PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “NERVES, ACOUSTIC”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 865 records · Page 48Linked to original sources
PubMed1984

Facial nerve grafting in acoustic neurinoma.

The introduction of the operating microscope has strongly influenced our surgical possibilities for preserving and reconstructing the facial nerve in tumor surgery in the cerebellopontine angle as well as in the internal auditory canal. In 1975, we introduced a new method for facial nerve reconstruction in the cerebellopontine angle. Since then, we have operated upon 20 patients using this technique of intracranial-intratemporal nerve graft; 15 of these have been done directly after the removal of the acoustic neurinoma. Of these patients, 12 have been followed over a period of 9 to 87 months. A sural nerve graft 4 to 5 cm in length was placed between the central stump of facial nerve at the brain stem and the distal end of facial nerve in tympanal or mastoidal course after total removal of the acoustic neurinoma. The results, demonstrated in this paper, are highly encouraging. It is recommended that this operative technique be included in the entire concept of microsurgery in the cerebellopontine angle.

Adolescent↗
PubMed1991

Preservation of facial nerve function in acoustic neuroma surgery by the extended middle cranial fossa approach.

The anatomical preservation rates of the facial nerve and postoperative facial nerve function were investigated in cases of initial operation for acoustic neuroma by the middle cranial fossa or extended middle cranial fossa approach. The cases were divided chronologically into three groups according to the date of surgery. The rate of anatomical preservation was 93% in the most recent period, compared to 82.4% for the entire series. This was attributable to higher preservation rates being achieved in cases with medium or large tumors with increased experience. Also regarding postoperative facial nerve function, the number of cases with no paralysis or only partial paralysis increased and the number of cases requiring sacrifice of the facial nerve decreased as experience was accumulated in the series. Even when the facial nerve was preserved anatomically, however, facial-hypoglossal anastomosis was carried out actively if facial nerve function did not recover satisfactorily one year after surgery. For this reason, as many as 33% of the patients underwent anastomosis. This high percentage, however, is attributable to anastomosis ultimately being carried out in 47.7% of the patients in the early period; 22.2% of the patients in the most recent period underwent anastomosis.

Adolescent↗
PubMed2006

A novel method in predicting immediate postoperative facial nerve function post acoustic neuroma excision.

UNLABELLED: To determine whether the percentage calculated by dividing the amplitude of postexcision direct facial nerve stimulus responses (at pontomedullary junction) by the amplitude of distal ipsilateral transcutaneous (stylomastoid region) maximal stimulus responses and response amplitude progression by increasing stimulus intensities have predictive value for determining normal or near-normal (House-Brackmann Grade 1 or 2) immediate postoperative facial nerve function. STUDY DESIGN: Intraoperative recordings of three muscle groups: 1) frontalis, 2) orbicularis oculi, and 3) orbicularis oris. Postexcision direct facial nerve stimulation at the pontomedullary junction and transcutaneous maximal facial nerve stimulation at the ipsilateral stylomastoid region and their associated response amplitudes were recorded. SETTING: Tertiary referral center. PATIENTS AND METHODS: Patients who underwent acoustic neuroma surgery from January 2004 to March 2006 with intraoperative facial nerve monitoring and an intact facial nerve after tumor excision were included. Recordings were available for 38 patients. RESULTS: With a stimulus intensity of 0.3 mA at the root exit zone, there was an 81% positive predictive value in patients that exhibited a compound action potential of greater than 20% of maximum (sensitivity, 81%). This increased to 93% when the compound action potential was greater than 50% of maximum. When the amplitude increase was greater than 5 microV, there was a 77% positive predictive value (sensitivity, 87%). CONCLUSION: The percentage of the response amplitude of direct facial nerve stimulation at the pontomedullary junction when compared with the maximum response amplitude of ipsilateral transcutaneous stimulation at the stylomastoid foramen is a good predictor of normal to near-normal immediate postoperative facial nerve function. Progression of amplitude response also seems to be a good predictor of normal to near-normal immediate postoperative facial nerve function.

Adult↗
PubMed1975

Acoustic reflex and reflex decay. Occurrence in patients with cochlear and eighth nerve lesions.

Acoustic reflex and reflex decay tests were administered to 50 normal ears, 50 ears with hearing loss due to noise trauma, 50 ears that had Meniere disease, and 28 ears that had involvement of the eighth nerve. In one normal ear, ten noise trauma ears, 11 Meniere disease ears, and 24 eighth nerve lesion ears to reflexes or reflex decay that were suggestive or retrocochlear lesions were observed. Acoustic reflex and reflex decay results are also compared to tone decay results for these patients.

Acoustic Stimulation↗
PubMed2000

Assessment of facial nerve function in acoustic tumor disease by nasal muscle F waves and transcranial magnetic stimulation.

Standard transcranial magnetic stimulation and nasal muscle F-wave recordings were used to assess proximal facial nerve function in 27 patients with unilateral acoustic tumors (mean diameter, 29 mm) and clinically intact facial nerve function. Latency measurements for F waves and cortical magnetic stimulation were abnormal. Moreover, F ratios, central motor conduction time, and the ratio of response latency to cortical and cisternal magnetic stimulation were significantly increased. Amplitudes were unchanged. Correlation analysis with tumor diameter as dependent variable yielded maximum r values for F-wave latencies (0.57) and F ratios (0.41), whereas for magnetic stimulation, a significant correlation could be found (0.4) only for cortical stimulation. Nasal muscle F-wave recording can reveal clinically inapparent facial nerve dysfunction. Its efficacy in predicting tumor diameter seems to be superior to that of standard magnetic stimulation.

Adult↗
PubMed2002

The facial nerve in medial acoustic neuromas.

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.

Adult↗
PubMed1999

Discriminability of vowel representations in cat auditory-nerve fibers after acoustic trauma.

This paper attempts to connect deficits seen in the neural representation of speech with perceptual deficits. Responses of auditory-nerve fibers were studied in cats exposed to acoustic trauma. Four synthetic steady-state vowels were used as test signals; these stimuli are identical, except that the second format (F2) resonator in the synthesizer was set to 1.4, 1.5, 1.7, or 2 kHz, producing four spectra that differ mainly in the vicinity of the F2 frequency. These stimuli were presented to a large population (523) of auditory-nerve fibers in four cats with sloping high-frequency threshold shifts that reached 50-70 dB at 2-4 kHz. In normal animals, May et al. [Auditory Neurosci 3, 135-162 (1996)] showed previously that the discharge rates of fibers with best frequencies near the F2 frequencies provide enough information to allow discrimination of these stimuli at the performance levels shown by cats in behavioral experiments. Here it is shown that, after acoustic trauma, there is essentially no rate information which would allow the vowels with different F2 frequencies to be discriminated. However, information that could allow discrimination remains in the temporal (phase-locked) aspects of the responses.

Animals↗
PubMed1998

[Postoperative vestibular compensation and facial nerve function after acoustic neuroma operation. Relation to origin of the tumors].

Within the battery of functional tests used in patients considered to have an acoustic neuroma, the use of vestibular examination has been reduced by the widespread use of magnetic resonance imaging. Especially small tumors often show normal or atypical results in electronystagmographic examinations (ENG). The purpose of the present study was to determine the diagnostic value of preoperative vestibular diagnosis in predicting the origin of an acoustic neuroma, as well as the duration of postoperative vestibular compensation and facial nerve function. Sixty-seven patients with intraoperatively confirmed tumor origins were examined preoperatively by ENG and electroneurography in addition to careful clinical examination. Group 1 (n = 45) consisted of patients with tumor originating from the inferior vestibular nerve and group 2 (n = 22) had tumor involving the superior vestibular nerve. Postoperatively, facial nerve function was determined by using the House grading system and vestibular function was defined by ENG 3, 6 and 12 months after surgery. Forty-seven percent of the patients in group 1 showed a pathologic caloric response compared to 64% in group 2. When patients had only a small tumor (< 1 cm), 27% of the patients in group 1 and 71% in group 2 had abnormal caloric results. Vestibular recovery was prolonged in group 1, but a statistically significant difference in postoperative facial nerve function could not be found. These findings confirm that especially small tumors arising from the inferior vestibular nerve can remain undetected by using ENG for diagnosis.

Electronystagmography↗
PubMed1997

Intraoperative monitoring of facial nerve antidromic potentials during acoustic neuroma surgery.

The present paper presents monopolar recording of facial nerve antidromic potentials as an alternative technique to facial electromyography for the continuous monitoring of the facial nerve during acoustic neuroma surgery. The investigation involved 22 patients undergoing acoustic neuroma surgery via a retrosigmoid approach (tumour sizes ranging from 5 to 28 mm). Bipolar electrical stimulation of the marginalis mandibulae was performed to elicit facial nerve antidromic potentials. Stimulus intensity ranged from 2 to 6 mA with a delivery rate of 7/sec. A silver wire monopolar electrode positioned intracranially on the proximal portion of the acoustic facial bundle was used to record antidromic potentials. To define the specific origin of the action potentials and acquire normative data, monopolar and bipolar recordings of facial nerve antidromic potentials were performed in 15 subjects undergoing retrosigmoid vestibular neurectomy for Meniere's disease. The average facial nerve antidromic potential latency was 4.2 (+/- 0.6) msec in subjects with acoustic neuroma and 3.3 (+/- 0.2) msec in subjects with Meniere's disease. Facial nerve antidromic potentials furnished near real-time information about intraoperative facial nerve damage and postoperative facial nerve function during acoustic neuroma surgery. Facial nerve antidromic potentials may provide additional information to conventional EMG. They allow the use of endplate blockers, yield quantitative estimation of facial nerve conduction properties in terms of amplitude and latency, and allow actual continuous monitoring of the facial nerve.

Adult↗
PubMed1994

Interface between the facial nerve and large acoustic neurinomas. Immunohistochemical study of the cleavage plane in NF2 and non-NF2 cases.

In acoustic neurinoma surgery, the surgeon is required to find a cleavage plane between the facial nerve and the tumor, and with the aid of the operating microscope this is usually achieved by fine dissection. A histological specimen of the nerve-tumor interface is available only if the facial nerve was hopelessly adherent to the tumor (usually a large or giant neoplasm) and the surgeon decided to sever the nerve to obtain a complete removal. The authors have examined immunohistochemically the nerve-tumor interface of 20 such facial nerves (six cases of neurofibromatosis 2 (NF2) and 14 of non-NF2) in a series of 351 acoustic neurinomas. The largest extrameatal dimension of the 20 tumors ranged from 20 to 51 mm (median 39 mm). In all of these 20 instances the nerve-tumor contact area was at least partially devoid of a clear-cut histological cleavage plane. Where the facial nerve trunk was attached to the surface of the tumor, nerve fibers of the contact areas either abutted directly against tumor cells or nerve fibers were seen to penetrate into the tumor tissue. Frank embedding of nerve fibers was more frequent in NF2.

Adult↗
PubMed2000

Hypoglossal-facial nerve anastomosis: assessment of clinical results and patient benefit for facial nerve palsy following acoustic neuroma excision.

Despite advances in neuro-otological techniques permanent complete facial palsy may still occur in up to 10% of patients undergoing removal of cerebellopontine angle tumours. Hypoglossal-facial nerve anastomosis is the procedure of choice in our unit for facial reanimation in such patients and below we report the results of hypoglossal-facial nerve anastomosis performed on 29 patients. Assessment of patient benefit from hypoglossal-facial nerve anastomosis was obtained using a questionnaire based on the Glasgow Benefit Inventory. The results showed all patients to have an improvement in their House Brackmann grade following hypoglossal-facial anastomosis with 65% achieving grade III or better. Of the 20 patients who completed the questionnaire, 18 showed a positive benefit (median score 59.5, range 40-77). There was a significant correlation (P < 0.045) between the Glasgow benefit inventory score and House Brackmann grade. Outcome was not affected by the time interval between the acoustic neuroma surgery and performing the hypoglossal-facial nerve anastomosis, sex or length of follow-up. However the Glasgow benefit score was significantly influenced by age (P = 0.023) with younger patients showing more benefit independent of improvement in facial nerve function.

Adolescent↗
PubMedDate not supplied

Electromyographic analysis of profound facial nerve paralysis following acoustic neuroma resection.

The aim of our retrospective study was to determine whether electromyographic findings (motor unit action potentials, MUAPs) can be used in long-term prognosis for profound facial nerve paralysis in patients whose nerve continuity is preserved during surgery for acoustic neuroma. The orbicularis oris, frontal, and orbicularis oculi muscles were examined for the occurrence of MUAPs in 48 such patients. In 30 patients who recovered from complete paralysis within 10 months after surgery, MUAPs in the first two muscles tended to precede the first sign of facial movement. MUAPs appeared in the orbicularis muscle in 80% of these patients at 1 month and in all at 5 months. In the frontal and orbicularis oculi muscles, MUAPs occurred in only 0-20% of these patients in the first month; within 3-5 months the number increased rapidly, and MUAPs were present in 95% of these patients at 10 months. In the remaining 18 patients with long-term complete paralysis (at least 1 year), MUAPs appeared solely in the orbicularis oris muscle: in 20% of these patients in the first month after surgery. While this number slowly rose, there was no period of rapid increase later. We conclude that the occurrence of MUAPs in the orbicularis oris and frontal muscles within 3 months of surgery indicates a good prognosis for reversal of facial nerve paralysis.

Anastomosis, Surgical↗