Transient loss of consciousness (TLoC)

Transient loss of consciousness (TLoC), especially if there is little or no warning, is a dangerous and disabling condition.

TLoC is very common: it affects up to half the population in the UK at some point in their lives

• TLoC may be defined as the spontaneous loss of consciousness with complete recovery. In this context, complete recovery would involve full recovery of consciousness without any residual neurological deficit
• an episode of TLoC is often described as a 'blackout' or a 'collapse'

The diagnosis of the underlying disorder is important because:

• treatment is usually available
• some causes are life-threatening

The commonest causes of transient loss of consciousness are cardiovascular and epileptic, although metabolic and psychiatric causes are important.

Blackouts in adults (2)

• urgently refer adults with new-onset blackouts (transient loss of consciousness), accompanied by features that are strongly suggestive of epileptic seizures, for neurological assessment
• do not routinely refer adults with blackouts if there are clear features of vasovagal syncope, even if associated with brief jerking of the limbs

References:

1. NICE (November 2023). Transient loss of consciousness ('blackouts') management in adults and young people.
2. NICE (May 2019). Suspected neurological conditions: recognition and referral.