no it doesn't; I've read numerous studies on the subject, and of the big three NMDA antagonists (DXM, Ketamine, and PCP), DXM is the least likely to result in Olney's Lesions;

The study I read also said that taking smaller doses of DXM in the 200-600mg range, even numerous times, was very unlikely to cause any sort of damage, and only massive 1,000mg+ doses would put a person at risk for brain damage