Description, Causes and Risk Factors:
A condition in which there is a constant succession of slow, writhing, involuntary movements of flexion, extension, pronation, and supination of the fingers and hands, and sometimes of the toes and feet. Usually caused by an extrapyramidal lesion.
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 or by Huntington's Disease, 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.
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.
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.
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.
Athetotic movements are slow, writhing and graceful, and affect mainly the arms, hands, legs and feet. People may also experience other atypical movements, such as, chorea, which triggers involuntary jerky, swift movements of the hands and feet.
Athetosis varies from mild to severe motor dysfunction; it is typified by involuntary, unbalanced movements of the muscle with a difficulty in maintaining a symmetrical posture. Motor dysfunction may be limited to a part of body or may occur throughout the body, depending up on the severity of the condition.
The most obvious symptoms are writhing, convoluted movements of the digits. Athetosis may become apparent as early as 18 months from birth. First signs include: difficulty in feeding, spasms, hypotonia, poor sitting balance, hearing loss, speech impairment, and uncontrolled movements of the face, hands, and feet, which aggravates with time, right through adolescence and at times of emotional stress.
The doctor will take a detailed history of the patient and make physical examinations. On the basis of this, he will be able to conclude the diagnosis of the case. Also, he may ask you to carry out certain investigations to understand the exact cause.CT scan and MRI of the brain are recommended to identify the lesions.
It is not possible to cure athetosis completely, prognosis is relatively poor, however, some approaches help manage the condition better and reduce the intensity of the symptoms of athetosis.
Your health care professional will prescribe the necessary medications to manage the jerky, involuntary movements effectively.
In addition, muscle training and psychological counseling are extremely beneficial. Muscle training helps the patient recuperate and get better control over the affected limbs, at least to a certain extent. Psychological counseling is crucial and it helps tackle stress, anxiety and excitement successfully, given that, these are regular triggers. Hence, muscle training and counseling are important aspects of the treatment plan.
Surgery is a treatment option that is used by a number of doctors, though it is fraught with some risks, such as, paralysis of the limb.
NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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