This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S, Subject name: Medicine
[{'content': 'Lateral medullary syndrome is associated with \nSelect and explain. \nA. Dissociative anaesthesia, B. Dense hemianaesthesia, C. Crossed hemianesthesia, D. No sensory defect', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Lateral medullary syndrome is a neurological disorder causing a range of symptoms due to ischemia in the lateral pa of the medulla oblongata in the brainstem. The ischemia is a result of a blockage most commonly in the veebral aery or the posterior inferior cerebellar aery Ref Harrison20th edition pg 2334', 'role': 'assistant'}]