Episodes of transient disturbance of consciousness and falls are common clinical problems. It is usually possible to distinguish between a ‘fit’ (a seizure), a ‘faint’ (syncope) and other types of attack from the history given by the patient and the account of an eye witness.
Syncope (situational or vasovagal)
Narcolepsy and cataplexy
Transient ischaemic attacks
Psychogen ic attacks
Night terrors }
Syncope (‘fainting’, vasovagal attacks) and related disorders. Sudden reflex bradycardia and peripheral and splanchnic vasodilatation leading to loss of consciousness occurs commonly in response to prolonged standing, fear, venesection or pain. This is also known as neurocardiogenic syncope. It almost never occurs in the recumbent posture. The subject falls to the ground and is unconscious for less than 2 minutes. Recovery is rapid. A few jerking movements are uncommon, but do occur. Incontinence of urine is exceptional. This is the ‘simple faint’ from which the majority of the population suffer at some time, particularly in childhood, in youth or in pregnancy. Syncope may occur after micturition in men(particularly at night) and when the venous return to the heart is obstructed by breath-holding and severe coughing.The syndrome of carotid sinus syncope is believed to be due to excessive sensitivity of the sinus to external pressure. It may occur in elderly patients who lose consciousness on touching of the neck.
Postural hypotension occurs in patients with impaired utonomic reflexes, e.g. in the elderly, in autonomic neuropathy, or with ganglion-blocking drugs used in hypertension, with phenothiazines, levodopa or tricyclic antidepressants. A tilt test will show hypotension as the patient is raised to the vertical and is useful in diagnosis.Transient cerebral ischaemia in the posterior cerebral circulation is a cause of episodes of loss of consciousness in patients with cervical spondylosis in which vertebral artery compression occurs. Cardiac arrhythmias (cardiac syncope, Stokes-Adams attacks-see p.527) are important causes of recurrent episodes of loss of consciousness, particularly in the elderly. There is sometimes a preceding warning of palpitations (either f ast or slow). The loss of consciousness is sudden and accompanied by pallor. Exceptionally, there are convulsive movements (‘anoxic convulsions’). Flushing may occur when the patient recovers. The usual cardiac arrhythmias that cause loss of consciousness are paroxysmal bradycardias (e.g. in complete heart block) or tachycardias (e.g. ventricular tachycardias, ventricular fibrillation). Supraventricular tachycardias are unusual causes of loss of consciousness.
Effort syncope (syncope on exertion) is of cardiac origin (e.g. aortic stenosis, hypertrophic obstructive cardiomyopathy) .
Syncope and related conditions where cerebral blood flow is impaired can usually be distinguished from epilepsy on the clinical history alone. Cardiac monitoring may sometimes be necessary to detect an arrhythmia. Tilt testing (see p. 541) is useful in neurocardiogenic syncope.
The immediate management of syncope, or impending syncope, is to lie the patient down, to elevate the lower limbs and to record the pulse. In the rare circumstances where cerebral blood flow cannot be restored, e.g. in a dentist’s chair, syncope may be followed by cerebral infarction.
These sudden episodes of weakness of the lower limbs with falling but without loss of consciousness occur in middle-aged women. They are believed to be due to sudden changes in tone in the lower limbs, presumably of brain stem origin. Previously they have been regarded as forms of TIA, from which they are distinct.Panic attacks. night terrors. psychogenic attacks and hyperventi lation Panic attacks are usually associated with an autonomic disturbance, e.g. tachycardia, sweating and piloerection.
Consciousness is usually preserved. Hyperventilation (see below) is common. Night terrors are sudden episodes seen in children who awake as if from a dream in a state of terror.
Psychogenic attacks cause considerable difficulty in diagnosis. Attacks resembling grand mal fits may occur but more usually there are bizarre and irregular limb movements.
The alkalosis accompanying hyperventilation leads to a feeling of light-headedness, which may be accompanied by circumoral and peripheral tingling and tetany (e.g. carpopedal spasm) (see p. 430).
Hypoglycaemia (see also p. 852) Hypoglycaemia causes attacks in which the patient either feels unwell or may lose consciousness, sometimes with a convulsion. There is often some warning, with hunger, shaking and sweating. There is prompt relief with intravenous (or oral) glucose.
Hypoglycaemic attacks unrelated to diabetes are rare. ost patients who feel unwell after fasting or in the early morning have no serious organic disease.
A grand mal fit may accompany hypocalcaemia.
Vertigo Acute episodes of vertigo may cause prostration: consciousness is sometimes lost for a few seconds.
Choking Sudden prostration sometimes follows choking, particularly when a large bolus of meat obstructs the larynx. The patient goes blue, is speechless and may die in the attack if the obstruction is not relieved. Treatment involves immediately grasping the patient around the abdomen and squeezing hard in an effort to eject the food (Heimlich manoeuvre, see p. 656).
SLEEP AND ITS DISTURBANCES
Sleep is required on a regular basis The reason for this is unclear; it is postulated that the laying down of memory is one important component. Complex pathways between the cortex and reticular formation are involved in the production and maintenance of sleep. During a normal night’s sleep, there are periods of deep sleep associated with rapid eye movement (REM). Dreaming occurs during REM sleep. In insomnia, sleep is fitful. Less time than usual is spent in REM sleep. Sleep requirement falls to as little as 4 hours a night in old age. Insomnia, particularly early morning waking, is a common symptom of depression (see p. 970). In practice, insomnia itself is rarely a feature of serious organic neurological disease but in the elderly nocturnal confusion and/or nightmares are caused by drugs and organic brain disease. In sleep apnoea, the normal short periods of apnoea seen during REM sleep are prolonged. This occurs with brain stem lesions and with upper airways obstruction, when it is accompanied by snoring. The latter is particularly important in patients with chronic bronchitis and emphysema, who may become severely hypoxic.
Narcolepsy and cataplexy Narcoleptic attacks are periods of irresistible sleep in inappropriate circumstances. They may occur when there is little distraction, after meals, while travelling in a vehicle, or without obvious cause. Genetically, narcolepsy is strongly associated with HLA-DR2 and HLA-DQwl antigens
Cataplexy is a sudden loss of tone in the lower limbs with preservation of consciousness. Attacks are set off by sudden surprise or emotion. The two conditions are related and may be accompanied by hypnagogic hallucinations (terrifying hallucinations on falling asleep), hypnopompic hallucinations (on waking) and sleep paralysis (a frightening inability to move whilst drowsy). The EEG is normal in these attacks.
Treatment is with methylphenidate, other amphetamine- ike drugs, or small doses of tricyclic antidepressants.