"Brooke is in the hospital ICU related to the surgery for her impacted wisdom tooth," her lawyer Yale Galanter tells PEOPLE. "They are trying to get the infection and fever under control. The infection has spread."
Mueller, 32, and husband Charlie Sheen, 44, are due to attend a hearing in the Aspen court, where she is seeking to modify the protective order put into place after Sheen's domestic-violence arrest on Christmas day.
Sheen, whose interaction with Mueller is limited by the constraints of the protective order, was nonetheless seen visiting Mueller in the ICU, reports TMZ.com.
"Mueller wants to be able to communicate with her husband and hopes they can go back together as a family with their 9-month-old twins, Bob and Max," Galanter tells PEOPLE.
The hearing has been postponed several times due to the judge's schedule and now Mueller's illness.