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PubMedDate not supplied

Classic hypoglossal-facial nerve anastomosis after acoustic neuroma resection. A review of 46 cases.

To clarify the factors contributing to patient satisfaction with facial movement after the classic hypoglossal-facial nerve anastomosis, we examined 46 such patients who consented to an interview and video-recording. No correlation was seen between the physician's evaluation of returned function (according to Yanagihara's 40-point scale and the grading system of House-Brackmann) and the scores (full marks: 100 points) the patients assigned to their own facial movements. Instead the scores that the patients assigned were closely related to subjective oral dysfunction, such as difficulty in masticating, articulating, and swallowing. Those scores did not correlate with eye-related functional deficits. These findings indicate that modified techniques to minimize the hypoglossal nerve deficit may enhance patient satisfaction without sacrificing recovery of facial movements.

Adult↗
PubMed2003

Early rehabilitation of facial nerve deficit after acoustic neuroma surgery.

OBJECTIVE: To determine whether an early physical rehabilitative program could improve and/or accelerate recovery from a postoperative deficit of facial nerve (FN) function. MATERIAL AND METHODS: A retrospective study of the charts of patients who presented a postoperative FN deficit after surgery for acoustic neuroma (AN) was carried out. Twenty-nine patients were enrolled and divided into 2 groups: 18 who underwent early physical rehabilitation and 11 who did not undergo rehabilitation. All the AN patients underwent translabyrinthine removal and were classified preoperatively according to the House-Brackmann staging system. Physical rehabilitation was performed according to Kabat (i.e. neuromuscular facilitation). FN function was assessed postoperatively and classified according to the House-Brackmann grading system. RESULTS: In Grade IV and V patients, early rehabilitation allowed a faster and better recovery with respect to AN patients for whom rehabilitation was not carried out. CONCLUSION: Early physical rehabilitation has proved to be effective as a helpful tool for recovery from FN deficit and it is therefore advisable to use it soon after surgery, especially for FN deficits worse than Grade IV.

Adult↗
PubMed1983

Latency of the acoustic reflex in eighth-nerve tumor.

We evaluated acoustic reflex morphologic features in four subjects with confirmed, unilateral acoustic neuroma. All four subjects showed marked reduction in absolute reflex amplitude and alteration in the reflex amplitude-intensity function in the ear with the eighth-nerve disorder. The early, fast-rising component of the normal reflex was also typically absent in the ears with tumor. Interaural latency comparisons were made in three ways. At equal reflex sensation levels and equal reflex sound pressure levels, latency ws substantially delayed in the ear with the eighth-nerve disorder. At equivalent reflex amplitudes, however, latency was equivalent in normal ears and ears with eighth-nerve disorder. Results suggest that delayed onset of the acoustic reflex in subjects with eighth-nerve disorder may reflect amplitude and wave-form morphologic effects rather than a latency prolongation per se.

Adult↗
PubMed1989

Role of post-operative electroneuronography in predicting facial nerve recovery after acoustic neuroma removal: a pilot study.

Complete clinical facial paralysis immediately after acoustic neuroma removal occurs in between 40 to 90 per cent of patients despite the fact that the facial nerve has been preserved anatomically. Some of these patients improve rapidly with adequate cosmetic and functional recovery. Others however, have incomplete or no return of useful function. A pilot study to assess the prognostic value of electroneuronography (ENOG) in 14 patients following acoustic neuroma removal was performed. The results suggest that post operative ENOG is of value in dividing those patients with anatomically intact facial nerves yet complete clinical paralysis post-operatively into groups: one with rapid improvement to an acceptable functional and cosmetic result and one with prolonged paralysis with incomplete or no recovery. Electroneuronography may thus be used to predict the initial recovery profile in patients with complete facial paralysis after surgery.

Adult↗
PubMed2006

Electrical excitation of the acoustically sensitive auditory nerve: single-fiber responses to electric pulse trains.

Nearly all studies on auditory-nerve responses to electric stimuli have been conducted using chemically deafened animals so as to more realistically model the implanted human ear that has typically been profoundly deaf. However, clinical criteria for implantation have recently been relaxed. Ears with "residual" acoustic sensitivity are now being implanted, calling for the systematic evaluation of auditory-nerve responses to electric stimuli as well as combined electric and acoustic stimuli in acoustically sensitive ears. This article presents a systematic investigation of single-fiber responses to electric stimuli in acoustically sensitive ears. Responses to 250 pulse/s electric pulse trains were collected from 18 cats. Properties such as threshold, dynamic range, and jitter were found to differ from those of deaf ears. Other types of fiber activity observed in acoustically sensitive ears (i.e., spontaneous activity and electrophonic responses) were found to alter the temporal coding of electric stimuli. The electrophonic response, which was shown to greatly change the information encoded by spike intervals, also exhibited fast adaptation relative to that observed in the "direct" response to electric stimuli. More complex responses, such as "buildup" (increased responsiveness to successive pulses) and "bursting" (alternating periods of responsiveness and unresponsiveness) were observed. Our findings suggest that bursting is a response unique to sustained electric stimulation in ears with functional hair cells.

Animals↗
PubMed1994

Facial nerve outcome in acoustic tumor surgery.

Seventy-three procedures involving 70 acoustic tumors were carried out over 3 years. The majority of tumors (65) were removed by the translabyrinthine approach. Tumor size ranged from 0.5 through 5.0 cm. All patients underwent intraoperative facial nerve monitoring: 22 patients developed immediate facial palsy (House-Brackmann grades II-VI); 11 patients recovered completely; 11 patients (15.7%) had persistent paralysis. The incidence of long-term, poor outcome (H-B grade IV-VI) was 5.7 percent. The overall incidence of facial palsy was not found to be related to tumor size; however, facial paralysis associated with large tumors exhibited a poorer House-Brackmann grade compared to small and medium lesions. The use of intraoperative facial monitoring has enhanced the surgeon's ability to preserve facial nerve function by reducing the overall incidence of postoperative facial paralysis.

Cranial Nerve Neoplasms↗
PubMed2000

Morphological evidence that impaired intraneural microcirculation is a possible mechanism of eighth nerve conduction block in acoustic neuromas.

In an attempt to better understand the mechanism of eighth nerve dysfunction in acoustic neuromas (vestibular schwannomas), we have morphologically examined microvessels and nerve fibers in the intracanalicular portion of eighth nerve specimens attached to these tumors. At the light microscopic level, microvessels were well preserved in all the specimens, even in the extremely flattened or markedly small nerve fascicles. However, the density of microvessels was quite variable in the different specimens, presumably as the result of different levels of compression by the tumors and the subsequent formation of a collateral microcirculation in each nerve. Focal areas of mild endoneurial fibrosis were found in 9 out of 22 specimens examined, but severe and widespread degeneration or demyelination was not found in any of the specimens. Ultrastructural studies frequently revealed mild to moderate abnormalities in myelin sheaths, and occasionally showed endothelial hyperplasia and hypertrophy in all the specimens. These findings are consistent with the slight to moderate reduction of endoneurial blood flow in the eighth nerves. The resultant ischemic condition in the eighth nerve may account for the eighth nerve conduction block in acoustic neuromas.

Adult↗
PubMed1989

Facial nerve recovery following acoustic neuroma surgery.

A series of 76 consecutive patients undergoing unilateral acoustic neuroma excision is reported. Preoperative facial weaknesses and a tumour larger than 2.5 cm were predictive factors of poor facial nerve recovery, re-emphasising the need to detect and remove these tumours at an early stage. Electroneuronography performed around one week after surgery appears to be a good indicator of the likelihood of recovery in facial nerves which are anatomically intact, but which show no function at that stage. Multiple rehabilitative procedures are often required when inadequate function or poor cosmetic results are obtained. Primary nerve repair or facial-hypoglossal anastomosis provide better rehabilitative results than dynamic and static procedures.

Adolescent↗
PubMed1992

Facial nerve outcome in acoustic neuroma surgery.

Patients consider facial paralysis the most concerning sequelae following acoustic tumor resection. Surgical and anesthetic refinements have lowered operative mortality to allow the surgeon to focus on preserving facial nerve function. Tumor size, microsurgical technique, and intraoperative monitoring are the most important factors that define the risk of postoperative facial paralysis. A protocol for uniform surgical reporting is proposed.

Facial Nerve↗
PubMed1994

Preservation of facial, cochlear, and other nerve functions in acoustic neuroma treatment.

Between March 1966 and September 1992, 1400 acoustic neuromas were treated in Paris, France, by surgical excision. The findings over the last 7 years are presented. The translabyrinthine approach has been used in more than 85% of cases. Where hearing preservation is attempted, the middle fossa approach has been adapted for intracanilicular tumors and the retrosigmoid approach for small tumors extending into the cerebellopontine angle, in which the fundus of the internal meatus is free of tumor. The main goal is to achieve a grade I or II result in facial function within 1 month of surgery. Results improved during 1991 after the introduction of continuous facial nerve monitoring and the use of the Beaver mini-blade for dissection of tumor from nerve. With these techniques, facial function of grade I or II at 1 month improved from 20% to 52% for large tumors (larger than 3 cm), from 42% to 81% for medium tumors (2 to 3 cm). and from 70% to 92% for small tumors (up to and including 2 cm extracanalicular). The facial nerve was at greater risk using the retrosigmoid or middle fossa approaches than by the translabyrinthine route. Since 1985, success in hearing preservation has changed little, with useful hearing being preserved in 38.2% of cases operated on by means of the retrosigmoid route and a 36.4% of cases after the middle fossa approach. In older patients with good hearing and small tumors, observation with periodic MRI scanning is recommended. Despite earlier diagnosis, the number of patients suitable for hearing preservation surgery remains very limited and careful selection is required. Trigeminal nerve signs were present in 20% of cases preoperatively, in 10% postoperatively, and recovered spontaneously. Palsies of the other cranial nerves after surgery were much rarer and were as follows: sixth nerve (abducens), 0.5%; ninth nerve (glossopharyngeal), 1.4%; and tenth nerve (vagus), 0.7%. The importance of preservation of function of the nervus intermedius of Wrisberg is stressed. These results emphasize the advantages of the translabyrinthine approach, offering greater security to the facial nerve and lower morbidity.

Adolescent↗
PubMed1983

Acoustically derived auditory nerve action potential evoked by electrical stimulation: an estimation of the waveform of single unit contribution.

An experimental study of the electrical stimulation of the guinea pig cochlea is made using an electrode on the round window for both stimulation and recording. The neural response is separated from the electrical artifact with a masking procedure combined with a low amplification, "statistical" averaging method [Charlet de Sauvage et al., Hear. Res. 2, 343-346 (1980)]. The high electrical impedance required for recording physiological responses implies the use of a current pulse generator. Monitoring of evoked potentials from the auditory cortex provides evidence that the effects of electrical stimulation (and of masking noise) are of auditory origin. The electrically evoked round window response is of very short latency (less than 0.2 ms). There is a response threshold for both electrical stimulus and masking noise. The response amplitude varies monotonically as a function of masking noise or electrical stimulus intensity. Experiments with high-pass noise masking suggest that the electrical stimulus is mainly acting on basal fibers. The response latency and waveform are independent of electrical stimulus intensity, repetition rate, masker level, or spectrum. Little intersubject variation is noted. Our experiments (reciprocal forward masking by electrical and acoustic stimuli) suggest that a direct, instantaneous electrical stimulation of the fibers occurs. We believe that this response to electrical stimulation represents the mean unit response of the auditory nerve fibers. This approach may be useful in the separate study of cochlear and VIIIth nerve functions and in the analysis (deconvolution) of the acoustically evoked compound AP.

Acoustic Stimulation↗