Can heat stroke cause stroke-like damage?

My mom had an episode in August that she describes as heat stroke and dehydration. She had been exposed to warm weather and hadn't had much to drink. That night, for a couple hours she was overheated and couldn't get her body to cool down until she used cold, wet wash cloths on her head and upper body to finally cool herself off. Others in the house were comfortably sleeping under their covers, so the house wasn't overly warm. She didn't go to the hospital and didn't wake up her friends for help. The next day she was extremely tired and weak, and had a terrible migraine - she attributed that to the dehydration. Within a couple days she was experiencing marked right side weakness & slurred speech and now also has swallowing issues. Could the possible heat stroke have caused brain damage to the extent that it could cause this kind of neurological damage and decline? She's had cat scans, an MRA and a neurologist did an EMG - all were normal. They are sending her to another neurologist at Virginia Mason in Seattle (in January) to see if they can find anything. Could this possibly have been caused by the heat stroke? The docs say she didn't have a stroke due to no indication on cat scans or the MRA, but those tests weren't done for a few weeks after the August episode. She also started noticing some weakness in her right hand in June, but the major problems started in August after the heat stroke episode and they happened pretty quickly after that. Thank you for any information you can provide.