impaired thermoregulation
/ THUR-moh-reg-yoo-LAY-shun /
Your body keeps itself near a steady temperature using a clever toolkit: it sweats and flushes the skin to dump heat when hot, and shivers and tightens skin blood vessels to hold heat when cold. The brain runs this system through nerves that travel down the spinal cord to reach the skin all over the body. After a spinal cord injury, especially a high one, the brain loses its line to the skin below the level — so the body can no longer sweat, shiver, or adjust blood flow there on command. The result is impaired thermoregulation, a body that tends to drift toward the temperature of its surroundings.
Below the level of injury the person cannot sweat to cool down, cannot shiver to warm up, and cannot redirect blood flow to conserve or shed heat — the skin in that region is, in effect, off the thermostat's grid. In a hot environment, heat builds up unchecked and body temperature can climb dangerously (hyperthermia); in a cold one, heat leaks away and the person can chill too far (hypothermia). Higher injuries lose a larger area of skin from the system, so high tetraplegia is most affected. Confusingly, the loss of sympathetic control can also produce odd episodes of sweating, and people may not feel the warning sensations of being too hot or too cold below the level. Because the body partly follows the environment, this is sometimes loosely called being 'poikilothermic'.
This matters in everyday rehabilitation and life because environments that healthy people shrug off can become hazardous. A hot summer day, a sweltering gym, a hot bath, or a heavy exercise session can overheat someone who cannot sweat; a cold room or winter outing can chill them. Management is mostly behavioural and environmental: dressing in layers that can be adjusted, controlling room temperature, using external cooling (cool drinks, fans, damp cloths, shade) or external warming as needed, hydrating, and pacing activity in the heat. It is a quiet but real safety issue that people and caregivers must learn to manage actively.
On a hot day, a woman with a C5 injury cannot sweat below her neck, so heat builds up and she starts to feel unwell without realising she is overheating. Her aide moves her into the shade, gives her cool drinks, and wipes her skin with a damp cloth, bringing her temperature back down.
Below the injury the skin is off the thermostat's grid, so the body drifts toward the room's temperature.
Because warning sensations are blunted below the level, a person may be dangerously overheated or chilled without feeling it. Management is mostly environmental — controlling the surroundings rather than relying on the body to compensate — and the risk is greatest in high injuries with the most skin disconnected.