Cerebral blood flow measurement has not yet been attempted with xenon and CT in patients. Xenon washout was studied in three patients receiving subanesthetic concentrations of xenon. Cerebral enhancement after 30%--50% inhaled xenon was demonstrated without serious side effects. Clinical cerebral blood flow measurements with xenon and CT may be feasible.

Epidemiological data and clinical indicia reveal devastating consequences associated with pediatric neck injuries. Unfortunately, neither injury prevention nor clinical management strategies will be able to effectively reduce these injuries or their effects on children, without an understanding of the cervical spine developmental biomechanics. Thus, we investigated the relationship between spinal development and the functional (stiffness) and failure biomechanical characteristics of the cervical spine in a baboon model. A correlation study design was used to define the relationships between spinal tissue maturation and spinal biomechanics in both tension and compression. Eighteen baboon cervical spine specimens distributed across the developmental spectrum (1–26 human equivalent years) were dissected into osteoligamentous functional spinal units. Using a servo-hydraulic MTS, these specimens (Oc–C2, C3–C4, C5–C6, C7–T1) were non-destructively tested in tension and compression and then displaced to failure in tension while measuring the six-axes of loads and displacements. The functions describing the developmental biomechanical response of the cervical spine for stiffness and normalized stiffness exhibited a significant direct relationship in both tension and compression loading. Similarly, the tensile failure load and normalized failure load demonstrated significant maturational increases. Further, differences in biomechanical response were observed between the spinal levels examined and all levels exhibited clinically relevant failure patterns. These data support our understanding of the child cervical spine from a developmental biomechanics perspective and facilitate the development of injury prevention or management schema for the mitigation of child spine injuries and their deleterious effects.

Compression studies were conducted on the ligamentous thoracolumbar spines of fresh human male cadavers. For comparison, forces were applied to the posterior upper thoracic region of intact seated cadavers. Since thoracolumbar flexion injury routinely involves ligament failure and vertebral body wedge compression fractures, studies were conducted on single vertebral bodies and isolated ligaments. Similar studies were conducted in isolated monkey ligaments. The intact and ligamentous thoracolumbar spines failed predominantly in the region of the thoracolumbar junction at forces from 1113-5110 N. For both the human and monkey cadavers, the anterior longitudinal ligament was the strongest. The human ligaments were 2-5 times stronger than those of the monkey. For the covering abstract of the conference see HS-036 716. (Author/TRRL)

: Axial forces were applied between the shoulders and skull of eight male Macaca mulatta monkeys. Forces from 556 to 1444 Newtons produced marked changes in blood pressure, heart rate and distraction of the cervical spinal column with minimal ligamentous disruption. Somatosensory evoked potentials recorded at the cortical and thalamic levels following dorsal column or peripheral nerve stimulation were altered prior to or during changes in heart rate or blood pressure. Similar findings were observed in the efferent responses recorded from electrodes placed on the thoracic spinal cord following stimulation of sensorimotor cortex. Studies in four monkey cadaveric isolated cervical column preparations indicate that disruption occurs with axial loads which are approximately one-third of the maximum used in the in vivo studies.