Final answer:
The addition of 1 MAC of isoflurane typically causes decreased amplitude and increased latency in the cortical component of somatosensory evoked potentials, indicating a depressive effect on the central nervous system's electrical activity.
Step-by-step explanation:
The addition of 1 MAC of isoflurane to a 15-year-old, 55-kg patient with scoliosis undergoing general anesthesia for a posterior spinal fusion will result in decreased amplitude and increased latency of the cortical component of somatosensory evoked potentials. Isoflurane and other volatile anesthetics are known to depress the central nervous system, which leads to a reduction in electrical activity as measured by amplitude, and can slow down the speed of nerve conduction, thereby increasing the time it takes signals to reach the cortex as measured by latency.
In a separate clinical context, after a motorcycle accident resulting in a thoracic spinal cord hemisection, the victim would experience specific sensory deficits. Sensory discrimination helps determine the location and severity of the damage. In this case, the victim would likely be able to perceive pain on the side of the body with the hemisection and below the level of injury, but may lose fine touch sensation due to the damage. On the contralateral side, these sensations would be preserved because the pain fibers cross the midline and ascend in the lateral column of the spinal cord, while the dorsal column, responsible for fine touch, remains intact on the side opposite the hemisection.