driving (and simple faint)

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Transient loss of consciousness ('blackouts') - or lost/altered awareness

Transient loss of consciousness (TLoC) or 'blackout' is very common - it affects up to half the population in the UK at some point in their lives.

An estimated 3% of A&E presentations and 1% of hospital admissions are due to TLoC.

Road traffic collisions resulting from blackouts are two or three times more common than those resulting from seizures. Recurrent TLoC (more than one isolated event), not including syncope, is uncommon - but always requires detailed medical assessment.

In relation to TLoC, three features are of note to medical practitioners:

  • provocation
  • posture
  • prodrome.

In relation to road safety, however, the two most important features are:

  • prodrom - are there warning symptoms sufficient in both nature and duration?
  • posture - do the episodes of TLoC occur while sitting?

A prodrome must allow time for a driver to find a safe place to stop before losing consciousness. A prodrome is reliable if the signs are clear, consistent across all events and provide sufficient duration to find a safe stop, or unreliable if these are absent.

Licence holders or applicants should be informed that they must notify the DVLA when TLoC occurs while sitting

For syncope occurring while standing or sitting, the following factors indicate high risk:

  • abnormal ECG
  • clinical evidence of structural heart disease.

Further investigations such as 48-hour ambulatory ECG, echocardiography and exercise testing may be indicated after specialist opinion has been sought.

Transient loss of consciousness - solitary episode

Typical vasovagal syncope

  • Group 1
    • While standing
      • May drive and need not notify the DVLA
    • While sitting
      • May drive and need not notify the DVLA if there is an avoidable trigger which will not occur whilst driving.
      • Otherwise must not drive until annual risk of recurrence is assessed as below 20%

Syncope with avoidable trigger or otherwise reversible cause

  • Group 1
    • While standing
      • May drive and need not notify the DVLA
    • While sitting
      • Must not drive for 4 weeks. Driving may resume after 4 weeks only if the cause has been identified and treated. Must notify the DVLA if the cause has not been identified and treated.

Transient loss of consciousness- recurring episodes

Recurrent episodes of TLoC are less common than isolated episodes but the relevance to increased risk in driving cannot be overemphasised.

Recurrent TLoC is most commonly due to recurrent syncope, occurring in around 20% to 30% of patients.

Recurrence of syncope is usually within three years of the first episode, and in over 80% of these cases there has been at least one additional episode within two years of the first episode.

In relation to road safety however, the two most important features of temporary loss of consciousness are:

  • prodrome - are there warning signs sufficient in both nature and duration?
  • posture - do the episodes of TLoC occur while sitting?

A prodrome must allow time for a driver to find a safe place to stop before losing consciousness. A prodrome is reliable if the signs are clear, consistent across all events and provide sufficient duration to find a safe stop, or unreliable if these are absent.

Recurrent pre-syncopal events should be treated (from a licensing point of view) in the same way as recurrent syncope, and should therefore be categorised according to the standards for recurrent syncope.

Licence holders or applicants should be informed that they must notify the DVLA when transient loss of consciousness occurs while sitting

Recurrent typical vasovagal syncope with identifiable consistent prodrome

  • Group 1
    • While standing
      • May drive and need not notify the DVLA
    • While sitting
      • Must not drive and must notify the DVLA. Must not drive until annual risk of recurrence is assessed as below 20%.
      • May drive and need not notify the DVLA if there is an avoidable trigger which will not occur whilst driving.
      • Otherwise must not drive until annual risk of recurrence is assessed as below 20%

Recurrent syncope with avoidable trigger or otherwise reversible cause

  • Group 1
    • While standing
      • May drive and need not notify the DVLA
    • While sitting
      • Must not drive for 4 weeks.
      • Driving may resume after 4 weeks only if the cause has been identified and treated.
      • Must notify the DVLA if the cause has not been identified and treated

For syncope occurring while standing or sitting, the following factors indicate high risk:

  • abnormal ECG
  • clinical evidence of structural heart disease.

Further investigations such as 48-hour ambulatory ECG, echocardiography and exercise testing may be indicated after specialist opinion has been sought.

For more details and most up to date guidance then this must be obtained from the publication "At a Glance Guide to the Current Medical Standards of Fitness to Drive" and the website www.dvla.gov.uk.

Reference:

Last edited 06/2019 and last reviewed 06/2019

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