Management of intraparotid facial nerve schwannomas

BACKGROUND: The purpose of the present paper was to review the management of intraparotid facial nerve schwannoma so as to discuss its clinical presentation, evaluate the various possible diagnostic investigations, and compare the various surgical options and outcome. METHODS: Case series was undertaken of five (1.3%) patients with facial nerve schwannoma out of 400 consecutive parotidectomies at Singapore General Hospital. RESULTS: There were three men and two women with an age range of 29-65 years. Three patients presented with painless parotid lumps while two had painful parotid swellings. None had facial nerve paresis. Only one patient had preoperative diagnosis suspicious of schwannoma by fine-needle aspiration cytology (FNAC). Diagnoses were made intraoperatively. Four patients had excision with cable grafting of the nerve defect. achieving facial nerve grade II-IV (House-Brackmann scale). One patient who underwent enucleation of tumour with nerve preservation achieved grade II. CONCLUSIONS: Preoperative diagnosis is difficult but it is important for discussion of the extent and options of surgery. Fine-needle aspiration cytology holds promise in making a preoperative diagnosis. Enucleation with nerve preservation where possible seems to offer better facial function whereas nerve excision with cable graft can give satisfactory results.     

Split facial nerve course in vestibular schwannomas

OBJECT: The facial nerve in vestibular schwannomas (VSs) is located on the ventral tumor surface in more than 90% of cases; other courses are rare. A split facial nerve course with two distinct bundles has thus far been described exclusively for medial extrameatal tumors. METHODS: Between 1996 and 2005, 16 consecutive cases of 241 surgically treated VSs were observed to have distinct splitting of the facial nerve. The mean tumor size measured 27 mm. In one third of the cases, intrameatal tumor extension with obliteration of the fundus was documented. All patients underwent extensive intraoperative neurophysiological monitoring using multichannel electromyography recordings. Patients were reevaluated 12 months after surgery. In all 16 patients, distinct splitting of the facial nerve was demonstrated. The major portion of the facial nerve followed a typical course on the ventral tumor surface. The smaller nerve portion in all cases ran parallel to the brainstem up to the level of the trigeminal root exit zone and crossed on the cranial tumor pole to the internal auditory canal. The two nerve portions rejoined at the level of the porus acusticus. The smaller portion carried fibers exclusively to the orbicularis oris muscle, whereas the major portion supplied all three branches of the facial nerve. CONCLUSIONS: In VSs, an aberrant course with distinct splitting of the facial nerve adds considerably to the surgical challenge. Long-term facial nerve results are excellent with extensive neurophysiological monitoring, which allows the differentiation and identification of aberrant facial nerve fibers and avoids additional risks to facial nerve preservation.     

Side-to-end hypoglossal-facial anastomosis via transposition of the intratemporal facial nerve

Summary The technique of facial nerve repair with side-to-end hypoglossal-facial anastomosis is presented and evaluated in five patients who were operated on for facial nerve paralysis after acoustic schwannoma surgery, or had cranial base trauma. The end-to-end hypoglossal-facial anastomosis is accompanied by hemilingual paralysis, with difficulty in swallowing, chewing and speaking. In this new technique, the facial nerve is mobilised in the temporal bone, transected at the second genu and transposed to the hypoglossal nerve where a tensionless side-to-end anastomosis is performed. The hypoglossal nerve is transected in oblique fashion to about one third of its circumference. We were able to achieve a tensionless anastomosis in all patients. The idea is to bring about re-innervation of the previously denervated tissue via a collateral sprouting of axons of the donor nerve through the site of coaptation without sacrificing the innervation of the donor nerve’s original targets. With side-to-end hypoglossal-facial anastomosis, two patients attained a House- Brackmann grade of III (one of them with independent movement of eyelids and mouth); one achieved grade IV, another grade V and grade VI. No patient had hemilingual atrophy nor any problems associated with swallowing or chewing.     

Intracranial facial nerve schwannomas. Seven cases reviewed

BACKGROUND AND PURPOSE: Intracranial facial nerve schwannomas are rare neoplasms. Preoperative diagnosis is difficult because of non-specific clinical presentations (deafness, facial paralysis sudden or progressive) and radiological differential diagnosis (petrous bone tumor, vestibular schwannoma). Treatment depends on localization and has to be discussed for each case. METHODS: Seven cases (four men and three women) of intracranial facial nerve schwannomas were retrospectively studied. RESULTS: Before treatment, we found deafness in six cases (two sudden and four progressive), a facial palsy in five cases (three sudden and two progressive). Five patients had deafness and facial palsy. One patient had only headache. Three schwannomas were supra and intra-petrous, two in the cerebello-pontine angle, and two were plurifocal (petrous bone, internal auditive canal and cerebellopontine angle). Six patients were operated on with an oto-neurosurgical procedure. After treatment, facial palsy always worsened (requesting secondary hypoglosso-facial anastomosis in cinq cases). Only one case of transmission deafness improved after ossiculoplasty. One patient is still under clinical and radiological observation. CONCLUSION: Diagnosis is difficult and made operatively in half of patients. A large tumor requires surgery, but surveillance can be a good option for a small one, considering the risk of postoperative facial palsy.     

Intracranial and intratemporal facial neuroma

Primary tumors of the facial nerve are relatively rare and have a variety of presenting symptoms. This article reviews 248 cases of facial neuroma in the world's literature and adds seven cases that were managed at the Baylor College of Medicine. Facial weakness was most common symptom, with facial spasm or tics, hearing loss, and masses in the external auditory canal also being frequently seen. At surgery, the tympanic, vertical, and labyrinthine segments were the most commonly involved areas. On the basis of this review, general principles have been drawn up to help the clinician in diagnosis and management of this (at times) difficult problem.     

Traumatic intratemporal facial nerve injury: management rationale for preservation of function

A retrospective review of 29 cases of intratemporal facial nerve injuries included 18 temporal bone fractures, 7 gunshot wounds, and 4 iatrogenic complications. Surgical exploration confirmed involvement of the fallopian canal in the perigeniculate region in 14 longitudinal and 3 transverse or mixed fractures of the petrous pyramid. Gunshot and iatrogenic injuries usually occurred within the tympanic and vertical segments of the facial canal and at the stylomastoid foramen. When hearing is salvageable, the middle fossa approach provides the best access to the perigeniculate region of the facial nerve. In the presence of severe sensorineural hearing loss, the transmastoid-translabyrinthine approach is the most appropriate for total facial nerve exploration. Grade I to III results can be anticipated in timely decompression of lesions caused by edema or intraneural hemorrhage. Undetectable at the time of surgery, stretch and compression injuries with disruption of the endoneural tubules often lead to suboptimal results. Moderate-to-severe dysfunction (Grade IV), with slight weakness and synkinesis, is the outcome to be expected from the use of interpositional grafts.     

Large facial nerve schwannomas without facial palsy: case reports and review of the literature

Although approximately 30% of facial nerve schwannoma cases present with no facial palsy, a large facial nerve schwannoma extending to the middle and posterior cranial fossa quite rarely presents without facial palsy. The authors encountered two patients with large facial nerve schwannoma who presented with only hearing impairment and no facial palsy. The first patient was a 64-year-old woman who presented with right auditory impairment without facial palsy. MR images demonstrated a dumbbell-shaped tumor in the cerebellopontine angle. Another patient, a 40-year-old woman, also presented with vertigo and right tinnitus without facial palsy. MR images demonstrated a huge tumor expanding into both the posterior cranial fossa and middle cranial fossa. In both cases, intraoperative findings confirmed that the tumors had grown from the facial nerve. Facial nerve schwannoma can be easily diagnosed if detailed neurological evaluations and appropriate neuroimagings are conducted. However, in spite of such huge tumoral size and expanding pattern, the facial nerve function was relatively preserved. Anatomical features of the facial schwannoma are discussed. A tumor extending to the middle and posterior cranial fossa should remind neurosurgeons to consider facial nerve schwannomas even in the absence of facial palsy.     

High resolution computed tomographic scanning in the detection of intratemporal neuromas of the facial nerve

Continued refinements in the technique of high resolution computed tomographic scanning now allow the study of the pathology of intratemporal tumors of the facial nerve. The normal anatomy of this area and a selected case of facial nerve neuroma diagnosed with high resolution computed tomography are presented.     

Facial nerve schwannomas

A study of 26 patients with facial nerve schwannomas treated at the University Hospital of Zurich was done. The general clinical features are described, but particular emphasis is placed on tumor histologic findings, recovery of facial function after grafting, and the nature of intracranial facial nerve schwannomas Presenting symptoms are stratified by tumor location, with facial dysfunction being commonest with intracranial tumors, neurotologic symptoms being associated with intracranial tumors, and parotid masses being a feature of extratemporal tumors. We found no differences in tumor histology regardless of site of origin. Clinical, histologic, and radiologic evidence is reviewed, and from this evidence we conclude that intracranial facial nerve schwannomas may be particularly invasive acoustic schwannomas. Recovery of facial movement after grafting the facial nerve is not influenced by graft length or graft type. Prolonged preoperative facial dysfunction has a negative influence on recovery after grafting.     

Suboccipital retrosigmoid approach for removal of vestibular schwannomas: facial nerve function and hearing preservation

In this report, we discuss the pertinent bony, arachnoid, and neurovascular anatomy of vestibular schwannomas that has an impact on the surgical technique for removal of these tumors, with the goal of facial nerve and hearing preservation. The surgical technique is described in detail starting with anesthesia, positioning, and neurophysiological monitoring and continuing with the exposure, technical nuances of tumor removal, hemostasis, and closure. Positive prognostic factors for hearing preservation are also highlighted.     

Bilateral vidian nerve schwannomas associated with facial palsy. Case report and review of the literature

Intracranial schwannomas are relatively common benign tumors arising from Schwann cells. Among the cranial nerves, the vestibular division of the vestibulocochlear nerve is the site most commonly affected by these lesions, followed by the trigeminal nerve. The authors report a case of bilateral schwannomas arising from both of the pterygoid canals. A 13-year-old girl presented with intermittent headaches and left-sided facial palsy. Preoperative computerized tomography scans and magnetic resonance images revealed nonenhancing round masses within the bilateral vidian canals, bone erosion, and sclerosis. The transnasal transseptal transsphenoidal approach was used to remove the masses. Postoperatively, the patient recovered uneventfully. On histopathological examination, the masses were confirmed as schwannomas. The clinical presentation and probable histogenesis of schwannomas arising in this location are discussed together with a review of the literature.     

Resection of large vestibular schwannomas: facial nerve preservation in the context of surgical approach and patient-assessed outcome

OBJECT: Vestibular schwannoma surgery has evolved as new therapeutic options have emerged, patients' expectations have risen, and the psychological effect of facial nerve paralysis has been studied. For large vestibular schwannomas for which extirpation is the primary therapy, the goals remain complete tumor resection and maintenance of normal neurological function. Improved microsurgical techniques and intraoperative facial nerve monitoring have decreased the complication rate and increased the likelihood of normal to near-normal postoperative facial function. Nevertheless, the impairment most frequently reported by patients as an adverse effect of surgery continues to be facial nerve paralysis. In addition, patient assessment has provided a different, less optimistic view of outcome. The authors evaluated the extent of facial function, timing of facial nerve recovery, patients' perceptions of this recovery and function, and the prognostic value of intraoperative facial nerve monitoring following resection of large vestibular schwannomas; they then analyzed these results with respect to different surgical approaches. METHODS: The authors retrospectively reviewed a database of 67 patients with 71 vestibular schwannomas measuring 3 cm or larger in diameter. The patients had undergone surgery via translabyrinthine, retrosigmoid, or combined approaches. Clinical outcomes were analyzed with respect to intraoperative facial nerve activity, responses to intraoperative stimulation, and time course of recovery. Eighty percent of patients obtained normal to near-normal facial function (House-Brackmann Grades I and II). Patients' perceptions of facial nerve function and recovery correlated well with the clinical observations. CONCLUSIONS: Trends in the data lead the authors to suggest that a retrosigmoid exposure, alone or in combination with a translabyrinthine approach, offers the best chance of facial nerve preservation in patients with large vestibular schwannomas.     

Microsurgical results with large vestibular schwannomas with preservation of facial and cochlear nerve function as the primary aim

Summary Objective. To evaluate our microsurgical results in dealing with vestibular schwannomas (VS) greater than or equal to 30 mm when preservation of cranial nerve function was considered more important than total tumour removal.Methods. Sixteen consecutive cases were operated on by the same neurosurgeon according to a prospective protocol using intraoperative neuro-monitoring (IONM) based on electromyographic and brain stem auditory evoked potential recordings. Facial nerve function was evaluated on the House-Brackmann Scale and cochlear nerve function on the Gardner-Robertson Scale. Someone not involved in the clinical management of our patients collected all data.Results. Fifteen patients showed facial nerve (FN) function of House-Brackmann grade (HBG) I or II at one year postoperatively and one kept the HBG IV she had preoperatively. Two patients of four maintained a cochlear nerve function of Gardner-Robertson grade (GRG) II. The tumour excision rates were: total, 68.7%; near total, 6.3%; subtotal, 18.7%, and partial, 6.3%. The average follow-up was 55 months (1–106). Three patients underwent radiotherapy later with growth stabilisation and no additional morbidity.Conclusion. When dealing with VS greater than or equal to 30 mm, microsurgery guided by IONM, with a rate of total or near-total tumour excision of about 75%, can retain socially acceptable facial nerve function (HBG I or II) in all cases and serviceable hearing (GRG I or II) in two cases out of four. Maintaining serviceable cranial nerve function should take precedence over total tumour excision.