Discussion
The causes of falls in elderly people are often complex, and it can be difficult to identify the main contributing factor. Thorough investigation and intervention against all controllable causes takes account of this and has proven efficacy (2) . The patient-reported medical history, including the circumstances and symptoms before, during and after the fall and any previous falls, is used together with information on comorbidities and other risk factors for more targeted assessment. This should be accompanied by a medication review, investigation of physical function, including assessment of gait and balance as well as inspection of feet/footwear, and assessment of the patient’s fear of falling.
The clinical examination also includes a cursory neurological examination and cognitive assessment. There is overlap between falls and syncope (4) , and information from witnesses or those known to the patient is often lacking because patients typically fall when they are alone. Knowledge and awareness of this adds to the fall risk assessment in accordance with the guidelines (2) and makes it, in our opinion, more interesting.
Syncope is a brief, self-limiting loss of consciousness and postural tone due to a global disturbance in cerebral perfusion. Syncope must be differentiated from epileptic seizures, coma, hypoglycaemia, vertigo etc., and this is achieved primarily on the basis of medical history, often supplemented by information from others. Syncope is commonly divided into three main types based on mechanism (6) , as described recently in this journal (7) , and illustrated in a somewhat simplified form in Figure 3.
Figure 3 Schematic showing classification of syncope subtypes, with basic details of mechanisms and causes
Orthostatic syncope is syncope as a component of orthostatism, a more or less continuous failure to maintain blood pressure when in an upright position, and is most often caused by antihypertensive drugs or autonomic failure. Orthostatic blood pressure is measured in supine and upright positions after one and three minutes, and a drop in blood pressure of 20 mm Hg systolic or 10 mm Hg diastolic or to less than 90 mm Hg systolic, together with symptoms such as dizziness, cold sweats or fatigue, is considered diagnostic of orthostatic hypotension and may explain falls.
Cardiac syncope is caused by a sudden drop in cardiac output due to arrhythmia or structural heart disease (valve defects, proximal coronary artery disease, hypertrophic obstructive cardiomyopathy or myxoma). Syncope in a patient with heart disease should always be suspected to be cardiac. Untreated, these patients have a poor prognosis and they should undergo cardiac evaluation, often on an urgent basis. They are seldom referred for fall risk assessment at the geriatric outpatient clinic. Palpitations, symptoms during exertion or while supine, and sudden deaths in family members under the age of 40 should create suspicion of cardiac syncope (8) . Left bundle branch block, or bi- or trifascicular block are clues indicating cardiac conduction abnormalities, and in the case of otherwise unexplained syncope, intermittent AV block is such a likely explanation that a pacemaker is indicated.
Reflex syncope is a temporary and short-lived dysfunction of an otherwise well-functioning system of blood-pressure regulation. The fall in blood pressure is due to vasodilatation and/or bradycardia, in varying combination. Reflex syncope can often be diagnosed on the basis of the patient-reported medical history alone, and there is almost always an orthostatic component in the form of syncope while upright, or sometimes just while sitting. Among the elderly, carotid sinus syncope is the most common reflex syncope (5) . Micturition syncope and syncope related to coughing or meals are also relatively common forms of reflex syncope in the elderly.
Carotid sinus syncope is rare before the age of 40. The classic variant where a tight collar or pressure on the neck triggers syncope is rare. Turning the head or scratching oneself on the neck may be sufficient to trigger syncope, and in the elderly such syncope can occur without known carotid sinus stimulation. Most commonly, no triggering mechanism is identified, but the diagnosis is made by carotid sinus massage. It is seldom that one observes such convincing symptom reproduction as that shown here – the patient’s spontaneous exclamation as she came round confirms the relationship between the symptom of falls and the cause, carotid sinus syncope.
The requirement for symptom reproduction is important, because carotid sinus hypersensitivity is common in the elderly, especially in men (5) . If syncope is not suspected and/or there is an awareness of other factors that can readily explain falls, the discovery of a cardioinhibitory response without symptoms will probably not have any significance for the risk of falls, and the patient should consequently not be treated with a pacemaker. According to new guidelines, pacemakers are usually only indicated if there is a demonstrated sinus pause of at least six seconds. At the same time, evidence of a reduced syncope relapse rate supports an effect of pacing (9) .
It is important not to overstate the efficacy of pacemaker therapy in reducing the tendency to fall, because additional causes are present in the majority of cases. Among the most frail, smaller haemodynamic changes can also trigger dizziness and unsteadiness with subsequent falls, even if they do not induce syncope (5) . In these patients, tailored strength and balance training could be effective in preventing further falls, even when syncope is identified and treated.
Much of the syncope assessment can be performed in general practice. A thorough medical history from the patient with emphasis on symptoms and triggering situations will often reveal whether there is vasovagal syncope. If that is the case, the mechanism can be explained and the patient reassured. It is important to ask directly about alarm symptoms: syncope upon exertion or while supine, the absence of triggering factors and cases of sudden death in the family must lead to referral.
Carotid sinus massage can also be performed in general practice, in accordance with the guidelines outlined above. Continuous ECG monitoring during the manipulation itself will document any sinus pause. If the diagnosis of syncope is uncertain or there is a risk of serious consequences, the patient must be referred. Elderly people can pose a diagnostic challenge due to comorbidity, uncertainty with regard to the self-reported medical history and the risk of serious consequences.