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At least 991 records · Page 55Linked to original sources
PubMed1988

Electrophysiological monitoring during acoustic neuroma and other posterior fossa surgery.

Techniques used to monitor the function of the seventh and eighth cranial nerves during acoustic neuroma and other posterior fossa surgery are reviewed. The auditory brainstem response (ABR), electrocochleogram (ECochG) and direct recording from the auditory nerve (CNAP) were compared. The best technique is the ECochG, although in many cases, the CNAP should be used as a back-up technique. The CNAP is especially useful for the identification of the auditory nerve. Both can provide real-time feedback on the physiological integrity of the auditory nerve. The ABR may be helpful in monitoring brainstem function. For some procedures, optimal monitoring requires the combined recording of all three techniques. Monopolar constant-voltage intracranial stimulation of the facial nerve is helpful for the identification and preservation of the facial nerve. Audio monitoring of spontaneous electromyographic activity provides real-time feedback on the effect of surgical manipulation of the nerve. Monitoring of ephaptic transmission in the facial nerve during microvascular decompression for hemifacial spasm aids in the identification of the offending vessel.

Action Potentials↗
PubMed1981

[Vestibular Responses of neurons of the anterior suprasylvian region of the cat cortex and their interaction with responses to acoustic stimulation and stimulation of the facial nerve].

Neuronal responses to stimulation of the vestibular, acoustic and facial nerves were studied in the cat anterior suprasylvian gyrus cortex under chloralose (70 m/kg). The vestibular projection field was found to be adjacent to and partly overlapped with the acoustic and facial projections. The focus of maximum vestibular-evoked activity was located rostrally to the anterior suprasylvian gyrus and was clearly distinct from that evoked by acoustic auditory and facial stimuli. In the focus of maximal activity of the vestibular projection the vestibular afferent input was predominant.

Afferent Pathways↗
PubMed1998

[Taste and lacrimation after acoustic neuroma surgery].

AIM OF THE STUDY: Postoperative sensory component of the facial nerve after acoustic tumor surgery has received little attention in the literature. The object of the present investigation was to review this specific topic analyzing the postoperative frequency of taste and lacrimation (crocodile tears or dry eye) abnormalities. MATERIAL AND METHODS: 54 patients who underwent acoustic tumor removal were selected for this study. Each of these patients was recalled and pre and postoperative evolution of the sensory dysfunction were assessed. The latters were correlated with the facial function evaluated according to the House-Brackmann classification. RESULTS: Postoperative taste dysfunction (reduced or changed sensation) was complained by 38.5% of the patients. After surgery, 42.3% of the cases had crocodile tears, while in 59.6% altered tearing occurred. DISCUSSION: The present study, according to the Irving et al's experience confirmed a significant incidence of postoperative abnormal function of the sensory facial nerve. The influence of the motor component on these outcomes was variable. Lacrimation worsened when facial function was poor. On the other hand, grades V or VI did rarely manifest crocodile tears. Clinically, these findings implies the importance of a preoperative counseling of such particular aspect in the candidates to surgery of acoustic neuroma in order to adequately motivate them and, at the same time, to reduce their psychological discomfort.

Adult↗
PubMed2005

[Function of the facial nerve after operative treatment of acoustic neurinomas. Influence of intraoperative monitoring].

The aim of this study was to evaluate the influence of intraoperative monitoring on the function of the facial nerve after surgical treatment of acoustic neurinomas, classified according to the grading system of Stennert. One hundred thirty patients were divided into two groups. The first group underwent surgery without intraoperative facial monitoring; the second group included intraoperative facial monitoring. Concerning degree of paresis, preoperatively there was no statistically significant difference between the two groups (group 1: 0.77+/-1.5; group 2: 0.4+/-1.2). Despite structural preservation of the facial nerve, postoperative deterioration of its function was observed which consecutively improved postoperatively. Postoperatively, the mean degree of paresis increased to 4.4+/-3.0 in group 1 and 2.4+/-2.3 in group 2. For better understanding of the role of intraoperative monitoring, we investigated the outcome of patients with acoustic neurinomas who underwent surgery over the following 6 months postoperatively. At that time, function improved by 4.1+/-3.2 (group 1) and 2.0+/-2.3 (group 2). We could show that intraoperative monitoring of the facial nerve was a significant factor for better postoperative function in patients undergoing microsurgical excision of neurinomas (P=0.001) .

Facial Nerve↗
PubMed1997

Management of vestibular schwannomas (acoustic neuromas): auditory and facial nerve function after resection of 120 vestibular schwannomas in patients with neurofibromatosis 2.

OBJECTIVE: Vestibular schwannomas (VSs) affect young patients with Neurofibromatosis 2 (NF-2) and cause very serious problems for hearing, facial expression, and brain stem function. Our objective was to determine a therapy concept for the right timing and indication of neurosurgical therapy. METHODS: In 1000 consecutive VS resections, 120 tumors in 82 patients with NF-2 were surgically treated by the same surgeon (MS) at the Department of Neurosurgery at Nordstadt Hospital from 1978 to 1993. The mean age of the patients was 27.5 years. Sixty tumors were surgically treated in 41 male patients, and 60 tumors were surgically treated in 41 female patients. Bilateral tumor resection was performed in 38 patients (76 operations, after previous partial surgery in 15 cases elsewhere), and unilateral operations were performed in 44 patients, 5 of whom had undergone ipsi- or contralateral surgery that was performed elsewhere. The operative and clinical findings are evaluated and compared with the data of patients without NF-2. RESULTS: In 105 cases, complete tumor resections were achieved. In 15 cases, deliberate subtotal resections were performed. These were for brain stem decompression in 4 cases and for hearing preservation in the last hearing ear in 11 cases, with successful preservation in 8 of the 11. Pre- and postoperative hearing rates were higher in male than in female patients (70% in male versus 65% in female patients before surgery and 40.5 versus 31%, respectively, after surgery). Hearing was preserved in 29 of 81 ears (36%). The rate of preservation was 24% in cases of large tumors and 57% in cases of small tumors (<30 mm). Twenty-one of 82 patients (26%) were bilaterally deaf before surgery. Twenty-five patients had uni- or bilateral hearing after surgery (i.e., 41 % of those with preoperative hearing or 30.5% of the whole group). Anatomic facial nerve preservation was achieved in 85%. The facial nerve was reconstructed intracranially at the cerebellopontine angle by sural grafting in 17 cases and by hypoglossal-facial reanimation in 5. Two deaths occurred 1 and 3 months postsurgically as a result of malignant tumor growth with brain stem dysfunction and respiratory problems. In summary, for patients with NF-2, the presentation ages are lower, tumor progression is faster, the chances of anatomic and functional nerve preservation are lower, the chances of good outcomes are best when surgery is performed early and when there is good preoperative hearing function, and the danger of sudden hearing loss is higher. The chances and danger often differ from side to side among individual patients. CONCLUSION: The indication and the timing of tumor resections are in some respects different from normal VS handling and are dependent on the tumor extension and related necessity of brain stem decompression and on the auditory function. As an optimal goal, completeness of resection with functional cochlear nerve preservation is formulated, and as an acceptable compromise, subtotal microsurgical resection with functional cochlear nerve preservation in the last hearing ear is suggested.

Adolescent↗