"...[In a 1991] medical study of 84 persistent vegetative state (PVS) patients, over 52% of the patients recovered within one year. After three years, 58% had regained consciousness. After extensive review of the data, researchers were unable to identify any reliable way to predict who might recover and who might not. In other words, every PVS patient has a chance of recovery."
~ Levin, "Vegetative State After Closed-Head Injury", 48 Archives of Neurology, 580-585 (June 1991) cited in LIFE AT RISK, 1:( 6) Dec. 1991.
Dec. 1991. About one year after Terri collapsed.
Thanks to reader Steve who pointed out the above link was broken....now fixed!