Reflex anoxic seizures
Encyclopedia
Reflex anoxic seizures are a form of syncope
encountered mainly, but not exclusively, in young children. Reflex anoxic seizures are not epileptic
. By definition, a syncope is from the Greek, “a cutting off,” implying an abrupt interruption in the supply of energy to the cerebral cortex
. This is usually a consequence of a reduction in cerebral perfusion by oxygenated blood. It can be a result of either a sudden reduction in the blood flow
to the brain, a drop in the oxygen
content of the blood supplying the brain, or a combination of the two.'Syncope' can have different meanings ranging from transient loss of consciousness, usually accompanied by a decrease or loss in postural tone (the principal manifestations of “simple faints”), to tonic
and myoclonic events and nonepileptic spasm
s.
Numerous types of anoxic seizure
have been described. The best known, if not necessarily the best understood, is the “simple faint
” or vasovagal syncope. At least in infants and children, breath-holding attacks
are also widely recognized as reflex anoxic seizures. Other types include vagovagal syncope
, cardiac syncope (including long QT disorders
, other cardiac arrhythmias, and structural cardiac disease), syncope due to orthostasis, hyperventilation
, compulsive Valsalva maneuver
s, gastroesophageal reflux disease
, and imposed upper airway obstruction (suffocation
). In addition, anoxic seizures are a feature of both hyperekplexia
and familial rectal pain
syndrome. Finally, there are likely to be other types of anoxic seizure or syncope not yet characterized.
Reflex anoxic seizures are a particular type of anoxic seizure , most commonly seen in young children in whom an anoxic seizure or syncope is provoked or precipitated by a noxious stimulus
(hence “reflex
”). Various precipitants have been identified, but the most common is an unexpected bump to the head. Breath-holding attacks have been recognized for centuries. However, it is only relatively recently that their pathophysiology
has begun to be understood, and in consequence, their separation from reflex anoxic seizures has been recognized. Indeed, the distinction between the two may not be complete.
Reflex anoxic seizures occur in otherwise normal children, although there is no reason to suppose that children with disorders such as cerebral palsy
and mental retardation
are protected from them. They usually start in infancy or early childhood
. Presumably because the precipitants to the attacks generally require a degree of mobility, descriptions of reflex anoxic seizures before the age of 6 months are rare. Also, there are many descriptions of attacks starting in later childhood and in adult life, although in such cases, the precipitants tend to be different, for example, involving bloodletting
(Roddy et al. 1983) or dental extractions.
A minor bump to the head is the most commonly reported precipitant. Usually the toddler
trips and falls; the child's caregiver
may hear the bump. Most commonly, the child does not cry, although some parents give descriptions of the child “trying to cry” (Stephenson 1978), or there may be a gasp or a sob
. Syncope rapidly ensues. Indeed the short latency between the stimulus and the attack has been emphasized as an important distinction from the more familiar (at least in older children and adults) vasovagal syncope. The child loses awareness and postural tone, falling to the ground. There may be down-beat nystagmus
. The child is likely to be pale, sometimes described as “deathly white,” which is entirely appropriate given that they are likely to be asystolic
; however, it is important to note that not all children go pale (or at least are perceived as going pale by their caregivers). Doctors have recorded descriptions from parents of “blue or purple lips,” “yellow patches through the blue,” and of no noticeable color change. In some attacks, the child rapidly returns to normal following the limp or pallid phase. However, more usually there is a convulsive phase
. This is usually manifested with tonic stiffening, often amounting to opisthotonus
, and often includes clenching of the jaw and hands. Video recordings of other forms of anoxic seizures (vasovagal syncopes) suggest that there may be marked asymmetry
. Parents may report the eyes to have rolled or to be “popping out of the head.” A few clonic jerks of the limbs or spasms are often noted. Urinary incontinence
is not uncommon. Any initial limpness may be so short that the whole attack is dominated by the convulsive components.
Recovery is often rapid, but usually the child is sleepy after the attack, and there may be persisting pallor
. Doctors reported that the length of the postictal stupor
reflected the duration of the asystole up to a maximum of 3 minutes of stupor
. Some cases recorded took longer to recover.
Although minor bumps to the head are reported as the most common precipitants to reflex anoxic seizures, many other stimuli may also be involved.Doctors emphasized the importance of minor injuries and sudden fright
. They noted that occipital
blows to the head appeared to be particularly provocative. Pain, especially from emotion (surprise
, fear
, annoyance
, frustration
, and excitement
), crying, and fever
were provocative factors. Fever was reported as a provocative factor in 14% of cases. Some cases of fever-induced reflex anoxic seizures are likely to be misdiagnosed as febrile (epileptic) seizures
, as has been emphasized by a number of authors. Many, if not most, cases of venipuncture
fits are reflex anoxic seizures. When one considers the vast range of situations in which a child (or adult) can be surprised, frightened, upset, or merely excited, it is easy to understand how reflex anoxic seizures can occur in special settings, such as bathing and water immersion; in the anesthetic room; when witnessing “blood and gore”; at the dentist office, school, place of worship, or the hairdresser
's; and whilst watching television
.
The precipitants and the manifestations of reflex anoxic seizures may change with age. Hence, in unsteady toddlers, minor bumps to the head are likely to predominate, whist in the older child, adolescent and adult factors such as the sight of blood
or venipuncture are likely to be more relevant. The adult physician is likely to classify such events as vasovagal syncopes rather than as reflex anoxic seizures and indeed progression through reflex anoxic seizures to vasovagal syncope is recognized. In this regard, note that beyond the toddler stage, children with reflex anoxic seizures may report out-of-body experiences with a dream-like quality.
There is considerable variation in the frequency of reflex anoxic seizures. Some subjects undoubtedly only ever have a single attack whilst other well-documented cases have multiple daily attacks. The attacks have been reported to generally reach a peak in frequency towards the end of the first or beginning of the second year of life.
Syncope (medicine)
Syncope , the medical term for fainting, is precisely defined as a transient loss of consciousness and postural tone characterized by rapid onset, short duration, and spontaneous recovery due to global cerebral hypoperfusion that most often results from hypotension.Many forms of syncope are...
encountered mainly, but not exclusively, in young children. Reflex anoxic seizures are not epileptic
Epilepsy
Epilepsy is a common chronic neurological disorder characterized by seizures. These seizures are transient signs and/or symptoms of abnormal, excessive or hypersynchronous neuronal activity in the brain.About 50 million people worldwide have epilepsy, and nearly two out of every three new cases...
. By definition, a syncope is from the Greek, “a cutting off,” implying an abrupt interruption in the supply of energy to the cerebral cortex
Cerebral cortex
The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
. This is usually a consequence of a reduction in cerebral perfusion by oxygenated blood. It can be a result of either a sudden reduction in the blood flow
Blood flow
Blood flow is the continuous running of blood in the cardiovascular system.The human body is made up of several processes all carrying out various functions. We have the gastrointestinal system which aids the digestion and the absorption of food...
to the brain, a drop in the oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
content of the blood supplying the brain, or a combination of the two.'Syncope' can have different meanings ranging from transient loss of consciousness, usually accompanied by a decrease or loss in postural tone (the principal manifestations of “simple faints”), to tonic
Tonic-clonic seizure
Tonic–clonic seizures are a type of generalized seizure that affects the entire brain...
and myoclonic events and nonepileptic spasm
Spasm
In medicine a spasm is a sudden, involuntary contraction of a muscle, a group of muscles, or a hollow organ, or a similarly sudden contraction of an orifice. It is sometimes accompanied by a sudden burst of pain, but is usually harmless and ceases after a few minutes...
s.
Numerous types of anoxic seizure
Anoxic event
Oceanic anoxic events or anoxic events occur when the Earth's oceans become completely depleted of oxygen below the surface levels. Although anoxic events have not happened for millions of years, the geological record shows that they happened many times in the past. Anoxic events may have caused...
have been described. The best known, if not necessarily the best understood, is the “simple faint
Syncope (medicine)
Syncope , the medical term for fainting, is precisely defined as a transient loss of consciousness and postural tone characterized by rapid onset, short duration, and spontaneous recovery due to global cerebral hypoperfusion that most often results from hypotension.Many forms of syncope are...
” or vasovagal syncope. At least in infants and children, breath-holding attacks
Breath-holding spells
Breath holding spells are the occurrence of episodic apnea in children, possibly associated with loss of consciousness, and changes in postural tone....
are also widely recognized as reflex anoxic seizures. Other types include vagovagal syncope
Vagovagal reflex
Vagovagal reflex refers to gastrointestinal tract reflex circuits where afferent and efferent fibers of the vagus nerve coordinate responses to gut stimuli via the dorsal vagal complex in the brain. The vagovagal reflex controls contraction of the gastrointestinal muscle layers in response to...
, cardiac syncope (including long QT disorders
Long QT syndrome
The long QT syndrome is a rare inborn heart condition in which delayed repolarization of the heart following a heartbeat increases the risk of episodes of torsade de pointes . These episodes may lead to palpitations, fainting and sudden death due to ventricular fibrillation...
, other cardiac arrhythmias, and structural cardiac disease), syncope due to orthostasis, hyperventilation
Hyperventilation
Hyperventilation or overbreathing is the state of breathing faster or deeper than normal, causing excessive expulsion of circulating carbon dioxide. It can result from a psychological state such as a panic attack, from a physiological condition such as metabolic acidosis, can be brought about by...
, compulsive Valsalva maneuver
Valsalva maneuver
The Valsalva maneuver or Valsalva manoeuvre is performed by moderately forceful attempted exhalation against a closed airway, usually done by closing one's mouth and pinching one's nose shut...
s, gastroesophageal reflux disease
Gastroesophageal reflux disease
Gastroesophageal reflux disease , gastro-oesophageal reflux disease , gastric reflux disease, or acid reflux disease is chronic symptoms or mucosal damage caused by stomach acid coming up from the stomach into the esophagus...
, and imposed upper airway obstruction (suffocation
Suffocation
Suffocation is the process of Asphyxia.Suffocation may also refer to:* Suffocation , an American death metal band* "Suffocation", a song on Morbid Angel's debut album, Altars of Madness...
). In addition, anoxic seizures are a feature of both hyperekplexia
Hyperekplexia
Hyperekplexia is a neurologic disorder classically characterised by pronounced startle responses to tactile or acoustic stimuli and hypertonia. The hypertonia may be predominantly truncal, attenuated during sleep and less prominent after a year of age...
and familial rectal pain
Rectal pain
Rectal pain is the symptom of pain in the area of the rectum. A number of different causes have been documented.-Anal fissures:Anal fissure is the most common cause of rectal pain...
syndrome. Finally, there are likely to be other types of anoxic seizure or syncope not yet characterized.
Reflex anoxic seizures are a particular type of anoxic seizure , most commonly seen in young children in whom an anoxic seizure or syncope is provoked or precipitated by a noxious stimulus
Noxious stimulus
A noxious stimulus is "an actually or potentially tissue damaging event." It is a prerequisite for nociception, which itself is a prerequisite for nociceptive pain...
(hence “reflex
Reflex
A reflex action, also known as a reflex, is an involuntary and nearly instantaneous movement in response to a stimulus. A true reflex is a behavior which is mediated via the reflex arc; this does not apply to casual uses of the term 'reflex'.-See also:...
”). Various precipitants have been identified, but the most common is an unexpected bump to the head. Breath-holding attacks have been recognized for centuries. However, it is only relatively recently that their pathophysiology
Pathophysiology
Pathophysiology is the study of the changes of normal mechanical, physical, and biochemical functions, either caused by a disease, or resulting from an abnormal syndrome...
has begun to be understood, and in consequence, their separation from reflex anoxic seizures has been recognized. Indeed, the distinction between the two may not be complete.
Reflex anoxic seizures occur in otherwise normal children, although there is no reason to suppose that children with disorders such as cerebral palsy
Cerebral palsy
Cerebral palsy is an umbrella term encompassing a group of non-progressive, non-contagious motor conditions that cause physical disability in human development, chiefly in the various areas of body movement....
and mental retardation
Mental retardation
Mental retardation is a generalized disorder appearing before adulthood, characterized by significantly impaired cognitive functioning and deficits in two or more adaptive behaviors...
are protected from them. They usually start in infancy or early childhood
Early childhood
For the video game rating with a similar age group see ESRBEarly childhood is a stage in human development. It generally includes toddlerhood and some time afterwards. Play age is an unspecific designation approximately within the scope of early childhood.-Education:Infants and toddlers experience...
. Presumably because the precipitants to the attacks generally require a degree of mobility, descriptions of reflex anoxic seizures before the age of 6 months are rare. Also, there are many descriptions of attacks starting in later childhood and in adult life, although in such cases, the precipitants tend to be different, for example, involving bloodletting
Bloodletting
Bloodletting is the withdrawal of often little quantities of blood from a patient to cure or prevent illness and disease. Bloodletting was based on an ancient system of medicine in which blood and other bodily fluid were considered to be "humors" the proper balance of which maintained health...
(Roddy et al. 1983) or dental extractions.
A minor bump to the head is the most commonly reported precipitant. Usually the toddler
Toddler
A toddler is a young child, usually defined as being between the ages of one and three. Registered nurse, midwife and author, Robin Barker, states 'Any time from eight months onwards your baby will begin to realise he is a separate person from you...
trips and falls; the child's caregiver
Caregiver
Caregiver may refer to:* Caregiver or carer - an unpaid person who cares for someone requiring support due to a disability, frailty, mental health problem, learning disability or old age...
may hear the bump. Most commonly, the child does not cry, although some parents give descriptions of the child “trying to cry” (Stephenson 1978), or there may be a gasp or a sob
SOB
Sob is a verb meaning cry.SOB and SoB may refer to:* Seventeen or Bust, a distributed computing project* Special Operations Battalion , an elite unit of the Croatian army* Sobralia, a genus of orchids* Society of Old Brooklynites...
. Syncope rapidly ensues. Indeed the short latency between the stimulus and the attack has been emphasized as an important distinction from the more familiar (at least in older children and adults) vasovagal syncope. The child loses awareness and postural tone, falling to the ground. There may be down-beat nystagmus
Nystagmus
Nystagmus is a condition of involuntary eye movement, acquired in infancy or later in life, that may result in reduced or limited vision.There are two key forms of Nystagmus: pathological and physiological, with variations within each type. Nystagmus may be caused by congenital disorders,...
. The child is likely to be pale, sometimes described as “deathly white,” which is entirely appropriate given that they are likely to be asystolic
Asystole
In medicine, asystole is a state of no cardiac electrical activity, hence no contractions of the myocardium and no cardiac output or blood flow...
; however, it is important to note that not all children go pale (or at least are perceived as going pale by their caregivers). Doctors have recorded descriptions from parents of “blue or purple lips,” “yellow patches through the blue,” and of no noticeable color change. In some attacks, the child rapidly returns to normal following the limp or pallid phase. However, more usually there is a convulsive phase
Convulsion
A convulsion is a medical condition where body muscles contract and relax rapidly and repeatedly, resulting in an uncontrolled shaking of the body. Because a convulsion is often a symptom of an epileptic seizure, the term convulsion is sometimes used as a synonym for seizure...
. This is usually manifested with tonic stiffening, often amounting to opisthotonus
Opisthotonus
Opisthotonus or opisthotonos, from Greek roots, opistho meaning "behind" and tonos meaning "tension", is a state of a severe hyperextension and spasticity in which an individual's head, neck and spinal column enter into a complete "bridging" or "arching" position...
, and often includes clenching of the jaw and hands. Video recordings of other forms of anoxic seizures (vasovagal syncopes) suggest that there may be marked asymmetry
Asymmetry
Asymmetry is the absence of, or a violation of, symmetry.-In organisms:Due to how cells divide in organisms, asymmetry in organisms is fairly usual in at least one dimension, with biological symmetry also being common in at least one dimension....
. Parents may report the eyes to have rolled or to be “popping out of the head.” A few clonic jerks of the limbs or spasms are often noted. Urinary incontinence
Urinary incontinence
Urinary incontinence is any involuntary leakage of urine. It is a common and distressing problem, which may have a profound impact on quality of life. Urinary incontinence almost always results from an underlying treatable medical condition but is under-reported to medical practitioners...
is not uncommon. Any initial limpness may be so short that the whole attack is dominated by the convulsive components.
Recovery is often rapid, but usually the child is sleepy after the attack, and there may be persisting pallor
Pallor
Pallor is a reduced amount of oxyhaemoglobin in skin or mucous membrane, a pale color which can be caused by illness, emotional shock or stress, stimulant use, lack of exposure to sunlight, anaemia or genetics....
. Doctors reported that the length of the postictal stupor
Postictal state
The postictal state is the altered state of consciousness that a person enters after experiencing a seizure. It usually lasts between 5 and 30 minutes, but sometimes longer in the case of larger or more severe seizures and is characterized by drowsiness, confusion, nausea, hypertension, headache or...
reflected the duration of the asystole up to a maximum of 3 minutes of stupor
Stupor
Stupor is the lack of critical cognitive function and level of consciousness wherein a sufferer is almost entirely unresponsive and only responds to base stimuli such as pain. This is often mistaken for delirium and treated with Haldol and or other anti-psychotic drugs...
. Some cases recorded took longer to recover.
Although minor bumps to the head are reported as the most common precipitants to reflex anoxic seizures, many other stimuli may also be involved.Doctors emphasized the importance of minor injuries and sudden fright
Fear
Fear is a distressing negative sensation induced by a perceived threat. It is a basic survival mechanism occurring in response to a specific stimulus, such as pain or the threat of danger...
. They noted that occipital
Occiput
The occiput is the anatomical term for the posterior portion of the head, in insects the posterior part of those head capsule.-Clinical significance:Trauma to the occiput can cause a basilar skull fracture....
blows to the head appeared to be particularly provocative. Pain, especially from emotion (surprise
Surprise (emotion)
Surprise is a brief emotional state experienced as the result of an unexpected event. Surprise can have any valence; that is, it can be neutral/moderate, pleasant, or unpleasant. If a person experiences a very powerful or long lasting surprise, it may be considered shock.-Reality...
, fear
Fear
Fear is a distressing negative sensation induced by a perceived threat. It is a basic survival mechanism occurring in response to a specific stimulus, such as pain or the threat of danger...
, annoyance
Annoyance
Annoyance is an unpleasant mental state that is characterized by such effects as irritation and distraction from one's conscious thinking. It can lead to emotions such as frustration and anger...
, frustration
Frustration
This article concerns the field of psychology. The term frustration does, however, also concern physics. In this context, the term is treated in a different article, geometric frustration....
, and excitement
Psychomotor agitation
Psychomotor agitation is a series of unintentional and purposeless motions that stem from mental tension and anxiety of an individual. This includes pacing around a room, wringing one's hands, pulling off clothing and putting it back on and other similar actions...
), crying, and fever
Fever
Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
were provocative factors. Fever was reported as a provocative factor in 14% of cases. Some cases of fever-induced reflex anoxic seizures are likely to be misdiagnosed as febrile (epileptic) seizures
Febrile seizure
A febrile seizure, also known as a fever fit or febrile convulsion, is a convulsion associated with a significant rise in body temperature...
, as has been emphasized by a number of authors. Many, if not most, cases of venipuncture
Venipuncture
In medicine, venepuncture, venopuncture or venipuncture is the process of obtaining intravenous access for the purpose of intravenous therapy or for blood sampling of venous blood. This procedure is performed by medical laboratory scientists, medical practitioners, some EMTs, paramedics,...
fits are reflex anoxic seizures. When one considers the vast range of situations in which a child (or adult) can be surprised, frightened, upset, or merely excited, it is easy to understand how reflex anoxic seizures can occur in special settings, such as bathing and water immersion; in the anesthetic room; when witnessing “blood and gore”; at the dentist office, school, place of worship, or the hairdresser
Hairdresser
Hairdresser is a term referring to anyone whose occupation is to cut or style hair in order to change or maintain a person's image. This is achieved using a combination of hair coloring, haircutting, and hair texturing techniques...
's; and whilst watching television
Television
Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...
.
The precipitants and the manifestations of reflex anoxic seizures may change with age. Hence, in unsteady toddlers, minor bumps to the head are likely to predominate, whist in the older child, adolescent and adult factors such as the sight of blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
or venipuncture are likely to be more relevant. The adult physician is likely to classify such events as vasovagal syncopes rather than as reflex anoxic seizures and indeed progression through reflex anoxic seizures to vasovagal syncope is recognized. In this regard, note that beyond the toddler stage, children with reflex anoxic seizures may report out-of-body experiences with a dream-like quality.
There is considerable variation in the frequency of reflex anoxic seizures. Some subjects undoubtedly only ever have a single attack whilst other well-documented cases have multiple daily attacks. The attacks have been reported to generally reach a peak in frequency towards the end of the first or beginning of the second year of life.