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At least 217 records · Page 12Linked to original sources

PubMed2006

Transcricothyroid, intraoperative monitoring of the vagus nerve.

OBJECTIVE: To develop a reliable, user-friendly, intraoperative, electromyographic monitoring technique to decrease the incidence of injury to the recurrent and superior laryngeal nerves. DESIGN: Prospective, nonrandomized, clinical trial of a nerve monitoring technique. SETTING: Private tertiary care community hospital. PATIENTS: A population-based sample of 31 patients scheduled to undergo thyroid surgery was enrolled consecutively. Included in the study were patients older than 18 years who were scheduled for surgery and who were able to provide informed consent. Exclusion criteria were pregnancy, implanted metallic devices, and history of laryngeal surgery, injury, paresis, hoarseness, or paralysis. No patients were excluded, and all completed the study and returned for follow-up visits. INTERVENTIONS: Twenty-nine patients required total thyroidectomy, of which 10 involved malignancy, and the other 2 patients required lobectomy. Each patient completed the Voice Handicap Index and underwent a preoperative fiberoptic laryngeal examination. Continuous monitoring was performed using a widely available, commercial nerve integrity monitor and a paired electrode placed into the cricothyroid space under direct vision. Postoperatively, participants completed a follow-up Voice Handicap Index survey and underwent a laryngeal examination. MAIN OUTCOME MEASURES: The incidence of vocal paresis, or paralysis, and the preoperative and postoperative voice handicap score were recorded. The usefulness of the device based on the surgeon's subjective and immediate postoperative impressions was rated on a visual analog scale. RESULTS: Sixty-two recurrent laryngeal nerves were identified with continuous electromyographic monitoring. Vocal cord paresis or paralysis was not observed. Postoperative Voice Handicap Index scores were unchanged from preoperative assessment. The technique was given a rating of 1 (most useful) on a 5-point scale in 70% of cases. CONCLUSIONS: The technique described is sensitive, easy to use, accurate, and associated with a high degree of surgeon satisfaction. This technique is not associated with additional risk to the patient and offers the potential to reduce injury. Monitoring provides assurance that the nerve is intact and functioning prior to extubation.

Adolescent↗

PubMed1982

Intraoperative monitoring of evoked potentials.

Sensory EPs were recorded intraoperatively in 173 neurosurgical procedures (71 VEPs, 66 BAEPs, and 31 SSEPs) to evaluate the utility of this technique. EPs could be safely recorded in all cases, but the yield of useful results varied with each sensory modality. BAEPs were recorded reliably in 100% of the cases and intraoperative latency changes accurately predicted postoperative hearing deficits in 10%. Potential hearing deficits were detected in another 15%. BAEP changes were associated with brainstem dysfunction in only one case. VEP changes were difficult to interpret intraoperatively because of contamination by a high degree of variability and both false negative and false positive results. Changes in VEP amplitudes related to surgical manipulation of the optic chiasm were only suggested. SSEP changes were recorded reliably in only 75% of the cases and no correlations between SSEP changes and postoperative sensory function were established. Again, intraoperative amplitude attenuation of the SSEP waveform with surgical manipulation only suggested a potential sensory deficit. Intraoperative EP monitoring is a valuable technique that provides a functional analysis of the sensory nervous system during surgical procedures. Specific sensory stimuli and improved data analysis will increase the utility of this CNS monitor.

Acoustic Stimulation↗

PubMed1986

[Technical problems in intraoperative monitoring of sensory evoked potentials].

Recent advances in both the equipment and the recording technique of sensory evoked potentials (EP) have brought high levels of versatility and reliability of objective measurement to the assessment of nervous system function. They have also allowed the use of intraoperative evoked potentials. The operating room, however, is usually considered a hostile environment, where various kinds of artifacts from surgical manipulation and generated by electrical armamentaria disturb electrophysiological recordings. Although several authors have reported on intraoperative EP monitoring, they have described few of the practical details of recording techniques. Having developed an intraoperative recording technique for evoked potentials over the past 3 years, we present the technical measures taken to overcome interference and obtain sufficiently stable and reliable EP recordings for intraoperative monitoring. All electrical equipment used in the operating rooms must, of course, be grounded securely. Even after grounding in the usual manner, however, artifacts appeared intermittently. The source was found to be a Mayfield-Kees three-pin head rest and a self-retaining retractor, both of which seemed to pick up electromagnetic radiation originating from electrocauteries and others. These artifacts could be minimized by grounding the head pins all each point of insertion into the patient's head and by use of a silicon-coated spatula rather than a metal one. In addition automatic artifact rejection by voltage overload sensing seems to be indispensable to eliminate the effect of extraneous mechanical and electrical interference which occur inevitably in surgical procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Stem↗

PubMed2005

Intraoperative monitoring using somatosensory evoked potentials. A position statement by the American Society of Neurophysiological Monitoring.

OBJECTIVE: To provide an educational service to the intraoperative neurophysiologist community by publishing a position statement by the American Society of Neurophysiological Monitoring on the recommended appropriate and correct use of somatosensory evoked potentials as an intraoperative neurophysiological monitoring tool to protect patient well-being during surgery. This position statement presents the somatosensory evoked potential utilization basis, relevant anatomy, patient preparation, important systemic factors, anesthesia considerations, safety and technical considerations, documentation requirements, neurophysiologist credentials and staffing practice patterns, and monitoring applications for protecting brain, spinal nerve root, peripheral nerve, plexus and spinal cord function. In conclusion, a summary of major recommendations regarding the use of somatosensory evoked potentials in intraoperative neurophysiological monitoring is presented.

Electric Stimulation↗

PubMed1978

Noninvasive intraoperative monitoring: a prospective study comparing Doppler systolic occlusion pressure and segmental plethysmography.

Seventy-two limbs in forty patients underwent Doppler systolic ankle pressure and Pulse Volume Recording (PVR) amplitude measurements intraoperatively. Control patients and patients undergoing abdominal aortic aneurysm (AAA) resections showed no significant decrease in Doppler systolic ankle/brachial pressure ratio (DSAB). PVR measurements were slightly decreased after declamping in the AAA patients. Femoropopliteal bypass was associated with a prompt increase in PVR and DSAB levels. In contrast, postreconstruction values in the extraanatomic (EA) and aortofemoral (AF) bypass groups were dependent upon the patency of the femoropopliteal segment. Intraoperative monitoring provides a quantitative assessment of the immediate success of arterial surgery.

Ankle↗

PubMedDate not supplied

[Results and mechanism of action of non-perforating deep sclerotomy in intraoperative monitoring of the hypotensive effect].

A total of 45 patients (45 eyes) were operated on by using the technique of non-perforating deep sclerotomy (NDST). A conclusion on the action mechanism, efficiency and indications for NDST was made on the basis of determining the retention degree and of the intraoperative monitoring of tonometry and tonography parameters. Perforations of various scopes were proven to have an impact on the surgical hypotensive effect; finally, intraoperative measures were suggested in case of NDST inefficiency.

Aged↗

PubMed1989

Intraoperative monitoring of Jones tube function.

If intraoperative visualization is impossible when placing a secondary Jones tube, the presence of tube drainage may confirm correct intranasal positioning. A simple suction method is presented to evaluate the intranasal position of the Jones tube in the anesthetized or uncooperative patient.

Catheterization↗

PubMed1989

[Intraoperative monitoring of spinal interventions with evoked potentials].

Monitoring the spinal cord can improve the safety margin during spinal surgery. This technique requires a stimulus source, transmitted through filters and amplifiers, and resulting in an enhanced signal that is recorded. Several techniques are now available, both non-invasive and invasive. We have carried out intraoperative monitoring during 178 spinal operations to correct deformities. Cortical somatosensory evoked potentials (CSEP) were obtained with Fz-Cz' recording sites, following bilateral posterior tibial nerve stimulation. In addition, unilateral median nerve stimulation was performed as a control. Six cases with an intraoperative alteration in waveform are described.

Adolescent↗

PubMed1999

Efficacy of intraoperative monitoring for pediatric patients with spinal cord pathology undergoing spinal deformity surgery.

STUDY DESIGN: A retrospective study of 38 pediatric patients with spinal cord pathology who underwent corrective spinal deformity surgery from January 1989 through June 1998. OBJECTIVES: To report reliability and specificity in obtaining intraoperative data in this population. These data were compared with monitoring results obtained in a group of pediatric patients with idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Reports in the literature suggest intraoperative monitoring for patients with spinal cord pathology may be of limited value. No optimal monitoring protocol has been suggested for this population. METHODS: The study group consisted of 38 pediatric patients with a diagnosis of spinal cord pathology who underwent corrective spinal deformity surgery from January 1989 through June 1998. All patients had lower extremity function. Somatosensory and neurogenic motor evoked potentials were used to monitor neurologic status during surgery. These data were compared with data obtained in 429 pediatric patients with idiopathic scoliosis. Study patients were divided into Group I, those who had had spinal cord surgery (n = 20), and Group II, those who had not (n = 18). RESULTS: Somatosensory evoked potentials were obtained in 93.2% and remained consistent with baselines in 87.2% of the study group patients. Neurogenic motor evoked potentials were obtained in 50.8% of the study subjects and remained consistent in 76.6% of those cases. The false-positive rate was 27.1% in the study group, compared with 1.4% in the group with idiopathic scoliosis. The study group had no true-positive or false-negative findings. Group I data differed from Group II data. CONCLUSIONS: Intraoperative monitoring should be used in patients with spinal cord pathology who undergo surgery for spinal deformity. Monitoring should not miss a neurologic deficit but demonstrates greater variability, resulting in more frequent use of an intraoperative wake-up test.

Adolescent↗

PubMed2001

Intraoperative monitoring of facial EMG responses during microvascular decompression for hemifacial spasm. Prognostic value for long-term outcome: a study in a 33-patient series.

Lateral spread responses (LSR), an electrophysiological characteristic of hemifacial spasm (HFS), can be recorded during surgery. This work aims at evaluating the prognostic value of the persistence or suppression of the LSR at the end of the microvascular decompression (MVD) procedure of the facial nerve. Thirty-three patients with HFS, which had been evolving for 5.5 years, underwent MVD with intraoperative EMG. Monitoring required the placement of a needle in the frontalis and mentalis muscles. Responses were recorded after stimulation of inferior or superior branches of the facial nerve to search for abnormal ephaptic LSR. Preoperative abnormal LSRs were present in all patients. In 23 patients, LSR disappeared with vascular decompression and was not present upon closure. Among those patients, 20 were considered clinically cured and three still presented with mild/moderate spasm at 3-month follow-up. At late follow-up, 22 patients were free of spasm. One patient had recurrence of spasm at month 10. On the contrary, 10 patients had persistent abnormal LSR upon closure. Among those, seven were cured at early follow-up (3 months on average), whereas spasm disappeared at late follow-up (12 to 36 months) in the other three patients. The prognostic value of LSR monitoring is questionable; a good clinical result may be obtained in patients who presented with persistent LSR at the end of MVD. Delayed cure strongly supports the hypothesis that HFS is not only due to the mechanical pulsations of the elongated artery against the root exit zone of the facial nerve, but also to demyelination of the nerve and/or hyperactivity of the facial motornucleus generated by the neurovascular compression.

Adult↗

PubMed2004

Hypotension-induced loss of intraoperative monitoring data during surgical correction of scheuermann kyphosis: a case report.

STUDY DESIGN: Presentation of a case report of Scheuermann kyphosis surgical correction. OBJECTIVE: To describe a scenario where both neurogenic mixed evoked potentials and somatosensory-evoked potentials were lost due solely to hypotension before any correction of a kyphotic spinal deformity was performed. SUMMARY OF BACKGROUND DATA: Multimodality intraoperative neurophysiologic monitoring of the spinal cord has become widely utilized during surgical correction of scoliotic and kyphotic deformities. Most spinal surgeries also benefit from a state of hypotension to minimize blood loss, but unchecked and persistent hypotension may lead to inadequate perfusion to the spinal cord, resulting in spinal cord dysfunction noted by diminution of neuromonitoring data. METHODS: An 18-year-old boy with a 95 degrees Scheuermann kyphosis underwent a posterior spinal fusion for correction of his deformity. Intraoperative neurophysiologic monitoring consisting of neurogenic mixed evoked potentials and somatosensory-evoked potentials were performed throughout surgery. RESULTS: After placement of segmental pedicle screw fixation points and multiple osteotomies, before any instrumented correction of the deformity, all lower extremity neuromonitoring data were acutely lost. The surgeon was immediately warned of the data loss, with the mean arterial pressure noted to be 50 mm Hg. The mean arterial pressure was raised with the use of epinephrine bolus and dopamine infusion. Subsequently, all lower extremity neuromonitoring data returned. A Stagnara wake-up test was performed, which the patient passed, and the surgical correction was performed with his pressure maintained on a dopamine infusion. He awakened without neurologic deficits and had an uneventful recovery. CONCLUSIONS: Although a state of mild hypotension may be beneficial to limit blood loss during spinal deformity corrective surgery, acute and/or prolonged hypotension may jeopardize spinal cord vascularity and should be avoided especially during surgical treatment of high-risk deformities such as kyphosis. Early warning by multimodality physiologic neuromonitoring appears to be a useful method to alert surgeons of the potentially devastating problem of hypotension-induced spinal cord dysfunction and allows immediate corrective actions.

Adolescent↗

PubMed1986

Use of a flexible epidural stimulating electrode for intraoperative monitoring of spinal somatosensory evoked potentials.

The use of an epidural stimulating spinal electrode has been adapted for recording spinal somatosensory evoked potentials (SSEP) during spinal surgery. This technique utilizes a flexible, 1 mm diameter electrode with four platinum contacts that is easily slipped into the epidural space both rostral and caudal to the exposed surgical field. The flexibility of the electrode assembly ensures against dural penetration. Incoming somatosensory spinal evoked potentials recorded using the lumbosacral electrode are compared with the SSEP recorded above the surgical site (rostral electrode). The spinal SEPs were generally triphasic (thoracic) or polyphasic (lumbosacral) with an amplitude of 5 microV. This system has been used for intraoperative monitoring during 33 major spinal operations. Waveform morphology, as well as the latencies and amplitudes of the component peaks of the spinal SEPs remained relatively constant compared with the cortical SEPs.

Electric Stimulation↗

PubMed2002

[Intraoperative monitoring of intact parathyroid hormone during surgery for primary hyperparathyroidism].

The aim of the present study was to evaluate a new immunometric assay for intraoperative parathyroid hormone monitoring. The test was applied in 70 patients who underwent surgery for primary hyperthyroidism (pHPT) between 6/1999 and 6/2001. Among these patients, 61 showed a solitary adenoma, eight a hyperplasia and one a double adenoma. Intraoperative iPTH samples were taken at the beginning of the operation and 5, 10 and 15 min after removal of the parathyroid gland. Criterion for a successful operation were a decrease of iPTH levels of more than 50 % within 5 min and of more than 60 % within 15 min after parathyroidectomy. Following the removal of a solitary adenoma, iPTH levels decreased by 63 % (+/- 13 %) after 5 min and by 76 % (+/- 10 %) after 15 min respectively. In case of hyperplasia, a significant decrease of iPTH levels was not observed until a subtotal parathyroidectomy had been carried out. In the present study there were 2 false negative and one false positive results corresponding with a sensitivity of 97 % and a specificity of 89 % for prediction of a solitary adenoma. In our opinion, intraoperative iPTH monitoring using this new assay allows the safe distinction between adenoma and multiglandular disease. It represents a valuable adjunct to surgical skill as it permits minimally invasive operations for solitary adenomas, and in case of recurrent surgery helps to detect the region of interest by selective venous sampling for parathyroid hormone.

Adenoma↗

PubMed2002

Intraoperative monitoring of brain tissue oxygen and carbon dioxide pressure in peritumoural oedema by stereotactic placement of multiparameter microsensors.

Ischaemia may play an important role in peritumoural brain oedema and swelling, but little data exist so far on brain tissue oxygenation adjacent to a tumour mass. We have monitored brain tissue oxygen tension (ptiO2) and brain tissue CO2 tension (ptiCO2) in 19 patients undergoing craniotomy for resection of a brain tumour using a multiparameter sensor placed in the brain parenchyma. Accurate placement of this probe in the peritumoural area was accomplished with the aid of a 3-D neuronavigation system. Due to various problems we obtained useful data in only 13/19 patients. The presence of brain swelling was associated with a significant rise in ptiO2 upon opening of the dura from 7.1 +/- 7.8 to 23.6 +/- 14.7 mm Hg. The average ptiO2 before tumour resection was 18.1 +/- 10.8 mm Hg. A significant improvement in ptiO2 occurred after tumour resection to an average ptiO2 of 29.7 +/- 15.2 mm Hg. From these preliminary data, we conclude that ptiO2 is depressed in the peritumoural area, and improves following tumour resection. Stereotactic placement of sensors for intraoperative ptiO2 monitoring is feasible and may enhance data quality. Nevertheless, the high incidence of failures with this type of sensor remains a matter of concern.

Adult↗

PubMed2001

Gentle dorsal root retraction and dissection can cause areflexia: implications for intraoperative monitoring during "selective" partial dorsal rhizotomy.

During partial dorsal rhizotomy (PDR), intraoperative dorsal rootlet stimulation often evokes nonreflex, rather than reflex, motor responses that are due to costimulation of adjacent ventral roots. Intraoperative areflexia typically predicts that motor responses evoked by dorsal rootlet stimulation are nonreflexive. The cause of areflexia during PDR is in part due to anesthesia, but other mechanisms are likely to play a role as well. In this study of three consecutive patients undergoing lumbosacral neurosurgery, soleus H-reflexes evoked by tibial nerve stimulation at the popliteal fossa were found to suddenly decline in amplitude following retraction and gentle dissection of the S-1 dorsal root. In one areflexic patient, dorsal rootlet stimulation proximal to the main site of dissection evoked soleus H-reflexes, although they could not be evoked by tibial nerve stimulation. We conclude that the gentle retraction and dissection of dorsal rootlets that occurs during PDR can induce conduction block of reflex afferents. High-intensity dorsal rootlet stimulation distal to the site of conduction block may then evoke not reflex responses, but rather nonreflex motor responses, due to the costimulation of adjacent ventral roots.

Cerebral Palsy↗

PubMed1996

The critical importance of stimulus intensity in intraoperative monitoring for partial dorsal rhizotomy.

During partial lumbosacral dorsal rhizotomy (PDR), intraoperative dorsal rootlet stimulation (drs) evokes motor responses, presumed to be reflexes, which are used to select rootlets for section. However, dr stimuli may also costimulate ventral root (vr) and evoke an M rather than a reflex response, the two being distinguishable only by comparison of response latencies after drs at two separate sites. In 15 consecutive spastic cerebral palsy patients undergoing PDR, we asked whether reflex and M responses were distinguishable on the basis of stimulus intensity (SI). For soleus H reflexes evoked by percutaneous tibial nerve stimulation, the SI for reflex afferents was usually subthreshold for exciting motor fibers. Similarly, for nerve roots, reflexes were evoked by drs at SIs generally less than that for M responses evoked by vr stimulation (vrs). In contrast, M responses evoked by drs required SIs that were on average 20 times greater. Finally, costimulation of contralateral vr after ipsilateral vrs occurred at SIs shown to evoke M responses after drs. We conclude that: (1) reflex and M responses evoked by drs are distinguishable on the basis of the required SI; and (2) drs employing SIs greater than required for vrs evokes M rather than reflex responses due to costimulation of ipsilateral and contralateral vr.

Cerebral Palsy↗

PubMed1991

[Intraoperative monitoring with evoked potentials in spinal interventions].

This review article delineates the physiology and methodological principles of somatosensory (SEP) and motor evoked potentials (MEP), as well as our own results in 40 patients monitored during spinal surgery. In 29 patients an intraoperative SEP and in 15 patients a MEP monitoring was performed. Both modalities were applied in 4 patients. 19 patients had an intramedullary tumor, 15 patients had an intradural extramedullary tumor, 4 patients had an extradural mass lesion, and 2 patients had a spinal arteriovenous malformation. Technical problems with SEP monitoring occurred in 3 of 29 cases, problems with MEP monitoring occurred in 4 of 15 cases. Whereas anesthesia showed only little influence on SEP, an appropriate anesthesiological management was of major importance for MEP monitoring. Other factors, e.g. body temperature and blood pressure, also affected the evoked potentials. In all 35 patients in whom intraoperative SEP and/or MEP monitoring was successfully performed, evoked potentials showed a clear correlation with the initial postoperative neurological findings i.e. there were only cases of correct positive or correct negative monitoring. Transient evoked potential changes could always be attributed to surgical maneuvers. Our results show that intraoperative spinal cord monitoring with both SEP and MEP can supply helpful information on neural integrity. The choice of the evoked potential modality to be used and the choice of the sites of stimulation and recording depends on individual pathoanatomical findings and on the operative procedure required. Intraoperative evoked potential monitoring is indispensable during high risk spinal surgery such as surgery for intramedullary tumor or for mass lesions above C5.

Afferent Pathways↗

PubMed2005

Intraoperative monitoring of blood flow insufficiency during surgery of middle cerebral artery aneurysms.

OBJECT: The usefulness of motor evoked potential (MEP) monitoring to detect blood flow insufficiency (BFI) in the cortical branches of the middle cerebral artery (MCA) and lenticulostriate arteries (LSAs) during MCA aneurysm surgery was investigated based on the correlation between MEP and somatosensory evoked potential (SEP) monitoring. METHODS: Fifty-three patients with MCA aneurysms underwent surgery accompanied by intraoperative MEP and SEP monitoring. There was no postoperative motor paresis in 43 patients in whom MEP and SEP results remained unchanged. In the other 10 patients, nine manifested transient MEP changes; in five of these, SEP changes did not occur. The transient MEP changes were thought to be attributable to BFI of the MCA cortical branches in two patients, the LSA in three, and either the MCA branches or the LSA in four patients. Of these nine patients, six did not present with postoperative motor paresis; transient motor paresis was recognized in the other three. In the 10th patient, MEP waves disappeared and did not recover. This patient's SEPs remained at 70% of the control level, and he developed severe hemiparesis. A postoperative computerized tomography scan revealed a new low-density area in the corona radiata and putamen. CONCLUSIONS: Blood flow insufficiency in both the LSA and MCA cortical branches that perfuse the corticospinal tract can be detected by intraoperative MEP monitoring. Somatosensory evoked potential monitoring is not reliable enough to detect BFI in the MCA branches and the LSAs.

Aged↗