From ESPN:

Sabres forward Kyle Okposo has spent the past three days in a Buffalo hospital undergoing a battery of tests to determine an undisclosed illness that has sidelined him for more than a week, according to multiple reports.

Buffalo's WGR-Radio first reported that Okposo was in the neurosurgical intensive care unit at Buffalo General Hospital earlier Wednesday before the Sabres played their home finale against the Montreal Canadiens.

"Kyle continues to be under the care of our doctors as he deals with symptoms from an illness," the Sabres said in a statement Wednesday night. "Out of respect to Kyle and his family, we will have no further comment at this time."