Athetosis
Encyclopedia
Athetosis is a symptom characterized by involuntary convoluted, writhing movements of the fingers, arms, legs, and neck. Movements typical of athetosis are sometimes called athetoid movements. Lesions to the brain are most often the direct cause of the symptoms, particularly to the
corpus striatum. This symptom does not occur alone and is often accompanied by the symptoms of cerebral palsy
, as it is often a result of this disease. Treatments for athetosis are not very effective, and in most cases are simply aimed at the uncontrollable movement, rather than the cause itself.
, spasm
, and involuntary writhing movements of the hands, feet, and face, which progressively worsen through adolescence and at times of emotional distress. Athetosis is caused by lesions in several brain areas such as the hippocampus
and the motor thalamus
, as well as the corpus striatum; therefore children during the developmental age could possibly suffer from cognitive deficits such as speech impairment, hearing loss, and failed or retarded acquirement of sitting balance.
. This degeneration is most commonly caused by complications at birth in addition to rare cases in which the damage may also arise later in life due to stroke or trauma. The two complications of particular interest are intranatal asphyxia
and neonatal jaundice
.
and the putamen
. However, a less-studied consequence of the resulting hypoxia is its effect on the concentrations of the neurotransmitter dopamine within the synapses of neurons in the basal ganglia. Hypoxia
leads to an increase in the extracellular dopamine
levels and therefore, an increase in the activity of the dopaminergic neurons. Furthermore, this increase in extracellular concentration is not caused by an increase in the neurotransmitter synthesis, but instead on inhibiting its reuptake back into the neurons and glial cells. Therefore, there is an increased dopaminergic effect as dopamine remains in the synapse at higher concentrations leading to additional post-synaptic response. As a result, the uncontrollable writhing motions witnessed with athetosis deal with the over-activity of synapses within the basal ganglia.
in the blood. Bilirubin is usually bound to albumin
immediately and sent to the liver. However, in neonatal jaundice, the concentration of bilirubin overwhelms that of albumin and some of the bilirubin remains unconjugated and can enter the brain through the blood-brain barrier. Normally bilirubin would not be able to diffuse across the blood brain barrier, but in infants, the barrier is immature and has higher permeability. Bilirubin is toxic as it prevents the phosphorylation of many proteins, including synapsin I
which binds vesicles in the presynaptic terminal. Therefore it directly inhibits the exocytosis of neurotransmitters and severely hinders the synapses it affects. In autopsies of children who suffered from neonatal jaundice, chronic changes of neuronal loss, gliosis and demyelination were observed in the basal ganglia and more specifically within the globus pallidus.
. The thalamus is part of a pathway that is involved with the cortical feedback loop in which signals from the cortex are relayed through the striatum
, pallidus
and thalamus before making it back to the cortex. The striatum receives excitatory inputs from the cortex and inhibits the pallidum. By doing so it frees the thalamus from pallidal inhibition allowing the thalamus to send excitatory outputs to the cortex. Therefore, the lesions to the thalamus or any other part of this feedback loop can result in movement disorders as they can alter the reactivity of one towards the other. Also, in a case of people with thalamic stroke, a majority suffered severe sensory deficits and ataxia. It is proposed that this loss of proprioception and the ensuing loss of synergic stabilization may also lead to abnormal movements, such as those dealt with in athetosis.
Drugs can also be used in the treatment of athetosis, however their collective effectiveness is not very convincing. There is not a single drug that is a standard among treatment. Many different medicines can be used, including:
Most instances of drug use where the symptoms seem to be lessened tend to be in more mild cases of athetosis.
Treatment by surgical intervention can obviously have the most immediate impact, again however, it is not a cure-all. In patients that have cerebral palsy as the cause of their athetosis, it has been demonstrated that a subthalamotomy
tends to help relieve the extent of athetosis in approximately half of patients. Additionally, late 19th and early 20th century surgical accounts state that athetosis can be relieved by the removal of a part of the cerebral motor cortex
or by cutting a part of the posterior spinal roots. Patients who undergo surgical treatment to relieve the athetosis often see significant improvement in the control of their limbs and digits. While surgery is often very beneficial in the short term and can produce near immediate results, in the long term it has been seen that its effects are not incredibly long lasting.
.
It is also noteworthy that the presence of athetosis in cerebral palsy (as well as other conditions) causes a significant increase in a person’s basal resting metabolic rate. It has been observed that those who have cerebral palsy with athetosis require approximately 500 more Calories per day than their non-cerebral palsy non-athetoid counterpart.
is a movement disorder, very similar to athetosis, in which the symptoms are not differentiable from those of actual athetosis, however the underlying cause is different. While actual athetosis is caused by damage to the brain, specifically in the basal ganglia, pseudoathetosis is caused by the loss of proprioception. The loss in proprioception
is caused by damage to the area between the primary somatosensory cortex and the muscle spindles and joint receptors. Additionally, when observing an MRI, it can be seen that in the brain of a psuetoathetoid patient, lesions on the brain are not seen in the basal ganglia, the area that is oftentimes the cause of athetosis.
disorders that affect the body movement coordination, such as cerebral palsy
. Children may struggle to engage in social communication, since the poor coordination of the tongue and mouth muscles can reduce their speech ability and hinder their social interaction to a greater degree. The caregivers of the affected children are encouraged to closely monitor their nutrition and growth and to provide them with hearing aids in order to relieve their symptoms as well as supporting their academic plans. A growing number of patients is shown to benefit from communication devices such as shorthand typing programs and computer speech devices, as well as simple picture boards.
Patients suffering from the disorder into their adulthood often have trouble being involved in daily activities such as eating, walking, dressing, as well as performing everyday tasks. They are consistently faced with challenges that limit themselves from living on their own. They are more reluctant to be involved in social activities and romantic relationships and more likely to develop poor self-esteem and self-image related to their physical limitations as well as cognitive disabilities, though such habitual thinking is shown to decline when they feel they are accepted and supported by their peers. Patients are also inclined to associate themselves with people who tend not to be engaged in physical activities, according to the September 2008 issue of “Journal of Physical Activity and Health.”
and stroke
.
ing to aid in control.
An additional possible treatment option for those afflicted with the symptom is neurostimulation
. Studies have begun, and in cerebral palsy patients affected with dystonia-choreoathetosis, it has been demonstrated that neurostimulation has been an effective treatment in lessening symptoms in patients. There has not been a tremendous amount of experimentation, though, in this as a possible treatment option.
corpus striatum. This symptom does not occur alone and is often accompanied by the symptoms of 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....
, as it is often a result of this disease. Treatments for athetosis are not very effective, and in most cases are simply aimed at the uncontrollable movement, rather than the cause itself.
Signs
Athetosis can vary from mild to severe motor dysfunction; it is generally characterized by unbalanced, involuntary movements of muscle tone and a difficulty maintaining a symmetrical posture. The associated motor dysfunction can be restricted to a part of body or present throughout the body, depending on the individual and the severity of the symptom. One of the pronounced signs can be observed in the extremities in particular, as the writhing, convoluted movement of the digits. Athetosis can appear as early as 18 months from birth with first signs including difficulty feeding, hypotoniaHypotonia
Hypotonia is a state of low muscle tone , often involving reduced muscle strength. Hypotonia is not a specific medical disorder, but a potential manifestation of many different diseases and disorders that affect motor nerve control by the brain or muscle strength...
, 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...
, and involuntary writhing movements of the hands, feet, and face, which progressively worsen through adolescence and at times of emotional distress. Athetosis is caused by lesions in several brain areas such as the hippocampus
Hippocampus
The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...
and the motor thalamus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...
, as well as the corpus striatum; therefore children during the developmental age could possibly suffer from cognitive deficits such as speech impairment, hearing loss, and failed or retarded acquirement of sitting balance.
Causes
Athetosis is a symptom primarily caused by the marbling, or degeneration of the basal gangliaBasal ganglia
The basal ganglia are a group of nuclei of varied origin in the brains of vertebrates that act as a cohesive functional unit. They are situated at the base of the forebrain and are strongly connected with the cerebral cortex, thalamus and other brain areas...
. This degeneration is most commonly caused by complications at birth in addition to rare cases in which the damage may also arise later in life due to stroke or trauma. The two complications of particular interest are intranatal asphyxia
Asphyxia
Asphyxia or asphyxiation is a condition of severely deficient supply of oxygen to the body that arises from being unable to breathe normally. An example of asphyxia is choking. Asphyxia causes generalized hypoxia, which primarily affects the tissues and organs...
and neonatal jaundice
Neonatal jaundice
Neonatal jaundice or Neonatal hyperbilirubinemia is a yellowing of the skin and other tissues of a newborn infant. A bilirubin level of more than 85 umol/l manifests clinical jaundice in neonates whereas in adults a level of 34 umol/l would look icteric...
.
Asphyxia
Asphyxia directly causes basal ganglia damage due to lack of oxygen and therefore, insufficient nutrient supply. The lesions caused by asphyxia are most prominent on the caudate nucleusCaudate nucleus
The caudate nucleus is a nucleus located within the basal ganglia of the brains of many animal species. The caudate nucleus is an important part of the brain's learning and memory system.-Anatomy:...
and the putamen
Putamen
The putamen is a round structure located at the base of the forebrain . The putamen and caudate nucleus together form the dorsal striatum. It is also one of the structures that comprises the basal ganglia. Through various pathways, the putamen is connected to the substantia nigra and globus pallidus...
. However, a less-studied consequence of the resulting hypoxia is its effect on the concentrations of the neurotransmitter dopamine within the synapses of neurons in the basal ganglia. Hypoxia
Hypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
leads to an increase in the extracellular dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
levels and therefore, an increase in the activity of the dopaminergic neurons. Furthermore, this increase in extracellular concentration is not caused by an increase in the neurotransmitter synthesis, but instead on inhibiting its reuptake back into the neurons and glial cells. Therefore, there is an increased dopaminergic effect as dopamine remains in the synapse at higher concentrations leading to additional post-synaptic response. As a result, the uncontrollable writhing motions witnessed with athetosis deal with the over-activity of synapses within the basal ganglia.
Neonatal jaundice
Neonatal jaundice is the other chief complication that leads to the basal ganglia damage associated with this condition. Jaundice is caused by hyperbilirubinemia, or abnormally high levels of bilirubinBilirubin
Bilirubin is the yellow breakdown product of normal heme catabolism. Heme is found in hemoglobin, a principal component of red blood cells. Bilirubin is excreted in bile and urine, and elevated levels may indicate certain diseases...
in the blood. Bilirubin is usually bound to albumin
Albumin
Albumin refers generally to any protein that is water soluble, which is moderately soluble in concentrated salt solutions, and experiences heat denaturation. They are commonly found in blood plasma, and are unique to other blood proteins in that they are not glycosylated...
immediately and sent to the liver. However, in neonatal jaundice, the concentration of bilirubin overwhelms that of albumin and some of the bilirubin remains unconjugated and can enter the brain through the blood-brain barrier. Normally bilirubin would not be able to diffuse across the blood brain barrier, but in infants, the barrier is immature and has higher permeability. Bilirubin is toxic as it prevents the phosphorylation of many proteins, including synapsin I
Synapsin I
Synapsin I, is the collective name for Synapsin Ia and Synapsin Ib, two nearly identical phosphoproteins that in humans are encoded by the SYN1 gene. In its phosphorylated form, Synapsin I may also be referred to as phosphosynaspin I...
which binds vesicles in the presynaptic terminal. Therefore it directly inhibits the exocytosis of neurotransmitters and severely hinders the synapses it affects. In autopsies of children who suffered from neonatal jaundice, chronic changes of neuronal loss, gliosis and demyelination were observed in the basal ganglia and more specifically within the globus pallidus.
Thalamic stroke
Another study was done where the onset of athetoid movement followed a thalamic strokeStroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
. The thalamus is part of a pathway that is involved with the cortical feedback loop in which signals from the cortex are relayed through the striatum
Striatum
The striatum, also known as the neostriatum or striate nucleus, is a subcortical part of the forebrain. It is the major input station of the basal ganglia system. The striatum, in turn, gets input from the cerebral cortex...
, pallidus
Globus pallidus
The globus pallidus also known as paleostriatum, is a sub-cortical structure of the brain. Topographically, it is part of the telencephalon, but retains close functional ties with the subthalamus - both of which are part of the extrapyramidal motor system...
and thalamus before making it back to the cortex. The striatum receives excitatory inputs from the cortex and inhibits the pallidum. By doing so it frees the thalamus from pallidal inhibition allowing the thalamus to send excitatory outputs to the cortex. Therefore, the lesions to the thalamus or any other part of this feedback loop can result in movement disorders as they can alter the reactivity of one towards the other. Also, in a case of people with thalamic stroke, a majority suffered severe sensory deficits and ataxia. It is proposed that this loss of proprioception and the ensuing loss of synergic stabilization may also lead to abnormal movements, such as those dealt with in athetosis.
Treatments
There are several different treatment approaches to dealing with athetosis. The most common methods are the use of drugs, surgical intervention, and retraining movements of the afflicted person. It is suggested that training a person to relearn movements can be helpful in select situations. Though, generally, this type of treatment will not work, in certain cases it can be found to be very helpful in treating the symptom of athetosis.Drugs can also be used in the treatment of athetosis, however their collective effectiveness is not very convincing. There is not a single drug that is a standard among treatment. Many different medicines can be used, including:
- ArtaneArtaneArtane may refer to:* Artane, Dublin, a suburb of Dublin, Ireland.* Artane Industrial school, an Industrial school in the above suburb.* Artane, a brand-name for the drug trihexyphenidyl used to treat Parkinson's disease....
- Cogentin
- CurareCurareCurare is a common name for various arrow poisons originating from South America. The three main types of curare are:* tubocurare...
, though not very practical - TetrabenazineTetrabenazineTetrabenazine is a drug for the symptomatic treatment of hyperkinetic movement disorder and is marketed under the trade names Nitoman in Canada and Xenazine in New Zealand and some parts of Europe, and is also available in the USA as an orphan drug. On August 15, 2008 the U.S...
- HaloperidolHaloperidolHaloperidol is a typical antipsychotic. It is in the butyrophenone class of antipsychotic medications and has pharmacological effects similar to the phenothiazines....
- ThiopropazateThiopropazateThiopropazate is a typical antipsychotic of the phenothiazine class.- References :...
- DiazepamDiazepamDiazepam , first marketed as Valium by Hoffmann-La Roche is a benzodiazepine drug. Diazepam is also marketed in Australia as Antenex. It is commonly used for treating anxiety, insomnia, seizures including status epilepticus, muscle spasms , restless legs syndrome, alcohol withdrawal,...
Most instances of drug use where the symptoms seem to be lessened tend to be in more mild cases of athetosis.
Treatment by surgical intervention can obviously have the most immediate impact, again however, it is not a cure-all. In patients that have cerebral palsy as the cause of their athetosis, it has been demonstrated that a subthalamotomy
Thalamotomy
First introduced in the 1950s, thalamotomy is an invasive procedure, primarily effective for tremors such as those associated with Parkinson's Disease , where a selected portion of the thalamus is surgically destroyed...
tends to help relieve the extent of athetosis in approximately half of patients. Additionally, late 19th and early 20th century surgical accounts state that athetosis can be relieved by the removal of a part of the cerebral motor cortex
Motor cortex
Motor cortex is a term that describes regions of the cerebral cortex involved in the planning, control, and execution of voluntary motor functions.-Anatomy of the motor cortex :The motor cortex can be divided into four main parts:...
or by cutting a part of the posterior spinal roots. Patients who undergo surgical treatment to relieve the athetosis often see significant improvement in the control of their limbs and digits. While surgery is often very beneficial in the short term and can produce near immediate results, in the long term it has been seen that its effects are not incredibly long lasting.
Choreoathetosis
Chorea is another condition which results from damage to the basal ganglia. Similar to athetosis, it results from mutations affecting the pallidum inhibition of the thalamus as well as increased dopaminergic activity at the level of the striatum. Considering the etiology of both disorders are fairly similar, it comes as no surprise that chorea and athetosis can and usually do occur together in a condition called choreoathetosisChoreoathetosis
Choreoathetosis is the occurrence of involuntary movements in a combination of chorea and athetosis ....
.
Cerebral palsy
Athetosis is a commonly occurring symptom in the disease cerebral palsy. Of all people with the disease, between 16% and 25% of them actually exhibit the symptom of athetosis. A component of this is the finding that most often the symptoms that involve athetosis occur as a part of choreoathetosis as opposed to athetosis alone.It is also noteworthy that the presence of athetosis in cerebral palsy (as well as other conditions) causes a significant increase in a person’s basal resting metabolic rate. It has been observed that those who have cerebral palsy with athetosis require approximately 500 more Calories per day than their non-cerebral palsy non-athetoid counterpart.
Pseudoathetosis
PseudoathetosisPseudoathetosis
Pseudoathetosis is abnormal writhing movements, usually of the fingers, caused by a failure of joint position sense and indicates disruption of the proprioceptive pathway, from peripheral nerve to parietal cortex.-Presentation:...
is a movement disorder, very similar to athetosis, in which the symptoms are not differentiable from those of actual athetosis, however the underlying cause is different. While actual athetosis is caused by damage to the brain, specifically in the basal ganglia, pseudoathetosis is caused by the loss of proprioception. The loss in proprioception
Proprioception
Proprioception , from Latin proprius, meaning "one's own" and perception, is the sense of the relative position of neighbouring parts of the body and strength of effort being employed in movement...
is caused by damage to the area between the primary somatosensory cortex and the muscle spindles and joint receptors. Additionally, when observing an MRI, it can be seen that in the brain of a psuetoathetoid patient, lesions on the brain are not seen in the basal ganglia, the area that is oftentimes the cause of athetosis.
Social implications
Athetosis is characterized as a symptom that is present in many forms of central nervous systemCentral nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
disorders that affect the body movement coordination, 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....
. Children may struggle to engage in social communication, since the poor coordination of the tongue and mouth muscles can reduce their speech ability and hinder their social interaction to a greater degree. The caregivers of the affected children are encouraged to closely monitor their nutrition and growth and to provide them with hearing aids in order to relieve their symptoms as well as supporting their academic plans. A growing number of patients is shown to benefit from communication devices such as shorthand typing programs and computer speech devices, as well as simple picture boards.
Patients suffering from the disorder into their adulthood often have trouble being involved in daily activities such as eating, walking, dressing, as well as performing everyday tasks. They are consistently faced with challenges that limit themselves from living on their own. They are more reluctant to be involved in social activities and romantic relationships and more likely to develop poor self-esteem and self-image related to their physical limitations as well as cognitive disabilities, though such habitual thinking is shown to decline when they feel they are accepted and supported by their peers. Patients are also inclined to associate themselves with people who tend not to be engaged in physical activities, according to the September 2008 issue of “Journal of Physical Activity and Health.”
History
The first noted case of athetosis was discovered by W. A. Hammond and described in his book Diseases of the Nervous System in 1871. Hammond was also the person who created the term “athetosis,” greek for “without fixed position.” In his initial description of athetosis, the extent of the uncontrolled movement was limited to the fingers and toes. In association with this, he noted that the patients' calves and forearms were oftentimes flexed and that movements were generally slow. Over the period of time leading into the late 20th century, the definition of athetosis was expanded to include movements of the neck, tongue, face, and even the trunk. Along with the expansion of the symptoms came the recognition that it was a part of many medical conditions, including cerebral palsyCerebral 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 stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
.
Research directions
As athetosis is relatively difficult to treat, efforts are being made to help those with the condition live and perform tasks more effectively and more efficiently. One such example of work that has been recently undertaken is a project to help those affected with athetosis to use a computer with more ease. Software for the control of the computer uses joysticks that perform linear filterLinear filter
Linear filters in the time domain process time-varying input signals to produce output signals, subject to the constraint of linearity.This results from systems composed solely of components classified as having a linear response....
ing to aid in control.
An additional possible treatment option for those afflicted with the symptom is neurostimulation
Neurostimulation
Neurostimulation involves modulation of the nervous system and electrically activate neurons in the body. The activation of neural elements in a part of the nervous system can be effectively facilitated by stimulation. Micro-electrodes are utilized to interface with excitable tissue in order to...
. Studies have begun, and in cerebral palsy patients affected with dystonia-choreoathetosis, it has been demonstrated that neurostimulation has been an effective treatment in lessening symptoms in patients. There has not been a tremendous amount of experimentation, though, in this as a possible treatment option.