The photo, taken April 19, shows Kirk talking with visiting staff members at the center.
The 52-year-old Republican was in good health when he had a stroke last month.
Neurosurgeon Richard Fessler says Kirk is alert, talking and responding well to questions.
Doctors say he’s making progress, but recovery will be a long process
The neurosurgeon who operated on Mark Kirk after his stroke says he is progressing as expected but remains in serious condition.
Kirk’s colleagues are likely to lend a hand, as they have for others who were absent for long periods.
It’s unclear how long his recovery could take or whether his full movement would be restored, doctors said.