We report an unusual case of lateral medullary infarction after successful embolization of the vertebral artery dissecting aneurysm (VADA). A 49-year-old man who had no noteworthy previous medical history was admitted to our hospital with a severe headache. Computed tomography (CT) revealed a subarachnoid hemorrhage, located in the basal cistern and posterior fossa. Cerebral angiography showed a VADA, that did not involve the origin of the posterior inferior cerebellar artery (PICA). We treated this aneurysm via endovascular trapping of the vertebral artery distal to the PICA. After operation, CT revealed post-hemorrhagic hydrocephalus, which we resolved with a permanent ventriculoperitoneal shunt procedure. Postoperatively, the patient experienced transient mild hoarsness and dysphagia. Magnetic resonance image (MRI) showed a small infarction in the right side of the medulla. The patient recovered well, though he still had some residual symptom of dysphagia at discharge. Such an event is uncommon but can be a major clinical concern. Further investigation to reveal risk factors and/or causative mechanisms for the medullary infarction after successful endovascular trapping of the VADA are sorely needed, to minimize such a complication.