Neoplasm Abducens Schwannoma Inside the Cavernous Sinus Proper: Case Report Toru Nakagawa, M.D.,* Koichi Uchida, M.D., Ph.D.,* Mehmet Faik Ozveren, M.D.,† and Takeshi Kawase, M.D., Ph.D.* *Department of Neurosurgery, Keio University School of Medicine, Tokyo, Japan; †Department of Neurosurgery, School of Medicine, Firat University, Elazig, Turkey Nakagawa T, Uchida K, Ozveren MF, Kawase T. Abducens schwannoma inside the cavernous sinus proper: case report. Surg Neurol 2004;61:559 – 63. BACKGROUND Only 2 cases of abducens nerve schwannoma solely in- side the cavernous sinus have been reported. In both cases, abducens nerve palsy remained after operation. We report the first case of abducens nerve schwannoma inside the cavernous sinus proper with postoperative recovery from abducens nerve palsy. CASE DESCRIPTION The patient was a 47-year-old female who developed left abducens and trigeminal nerve palsies. Neuroradiological examination revealed left intra-cavernous sinus tumor. Total removal of the tumor was performed. The location of the tumor was confirmed intraoperatively inside the cavernous sinus itself, with no relation to the trigeminal nerve. Further, the relation of the tumor to one particular nerve fiber within the abducens nerve bundle was con- firmed inside the cavernous sinus. After surgery, the pa- tient had transient abducens nerve palsy. It had totally disappeared by 6 months. CONCLUSION When the tumor origin is just within the spacious cavern- ous sinus rather than more posterior in the narrow dural tunnel of Dorello’s canal, successful preservation of the nerve function is possible postoperatively through a thor- ough knowledge of the membranous anatomy and careful preoperative study of the radiographic findings. © 2004 Elsevier Inc. All rights reserved. KEY WORDS Abducens schwannoma, intracavernous sinus, functional preservation. S hwannomas account for 8% of intracranial tu- mors [12,24]. Most shwannomas arise from sensory nerves such as the vestibular part of the acoustic nerve and the trigeminal nerve [12,16,24]. Ten abducens nerve schwannoma cases have been reported [1,4,8,10,12,19,20,23,24] and only 2 of them are located inside cavernous sinus [10,24]. We re- port the first case of abducens schwannoma inside the cavernous sinus proper with improvement of abducens palsy after the operation. We also discuss the mechanism of this fortunate recovery of the abducens nerve function in relation to the anatomic characteristics of the abducens nerve, particularly within the cavernous sinus. Case Report A 38-year-old female presented at our hospital be- cause of transient left abducens nerve palsy on October, 1988. On admission, computed tomogra- phy (CT) scanning and magnetic resonance imaging (MRI) at that time revealed a small mass lesion in the posterior cavernous sinus. Although we did not reach a specific diagnosis, we believed the lesion was benign. Therefore, we followed the patient in the outpatient clinic without any operation. The patient stopped attending the outpatient clinic for a period of 5 years. However, in December of 1998, 5 months before admission, she (at 47 years old) complained once more of diplopia and left facial paresthesia. Neurologic examination revealed she had left abducens palsy and left facial paresthesia of the mandibular nerve area. Physical and blood examinations were normal. Horner’s syndrome was not observed. There were no cutaneous manifesta- tions of von Recklinghausen’s disease. MRI revealed an enlargement of the left intracavernous sinus tumor (Figure 1A) and extra cranial protrusion of the tumor through the enlarged foramen lacerum (Figure 1B). The preoperative differential diagnoses Address reprint requests to: Toru Nakagawa, M.D., Department of Neu- rosurgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160 – 8582, Japan. Received March 17, 2003; accepted June 23, 2003. © 2004 Elsevier Inc. All rights reserved. 0090-3019/04/$–see front matter 360 Park Avenue South, New York, NY 10010 –1710 doi:10.1016/S0090-3019(03)00580-9