Dizziness

Dizziness here means a sensation of lightheadedness, faintness or unsteadiness without an illusion of movement. Illusory rotation or motion is vertigo and has a different approach. Most dizziness is cardiovascular, metabolic, drug related or psychological; a small proportion is due to arrhythmia, structural heart disease, haemorrhage or posterior circulation ischaemia.

Mechanisms. Reduced cerebral perfusion (orthostatic, arrhythmic, low output, haemorrhage), metabolic disturbance (glucose, sodium, oxygen), drug effect, impaired multisensory input (vision, proprioception, vestibular), and anxiety with hyperventilation.

Classification. Presyncope (near faint), disequilibrium (unsteadiness on walking), and non specific lightheadedness including persistent postural perceptual dizziness. Patients often describe more than one type.

Temporal patterns. Brief episodes with a clear trigger (standing, exertion, micturition, head turn), recurrent episodes without trigger, and continuous symptoms for weeks.

Orthostatic hypotension is a sustained fall in systolic pressure of 20 mmHg or more, or in diastolic pressure of 10 mmHg or more, within 3 minutes of standing, or a systolic pressure under 90 mmHg. Postural tachycardia syndrome is a heart rate rise of 30 beats/min or more within 10 minutes of standing, without orthostatic hypotension, with symptoms.

History. Ask the patient to describe the sensation without prompting. Establish duration of each episode, triggers, relation to posture, meals, exertion, hot environments, urination or cough, and associated symptoms: palpitations, chest pain, dyspnoea, tinnitus, hearing loss, headache, visual symptoms, diplopia, dysarthria, dysphagia, limb weakness, sweating, tremor, anxiety, paraesthesia around the mouth. Ask about blood loss (melaena, menstrual loss), vomiting, diarrhoea, fluid intake, weight loss and pregnancy.

Drug and background history. Antihypertensives, diuretics, alpha blockers, nitrates, phosphodiesterase inhibitors, antidepressants, antipsychotics, benzodiazepines, anticonvulsants, levodopa, opioids, insulin and sulphonylureas, and alcohol. Diabetes, Parkinson disease, cardiac disease, anaemia, long term corticosteroid use, family history of sudden death.

Examination. Lying blood pressure and pulse after 5 minutes, then standing at 1 and 3 minutes. Pulse rhythm and rate, murmurs (aortic stenosis, hypertrophic cardiomyopathy), carotid bruits, jugular venous pressure, signs of heart failure, hydration, pallor, rectal examination if bleeding is suspected, fundi, visual acuity, full neurological examination including gait, tandem walk, Romberg test, sensation and cerebellar signs, and a Dix Hallpike manoeuvre if positional spinning is reported.

Red flags

• Dizziness during exertion, or with chest pain or palpitations
• Family history of sudden death, or an abnormal ECG
• New murmur, heart failure, or syncope
• Melaena, haematemesis, heavy bleeding or pregnancy
• Headache, new neurological signs, diplopia, dysarthria or dysphagia
• Fever or sepsis
• Glucose abnormality

Special groups. Older adults: multifactorial, with drugs, orthostasis, sensory loss and cardiac disease contributing; assess for falls. Pregnancy: supine hypotension in late pregnancy, and anaemia.

Cardiovascular

• Orthostatic hypotension: volume depletion, drugs, neurogenic autonomic failure (Parkinson disease, multiple system atrophy, diabetic autonomic neuropathy, amyloidosis), adrenal insufficiency
• Vasovagal and situational syncope, carotid sinus hypersensitivity
• Bradyarrhythmia (sinus node disease, atrioventricular block), tachyarrhythmia (atrial fibrillation, ventricular tachycardia, supraventricular tachycardia)
• Aortic stenosis, hypertrophic cardiomyopathy, heart failure, pulmonary embolism, pulmonary hypertension
• Aortic dissection, subclavian steal
• Postural tachycardia syndrome

Haematological and blood loss

• Anaemia, acute haemorrhage including gastrointestinal bleed and ectopic pregnancy

Metabolic and endocrine

• Hypoglycaemia, hyperglycaemia, hyponatraemia, hypocalcaemia
• Hypothyroidism, thyrotoxicosis, adrenal insufficiency
• Hypoxia, hypercapnia, carbon monoxide poisoning

Drugs and toxins

• Antihypertensives, diuretics, nitrates, antidepressants, antipsychotics, sedatives, anticonvulsants, alcohol

Neurological

• Transient ischaemic attack and posterior circulation stroke
• Parkinson disease, cerebellar disease, peripheral neuropathy, myelopathy
• Multisensory deficit of ageing

Psychiatric and functional

• Anxiety and panic with hyperventilation, depression, persistent postural perceptual dizziness, somatic symptom disorder

Other

• Sepsis, pregnancy, refractive error or new spectacles, cervicogenic dizziness

Reasoning. First exclude a life threatening cause with bedside tests, then use triggers and timing to direct further investigation, and avoid brain imaging unless there are neurological findings.

First line. Lying and standing blood pressure and heart rate; capillary glucose; pulse oximetry; temperature; 12 lead ECG (look for rhythm disturbance, atrioventricular block, bundle branch block, pre-excitation, prolonged QT, Brugada pattern, left ventricular hypertrophy and ischaemia).

Blood tests. Full blood count, urea, electrolytes, creatinine, glucose, calcium, magnesium, thyroid stimulating hormone, ferritin and vitamin B12 as indicated; troponin if chest pain or ECG changes; pregnancy test in women of reproductive age. For suspected adrenal insufficiency (hypotension, hyponatraemia, hyperkalaemia, long term steroid use): an early morning cortisol, and a tetracosactide stimulation test (250 micrograms IV or IM with cortisol at 30 minutes) when the result is intermediate.

Targeted tests. Echocardiography for murmur, heart failure, abnormal ECG or exertional symptoms. Ambulatory ECG monitoring (24 to 72 hours, or a longer event recorder for infrequent episodes). Tilt table testing for suspected vasovagal or postural tachycardia syndrome when the history is not diagnostic. Autonomic function tests for suspected neurogenic orthostatic hypotension. MRI brain and vessel imaging only for neurological signs. Hyperventilation reproduction of symptoms supports anxiety related dizziness, but does not exclude other causes.

Limitations. A normal resting ECG does not exclude an intermittent arrhythmia. Orthostatic blood pressure changes are common in older adults without symptoms.

Immediate stabilisation. Lie the patient flat and raise the legs. Treat the cause found:

• Hypoglycaemia (glucose under 4 mmol/L): 15 to 20 g oral glucose, rechecked after 15 minutes; if unable to swallow, glucagon 1 mg IM (adjust to the product label) or 10 percent glucose 150 to 200 mL IV over 15 minutes.
• Volume depletion: 0.9 percent sodium chloride 500 mL to 1 L IV bolus, reassessed after each bolus; oral rehydration for mild cases.
• Haemorrhage, symptomatic bradycardia, tachyarrhythmia or sepsis: emergency resuscitation and referral.

Orthostatic hypotension

• Withdraw or reduce the culprit drug where possible.
• Fluid intake 2 to 3 L daily and salt 6 to 9 g daily in the absence of heart failure, renal disease or supine hypertension.
• Slow postural change, physical counter manoeuvres (leg crossing, muscle tensing), waist high compression stockings or abdominal binder, and raising the head of the bed by 10 to 20 degrees.
• Midodrine 2.5 mg orally three times daily, increased weekly to 10 mg three times daily; maximum 10 mg three times daily; last dose at least 4 hours before bed. Monitor supine blood pressure. Contraindicated in severe cardiac disease, urinary retention, and supine hypertension. Start at 2.5 mg in renal impairment.
• Fludrocortisone 0.05 to 0.1 mg orally once daily, increased by 0.05 to 0.1 mg each week to a maximum of 0.3 mg daily. Monitor potassium, oedema and supine blood pressure. Avoid in heart failure.

Vasovagal syncope and presyncope. Education on triggers, adequate fluids and salt, counter manoeuvres, and avoiding prolonged standing.

Anaemia, thyroid, adrenal and other endocrine causes. Treat the cause. Adrenal crisis: hydrocortisone 100 mg IV immediately, then 50 mg IV every 6 hours, with 0.9 percent sodium chloride 1 L over the first hour.

Anxiety and persistent postural perceptual dizziness. Explanation, cognitive behavioural therapy and vestibular rehabilitation through specialist services; a selective serotonin reuptake inhibitor in selected patients.

Monitoring. Lying and standing blood pressure after each drug change; electrolytes with diuretics and fludrocortisone; symptom diary.

Referral and escalation. Urgent cardiology for exertional symptoms, abnormal ECG, structural heart disease or suspected arrhythmia. Neurology for suspected autonomic failure or posterior circulation events. Same day for any new neurological sign.

Admission criteria. Suspected arrhythmia, structural heart disease, bleeding, new neurological deficit, sepsis, severe electrolyte disturbance, or inability to mobilise safely.

Discharge and safety netting. Return for syncope, chest pain, palpitations, black stools, weakness, speech or visual symptoms. Advise on driving restrictions where syncope or incapacitating symptoms have occurred. Follow up in 1 to 2 weeks.