Clinical Features of Angiographically Occult Vascular Malformation

=Abstract=A retrospective review of 22 cases of angiographically occult vascular malformations (AOVMs), treated at our institution during the past 6 years, was conducted to define better the clinical and radiological manifestations as well as the effective treatment modality of these lesions. There were 12 (54.5%) arteriovenous malformations (AVMs), 8 (36.4%)cavernous angiomas, 1 (4.5%) venous angioma, and 1 (4.5%) unclassified vascular malformation. The most frequent initial presentations included hemorrhages in 72.7% of the patients, seizures in 22.7%, and compression by mass lesion in 4.5%. Of the 16 hemorrhagic cases. 11 (58.7%) were AVMs and 3 (18.7%) were cavernous angiomas. The remaining 2 cases were a venous angioma and an unclassified vascular malformation. In almost all of the AVMs (11112) the initial presentations were hemorrhages. Nine cases of AOVMs (40.9%) developed recurrent hemorrhages as confirmed by clinical, radiological, and operative features. All of the MRI findings performed in the 17 cases showed thick circumscribed hypodense rims on T2-weighted images representing hemosiderin deposits. Various central intensities suggested the presence of hematomas in different stages. Twenty patients underwent surgery with total excision and subsequent good results. Two patients, one with a pontine lesion and the other with a middle cerebellar peduncle lesion, underwent partial excision associated with consequent persistent neurological deficits. This report suggests that the AOVMs are prone to cause hemorrhages or neurological deficit and surgical excision can provide an effective and safe treatment modality for this disease entity.