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At least 577 records · Page 32Linked to original sources

PubMed1995

[Short-latency, brainstem, trigeminal evoked-potentials].

Short-latency, evoked-potentials were recorded from over the scalp in response to electrical stimulation of the upper lip, using the Microshev 4000 equipment (Microshev Co., Efrat). Normative data were obtained from 35 normal volunteers. The brain-stem, trigeminal evoked-potentials (BTEP) consisted of 4 distinct, well-reproduced waves evoked in less than 10 msec. The waves, named after their respective latencies, are thought to be generated in the preganglionic trigeminal nerve (T1), the postganglionic nerve entry zone (T2), in the trigeminal nucleus (T3) and the upper brainstem (T5). BTEP was recorded in nearly 200 patients suffering from various lesions in the peripheral trigeminal parts, tumors affecting the brainstem (before, during and after surgery) and in varying degrees of post-traumatic coma. BTEP proved to be a reliable tool for evaluating the brainstem trigeminal system; changes in its pattern reliably reflected altered activity of that system. It can be used for diagnosis as well as for intraoperative monitoring of brainstem function.

Brain Diseases↗

PubMed1994

[Abnormal evoked EMG and blink reflex responses in patients with hemifacial spasm (HFS)].

Abnormal evoked EMG and blink reflex responses have been observed on the affected side in patients with HFS. These characteristic responses were used as methods of preoperative differential diagnosis, and the disappearance of these abnormal responses during intraoperative monitoring was assessed as confirmation of nerve decompression. The subjects were 30 patients with a diagnosis of HFS. Three responses were evaluated: 1) the orbicularis oris muscle (OR) response to stimulation of the orbicularis oculi muscle branch (OB), OB-->OR; 2) the orbicularis oculi muscle (OC) response to stimulation of the marginal mandibular branch (MB), MB-->OC; and 3) the (OR) response to stimulation of the supraorbital nerve (SO), SO-->OR. The facial nerve in the root exit zone was compressed by a vessel in all 21 patients diagnosed as typical HFS who had abnormal responses, and OB-->OR was always detected. The MB-->OC and SO-->OR detection rates were low (50% and 25%, respectively) when the interval since the onset of HFS was less than 3 years, but increased to 78% and 67%, respectively, when it was 3 to 5 years, and all three abnormal responses were always detected when the interval was more than 5 years. In 17 of the patients these responses began to change and eventually disappeared before decompression of the facial nerve, and in 2 patients they persisted even after decompression. Abnormal responses disappeared at the time of decompression in only 2 patients, and their HFS was completely cured postoperatively. These findings confirmed that disappearance of abnormal responses is not a very useful guide for facial nerve decompression.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1993

[Anesthesia in urologic laparoscopic surgery].

Although minimally invasive, urological laparoscopic surgery is still a major surgery and has special characteristics which should not be ignored. Our protocol includes: premedication with diazepam and atropine, preinduction with fentanyl, induction with propofol, followed by atracurium or succinylcholine for tracheal intubation. Anesthesia is sustained with continuous pump infusion of propofol at gradually lower doses and is discontinued on removing the abdominal trocars. Muscle relaxation throughout the operation is maintained with atracurium in continuous infusion and is discontinued at the same time as propofol. Intraoperative analgesia is achieved with bolus administration of fentanyl. We routinely use vesical and nasogastric catheters; the latter is removed at the end of the operation. Similarly, compressive bandaging is done for the lower limbs in all patients. Intraoperative monitoring includes ECG, heart rate, arterial blood pressure (noninvasive method), end expiratory CO2, O2 saturation, minute/volume, tidal volume and respiratory rate, airway pressures, temperature and diuresis. Pulmonary ventilation is by IPPV with a mixture of oxygen and air, maintaining FiO2 at 0.4. Nitrous oxide is not utilized, therefore the airways were only used for lung ventilation and not for the administration of inhalatory anesthetic agents. The higher increments of end expiratory CO2 of up to 48 mm Hg were observed at the end of the procedure following peritoneal desufflation. In summary, the technique of choice is total i.v. anesthesia with propofol and monitoring as complete as possible (noninvasive). Furthermore, capnographic and capnometric control of end expiratory CO2 is warranted.

Adolescent↗

PubMed1993

Brain damage after profoundly hypothermic circulatory arrest: correlations between neurophysiologic and neuropathologic findings. An experimental study in vertebrates.

Five groups of neonatal pigs were subjected to cardiopulmonary bypass with circulatory arrest periods that varied from 70 to 120 minutes for the investigation of brain changes in induced deep-core hypothermia (15 degrees C) with circulatory arrest. The parameters that were analyzed were (1) microscopy of the brain in animals at 6 hours after bypass procedures and (2) intraoperative monitoring of somatosensory evoked potentials. Microscopic cellular damage appeared in all animals with a circulatory arrest period of more than 70 minutes. These changes involved mainly Purkinje's cells of the cerebellum, and they affected particularly the inferior half of the cerebellum. The prolongation of latency in the cortical responses, which reflects a slowing of the neural transmission with hypothermia, occurred in all animals. The late evoked potentials remained absent in all piglets with circulatory arrest periods of 90, 105, and 120 minutes, but they were fully recovered in all piglets of the control group and those with 70-minute arrest times. We concluded that the cerebellar region is the most sensitive site in which ischemic lesions attain their maximal severity and extent, and the maximum time of circulatory arrest without histopathologic and neurophysiologic sequelae should not exceed 70 minutes.

Animals↗

PubMed1993

Laparoscopy in high-risk cardiac patients.

Fifteen patients with severe cardiac disease (American Society of Anesthesiologists III or IV) underwent laparoscopy using radial artery and pulmonary artery catheters to determine intraoperative hemodynamic changes. Cardiac output (CO), mean arterial blood pressure (MAP), central venous pressure, heart rate, systemic vascular resistance (SVR) and mixed venous oxygen saturation (SVO2) were recorded before anesthetic induction, after induction, but before peritoneal insufflation, after insufflation and after release of pneumoperitoneum. Peritoneal insufflation led to significant elevations in MAP and SVR and reduction in CO. For seven patients, a decrease in SVO2 after peritoneal insufflation was predictive of significant worsening of hemodynamic parameters, suggesting inadequate cardiac reserve. In all patients, hemodynamic parameters returned toward baseline once pneumoperitoneum was released. There were no perioperative cardiac complications. While it is evident that laparoscopy presents serious hemodynamic stress, it can be performed safely in high-risk patients, using aggressive intraoperative monitoring.

Adult↗

PubMedDate not supplied

Use of a Doppler pulmonary artery catheter for continuous measurement of right ventricular pump function and contractility during single lung transplantation.

Despite numerous technologic advances in intraoperative monitoring, the only methods routinely available for assessment of right ventricular function in lung transplant recipients are continuous measurement of right heart pressures and intermittent thermodilution determination of cardiac output and ejection fraction. Additional data may now be obtained with transesophageal echocardiography, although this technology is expensive and not widely available and requires diverting attention from a potentially unstable patient for data acquisition and analysis. Recently, a Doppler pulmonary artery catheter was introduced that measures beat-to-beat pulmonary artery blood flow-velocity, cross sectional area, and volume flow. Because of data indicating that acceleration of blood in the pulmonary artery (measured as the first derivative of either the velocity or flow waveform) is a sensitive indicator of right ventricular contractility, we have used waveforms obtained with the catheter for assessment of right ventricular pump function (stroke volume and peak pulmonary artery flow rate) and contractility in heart surgery patients. We report here our experience with this method in two patients undergoing left single lung transplantation.

Adult↗

PubMed1995

Advances in surgery for brain tumors.

Significant advances in the management of neurosurgical disorders during the past decade have enhanced the safety of intracranial surgery, resulting in the ability of most patients with brain tumors to undergo successful resection now. Among these advances are stereotactic surgical procedures and intraoperative monitoring devices; future directions in neurosurgery include the application of advances in robotics and virtual reality. The surgical considerations and complications that accompany these advances are factors that the neurosurgeon must evaluate along with the choice of management.

Adult↗

PubMed1996

Abnormal electrocochleography after excision of acoustic neuroma.

Pre-, per- and post-operative ECoG findings obtained from a 43-year-old woman with an acoustic neuroma were studied. Although CAP presented a normal waveform in response to click during the whole process of the operation, it was transformed into an abnormally broadened negative waveform in shape with a mild hearing exacerbation, and has remained unchanged up to the present. This broad response was considered to be a receptor potential, because it showed no adaptational amplitude reduction. Additionally, postoperative ECoG to tone burst stimuli demonstrated an increase in DC potential following the stimulus envelope. Consequently, the broad negative response to click was considered to be mainly composed of an enlarged negative SP. The generation mechanism underlying the phenomenon of an abnormally increased negative SP found after the excision of an acoustic neuroma is discussed, with reference to several items in the literature. Similar responses in the postoperative ECoG of patients with acoustic neuromas obtained by us in the past were given as additional examples. CAP as an indicator for intraoperative monitoring can hardly predict postoperative auditory function. It is to be hoped that a more reliable auditory monitoring method during the operation will be established.

Adult↗

PubMed1996

[Does multi-vessel disease of brain supplying arteries modify the procedure in carotid operations?].

In a prospective evaluation 159 patients with carotid artery stenosis showed a multiple artery disease in 78 to 99% depending on the grade of cerebral artery insufficiency. Contralateral occlusion process could be detected in 15.7%, internal and common carotid artery occlusion in 16 patients (10%). 1595 patients picked out of the literature have been analyzed in respect of the natural history which showed a risk to develop a stroke in 4.5%/year. In further 1286 operated patients of other reports the morbidity and mortality rate ranged 4.5% and the risk of further neurologic events after operation was 2.4%/year. The use of an intraluminal shunt after thrombendarterectomy proved to be a good procedure to lower the morbidity and mortality rate without any intraoperative monitoring.

Blood Vessel Prosthesis↗

PubMed1997

[Minimally invasive technique for mitral valve repair--the importance of intraoperative transesophageal echocardiography].

A 65-year-old male with mitral regurgitation was scheduled for the mitral valve repair by means of minimally invasive technique. The technique, which requires a 10-cm right parasternal incision, offers minimal discomfort, less postoperative pain, quick functional recovery and excellent cosmetic healing. However, the intraoperative monitoring by the transesophageal echocardiography was required to evaluate the mitral valve function and to confirm the complete removal of air from the apex of the left ventricle and right upper pulmonary vein due to the small operative field. In addition, the monitoring of the short-axis view of the left ventricle makes it possible to evaluate and to confirm the preload and the left ventricular contractility. We considered that the transesophageal echocardiography is essential and useful for the minimally invasive mitral valve repair.

Aged↗

PubMed1997

[Evaluation of cerebral perfusion during aortic clamping and cross-clamping in patients undergoing resection for abdominal aortic aneurysm. A study with transcranial doppler].

OBJECTIVE: To evaluate the cerebral blood flow parameters assessed by transcranial Doppler during aortic cross-clamping and unclamping in patients undergoing abdominal aortic aneurysmectomy. METHODS: Invasive intraoperative monitoring of mean arterial pressure (MAP) and PaCO2, and right middle cerebral artery (RMCA) monitoring of blood flow parameters (mean velocity "Vm" and pulsatility index "PI") by transcranial Doppler were performed as well as evaluation of the four parameters during these subsequent periods: pre-cross-clamping, pre-unclamping, unclamping and 1-5-10-20 minutes after abdominal aortic unclamping. RESULTS: No significative changes of MAP, PaCO2, Vm and PI were noticed during the aortic cross-clamping period (77.5 +/- 18.5 SD minutes). During aortic unclamping Vm and MAP decreased (64 +/- 20 vs 52 +/- 20 cm/sec, p < 0.05, and 101 +/- 8 vs 80 +/- 15 mmHg, p < 0.01, respectively). At the 1th post-unclamping minute there was an increase from pre-unclamping values of Vm (75 +/- 20 cm/sec, p < 0.05) and PaCO2 (42 +/- 1.5 vs 36 +/- 2 mmHg, p < 0.05), with persistent reduction of MAP (92 +/- mmHg, p < 0.05), even more evident at the 5th post-unclamping minute (Vm = 93 +/- 25 cm/sec; PaCO2 = 46 +/- 1.2 mmHg, p < 0.001, and MAP returned to pre-unclamping value), in which there was also a decrease of PI (0.65 +/- 0.16 vs 0.78 +/- 0.2, p < 0.05). At the 10th minute Vm (83 +/- 24 cm/sec, p < 0.02) and PaCO2 (41 +/- 1.5 mmHg, p < 0.05) increments were present together with persistent reduction of PI (0.69 +/- 0.17, p < 0.05), while at the 20th post-unclamping minute also Vm, PaCO2 and PI returned to their pre-unclamping values. CONCLUSIONS: The Vm decrease at aortic unclamping might correlate with the acute changes in MAP (blood steal hypovolemia) and is likely due to an inadequate cerebral autoregulatory response to abrupt MAP changes. The arterial CO2 increase after aortic unclamping could lead to a dilation of cerebral arterioles and a rise of CBF (increase of Vm and decrease of PI). Transcranial Doppler is a simple and reliable technique for the monitoring of cerebral blood flow parameters and seems to be quite suitable for the recognition and the quantification of changes in these parameters induced by surgical manoeuvres able to produce hemodynamic instability.

Aged↗

PubMed1997

[The ultrasonographic confirmation of the role of external carotid artery in blood supply of ischemic lesion in the big cerebral hemisphere].

Using intraoperative monitoring of the blood flow linear speed in a. cerebralis media while total a. carotis interna occlusion in 10 patients the authors have concluded, that the degree of blood flow compensation in a. cerebralis media depends not only on collateral compensation possibilities by the contralateral side and rate of it inclusion, but largely-on a. carotis externa possibility on the lesion side.

Arterial Occlusive Diseases↗

PubMed1987

Hepatic cryosurgery with intraoperative ultrasound monitoring for metastatic colon carcinoma.

We utilized cryosurgery with intraoperative ultrasound (IOUS) monitoring in ten patients to treat multiple unresectable hepatic metastases from colorectal carcinoma. The liver was exposed at laparotomy, and tumors were subjected to three cycles of freezing (eight minutes each) and thawing. Freezing was monitored by IOUS, which visualized frozen tumor as a hyperechoic rim with posterior acoustic shadowing. Frozen normal liver appeared hypoechoic after thawing compared with normal unfrozen liver. There were no significant complications. The follow-up ranged from four months to 17 months (median, 7.5 months). Tumor response was documented by pathologic findings (coagulative necrosis), progressive fall of carcinoembryonic antigen levels, and computed tomographic scan evidence of necrosis and shrinkage of tumor. One patient underwent repeated laparotomy five months after cryosurgery and had the frozen lesions resected; there was no residual tumor. This study establishes the technical feasibility and antitumor response of hepatic cryosurgery and the use of IOUS for precise localization and monitoring of cryoablations.

Adult↗

PubMed2002

Intraoperative electromyographic monitoring during periacetabular osteotomy.

Periacetabular osteotomy has become the procedure of choice in many centers for the treatment of symptomatic hip dysplasia. Intraoperative real-time nerve monitoring has been advocated during acetabular fracture repair and complex total hip arthroplasties to prevent iatrogenic sciatic nerve injury. To the authors' knowledge there is no information concerning the use of intraoperative electromyographic monitoring during periacetabular osteotomy. The purpose of the current study was to investigate the use of intraoperative continuous electromyographic monitoring during periacetabular osteotomy in a relatively large consecutive series of patients as a mechanism to prevent nerve injury during surgery and as a prognostic indicator of neurologic function after periacetabular osteotomy. From September 1992 to July 1999, 140 consecutive periacetabular osteotomies were done in 127 patients at the authors' institution. There were 96 females and 31 males, with an average age of 32 years at the time of surgery. All patients had intraoperative electromyographic monitoring of femoral and sciatic innervated muscles. All patients were followed up for a minimum of 1 year, until complete resolution of neurologic deficits, or both. Thirty-six patients (26%) had abnormal electromyographic activity recorded during surgery. Seven patients (5%) had peroneal nerve deficits postoperatively including extensor hallucis longus and tibialis anterior weakness with loss of sensation in the first web space. Abnormal electromyographic activity was observed intraoperatively in five of the seven patients with postoperative deficits. Six of the seven injuries resolved completely. One patient with intraoperative electromyographic activity (0.7%) had a postoperative foot drop that persisted for greater than 1 year. There were no femoral, tibial, or obturator nerve deficits observed. Electromyographic monitoring appears to provide prediction of postoperative neurologic deficit.

Acetabulum↗

PubMed2001

[Monitoring of neurophysiologic modalities during surgery for cerebellopontine angle tumors. Personal experiments].

The purpose of intraoperative monitoring of many modalities is to save some structures of the nervous system being at risk of damaging during surgical procedures. In cerebellopontine angle (cpa) tumour cases these nervous system structures can include cranial nerves (trigeminal, facial, cochlear, accessory), motor and sensory tracts localised within brainstem, and other. Continuous registration of somatosensory and auditory evoked potentials as well as electromyography of masseter muscle, orbicular muscle of eye and trapezius muscle during procedure is the method of brainstem, cochlear tract and cranial nerves status evaluation. Direct stimulation of cranial nerves within posterior fossa using bipolar electrode is the method of facial, trigeminal and accessory nerves localisation, especially in patients with large tumours. In Department of Neurosurgery Silesian University School of Medicine for intraoperative monitoring of many modalities in cpa lesion cases Nocolet Viking IV D unit with special IOM software is employed. Authors presented own experience in such method and effect in treatment of group of 15 patients operated with electrophysiological intraoperative monitoring.

Adolescent↗

PubMed2000

Intraoperative electrophysiological monitoring of oculomotor nuclei and their intramedullary tracts during midbrain tumor surgery.

OBJECTIVE: During surgery for intrinsic midbrain lesions, we intraoperatively recorded evoked compound muscle action potentials (ECMAPs) from the extraocular muscles and evaluated how this type of intraoperative electrophysiological monitoring could minimize postoperative oculomotor nerve palsy (ptosis and/or diplopia). METHODS: The ECMAPs were recorded through a spring electrode applied to the extraocular muscle (Method 1, seven cases) or a needle electrode inserted into the superior intraorbital space (Method 2, five cases). The surgeon repeated electrical stimulations whenever tissue of unknown origin was encountered intraoperatively, and this information was used to safely guide surgical resection of the tumors. RESULTS: Using these monitoring techniques, the response-free areas were resected and the areas from which ECMAP responses were recorded were avoided. For all 12 patients, ECMAPs were successfully recorded from the extraocular muscles. Ten patients did not exhibit any postoperative deterioration of oculomotor nerve function. Two patients exhibited deterioration of oculomotor nerve function immediately after surgery, which resolved within 1 month. Equally robust ECMAPs could be recorded with Method 2, compared with Method 1. CONCLUSION: Intraoperative ECMAP recordings from the extraocular muscles precisely indicated the locations of the oculomotor nuclei and/or intramedullary oculomotor tracts. Although Method 2 is a more indirect method for recording ECMAPs than is Method 1, Method 2 was equally useful in recording ECMAPs, which seemed to be the summed potentials from the superior rectus muscle and the levator palpebrae superioris muscle. These monitoring techniques are valuable in guiding surgeons to avoid causing inadvertent harm to the oculomotor nuclei and tracts during midbrain surgery, particularly when the neuroanatomic features are distorted by the presence of tumor.

Adolescent↗

PubMed2002

Intraoperative neurophysiological monitoring in pediatric neurosurgery: why, when, how?

INTRODUCTION: This review is primarily based on peer-reviewed scientific publications and on the authors' experience in the field of intraoperative neurophysiology. The purpose is a critical analysis of the role of intraoperative neurophysiological monitoring (INM) during various neurosurgical procedures, emphasizing the aspects that mainly concern the pediatric population. Original papers related to the field of intraoperative neurophysiology were collected using medline. INM consists in monitoring (continuous "on-line" assessment of the functional integrity of neural pathways) and mapping (functional identification and preservation of anatomically ambiguous nervous tissue) techniques. We attempted to delineate indications for intraoperative neurophysiological techniques according to their feasibility and reliability (specificity and sensitivity). DISCUSSION AND CONCLUSIONS: In compiling this review, controversies about indications, methodologies and the usefulness of some INM techniques have surfaced. These discrepancies are often due to lack of familiarity with new techniques in groups from around the globe. Accordingly, internationally accepted guidelines for INM are still far from being established. Nevertheless, the studies reviewed provide sufficient evidence to enable us to make the following recommendations. (1) INM is mandatory whenever neurological complications are expected on the basis of a known pathophysiological mechanism. INM becomes optional when its role is limited to predicting postoperative outcome or it is used for purely research purposes. (2) INM should always be performed when any of the following are involved: supratentorial lesions in the central region and language-related cortex; brain stem tumors; intramedullary spinal cord tumors; conus-cauda equina tumors; rhizotomy for relief of spasticity; spina bifida with tethered cord. (3) Monitoring of motor evoked potentials (MEPs) is now a feasible and reliable technique that can be used under general anesthesia. MEP monitoring is the most appropriate technique to assess the functional integrity of descending motor pathways in the brain, the brain stem and, especially, the spinal cord. (4) Somatosensory evoked potential (SEP) monitoring is of value in assessment of the functional integrity of sensory pathways leading from the peripheral nerve, through the dorsal column and to the sensory cortex. SEPs cannot provide reliable information on the functional integrity of the motor system (for which MEPs should be used). (5) Monitoring of brain stem auditory evoked potentials remains a standard technique during surgery in the brain stem, the cerebellopontine angle, and the posterior fossa. (6) Mapping techniques (such as the phase reversal and the direct cortical/subcortical stimulation techniques) are invaluable and strongly recommended for brain surgery in eloquent cortex or along subcortical motor pathways. (7) Mapping of the motor nuclei of the VIIth, IXth-Xth and XIIth cranial nerves on the floor of the fourth ventricle is of great value in identification of "safe entry zones" into the brain stem. Techniques for mapping cranial nerves in the cerebellopontine angle and cauda equina have also been standardized. Other techniques, although safe and feasible, still lack a strong validation in terms of prognostic value and correlation with the postoperative neurological outcome. These techniques include monitoring of the bulbocavernosus reflex, monitoring of the corticobulbar tracts, and mapping of the dorsal columns. These techniques, however, are expected to open up new perspectives in the near future.

Brain Mapping↗

PubMed2004

[The usefulness of intraoperative TEE monitoring in a patient with renal cell carcinoma].

A 55-year-old man was admitted to our hospital for treatment of renal cell carcinoma. Preoperative MRI showed infradiaphragmatic extension of the tumor thrombus. However, intraoperative transesophageal echocardiography (TEE) revealed intracardiac extension of the thrombus. Therefore, the tumor thrombus was extirpated under cardiopulmonary bypass. The patient recovered without any complications. Intraoperative TEE monitoring is useful not only for the evaluation of cardiac functions but also for intraoperative diagnosis of a tumor thrombus during the operation for renal cell carcinoma.

Carcinoma, Renal Cell↗