Blackouts and faints

• Vasovagal syncope: Triggered by prolonged standing, emotional stress, or pain; often preceded by a feeling of warmth, nausea, or lightheadedness.
• Orthostatic hypotension: Drop in blood pressure on standing, often due to dehydration, medications, or autonomic dysfunction.
• Arrhythmias: Sudden onset, may occur without warning; palpitations, chest pain, or breathlessness may be present.
• Structural heart disease: Exertional syncope, associated with conditions such as aortic stenosis, hypertrophic cardiomyopathy.
• Pulmonary embolism: Syncope associated with pleuritic chest pain, dyspnoea, and haemoptysis.

• Seizures: Sudden loss of consciousness with tonic-clonic movements, tongue biting, or post-ictal confusion.
• Transient Ischaemic Attack (TIA): Sudden, focal neurological deficit; often brief and self-limiting.
• Subarachnoid haemorrhage: Sudden, severe headache (“thunderclap”), often with neck stiffness, photophobia, and reduced consciousness.
• Migraine: Aura with visual disturbances, headache, photophobia; may have transient neurological symptoms.

• Hypoglycaemia: Confusion, diaphoresis, tremor, often in diabetic patients on insulin or oral hypoglycaemic agents.
• Electrolyte imbalances: Especially hyponatraemia or hyperkalaemia; may present with confusion, weakness, and altered consciousness.
• Adrenal insufficiency: Fatigue, weight loss, hyperpigmentation, hypotension, particularly in Addison’s disease.

• Panic attacks: Hyperventilation, palpitations, a sense of impending doom, often with a clear psychological trigger.
• Psychogenic non-epileptic seizures (PNES): Events resembling seizures but without EEG changes; often associated with emotional distress.
• Somatization disorders: Multiple unexplained symptoms across different organ systems.

• Hypovolaemia: Due to blood loss, dehydration, or severe diarrhoea; presents with dizziness, tachycardia, and hypotension.
• Medications: Antihypertensives, diuretics, and psychotropic medications may cause hypotension and syncope.
• Intoxication: Alcohol or drug use, presenting with altered consciousness, unsteady gait, and confusion.

Sudden onset may suggest an arrhythmia or seizure, while a gradual onset with prodromal symptoms might indicate vasovagal syncope or orthostatic hypotension. Transient episodes are often related to TIA or hypoglycaemia, whereas prolonged episodes could indicate more serious conditions such as cardiac arrhythmias or subarachnoid haemorrhage.

Presence of palpitations may indicate an arrhythmia. Chest pain could point towards a cardiac cause, while headache or focal neurological symptoms suggest a neurological cause such as TIA or subarachnoid haemorrhage. Sweating, tremor, and confusion could be indicative of hypoglycaemia.

Syncope occurring in a hot environment, during or after exertion, or associated with stress, is likely vasovagal. Syncope on standing may suggest orthostatic hypotension, while syncope during exertion could be related to structural heart disease or arrhythmia.

Past medical history of cardiovascular disease, seizures, or diabetes mellitus can provide clues to the underlying cause. A drug history including antihypertensives, diuretics, and psychotropic medications may reveal potential contributors. Family history of sudden cardiac death or arrhythmias is important. Social history, including alcohol or substance use, can also be relevant.

• Electrocardiogram (ECG): To assess for arrhythmias, myocardial ischemia, or structural abnormalities.
• Blood glucose: To rule out hypoglycaemia.
• Full blood count: To check for anaemia or infection.
• Urea and electrolytes: To assess for electrolyte imbalances, dehydration, or renal function.
• Cardiac enzymes (e.g., troponin): If myocardial infarction is suspected.

• Echocardiography: If structural heart disease is suspected.
• Holter monitor or event recorder: For suspected intermittent arrhythmias.
• Tilt-table test: For diagnosing vasovagal syncope or orthostatic hypotension.
• CT/MRI brain: If a neurological cause such as stroke or tumour is suspected.
• EEG: If epilepsy or non-epileptic attack disorder (NEAD) is suspected.