My husband has MSA-P and has the same hiccup issue. One time they lasted continuously for several days. He was exhausted and we tried everything to stop them. The meds that would normally stop them also lower blood pressure and his is already low so we couldn’t chance it. His neurologist tried him on Gabapentin and it stopped them! This is not normally used for hiccups but he thought it was worth trying and it worked! He did not stay on it but we might discuss it at the next visit since he is embarrassed and doesn’t want to go out.