The statement was posted to Facebook along with a photo of Wrightson in his hospital bed. It said that while he is in generally good health and able to sign his name (so signed prints and the occasional piece of signed art from their current inventory will likely be made available in the future), they did not foresee Wrightson recovering sufficiently to create new art or attend conventions.
You can check out the full statement in the embed above.
For those who struggle with the Facebook embed, the short version is that Wrightson was falling and having problems with his perception last November. He was hospitalized and after the latest in a series of brain surgeries, the artist has "extremely limited function" on his left side, and cannot walk or reliably use his left hand.
Wrightson came to comics in 1968 and is best known for his work on horror titles like House of Secrets and Weird Mystery Tales. He also collaborated with Thanos creator and Batman writer Jim Starlin in the '80s on projects like Heroes For Hope (a charity project to aid African famine relief), Batman: The Cult, and The Weird.
Another frequent collaborator with Wrightson was best-selling author Stephen King. In 1983, Wrightson illustrated the comic book adaptation of the King-penned horror film Creepshow. He would later provide illustrations for the novella Cycle of the Werewolf, the restored edition of King's novel The Stand, and Wolves of the Calla, the fifth installment of King's Dark Tower series.
He also worked in Hollywood, providing art for the Heavy Metal movie and Serenity.
Wrightson's last major work was the IDW series Frankenstein Alive, Alive!, a sequel to Wrightson's decades-old Bernie Wrightson's Frankenstein. In 2013, Wrightson was awarded a National Cartoonists Association award for the work.