Intracranial facial nerve anastomosis

A technique of intracranial facial nerve anastomosis using fenestrated collagen splints was used in eight patients operated upon for acoustic neuroma or glomus temporale tumor. This technique is rapid and simpler than suturing in the cerebellopontine angle. Clinical results are as good as or even better than those obtained with more peripheral facial nerve anastomosis or grafting. An animal study demonstrated no undue histologic reaction to the collagen splints.     

Free vascularized nerve grafting for immediate facial nerve reconstruction

OBJECTIVES/HYPOTHESIS: To obtain better functional results after reconstruction to treat facial palsy in the patients with preoperative and intraoperative factors that might inhibit functional recovery, the authors have used free vascularized nerve grafts to immediately reconstruct severed facial nerves. STUDY DESIGN: The indications for vascularized nerve grafts were 1) scarred recipient bed attributable to previous operations, 2) a history of previous irradiation at the wound, 3) facial skin defects over the nerve graft after tumor ablation, 4) patient age greater than 60 years, and 5) preoperative facial palsy. METHODS: Four types of free vascularized nerves were used. Functional recovery after reconstruction could be assessed with two facial nerve grading systems.Ten patients who underwent immediate reconstruction of severed facial nerve after ablative surgery of malignant tumors of the parotid gland were reviewed. RESULTS: Functional recovery after reconstruction could be assessed with the House-Brackmann grading system and a 40-point grading system in 6 of the 10 patients after a mean follow-up period of 29.8 months (range, 10-60 mo). Results with the House-Brackmann system were grade II in 1 patient, grade III in 4 patients, and grade IV in 1 patient; scores on the 40-point grading system were 20 in 1 patient, 22 in 3 patients, 24 in 1 patient, and 28 in 1 patient. CONCLUSION: The study results indicated that muscle movement recovers satisfactorily after free vascularized nerve grafting. Although a study comparing vascularized nerve grafts and conventional nerve grafts would be necessary to confirm the superiority of vascularized nerve grafts, free vascularized nerve grafts are effective for immediate reconstruction of the severed facial nerve in patients with preoperative and intraoperative factors that might inhibit functional recovery.     

Intracranial supramaximal facial nerve stimulation: A murine model

Purpose

Supramaximal facial nerve stimulation is an applied current sufficient to evoke a maximal electromyographic response of facial musculature. It is used during cerebellopontine angle surgery for prognostication of postoperative nerve function. We utilized a rat model to examine safe parameters for intracranial electrical stimulation.

Materials and methods

Intracranial facial nerve stimulation with electromyographic monitoring of 14 rats was performed. Supramaximal current level was determined and 50 additional pulses of supramaximal (4 rats), 3 times supramaximal (4), 10 times supramaximal (3), or zero (3) current were applied. To monitor progression of facial nerve injury, video recordings of vibrissae movements and eye closure were captured at 1, 3 and 28 days after surgery; animals were sacrificed on day 28, when nerve morphometry was performed.

Results

One rat in the supramaximal stimulation group (of 4), and one rat in the 10 times supramaximal stimulation group (of 3) demonstrated persistent impairment of facial nerve function as evidenced by decreased amplitude of vibrissae sweeping and eye closure impairment. The remainder of rats in all experimental groups demonstrated symmetric and normal facial nerve function at all time points.

Conclusions

A novel animal model for supramaximal stimulation of the rat intracranial facial nerve is described. A small proportion of animals demonstrated functional evidence of nerve injury postoperatively. Function was preserved in some animals after stimulation with current order of magnitude higher than supramaximal levels. Further study with this model is necessary to definitively isolate the effects of surgical trauma from those of supramaximal electrical stimulation.     

Intratemporal facial nerve neurinoma without facial paralysis.

A 38-year-old man was referred by his general practitioner to our department on 28 October 1991, with a 2-week history of vertigo. A left aural polyp was identified. The audiogram showed a moderate conductive loss on the left side. Computed tomography (CT) and magnetic resonance imaging (MRI) confirmed the presence of the expanding lesion in the descending portion of the facial nerve. However, there was no seventh nerve paresis. At operation, the neurinoma (Schwannoma) filled the middle ear cleft and extended from the genu to the stylomastoid foramen. The floor of the middle ear had been eroded, exposing the jugular bulb. Facial nerve paresis is the usual presenting feature of a facial neurinoma. The case is presented for the reason that the absence of facial palsy as a presenting feature is rather rare, especially in the cases with large tumor and extensive bone erosion.     

Testing facial nerve function.

A variety of facial nerve tests are now available. These tests can aid the clinician in discerning the site of lesion, estimating prognosis, assessing evidence of neoplastic or infectious involvement, and assisting in intraoperative facial monitoring.     

Intracanalicular facial nerve schwannoma.

OBJECTIVE: To investigate the capability of preoperative evaluations in predicting the precise anatomic origin of intracanalicular tumors. STUDY DESIGN: We conducted a retrospective case review. SETTING: Tertiary referral center. PATIENTS: A total of 11 patients (8 men and 3 women, 26-70 years old) with intracanalicular tumors who were treated surgically were included. INTERVENTIONS: Pure-tone average, auditory brainstem response, caloric test, and temporal magnetic resonance imaging were done in all 11 patients. Electroneuronography has only been performed since 2003, and only 3 patients were evaluated. MAIN OUTCOME MEASURE: Preoperative symptoms, pure-tone average, auditory brainstem response, caloric test, electroneuronography, and magnetic resonance imaging were compared between patients with facial nerve schwannomas and patients with vestibular schwannomas. RESULTS: Postoperatively, facial nerve schwannomas were diagnosed pathologically in 2 (18%) of 11 patients. There were not any clues suggesting facial nerve schwannoma in preoperative evaluations. CONCLUSION: A facial nerve schwannoma may be misdiagnosed as a vestibular schwannoma, especially when the tumor is confined to the internal auditory canal. There are no useful preoperative evaluation tools in predicting the precise nerve origin of intracanalicular tumors. These emphasize the need to fully inform the patient preoperatively.     

Intraoperative facial nerve monitoring.

Facial nerve monitoring is one of the most exciting innovations in otologic surgery in the past decade. Intraoperative monitoring has been shown to reduce the probability of iatrogenic injury to the facial nerve during surgery. It saves surgical time and reduces the anxiety level of both patients and surgeons. There are several reasons to use facial nerve monitoring: The surgeon nerve knows when it will be needed in a particular case, the operating room personnel become familiar with the equipment, and the surgeon learns how to interpret the sounds produced by the monitor and how to correlate them with surgical manipulations around the facial nerve. Facial nerve monitoring has added another dimension of safety to otologic and neurotologic surgery and has reduced the incidence of facial weakness or paralysis in the authors' surgical practice.     

Transtemporal facial nerve schwannoma without facial nerve paralysis

Facial schwannoma is a relatively rare but well documented lesion, presenting either as a mass or with facial nerve symptoms. In this report, an extensive facial schwannoma, extending from the brain stem to the periphery with minimal facial nerve symptoms and normal facial function is presented.     

Management of facial nerve paralysis.

Facial paralysis is a dreaded complication of parotid surgery. It can lead to a variety of troubling symptoms in the patient, such as ocular problems and nasal obstruction. It can also have a significant emotional impact on the patient because of facial disfigurement and difficulties with communication, eating, and drinking. Successful outcome for patients inflicted with facial paralysis depends on proper selection of the appropriate rehabilitation technique. This article discusses the acute and late management of facial paralysis resulting from parotid surgery.     

Rehabilitation of facial nerve palsy.

Forty-nine patients underwent 158 procedures (including 19 revisions) for complete facial palsy. The variety of causes of facial palsy are enumerated, with the various procedures used to rehabilitate the face. Some improvement is invariably achieved. It is concluded that a readiness to intervene with a wide choice of procedures as early as realistically possible offers the best outcome in function and cosmetic appearance.     

Computer-aided 3-D reconstruction and measurement of the facial canal and facial nerve. I. cross-sectional area and diameter: Preliminary report

Using a computer-aided three-dimensional (3-D) reconstruction method, measurements were made at eight representative sites of diameters and the cross-sectional area of the facial canal, facial nerve, and the space between the canal and nerve. Materials used were serial histology sections of seven normal human temporal bones obtained from individuals of different ages. Two areas of decreased cross-sectional area of the facial canal were found: the proximal part of the labyrinthine portion and the middle part of the tympanic portion. These narrowings in the canal appeared to be correlated with decreased superior-inferior diameter of the facial canal in those portions, espcially in adult temporal bones, and also with decreased cross-sectional area, both of the nerve and of the space between the canal and the nerve, in these portions. The developmental etiology of these narrowings is speculated on, and their possible relationship to Bell's palsy is discussed.     

An animal model of ischemic facial palsy. Behavioral facial nerve function and ultrastructural changes of the facial nerve

We investigated facial palsy which was induced by the interruption of the petrosal artery in guinea pigs. Forty animals were observed for 2 months regarding their behavioral facial nerve function and assessed by the blink reflex. Morphological changes in the intratemporal portion were observed with transmission electron microscopy in 20 animals with an interrupted petrosal artery. Facial palsy developed in 85.0% within 3 days after the interruption. The degree of palsy varied from mild to severe. Remission of palsy required 2-3 months in severe cases, 3 weeks or less in mild/moderate cases. Histological studies revealed a striking difference in the degree of degenerative changes between severe cases and mild/moderate cases. Animals with severe palsy showed extensive axonal atrophy and myelin disruption from the early stage. Meanwhile, degenerative changes were slight in cases with mild/moderate palsy. Regenerating unmyelinated fibers appeared 1 week after the interruption, but diminished in number 4 weeks later. Thereafter, new myelin was reformed on fibers. In cases of severe nerve damage, however, this regeneration process did not always seem to work well. A decrease in number and an irregular shape of the fibers were noted in animals with incomplete recovery. This animal model may be helpful for understanding the pathophysiology of ischemic facial palsy.     

Gunshot wounds to the facial nerve.

OBJECTIVE: This paper presents our experience with gunshot wounds to the temporal bone and discusses facial nerve lesions, surgical indication, surgical timing, and other findings. STUDY DESIGN: We performed a retrospective review of patients treated for facial nerve lesion after gunshot injury to the temporal bone. SETTING: The study was performed in the Otolaryngology Department of the University of Sao Paulo Medical School, Sao Paulo, Brazil. PATIENTS: Ninety-eight patients treated between 1988 and 1999 were analyzed. INTERVENTION: Facial nerve lesions, bullet locations, and surgical techniques were analyzed. Patients were monitored for 2 years. RESULTS: Gunshot trauma to the temporal bone presented considerable tissue loss resulting from the abrasion effect and severity of the impact. The third segment of the facial nerve was most affected, and the bullet was typically found lodged in the mastoid tip. Postoperative infection was common. Such cases required revision surgery, resulting in worse cosmetic outcomes than in cases of closed trauma. CONCLUSIONS: Surgical exploration of the facial nerve should be performed as soon as possible, since long delays increase the chance of traumatic neuroma and more pronounced scarring around the facial nerve. Open mastoidectomy with meatoplasty is the surgical technique recommended for repairing the mastoid and the facial nerve. In the majority of cases, a cable graft is necessary. Since nerve lesion in proximity to the stylomastoid foramen and extratemporal facial nerve is common, these areas must be explored carefully.     

Surgical landmarks for the facial nerve.

A number of different approaches can be used to expose the facial nerve. The route taken will depend on the pathology and the portion of the nerve that requires exposure. When performing a parotidectomy approach to the extratemporal portion of the facial nerve, the tragal pointer is a key landmark, but other landmarks also should be used to identify the facial nerve safely. The lateral semicircular canal, the chorda tympani nerve, the digastric ridge, and the cochleariform process are some of the useful landmarks in the mastoid and middle ear. When performing a middle fossa approach, the superior semicircular canal, the greater petrosal nerve, and a window through the tegmen tympani into the attic are useful guideposts. The surgeon should use as many of the available landmarks as feasible to perform safe facial nerve surgery.