SEARCH · PubMed Health

Results for “Monitoring, Intraoperative”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources

PubMed1998

[Intraoperative monitoring of the function of the peroneal nerve in knee joint operations].

Operations on the knee are known to be associated with postoperative neurological complications. There is no consensus opinion on the causes of these complications. The aim of the present study was to develop a method for the intraoperative monitoring of the function of the common peroneal nerve. This was done as to identify intraoperative factors that might be responsible for reversible and irreversible neurological deficits. Computer-aided neuromonitoring is based on online digitizing of the surface EMG of the anterior tibial muscle. An algorithm continuously modifies the amplitude to determine the motor threshold. The method described has been used in 18 patients undergoing high tibial osteotomy. In 10 of the 18 patients, the nerve is rendered completely non-excitable after an average tourniquet application time of 59 min. This non-excitability was reversed on release of the tourniquet. In the remaining 8 patients, excitability was maintained throughout the ischaemic period, which did not exceed 60 minutes in any of the cases. Our method enables accurate quantification of the neural function throughout the entire operation, and convincingly documents the influence of ischaemia on peripheral nerve block.

Electromyography↗

PubMed1996

[Intraoperative monitoring of the recurrent laryngeal nerve. A new method].

Injury of the recurrent laryngeal nerve (RLN) is one of the most frequent complications in thyroid surgery. It leads to a significant morbidity of up to 20%, depending on the type of surgery being performed. We present a new device for intraoperative monitoring of the RLN. The new monitoring system was evaluated in piglets. The system is reliable and easy to use. For the first time even imminent injury to the RLN can undoubtedly be demonstrated by signal changes. It will soon be available for use in humans.

Animals↗

PubMed1987

Intraoperative monitoring with somatosensory evoked potentials in neurosurgical operations on the spinal cord.

Our report deals with 24 patients who were treated neurosurgically for spinal space occupying lesions and in whom a noninvasive technique of intraoperative monitoring with somatosensory evoked potentials (SEP) was carried out. Reproducible potentials were obtained intraoperatively in each case, but only patients in whom potentials could be obtained preoperatively were included in the study. Using changes in amplitudes of up to 50% of the starting value as criteria, it was possible to make an accurate statement as to the expected postoperative neurological status in 22 patients (91.7%). We found false positive results in 2 cases (8.3%), but no false negative results were observed. In one patient, a postoperative complication caused by bleeding could be discovered in the early stages by means of postoperative SEP-monitoring. The results confirm the reliability and usefulness of this noninvasive technique when applied intraoperatively. Furthermore, the value of SEP-monitoring during the early postoperative phase in cases where the clinical judgment is limited due to anesthesia is emphasized. The secondary postoperative deterioration in the neurological status of one patient with a ventral space occupying lesion could not, however, be detected with the SEP monitoring. The use of the motor stimulation technique could be an advantageous adjunct in intraoperative and perioperative monitoring, particularly in cases where primarily motor pathways are at risk.

Adolescent↗

PubMed1992

Intraoperative monitoring of facial and cochlear nerves during acoustic neuroma surgery.

The likelihood of successful preservation of facial and cochlear nerve function during acoustic neuroma surgery has been improved by the advent of intraoperative monitoring techniques. The facial nerve is monitored by recording EMG from facial muscles, with no muscle relaxants used; mechanical irritation of the nerve during surgery causes increased EMG activity, which can be detected in real time using a loudspeaker. Brief episodes of activity associated with specific surgical maneuvers aid the surgeon in avoiding damage to the nerve, whereas prolonged tonic EMG activity may reflect significant neural injury. Electrical stimulation with a hand-held probe elicits evoked EMG responses, which can be used to locate and map the nerve in relation to the tumor. The threshold for eliciting evoked EMG responses provides a rough indicator of the functional status of the nerve. Different nerves in the posterior fossa (trigeminal, facial, spinal accessory) can be identified in multichannel recordings by the spatial distribution and latency of responses to electrical stimulation. The ability to elicit EMG responses from low amplitude stimulation of the facial nerve at the brain stem after tumor removal is a reasonable predictor of postoperative facial function. Cochlear nerve function is assessed by recording the ABR from ear canal and scalp electrodes or the CNAP with an electrode placed directly on the nerve at the brain stem root entry zone. The ABR is a well-known, noninvasive technique that can be adapted to intraoperative use relatively easily but is of limited utility owing to the delay inherent in signal averaging. Direct CNAP recordings require placement of an intracranial electrode in such a way as to contact the cochlear nerve without interfering with surgical access but have the distinct advantage of rapid feedback on changes in cochlear nerve status.

Cochlear Nerve↗

PubMed2001

Individually optimizing posterior tibial somatosensory evoked potential P37 scalp derivations for intraoperative monitoring.

This investigation sought the optimal (highest amplitude) derivation for monitoring the posterior tibial P37 for each side in each individual, and determined whether this may change intraoperatively. Fifty monitored patients were studied using a partial P37 map consisting of FPz, Fz, Cz, Cz', Pz, POz, C4', and C3' to a noncephalic reference. From this, the highest amplitude scalp derivation was determined for each side. Of 100 tibial nerves, the initial optimal input 1 was Cz' in 52%, Pz in 28%, and Cz or iC' in 10%, and optimal input 2 was cC' in 69% and FPz in 31%. The optimal derivation was the same for each side in 34% of patients and different in 66%. Of 31 patients with at least one subsequent trial later during surgery, P37 topography changed in 14 and affected optimal inputs in 12. This occurred regularly during sitting-position posterior fossa surgery because of intracranial air, but sometimes occurred during other surgeries as well. The most common change consisted of FPz replacing cC' as optimal input 2. Input 1 changes were predominantly in an anterior or posterior sagittal direction. The results demonstrate great inter- and intraindividual P37 variability, and document intraoperative topographic changes. Both phenomena can be addressed by a practical method to refine intraoperative monitoring by individually optimizing scalp derivations and identifying topographic P37 changes during surgery.

Evoked Potentials, Somatosensory↗

PubMed1995

[Intraoperative monitoring of the lower cranial nerves during skull base surgery: evoked electromyographic technique].

Functional preservation of the lower cranial nerves is an important issue in the surgery of the skull base to avoid postoperative serious complications such as aspiration pneumonia and respiratory disorders. We presented our experience of intraoperative monitoring of the lower cranial nerves during skull base surgery. The evoked electromyographic (EMG) activities were successfully recorded from the muscles innervated by the lower cranial nerves. These EMG recordings are helpful to guide the surgeon intraoperatively and to avoid careless severing of these nerves. Although the glossopharyngeal nerve that innervates only one small muscle in the pharynx (M. stylopharyngeus) cannot be monitored with the evoked EMG technique described in this paper, the position of this nerve can be deduced from the position of the vagus nerve.

Adult↗

PubMed2001

Remifentanil- and fentanyl-based anesthesia for intraoperative monitoring of somatosensory evoked potentials.

We sought to compare effects of remifentanil- and fentanyl-based anesthesia on the morphology of somatosensory evoked potentials (SSEPs) and speed of recovery from anesthesia. Forty-one patients undergoing spinal surgery and requiring intraoperative monitoring of SSEPs were randomized into two groups. In Group 1, anesthesia was induced with sodium thiopental and maintained with fentanyl, 50% nitrous oxide in oxygen, and 0.5%--0.75% isoflurane. In Group 2, anesthesia was induced with sodium thiopental and maintained with remifentanil, 50% oxygen in air, and 0.5%--0.75% isoflurane. The variables compared included hemodynamic changes during the induction and intubation, the interval from the end of anesthesia to extubation, intraoperative blood loss and fluid administration, and changes in latency and amplitude of the P37--N45 component of posterior tibial nerve somatosensory evoked potentials and the N20--P24 component of median nerve somatosensory evoked potentials. The two groups were matched for demographics, ASA physical status, and duration of surgery. Hemodynamic profiles after the induction and intubation were similar. There were significant differences between groups in time intervals from the end of anesthesia to extubation (15.3 +/- 12.8 vs 5.3 +/- 2.3 min; P = 0.0001) and ability to follow verbal commands (14.6 +/- 11.9 vs 4.5 +/- 2.4 min; P = 0.0001), with the Remifentanil group showing earlier recovery. Variability (coefficient of variation) of P37--N45 latency was greater (0.026 vs 0.014; P = 0.001) in the Fentanyl group.

Adult↗

PubMed1998

Intraoperative monitoring and postoperative imaging of hepatic cryosurgery.

Because intraoperative sonography displays segmental anatomy, allows discovery of more lesions than previously suspected from preoperative imaging, surgical inspection, or palpation, and permits more certain diagnosis of problematic masses, it facilitates surgical decision-making when liver resection or cryoablation is anticipated. Intraoperative sonography provides a guidance modality to accurately place cryosurgery probes in liver masses. More precise treatment of metastatic and primary tumors of the liver is possible with cryoablation because intraoperative sonography provides a means of monitoring the growth of the enlarging freeze zone to insure adequate surgical margins. Postoperative detection of acute complications after cryosurgery is best done with computed tomography. Normally cryosurgery defects shrink with time and lose the peripheral contrast opacification seen after surgery. Gas collections, seen as a result of tissue necrosis, must be discriminated from infection. Tumor recurrence can be detected well with computed tomography or magnetic resonance imaging following hepatic cryosurgery.

Carcinoma, Hepatocellular↗

PubMedDate not supplied

A new technique for intraoperative monitoring of spinal cord function: multichannel recording of spinal cord and subcortical evoked potentials.

A new technique for intraoperative monitoring of spinal cord function is described. Evoked potentials to peripheral nerve stimulation are recorded with interspinous ligament needles from below and from two or more levels above the surgery. Simultaneously subcortical potentials are recorded with scalp electrodes from cervical-scalp derivations. Simultaneous recordings from multiple levels (below and above the surgical procedure) permit reliable differentiation between technical problems and alteration of cord function due to the surgical procedure. The interspinous ligament technique for recording of spinal potentials has significant advantages over previous monitoring techniques. One case in which monitoring during surgery detected a reversible acute spinal cord dysfunction is described.

Adolescent↗

PubMedDate not supplied

Excision of a mediastinal parathyroid gland with use of video-assisted thoracoscopy, intraoperative 99mTc-sestamibi scanning, and intraoperative monitoring of intact parathyroid hormone.

OBJECTIVE: To report the complementary use of video-assisted thoracoscopic surgery (VATS) and intraoperative 99mTc-sestamibi scanning for persistent secondary hyperparathyroidism due to a mediastinal supernumerary parathyroid gland. METHODS: We describe a patient with recurrent secondary hyperparathyroidism attributable to a mediastinal parathyroid gland who underwent parathyroidectomy with use of VATS, intraoperative 99mTc-sestamibi scanning (gamma probe), and intraoperative monitoring of intact parathyroid hormone (iPTH). RESULTS: A 32-year-old man with chronic renal failure who had undergone a 4-gland parathyroidectomy with autotransplantation 14 years previously presented with symptomatic hypercalcemia. A preoperative single-photon emission computed tomographic (SPECT) sestamibi scan revealed a focus of mediastinal uptake, suggestive of an intrathymic gland. The patient underwent a cervical exploration, and the previously reimplanted parathyroid gland and the thymus were resected. iPTH levels failed to normalize, and the operation was terminated. A repeated SPECT scan again revealed an area of mediastinal uptake. Computed tomographic scan of the chest showed a mediastinal gland adjacent to the aortic arch. VATS and intra-operative sestamibi scanning aided in localization of the ectopic parathyroid gland. After removal of the hyperplastic gland, iPTH levels decreased appropriately. CONCLUSION: In reoperative parathyroidectomy involving mediastinal glands, VATS, complemented by gamma probe localization and iPTH monitoring, may be used to minimize the operative dissection needed to cure hyperparathyroidism.

Adult↗

PubMed2003

Intraoperative monitoring and facial nerve outcomes after vestibular schwannoma resection.

OBJECTIVE: To determine the predictive value of proximal facial nerve electrical threshold and proximal-to-distal facial muscle compound action potential amplitude ratio on facial nerve outcomes after resection of vestibular schwannomas. STUDY DESIGN: Retrospective case review. SETTING: Tertiary care hospital. PATIENTS: Two hundred twenty-nine patients undergoing resection of vestibular schwannomas with intraoperative facial nerve monitoring at a single institution. INTERVENTION: All patients underwent resection of vestibular schwannomas with the use of intraoperative monitoring. MAIN OUTCOME MEASURE: Facial nerve function was classified according to the House-Brackmann scale at the patient's last office follow-up. Last follow-up was at least 6 months after surgery. RESULTS: Good facial nerve function (House-Brackmann Grade I or II) was observed in 87% of the patients at their last office follow-up. Proximal-to-distal amplitude ratio and proximal electric threshold were statistically significant in predicting facial nerve outcome. A mathematical model predicting the probability of good outcome on the basis of the intraoperative parameters is presented. CONCLUSION: Intraoperative monitoring has significantly decreased facial nerve morbidity in vestibular schwannoma surgery. Despite the advances in surgery and monitoring, a group of patients still have poor facial nerve outcomes. The use of intraoperative nerve monitoring may be able to predict poor long-term facial nerve outcomes and thus modify the timing of rehabilitation.

Action Potentials↗

PubMed2001

Intraoperative monitoring of the bulbocavernosus reflex: the method and its problems.

OBJECTIVES: This study evaluates the method of intraoperative neurophysiological monitoring of the bulbocavemosus reflex (BCR) with reference to stimulation and detection. METHODS: The study was performed on a group of 65 patients, 53 men and 12 women, who underwent surgery for lower thoracic and lumbar spinal trauma, with no neurological deficit prior to or following surgery. Stimulating electrodes were placed on the dorsum of the penis or the clitoris. Single and double stimuli were used, as well as trains of 3, 4 and 5 stimuli. Detecting wire electrodes were introduced into the perianal region. RESULTS: A single stimulus elicited the BCR in 50%, pairs in 75%, trains of 3 in 95%, and trains of 4 and 5 in 100% of patients. With placement of the detecting electrodes 2.5 cm deep to the skin, the BCR was detected in 13% of hemisphincters in women, and in 81% of hemisphincters in men. With controlled intramuscular placement of detecting electrodes, the BCR was detected in 97% of hemisphincters in men. With bifocal detection the BCR amplitudes were 30-312 mV (median 90), and interside amplitude ratio was 0.05-1 (median 0.66); with monofocal detection, amplitudes and interside amplitude ratio were 30-560 mV (median 200) and 0.15-1 (median 0.86), respectively. CONCLUSIONS: A train of 4 electrical stimuli is optimal in eliciting the BCR in anesthetized patients. The low rate of elicitability in women was most probably due to inefficient stimulation. Detection was improved by controlled intramuscular placement of electrodes. Monofocal detection yielded higher BCR amplitudes. Interside difference and interindividual variability of the BCR amplitude were considerable.

Adolescent↗

PubMedDate not supplied

Intraoperative monitoring in selective dorsal rhizotomy.

The method used in the intraoperative portion of the selective dorsal rhizotomy procedure for the selection of abnormal circuits within the central nervous system of children with spasticity due to cerebral palsy is described. The decision to transect dorsal rootlets is made on the basis of electrophysiological, behavioral and medical criteria. In 100 cases the average number of rootlets transected was 64%. Of the total stimulated, 23.3% exhibited normal electrophysiological and behavioral responses. Decision making regarding the preservation or transection of the remaining 12.7% of the segments is described. This information is presented in an effort to increase understanding of this particular portion of the procedure and to encourage standardization of the procedure between centers in the future.

Child↗

PubMed1990

Modification to a commercial immunoradiometric assay permitting intraoperative monitoring of parathyroid hormone levels.

We describe a modification to a commercially available immunoradiometric assay which reduces the turnaround time for parathyroid hormone (PTH) measurement to 1 h and permits intraoperative monitoring during parathyroidectomy. Alterations in PTH concentrations following removal of parathyroid tissue are compared with those of calcium, ionised calcium and phosphate. PTH measurements obtained intraoperatively permit definitive conclusions about the success of the operation within 1 h of sampling, allowing re-exploitation of the gland to take place immediately if necessary.

Calcium↗

PubMed1996

A trend-detection algorithm for intraoperative EEG monitoring.

Intraoperative EEG-monitoring needs to discriminate random fluctuations from real systematic variations (trends). This task is made more difficult by several types of artifacts. With the goal of supporting visual EEG evaluation, a new trend-detection algorithm is presented which is based on spectral analysis and a post-processing dynamic linear model, the latter introduced by Harrison and Stevens. A gradient value provided by this model is exploited to determine the onset and relative extent of an existing trend. Artifacts are detected by several threshold measures for the original signal and its first derivative. The system was validated using a set of intraoperative EEGs recorded during carotid endarterectomy.

Algorithms↗

PubMed1981

Early somatosensory potentials evoked by median nerve stimulation: intraoperative monitoring.

We identified the sites of origin of the somatosensory evoked potentials to median nerve stimulation by recording directly from the cervical cord in the course of intraoperative monitoring. The N9 potential occurred before any potentials recorded from the cord or dorsal roots. Potentials with latencies corresponding to N11 were recorded at the median nerve root entry zone of the lower cervical cord. High-amplitude potentials were recorded at the level of the foramen magnum, with latencies approximating or following P13, suggesting that this potential is generated at the cervicomedullary junction.

Electric Stimulation↗

PubMed1987

Brainstem auditory evoked potentials: intraoperative monitoring technique in surgery of posterior fossa tumors.

Brainstem auditory evoked potentials (BAEPs) were used to monitor eight neurosurgical procedures involving posterior fossa tumors to assist the neurosurgeon in preservation of hearing postoperatively. The technique included placement of recording electrodes over the Cz (vertex) and both earlobes. Stimulation was accomplished intraoperatively with a specifically designed intraauricular click stimulator that did not interfere with surgical access to the suboccipital region. Continuous BAEP recording was performed with particular attention to the sequence of preincision, opening of the dura, tumor mobilization, tumor excision, and closure. Absolute latencies and interpeak latencies of all five waves were recorded when possible. In three patients BAEPs were not significantly altered intraoperatively, and hearing was preserved postoperatively. In another three patients the acoustic nerve was severed during surgery and intraoperative monitoring was discontinued. In the remaining two patients medical complications arose intraoperatively, and significant irreversible changes in BAEP were observed despite no gross anatomical damage to the acoustic nerve. Both of these patients experienced postoperative hearing loss. These two cases illustrated some of the BAEP abnormalities that occurred during surgery. Difficulties during the procedures included electrical noise and interference, use of a bipolar cautery device, and unclear wave forms. Solutions for these difficulties were braiding the electrodes and using extra ground electrodes and a spike suppressor; switching off the evoked potential equipment when the bipolar cautery device was in use; and increasing repetitions and changing click intensity and polarity, respectively. Monitoring BAEPs in posterior fossa surgery can be accomplished with presently available equipment and may aid the neurosurgeon in preserving or minimizing injury to auditory pathways and adjacent structures.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2006

Intraoperative monitoring of segmental spinal nerve root function with free-run and electrically-triggered electromyography and spinal cord function with reflexes and F-responses. A position statement by the American Society of Neurophysiological Monitoring.

BACKGROUND CONTEXT: Orthodromic ascending somatosensory evoked potentials and antidromic descending neurogenic somatosensory evoked potentials monitor spinal cord sensory function. Transcranial motor stimulation monitors spinal cord motor function but only activates 4-5% of the motor units innervating a muscle. Therefore, 95-96% of the motor spinal cord systems activating the motor units are not monitored. To provide more comprehensive monitoring, 11 techniques have been developed to monitor motor nerve root and spinal cord motor function. These techniques include: 1. neuromuscular junction monitoring, 2. recording free-run electromyography (EMG) for monitoring segmental spinal nerve root function, 3. electrical stimulation to help determine the correct placement of pedicle screws, 4. electrical impedance testing to help determine the correct placement of pedicle screws, 5. electrical stimulation of motor spinal nerve roots, 6. electrical stimulation to help determine the correct placement of iliosacral screws, 7. recording H-reflexes, 8. recording F-responses, 9. recording the sacral reflex, 10. recording intralimb and interlimb reflexes and 11. recording monosynaptic and polysynaptic reflexes during dorsal root rhizotomy. OBJECTIVE: This paper is the position statement of the American Society of Neurophysiological Monitoring. It is the practice guideline for the intraoperative use of these 11 techniques. METHODS: This statement is based on information presented at scientific meetings, published in the current scientific and clinical literature, and presented in previously-published guidelines and position statements of various clinical societies. RESULTS: These 11 techniques when used in conjunction with somatosensory and transcranial motor evoked potentials provide a multiple-systems approach to spinal cord and nerve root monitoring. CONCLUSIONS: The techniques reviewed in this paper may be helpful to those wishing to incorporate these techniques into their monitoring program.

Electromyography↗