orthostatic hypotension in SCI
/ or-thoh-STAT-ik HY-poh-TEN-shun /
Stand up too fast and most people feel a brief lightheaded swoon before their body catches up. Normally the nervous system reacts in a heartbeat: it squeezes the leg and belly blood vessels so gravity does not pool blood in the lower body, keeping the brain supplied. After a spinal cord injury, especially a high one, that automatic squeeze can fail — so sitting or standing up makes blood drain downward and blood pressure crashes. That crash, brought on by changing position, is orthostatic hypotension.
The reason is that the sympathetic nerves that tighten blood vessels leave the cord in the chest region; an injury above them cuts the brain's control over this reflex. When the person is tilted upright, blood pools in the legs and abdomen, less returns to the heart, blood pressure drops, and the brain is briefly underfed — causing dizziness, blurred vision, ringing ears, a grey-out, sometimes fainting, and in some people a vague nausea or fatigue. It is most troublesome in the early weeks after injury and tends to ease over time as the body adapts, though it can persist. Practical management is unglamorous but effective: rising slowly and in stages, compression stockings and an abdominal binder to discourage pooling, good hydration, and gradually re-training tolerance to the upright position (often on a tilt table).
Orthostatic hypotension matters in rehabilitation because it can stall the whole programme. A person who faints or greys out every time they sit up cannot tolerate the sitting, standing, and transfer training that recovery depends on. It is the mirror image of autonomic dysreflexia — here blood pressure is too low instead of dangerously high — and the two can even coexist in the same person. Managing it well is often the quiet prerequisite for getting therapy moving at all.
Each morning a woman with a C7 injury feels grey and dizzy the moment her bed is raised. The team puts compression stockings and an abdominal binder on her, raises her in slow stages on a tilt table, and over a couple of weeks her body relearns to hold its blood pressure upright, letting full therapy begin.
Without sympathetic control, sitting up lets blood pool downward and pressure crash — managed by slow tilting, stockings, and a binder.
Orthostatic hypotension and autonomic dysreflexia are opposite blood-pressure problems and can occur in the same high-level patient, so the response must match the situation: lay the person flat for low-pressure faintness, but sit them upright for the dangerously high pressure of dysreflexia.