Extrapyramidal system: extrapyramidal disorders

Extrapyramidal system   - a neural network in the central nervous system that does not pass through the corticospinal or pyramidal system, but nevertheless regulates and controls movements. Accordingly, it is part of the motor system. The neural network is formed in such parts of the brain as the variolium bridge and the medulla oblongata, continuing to the spinal cord.

Mentioned as an indirect way to activate motor functions, the extrapyramidal system is primarily involved in controlling the balance, coordination, posture, muscle tone, reflexes. For example, when a person tries to keep a posture (whether he is sitting or standing), then a lot of muscles are coordinated at this moment. This coordination is under the indirect control of extrapyramidal conducting pathways, namely the pre-spinal cord, the tectospinal tract, the reticulospinal tract and the rubospinal tract.

From the point of view of evolution, the extrapyramidal system is the most ancient system of motor activity, which is difficult to describe, in part because of the entanglement of its constituent pathways and feedbacks. However, it may be   Is divided into three systems   Control: cortical indirect pathways, feedback and visual, auditory, vestibular pathways.

Anatomically extrapyramidal system   Consists of clusters of neurons in the brain stem, including the red core, the upper tubercles of the quadruple, the reticular formation, the vestibular nuclei. Large axons of the red nucleus form a rubospinal tract, helping to control the movements of the upper limbs. Vestibular nuclei are connected with the inner ear, spinal cord and cerebellum, thus forming the pre-vertebral-spinal tract for postural regulators of the neck, head, trunk and extremities. The upper tubercles of the quadruple form a tectospinal tract, important for the reflective movements of the head and eyes (as the closure of the eyelids before the foreign body enters the eye). Finally, the reticular formation is responsible for the reticulospinal tract involved in muscular control.

Certain conditions or diseases affect the extrapyramidal system, manifested in violations of muscle tone, posture, reflex disorders. A number of symptoms referred to as extrapyramidal disorders or extrapyramidal symptoms (EPS) are observed as a result of taking neuroleptic drugs that have an effect on the brain and its pathways. Neuroleptics are used in the treatment of psychotic disorders, like schizophrenia, schizoaffective disorder or psychotic depression.

Examples of EPS - akinesis, akathisia, torticollis, dyskinesia, dystonia. Extrapyramidal disorders include "rabbit syndrome," manifested by frequent involuntary rhythmic movements of perioral muscles, which is caused by long-term use of neuroleptics. This syndrome is usually associated with long-term use of drugs such as haloperidol, pimozide, fluphenazine, olanzopine, clozapine, risperidone. Unfortunately, it is not easy to cure. When the patient needs neuroleptic drugs, you can recommend atypical antipsychotics - quetiamine, remoxipride, the reception of which is much less likely to cause "rabbit syndrome."

Extrapyramidal syndrome causes involuntary movements of the muscles or spasms on the face and neck. It develops when the transfer of the neurotransmitter dopamine is not sufficiently regulated. A person may suffer from extrapyramidal syndrome as a result of a craniocerebral injury or Parkinson's disease, but the main reason is an adverse reaction to antipsychotics. Treatment is necessary, otherwise violations will become more complicated over time. Therapy, as a rule, is aimed at identifying and eliminating the causes.