Intrathecal

Intrathecal is a term that refers to structures located within the meninges of the spinal cord or other neural structures.

1. Intrathecal is most often used to describe the administration of drugs or other substances directly into the cerebrospinal fluid by intrathecal injection. In this case, the substance is injected into the subarachnoid space between the dura mater and the arachnoid membrane of the spinal cord. This method makes it possible to achieve high local concentrations of the drug using much lower doses compared to other routes of administration.

2. The term intrathecal can also refer to other structures located within various membranes. For example, an axon or nerve fiber consists of the fiber itself surrounded by sheaths - the endoneurium, perineurium and epineurium. Thus, the structures located inside these membranes can also be called intrathecal or intrathecal.

Intrathecal injection (intrathecal injection) is a method of introducing medications into the membranes of the spinal cord, which are located inside the spinal canal. This method is used to treat various conditions such as pain, inflammation and muscle spasms.

Intrathecal injection allows the drug to be delivered directly to the site of inflammation or pain, bypassing the systemic bloodstream. This allows you to reduce the systemic toxicity of the drug and increase its effectiveness.

However, intrathecal injection can be a dangerous procedure as it can cause spinal cord damage or other complications. Therefore, before performing an intrathecal injection, it is necessary to conduct a thorough examination of the patient and ensure that the procedure is safe.

In addition, intrathecal injections can be used to deliver drugs into nerve fiber sheaths, which can improve nerve conduction and improve nerve function. For example, intrathecal botulinum toxin injection can be used to treat chronic pain due to neurological diseases.

In general, intrathecal injection is an effective treatment for many diseases, but requires careful preparation and procedure.

Infrathecal - intrathecal - (ancient Greek) inside the meninges, located inside the membranes of a particular organ.

Intrathecal agents are characterized by less distribution of the substance in the body. The blood-brain and placental barriers are especially large. The path through the vascular system is quite complex and multi-stage, which determines the slow development of the drug effect and the long duration of its action; a noticeable amount of the drug can reach the target organs quite late, making it difficult to create a sufficient concentration of the drug at the site of its action. Main routes in the body: stomach and small intestine; liver; portal veins of the liver; hepatic vein; systemic blood flow, heart tissue, blood capillaries of the endorphinergic system; adrenal medulla and cerebral circulation. Especially the path through the lymphatic vessels is difficult for many medicinal substances.

Taking into account changes in the trophism of intrathecal drugs (lack of hemoinduction, and often hemodilation), it is believed that a significant part of them (about 40%) passes the blood-brain barrier by passive diffusion. At a free level, the drug, along with the bloodstream, can cross the BBB during diffusion through the so-called perivascular, or periendothelial, filtration layer along microvessels without selective intracellular penetration. Sufficiently intense diffusion occurs as a result of an increase in the permeability of the BBB in conditions of impaired barrier resistance (with shock, cerebral circulatory failure, stroke, sequestration, edema and swelling of the brain), as well as a significant increase in the acidity of the brain environment with an increase in the content of its organic and inorganic ions (metabolic acidosis). With acidosis, the level of Na+, K+, Cl cations decreases, bicarbonates, phosphorylation and the formation of acid phosphates increase; lysosomes and endocytosis are activated; the synthesis of mucopolysaccharides and proteins increases; the detergent properties of alcohol are enhanced. An increase in free-diffusion metabolism in the BBB is observed in those intoxicated with anti-tuberculosis drugs and phenothiazines, with cerebral hypoxia, autologous blood in the brain, bilirubin coma and hepatic coma, after severe operations and trauma, occurring with phenomena of neuronal suffering. In addition, an increase in the permeability of glialemmal connections is detected in pathology in pathological anatomy: exudative processes and tissue dystrophy, atrophy of brain tissue, vasculitis, hemorrhages, brain destruction, gingigroma, proliferative diseases,