischemia occurred in 14 patients (12.4%). Six of these patients had a contralateral carotid occlusion. Some 29 patients (25.7%) were shunted, including 10 with contralateral carotid occlusions that did not have major SSEP changes. In the latter half of the study, 14 patients with contralateral carotid occlusions were selectively shunted (six shunted, eight not shunted) with no neurological complications. Thirty-two patients with prior strokes were selectively shunted (nine shunted, 23 not shunted); of these, one shunted patient undergoing combined carotid artery endarterectomy and coronary artery bypass grafting had a perioperative stroke. Intraoperative monitoring with SSEPs accurately identifies cerebral ischemia secondary to carotid clamping as well as patients requiring shunts. With use of intraoperative SSEP monitoring, selective shunting may be safely performed in patients with a contralateral carotid occlusion or a previous stroke.

Adult↗
PubMed1996

Validity and reliability of spinal cord monitoring in neuromuscular spinal deformity surgery.

Somatosensory evoked potentials (SSEPs) have become a standard of care in surgery for spinal deformity. Recent reports in the literature have suggested SSEP monitoring is not efficacious in surgeries for patients with neuromuscular disease. Electrophysiologic data were retrospectively analyzed from 74 patients with various neuromuscular disorders undergoing spinal-deformity surgery from 1989 through February 1995 at this medical center. The monitoring protocol included SSEPs recorded from multiple sites located cortically, subcortically, and peripherally. Neurogenic motor evoked potentials (NMEPs) were also employed. Anesthetic regimens were controlled for compatibility with evoked potential monitoring. Use of this intraoperative monitoring protocol resulted in reliable data for 95% of the patient population having baseline responses. Findings suggest that evoked potentials can be used effectively during surgery for neuromuscular spinal deformity. Use of a specific protocol allowed acquisition of reliable data intraoperatively, suggesting these methods are a valid means of monitoring neurologic status.

Adolescent↗
PubMed1993

Intraoperative facial nerve monitoring in acoustic neuroma surgery.

Intraoperative facial nerve monitoring simultaneously using electromyography and mechanical pressure sensors is being used in retrosigmoid and translabyrinthine approaches for acoustic neuroma resection. Insulated electrified microsurgical instruments and air drills are used to stimulate the facial nerve with a pulsed, constant current through bone and tumor, before the facial nerve is visually encountered. Electrical stimulation is used to help locate the facial nerve, map the course of the facial nerve within tumor, warn the surgeon of unexpected facial nerve locations, and help predict facial nerve function postoperatively. In 57 unmonitored cases a House-Brackmann (H-B) grade I or II result was obtained in 77 percent of small, 81 percent of medium, and 60 percent of large tumors. In 64 monitored cases H-B grade I or II was obtained in 88 percent of small, 79 percent of medium, and 90 percent of large tumors. Overall, facial nerve outcomes were better after monitored procedures (p < 0.02). A modified H-B classification for acute facial nerve injury is introduced to grade facial weakness immediately postoperatively and until function is stable at 1 year. In the unmonitored group there were five (9%) cases with a complete facial paralysis, facial nerve intact (i.e., acute H-B grade VIA) and seven (13%) cases with the facial nerve transected (i.e., acute H-B grade VIB). In the monitored group there were five (8%) acute H-B grade VIA and two (3%) acute H-B grade VIB results. In the unmonitored group of large tumors, there were statistically more patients with an acute H-B grade VIB result (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1999

Transcranial doppler detection of fat emboli.

BACKGROUND AND PURPOSE: The fat embolism syndrome (FES) is characterized by the simultaneous occurrence of pulmonary and neurological symptoms as well as skin and mucosal petechiae in the setting of long-bone fractures or their surgical repair. Its pathophysiology is poorly understood, and effective treatments are lacking. We present 5 patients with long-bone fractures in whom in vivo microembolism was detected by transcranial Doppler. METHODS: Five patients with long-bone fractures were monitored with transcranial Doppler for microembolic signals (MESs) after trauma. Two patients also had intraoperative monitoring. A TC-2020 instrument equipped with MES detection software was used. Detected signals were saved for subsequent review. Selected signals satisfied criteria defined previously and were categorized as large or small. RESULTS: Cerebral microembolism was detected in all 5 patients and was transient, resolving within 4 days of injury. Intraoperative monitoring revealed an increase in MESs during intramedullary nail insertion. The characteristics of MESs after injury varied among patients, with large signals being more frequent in the only patient with a patent foramen ovale. CONCLUSIONS: Cerebral microembolism after long-bone fractures can be detected in vivo and monitored over time. These findings may have potential diagnostic and therapeutic implications.

Accidents, Traffic↗
PubMedDate not supplied

[Anesthesiologic problems in hypothyroidism. Description of a clinical case].

The successful management of a case of primary hypothyroidism, who underwent hemicolectomy, is described. Anaesthesia was induced with TPS and maintained with only isoflurane. Neuromuscular blockade was achieved by atracurium. Hemodynamic, respiratory and neuromuscular monitoring was performed. This complex intraoperative monitoring allowed a quick recovery of the patient without any complications.

Anesthesia↗
PubMedDate not supplied

[Auditory brain stem potentials evoked by electrical stimulation of cochlear nuclei during central auditive implant setting].

INTRODUCTION: The implantation of a stimulator over the surface of the cochlear nuclei can provide a partial auditive capability to patients deaf due to a bilateral lesion of the 8th nerve. Intraoperative monitoring of short latency electrically-evoked potentials is useful to asses the correct positioning of the implant, specially when there are anatomical distortions. PATIENTS AND METHODS: Evoked potentials from two patients with type II neurofibromatosis were recorded during implantation surgery, using a blanker system to eliminate the stimulus artifact. RESULTS: In both cases, two-peak vertex-positive responses were obtained, with latencies between 0.4-0.5 and 1.2-1.4, respectively. This responses are similar to the most frequent response described. DISCUSSION: Intraoperative monitoring of electrically-evoked auditory brainstem responses is a useful technique to confirm the correct positioning of the cochlear stimulator. The study of the morphology of these responses can help to understand the mechanisms involved in the generation by the brainstem of the auditive evoked potentials. More experience on this subject is needed to establish a correlation between intraoperative results and postoperative stimulator function.

Adult↗
PubMed1986

Do we monitor enough? We don't monitor enough.

The choice of which intraoperative monitors to use for routine cases is difficult, because a multitude of monitors is available today. Monitoring is deemed necessary to avoid problems, although there is little hard evidence that a specific monitor will improve outcome. The risk associated with modern noninvasive monitors, however, is negligible, and they should be considered for routine use in all patients. Although errors in the variables displayed or misuse of correct information can cause difficulties, these result from a lack of education and are not a valid reason to abandon a particular monitoring modality. Regular use of such monitoring tools as the electroencephalogram would allow clinicians to become familiar with how to interpret it in normal and crisis situations. The cost of a disaster during anesthesia (such as unrecognized hypoxia) is high. The dollars spent to cover a single major malpractice award could buy a tremendous number of monitors. The state of the art in the mid-1980s demands traditional anesthesia monitors plus continuous capnography and measurement of peripheral oxygenation. Other negligible-risk monitors should also be used when feasible. Improvement in monitoring design, particularly in output formats and in integration of monitored data, will be essential in the next few years, as will training in the proper use of monitors.

Electrocardiography↗
PubMed1979

Activated clotting time (ACT) monitoring of intraoperative heparinization in peripheral vascular surgery.

We conclude that (1) the activated clotting time (ACT) is an accurate method of monitoring anti-coagulation during peripheral vascular surgery and can easily be performed by a technician in the operating room or at the bedside; (2) an initial heparinizing dose of 120 to 130 units/kg is adequate in 95 per cent of the patients; (3) the ACT should be maintained at greater than twice the control values (180 to 200 seconds), which required supplementation within 2 hours in 21 per cent; (4) the response to heparin is twofold: an initial sensitivity or resistance followed by an independent and variable rate of consumption; (5) the patient's heparin dose-response curve should be used to calculate the amount of supplemental heparin needed to maintain the ACT at a safe level; (6) protamine should be given if the ACT at the conclusion of the operation is greater than 150 seconds (50 per cent of our patients); and (7) a final ACT 15 to 30 minutes postoperatively should be obtained to ensure adequate reversal or to detect heparin rebound or depletion of clotting factors.

Arteries↗
PubMed1991

Intraoperative cranial nerve monitoring during posterior skull base surgery.

Intraoperative monitoring of neurophysiologic function is rapidly evolving as an important adjunct during skull base surgery to reduce the incidence of neurologic deficit. Facial nerve monitoring is an excellent model, since electrical and mechanical evoked potentials can be directly presented to the surgeon in real-time through an acoustic loudspeaker display. The lower cranial nerves may also be monitored using similar electromyographic techniques. Auditory system monitoring is more difficult due to the low amplitude response that requires averaging and filtering to extract the evoked potential. In conjunction with auditory monitoring, improved hearing preservation may be further enhanced by concomitant facial nerve monitoring, since the surgeon is alerted to traumatic manipulations that may affect both facial and cochlear nerves. Techniques and interpretative issues are presented to maximize the efficacy and safety of cranial nerve monitoring.

Journal Article↗
PubMed2002

[Reliabilty of intraoperative recurrent laryngeal nerve monitoring in thyroid surgery].

INTRODUCTION: The intraoperative monitoring of the recurrent laryngeal nerve (NLR) is increasingly used in thyroid surgery. What has the surgeon to know about reliability and peculiarity of this method? PATIENTS AND METHOD: Between 11/98 and 3/01 417 patients were operated for thyroid pathology. Vocal cord function was controlled pre- and postoperatively in all cases by laryngoscopy. Intraoperative electromygraphic NLR identification and postoperative vocal cord function were registered prospectively. RESULTS: Intraoperative NLR identification succeeded in 98.9 % (776/784 nerves at risk). Minor vocal cord dysfunctions were demonstrable for less than 4 weeks in 13 patients (1.6 %) associated with edema or hematoma in 11/13 cases. Complete unilateral NLR pareses was seen laryngoscopically in 16 patients (2 %). 1 patient revealed a malignant NLR infiltration. Electromygraphic NLR identification wasn't possible and followed by postoperative NLR palsy in 2 patients. In 11/13 cases with a regular intraoperative monitoring postoperative vocal cord function recovered within 8 weeks. In 2 of 4 NLR pareses persisting at the moment the follow up is longer than 12 months (permanent palsy rate 0.25 %). CONCLUSIONS: NLR identification during thyroid surgery is improved by intraoperative monitoring. In cases with difficult thyroid preparation the vagal nerve may be stimulated for indirect proof of NLR integrity.

Adult↗