Sir—DK Menon and colleagues’ report (July 18, p 200) 1 on cortical processing in persistent vegetative state could lead to confusion in the discussions on withholding or withdrawing treatment from patients in permanent vegetative state. For three reasons this report should not be considered in these discussions. First, these discussions deal with patients in the permanent vegetative state, which is different from the persistent vegetative state. Jennett and Plum2 defined persistent as sustained over time and permanent as irreversible. Persistent vegetative state is a diagnosis; permanent vegetative state is a prognosis. 3 To avoid confusion between the terms persistent and permanent the Multi-Society Task