Placebo-controlled procedural trials for neurological conditions.

Neurological disease has been a central focus in the ongoing ethical debate over the use of invasive placebo controls, especially sham surgery. The risk to research subjects and necessary use of deception involved in these procedures must be balanced against the methodological need to control for bias and the placebo effect. We review a framework formulated for the ethical assessment of sham surgery in the context of research evaluating novel procedures for neurological conditions. Special issues raised include the growing evidence of expectation and conditioning effects in a number of neurological diseases, the escalating scale of risk from different types of invasive placebo interventions, and the increasing use of cross-over designs, which allow a switch from placebo to active intervention without additional procedures.