Cochlear nerve injuries caused by cerebellopontine angle manipulations

1987 ◽  
Vol 67 (2) ◽  
pp. 244-249 ◽  
Author(s):  
Tetsuji Sekiya ◽  
Aage R. Møller
Keyword(s):  
Cerebellopontine Angle ◽  
Morphological Changes ◽  
Cochlear Nerve ◽  
Histological Changes ◽  
Content Type ◽  
Eighth Nerve ◽  
Vasa Nervorum ◽  
Electrophysiological Responses ◽  
Compound Action Potentials ◽  
Fine Print

✓ Changes in the response from the cochlear nerve in dogs resulting from cerebellopontine angle (CPA) manipulations were correlated with histological changes in the nerve. The aim of this study was to determine the mechanisms underlying hearing deficits incurred as a result of manipulations in the CPA. Compound action potentials (CAP) were recorded from the cochlear nerve in response to click stimulation before, during, and after cerebellar and eighth nerve retractions were performed under anesthesia. The retractions were carried out to elicit different degrees of change in the latency and waveform of the CAP. About 30 minutes after completion of the manipulations, the dogs were perfused with a fixative and their cochlear nerves and brain stems were prepared for histological studies. The results showed that retraction of the eighth nerve caused a disintegration of the myelin sheath, and there were multiple and extensive foci of petechial hemorrhage and thromboses of the vasa nervorum of the cochlear nerve. In two dogs in which retraction was carried to a point at which the N2 peak of the CAP was abruptly obliterated, there was a separation of the central and peripheral myelin junction (Obersteiner-Redlich (OR) zone) and bleeding from the vasa nervorum at the OR zone. In the dogs in which the changes in the CAP had almost recovered before fixative perfusion, there were petechial hemorrhages within the cochlear nerve trunk, thus showing that improvement of electrophysiological responses may not always correlate with the absence of morphological changes.

Preservation of hearing in patients undergoing excision of acoustic neuromas and other cerebellopontine angle tumors

1985 ◽  
Vol 63 (2) ◽  
pp. 168-174 ◽  
Author(s):  
Charles H. Tator ◽  
Julian M. Nedzelski
Keyword(s):  
Tumor Size ◽  
Cerebellopontine Angle ◽  
Internal Auditory Canal ◽  
Hearing Preservation ◽  
Cochlear Nerve ◽  
Consecutive Series ◽  
Speech Discrimination ◽  
Content Type ◽  
Acoustic Neuromas ◽  
Fine Print

✓ Microsurgical techniques have made it possible to identify and preserve the cochlear nerve from its origin at the brain stem and along its course through the internal auditory canal in patients undergoing removal of small or medium-sized acoustic neuromas or other cerebellopontine angle (CPA) tumors. In a consecutive series of 100 patients with such tumors operated on between 1975 and 1981, an attempt was made to preserve the cochlear nerve in 23. The decision to attempt to preserve hearing was based on tumor size and the degree of associated hearing loss. In cases of unilateral acoustic neuroma, the criteria for attempted preservation of hearing were tumor size (2.5 cm or less), speech reception threshold (50 dB or less), and speech discrimination score (60% or greater). In patients with bilateral acoustic neuromas or tumors of other types, the size and hearing criteria were significantly broadened. All patients were operated on through a suboccipital approach. Hearing was preserved postoperatively in six (31.6%) of the 19 patients with unilateral acoustic neuromas, although the cochlear nerve was preserved in 16. Of the six patients with postoperative hearing, three retained excellent hearing, and the other three had only sound awareness and poor discrimination. Hearing was preserved in three cases with other CPA tumors, including an epidermoid cyst and small petrous meningiomas in the internal auditory canal. Of the two cases with bilateral tumors, hearing was preserved in one. Of the 23 patients in whom hearing preservation was attempted, nine (39.1%) had some postoperative hearing, which in six was equal to or better than the preoperative level. Thus, it is worthwhile to attempt hearing preservation in selected patients with CPA tumors.

Eighth nerve lipoma

1980 ◽  
Vol 53 (3) ◽  
pp. 397-400 ◽  
Author(s):  
William C. Mattern ◽  
Robert E. Blattner ◽  
James Werth ◽  
Robert Shuman ◽  
Solomon Bloch ◽  
...  
Keyword(s):  
Cranial Nerve ◽  
Cerebellopontine Angle ◽  
Eighth Cranial Nerve ◽  
Content Type ◽  
Postoperative Course ◽  
Eighth Nerve ◽  
Clinical Diagnostic ◽  
The Right ◽  
Fine Print

✓ A case of lipoma of the right eighth cranial nerve in the cerebellopontine angle (CPA) is presented. The patient had a clinical, diagnostic, surgical, and postoperative course similar to that of patients with other small CPA tumors. The literature on this rare CPA tumor is reviewed and discussed.

Prevention of cerebral vasospasm after SAH with a thromboxane synthetase inhibitor, OKY-1581

1982 ◽  
Vol 57 (1) ◽  
pp. 74-82 ◽  
Author(s):  
Tomio Sasaki ◽  
Susumu Wakai ◽  
Takao Asano ◽  
Kintomo Takakura ◽  
Keiji Sano
Keyword(s):  
Cerebral Vasospasm ◽  
Morphological Changes ◽  
Content Type ◽  
Synthetase Inhibitor ◽  
Thromboxane Synthetase Inhibitor ◽  
Thromboxane Synthetase ◽  
Basilar Arteries ◽  
Blood Injection ◽  
Subarachnoid Blood ◽  
Fine Print

✓ The efficacy of thromboxane synthetase inhibitor in the prevention of cerebral vasospasm after subarachnoid hemorrhage (SAH) was evaluated in a prolonged experiment using dogs. Changes in the diameter of the basilar artery were followed by angiography, and morphological changes were studied by photomicroscopy and electron microscopy. As a thromboxane synthetase inhibitor, OKY-1581 (sodium-(E)-3-(4(-3-pyridylmethyl)phenyl)-2-methylacrylate)was used. Dogs received intravenous injections of 160 mg of OKY-1581 dissolved in 2 ml of physiological saline immediately after subarachnoid blood injection. Subsequently, the animals received continuous intravenous infusion of the drug at the rate of 4 gm/50 ml/24 hours until sacrifice 4 days after induction of SAH. Control dogs received subarachnoid blood injection without treatment with OKY-1581. Angiographic examination revealed that the late spasm was almost completely abolished by the treatment with OKY-1581. Early spasm was also prevented, but the drug's effect was less prominent than it was on the late spasm. Morphological study revealed degenerative changes in the endothelium and myonecrotic changes in the tunica media following SAH in the basilar arteries of the treated as well as the untreated dogs. However, corrugation of the internal elastic lamina was almost completely absent in the treated dogs. The above results indicate that a disproportionate synthesis of thromboxane A2 plays an important role in the evolution of chronic cerebral vasospasm following SAH, and that drugs such as OKY-1581 that selectively inhibit thromboxane synthetase might be useful in the prevention of vasospasm.

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.

The use of tissue culture in differentiation between angioblastic meningioma and hemangiopericytoma

1971 ◽  
Vol 34 (3) ◽  
pp. 341-348 ◽  
Author(s):  
Jans Muller ◽  
John Mealey
Keyword(s):  
Tissue Culture ◽  
Tumor Cells ◽  
Cerebellopontine Angle ◽  
Content Type ◽  
Angioblastic Meningioma ◽  
Fine Print

✓ A solid, extrinsic hemangiopericytoma of the cerebellopontine angle was studied histologically and by means of tissue culture. The explanted tumor cells formed classic meningiomatous whorls indicative of the meningeal derivation of this neoplasm. Whorls were entirely absent in the histological preparations, however. The cases reported under the diagnosis of intracranial hemangiopericytoma and angioblastic meningioma have been reviewed; no valid histological distinction between these two types could be made.

Antitumor effects of antiprogesterones on human meningioma cells in vitro and in vivo

1994 ◽  
Vol 80 (3) ◽  
pp. 527-534 ◽  
Author(s):  
Yasuhiro Matsuda ◽  
Keiichi Kawamoto ◽  
Katsuzo Kiya ◽  
Kaoru Kurisu ◽  
Kazuhiko Sugiyama ◽  
...  
Keyword(s):  
Marked Reduction ◽  
Tumor Volume ◽  
Collagen Gel ◽  
Antitumor Effects ◽  
Histological Changes ◽  
Content Type ◽  
The Relationship ◽  
Fine Print

✓ The presence of the progesterone receptor (PR) in meningioma tissue has been confirmed by previous investigations. Studies have shown that the antiprogesterone drug, mifepristone, is a potent agent that inhibits the growth of cultured meningioma cells and reduces the size of meningiomas in experimental animal models and humans. However, these studies have not fully examined the relationship between the antitumor effects of an antiprogesterone agent and the expression of the PR. The present study examined the antitumor effects of mifepristone and a new potent antiprogesterone agent, onapristone; a correlation between the antitumor effects of these antiprogesterones and the presence of PR's in meningiomas in vitro and in vivo was also investigated. Meningioma tissue surgically removed from 13 patients was used in this study. In the in vitro arm of the study, mifepristone and onapristone exhibited cytostatic and cytocidal effects against cultured meningioma cells, regardless of the presence or absence of PR's; however, three PR-negative meningiomas showed no response to any dose of mifepristone and/or onapristone. In the in vivo arm, meningioma cells, embedded in a collagen gel, were implanted into the renal capsules of nude mice. Antiprogesterone treatment resulted in a marked reduction of the tumor volume regardless of the presence or absence of PR's. No histological changes in the meningioma cells suggestive of necrosis or apoptosis were detected in any of the mice treated with antiprogesterones. These findings suggest that mifepristone and onapristone have an antitumor effect against meningioma cells via the PR's and/or another receptor, such as the glucocorticoid receptor.

The effect of gamma knife irradiation on functions of striatum in rats

2005 ◽  
Vol 102 ◽  
pp. 42-48 ◽  
Author(s):  
Osamu Tokumaru ◽  
Mihoko Tomida ◽  
Yoko Katayama ◽  
Mootohiro Hayashi ◽  
Yoriko Kawakami ◽  
...  
Keyword(s):  
Gamma Knife ◽  
Time Course ◽  
Magnetic Resonance Images ◽  
High Dose ◽  
Nigrostriatal Pathway ◽  
Histological Changes ◽  
Dorsoventral Axis ◽  
Target Region ◽  
Content Type ◽  
Fine Print

Object.An animal model has been developed to study the effect of gamma knife surgery(GKS) on cerebral function.Methods.A rat was fixed in a newly developed Régis—Valliccioni frame that enables the target region to be planned directly on the magnetic resonance images. The left striatum was irradiated with 150 Gy via a 4-mm collimator of the Leksell gamma knife. Apomorphine (dopamine agonist) was administered to elicit a circling behavior (apomorphine test) after the GKS so as to examine the time course of the changes in dopaminergic functions of irradiated striatum. After a series of behavioral analyses, irradiated brains were subjected to histological examination.Necrosis was observed in the irradiated area surrounded by hemorrhage and gliosis. The distance between the histologically estimated and planned centers of the irradiation areas was 1.0 ± 0.5 mm. The extent of the distance was due to errors along dorsoventral axis. The distribution of the irradiation areas influenced the activity and the circling behaviors in apomorphine test, which was suggestive of involvement of the nigrostriatal pathway.Conclusions.Targeting by using the Régis—Valliccioni frame was very accurate compared with targeting with coordinates based on brain maps used hitherto. Although targeting improved the accuracy, further effort will still be necessary to reduce errors along dorsoventral axis. The apomorphine test indicated a reduced dopaminergic function of the irradiated area including striatum, which accompanied histological changes after a high dose of irradiation (150 Gy).

Acoustic neuroma with malignant transformation

2001 ◽  
Vol 95 (3) ◽  
pp. 518-521 ◽  
Author(s):  
Kenichiro Hanabusa ◽  
Atsunori Morikawa ◽  
Tetsuya Murata ◽  
Waro Taki
Keyword(s):  
Malignant Transformation ◽  
Initial Treatment ◽  
Cerebellopontine Angle ◽  
Residual Tumor ◽  
Initial Operation ◽  
Content Type ◽  
Histological Studies ◽  
Mitotic Figures ◽  
Causal Sequence ◽  
Fine Print

✓ The authors describe the case of a 57-year-old woman who had a right-sided hearing disturbance that had remained untreated for 1 year. The diagnosis was of a right cerebellopontine angle tumor, and the patient underwent its removal via retrosigmoid approach. Pathologically, the tumor was a typical benign neuroma. Growth of residual tumor was detected 4 years after the initial operation, and it was treated with gamma knife surgery (GKS). Six months later, the tumor had grown, and the patient underwent surgery via a combined retrosigmoid—translabyrinthine approach. Abnormal mitotic figures were observed on histological studies, indicating that the tumor had become malignant. Thereafter, the tumor grew rapidly, and the patient died 6.5 years after the initial treatment. It cannot be ruled out that GKS affected the outcome, but the causal sequence was unclear. Because such a patient is rare, documentation of the case was considered clinically important.

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.

Continuous electromyography monitoring of motor cranial nerves during cerebellopontine angle surgery

2000 ◽  
Vol 93 (4) ◽  
pp. 586-593 ◽  
Author(s):  
Johann Romstöck ◽  
Christian Strauss ◽  
Rudolf Fahlbusch
Keyword(s):  
Detailed Analysis ◽  
Cranial Nerve ◽  
Cerebellopontine Angle ◽  
Operative Procedure ◽  
Cranial Nerves ◽  
Postoperative Outcome ◽  
Lower Cranial Nerve ◽  
Content Type ◽  
Lower Cranial Nerves ◽  
Fine Print

Object. Electromyography (EMG) monitoring is expected to reduce the incidence of motor cranial nerve deficits in cerebellopontine angle surgery. The aim of this study was to provide a detailed analysis of intraoperative EMG phenomena with respect to their surgical significance.Methods. Using a system that continuously records facial and lower cranial nerve EMG signals during the entire operative procedure, the authors examined 30 patients undergoing surgery on acoustic neuroma (24 patients) or meningioma (six patients). Free-running EMG signals were recorded from muscles targeted by the facial, trigeminal, and lower cranial nerves, and were analyzed off-line with respect to waveform characteristics, frequencies, and amplitudes. Intraoperative measurements were correlated with typical surgical maneuvers and postoperative outcomes.Characteristic EMG discharges were obtained: spikes and bursts were recorded immediately following the direct manipulation of a dissecting instrument near the cranial nerve, but also during periods when the nerve had not yet been exposed. Bursts could be precisely attributed to contact activity. Three distinct types of trains were identified: A, B, and C trains. Whereas B and C trains are irrelevant with respect to postoperative outcome, the A train—a sinusoidal, symmetrical sequence of high-frequency and low-amplitude signals—was observed in 19 patients and could be well correlated with additional postoperative facial nerve paresis (in 18 patients).Conclusions. It could be demonstrated that the occurrence of A trains is a highly reliable predictor for postoperative facial palsy. Although some degree of functional worsening is to be expected postoperatively, there is a good chance of avoiding major deficits by warning the surgeon early. Continuous EMG monitoring is superior to electrical nerve stimulation or acoustic loudspeaker monitoring alone. The detailed analysis of EMG-waveform characteristics is able to provide more accurate warning criteria during surgery.

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