Use of Cranial Trephines and Central Probes in Rodents
Generally, the opening of a body cavity entails major surgery. Exceptions include penetration of a body cavity for purposes of injections of pharmacological agents, such as anesthetics. Surgical interventions on the brain, such as aspirations or lobotomies also constitute major surgical manipulations. However, in keeping with policies for other body cavities the mere introduction of a cannula or probe into the cranial vault may be considered a procedure, as long as the technique itself does not result in significant neural damage or incapacitation. Although a trephine hole may need to be established to accomplish the introduction of experimental devices, it is the meninges that represent the real boundary of the brain. In parallel with the policies for other body cavities, the introduction of a passive probe or a device for delivering pharmacological or physiologically-active agents into the central nervous system should be considered a procedure as long as the technique itself does not compromise brain function. If subsequent manipulations via the probe, cannula, or other device lead to pain or distress, they would be subject to the general policies relating to such conditions.
