The Feb. 2 episode of the NBC medical drama is devoted to Woods' character, Dr. Nate Lennox, and his battle with the debilitating neurodegenerative disease, the ALS Association said in a news release Monday.
Nearly 30,000 U.S. residents currently have ALS, for which there is no cure.
To help prepare for the role, Woods, "ER" director Paul McCrane and writer Joel Sachs met on the set with six people with ALS, who described their experiences with the disease as well as their outlook on life.
The episode has Lennox in a very advanced stage of ALS and shows its progression through a series of flashbacks dating to 1999, the association said.
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