The outermost "dura-like membrane" of vestibular schwannoma.

BACKGROUND: The membranous structure of vestibular schwannoma is an important factor in its surgical treatment. Herein, we report intraoperative and microscopic findings relating to an outermost dura-like membrane in cases of vestibular schwannoma and the importance of these findings. METHODS: Intraoperative findings of 16 cases of vestibular schwannoma treated with an initial surgery were studied with an aim to determine if the cases had a dura-like membrane. Then we studied microscopic findings of the dura-like membrane using hematoxylin and eosin, Masson trichrome, and immunohistochemical staining in 2 cases. RESULTS: The dura-like membrane was observed in 8 out of 16 cases. The average tumor size of the cases that had a dura-like membrane was 30 ± 8.1 mm, and Koos grading 4 was in 7 out of 8 cases, and one was grade 3. In cases without a dura-like membrane, these values were significantly smaller, with an average tumor size of 12.8 ± 5.2 mm, and Koos grading 4 was only in 1 of 8 cases, grade 3 was in 2 cases, and other 5 cases were grade 2. The outermost dura-like membrane enveloped the vestibular schwannoma around the internal acoustic meatus and was continuous with the dura mater. Reactive angiogenesis was observed in the dura mater. Microscopic findings proved its continuity with the dura mater. In one case, the facial nerve was damaged before it was identified during subcapsular dissection. In that case, the dura-like membrane negatively affected our ability to identify the facial nerve. CONCLUSIONS: A dura-like membrane sometimes envelops vestibular schwannoma around the internal acoustic meatus. Recognition of this membranous structure is important for the surgical preservation of facial and acoustic nerves.

Simultaneous decompression of the orbital lateral wall and optic canal for fibrous dysplasia in early adolescence.

INTRODUCTION: Patients with fronto-orbital fibrous dysplasia (FD) occasionally present fronto-orbital protrusion, exophthalmos, and visual acuity disturbance. Simultaneous management of these conditions has not been previously described. CASE DESCRIPTION: A-10-year-old female with fronto-orbital FD complained of left visual acuity disturbance. Head computed tomography showed compressed optic canal secondary to thickened bone. Decompression of the optic canal via the left frontotemporal extradural approach, opening of the lateral orbital wall, and dissection of the prominent zygoma were done simultaneously. The patient's visual acuity disturbance and exophthalmos subsequently improved postoperatively. DISCUSSION AND EVALUATION: When optic canal decompression is performed by the fronto-temporal approach, opening of the lateral orbital wall can be done simultaneously to decrease the intraorbital pressure and to prevent exophthalmos. In addition, although aesthetic plastic surgery is not generally recommended during the growing phase (due to the possibility of recurrence), this approach can prevent skin loosening and adverse cosmetic outcomes. CONCLUSIONS: Aesthetic plastic surgery for fronto-orbital FD is recommended to prevent skin loosening. Opening of the lateral orbital wall should be performed when optic canal decompression is planned.

Vascularized middle turbinate flap for the endoscopic endonasal reconstruction of the anterior olfactory groove.

A vascularized middle turbinate flap (MTF) might be useful in the repair of lesions in the anterior olfactory groove. The sizes of the MTF and inferior turbinate flap (ITF) and these distances up to the frontal base were analyzed by computed tomography (CT) using a picture archiving and communication system (PACS) in 20 patients. The minimum flap measurement to reconstruct the skull base was defined as the distance from the basal plate to the medial slope or lateral slope edge of the MTF and the ITF on the coronal view. Next, we reviewed clinical data from three patients with dural deficits who underwent endoscopic vascularized MTF reconstruction. The distance to the frontal base from the ITF was significantly longer than that from the MTF. The minimum length of the MTF measured by coronal CT was similar to the distance to the frontal base. In contrast, the minimum length of the ITF was shorter than the distance to the frontal base. These results suggest that the MTF might be superior to the ITF for coverage of the anterior frontal base. Three patients who underwent MTF reconstruction for a defect in the anterior olfactory groove had good outcomes and no complications. The MTF is a good option for reconstruction of defects in the anterior part of the olfactory groove.

Intraosseous Schwannoma of the Petrous Apex.

Background and Importance Intraosseous schwannoma is a relatively rare clinical entity that typically arises in vertebral and mandibular bone. Intraosseous schwannoma located entirely within the petrous bone is exceedingly rare, and only two cases have been reported to date. Clinical Presentation A 47-year-old Asian man was referred to our hospital with a chief complaint of double vision. Neurologic examination revealed left abducens nerve palsy. Radiologic imaging showed a 35-mm osteolytic expansive lesion located in the left petrous apex. We made a preoperative diagnosis of chondrosarcoma and performed surgical resection. Surgery was performed via a left subtemporal epidural approach with anterior petrosectomy. The histopathologic diagnosis of the tumor was schwannoma. Schwannoma arising from cranial nerves was excluded from intraoperative findings in conjunction with the results for cranial nerves, and intraosseous schwannoma was diagnosed. Postoperative course was uneventful, and abducens nerve palsy resolved immediately after surgery. Conclusion The differential diagnosis of intraosseous schwannoma should be considered for an osteolytic mass lesion within the petrous apex. Subcapsular tumor removal was considered ideal in terms of preservation of the cranial nerves and vessels around the tumor.