Unlike high-grade stenosis, dissections of craniocervical arteries are a rare cause of cerebrovascular infarction. If the internal carotid artery (ICA) dissection is verified by duplex scanning or computed tomography angiography (CTA), the therapies of choice are antiplatelet and anticoagulation drugs, and surgical treatment is rarely performed. However, despite distinct clinical and radiological manifestation, carotid dissections are still under-recognized. In this study, we demonstrate the case of a 66-year-old man with dissection of ICA verified by duplex scanning and computed tomography angiography. The cause of missed diagnosis was an ascending pharyngeal artery originating from the ICA that runs parallel to it. Other than being a rare variation, this case may be interesting as a cause of misdiagnosis.