When Capt. James Deakins first appeared in the precinct with his face partly contorted and one eye covered with a large black patch on the May 1 episode of NBC's Law & Order: Criminal Intent, his ailment—Bell's palsy—was explained in two throwaway lines. But for Jamey Sheridan, 53, the actor who plays Deakins, it was a struggle just to say his line. In March Sheridan was diagnosed with the rare facial nerve disorder (see box) that causes one side of the face to be paralyzed. His left eye was frozen open—hence the need for a protective patch—and speaking took all his energy. Undaunted, the L.A.-based actor commuted as usual to the show's New York City set, where Criminal Intent's writers incorporated his condition into the script. Now fully recovered, Sheridan recounts his ordeal to PEOPLE's Mark Dagostino.

I had a sinus infection through the winter. My three kids went through it, my wife [actress Colette Kilroy] had had it. But it got really bad the Saturday before Easter, so I was given an antibiotic. By Monday night the left side of my face was paralyzed. I thought it was the antibiotic working on the infection. But when I looked in the mirror the next morning, I went, "Yeow! Who's that?" My face appeared to have melted. The whole forehead was hanging halfway down over my eye. Gradually, over the first day, the eye froze open. Half your lips don't move. Half your tongue! I could taste on one side, not the other.

I called my doctor, and on Wednesday I went to St. John's Health Center in L.A. and got an MRI to rule out any brain-related problems. No cancer, no stroke, no tumor. There's no test, however, for Bell's palsy that says, "This is it." Instead, it's like a bucket into which doctors throw every symptom that they can't explain. The cause isn't clear either. I was told that neither the sinus infection nor some dentistry I had earlier in the winter had anything to do with it. At the hospital they told me, "This happens, and it goes away."

At first I think I was in denial. I kept laughing and cracking jokes about it. I just didn't want to face it at all. But then I started worrying, "What the hell am I going to do about Criminal Intent? I'm supposed to shoot it next week."

After talking to the show's producers, Sheridan went back to work in New York.

Walking around, I try to be friendly when people stop me, but now there were looks that were like, "Oh, that poor guy." People are thinking, "Did he get burned? Is he paralyzed?" Pity.

The first day back on the set, everybody was nice to me. Katy [costar Kathryn Erbe] promised me she was going to say "Aye, aye!" on film, but she chickened out. Mostly it was like, "Are you all right?" And "Thanks for coming and thanks for working." I was thinking on a whole other level, like, "This could be the last job I ever have."

Filming the show, I had to find a way to enunciate. That's all I did: put all my energy into getting the words out. And with my eye patch, depth perception is minimized. If I'm going to see someone in the chair next to me, I have to turn my head all the way.

It was probably 2½ weeks later when I began taking cortisone injections. My doctor then increased the antiviral dosage. That's when I started really improving. After 3½ weeks I was able to remove the patch. I was able to blink again. And now the facial sag is gone.

You think you're kind of unstoppable, you know? And then you find out that you're really quite vulnerable. Getting out of the subway today, everyone was complaining because a guy at the top of the stairs was moving real slow. I looked up. He was nearly a quadriplegic. Instead of going around him, I stayed behind him all the way up the stairs. We could all get laid low like that at any time. I want to remember what that feels like.