What is one complication of spinal cord injuries at a lesion above T1?

A spinal cord injury at a lesion above the T1 level can significantly impact sympathetic nervous system function, particularly in the regulation of heart rate. The sympathetic pathways that control the heart originate from the thoracic segments of the spinal cord, specifically T1 to T4. When the injury is above this level, the output from the sympathetic nervous system to the heart is disrupted.

This disruption results in decreased sympathetic innervation to the heart, leading to a diminished ability to respond effectively to physiological stressors. As a result, the heart may not receive adequate stimulation to increase heart rate during situations that typically demand such a response, such as exercise or stress. This lack of sympathetic activation can lead to bradycardia (a slower than normal heart rate) and impaired cardiovascular responses.

In contrast, the other options suggest scenarios that do not align with the physiological consequences of such an injury. The heart does not receive sympathetic stimulation, resulting in the correct understanding that there is no sympathetic innervation, which is crucial for proper cardiovascular function.