Syncope refers to a “transient loss of consciousness due to reduced cerebral perfusion.”  Transient loss of consciousness is a very common presentation, affecting up to half the population in the UK at some point in their lives. Patients often describe these episodes as “blackout” or “collapse”. Cardiovascular diseases are the commonest cause however the differentials are wide (therefore a thorough clinical history, examination and focused investigation are absolutely essential to illicit the underlying cause!)



(important to obtain eyewitness/collateral history)

  • Before attack:

          -Position: standing, lying down, sitting

          -Activity: during/after exercise, change in posture, micturition, coughing

          -Prodromal symptoms?: lightheadedness, headache, aura, chest pain,

                                            breathlessness,dysarthria, limb weakness etc.

  • During attack:

          -Establish whether there was Loss of Consciousness! -duration

          -Jerky movements that may suggest a seizure (cerebral hypoxia of any cause may

           also cause transient abnormal movements)

          -Incontinence, up-rolling of eyeball, tongue-biting

          -Injuries sustained during the event

  • After attack:

          -Speed of recovery

          -Level of consciousness on recovery


  • Background questions     

           Past medical history: diabetes, hypertension, epilepsy, ischemic heart disease

           Medication history:  insulin, anti-hypertensives, NSAIDs etc.

           Menstrual/Gynaecology history: pregnancy, LMP, menorrhagia etc.

           Substance Abuse



    • Signs of blood loss: pallor, tachycardia, hypotension
    • Pulse: rhythm, character, volume
    • Heart: murmurs, signs of heart failure, tamponade
    • Carotid bruit: possible TIA, stroke
    • Neurological deficit
    • Rectal examination: malaena
    • Look for injuries!


    Key features


    For all patients:

    These initial investigations will identify the underlying cause in over a third of patients presenting with syncope

    • Erect & Supine BP

              -BP Readings at supine position then immediately & after 3mins of standing upright

              -Positive result: Drop of 20mmHg  Systolic and 10mmHg Diastolic BP

    • 12-lead ECG
    • FBC, U&E, Glucose, TFT


    Specific Investigations:

    The choice of these further investigations will depend upon clinical suspicion from history, examination and initial investigations.

    • 24-hour ECG tape (arrythmia)
    • Echocardiography (structural heart disease, heart failure)
    • Tilt testing (vasovagal syncope)

              -patient lies flat for 10mins and attached to cardiac & BP monitor

              -tilted upright at 70degrees and observed for 30mins for signs of syncope.

               GTN spray is sometimes used.

    • Carotid sinus massage (carotid sinus hypersensitivity)

              -DO NOT perform if carotid bruit present or recent stroke

              -massage carotid sinuses for 6 seconds while monitoring BP & ECG

              -positive: sinus pause for >3s or fall in systolic BP >50mmHg

    • Head CT scan (stroke, intracranial haemorrhage)
    • Urine HCG (ectopic pregnancy)



    Do not forget to differentiate syncope from-

    • Vertigo: vestibulitis, Benign paroxysmal positional vertigo, Meniere’s
    • Loss of balance: musculoskeletal, vision problem, loss of propioception, ataxia (especially in elderly patients!)




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