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Objective: This study aimed to report our experience in the management of patients with intraoperatively diagnosed intracranial facial nerve schwannomas (FNSs) and propose a decision-making strategy., Methods: Twenty-three patients with FNS of the internal auditory canal and/or cerebellopontine angle operated on between 1992 and 2012 were identified., Results: Preoperatively, all cases have been radiographically diagnosed as vestibular schwannomas. Operative procedures consisted of total tumor resection with grafting in 43.4% of patients, near-total resection leaving behind the tumor capsule overlying the facial nerve in 21.7%, total tumor resection with preservation of anatomic continuity of the facial nerve in 13%, and subtotal resection in 4.3%. Four patients (17.4%) underwent bony decompression with no tumor removal., Conclusion: Management of FNS diagnosed at surgery represents a significant clinical challenge. We considered total tumor resection with grafting when patients presented with preoperative facial nerve palsy (≥ grade III). Both subtotal and near-total tumor removal can be performed in patients with preoperative good facial function and/or large tumors with brainstem compression. Patients with small tumors who were selected for hearing preservation surgery can be considered for bony decompression. Fascicle preservation surgery may be an option when a clear cleavage plane between the tumor and the facial nerve is found., (© The Author(s) 2014.)

Paragangliomas of the cerebellopontine angle are exceptional tumours. We report two cases of paragangliomas of the cerebellopontine angle. To our knowledge, including these two cases, only five cases have been reported in the international literature. The emerging field of genetic study of these tumours will prove critical for their diagnosis and prognosis. The presence of paraganglioma in this area is explained by an abnormal embryologic migration of paraganglionic cells into the cerebellopontine angle, associated with tumorogenesis. These tumors can be associated with others cervico-facial tumours and to genomic abnormalities. The preoperative diagnosis of these tumours is very difficult, with clinical signs like hearing loss, vertigo and tinnitus are very ambiguous. Radiologic assessment of the cerebellopontine angle is also vague. The final diagnosis is only made possible peroperatively and by the post-operative histopathologic study. ENT and neurosurgeons should be awarded of the possible existence of paragangliomas of the cerebellopontine angle, and the necessity of a systemic and genetic assessment.

Background: Acoustic neuroma account for 80% of cerebellopontine angle tumors. Paraganglioma is a rare tumor in this region., Objective: The authors report a case of cerebellopontine angle paraganglioma arising from the anterior inferior cerebellar artery., Results: The clinical and radiologic features were indistinguishable from those of a neuroma, and only the intraoperative view showed a vascular tumor. Definitive diagnosis was made by histopathologic methods., Conclusions: This unique paraganglioma location may be explained by existing embryologic data. The minimal retrosigmoid approach, assisted by endoscopy, allows safe and complete removal of the tumor.

Objective: Clinical study of the keyhole acoustic neuroma retrosigmoid approach for facial nerve and hearing preservation., Study Design: This was a prospective case review from October 1993 to December 1998 in a referral hospital care unit., Patients: A total of 119 consecutive patients with a tumor size of <25 mm in the cerebellopontine angle corrected by a retrosigmoid approach were included in the study., Interventions: Standard audiometric and imaging assessments, complete tumor removal by using endoscopy-assisted control, and nerve monitoring., Main Outcome Measures: House-Brackmann facial nerve grade and hearing level by the American Academy of Otolaryngology-Head and Neck Surgery classification., Results: Grades I and II facial nerve function was obtained in 96% of cases, measurable hearing was preserved in 49% of cases, and 30% of cases achieved serviceable hearing., Conclusion: The retrosigmoid approach is a safe and reliable approach in random patients with small and medium-sized acoustic neuromas.

Sixty patients with primitive hemifacial spasm were treated by means of a minimally invasive retrosigmoid approach in which endoscopic and microsurgical procedures were combined. Intraoperative endoscopic examination of the cerebellopontine angle showed that for 56 of the patients vessel-nerve conflict was the cause of hemifacial spasm. The most common offending vessel was the posterior inferior cerebellar artery (39 patients), next was the vertebral artery (23 patients), and last was the anterior inferior cerebellar artery (16 patients). Nineteen of the patients had multiple offending vascular loops. In one patient, another cause of hemifacial spasm was an epidermoid tumor of the cerebellopontine angle. For three patients, it was not possible to determine the exact cause of the facial disorder. Follow-up information was reviewed for 54 of 60 patients; the mean follow-up period was 14 months. Fifty of the patients were in the vessel-nerve conflict group. Forty of the 50 were free of symptoms, and four had marked improvement. The overall success rate was 88%, and there was minimal morbidity (no facial palsy, two cases of severe hearing loss).

The notion of a neurovascular conflict in the pathogenesis of hemifacial spasm is now well accepted based on evidence obtained from pre-operative imaging and per-operative videoendoscopy of the pontocerebellous angle. We operated 60 patients, 47 women and 13 men, age range 28-79 years, who had hemifacial spasms for 2 months to 30 years. Neurovascular decompression of the facial nerve via the retrosigmoid access was performed using a minimal invasive technique: limited access of short duration, microsurgery, endoscopic and electrophysiologic techniques, positioning of Teflon microsponges between the nerve and the vessels involved. Surgery led to 90% good long-term results with minimal morbidity limited to auditive sequellae in 3.3% of the cases. The site of compression was at the point where the facial nerve emerged in 95% of the cases. Arteries involved were the posteroinferior cerebellous artery (39 cases), the vertebral artery (23 cases) and the anteroinferior cerebellous artery (16 cases). In a third of the cases, the vascular conflict involved more than one vessel. The facial nerve should be isolated from any nociceptive contact to obtain definitive cure.

Unlabelled: To demonstrate the high sensitivity of high definition MRI and particularly "Constructive Interference in Steay State" (Ciss) imaging sequence, in depicting neurovascular conflicts in the CP angle cistern, cisternographic imaging and high definition T1 weighed (Turbo flash), contrast enhanced imaging were used to investigate hemifacial spasm (72 patients) and tinnitus with abnormal BER (5 patients). The study was complemented with Angio MR in 25 patients. The results were compared with findings in a control group of 200 patients, and with the surgical observations in 57 operated cases. In hemifacial spasm, the morphology of the neurovascular conflict was determined, as well as the site of compression (lateral medullary fossa 38 cases; nerve 9; both 15 cases), and the vessel involved (VA 25 cases; PICA 16 cases; AICA 10 cases; VA and PICA 8 cases; VA and AICA 3 cases; lateral medullary vein 1 case). In tinnitus (5 cases), the AICA was involved in every case in the IAM. Among 57 operated cases, only one false negative was observed. In the asymptomatic control group, a nerovascular conflict was observed in 3, 5% of the cases only., Conclusion: CISS imaging is the single most efficient technique, but the combined used of the 3 types of imaging brings the highest diagnostic efficiency, for identifying a neurovascular conflict in the CPA cistern.

The authors present their experience of 191 patients from June 1990 to December 1993 with endoscopy of the cerbellopontine angle using a limited retrosigmoid approach. The advantages of endoscopy of the cerebellopontine angle are the simplicity and efficiency of the procedure, and less invasive surgery. The authors emphasize the importance of the endoscopic procedure: first in acoustic neuroma surgery to get more accurate information about the relationship between the tumour and the adjacent structures, and to control the lateral end of the internal auditory canal; second in hemifacial spasm or facial neuralgia surgery, intraoperative endoscopy is the key point giving a sure and safe way to recognize the offending vessels.

Owing to distal light and panoramic view, the endoscope expands the view inside the cerebellopontine angle without touching the cerebellum or the brain stem and allows clear identification of the vascular and nervous components crossing the cerebellopontine angle. Using a retrosigmoid approach with a combined surgical and endoscopic procedure, the surgeon gets more accurate information to visualize the adjacent structures to a small acoustic neuroma, to check the lateral part of the internal auditory canal, and to locate a vasculonervous cross-conflict. In the future, an endoscopic vestibular neurotomy or an endoscopic microvascular decompression seems to be a possible approach.

An endoscopic approach to the cerebellopontine angle has been suggested by several authors over the last 20 years but it is only recently that the technical and operative conditions for successful endoscopy could be met. The retrosigmoid approach provides simple and direct access to the cerebellopontine zone. The endoscope, with its distal light source, provides excellent illumination of a wide visual field within an anatomical site particularly rich in neurovascular structures. Endoscopic and microsurgical techniques may be combined for the surgical management of acoustic neuroma with the advantage of assuring better exposure of structures adjacent to the tumor and better control of the quality of dissection of the fundus of the internal auditory canal. The addition of endoscopic techniques, during surgery for trigeminal neuralgia or unilateral facial spasm, makes it possible to accurately locate the site of neurovascular compression without either retraction of the cerebellum or unnecessary dissection.