Athetosis

Definition

Definition of Athetosis
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.

Symptoms

Symptoms of Athetosis
The list of signs and symptoms for Athetosis listed below:

1. Slow continuous writhing movements

Causes

Causes of Athetosis
Athetosis is a symptom primarily caused by the marbling, or degeneration of the basal ganglia. 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.

1. 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 nucleus 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.
2. 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 bilirubin 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.
3. Thalamic Stroke: Another study was done where the onset of athetoid movement followed a thalamic stroke. 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.

Diagnosis

Diagnosis of Athetosis
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, hypotonia, 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.

Treatment

Treatment of Athetosis
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:

1. Artane
2. Cogentin
3. Curare, though not practical due to respiratory paralysis
4. Tetrabenazine
5. Haloperidol
6. Thiopropazate
7. Diazepam

Prognosis

Prognosis of Athetosis
Consult with your doctor.

Prevention

Prevention of Athetosis
Consult with your doctor.