Yep, and you're more likely than not to find ER folks who've never heard of TN.

Here are guidelines from the TNA for ER visits during severe attacks -

Emergency Room Management of Episodes of Severe TN

Yes, it's always a good idea to have a letter from you doctor. If the ER is in a big enough hospital, you should ask for the neurologist on call as well.

Good luck and I hope you never have to use the letter, but best to have it and a plan. Talk over with your neuro what would be best to treat you with in that situation.

Jean