Reflexic Anoxic Seizures

Last updated by Peer reviewed by Dr Laurence Knott
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Synonyms: pallid syncopal attack, white breath-holding attacks 

Reflex anoxic seizures are paroxysmal, spontaneously-reversing brief episodes of asystole triggered by pain, fear or anxiety. Anoxic seizures are non-epileptic events caused by a reflex asystole due to increased vagal responsiveness. They are often misdiagnosed as epilepsy.

  • Reflex anoxic seizures occur mainly in young children (infants and preschool children) but can occur at any age[1].
  • Misdiagnosis is common but it is estimated that 0.8% of preschool children are affected.
  • They can occur at any age; however, the peak age group is from 6 months to 2 years[2].
  • Increased vagal tone tends to be familial.
  • During the episode, the child becomes suddenly pale and limp, will fall if standing and loses consciousness.
  • This is followed by stiffening and clonic jerking of the limbs.
  • The episode is usually brief (30-60 seconds) and recovery is rapid.
  • There may also be upward eye deviation and urinary incontinence.
  • On recovery, the child may feel tired and washed-out for some time.
  • Reflex anoxic seizures do not cause tongue-biting and this may be useful in the differentiation from epilepsy.
  • Often diagnosed on the basis of the history and normal electroencephalogram (EEG).
  • ECG: exclude a long QT interval, pre-excitation, heart block or ventricular hypertrophy.
  • Vagal excitation tests, while under continuous EEG and ECG monitoring (ocular compression induces the oculo-cardiac reflex). This procedure is not usually advised or necessary in order to make the diagnosis in children.
  • Reflex anoxic seizures can usually be managed just with reassurance. Drug treatment is usually not needed.
  • Parents should be advised to place the child in the recovery position.
  • Pacemaker insertion is the only definitive treatment and is only used for frequent, severe cases[3, 4].
  • Apart from pacemaker insertion, most other anti-syncope therapies are ineffective.

Editor's note

Dr Sarah Jarvis, 4th June 2021

NICE guidance on epilepsy
The National Institute for Health and Care Excellence (NICE) has updated its guidance on epilepsy[5]. There are no changes in the updated guidance which affect the diagnosis or management of reflexic anoxic seizures.

Reflex anoxic seizures in childhood are usually benign such that the child grows out of it.

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Further reading and references

  1. Cebe L, Singh H; Reflex anoxic seizures (RAS) in an adult patient: a separate entity from epilepsy. BMJ Case Rep. 2018 May 82018. pii: bcr-2017-222389. doi: 10.1136/bcr-2017-222389.

  2. McLeod KA; Syncope in childhood. Arch Dis Child. 2003 Apr88(4):350-3.

  3. Iyer A, Appleton R; Management of reflex anoxic seizures in children. Arch Dis Child. 2013 Sep98(9):714-7. doi: 10.1136/archdischild-2012-303133. Epub 2013 Jun 28.

  4. Sartori S, Nosadini M, Leoni L, et al; Pacemaker in complicated and refractory breath-holding spells: when to think about it? Brain Dev. 2015 Jan37(1):2-12. doi: 10.1016/j.braindev.2014.02.004. Epub 2014 Mar 12.

  5. Epilepsies: diagnosis and management; NICE Clinical Guideline (October 2019 - last updated May 2021)