Angiographically occult vascular malformation of the intracranial accessory nerve: case report

Abstract

A ngiogrAphicAlly occult cerebral vascular malformation (AOVM) is a clinicoradiographic term that describes a heterogeneous group of entities, including cavernous malformations (CMs), thrombosed arteriovenous malformations, venous malformations, capillary telangiectasias, and mixed vascular malformations. 48 These account for 5%-15% of all cerebral vascular lesions, with a general population prevalence estimated at 0.3%-0.5%. Approximately half of AOVMs occur sporadically, while the other half are inherited in an autosomaldominant pattern. Given that histologically most AOVMs are CMs, the current literature concerns patient populations with CMs. Indeed, only a minority of AOVMs are venous malformations, arteriovenous malformations, or mixed vascular malformations. 52,56 CMs are found within the brain parenchyma in approximately 95% of cases, with spinal CMs accounting for 5%. Of the intracranial CMs, 80% are supratentorial and 20% are infratentorial.33 CMs usually have a characteristic appearance on MRI with a mixed T2 signal intensity reticulated core surrounded by a rim of decreased signal intensity. However, smaller lesions can appear as small areas of decreased signal intensity. 24,57 Uncommonly, CMs (as the most common form of AOVMs) can be found within the cavernous sinus, basal cisterns, cauda equina, and cranial nerves. 10,41,43,44 Although CMs have been previously reported to be associated with almost all cranial nerves, their involvement of the lower cranial nerves is extremely rare. We report a case of an angiographically occult vascular malformation (AOVM) arising from the intracranial portion of the spinal accessory nerve, with pathological confirmation of nerve fibers traversing the lesion. case report History and PresentationA 46-year-old woman presented with a history of episodic frontal headaches and episodes of nausea and dizabbreviatioNs AVOM = angiographically occult cerebral vascular malformation; CM = cavernous malformation; SMA = smooth muscle actin. Angiographically occult cerebral vascular malformations (AOVMs) are usually found in the supratentorial brain parenchyma. Uncommonly, AOVMs can be found within the cavernous sinus or basal cisterns and can be associated with cranial nerves. AOVMs involving the intracranial segment of the spinal accessory nerve have not been described. A 46-year-old female patient presented with a history of episodic frontal headaches and episodes of nausea and dizziness, as well as gait instability progressing over 6 months prior to evaluation. Imaging revealed a well-circumscribed 3-cm extraaxial T1-weighted isointense and T2-weighted hyperintense contrast-enhancing mass centered in the region of the right lateral cerebellomedullary cistern. The patient underwent resection of the lesion. Although the intraoperative appearance was suggestive of a cavernous malformation, some histological findings were atypical, leading to the final diagnosis of vascular malformation, not otherwise specified. The patient's postoperative course was uneventful with complete resol...

An isolated cavernous malformation of the sixth cranial nerve: A case report and review of literature

“…[ 27 , 46 , 55 ] Furthermore, only one case has been reported for the involvement of each hypoglossal, accessory, and abducens nerve. [ 13 , 37 , 50 ] Lesions originating from the cerebellopontine angle or the internal auditory canal are more common and may have clinical presentations of cranial nerve CMs, caused by the mass effect of the tumor.…”