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At least 901 records · Page 50Linked to original sources
PubMed1993

Preservation of cochlear nerve function in acoustic neurinoma surgery.

A total of 55 cases with unilateral acoustic neurinoma which were operated on by the lateral suboccipital approach was studied to elucidate factors which influence postoperative hearing acuity. We analyzed several factors: preoperative hearing level, tumour size, tumour consistency (cystic or solid), and anatomical location of the cochlear nerve. The size of the tumours ranged from 1.2 to 5.8 cm in diameter. Thirty of 55 cases (55%) preoperatively had remaining cochlear function. The smaller the size of tumour, the higher was the preoperative hearing level excepting those tumours with a diameter of 5 cm or greater, which had relatively good hearing and often contained large cysts. As to the consistency of the tumours, 41 were solid and 14 were cystic, where 19 (46%) and 11 (79%) cases had had preoperative hearing, respectively. Anatomical continuity of the cochlear nerve was maintained at surgery in 15 of 30 cases with preoperatively remaining hearing; cochlear function was preserved after surgery in 9 of the 15 cases. It was located counter-clockwise (caudally) to the facial nerve at an angle of 50 degrees on average when they were projected on the right side. The distance or interrelation between the two nerves had no bearing on postoperative hearing preservation. Postoperatively, hearing acuity was improved in 6 cases (20%) with a mean value of 5.6 dB, unchanged in 3 (10%), and deteriorated in 21 (70%) among the 30 cases with remaining preoperative-hearing. When the tumour was less than 2 cm or cystic, better hearing preservation was expected.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1996

Continuous retrograde monitoring of the facial nerve: preliminary experience during acoustic neuroma surgery.

Continuous electromyographical (EMG) monitoring of the facial nerve is widely used during acoustic tumor surgery. Mechanical stimulation of the facial nerve is capable of eliciting synchronous and asynchronous EMG responses alerting the surgeon to damaging maneuvers performed on the nerve. Mechanical stimulation, however, elicits EMG responses only when the nerve has been injured by the underlying pathology or previous surgical maneuvers, and the technique is sensitive to administration of muscular blockers. In addition, EMG is unable to furnish quantitative information about the damage. The present paper illustrates an alternative technique for intraoperative facial nerve monitoring, that is, the recording of facial nerve antidromic potentials (FNAPs).Eleven subjects operated on by acoustic neuroma surgery via a retrosigmoid approach (tumor sizes ranging from 12 to 28 mm) participated in the investigation. Bipolar electrical stimulation of the marginalis mandibulae was performed to elicit FNAPs. Stimulus intensity ranged from 2 to 6 mA with a delivery rate of 7/second. A silver-wire electrode positioned on the proximal portion of the acoustic-facial bundle was used to record action potentials. Changes in latency and amplitude of FNAPs were analyzed as a function of the main surgical steps. FNAP monitoring provided quantitative real-time information about damaging maneuvers performed on the nerve and allowed prediction of postoperative facial function.

Journal Article↗
PubMed2003

Facial F wave recording: a novel and effective technique for extra- and intraoperative diagnosis of facial nerve function in acoustic tumor disease.

OBJECTIVE: To investigate the diagnostic yield of facial F wave recording in patients with acoustic neurinomas intraoperatively and extraoperatively. Study design and setting Prospective study, comparative evaluation of facial F waves, transcranial magnetic stimulation of the facial motor cortex, blink reflex, and intraoperative online electromyographic activity. The study was performed in the neurosurgical department of a university hospital. RESULTS: Extraoperatively, only F wave latencies were closely correlated to tumor diameter as an independent variable. Intraoperatively, loss of F waves was specific for the development of a severe to total facial paresis postoperatively. A transient loss of F waves heralds an imminent danger of severe facial dysfunction. CONCLUSION: Facial F wave recording provides valuable information on the functional status of the nerve intra- and extraoperatively. SIGNIFICANCE: Facial F wave recording should be used as a standard electrodiagnostic technique in addition to transcranial magnetic stimulation and blink reflex recording. It seems particularly useful for intraoperative facial nerve monitoring.

Electric Stimulation↗
PubMed1991

[Electrophysiologic evaluation of the facial nerve in patients with acoustic neuromas. Preliminary results of a comparative study between conventional electroneurography and transcranial magnetic pulse stimulation].

Subclinical invasion of the facial nerve by acoustic neuromas may be identified preoperatively using conventional electroneurography (ENOG). The clinical application of extratemporal stimulation distal to the stylomastoid foramen is limited in these cases because of the more proximal site of the lesion. Transcranial magnetic coil stimulation (MCS) is a non-invasive means by which the facial nerve is stimulated at the level of the motor cortex or the brain stem before it enters the internal auditory canal. Topographically such an assessment may have more diagnostic relevance than other forms of electrical stimulation in acoustic neuroma patients. To test this theory the facial nerves of 20 patients with an acoustic neuroma were stimulated using ENOG and MCS before and 1 week after operation. Stimulation parameters were comparable and included threshold, double-threshold and supra-threshold levels of stimulation while compound action potential amplitudes and early and late response latencies were monitored. All the patients had clinically normal facial nerve function preoperatively. Using ENOG 65% of the patients showed amplitude reduction on the tumour side, whereas 70% of these patients had a reduction of amplitude to MCS. Combining both techniques, 88% of the patients had a significant amplitude reduction on the neuroma side. Comparison of the preoperative threshold measurements of both techniques showed that there was a significantly higher incidence of detection of lesions on the diseased side in neuromas larger than 2 cm by the use of MCS.

Dominance, Cerebral↗
PubMedDate not supplied

Analysis of the prognosis and the recovery process of profound facial nerve paralysis secondary to acoustic neuroma resection.

The prognosis and the recovery process of facial nerve paralysis were reviewed in 74 patients who, despite preservation of nerve continuity, showed no facial movement after acoustic neuroma resection. In 50 or 67.6% of patients, facial movement recovered sufficiently so as not to require any reanimation procedures. However, no apparent sign of remission was observed for 7-49 months in the other 24 patients (32.4%), and hypoglossal-facial nerve anastomosis was performed in 20 of these patients. When remission was seen, the first sign of muscle movement appeared most frequently after 3-4 months but, in a small number of patients, it was also seen within 1.5 months or after 5-10 months. Based upon these results, the timing of reanimation procedures for facial nerve paralysis following acoustic neuroma resection is discussed.

Adult↗
PubMed1991

[Transcranial magnetic stimulation of the facial nerve in patients with acoustic neuroma].

Magnetic stimulation of the human facial nerve was used in 30 patients with small or medium-sized acoustic neurinomas pre-operatively. Needle-EMG revealed symmetrical aspect in the orbicularis oris muscle on the affected and on the contralateral side. The latencies in the extracranial part of the facial nerve after supramaximal electric stimulation in the area of the stylomastoid foramen and the latencies after temporo-occipital, transcranial magnetic stimulation were measured. A comparison of the data showed a significant increase in the temporal conduction time (difference between latencies after transcranial magnetic stimulation and electrical mastoid stimulation) between the healthy and the affected side in most cases. This study revealed tendencies between prolongation of the latencies and the tumour size. No correlations were obtained to audiological or intra-operative findings.

Adult↗
PubMed1991

Intraoperative facial nerve monitoring: prognostic aspects during acoustic tumor removal.

Intraoperative facial nerve monitoring with electrical stimulation (IFNMES) has become an integral part of acoustic tumor surgery. We reviewed the records of fifty-six patients who underwent translabyrinthine acoustic tumor removal with IFNMES. There was excellent correlation between intraoperative facial nerve activity and immediate postoperative facial nerve function (24 hours after surgery and at hospital discharge). Our data would suggest that patients who exhibit less than 500 microvolts of ongoing EMG activity during surgery, and who yield at least a 500-microvolt contraction when stimulated with 0.05 milliamps at the brainstem after tumor removal, can expect an excellent immediate facial nerve result (grade I or II).

Ear Neoplasms↗
PubMed1991

[Peroperative monitoring of the facial nerve in surgery for acoustic neuroma].

This paper reports our experience about intraoperative facial nerve monitoring carried out in 97 patients operated on by a retrosigmoid approach. Intra-operative facial nerve monitoring was performed using a pneumatic sensor which transforms into acoustic signals contractions of facial muscles elicited by mechanical, electrical or thermal stimulations of facial nerve. Long term results showed that a normal facial function (grade I) was achieved in 90.5% of patients, 4 patients were grade II, 2 patients grade III, a total paralysis (grades V and VI) was persistent in 3 patients. Our experience with facial nerve monitoring suggests a modification of the strategy of dissection based upon a preservation of the arachnoid veil and a medial to lateral direction of dissection.

Electric Stimulation↗
PubMedDate not supplied

Long-term prognosis of profound facial nerve paralysis secondary to acoustic neuroma resection.

The long-term prognosis of profound facial nerve paralysis was reviewed in 107 patients who, despite preserved nerve continuity, showed no facial movement after acoustic neuroma resection. Spontaneous recovery occurred in 77 patients. However, there was no apparent recovery in 30 patients. Twenty-two of these patients underwent hypoglossal-facial nerve anastomosis 7-33 months after tumor resection. When spontaneous recovery occurred, the first sign of remission was observed between 3 and 4 months after surgery in nearly half of the patients. Such a sign did not appear after 12 months. The recovery of facial movement deteriorated depending on how long remission onset was delayed. However, the quality of facial movement in patients with such delayed remission was still identical or better than that in those after hypoglossal-facial nerve anastomosis. These results showed that hypoglossal-facial nerve anastomosis should be performed approximately 1 year after tumor resection if no sign of remission has been observed by then.

Anastomosis, Surgical↗
PubMedDate not supplied

MR of acoustic neuromas--relationship to cranial nerves.

In this report, the relationship of acoustic neuromas to the adjacent cranial nerves is discussed. On T1-weighted images, the trigeminal nerve was detected in all 13 cases. Mild to marked compression of these nerves by the tumors was observed in eight cases. The extent of compression did not always correspond to the clinical symptoms. In four cases with a maximum tumor diameter of 2 cm or less, the 7th and 8th cranial nerves were identified. There was no facial palsy in these patients. Two patients with a tumor diameter of more than 2 cm also had no facial palsy. All patients, including those with small tumors, complained of hearing loss and/or tinnitus. While MR imaging has some limitations, it is an effective imaging modality for showing the relationship between tumors and nerves.

Adult↗
PubMed1993

Intraoperative facial nerve monitoring in posterior fossa acoustic neuroma surgery.

Intraoperative facial nerve monitoring has become an indispensable tool during cerebellopontine angle surgery. Ninety-seven patients underwent surgical removal of an acoustic neurinoma with the use of a pneumatic sensor monitoring between January 1, 1986, and December 31, 1990. In the early postoperative period, a normal or near-normal facial function (grades I and II) was achieved in 86% of the patients, a moderate dysfunction (grade III) was present in 7%, and a total or severe dysfunction (grades V or VI) was present in 6%. Normal function at 1 year was achieved in 90.5% of the patients, 4% were grade II, a moderate dysfunction (grade III) was present in 2%, and 3% showed a total or severe dysfunction (grade V and VI). The incidence of normal function decreased with tumor size, with an occurrence rate of 100%, 94%, and 91% in small, medium, and large tumors, respectively. In eight consecutive patients, all responses detected by the monitoring during the operation were collected and analyzed according to intraoperative events. Analysis of the results indicate that 95% of the 316 mechanically induced stimulations were of small or extremely small amplitude, and only 5% were of moderate amplitude. A medial-to-lateral strategy of dissection, preservation of the arachnoid veil over the facial nerve, a control by the monitoring of the amount of traction, and a more widespread use of sharp dissection were the major approaches to reduce surgical trauma during dissection.

Adult↗