A 7-month-old male infant without perinatal medical history presented with generalized tonic-clonic seizure sustained for 30 minutes with relapsing pattern. After administration of 1 mg of lorazepam, seizure was subsided and levetiracetam was administered additionally. Initial Glasgow coma scale was E1V1M2 with decerebrated posture and the patient was hyperventilating. Both pupil size was fixed at 2 mm without light reflex and anterior fontanelle was bulged. Immediate brain computed tomography (CT) was performed and there was thick subarachnoid hemorrhage at basal cistern with massive intraventricular hemorrhage. Additional CT angiography showed ruptured proximal A2 segment of ACA aneurysm (Fig. 1).

To control increased intracranial pressure, extraventricular drain catheter was first inserted at right Kocher’s point under general anesthesia and then the patient was transferred to angioroom. Femoral artery catheter was inserted with ultrasonogram, and 4 French Davis diagnostic catheter was placed at left internal carotid artery (ICA) without femoral sheath. In initial transfemoral cerebral angiography (TFCA), the aneurysm had a fusiform shape covering the entire A2, including the origin of the orbitofrontal artery in the proximal A2 just above the fenestration channel. The aneurysm was close to 6 mm in size with multiple blebs and appeared to have ruptured at the superior part. An aneurysm-sized pseudoaneurysm was seen around the rupture point and contrast leakage was consistently observed during TFCA and coiling. There were no certain angiographic findings suggestive of dissection, and an accurate diagnosis was difficult due to failure of magnetic resonance imaging. However, this is a fusiform aneurysm covering the entire A2 segment and considering that pediatric-type dissecting aneurysms may be different from adult-type dissecting aneurysms, a dissecting aneurysm cannot be ruled out. At first, coil embolization was considered for the persistent rupture, and coiling was performed on the true aneurysmal wall and pseudoaneurysm sac. However, anterograde ACA perfusion was undesirable due to intravascular space thrombus formation and high intracranial pressure in the serial angiogram, and coil instability was also accompanied, so endovascular trapping was planned. Because there was a perforator around the anterior communicating artery (ACoA) and it was thought to be good to maintain embryologic circulation, complete trapping was performed while preserving the orbitofrontal artery (Fig. 2). Total occlusion of aneurysm was achieved and there was no post-procedural thromboembolism. Postprocedural angiogram showed minimal leptomeningeal collaterals (Fig. 2C).

The patient admitted to pediatric intensive care unit. There was no improvement of neurologic status after coil embolization. At follow-up brain CT, diffuse cerebral edema with left uncal herniation and decreased grey-white matter differentiation was observed, diffuse hypoxic brain damage was suspected. Non-convulsive status epilepticus was excluded by portable electroencephalography which showed diffuse cerebral dysfunction. At postoperative day (POD) 3, transcranial doppler (TCD) ultrasound was performed and biphasic waveform was detected which means cerebral circulatory arrest. Poor prognosis was informed to parents and they decided not to perform further major operation, but wanted to maintain all medical treatment. At POD 53, chronic subdural hematoma with 4 cm-thickness was detected incidentally in brain CT and it was resolved after burr hole trephination and drainage. Inotropic agent was tapered off but need for respiratory support was sustained, so tracheostomy was performed at POD 65. With best medical care including pituitary hormone replacement, the patient transferred to general ward at POD 128 and discharged to home with portable ventilator at POD 337.