Fusiform Aneurysm on the Basilar Artery Trunk Treated with Intra-Aneurysmal Embolization with Parent Vessel Occlusion after Complete Preoperative Occlusion Test
An 18-year-old female suffered a headache for 2 weeks. Computed tomography and magnetic resonance image revealed a fusiform aneurysm on the lower BA trunk. Digital subtraction angiography (DSA) revealed a 7.1×11.0 mm-sized fusiform aneurysm located just below the anterior inferior cerebellar artery (AICA) (). Right side posterior inferior cerebellar artery was not seen. Both posterior cerebral arteries (PCA) and superior cerebellar arteries (SCA) filled normally. Both posterior communicating arteries (PComA) were patent and the diameter of both arteries was more than 1 mm in diameter (). For the proximal portion of the aneurysm forming a severe acute angle, flow diversion with multiple stent is difficult to enforce. Endovascular coiling of aneurysm with occlusion of dysplastic parent vessel is planned if the patient tolerate complete preoperative occlusion test.\nThe location of aneurysm is just distal to vertebrobasilar junction and proximal to the origin of AICA, and it is somewhat related perforating artery injury to perform a BTO at basilar artery. We planned the BTO on both vertebral arteries. BTO was performed under local anesthesia and accessible for neurological examination. At the time of the BTO, the neurological status of the patient was continuously monitored by a trained neurosurgeon that assessed speech, motor strength, sensory extinction, and level of alertness ().\nBilateral femoral artery (FA) punctures were performed and guide catheter placed in both vertebral arteries (VA). Additional right FA puncture was performed for diagnostic cerebral angiogram. The patient was anticoagulated by the intravenous injection of 5000 IU heparin. Over-the-wire microballoon (Hyperfrom, Hyperglide; ev3, Irvine, CA, USA) was used for BTO and these balloons were located at VA just around the C2 vertebra foramen (). The balloon was then inflated. Complete balloon occlusion of VA was verified by a proximal contrast injection. The BA and both AICAs were visible through the retrograde blood flow from the PComA, which were visualized by an angiographic injection in the both internal carotid artery (ICA).\nBilateral BTO of the each VA were performed over 20 min under a normotensive state. Baseline blood pressure was 109/72 mm Hg (mean arterial blood pressure, 84.33 mm Hg). The patient tolerated 20 minutes under the normotensive state and hypotension was induced pharmacologically by the intravenous infusion of nicardipine (starting dose of 5 mg/hr with 2.5 mg/hr increase every 5 min if the blood pressure did not reach the target range). After the mean arterial pressure was reduced by 20% of baseline (92/56 mm Hg; mean arterial blood pressure, 68.0 mm Hg), hypotension was maintained for 20 minutes.\nBefore BTO, the patient underwent a complete TCD investigation. The patient-customized TCD headset was mounted. BTO was performed with concomitant monitoring of the blood velocity and direction of the blood flow in the middle cerebral artery (MCA) and P1 segment of the PCA.\nBaseline Tc-99m hexamethylpropylenamineoxime (Tc-99m HMPAO) qualitative SPECT was performed one day prior to the BTO. Another SPECT after BTO also checked. Tc-99m HMPAO was injected intravenously approximately 10 min after the balloon was inflated.\nBaseline neurophysiologic monitoring steps included electroencephalography, somatosensory evoked potential, and brain stem auditory evoked potential. During the BTO, NPMs was closely observed.\nDSA during BTO, the right ICA angiogram showed retrograde filling of the distal part of the BA, PCAs, SCAs and AICASs through the PComA (). The patient tolerated 20 minutes under the normotensive state and induced hypotensive state with no developing neurological deficits.\nBaseline mean blood flow velocity of MCA was 74 cm/s (). The velocity during BTO dropped immediately to 48 cm/s upon balloon inflation, but returned to the baseline value (72 cm/s) within several seconds without additional treatment and was maintained during the BTO. After induced hypotension, it dropped to 65 cm/s; the patient tolerated in induced hypotensive condition. After deflation of the balloon, the velocity of the MCA recovered to the baseline value. The reduction of flow velocity was 2.7% under the normotensive state and 12.2% under induced hypotensive state.\nBaseline SPECT images did not show any focal perfusion reduction (). SPECT images obtained after BTO also did not showed hypoperfusion of the cerebral hemisphere and cerebellum compare to the baseline SPECT.\nDuring the BTO, there is no NPMs change in this patient.\nCoil embolization was performed with multiple coils in the usual way. Care was taken to preserve the both AICAs, which arose close to the distal aspect of the aneurysm. After coil embolization, a left side ICA angiogram () showed regrograde filling of the BA (arrow) and both AICAs (arrowhead) through the PComA. A right side VA angiogram showed complete obliteration of the aneurysm and no filling of the BA though the VA.\nThe patient was discharged without any neurological symptoms. After 6 months after treatment, the patient was doing well without any focal neurological deficits.