Dyskinesia (or Dyskinesia): Types, Symptoms, Causes And Characteristics
Dyskinesia or dyskinesia is a medical term that refers to abnormal movement uncontrollable and involuntary due to excessive or inappropriate muscle activity
Next, we will see what these movement disorders consist of, what types of dyskinesias exist and what their risk factors are.
Dyskinesias or dyskinesias are movement disorders characterized by excessive movements or abnormal and involuntary movements
Movement disorders can be classified into two large groups: rigid-hypokinetic syndrome or hypokinetic movements; and hyperkinetic movement disorders or dyskinesias.
Within this last group, that of dyskinesias, it is worth pointing out different types, each of them with their specific symptoms and characteristics. What they do have in common is where this alteration of movements that people suffering from this disorder usually present occurs: mainly in the head, arms, legs, hands, lips or tongue.
Most dyskinesias are caused by an injury to a specific area of the brain, called the basal ganglia , a structure responsible for postural control and voluntary movement. Although, as we will see later, there are other types of dyskinesias, such as tardive dyskinesia, caused by the consumption of certain types of medications.
Types of dyskinesia
Most dyskinesias manifest as an excess of abnormal and involuntary movements, and mainly include: tremors, chorea, dystonia, ballismus, tics, myoclonus and stereotypia.
1. Tremors
Tremors are characterized by being a class of rhythmic and regular oscillatory movements, which can vary in length, amplitude or duration, produced by contractions of agonist and antagonist muscles.
Tremors usually subside with action (for example, when the patient eats or writes) and, therefore, it does not usually affect the subject’s daily life as much.
There are two main classifications of tremor. On the one hand, there is tremor at rest (or static) It is the most common type of tremor and the most common cause is Parkinson’s disease, a disorder that can begin with these tremors in an extremity (upper or lower). It usually occurs with muscles at rest, relaxed and fully supported.
On the other hand, we have action tremor, which happens with the voluntary movement of the muscle Within this category, we can include the following:
1.1. Postural tremor
This tremor occurs when the person maintains a position against gravity (for example, extending your arms).
1.2. Intentional tremor
Occurs when making a voluntary movement towards a goal (like when we scratch our nose) and, normally, it tends to get worse when we get close to it.
1.3. Kinetic tremor
It is associated with any type of voluntary movement (such as opening and closing the eyes or turning the palms of the hand up and down).
1.4. Isometric tremor
It usually occurs when a muscle is voluntarily contracted, without being accompanied by a movement (for example, when lifting a weight and holding it with our hands)
1.5. Task-specific tremor
It only happens when specialized tasks are carried out and oriented towards a specific objective like handwriting or speaking.
2. Korea
Chorea is a hyperkinetic movement disorder or dyskinesia characterized by a constant flow of involuntary, sudden, brief movements which can change from one area of the body to another in a completely random and unpredictable way.
There are two groups of choreas: acquired and hereditary. In the first group, the most common causes are usually drugs, stroke, pregnancy and Sydenham’s chorea (a bacterial infection). In the second group, the most common form is Huntington’s disease, an inherited and neurodegenerative condition
The intensity of chorea is variable. Initially, this type of dyskinesia can present as a movement in which the person wiggles and moves semi-intentionally (generating an impression of restlessness or nervousness in the observer); In more advanced stages, such as Huntington’s disease, this dyskinesia becomes more evident and In extreme cases it can even interfere with breathing speech or walking, which could lead to absolute disability for the patient.
3. Dystonia
Dystonias are dyskinesias characterized by involuntary muscle contractions, resulting in repetitive twisting movements and abnormal postures
This movement disorder can manifest itself in various ways, affecting only one part of the body (focal dystonia) or several parts, or generalizing throughout the body.
There are primary forms of dystonia, which can be hereditary, in which case they usually begin at an early age and are generalized; and idiopathic forms, which originate in adulthood and are usually focal. Secondary forms of dystonia are associated with other movement disorders or alterations of the central nervous system.
The severity and type of dystonic movement varies depending on body posture, the task to be performed, emotional state or level of consciousness. Some people also experience blepharospasms (involuntary contractions of the eyelids) and writer’s cramps or writer’s dystonia, which consists of a feeling of clumsiness during writing, which causes both the speed and flow of movement to decrease.
4. Ballism
ballismo is a severe degree and a more violent form of chorea It usually affects multiple extremities and both sides of the body. Although it generally appears suddenly, it usually develops over days or weeks.
The most common thing is that it affects one hemibody (hemibalism), although occasionally it can involve a single limb (monoballism), both lower limbs (parabalism) or, occasionally, all four limbs (biballism).
This type of dyskinesia tends to subside during sleep although hemiballism has been documented during light phases of sleep.
The movements produced by this disorder are so violent that they can sometimes lead the person to death, due to exhaustion or causing joint or skin injuries.
5. Tics
Tics are movement disorders and dyskinesias usually brief and repetitive, abrupt and stereotyped, varying in intensity and arising at irregular intervals
Although they can be suppressed and avoided voluntarily and for a variable period of time, when this occurs, people experience an internal sensation of tension and growing need that causes them to finally have to let go and the tics reappear, followed by a period of time. rebound with an increase in the frequency of their occurrence.
6. Myoclonus
Myoclonus are brief, rapid and abrupt movements, like jerks, and with variable amplitude. These dyskinesias are usually caused by muscle contractions (positive myoclonus) or sudden inhibitions of muscle tone (negative myoclonus or asterixis).
This type of dyskinesias They can be classified according to the structure of the nervous system in which they are generated :
In this type of myoclonus, the movement is preceded by the activation of the cortical representation area of the corresponding muscle. They usually appear in neurodegenerative diseases such as Alzheimer’s or corticobasal degeneration.
Subcortical
They encompass myoclonus that is related to other movement disorders such as tremor or dystonia, sharing similar pathophysiological mechanisms with these.
Spinals
This type of myoclonus can be due to different injuries to the spinal cord They appear spontaneously and can persist during sleep.
Peripheral
They are extremely rare, but cases have been described in peripheral nerve injuries.
7. Stereotypes
This type of dyskinesias, which are characterized by being repetitive, coordinated, non-propositional (that do not have a specific purpose) and rhythmic contractions, generate movements that can be suppressed by initiating another voluntary motor activity ; That is, stereotypies do not prevent the person from carrying out a motor activity but, sometimes, they can interfere with normal tasks if they are very frequent or harmful.
8. Tardive dyskinesia
Tardive dyskinesias are a type of involuntary and abnormal movement that occurs after a minimum of 3 months of use of neuroleptic medications without any other identifiable cause.
This type of dyskinesia includes abnormal movement of the tongue, lips and jaw, in a combination of gestures such as sucking, sucking and chewing, in a repetitive, irregular and stereotyped manner.
The vast majority of patients are not aware of the development of tardive dyskinesia, But many with more serious disorders may have difficulties when chewing, dental damage, dysphagia or dysarthria, etc.
Tardive dyskinesia occurs because neuroleptic medications exert, on the one hand, a hypersensitization effect on dopamine receptors, causing motor dysfunctions; and on the other hand, a destruction of the GABAergic neurons responsible for inhibiting involuntary movements. A third hypothesis would also point to a release of toxic free radicals as responsible, in part, for the symptoms of this movement disorder.
