Intraoperative monitoring of brain-stem auditory evoked potentials

1982 ◽  
Vol 57 (5) ◽  
pp. 674-681 ◽  
Author(s):  
Betty L. Grundy ◽  
Peter J. Jannetta ◽  
Phyllis T. Procopio ◽  
Agnes Lina ◽  
J. Robert Boston ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
Brain Stem ◽  
Auditory Nerve ◽  
Intraoperative Monitoring ◽  
Cerebellopontine Angle ◽  
Auditory Evoked Potentials ◽  
Irreversible Loss ◽  
Content Type ◽  
Complete Obliteration ◽  
Fine Print

✓ Brain-stem auditory evoked potentials (BAEP) were monitored during 54 neurosurgical operations in the cerebellopontine angle. The BAEP were irreversibly obliterated in five patients who required deliberate section of the auditory nerve. Technical difficulties interfered with monitoring in three cases, and three patients had deafness and absent BAEP preoperatively. Reversible alterations in BAEP were seen during 32 operations, with recovery after as long as 177 minutes of virtually complete obliteration. Changes in BAEP were associated with surgical retraction, operative manipulation, positioning of the head and neck for retromastoid craniectomy, and the combination of hypocarbia and moderate hypotension. In 19 cases, waveforms improved after specific interventions made by the surgeon or anesthesiologist because of deteriorating BAEP. In 13 other cases, BAEP recovered after maneuvers not specifically related to the electrophysiological monitoring, most often completion of operative manipulation. Whenever BAEP returned toward normal by the end of anesthesia, even after transient obliteration, hearing was preserved. Irreversible loss of BAEP occurred only when the auditory nerve was deliberately sacrificed. The authors conclude that monitoring of BAEP may help prevent injury to the auditory nerve and brain stem during operations in the cerebellopontine angle.

A comparative study of brain-stem auditory evoked potentials and blink reflexes in posterior fossa tumor patients

1988 ◽  
Vol 69 (5) ◽  
pp. 660-668 ◽  
Author(s):  
Mehmet Zileli ◽  
Fethi İdiman ◽  
Tufan Hiçdönmez ◽  
İzzet Övül ◽  
Erdem Tunçbay
Keyword(s):  
Evoked Potentials ◽  
Brain Stem ◽  
Posterior Fossa ◽  
Cerebellopontine Angle ◽  
Auditory Evoked Potentials ◽  
Lesion Group ◽  
Control Group ◽  
Posterior Fossa Tumors ◽  
Content Type ◽  
Fine Print

✓ Brain-stem auditory evoked potentials (BAEP's) and blink reflexes (BR's) were recorded from 40 patients with clinical and radiological evidence of posterior fossa tumors. They were examined in three groups according to the anatomical location of the lesion: Group A included 15 patients with midline tumors; Group B included 14 patients with cerebellar hemispheric tumors; and Group C included 11 patients with cerebellopontine angle (CPA) tumors. More of the 40 patients had BAEP abnormalities (32) than BR abnormalities (24). All of the 11 patients with CPA tumors had some kind of BAEP and BR abnormalities. The 14 patients with cerebellar tumors showed the next most frequent abnormalities: 12 related to the BAEP's and seven to the BR's. The 15 patients with midline tumors showed the least number of abnormalities: nine related to BAEP's and six to the BR's. In the analysis of BAEP wave latencies and interpeak latencies, a wave III latency delay occurred in all groups; latencies of waves IV and V were more significantly delayed in patients with CPA and cerebellar hemispheric tumors, and the interpeak latencies of waves III–V and I–V were markedly prolonged only in patients with CPA tumors (p < 0.01). In all tumor groups, early response (R1) of BR's was significantly delayed in comparison to a healthy volunteer control group (p < 0.01), but R1 was more pronounced in cases of CPA tumors when compared with the other tumor groups. Although significant delays in direct and consensual late reflex components (R2) of BR's were noted in comparison to the control group, this delay could not differentiate one tumor group from another. It can be concluded that, while these tests reflect the functions of different cranial nerves and brain-stem tracts, BAEP monitoring is more sensitive than BR testing for the detection of brain-stem involvement in posterior fossa tumors. Cerebellopontine angle tumors almost always cause severe abnormalities in both tests. Cerebellar hemispheric tumors and midline tumors cause fewer changes in both BAEP's and BR's.

Monitoring Auditory Nerve Potentials during Operations in the Cerebellopontine Angle

1984 ◽  
Vol 92 (4) ◽  
pp. 434-439 ◽  
Author(s):  
Aage R. Øller ◽  
Peter J. Jannetta
Keyword(s):  
Hearing Loss ◽  
Evoked Potentials ◽  
Brain Stem ◽  
Microvascular Decompression ◽  
Auditory Nerve ◽  
Cerebellopontine Angle ◽  
Auditory Evoked Potentials ◽  
Cranial Nerves

Direct monitoring of auditory nerve potentials was performed in 19 patients undergoing retromastoid craniectomy and microvascular decompression of cranial nerves. In addition, brain stem auditory evoked potentials (BSEPs) were monitored in these patients. No patient suffered significant hearing loss. Direct monitoring of auditory nerve potentials complements the recording of BSEPs because the auditory nerve potentials can be visualized without averaging many responses. Therefore the effect of any intraoperative manipulation that is harmful to the auditory nerve can be detected instantaneously.

Measurements of brain-stem auditory evoked potentials in patients with spontaneous intracerebral hemorrhage

1984 ◽  
Vol 60 (3) ◽  
pp. 548-552 ◽  
Author(s):  
Christianto B. Lumenta
Keyword(s):  
Glasgow Coma Scale ◽  
Intracerebral Hemorrhage ◽  
Evoked Potentials ◽  
Brain Stem ◽  
Auditory Evoked Potentials ◽  
Spontaneous Intracerebral Hemorrhage ◽  
Content Type ◽  
Different Types ◽  
The Brain ◽  
Fine Print

✓ Brain-stem auditory evoked potentials (BAEP's) were recorded in 19 patients with spontaneous intracerebral hemorrhage. More than half of the patients were deeply comatose. There was no correlation between BAEP changes and different types of spontaneous intracerebral hemorrhage or between BAEP's and coma grading by the Glasgow Coma Scale. However, BAEP's were a significant prognostic aid in these cases and useful in indicating the level of the brain-stem lesion.

Auditory evoked potentials recorded from the cochlear nucleus and its vicinity in man

1983 ◽  
Vol 59 (6) ◽  
pp. 1013-1018 ◽  
Author(s):  
Aage R. Møller ◽  
Peter J. Jannetta
Keyword(s):  
Evoked Potentials ◽  
Brain Stem ◽  
Cochlear Nucleus ◽  
Auditory Nerve ◽  
Auditory Evoked Potentials ◽  
Auditory Pathway ◽  
Content Type ◽  
Negative Peak ◽  
Auditory Brain Stem ◽  
Stimulation Of

✓ Intracranial responses from the auditory nerve and the cochlear nucleus were recorded from patients undergoing neurosurgical operations during which these structures were exposed. Responses to stimulation of the ipsilateral ear with short tonebursts from the vicinity of the cochlear nucleus show a large surface-negative peak, the latency of which is close to that of peak III in the auditory brain-stem evoked potentials recorded from scalp electrodes. There was also a response to contralateral stimulation, smaller in amplitude and with a longer latency. It is concluded that the cochlear nucleus is the main generator of peak III responses, and that structures of the ascending auditory pathway that are more central than the cochlear nucleus are unlikely to contribute to wave III of the auditory brain-stem evoked potentials.

Use of intraoperative auditory evoked potentials to preserve hearing in unilateral acoustic neuroma removal

1984 ◽  
Vol 61 (5) ◽  
pp. 938-948 ◽  
Author(s):  
Robert G. Ojemann ◽  
Robert A. Levine ◽  
William M. Montgomery ◽  
Patricia McGaffigan
Keyword(s):  
Evoked Potentials ◽  
Brain Stem ◽  
Auditory Evoked Potentials ◽  
Compound Action Potential ◽  
Speech Discrimination ◽  
Sound Perception ◽  
Content Type ◽  
Increased Risk ◽  
The Status ◽  
Fine Print

✓ Twenty-two patients with unilateral acoustic neuromas and preoperative speech discrimination scores of 35% or more had intraoperative monitoring of the electrocochleogram (ECoG) using a transtympanic electrode, and of the brain-stem auditory evoked potentials (BAEP's) using scalp electrodes. Rapid feedback was provided about the status of the cochlear microphonics from the hair cells of the inner ear (CM of the ECoG), the compound action potential of the auditory nerve (N-1 of the ECoG or Wave I of the BAEP's) and the potentials from the lower brain stem (Wave V of the BAEP's). All patients had total removal of the tumor. In 21, the cochlear nerve was anatomically preserved, and 20 had good postoperative facial nerve function. Correlation of tumor size with postoperative hearing was as follows: discrimination scores of more than 35% in three of four patients with 1-cm tumors, two of eight with 1.5-cm tumors, two of six with 2- to 2.5-cm tumors, and one of four with tumors of 3 cm or more. Two other patients with 1.5-cm tumors had discrimination scores of less than 35%, and one patient with a 2-cm tumor had only sound perception. In two patients, the discrimination scores improved. At the end of the operation, all patients with hearing had a detectable N-1, and, when recorded, CM. All but one patient with no hearing had lost N-1, and CM was absent or reduced. Unless Wave V was unchanged, it was a poor predictor of postoperative hearing, and its absence did not preclude preservation of good hearing. The electrophysiological changes during each stage of the operation were analyzed and correlated with events during surgery. Areas in which there was an increased risk of loss of the potentials were determined. In some patients monitoring was unnecessary, because either there were no significant changes or the changes were abrupt and no recovery occurred. However, in other patients, monitoring alerted the surgeon to a possible problem and the method of dissection was altered. Possible mechanisms of hearing loss were suggested from the changes in the recordings.

Intraoperative monitoring of brain-stem auditory evoked potentials

1982 ◽  
Vol 57 (3) ◽  
pp. 341-348 ◽  
Author(s):  
Peter A. Raudzens ◽  
Andrew G. Shetter
Keyword(s):  
Evoked Potentials ◽  
Brain Stem ◽  
Auditory Evoked Potentials ◽  
Neurological Deficits ◽  
Additional Patient ◽  
Content Type ◽  
Intracranial Surgery ◽  
Surgical Measures ◽  
Evoked Potential Monitoring ◽  
Operating Surgeon

✓ Intraoperative brain-stem auditory evoked potentials (BAEP's) were monitored in 46 patients undergoing intracranial surgery for a variety of pathological conditions to determine whether this technique was capable of providing useful information to the operating surgeon. Intraoperative BAEP's were unchanged throughout surgery in 34 patients (74%), and these individuals had no postoperative hearing deficits. Four patients (9%) developed an abrupt ipsilateral loss of all waveform components beyond Wave I and had postoperative evidence of a pronounced hearing loss in the affected ear. An additional patient demonstrated BAEP loss contralateral to the side of surgery, and this was associated with subsequent signs of severe brain-stem dysfunction. Seven patients (15%) developed intraoperative delays of BAEP waveform latency values, but maintained recognizable waveforms beyond Wave I. Postoperatively, their hearing was either normal or mildly impaired, and there were no indications of other brain-stem abnormalities. This group represents the individuals who may have been benefited by evoked potential monitoring, since corrective surgical measures were taken when latency delays were observed. Intraoperative BAEP's can be reliably and routinely recorded in an operating room environment. They provide a good predictor of postoperative auditory status, and may have prevented permanent neurological deficits in a small segment of patients by alerting the surgeon to potentially reversible abnormalities.

Arteriovenous malformations in the posterior fossa

1977 ◽  
Vol 47 (1) ◽  
pp. 50-56 ◽  
Author(s):  
Hiroshi Matsumura ◽  
Yasumasa Makita ◽  
Kuniyuki Someda ◽  
Akinori Kondo
Keyword(s):  
Arteriovenous Malformation ◽  
Brain Stem ◽  
Posterior Fossa ◽  
Arteriovenous Malformations ◽  
Cerebellopontine Angle ◽  
Anterior Part ◽  
Content Type ◽  
The Brain ◽  
Fine Print

✓ We have operated on 12 of 14 cases of arteriovenous malformation (AVM) in the posterior fossa since 1968, with one death. The lesions were in the cerebellum in 10 cases (three anteromedial, one central, three lateral, and three posteromedial), and in the cerebellopontine angle in two; in two cases the lesions were directly related to the brain stem. The AVM's in the anterior part of the cerebellum were operated on through a transtentorial occipital approach.

Transcranial electrical stimulation through screw electrodes for intraoperative monitoring of motor evoked potentials

2004 ◽  
Vol 100 (1) ◽  
pp. 155-160 ◽  
Author(s):  
Katsushige Watanabe ◽  
Takashi Watanabe ◽  
Akio Takahashi ◽  
Nobuhito Saito ◽  
Masafumi Hirato ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Motor Cortex ◽  
Evoked Potentials ◽  
Intraoperative Monitoring ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Transcranial Electrical Stimulation ◽  
Content Type ◽  
Motor Pathways ◽  
Fine Print

✓ The feasibility of high-frequency transcranial electrical stimulation (TES) through screw electrodes placed in the skull was investigated for use in intraoperative monitoring of the motor pathways in patients who are in a state of general anesthesia during cerebral and spinal operations. Motor evoked potentials (MEPs) were elicited by TES with a train of five square-wave pulses (duration 400 µsec, intensity ≤ 200 mA, frequency 500 Hz) delivered through metal screw electrodes placed in the outer table of the skull over the primary motor cortex in 42 patients. Myogenic MEPs to anodal stimulation were recorded from the abductor pollicis brevis (APB) and tibialis anterior (TA) muscles. The mean threshold stimulation intensity was 48 ± 17 mA for the APB muscles, and 112 ± 35 mA for the TA muscles. The electrodes were firmly fixed at the site and were not dislodged by surgical manipulation throughout the operation. No adverse reactions attributable to the TES were observed. Passing current through the screw electrodes stimulates the motor cortex more effectively than conventional methods of TES. The method is safe and inexpensive, and it is convenient for intraoperative monitoring of motor pathways.

Vascular malformations of the brain stem

1989 ◽  
Vol 70 (6) ◽  
pp. 847-852 ◽  
Author(s):  
Douglas Chyatte
Keyword(s):  
Brain Stem ◽  
Vascular Malformation ◽  
Vascular Malformations ◽  
Surgical Removal ◽  
Content Type ◽  
Appropriate Treatment ◽  
Complete Obliteration ◽  
Time Of Presentation ◽  
The Brain ◽  
Fine Print

✓ Vascular malformations of the brain stem are unusual lesions that may pose a diagnostic and therapeutic challenge. Seven patients with vascular malformations involving the brain stem were evaluated; six were treated surgically, with complete obliteration of the lesion in five patients. In five patients symptoms developed only after a hemorrhage had occurred, and three of these suffered a rebleed before appropriate treatment was given. Angiography failed to demonstrate lesions in three cases, which did not appear to protect from repeat hemorrhage since two of the three rebled. There were no operative deaths, and no patients were made permanently worse after surgery. Useful recovery occurred commonly after appropriate treatment and appeared to be possible even in patients who had suffered a catastrophic neurological deficit at the time of presentation. These data indicate that surgical removal of the lesion may be warranted in some patients with symptomatic brain-stem vascular malformation.

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