Cognitive Outcome and Clinically Silent Thromboembolic Events After Coiling of Asymptomatic Unruptured Intracranial Aneurysms

BACKGROUND: Thromboembolic events are the most common complication after coiling of unruptured intracranial aneurysms (UIAs). However, it remains unclear whether these clinically silent ischemic lesions (CSILs) have any clinical significance. OBJECTIVE: To evaluate cognitive outcome after coil embolization of asymptomatic UIAs and its relationship with CSILs after the procedure. METHODS: We prospectively enrolled 40 UIA patients who showed no new focal neurological deficit after coil embolization. CSILs were assessed with diffusion-weighted imaging (DWI) within 1 day after the procedure. A battery of neuropsychological tests was performed 3 times: preoperatively and postoperatively at 1 and 4 weeks after coil embolization. RESULTS: The incidence of cognitive impairment after coiling in patients with UIAs was 44% (17 of 39) at 1 week and 19% (7 of 37) at 4 weeks after coil embolization. DWI within 1 day after coil embolization revealed that 60% of patients (24 of 40) showed CSILs. However, no significant difference was found in any mean cognitive scores or in the number of cognitively impaired variables between patients with and without CSILs at weeks 1 and 4. Additional correlation analysis revealed no correlations between the number of CSILs on DWI and the cognitive sum z score at both 1 and 4 weeks. CONCLUSION: Exhaustive neuropsychological evaluation of UIA patients who underwent coil embolization demonstrated recovery or improvements from baseline cognitive function after 4 weeks, although some patients still showed cognitive deficits at 4 weeks after the procedure. However, we found no statistically significant relationship between the presence and number of CSILs on DWI and cognitive changes after the procedure.