Reflex anoxic seizure (RAS) is a paroxysmal, spontaneously resolving, short-lived episode of pronounced bradycardia or transient asystole. It causes relative cerebral ischaemia, thereby inducing an anoxic ‘seizure’ or ‘attack’. A RAS is also referred to as pallid syncope or a white breath-holding attack (Blackmore, 1998; Bower, 1984; Meyer, 2009; Martin et al, 2010).
These events are usually triggered by painful or frightening stimuli causing excessive vagal stimulation and often can be misdiagnosed as epileptic seizures (Appleton, 1993; Hindley et al, 2006; Tidy, 2012). It is estimated that RAS affects up to 0.8% of preschool children (Tidy, 2012). A paramedic team may be requested to attend to a child after an episode of RAS. It is important for the team to remain aware of this relatively common but under-recognised condition. In this article we present a case of a five year old girl who was diagnosed with RAS followed by a discussion of the condition itself. Some practical points are provided which will be helpful in managing children with RAS in the pre-hospital setting.
Case study
A previously healthy five year-old girl was referred from primary care following an episode of a sudden collapse at home. She was transferred to the hospital in an emergency ambulance. The girl had a mild cough and symptoms of an upper respiratory tract infection in the preceding few days.
The girl was at home, making preparations to go to school when she suddenly developed a nose bleed. Her mother went to fetch some tissues and returned within a few seconds to find her collapsed on the floor looking extremely pale, lifeless and unresponsive, without abnormal limb movements observed at the time. The episode lasted less than a minute following which she sat up looking very distressed. After another couple of minutes she began playing once again and seemed unperturbed by the incident.
The girl was then taken to the local hospital where observations were found to be within normal limits. Her heart rate was 110/bpm, respiratory rate was 24/ breaths per minute, oxygen saturation was 98% in air, her blood glucose was 4.5 mmol/L and her paediatric early warning score was 0. Clinical examination showed inflamed tonsils but the rest was essentially normal. She was already taking a course of oral antibiotic prescribed by her GP for this and was advised to complete the course.
A 12-lead electrocardiogram ECG was performed which showed normal signs. She was diagnosed
Reflex anoxic seizure can be misdiagnosed as an epileptic fit. Serious injuries can occur after an episode.
Discussion
Epidemiology
RAS has been known to occur at any age; however, the peak age of occurrence is in children from the ages of six months to two years and RAS also occurs more often in young girls than boys (Appleton, 1993; Desikan et al, 2005; Tidy, 2012). The most commonly noted trigger is a sudden experience of pain or fright (e.g. Trapping a finger in a door or a minor blow to the head). It is important to note, however, that the actual trigger for pain may be trivial and can go completely unnoticed by parents. Other triggers that might provoke RAS include a mild febrile illness; venepuncture; exposure to excessively hot or cold baths; the sight of blood or a toy being snatched away by another child (Roddy, 1983; Appleton, 1993; Blackmore, 1998; Warrington, 2004; Meyer, 2009; Tidy, 2012).
Clinical presentation
Following a painful physical or psychological experience the child may gasp or cry briefly and then lose consciousness. The child will fall down if they were standing (Appleton, 1993; Martin et al, 2010) and will appear very pale and limp. Parents often describe their child as deathly white, ‘looking as though he/she were dead’ (Appleton, 1993; Blackmore, 1999). In addition to this the child may become stiff (tonic) and have jerking of the limbs (clonic) (Meyer, 2009). An episode of RAS is usually brief sometimes lasting less than 15 seconds but can last up to a minute. The recovery is rapid and upward deviation of the eyes as well as urinary incontinence have been reported (Appleton, 1993; Meyer, 2009: Tidy, 2012). After regaining consciousness, the child may feel tired, washed-out and appear unusually emotional for some time. This phase corresponds to the self resolving period of asystole (Appleton, 1993; Meyer, 2009: Warrington, 2004; Tidy, 2012). Prolonged period of unconsciousness have also been known to occur (Meyer, 2009). As the episodes of RAS have no pre-warning signs, minor injuries due to the sudden collapse are not uncommon (Martin et al, 2010). Serious injuries such as skull and limb fractures can also occur due to trauma sustained during the sudden collapse (Paul and Zengeya, 2012).
Differential diagnosis
It is of paramount importance that practitioners take a detailed but focused history as episodes of RAS can easily be misdiagnosed as epilepsy. It has been found that in up to 50% of cases of reported seizures by parents, after a careful re-evaluation of the history these episodes were adjudged to be due to anoxic seizures and not epileptic events (Stephenson, 2001). In a prospective study of 380 children aged less than 16 years—referred with ‘‘fts, faints, and funny turns’, RAS was the main cause for a non-epileptic spell (Hindley et al, 2006). The difference between RAS and an epileptic ft are highlighted in Box 1 (Stephenson, 2001; Hindley et al, 2006; Meyer, 2009; Martin et al, 2010).
| Reflex anoxic seizure | Epileptic fits |
| RAS occurs due to neutrally mediated syncopal event | Epileptic fits occur due to abnormal electrical discharges in the brain |
| An unpleasant physical or psychological event triggers RAS | Epileptic fits are triggered by lack of sleep, extreme tiredness, starvation, illness, etc |
| There are no warning signs before the episode of RAS | Warning signs have been known in certain types of epilepsies |
| Tongue biting does not occur in RAS | Tongue biting has been known to occur with epileptic fits |
| The episodes are short lived and last less than 30 seconds | Epileptic fits may vary from a few seconds to prolonged duration |
| Usually no medicines are necessary to treat RAS | Often anti-epileptic medicines are necessary to control epileptic fits |
| Prognosis is usually good | Prognosis varies depending on the type of epilepsy |
Other differential diagnoses for RAS in a child include (Appleton, 1993; Stephenson, 2001; Martin et al, 2010; Tide, 2012).
Management
The diagnosis is usually made from the history by a paediatrician. An ECG is usually performed with the first episode as part of the initial baseline investigations to rule out cardiac arrhythmias, long QT syndrome, pre-excitation, heart block or ventricular hypertrophy. However, all of these conditions are extremely rare. An EEG (electroencephalogram) is also indicated as a baseline investigation for suspected RAS. The results of both the ECG and EEG will be normal in RAS (Martin et al, 2010; Tide, 2012). Most often the episodes of RAS do not need any treatment and can usually be managed with a simple explanation and reassurance to the child and parents. Parents should be advised to place the child in the recovery position, monitor the child and avoid picking them up during or immediately after the episode. Atropine has been used in some children where frequent episodes of RAS occur (Desikan et al, 2005). In severe cases, pacemaker insertion has been shown to be very effective but this is rarely determined to be necessary (McLeod et al, 1999; Tide 2012). The child usually grows out of RAS but recurrence in later life has also been recorded (Tidy, 2012).
Following the first episode of RAS, the child should be brought to the hospital to allay the considerable amount of anxiety among parents and to rule out other potential causes. In an unconscious child the ABCDE approach should be followed to stabilise the child and arrange for a safe transfer to the hospital. Cardiac massage is rarely necessary (Desikan et al, 2005).
It is important that paramedic teams attending such emergencies refrain from administering anticonvulsant medications such as rectal diazepam as the child may have had a longer episode of RAS or eye-witness may report the event as a convulsion (Martin et al, 2010; Paul and Zengeya, 2012). The JRCLAC (Joint Royal Colleges Service Liaison Committee) 2010 guidelines should be followed when the administration of diazepam is considered.
Subsequent episodes may be managed with reassurance by the paramedic team if the child has recovered from the episode and is judged to be well after the episode. It is equally important that the paramedic team attending the child after an episode of RAS should assess the child thoroughly and actively look for signs of other serious injuries that may have occurred during the episode of RAS (Martin et al, 2010; Paul and Zengeya, 2012).
Reflex anoxic seizure is generally managed by explanation and reassurance. Pacemaker is necessary in a few cases.
Children who may have recurrent episodes of RAS may need a care plan for the nursery or school and the paramedic team may be called to attend emergencies (Cowie, 2007). It is important for parents to request for such a care plan for easy management of episodes in the future.
Conclusion
RAS is common in childhood and follows an unpleasant physical or psychological stimulus. Parents are often extremely worried after the event and will likely need a great deal of reassurance. A focused history usually clinches the diagnosis. Paramedic teams should assess the child and if confident, manage any subsequent episodes in the community. The authors hope this article will help paramedic teams in dealing with a child with a common but often mis-diagnosed and under-recognised condition in childhood.