Blackouts and ‘funny do’s’

Blackouts are one of the most common presentations in neurology, accounting for 18% of new neurological outpatients. The most common causes are seizures or syncope. While a list of possible causes is long, the clinical history, particularly with an account from a witness, will usually define the nature of the attack and direct investigations.

History

‘Blackout’ is a term that is usually used to mean episodes of loss of consciousness but some patients use it to mean episodes of altered consciousness. Other patients can mean a range of other things including dizzy feelings, memory loss or occasionally even episodes of weakness without impaired consciousness. It is important to find out what they mean. To help you do this, the range of feelings most often included within the term are discussed below. Other key aspects of the history include a detailed description of the blackout – what the patient was doing, any precipitating factors and the time course of the blackout, including any prodromal symptoms, aura immediately before the blackout, features of the blackout (ictus) itself and any post-ictal effects are all important in making the diagnosis. A witnessed account of what happened is essential. The widespread availability of mobile phones makes tracking down the person who saw the event easier.

Examination

The examination is usually normal in patients with blackouts of all causes. Examinations of the cardiovascular system and the nervous system are particularly important – look for pulse irregularity, evidence of cardiac failure, murmurs, extracranial bruits, erect and supine blood pressures and any focal neurological signs.

Types of blackouts and ‘funny do’s’

These may occur at any time and in any position (Fig. 1). The patient may have a warning (aura), such as a smell or taste or simply a strange feeling (see below). The aura is usually brief (a few seconds). There may be no warning. The patient may be observed to go blank or be lip smacking before losing consciousness. The patient then goes stiff and lets out a grunt. The arms and legs go stiff for a period and the jaw is clenched tight. This may be followed by a jerking of the limbs. This usually goes on for 2–3 min. The patient usually goes into a deep sleep. On coming round, the patient is muddled. Patients frequently bite their tongue and pass urine.