George Blaney, the team's associate head coach, will take Calhoun's place on the sidelines.
The 69-year-old Calhoun has not commented on the situation, but in a release Calhoun's doctor Peter Schulman said:
Last summer, Jim had some significant back pain and has seen two excellent back specialists. The initial approach recommended to him was stretching, physical therapy and exercise, and that was successful for several months. It turns out that there is some degenerative problem in the lumbar vertebrae and it’s impinging on the nerves. It has led to significant back pain and some symptoms in his lower extremities. Jim has been able to manage it with the physical therapy and stretching, but over the last several days, things have become worse and he is not able to deal with this on a day to day basis, so other options need to be considered. Right now, he is physically unable to coach.
This is the third time Calhoun has taken a medical leave as Huskies' coach. In 2003 he missed 16 days after having surgery to treat prostate cancer, and in 2010 he missed just less than a month with undisclosed health issues.
The first game Calhoun will miss is Saturday's tilt with Seton Hall.
Calhoun has had an incredibly successful career, which includes three National Championships. The most recent of which was last season, when he led the Huskies on an improbable run through the Big East Tournament and then the NCAA Tournament.