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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.
- 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.
- 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.
- Epilepsy is frequently misdiagnosed.
- Causes of syncope in childhood include:
- 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.
Reflex anoxic seizures in childhood are usually benign such that the child grows out of it.
Further reading and references
Epilepsies: diagnosis and management; NICE Clinical Guideline (October 2019)
STARS; Syncope Trust and Reflex Anoxic Seizures
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.
McLeod KA; Syncope in childhood. Arch Dis Child. 2003 Apr88(4):350-3.
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.
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.