Situation: A 30-year-old man with a complete spinal cord injury at the sixth cervical (C6) level from a fall 3 months ago is on a rehabilitation unit. Spinal shock has resolved. His bladder is emptied by intermittent catheterization every 4 hours. His usual blood pressure (BP) is 96/60 mmHg. At 14:00, 30 minutes before his next catheterization, he reports a pounding headache and blurred vision. His face and neck are flushed and sweaty. BP is 150/92 mmHg and heart rate is 54/min. Which is the MOST likely explanation?

In cord injury at T6 or above, a noxious stimulus below the level, most often a full bladder, triggers a massive sympathetic discharge. A systolic rise of 20 to 40 mmHg or more above baseline is significant, and his 150 mmHg is 54 mmHg above his usual 96 mmHg even though it looks only mildly high. A pounding headache, flushing and sweating above the injury, and reflex bradycardia complete the picture.

Why this is autonomic dysreflexia

The patient’s injury is at C6, which is above the T6 neurologic level. After spinal shock resolves, patients with lesions at or above T6 can develop autonomic dysreflexia (AD) when a noxious stimulus below the injury triggers an exaggerated sympathetic response. The most common trigger is bladder overdistension, and this patient is 30 minutes before his next scheduled intermittent catheterization, making a full bladder highly likely ^[1][2][3].

A systolic blood pressure rise of 20 to 40 mmHg or more above the patient’s baseline is considered significant in AD. His usual BP is 96/60 mmHg, and the current reading of 150/92 mmHg represents a 54 mmHg systolic increase. Even though 150 mmHg may appear only mildly elevated in a general adult, it is a dramatic rise for this individual and meets the threshold for AD.

The clinical picture completes the diagnosis. The pounding headache, flushed and sweaty face and neck, and blurred vision reflect vasodilation and sweating above the injury level, while reflex bradycardia at 54/min is the baroreceptor-mediated vagal response to the sudden hypertension ^[2]. These findings are classic for AD and do not fit the other options.

Finding	Autonomic dysreflexia	Intracranial pressure rise	Migraine	Anxiety hypertension
BP pattern	Sudden rise ≥20–40 mmHg above baseline	Often with widening pulse pressure, bradycardia, altered consciousness	Usually no significant BP elevation	Mild to moderate rise, no reflex bradycardia
Heart rate	Reflex bradycardia	Bradycardia possible but with Cushing triad	Normal or slightly increased	Tachycardia more common
Skin above injury	Flushed, sweaty	Not characteristic	Pallor or nausea possible	Diaphoresis possible but diffuse
Trigger	Bladder or bowel distension below injury	Trauma, mass, hemorrhage	Light, stress, foods	Psychological stress

Key point! In a patient with SCI at T6 or above, any sudden headache with elevated BP should be treated as AD until proven otherwise. The first nursing action is to sit the patient upright, check the bladder and catheter, and remove the noxious stimulus. Watch out! Do not dismiss a BP of 150/92 mmHg as “not that high” — the comparison must always be made against the patient’s own baseline, not population norms.

The systematic review confirms that neurogenic detrusor overactivity (NDO) is a major trigger for AD, and managing bladder overactivity is a core strategy for preventing recurrent episodes ^[1]. One source reports that bladder overdistension accounts for approximately 85% of AD cases, underscoring why a full bladder is the most likely explanation here ^[3].