Giant arteriovenous malformation of the insula

Case Report: A 23-year-old male, sought care due to paraesthesia in the left upper limb (LUL) and left hemiface paresis. He was submitted to CT and angiography that revealed giant arteriovenous malformation (AVM) of 61mm (in its max diameter) from the right middle cerebral artery in the region of the insula. The venous drainage was performed for the superior sagittal and right transverse sinuses and there was presence of intranidal aneurysm in a branch of the lateral lenticuloestriate artery. 2 days after, he presented sudden right hemicranial headache of strong intensity and vomiting. Emergency CT confirmed a massive intraparenchymal hematoma, determining midline shift, erase of the sulci and of the silvyan cistern. The patient was then submitted to clipping and resection of the AVM, which had a surgical time of 9 hours due to the difficulty of access. Postoperative period was marked by elevated intracranial pressure, which was managed in the ICU, and developing of hemiparesis at left, (strength grade 0) in LUL and (grade 2) in left lower limb.

Discussion: Brain AVMs occur in about 0.1 percent of the population, 10% of the incidence of intracranial aneurysms, and supratentorial lesions account for 90 percent of the cases. Giant intracranial AVM’s are defined with diameter > 6 cm. They constitute 3–4% of all AVMs and pose management challenges because of their complex angioarchitecture and frequent involvement of eloquent regions. The symptoms and natural history of giant AVMs are unpredictable; it most frequently presents with hemorrhage and seizures, with other presentations including headaches or focal deficits related to the location of the AVM. Although the hemorrhagic risk of giant AVMs has yet be quantified, the association of smaller lesion size with higher risk of hemorrhagic presentation has previously been concluded by many studies. Therefore, conservative management has generally been recommended. Surgery is usually reserved for patients with deterioration and those with bleeding by rupture the AVM. Common regimens include embolization only, embolization followed by microsurgery or radiosurgery, and a combination of all modalities. Prognosis for the intervention elected patients include mortality of 10–15%, obliteration of 60–95%, and good functional outcomes at follow-up in 50–70%.

Conclusion: Despite general consensus on management strategy, the natural history of giant AVMs is poorly understood because of the rarity of these lesions.