From wikipedia:

He underwent further surgery on June 16, 2006, just two days before his 64th birthday, to remove cancer near his right jaw, which included removing a section of jaw bone.

On July 1, Ebert was hospitalized in serious condition after his carotid artery burst near the surgery site and he "came within a breath of death". He later learned that the burst was likely a side effect of his treatment, which involved neutron beam radiation. He was subsequently kept bedridden to prevent further damage to the scarred vessels in his neck while he slowly recovered from multiple surgeries and the rigorous treatment. At one point, his status was so precarious that Ebert had a tracheostomy done on his neck to reduce the effort of breathing while he recovered.

In a July 21, 2007 commentary on a rebuttal to Clive Barker, he revealed that he had lost the ability to speak, but not to write. Currently, he talks using a computerized voice system. He initially chose to use a voice with a British accent that he named "Lawrence", but eventually began using one with an American accent.