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At least 379 records · Page 21Linked to original sources
PubMedDate not supplied

[Retraction pressure: a new parameter in intraoperative monitoring of neurosurgical patients].

The injurious effects of self-retained retractors on brain tissue during surgery were studied in patients with various neurosurgical diseases of the brain. The first part of the study was devoted to retraction pressure in neurosurgical patients. The highest values were observed in patients with abnormalities of the chiasmal-sellar area, median cranial fossa, and aneurysms of the anterior portions of Willis' circle. The second part was devoted to a retrospective analysis which revealed a high incidence of complications caused by the use of retractors in patients with tumors of the chiasmal-sellar area and median cranial fossa. In the third part we assessed the preventive effect of some methods aimed at reduction of the brain volume during surgery. Preliminary intravenous infusion of mannitol solution, puncture of the tumor cyst, ventricular and, possibly, lumbar draining were found to be prophylactically useful. Acute hyperventilation and intravenous preinjection of a saluretic were ineffective.

Brain↗
PubMed1991

Intraoperative recurrent laryngeal nerve monitoring.

Intraoperative nerve monitoring has become common for surgical procedures in which cranial or peripheral nerves may be compromised. Intraoperative monitoring of recurrent laryngeal nerve function can be accomplished by recording electromyographic activity from fine-wire electrodes placed in the vocalis muscle. The technique and instrumentation for this are adapted from those used in intraoperative facial nerve monitoring for acoustic neuroma excision. Specifically, a commercially available instrument, the XOMED-NIM provides the capability for monitoring the vocalis muscle electromyogram by means of visual and auditory display. It also provides the capability for performing evoked electromyographic tests of nerve integrity. Intraoperative monitoring of the recurrent laryngeal nerve during thyroidectomy may assist in the more precise dissection of the nerve as well as in verification of nerve integrity during the operative procedure, thus reducing the risk of injury.

Electrodes↗
PubMed1994

Investigation of a coaxial bipolar nerve stimulator for intraoperative motor nerve monitoring.

Intraoperative cranial motor nerve monitoring has improved the preservation of cranial nerve function during cerebellopontine angle and skull base surgery. Further improvements are needed to provide greater selectivity and sensitivity during intraoperative motor nerve stimulation. Use of bipolar stimulator probes has been recommended by previous investigators. The authors hypothesized that a coaxial bipolar stimulator design might provide important advantages over existing designs. This study compared the results of bipolar and monopolar stimulation using a coaxial stimulator probe in a rat model and during neurotologic procedures. The coaxial bipolar probe was superior in selectivity, thereby permitting useful multichannel monitoring. The coaxial design may also offer advantages over previous bipolar stimulator designs.

Animals↗
PubMed1988

Detailed analysis of intraoperative changes monitoring brain stem acoustic evoked potentials.

A series of 31 neurosurgical procedures in the posterior fossa monitored intraoperatively with ipsilateral brain stem acoustic evoked potentials (BAEPs) is analyzed for intraoperative potential changes. The evaluation of patients included pre- and postoperative BAEP recordings and pure tone audiometry. The series included 25 tumors, 4 neurovascular decompressions, 1 basilar artery aneurysm, and 1 arteriovenous malformation. Two intraoperative findings correlated significantly with a postoperative decrease in hearing: an amplitude reduction of more than 50% for Waves I to V and the loss of one of the waves, even if it was a wave that first appeared intraoperatively. We could attribute no significance to reversible or irreversible latency increases for all waves. The transient loss of one of the peaks followed by its reappearance was also insignificant with regard to postoperative hearing. A good prognostic sign was the intraoperative appearance of a peak undetectable on the preoperative recordings. These findings suggest that in intraoperative BAEP monitoring the observation of amplitude reduction is more important than that of latency increases. The surgeon should be informed when an amplitude reduction of more than 50% occurs before the peak is lost totally, as it is impossible to predict whether this peak will reappear intraoperatively.

Adult↗
PubMed1985

Intraoperative facial nerve monitoring.

Intraoperative evoked electromyography is an effective tool for use in locating the position of a normal facial nerve or the site of a nerve conduction block in acute facial paralysis. The technique of intraoperative evoked electromyography is described. Intraoperative stimulation of the facial nerve is a more accurate method of identifying a nerve conduction block than the site-of-lesion Schirmer's test.

Electric Stimulation↗
PubMedDate not supplied

Monitoring of brain-stem trigeminal evoked potentials. Clinical applications in posterior fossa surgery.

Brain-stem trigeminal evoked potentials (BTEPs) were monitored intraoperatively in 17 patients during posterior fossa surgery. Satisfactory BTEP recording was performed in all patients without technical problems or interfering with the activity of the operating team. The BTEP was not altered by anesthetic agents or muscle relaxants. Intraoperative monitoring of the BTEP showed wave form alterations or increasing peak latencies in 10 patients. Among these patients, the BTEP demonstrated a dynamic correlation with the surgical process in 8 instances. Two major causative surgical manipulations were identified: cerebellar retraction in 4 cases and tumor dissection from the brain-stem in 6 cases. Withholding the dissection of the tumor, readjusting a cerebellar retractor or further modifying the surgical attitude resulted in partial or complete return of the wave form in 7 patients. The BTEP at the end of surgery proved to correlate with the immediate surgical outcome in most instances. We concluded that the intraoperative monitoring of the BTEP was feasible and suggested, despite the small number of patients, a potential value in the survey of brain-stem functions during posterior fossa surgery.

Adult↗
PubMed1988

[Intraoperative electrophysiological monitoring for hearing preservation in acoustic neurinoma surgery].

Five acoustic neurinomas have been operated with hearing preservation as a goal. We monitored intraoperative brainstem auditory evoked potentials (BAEP) in all five cases, electrocochleogram (ECoG) using needle electrode in external auditory meatus in four, and compound action potentials directly recorded from the cochlear nerve (CAP VIII) in three. In all five cases the tumor was totally resected and cochlear nerve was anatomically preserved. However, in only one case useful hearing was preserved with preservation of all wave forms of the BAEP. Another patient with preservation of all wave forms of BAEP and the ECoG showed postoperative severe hearing loss. Other three patients showed postoperative severe hearing loss: only Wave I of BAEP and ECoG were preserved without preservation of the CAP VIII in one whose cochlear nerve was thought to be damaged in cerebellopontine angle cistern; Wave I of BAEP, ECoG and CAP VIII were preserved in one in whom it was suggested cochlear nerve near brainstem or cochlear nucleus was damaged; none of the BAEP, ECoG and CAP VIII was preserved in one in whom it was suggested distal cochlear nerve, or internal auditory artery was damaged. These different patterns of changes suggested that different causes for the hearing loss and difficulties in hearing preservation during acoustic neurinoma surgery. Having identified the putative mechanism of the hearing loss by monitoring those potentials, suggestions are made about how such hearing loss might be avoided. For preservation of the hearing in acoustic neurinoma surgery, all of those potentials including all wave forms of BAEP, ECoG and CAP VIII should be preserved during surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1991

[Evaluation of intraoperative transesophageal echocardiography].

With the development of medical ultrasonics, anesthesiologists have recognized the usefulness of transesophageal echocardiography as an intraoperative monitoring. Intraoperative transesophageal echocardiography is now used to monitor left ventricular function and to confirm the result of surgical correction immediately after cardiac operation. In this study, we evaluated the detectability of air embolism and the effect of hemodynamic changes on physiological mitral regurgitant flow by transesophageal Doppler echocardiography (TEDE). TEDE was more sensitive than precordial Doppler ultrasound in detecting intracardiac air. TEDE could detect air inflow to the right atrium earlier than alterations in pulmonary hemodynamics. The monitoring of intracardiac air by TEDE minimized the complication by air embolism. Regarding physiological mitral regurgitation, the degree of regurgitation increased with the elevation of BP in 70% of patients. An increase in afterload seemed to cause accidental volume loading on the left heart resulting in physiological mitral regurgitation. Intraoperative monitoring of regurgitant flow by TEDE was useful for the anesthesiologist as a guide of hemodynamic management. Transesophageal echocardiography is a useful intraoperative monitoring method regardless of its several disadvantages. With further improvement of mechanical device, transesophageal echocardiography will be more often and safely performed in operating room.

Echocardiography, Doppler↗
PubMed1996

Intraoperative end-tidal carbon dioxide levels and derived calculations correlated with outcome in trauma patients.

BACKGROUND: To determine the relationship between the prognosis of seriously injured patients requiring emergency surgery and intraoperative end-tidal CO2 variables and "excess Pco2." METHOD: Retrospective chart review of 100 seriously injured patients admitted to Detroit Receiving Hospital and requiring major surgery (mortality rate of 40%). Standard intraoperative monitoring, including continuous capnography, plus arterial blood analyses every 15 to 30 minutes during surgery. RESULTS: After resuscitation for 45 to 90 minutes, 11 patients had a systolic blood pressure < 100 mm Hg and, of these patients, 10 (91%) died. Of the remaining 89 patients, mortality rates were 53% (16/30), with an end-tidal CO2 of 22 mm Hg or less, versus 24% (14/59) with an end-tidal CO2 of 23 mm Hg or more (p = 0.011). An arterial to end-tidal Pco2 difference of 13 mm Hg or more after resuscitation was associated with an increased mortality rate (50% (20/34 vs. 18% (20/55)) (p < 0.005). The mortality rate was particularly high, with a final arterial to end-tidal Pco2 difference of 12 mm Hg or more (73% (30/41) versus 17% (10/59) (p < 0.001). A final Paco2 excess (i.e., the amount by which the Paco2 was higher than expected from the bicarbonate) > 1.0 mm Hg was also associated with an increased mortality rate ((62% (33/53) vs. 15% (7/47)) (p < 0.001). CONCLUSION: Values derived from the end-tidal CO2 and the excess Pco2 should be monitored intraoperatively in critically injured patients. Efforts should be made to improve cardiac output and adjust ventilation to maintain an end-tidal Pco2 of 25 mm Hg or more, an arterial to end-tidal CO2 difference of 12 mm Hg or less, and an excess Paco2 of 1.0 mm Hg or less.

Adult↗
PubMedDate not supplied

Morbidity and mortality following carotid surgery.

The records of 920 patients who underwent carotid endarterectomy by the same surgeon (M. D'A) between 1976 and 1989 were reviewed. Particular attention was paid to both the neurological and general complications and to how and when the neurological symptoms appeared. Among these patients, a cumulative stroke plus death rate of 3.1% was observed. Complications were classified as clamping ischemia (2.2%), postoperative embolism (1.5%), postoperative thrombosis (2.4%), and cerebral haemorrhage (0.3%). Two patients (0.2%) died from myocardial infarction. In 3.5% of patients, neurological symptoms were transient. The incidence of clamping ischemia was higher when 40 mmHg was considered as the safety limit of the back-pressure; this incidence fell by raising this limit to 50 mmHg, and introducing, in recent years, SEPs monitoring. Intraoperative monitoring of SEPs, in fact, reduced the neurological complications to 1.4%, while intraoperative angiography reduced the need for intraoperative reoperation from 10% to 2%. The use of antiplatelet drugs and an accurate surgical technique are useful steps in the prevention of postoperative embolism or thrombosis.

Cerebrovascular Disorders↗
PubMed1987

Intraoperative use of dermatomal somatosensory-evoked potentials in lumbar stenosis surgery.

This report concerns the use of dermatomal somatosensory-evoked potentials (DSEPs) for intraoperative monitoring in the surgical management of a group of patients with lumbar spinal stenosis. Thirty patients with lumbar spinal stenosis underwent preoperative evaluation by DSEPs by use of electrical stimulation of the skin corresponding to the L4, L5, and S1 dermatomes. The specific dermatome to be monitored intraoperatively was selected by correlating those data with physical and radiographic findings and, in certain cases, the results of selective nerve root blocks. Intraoperative baseline (predecompression) DSEP values were obtained after positioning the patient on the operative frame. Monitoring was performed during surgery and post-decompression values were obtained after neural decompression. For six cases of unilateral nerve root decompression, an average 9-msec decrease in latency was noted on the operated side and a 3-msec decrease on the nonoperated side. For 24 cases of bilateral decompression, an average 8-9-msec decrease in latency was noted bilaterally. This method has been found helpful in assessing the adequacy of neural decompression intraoperatively.

Adult↗