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Results for “Monitoring, Intraoperative”

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At least 559 records · Page 31Linked to original sources

PubMed1992

Hearing prognosis and intraoperative guidance of brainstem auditory evoked potential in microvascular decompression.

Intraoperative monitoring of brainstem auditory evoked potential (BAEP) was done in 34 patients submitted to microvascular decompression (MVD). Seventeen of these patients had trigeminal neuralgia, and 17 had hemifacial spasm. Transitory postoperative hearing loss was observed in 6 (18%) of the patients, and permanent hearing loss was observed in 2 (6%) of the patients. Wave I-V interpeak latency (IPL) was calculated during each step of the MVD procedure in order to identify the dangerous steps of the surgery. Wave I-V IPL abnormalities occurred more frequently during cerebellar retraction. Of the 6 patients who had total loss of BAEP lasting throughout the surgery, 1 (17%) had definitive deafness. Ten of the 34 patients had an absence or partial diminution of BAEP without total normalization before the end of surgery. Among these 10 patients, 2 had transitory hearing loss and 1 had permanent hearing loss.

Adult↗

PubMed2005

Optic nerve evoked potentials elicited by electrical stimulation.

This study investigated whether the optic nerve evoked potential (ONEP) elicited by electrical stimulation of the optic nerve can serve as a reliable intraoperative indicator of visual function. In the experimental study, two silver-ball stimulating electrodes were placed on the dog optic nerve adjacent to the apex of the orbit and one recording electrode was placed on the optic nerve near the chiasm. The nerve was stimulated with 0.1 to 10 mA rectangular pulses. Stable and reproducible ONEPs were obtained. The ONEPs were not influenced by electromyographic potentials and were recorded more clearly on the optic nerve than on the surrounding tissue. Stepwise incremental transection of the thickness of the nerve resulted in incremental amplitude reduction proportional to the transected area. No response was recorded after complete sectioning of the nerve. In the clinical study, recordings were obtained from 15 patients after craniotomy to treat parasellar tumors or cerebral aneurysms. Reproducible ONEPs were recorded intraoperatively from the electrode placed on the optic nerve near the chiasm in 14 of 15 patients. In the remaining patient, the ONEP, recorded only after tumor removal because the optic nerve was stretched and extremely thin, was remarkably small and the patient developed unilateral blindness postoperatively. These experimental and clinical results suggest the possibility of intraoperative monitoring of visual function in patients undergoing craniotomy for the treatment of lesions near the optic nerve.

Adult↗

PubMed2003

Improvement in brainstem auditory evoked potentials after suboccipital decompression in patients with chiari I malformations.

OBJECT: The optimal treatment for patients with symptoms related to Chiari I malformation remains controversial. Although a suboccipital decompression with duraplasty is most commonly performed, there may be a subset of patients who improve in response to bone decompression alone. In an initial attempt to identify such patients, we performed a continuous study of intraoperative brainstem auditory evoked potentials (BAEPs) in patients undergoing a standard decompression with duraplasty and compared conduction times at three different time points: 1) baseline while the patient is supine (before positioning); 2) immediately after opening of the bone and release of the atlantooccipital membrane (that is, the dural band); and 3) after opening of the dura mater. METHODS: Eleven children and young adults (mean age 9.8 years) with symptoms related to Chiari I malformation underwent suboccipital decompression and duraplasty with intraoperative monitoring of BAEPs and somatosensory evoked potentials (SSEPs). Six patients (55%) had associated syringomyelia. At baseline, the I to V interpeak latency (IPL) for both sides (total 21 BAEPs) was 4.19 +/- 0.22 msec (mean +/- standard deviation). After complete bone decompression and before the dura mater was opened, the I to V IPL decreased to 4.03 +/- 0.25 msec (p = 0.0005). When the dura was opened, however, no further decrease in the I to V IPL was detected (4.03 +/- 0.25 msec; p = 0.6). The SSEPs remained stable throughout the procedure. CONCLUSIONS: In children and young adults undergoing suboccipital decompression with duraplasty for Chiari I malformation, the vast majority of improvement in conduction through the brainstem occurs after bone decompressionand division of the atlantooccipital membrane, rather than after opening of the dura. Additional studies are needed to establish whether the improvement seen with BAEP monitoring during bone decompression will predict long-term clinical improvement in these patients.

Adolescent↗

PubMed2006

Intraoperative corticomuscular motor evoked potentials for evaluation of motor function: a comparison with corticospinal D and I waves.

OBJECT: The goal of this study was to compare motor evoked potentials recorded from muscles (muscle MEPs or corticomuscular MEPs) with corticospinal MEPs recorded from the cervical epidural space (spinal MEPs or corticospinal MEPs) to assess their efficacy in the intraoperative monitoring of motor function. METHODS: Muscle and spinal MEPs were simultaneously recorded during surgery in 80 patients harboring brain tumors. Each case was assigned to one of four groups according to final changes in the MEPs: (1) Group A, in which there was an increased amplitude in the muscle MEP with an increased 13 wave amplitude (12 cases); (2) Group B, in which there was no significant change in the MEP (43 cases); (3) Group C, in which there was a decreased muscle MEP amplitude (< 35% of the control) with a decreased I wave amplitude but an unchanged D wave (15 cases); or (4) Group D, in which there was an absent muscle MEP with a decreased D wave amplitude (10 cases). In patients in Group A, the increase in the amplitude of the muscle MEP (range of increase 128-280%, mean increase 188.75 +/- 48.79%) was well correlated with the increase in the 13 wave in corticospinal MEPs. Most of these patterns were observed in patients harboring meningiomas (10 [83.3%] of 12 cases). Patients in Group B displayed no changes in muscle and corticospinal MEPs and no signs of postoperative neurological deterioration. Patients in Group C showed a substantial decrease in the amplitude of the muscle MEP (range of decrease 5.3-34.8% based on the control waveform, mean change 21.81 +/- 10.93%) without deterioration in the corticospinal D wave, and exhibited severe immediate postoperative motor dysfunction. This indicates dysfunction of the cortical gray matter, including the motor cortices, which are supposed to generate I waves. Patients in Group D exhibited decreases in the corticospinal D wave (range of decrease 21.5-55%, mean decrease 39.75 +/- 11.45%) and an immediate cessation of the muscle MEP as well as severe permanent motor paresis. CONCLUSIONS: These results indicate that, during surgery, monitoring of corticomuscular MEPs (which are related to I waves) is a much more sensitive method for the detection of immediate motor cortical damage than monitoring of corticospinal MEPs (D wave).

Adolescent↗

PubMed1995

Primary bone tumors of the spine: a survey of the evaluation and treatment at the Istituto Ortopedico Rizzoli.

The experience at Istituto Rizzoli with 366 primary bone tumors of the spine focuses on the criteria for planning and treatment. An accurate preoperative evaluation by standard radiograph, computerized tomography scan, and magnetic resonance imaging allow the classification of benign lesions as latent (not requiring treatment), active (curettage), or aggressive (curettage plus adjuvants or marginal resection). The malignant lesions are classified as intracompartmental or extracompartmental (both low and high grade). Wide resection is attempted, but seldom is feasible. An angiographic study of the spinal cord is compulsory for lesions located in the thoracolumbar region. The value of embolization is enhanced, primarily in highly vascular lesions. An accurate preoperative study of the vital parameters of the patient, together with a continuous intraoperative monitoring, is mandatory.

Adult↗

PubMed1999

[Anesthetic problems during long interventions in mouth, jaw and facial surgery].

Long-lasting and extended maxillofacial surgery with operating times of more than ten hours are now routinely performed with an acceptable risk for the patient. Careful preoperative evaluation of the patient and interdisciplinary planning are essential for successful surgery. The close proximity of the surgical field and the airways as well as a high incidence of difficult intubation in these patients require special attention from the anaesthesiologist. Other perioperative focuses of anaesthesiological concern in long-lasting maxillofacial surgery are positioning of the patient, intra- and postoperative airway management, intraoperative monitoring, thermoregulation, fluid replacement and transfusion therapy.

Anesthesia, General↗

PubMed2000

[Cerebral ischemia during carotid clamping: diagnosis and prevention].

A serious complication in carotid endarterectomy (CEA) is the occurrence or aggravation of neurological deficits caused by insufficient collateral cerebral blood flow during cross-clamping. At the moment, patients with failure of collateral circulation at this point cannot be identified preoperatively. Thus, intraoperative monitoring and methods to prevent clamping-related cerebral ischemia are required. To put this strategy into clinical practice there are several methods of monitoring cerebral function (e.g. surgery performed in awake patients, electroencephalography, somatosensory evoked potentials), changes of hemodynamic (e.g. carotid stump pressure, transcranial Doppler ultrasonography) or metabolic parameters (e.g. jugular bulb oximetry or transcranial oximetry). One technique that meets nearly all requirements of an ideal monitoring under general anesthesia is the use of somatosensory evoked potentials (SEPs). Registration of SEPs is simple to perform and indicates with a high sensitivity and specificity critical cerebral hypoperfusion during cross-clamping. Thus, SEPs monitoring indicates the necessity of shunt placement. As a result, the use of an indwelling shunt as the most effective method to prevent clamping ischemia can be limited to selected cases, avoiding the risks of shunting in patients with sufficient collateral flow. In addition, correct shunt function is immediately indicated by recovering potentials. Whether a combination of SEPs with transcranial Doppler measurements will be successful to provide additional information about cerebral embolisation should be determined.

Brain Ischemia↗

PubMed2001

[Effect of bolus propofol administration on muscle evoked potential (MsEP) during spine surgery].

Intraoperative monitoring of descending pathways by means of muscle evoked potential (MsEP) is a reliable method to monitor spinal cord motor function, but MsEP is readily affected by anesthetics. We monitored MsEP evoked by repetitive transcranial electrical stimulation of the motor cortex in 30 patients receiving spine surgery. Total intravenous anesthesia was maintained with propofol and fentanyl without any muscle relaxant. Onset latencies and peak to peak amplitudes of MsEP were evaluated before and after the bolus propofol administration. The concentrations of propofol in blood and the effect-site during MsEP monitoring were predicted by computer simulation software. The amplitude of MsEP decreased slightly by bolus propofol administration, but the latencies showed no significant change with propofol under the same condition. We consider that total intravenous anesthesia with propofol and fentanyl without muscle relaxants is compatible with the recording of MsEP evoked by high frequency repetitive electrical transcranial stimulations. When MsEP is monitored during spine surgery, anesthetic condition should be controlled carefully in order to maintain a stable blood concentration of propofol and thus to assure the reliability of MsEP measurements.

Adolescent↗

PubMed2003

Evoked potential changes in ischaemic myelopathy.

Somatosensory evoked potentials are employed in the intraoperative monitoring but there is paucity of information about the motor evoked potentials (MEP) in spinal cord ischaemia. Two patients aged 9 and 4 years developed paraplegia following surgery for coarctation of aorta. The aortic cross clamping time in these patients was 100 min and 30 min. respectively. The patient with longer clamping time had flaccid paraplegia and lower limb MEPs were not recordable; whereas the patient with shorter clamping time had spastic paraparesis and prolonged CMCT to right lower limb. The latter patient improved significantly. Tibial SEPs were normal in both the patients. Our results suggest that MEP may have a greater role than SEP in documenting and prognosticating ischaemic myelopathy.

Aortic Coarctation↗

PubMed1992

Dissociation of somatosensory and motor evoked potentials in a patient with an intramedullary spinal tumor.

We describe a patient with an intramedullary spinal tumor who demonstrated postoperative improvement of motor and sensory function despite the lack of somatosensory evoked potentials (SSEPs) before and after intraoperative monitoring. The motor system was evaluated by direct spinal cord stimulation across the tumor bed. The resultant evoked compound muscle action potentials and compound nerve activities were normal. Although there is sufficient clinical evidence that SSEPs are sensitive to posterior and posterolateral ischemic insults of the spinal cord, the technique should be employed with an awareness of its limitations in monitoring the descending tracts which have a different blood supply and occupy more anterior locations in the spinal cord.

Arm↗

PubMed1992

Neurophysiological evaluation of disorders and procedures affecting the spinal cord and the cauda equina.

Neurophysiological tests that asses afferent or efferent pathways of the spinal cord and of nerve roots are used for clinical diagnosis, intraoperative monitoring, and judgement of prognosis. Most tests can readily be performed in awake subjects, whereas many difficulties arise in anesthetized patients in whom neurophysiological testing is the only way of monitoring functional integrity of neural tissue. The research, therefore, that has been carried out in this field during the past year is of special interest.

Cauda Equina↗

PubMed1992

[Rebound hyperglycemia and peroperative normalization of insulinemia. Complete excision of insulinoma?].

Clinical usefulness of the hyperglycemic rebound and the normalization of plasma insulin level as intraoperative markers of complete removal of insulinoma was assessed. Surgical removal was curative (no clinical or biological recurrence) in six patients harboring a single adenoma (mean follow-up = 32.2 months). In these patients plasma glucose increased an average of 32 mg/dl 30 minutes after resection, 68 mg/dl after 60 minutes, and 91 mg/dl after 90 minutes. Sensitivity of hyperglycemic rebound (defined as a plasma glucose increment of at least 30 mg/dl after tumor removal) as a marker of complete resection of the insulinoma was 40% at 30 min and 83% at 60 minutes after resection. Preresectional values of plasma immunoreactive insulin were elevated in 3 out of 4 patients with adenoma. All postresectional values were within normal ranges. Two patients operated on because of malignant insulinoma, underwent partial tumor resection; hyperglycemic rebound was also present, and high preresectional insulin values became normal 30 minutes after partial tumor removal. We conclude that information provided by intraoperative monitoring of both plasma glucose and insulin cannot be used as the only markers of complete resection of all insulinomas. Only long term clinical and biological follow-up can guarantee the complete resection of an insulinoma.

Blood Glucose↗

PubMedDate not supplied

[Maternal deaths and anesthetics in the Lomé (Togo) University Hospital].

AIM: To assess the results of anesthesia practices in a department particularly inadequately staffed with physicians specializing in anesthesiology. SETTING AND METHODS: This six-month prospective study (from January through June 2002) took place in the anesthesiology/intensive care unit of the obstetrics and gynecology department of Lomé University Hospital Center. A case report file was completed for each patient, and all anesthetics administered in the obstetrical department (labor and delivery room) were recorded and considered. We examined the perinatal deaths among women who underwent surgery. RESULTS: Anesthetics were administered to 318 women during cesarean delivery (306) and uterine scar repair (12). Nearly all patients (98%) were classified in categories 1 or 2 of the ASA physical status classification system (healthy or mild systemic disease). General anesthesia was induced in 95.9% of the women and spinal bloc used for 4.1%. Thiopental was used most often, and certain drugs, including succinylcholine and ephedrine, were not available as needed. Intraoperative monitoring was essentially nonexistent. Emergency situations accounted for 89.6% of these surgical procedures. Of the 16 cases requiring transfusions, an inadequate supply of blood products or the patient's inability to obtain blood was reported in 14 of the cases. Twelve deaths occurred, for a mortality rate among surgical patients of 3.8%. The principal causes of death were respiratory complications of anesthesia and of pregnancy-related toxemia and the unavailability of hypertonic solutions and blood products. CONCLUSION: The results of this survey show that anesthetics play a role in maternal mortality in Togo. Good practice guidelines adapted to this setting must therefore be developed.

Adolescent↗

PubMed2004

Perioperative management of the patient undergoing vascular surgery.

Providing optimal perioperative care to the patient undergoing vascular surgery is a continuum; it starts with an accurate preoperative identification and management of the associated comorbidities, evolves into an adapted selection of the level of intraoperative monitoring and the anesthetic technique, and implies an extension of the vigilant care into the postoperative period. The perioperative consultants, the anesthesiologists, and the surgeons should combine their efforts to accomplish this challenging task. Also, they should continuously upgrade their skills to cope with the development of new techniques, such as endovascular repairs, that may minimize postoperative morbidity.

Anesthesia↗

PubMed2005

[Surgical remodeling of the left ventricle in ischemic cardiomyopathy].

The paper covers early and long-term results of left ventricle geometric reconstruction and myocardial revascularization in 44 patients with ischemic cardiomyopathy. The authors have established clinical and hemodynamic criteria of ischemic cardiomyopathy, indications for surgical treatment and a surgical technique. The article presents a new approach to correction of mitral insufficiency in the given category of patients. According to the results of the study, the necessary conditions for a surgical intervention to be successful are: intraoperative monitoring of central hemodynamics using Swan-Ganz catheter, evaluation of myocardial contractile function by means of transoesophageal echocardiography and wide use of preoperative intraaortic balloon pumping. Geometric reconstruction results in normalization of left ventricle shape and its end-systolic and end-diastolic volumes, marked increase of ejection fraction and improvement of central hemodynamics. The stability of the long-term results has been confirmed in a 4-year follow-up.

Cardiac Surgical Procedures↗

PubMed2006

[Motor cortex stimulation for post-stroke pain using neuronavigation and evoked potentials: report of 3 cases].

Although motor cortex stimulation (MCS) has been accepted as an effective therapeutic option for central pain, the efficacy of MCS widely varies among previous reports. In this report, we describe our recent trial for successful MCS in 3 patients with central pain due to cerebral stroke. Medical treatments were transiently effective, but gradually became ineffective in all of the cases. During surgery, the appropriate cortical target was determined by using neuronavigation, somatosensory evoked potential (SEP), and motor evoked potential (MEP). A flat, four-plate electrode was positioned on the dura mater parallel to the motor cortex. After surgery, pain almost resolved in 2 of 3 patients and markedly improved in another. The pain relief depended on their motor function. These findings strongly suggest that both patient selection and intraoperative monitoring for targeting the motor cortex are quite important for successful MCS, although further studies were essential.

Aged↗

PubMed1990

[Intravesical echography. II. Staging].

We evaluated 137 patients with bladder cancer submitted to surgery in order to determine the usefulness of intravesical ultrasonography (IVU) in tumor staging. The characteristic scan images were defined for each tumor stage. The application of the ultrasound patterns yielded an accuracy rate of 91% for tumors Ta"1 and 71% for T4. Based on the results of this study, IVU does not appear to be useful as an intraoperative monitoring technique.

Adult↗

PubMed1995

Anesthesia for scoliosis: dwarfism and congenitally absent odontoid process.

Scoliosis surgery presents the anesthetist with specific clinical challenges. Since scoliosis is the most common problem for which patients of congenitally short stature present to the operating room, the preoperative evaluation of dwarfs is discussed here in the context of a patient with spondyloepiphyseal dysplasia congenita. In the case described, many of the deformities associated with dwarfism were present. The significance of these to the preoperative, intraoperative, and postoperative care is discussed. Consideration is given to cervical spine abnormalities, congenital absence of the odontoid process, pulmonary function abnormalities, and mucopolysaccharidosis (a syndrome which may compromise airway management). The intraoperative monitoring of somatosensory evoked potentials and their significance are also discussed.

Adolescent↗