Updated

It was six months ago that the University of Wisconsin Hospital in Madison notified some surgery patients they may have been exposed to contaminated instruments.

The exposure left the patients with a low risk of contracting a deadly brain disorder. The hospital says as of mid-December, none of the 53 patients reported any symptoms of the disorder.

The surgical tools were used on a woman who died of Creutzfeldt-Jakob disease. The other patients had surgery when the instruments were still in use.

Hospital spokeswoman Lisa Brunette says the patients were told to report symptoms of CJD, including problems with walking or vision. She tells the Wisconsin State Journal the patients faced an "infinitesimal" chance of contracting it.