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 look at what these movement disorders are, what types of dyskinesias exist and what are their risk factors.
What are dyskinesias?
Dyskinesias or dyskinesias are movement disorders characterized by excessive movement or abnormal and involuntary movements.
Movement disorders can be classified into two broad groups: rigid hypokinetic syndrome or hypokinetic movements; and hyperkinetic movement disorders or dyskinesias.
Within this last group, that of dyskinesias, it is necessary to indicate different types, each of them with its specific symptoms and characteristics. What they have in common is where this altered movement occurs that typically affects those affected by this disorder: mainly in the head, arms, legs, hands, lips or body. language.
Most dyskinesias are caused by damage to a specific area of the brain called the basal ganglia., A structure in charge of postural control and voluntary movement. While, as we will see later, there is another type of dyskinesia, like tardive dyskinesia, which is caused by the consumption of a certain class of drugs.
Types of dyskinesia
Most dyskinesias are manifested by an excess of abnormal and involuntary movements and mainly include: tremors, chorea, dystonia, ballismus, tics, myoclonus and stereotypes.
Tremors are characterized by being a class of rhythmic and regular oscillating movements, the length, amplitude or duration of which may vary, produced by contractions of agonistic and antagonistic muscles.
The tremors usually subside with action (for example, when the patient eats or writes) and therefore generally does not affect the subject’s daily life as much.
There are two main classifications of tremor. On the one hand, there is the quivering at rest (or static). This is the most common type of tremor and the most common cause is Parkinson’s disease, a disorder that can start with these tremors in a limb (upper or lower). This usually happens with the muscles at rest, relaxed and fully supported.
On the other hand, we have the tremor in action, which occurs with the voluntary movement of the muscle.. In this category we can include the following:
1.1. postural tremor
This tremor occurs when the person holds a position against gravity (For example, extend your arms).
1.2. intentional tremor
it happens during a voluntary movement towards a goal (Like when we scratch our noses) and it usually gets worse the closer we get.
1.3. kinetic tremor
It is associated with any type of voluntary movement (such as opening and closing the eyes or turning the palms up and down).
1.4. Isometric tremor
This usually happens when a muscle voluntarily contracts, without being accompanied by movement. (For example, lifting a weight and holding it with our hands)
1.5. Task-specific tremors
it only happens when specialized and goal-oriented tasks are performed, Such as writing or speaking.
Korea is a hyperkinetic movement disorder or dyskinesia characterized by a constant flow of involuntary, sudden and brief movements, Which can change from one area of the body to another in completely random and unpredictable ways.
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 neurodegenerative disease.
Korea’s intensity varies. Initially, this type of dyskinesia can appear as a movement in which the person wiggles the waist and moves in a semi-intentional manner (generating an impression of restlessness or nervousness in the observer); in more advanced stages, such as in Huntington’s disease, this dyskinesia becomes more evident and in extreme cases, it can even interfere with breathing, Speech or gait, which can result in an absolute handicap for the patient.
Dystonias are dyskinesias characterized by involuntary muscle contractions, resulting in repetitive twisting movements and abnormal postures.
This movement disorder can manifest itself in a number of ways, affecting only one part of the body (focal-type dystonia) or several parts, or spreading throughout the body.
There are primary forms of dystonia, which can be hereditary, in which case they usually start at an early age and become general; and idiopathic forms, which start in adulthood and are usually focal. Secondary forms of dystonia are associated with other movement disorders or changes in the central nervous system.
The severity and type of dystonic movement varies depending on body posture, task at hand, emotional state, or level of consciousness. Some people also suffer from blepharospasm (Involuntary eyelid twitching) and writer’s cramp or writer’s dystonia, which is a feeling of awkwardness while writing, which decreases both the speed and influence of movement.
Ballism is a severe degree and a more violent form of Korea. It usually affects multiple limbs and both sides of the body. Although it usually comes on suddenly, it usually develops over days or weeks.
Most frequent it is that it affects a hemicuerpo (hemibalismo), although of occasional form it can compromise to a single member (monobalismo), to the lateral and inferior members (parabalismo) or, in a testimonial way, to the four extremities (bibalismo) .
This type of dyskinesia tends to go away during sleep, Although hemibalism has been documented during the mild phases of sleep.
The movements produced by this disorder are so violent that they can sometimes lead to death, exhaustion, or damage to the joints or skin.
Tics are movement disorders and dyskinesias usually brief and repetitive, abrupt and stereotypical, which vary in intensity and occur at irregular intervals.
Although they can be suppressed and avoided on purpose and for a varying period of time, when this occurs people experience an internal sense of tension and a growing urge which eventually causes them to be carried away and the tics reappear, followed by more. of a rebound period. with an increase in the frequency of their occurrence.
Myoclonus is a short, rapid, abrupt, jerky movement of varying amplitude. These dyskinesias are usually caused by muscle contractions (positive myoclonus) or sudden inhibitions in muscle tone (negative myoclonus or asterisks).
This type of dyskinesia 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 zone of the corresponding muscle. They usually appear in neurodegenerative diseases such as Alzheimer’s disease or degeneration corticobasal.
They encompass myoclonus which is linked to other movement disorders such as tremors or dystonia, sharing with these similar pathophysiological mechanisms.
This type of myoclonus can have different lesions of the spinal cord. They appear spontaneously and can persist during sleep.
They are extremely rare, but cases have been reported in peripheral nerve damage.
this type of dyskinesias, characterized by repetitive and coordinated contractions, non-propositional (non-specific) and rhythmic, they generate movements that they can suppress by initiating another voluntary motor activity; that is, stereotypes do not prevent the person from performing motor activity but can sometimes interfere with normal tasks if they are very frequent or harmful.
8. Late dyskinesia
Tardive dyskinesias is a type of involuntary and abnormal movement that comes after a minimum of 3 months of use of neuroleptic drugs, Without any other identifiable cause.
This type of dyskinesia includes the abnormal movement of the tongue, lips and jaw, in a combination of gestures such as sucking, sucking and chewing, in a repetitive, irregular and stereotypical manner.
The vast majority of patients ignore the development of tardive dyskinesia, but many people with more severe disorders may have difficulty chewing, dental damage, dysphagia or dysarthria, etc.
Tardive dyskinesia involves the fact that neuroleptic drugs exert, on the one hand, a hypersensitivity effect of dopaminergic receptors, causing motor dysfunctions; and on the other hand, destruction of gabaergic neurons responsible for inhibiting involuntary movements. A third hypothesis would also indicate a release of toxic free radicals as responsible, in part, for the symptoms of this movement disorder.
- Venegas, Pau, Millán, María E. and Miranda, Marcelo. (2003). Late dyskinesia. Chilean Journal of Neuro-Psychiatry, 41 (2), 131-138
- Sanz García, AI and Martín Fernández, MA (1994). Tardive dyskinesia: applications of current knowledge to clinical practice. Spanish Journal of Pathology, 51.