Repermeation of partially embolized cerebral arteriovenous malformations: a clinical, radiologic, and histologic study.

PURPOSE To describe the pattern and time course of embolization-related tissue lesions and repermeation of the intranidal cast after endovascular embolization of cerebral arteriovenous malformations (AVMs) with N-butyl cyanoacrylate (NBCA). METHODS We retrospectively reviewed the records of 26 patients who were treated by endovascular embolization with NBCA and subsequent surgical extirpation to look for embolization-related tissue lesions and repermeation of the cast. A residual flow through the malformation was identified on preoperative angiograms in every case. RESULTS Pattern and time course of embolization-related tissue lesions were typical. Until 3 months after embolization, repermeation of embolized structures did not occur. In contrast, repermeation was found in every patient who had surgery later than 3 months after the first embolization (n = 13; 50%). In these cases, histologic examination of the resected nidus disclosed capillary structures inside the lumen of embolized vessels. Capillaries were traced immunohistochemically with antibodies against membrane-bound factor VIII. No parameter other than the interval between the first embolization and surgery was found to relate to the repermeation of the cast. CONCLUSION Intranidal recapillarization can occur later than 3 months after the first embolization with NBCA if total and solid casting of the nidus was not accomplished.