Asterix: what is it, type, associated symptoms and treatment

Asterix is ​​a motor disorder present in various liver, kidney, respiratory, heart and brain disorders.

It manifests as tremors, similar to what a bird does when it flies, and can be caused by many different causes. We will deepen the characteristics of this clinical sign.

    What is the asterisk?

    The asterisk (from the Greek “a” and “sterig”, “do not hold”) is a clinical sign used to describe a neuromuscular disorder consisting of the involuntary occurrence of rhythmic interruptions of muscle contraction, and usually manifests as tremors in the wrist, metacarpophalangeal, and hip joints. This problem usually affects both hands, although it may only affect one in particular.

    This problem is also called a hepatic flap and was first described in 1949 in patients with severe hepatic insufficiency and encephalopathy. These muscle movements are completely involuntary and usually appear when the arms are outstretched and the wrists flexed. Patients affected by this medical condition find it difficult to keep the affected body part stable..

    Although you look like a tremor and often call it that, you actually watched it it is not considered a tremor in the strict sense of the term, but rather repetitive contractions produced by repeated relaxation of muscles engaged in spontaneous movements. However, when a patient is seen with this motor disorder, their physical behavior resembles that of a bird moving its wings, which is why in more common parlance they are called tremors.

    In most cases, this condition develops on the hands, but is not unique to this area. Involuntary throbbing can also be observed in other parts of the human body, such as the eyelids, in the form of tremors on the lips. and tongue or involuntary movement of the ankles and feet would also be signs of asterisks.

      Associated symptoms

      Asterix is ​​a motor disorder whose main symptom is the most visible: involuntary tremors or throbbing of parts of the body, especially in the hands and wrists. This tremor is usually a sudden, irregular movement, with a frequency of 3-5 Hz, that occurs when the person stretches their arms and flexes their wrists. The person has difficulty maintaining a completely fixed position.

      This phenomenon can involve pain in the joints and muscles, as well as weakness and discomfort. As we have seen, other parts of the body can also have a motor impairment that would be considered an asterisk in itself, such as the jaw, tongue, neck and eyelids.

      A patient with asterisks may have other symptoms depending on the cause of the motor disorder. An example is the bilateral asterisk caused by metabolic encephalopathy which usually has very developed symptoms. In this case, this condition can also be accompanied by a mental state due to irregular levels of neurotransmitters circulating in the blood and causing bizarre behavior.

      Although asterisks are a motor condition, they can be accompanied by symptoms such as jaundice (yellowish discoloration of the skin) due to a buildup of bilirubin, swelling or edema of the feet, cramps caused by an electrolyte imbalance and diarrhea which may be accompanied by bleeding. Gum bleeding, blood in the urine, and vomiting of blood (hematemesis) may also occur.

        Types of asterisks

        The causes of a case of asterisks can range from diseased organs to brain damage. Based on this, asterisks are mainly classified into two types.

        1. Bilateral

        Among the most common causes of bilateral asterisks we have Metabolic encephalopathies, especially hepatic and renal.

        Damage to the kidneys and liver is particularly harmful to the body in general and the brain in particular, as improper functioning produces imbalances in the levels of electrolytes and other chemicals in the blood. When organic homeostasis is lost, the brain and other organs stop functioning properly and this can be highlighted as asterisks.

        It is important to stress the specific link between this type of asterisk and the liver and kidneys. These three organs play a very important role in the metabolism of the organism, as they are responsible for eliminating toxic waste from the organism, either by metabolizing and inactivating them, or, directly, by eliminating them from the body. organism by excretion.

        Nitrogen is one of the main wastes produced by the body’s metabolism.. This substance, when not properly eliminated, eventually becomes incorporated into other proteins in the blood and transforms them into aberrant neurotransmitters, causing the peripheral tremors so characteristic of asterisks.

        It should be noted that damage to the liver and kidneys are not the only potential causes of a case of asterisks. Heart and respiratory disease, in addition to substance poisoning, can also be the cause of this type of asterisks.

        2. Unilateral

        The unilateral asterisk it is mainly caused by focal brain damage in the knee region (knee) of the inner capsule and ventrolateral thalamus.

        This is due to the fact that it is in this region that the directly direct nerve fibers exit the cerebral cortex with motor action. Injuries to the midbrain, parietal cortex, and medial frontal cortex can also be causes of unilateral asterisk.

          Associated pathologies

          There are several medical conditions in which we can find asterisks as a symptom, both directly and indirectly related.

          Hepatic encephalopathy is a common condition in patients with cirrhosis. This problem causes brain damage which is accompanied by various psychological changes, such as personality changes and confusion. Added to this, and as we saw in the section on bilateral asterisk, hepatic encephalopathy can cause the characteristic tremors of Asterix.

          Another condition in which this motor disorder can occur is severe respiratory failure. This breathing problem is caused when the lungs have trouble absorbing oxygen and releasing carbon dioxide, causing headaches and a severe loss of reflexes. When the critical point is reached, the asterisk may appear, moment almost immediately before the patient falls into a coma.

          We can also talk about uremic syndrome, a kidney disorder that occurs when there is a dysfunction of the kidneys. As this medical condition worsens, it can result in asterisks as the person gradually loses control of their voluntary motor movement.

          Finally, we have the fact that substance poisoning can lead to this motor disorder. Among the substances that can cause asterisks, we mainly have alcohol and drugs, including barbiturates, carbamazepine, gabapentin, valproate, lithium., ceftazidime, and metoclopramide, all drugs that have this motor disorder as a potential side effect.

          Other diseases and medical conditions that are attributed to possible causes of asterisks that we have:

          • Azotemia
          • Subarachnoid hemorrhage, intracerebral hemorrhage and subdural hematoma
          • Congestive heart failure
          • Wilson’s disease
          • Hypomagnesemia
          • hypokalemia
          • Hypoglycemia

          Asterix treatment

          Treatment for this motor disorder is usually aimed at resolving and correcting the cause or medical condition in which it presented itself as a symptom.. If, for example, what caused the asterisks is a substance, either through intoxication or as a side effect of a drug, treatment would simply recommend that you stop taking that substance or change the doses.

          However, in the event that the cause of these tremors is a more serious medical condition, such as problems with the liver, kidneys or lungs or bleeding in the brain, treatment will depend on the severity of the affected organ and possibilities of being able to intervene. The use of antimioclonic drugs in patients with asterisks is not recommended because these drugs are known to make symptoms worse rather than treating them.

          In case the asterisk is caused by end-stage kidney disease, dialysis is recommended as it may helps filter toxic blood products and to reduce symptomatology, although this method is ineffective in cases where the disease is due to liver damage, and a liver transplant is necessary in these cases.

          Bibliographical references

          • Zackria, Rasiq; John, Savio (2021), “Asterix”, StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 30571066
          • Adams RD, Foley JM. Neurological changes in the most common types of severe liver disease. Trans-American Association of Neurology 1949; 74: pages 217 to 219.

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