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.

Hearing preservation in acoustic neuroma surgery: importance of adhesion between the cochlear nerve and the tumor

2002 ◽  
Vol 97 (2) ◽  
pp. 337-340 ◽  
Author(s):  
Takuzou Moriyama ◽  
Takanori Fukushima ◽  
Katsuyuki Asaoka ◽  
Pierre-Hugues Roche ◽  
David M. Barrs ◽  
...  
Keyword(s):  
Acoustic Neuroma ◽  
Hearing Preservation ◽  
Cochlear Nerve ◽  
Significant Prognostic Factor ◽  
Speech Discrimination ◽  
Middle Fossa ◽  
Content Type ◽  
Middle Fossa Approach ◽  
Acoustic Neuromas ◽  
Fine Print

Object. To evaluate the possible prognostic factors for hearing preservation, the authors retrospectively reviewed the results of 30 consecutive acoustic neuroma operations in which hearing preservation was attempted, in a total series of 63 acoustic neuromas. Methods. Intracanalicular tumors or those that extended less than 3 mm outside the porus acusticus (10 cases) were resected via the middle fossa approach. The retrosigmoid approach was used for tumors exceeding the limits for the middle fossa approach (20 cases). Overall, hearing was preserved (pure tone average ≤ 50 dB and speech discrimination score ≥ 50%) in 21 patients (70%). There were 11 patients with severe adhesion between the cochlear nerve and tumor capsule, and 19 without. Hearing was preserved postoperatively in only two (18.2%) of 11 patients with severe adhesion, whereas all 19 without severe adhesion had hearing preservation. Conclusions. The presence or absence of severe adhesion in the interface between the cochlear nerve and the tumor might be the most significant prognostic factor for hearing preservation postsurgery.

Correlation between auditory function and internal auditory canal pressure in patients with vestibular schwannomas

2002 ◽  
Vol 96 (5) ◽  
pp. 872-876 ◽  
Author(s):  
Samir B. Lapsiwala ◽  
G. Mark Pyle ◽  
Ann W. Kaemmerle ◽  
Frank J. Sasse ◽  
Behnam Badie
Keyword(s):  
Hearing Loss ◽  
Tumor Growth ◽  
Tumor Size ◽  
Internal Auditory Canal ◽  
Auditory Evoked Potential ◽  
Cochlear Nerve ◽  
Content Type ◽  
Vascular Compromise ◽  
Brainstem Response ◽  
Fine Print

Object. Hearing loss is the most common presenting symptom in patients who harbor a vestibular schwannoma (VS). Although mechanical injury to the cochlear nerve and vascular compromise of the auditory apparatus have been proposed, the exact mechanism of this hearing loss remains unclear. To test whether pressure on the cochlear nerve from tumor growth in the internal auditory canal (IAC) is responsible for this clinical finding, the authors prospectively evaluated intracanalicular pressure (ICaP) in patients with VS and correlated this with preoperative brainstem response. Methods. In 40 consecutive patients undergoing a retrosigmoid—transmeatal approach for tumor excision, ICaP was measured by inserting a pressure microsensor into the IAC before any tumor manipulation. Pressure recordings were correlated with tumor size and preoperative auditory evoked potential (AEP) recordings. The ICaP, which varied widely among patients (range 0–45 mm Hg), was significantly elevated in most patients (median 16 mm Hg). Although these pressure measurements directly correlated to the extension of tumor into the IAC (p = 0.001), they did not correlate to total tumor size (p = 0.2). In 20 patients in whom baseline AEP recordings were available, the ICaP directly correlated to wave V latency (p = 0.0001), suggesting that pressure from tumor growth in the IAC may be responsible for hearing loss in these patients. Conclusions. Tumor growth into the IAC results in elevation of ICaP and may play a role in hearing loss in patients with VS. The relevance of these findings to the surgical treatment of these tumors is discussed.

Preservation of hearing in surgery for acoustic neuromas

1993 ◽  
Vol 78 (6) ◽  
pp. 864-870 ◽  
Author(s):  
Michael E. Glasscock ◽  
James W. Hays ◽  
Lloyd B. Minor ◽  
David S. Haynes ◽  
Vincent N. Carrasco
Keyword(s):  
Hearing Preservation ◽  
Middle Cranial Fossa ◽  
Senior Author ◽  
Speech Discrimination ◽  
Content Type ◽  
Auditory Evoked Response ◽  
Surgical Access ◽  
Acoustic Neuromas ◽  
Cranial Fossa ◽  
Fine Print

✓Preservation of hearing was attempted in 161 cases of histologically confirmed acoustic neuroma removed by the senior author between January 1, 1970, and September 30, 1991. There were 136 patients with unilateral tumors: 22 patients had bilateral tumors (neurofibromatosis 2) and underwent a total of 25 procedures. Hearing was initially preserved in 35% of patients with unilateral tumors and in 44% of those with bilateral tumors. Results are reported in terms of pre- and postoperative pure tone average and speech discrimination scores. Surgical access to the tumor was obtained via middle cranial fossa and suboccipital approaches. The latter has been used more often over the past 5 years because of a lower associated incidence of transient facial paresis. Persistent postoperative headaches have been the most common complication following the suboccipital approach. The results of preoperative brain-stem auditory evoked response (BAER) studies were useful in predicting the outcome of hearing preservation attempts. Patients with intact BAER waveform morphology and normal or delayed latencies had a higher probability of hearing preservation in comparison to those with abnormal preoperative BAER morphology.

The facial nerve in medial acoustic neuromas

2002 ◽  
Vol 97 (5) ◽  
pp. 1083-1090 ◽  
Author(s):  
Christian Strauss
Keyword(s):  
Facial Nerve ◽  
Preoperative Evaluation ◽  
Internal Auditory Canal ◽  
Functional Results ◽  
Consecutive Series ◽  
Nerve Function ◽  
Facial Nerve Function ◽  
Content Type ◽  
Acoustic Neuromas ◽  
Fine Print

Object. Functional results after surgery for acoustic neuromas that have little or no growth within the internal auditory canal are controversial, because these medial tumors can grow to a considerable size within the cerebellopontine angle (CPA) before symptoms occur. Methods. A prospective study was designed to evaluate the surgical implications of the course of the facial nerve within the CPA on medial acoustic neuromas. This study included a consecutive series of 22 patients with medial acoustic neuromas (mean size 32 mm, range 17–52 mm) who underwent surgery via a suboccipitolateral approach between 1997 and 2001. All patients underwent pre- and postoperative magnetic resonance imaging and preoperative electromyography (EMG). Evaluation was based on continuous intraoperative EMG monitoring and video recordings of the procedure. All patients were reevaluated at a mean of 19 months (6–50 months) postsurgery. Preoperative evaluation of facial nerve function revealed House—Brackmann Grade I in six, Grade II in 14, and Grade III in two patients. During surgery a distinct splitting of the nerve at the root exit zone through its intracisternal course was seen in eight patients and documented by selective electrical stimulation. The facial nerve was separated into a smaller portion that ran cranially and parallel to the trigeminal nerve, and a larger portion on the anterior tumor surface. Both components joined anterior to the porus without major spreading of the nerve bundle. In two cases the nerve was found on the posterior surface of the cranial tumor. In one case the facial nerve entered the porus of the canal at its lower part, obtaining the expected anatomical position proximally within the middle portion of the canal. An anterior cranial, middle (five cases each), or caudal course (two cases) was seen in the remaining patients. After surgery, facial nerve function deteriorated in most cases; on follow-up evaluation House—Brackmann Grade I was found in 11, Grades II and III in 10, and Grade V in one patient. Conclusions. The facial nerve requires special attention in surgery for medial acoustic neuromas, because an atypical course of the nerve can be expected in the majority of cases. A split course of the nerve was found in 36% of the cases presented. Meticulous use of intraoperative facial nerve stimulation and continuous monitoring ensures facial nerve integrity and offers good functional results in patients with medial acoustic neuromas.

Stereotactic radiotherapy for the treatment of acoustic neuromas

2004 ◽  
Vol 101 (Supplement3) ◽  
pp. 362-372 ◽  
Author(s):  
Michael T. Selch ◽  
Alessandro Pedroso ◽  
Steve P. Lee ◽  
Timothy D. Solberg ◽  
Nzhde Agazaryan ◽  
...  
Keyword(s):  
Stereotactic Radiotherapy ◽  
Tumor Size ◽  
Cranial Nerve ◽  
Target Volume ◽  
Tumor Control ◽  
Content Type ◽  
Seventh Cranial Nerve ◽  
Acoustic Neuromas ◽  
Fine Print

Object. The authors sought to assess the safety and efficacy of stereotactic radiotherapy when using a linear accelerator equipped with a micromultileaf collimator for the treatment of patients with acoustic neuromas. Methods. Fifty patients harboring acoustic neuromas were treated with stereotactic radiotherapy between September 1997 and June 2003. Two patients were lost to follow-up review. Patient age ranged from 20 to 76 years (median 59 years), and none had neurofibromatosis. Forty-two patients had useful hearing prior to stereotactic radiotherapy. The fifth and seventh cranial nerve functions were normal in 44 and 46 patients, respectively. Tumor volume ranged from 0.3 to 19.25 ml (median 2.51 ml). The largest tumor dimension varied from 0.6 to 4 cm (median 2.2 cm). Treatment planning in all patients included computerized tomography and magnetic resonance image fusion and beam shaping by using a micromultileaf collimator. The planning target volume included the contrast-enhancing tumor mass and a margin of normal tissue varying from 1 to 3 mm (median 2 mm). All tumors were treated with 6-MV photons and received 54 Gy prescribed at the 90% isodose line encompassing the planning target volume. A sustained increase greater than 2 mm in any tumor dimension was defined as local relapse. The follow-up duration varied from 6 to 74 months (median 36 months). The local tumor control rate in the 48 patients available for follow up was 100%. Central tumor hypodensity occurred in 32 patients (67%) at a median of 6 months following stereotactic radiotherapy. In 12 patients (25%), tumor size increased 1 to 2 mm at a median of 6 months following stereotactic radiotherapy. Increased tumor size in six of these patients was transient. In 13 patients (27%), tumor size decreased 1 to 14 mm at a median of 6 months after treatment. Useful hearing was preserved in 39 patients (93%). New facial numbness occurred in one patient (2.2%) with normal fifth cranial nerve function prior to stereotactic radiotherapy. New facial palsy occurred in one patient (2.1%) with normal seventh cranial nerve function prior to treatment. No patient's pretreatment dysfunction of the fifth or seventh cranial nerve worsened after stereotactic radiotherapy. Tinnitus improved in six patients and worsened in two. Conclusions. Stereotactic radiotherapy using field shaping for the treatment of acoustic neuromas achieves high rates of tumor control and preservation of useful hearing. The technique produces low rates of damage to the fifth and seventh cranial nerves. Long-term follow-up studies are necessary to confirm these findings.

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.

Enhanced Retrosigmoid Exposure with Posterior Semicircular Canal Resection

1996 ◽  
Vol 115 (1) ◽  
pp. 46-48 ◽  
Author(s):  
Ltc Moises Arriaga ◽  
Maj Michael Gorum
Keyword(s):  
Semicircular Canal ◽  
Cerebellopontine Angle ◽  
Internal Auditory Canal ◽  
Hearing Preservation ◽  
Middle Fossa ◽  
Posterior Semicircular Canal ◽  
Acoustic Neuromas

A subset of patients with acoustic neuromas and useful hearing have tumors that are inadequately approached by both middle fossa and retrosigmoid techniques. The enhanced retrosigmoid technique combines the hearing preservation of posterior semicircular canal ablation to achieve lateral internal auditory canal exposure with the ample cerebellopontine angle exposure of the standard retrosigmoid technique.

Preservation of hearing in patients undergoing microsurgery for vestibular schwannoma: degree of meatal filling

2005 ◽  
Vol 102 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Gérard Mohr ◽  
Burak Sade ◽  
Jean-Jacques Dufour ◽  
Jamie M. Rappaport
Keyword(s):  
Vestibular Schwannoma ◽  
Tumor Size ◽  
Intraoperative Monitoring ◽  
Statistical Significance ◽  
Multivariable Analysis ◽  
Internal Auditory Canal ◽  
Magnetic Resonance Images ◽  
Content Type ◽  
Incomplete Filling ◽  
Fine Print

Object. Preservation of hearing has become a standard goal in selected patients undergoing surgery for a vestibular schwannoma (VS). This study was aimed at analyzing the role played by filling of the internal auditory canal (IAC) as well as those played by preoperative hearing quality, and tumor size in the postoperative preservation of serviceable hearing (SH). Methods. Three hundred eighty-six patients with VS were treated. Hearing preservation was attempted in 128 cases (33.2%) by using intraoperative monitoring and following a retrosigmoid approach. The maximal extrameatal size of the tumor, its extension within the IAC, and pre- and postoperative hearing quality, according to the Gardner—Robertson classification, were evaluated. Preservation of SH was achieved in 24.2% of the 128 patients. With respect to tumor size, SH was preserved in 39% of 77 patients harboring a tumor 15 mm wide or smaller and in 2% of 51 patients with lesions 16 mm wide or larger (p < 0.001). With regard to filling of the IAC, among 63 patients harboring a tumor 15 mm or smaller, in whom magnetic resonance images were available, SH was preserved in 52.8% of 36 patients with partial filling and in 25.9% of 27 patients with complete filling (p = 0.032). Concerning preoperative hearing quality, in the patients with tumors 15 mm or smaller, SH was preserved in 46.5% of 43 patients with Gardner—Robertson Class I hearing and 29.4% of 34 patients with Class II hearing (p = 0.126). Both tumor size and the extent of IAC filling proved statistically significant in a multivariable analysis (p < 0.001 and p = 0.026, respectively). Conclusions. Incomplete filling of the IAC and a tumor size of 15 mm or smaller are independent favorable factors in SH preservation. Excellent preoperative hearing appears to have a positive impact but does not have statistical significance. Intraoperative monitoring is useful in guiding the dissection; however, the surgeon's knowledge of topographical landmarks and meticulous surgical technique remain the essential factors of success.

Hearing preservation in medial vestibular schwannomas

2008 ◽  
Vol 109 (1) ◽  
pp. 70-76 ◽  
Author(s):  
Christian Strauss ◽  
Barbara Bischoff ◽  
Johann Romstöck ◽  
Jens Rachinger ◽  
Stefan Rampp ◽  
...  
Keyword(s):  
Growth Pattern ◽  
Auditory Evoked Potentials ◽  
Internal Auditory Canal ◽  
Hearing Preservation ◽  
Neck Surgery ◽  
Underlying Disease ◽  
Cochlear Nerve ◽  
Vestibular Schwannomas ◽  
Consecutive Series ◽  
Tumor Removal

Object Vestibular schwannomas (VSs) with no or little extension into the internal auditory canal have been addressed as a clinical subentity carrying a poor prognosis regarding hearing preservation, which is attributed to the initially asymptomatic intracisternal growth pattern. The goal in this study was to assess hearing preservation in patients who underwent surgery for medial VSs. Methods A consecutive series of 31 cases in 30 patients with medial VSs (mean size 31 mm) who underwent surgery between 1997 and 2005 via a suboccipitolateral route was evaluated with respect to pre- and postoperative cochlear nerve function, extent of tumor removal, and radiological findings. Intraoperative monitoring of brainstem auditory evoked potentials was performed in all patients with hearing. Patients were reevaluated at a mean of 30 months following surgery. Results Preoperative hearing function revealed American Academy of Otolaryngology–Head and Neck Surgery Foundation Classes A and B in 7 patients each, Class C in 4, and D in 9. Four patients presented with deafness. Hearing preservation was achieved in 10 patients (Classes A–C in 2 patients each, and Class D in 4 patients). Tumor removal was complete in all patients with hearing preservation, except for 2 patients with neurofibromatosis. In 4 patients a planned subtotal excision was performed due to the individual's age or underlying disease. In 1 patient a recurrent tumor was completely removed 3 years after the initial procedure. Conclusions The cochlear nerve in medial VSs requires special attention due to the atypical intracisternal growth pattern. Even in large tumors, hearing could be preserved in 37% of cases, since the cochlear nerve in medial schwannomas may not exhibit the adherence to the tumor capsule seen in tumors with comparable size involving the internal auditory canal.

Vasoactive treatment for hearing preservation in acoustic neuroma surgery

2001 ◽  
Vol 95 (5) ◽  
pp. 771-777 ◽  
Author(s):  
Christian Strauss ◽  
Barbara Bischoff ◽  
Mandana Neu ◽  
Michael Berg ◽  
Rudolf Fahlbusch ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Acoustic Neuroma ◽  
Auditory Evoked Potentials ◽  
Consecutive Series ◽  
Hearing Level ◽  
Pathophysiological Mechanism ◽  
Content Type ◽  
Acoustic Neuromas ◽  
Vasoactive Medication ◽  
Fine Print

Object. Delayed hearing loss following surgery for acoustic neuroma indicates anatomical and functional preservation of the cochlear nerve and implies that a pathophysiological mechanism is initiated during surgery and continues thereafter. Intraoperative brainstem auditory evoked potentials (BAEPs) typically demonstrate gradual reversible loss of components in these patients. Methods. Based on this BAEP pattern, a consecutive series of 41 patients with unilateral acoustic neuromas was recruited into a prospective randomized study to investigate hearing outcomes following the natural postoperative course and recuperation after vasoactive medication. Both groups were comparable in patient age, tumor size, and preoperative hearing level. Twenty patients did not receive postoperative medical treatment. In 70% of these patients anacusis was documented and in 30% hearing was preserved. Twenty-one patients were treated with hydroxyethyl starch and nimodipine for an average of 9 days. In 66.6% of these patients hearing was preserved and in 33.3% anacusis occurred. Conclusions. These results are statistically significant (p < 0.05, χ2 = 5.51) and provide evidence that these surgically treated patients suffer from a disturbed microcirculation that causes delayed hearing loss following removal of acoustic neuromas.

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