Neurocardiogenic syncope causes

Neurocardiogenic syncope is usually triggered by an exaggerated nervous-system response that briefly lowers blood pressure or heart rate. Standing for a long time, heat, pain, fear, emotional upset, needles and straining can set it off. Fluid loss, an empty stomach or medicines that lower blood pressure may increase susceptibility.

When blood pools in the legs or the body reacts strongly to a trigger, the heart may pump less effectively for a short period and blood vessels may relax. The resulting drop in brain blood flow can cause pallor, sweating, queasiness, ringing in the ears or tunnel vision before a faint. A clinician also considers other explanations: dehydration can reduce circulating fluid, anaemia can limit oxygen delivery, hypoglycaemia can affect brain function, and atrial fibrillation can disturb the heartbeat.

Keep fluids regular unless you have been told to restrict them, eat at predictable times, avoid standing still in hot settings and flex your leg muscles when you must stand. At the first warning, lie down or sit with your head low. Record what happened beforehand, your position, warning symptoms, medicines and recovery time. This detail helps a clinician distinguish a reflex faint from a heart, metabolic or neurological problem.

Get emergency help for fainting with chest pain, difficult breathing, a pounding or irregular heartbeat, severe injury, seizure-like movements, confusion that persists, or failure to wake normally. Prompt medical review is also needed when an episode happens during exercise, while lying down, without warning, or repeatedly. Do not assume a familiar trigger rules out a different cause.

Ask which trigger is most plausible, whether blood tests or an ECG are needed, how to manage fluids and meals safely, and whether a medicine could be contributing. Ask what information a witness should record if another episode occurs.