Conditions

Giddiness

Dizziness and headaches can be symptoms of high blood pressure, vascular issues, or circulation problems

Syncope is a transient loss of consciousness caused by temporary global cerebral hypoperfusion, with spontaneous and complete recovery. Presyncope — lightheadedness, visual dimming, or near-blackout without full loss of consciousness — shares the same underlying mechanisms. Both are common presentations requiring structured evaluation, as the cause ranges from entirely benign reflex responses to immediately life-threatening cardiac conditions. Accurate risk stratification determines which patients require urgent investigation and which can be safely managed as outpatients.

Classification of Syncope

• Reflex (neurally mediated) syncope is the most common category, encompassing vasovagal syncope — triggered by prolonged standing, heat, pain, or emotional stress — and situational syncope from coughing, micturition, or swallowing. Carotid sinus syndrome, triggered by head turning or neck pressure, is an important cause in older patients. Reflex syncope is generally benign but can cause injury from falls and significantly impairs quality of life.
• Orthostatic hypotension causes syncope or presyncope on standing due to a failure of compensatory blood pressure response. It is common in older patients, those on antihypertensive or diuretic therapy, and patients with autonomic neuropathy from diabetes or Parkinson's disease. POTS (postural orthostatic tachycardia syndrome) — an excessive heart rate rise on standing without a blood pressure drop — predominantly affects younger women and causes debilitating orthostatic symptoms without true syncope.
• Cardiac syncope arises from arrhythmias or structural heart disease causing sudden reduction in cardiac output. It carries the highest risk of sudden death and requires urgent evaluation. Arrhythmic causes include high-degree heart block, sick sinus syndrome, ventricular tachycardia, and ventricular fibrillation. Structural causes include severe aortic stenosis, hypertrophic obstructive cardiomyopathy, and acute myocardial infarction.

Red Flag Features Requiring Urgent Assessment

Syncope during exertion, syncope preceded by palpitations or chest pain, syncope without prodrome in a patient with structural heart disease, and syncope associated with an abnormal ECG are high-risk features that mandate urgent cardiac evaluation — same-day assessment or emergency presentation where indicated. A family history of sudden cardiac death in a young relative raises the possibility of an inherited arrhythmia syndrome and requires specialist review. Call 995 if syncope occurs with persisting chest pain, breathlessness, or neurological symptoms.

Diagnosis

Evaluation follows a structured pathway. History — characterising triggers, prodrome, duration, recovery, and witnessed features — frequently establishes the diagnosis before any investigation. A resting 12-lead ECG identifies arrhythmias, conduction disease, pre-excitation, Brugada pattern, or QT prolongation. Echocardiography excludes structural heart disease. Orthostatic blood pressure measurement — lying, then standing at one and three minutes — diagnoses orthostatic hypotension. Ambulatory ECG monitoring via Holter or extended event recorder captures arrhythmias in patients with frequent episodes. For unexplained recurrent syncope, an implantable loop recorder (ILR) — a small subcutaneous device providing continuous ECG monitoring for up to three years — is the investigation of choice and has the highest diagnostic yield for infrequent cardiac syncope. Tilt table testing evaluates vasovagal and orthostatic mechanisms in selected patients.

Treatment

Treatment is directed at the specific syncope subtype. Vasovagal syncope is managed with patient education, avoidance of triggers, increased fluid and salt intake, compression stockings, and physical counterpressure manoeuvres — pharmacotherapy with fludrocortisone or midodrine is reserved for refractory cases. Orthostatic hypotension is treated by rationalising antihypertensives, increasing fluid and salt intake, and using compression garments; midodrine or fludrocortisone are added when conservative measures are insufficient. POTS is managed with increased fluid and sodium intake, graduated exercise, compression garments, and beta-blockers or ivabradine where indicated. Cardiac syncope is treated according to the underlying arrhythmia or structural cause — pacemaker implantation for bradyarrhythmias, ICD or catheter ablation for ventricular arrhythmias, and valve intervention for obstructive structural disease.

Experiencing unexplained dizziness, fainting, or near-blackout episodes in Singapore? Dr. Peter Chang consults at Paragon Medical Centre, Orchard Road. Book a specialist assessment today.