Benign outcome of objectively proven spontaneous recanalization of internal carotid artery occlusion

Objective Spontaneous recanalization of intracranial internal carotid artery (ICA) occlusion is frequent in embolic strokes. Spontaneous recanalization of the extracranial portion of the ICA occlusion of atherosclerotic or embolic origin is only anecdotally reported, and data are lacking about its incidence, natural history, and outcome in long-term follow-up. Methods Consecutive patients with ICA occlusion were prospectively identified and followed-up to detect the incidence of a spontaneous recanalization. Patients with objectively confirmed recanalization were prospectively followed-up to observe their natural history and the onset of new cerebrovascular events. ICA occlusion and spontaneous recanalization were diagnosed by means of color-coded Doppler ultrasound imaging or selective contrast angiography, or both. All patients were evaluated and treated for atherosclerotic risk factors. Results Spontaneous recanalization occurred in 16 of 696 patients (2.3%; 95% confidence interval, 1.3%-3.7%) with ICA occlusion after a mean interval of 38 months from the diagnosis of occlusion. Spontaneous recanalization was detected with color-coded Doppler ultrasound imaging and with selective contrast angiography, with a complete agreement of diagnostic findings. Two patients presented with symptomatic spontaneous recanalization. All patients with spontaneous recanalization were asymptomatic after a mean follow-up of 66.2 months. Conclusions Spontaneous recanalization of previously occluded extracranial ICAs is more frequent than anticipated. Once it occurs, spontaneous recanalization seems to have a benign long-term course.