Direct measurement of intracranial pressure in adult horses

Objective. To develop a method for surgical placement of a commercial microsensor intracranial pressure (ICP) transducer and to characterize normal ICP and cerebral perfusion pressures (CPP) in conscious adult horses. Animals. 6 healthy castrated male adult horses (1 Holsteiner, 1 Quarter Horse, and 4 Thoroughbreds). Procedure. Anesthesia was induced and maintained by use of isoflurane as the sole agent. Catheters were inserted percutaneously into the jugular vein and carotid artery. A microsensor ICP transducer was inserted in the subarachnoid space by means of right parietal craniotomy. The burr hole was then sealed with bone wax, the surgical incision was sutured, and the transducer was secured in place. Measurements were collected 1 hour after horses were able to stand during recovery from anesthesia. Result. Mean ± SD values for ICP and CPP were 2 ± 4 and 102 ± 26 mm Hg, respectively. Conclusions and Clinical Relevance. This report describes a relatively facile technique for obtaining direct and accurate ICP measurements for adult horses. The ICP values obtained in this study are within reference ranges established for other species and provide a point of reference for the diagnosis of abnormal ICP in adult horses.