Multidetector Computed Tomographic Angiography in Horner Syndrome

A 62-year-old man presented with Horner syndrome secondary to an internal carotid artery dissecting aneurysm detected by multi-detector computed tomographic angiography (MDCTA). Follow-up imaging failed to demonstrate any significant reduction in the size of the aneurysm despite resolution of clinical signs, suggesting that localized inflammation may play an important aetiological role. The size of aneurysm required to cause Horner syndrome has not been fully elucidated, but is important as it determines the likelihood of detection. We report a case in which MDCTA successfully visualized a small, clinically significant dissecting aneurysm causing Horner syndrome.