ABSTRACT
Prognostic nerve blocks are used to predict outcome. These blocks help the patient and the physician decide whether to proceed with surgery or nerve destruction procedures. Diagnostic and prognostic blocks require precise localization of nerve to be of value. Inaccurate needle positioning results in overoptimistic interpretation of the results of definitive treatment. There are several problems associated with the interpretation of results:
• A placebo response. • Local anaesthetic spreads to adjacent nerves. • The patient responds to the systemic action of local anaesthetic. • The nerve block includes the sympathetic nerve fibres and the block is not
specific.
