Effect of hyperextension-hyperflexion (whiplash) on the function of the blood-brain barrier of rhesus monkeys

Fifteen rhesus monkeys were placed in a cart and subjected to a sudden acceleration to administer a whiplash. The intensity of the acceleration of the head was determined either with a high-speed movie or from accelerometers mounted on the skull. The cart was maximally accelerated at 35 g 30 ms after onset of the impact, and the maximal angular acceleration was 40 × 10 3 rad/s 2 at 50 ms. The animals did not apparently lose consciousness. The permeability of the blood-brain barrier (BBB) was assessed prior to and 1 h after the whiplash trauma using intravenously administered radioactive pertechnetate ( 99mTc). The ratio of radioactivity in the cerebrospinal fluid to that in the blood 1 h after administration served as a measure of the blood-brain barrier permeability. Prior to the whiplash trauma this ratio was 4.85 × 10 −3, and after the trauma it had increased to 28.44 × 10 −3. This acute change in barrier function may contribute to the alterations in function of the central nervous system subsequent to whiplash trauma.