To date, medicine uses several methods of introducing drugs into the patient's body. One of them is intrathecal administration. The second name for this manipulation is endolumbar infusion. Unlike parenteral infusion, this method involves the delivery of a drug directly into the subshell space of the brain. What is intrathecal administration of the drug? What is the peculiarity of this method of drug infusion and how is it carried out in hospitals?
Why administer drugs endolumbally
Drugs are injected into the subarachnoid space after a puncture of the dura mater of the brain. Only a neurosurgeon is entitled to perform this manipulation. Initially, intrathecal administration of drugs was caused by the need for prolonged analgesia and effective hormonal therapy. Anesthetics and corticosteroids are also injected into the epidural space.
The main advantages and disadvantages of the intrathecal method
The main advantages of this method of drug administration are neurosurgeons who consider it possible to provide the maximum concentration of the active substance in the brain tissues and cerebrospinal fluid. In addition, medications that do not penetrate the blood-brain barrier can be administered intrathecally. Thanks to the infusion of the drug directly into the end tank, it is possible to reduce the dosage of the active components and minimize their systemic unsafe effects.
Among the disadvantages of the method, the complex technique of drug administration, which only experienced and highly qualified neurosurgeons possess, is of particular importance. During the procedure, the risk of a possible difference in intracranial pressure is taken into account. The intrathecal route of administration is a way to deliver fluid solutions directly to the brain. Emulsions and suspensions cannot be introduced into the cerebrospinal fluid by this method. Another drawback is the likelihood of brain damage, but subject to the rules for lumbar puncture, the risk is minimal.
With meningitis
The most common reason for manipulation is bacterial meningitis. This is a dangerous condition for which inflammation of the meninges is characteristic. If intrathecal administration is indicated to the patient, what does this mean? Most likely, there is an urgent need for urgent use of antibacterial agents. To accelerate the action of antibiotics and enhance the therapeutic effect, the drugs are injected directly into the cerebrospinal fluid by puncture of the lumbar space.
This procedure is recommended to be carried out only if more than 72 hours have passed since the parenteral infusion of antibiotics, but the patient has not yet improved. If during this period of time the cerebrospinal fluid has not been rehabilitated during therapy, intrathecal administration of antimicrobial drugs is an obligatory step.
What antibiotics can be injected directly into the cerebrospinal fluid
The selection of antibacterial drugs for endolumbar administration under the subarachnoid membrane is based on the variety of the pathogen, its resistance to antibiotics of this group. In bacterial meningitis, several antibacterial drugs are used in the form of a solution for intrathecal administration. What are these medicines? The list of the most effective includes:
- Amikacin;
- Vancomycin
- "Tobramycin";
- "Dioxidine";
- Gentamicin;
- Polymyxin.
One of these drugs can be prescribed before the results of a bacteriological study. In case of symptoms of toxic effects and a decrease in the level of protein in the cerebrospinal fluid, the antibiotic is canceled and another is prescribed.
Solutions that cannot be introduced into the subarachnoid space
Not all antibacterial drugs are allowed to enter the cerebrospinal fluid at the same time as other drugs. For example, a combination of penicillin medications and Polymyxin can lead to fulminant death.
In addition, the endolumbar administration of antibiotics does not eliminate the need for etiotropic treatment, which the patient receives intravenously or intramuscularly. When selecting medicines, the tendency to allergic reactions, the features of specific drugs, are necessarily taken into account.
Before performing a lumbar puncture, the neurosurgeon must assess the degree of cerebral edema in the patient according to the results of an ophthalmoscopy. If swelling is pronounced, intrathecal administration into the end tank will not bring significant results. Moreover, with edema, the risk of damage to brain tissue increases.
The introduction of cytostatics in brain tumors
In the cerebrospinal fluid, endolumbar administration of chemotherapy is allowed in the presence of a number of oncological diseases in patients. These include meningeal carcinomatosis, meningeal lymphoma, neuroleukemia and metastases of tumors of distant organs.
It should not be forgotten that intrathecal administration of chemotherapy sometimes leads to complications. Some cytostatics, once in the subarachnoid space, can provoke a meningeal reaction of varying severity. Its confirmation is the increased protein content with a normal amount of glucose. This violation passes quickly, but in some cases leads to arachnoiditis or myelitis. There is no exact information about the frequency of complications.
Chemotherapy with Methotrexate
This drug is used in the treatment of a number of neurooncological diseases. Intrathecal administration of Methotrexate in a dosage of 0.25 mg of active substance per 1 kg of patient’s body weight begins a week after surgery. This drug, like any other cytostatic, has side effects.
The disadvantage of Methotrexate is its increased toxicity. After endolumbar administration, patients have an increase in edema at the site of surgical treatment and intracranial hypertension. In addition to Methotrexate, another drug that can be injected directly into the subarachnoid space is used - this is Cytosar, which has a similar composition and principle of action. Velcade and Bortezomib are mistakenly considered analogues of these drugs. These chemotherapy drugs must not be introduced into the cerebrospinal fluid. In the instructions for the use of this antitumor agent, the risk of death in case of its intrathecal administration is noted. Chemotherapy with this drug can only be done parenterally.
Preparation for the procedure
Before administering the drugs endolumbally, the doctor must assess the patency of the cerebrospinal fluid after puncture of the hard membrane. To this end, neurosurgeons conduct liquorodynamic tests. This preparatory stage is of particular importance if the patient is diagnosed with tumor or metastatic lesions of the spinal membranes. If the cerebrospinal fluid paths are blocked, medications will not be able to penetrate the lesions by the endolumbar route. In addition, the myelotoxic effect of the drug may increase due to the impossibility of a uniform distribution over the cerebrospinal fluid.
How to administer intrathecal drugs?
The methodology for the use of drugs by pouring them into the subarachnoid space is to perform several stages:
- The dose of the main active drug must be diluted in 2-3 ml of saline (0.9% sodium chloride).
- At the end of the lumbar puncture, performed at the level of the L3-S1 vertebrae (the needle punctures the epidermis, interspinous and yellow ligaments of the vertebral processes and the dura mater), the syringe cannula is rearranged into the puncture needle pavilion.
- It is necessary to draw 5-6 ml of cerebrospinal fluid into the syringe, then inject 2-3 ml of the drug into the cerebrospinal fluid.
- The syringe is then refilled with cerebrospinal fluid and the remaining contents slowly injected.
- The puncture needle is removed.
- If the patient's condition is satisfactory, he is advised not to get out of bed for the next half hour.
Intrathecal Dosage Systems
In order to reduce the spasticity that accompanies some diseases of the brain and spinal cord, special devices are used for endolumbar administration. With the help of a pump and a catheter installed in the end tank, the substance baclofen, better known under the trade name "Lyorezal", is introduced.
The system for intrathecal administration was developed several years ago by Rostov neurosurgeons. Their invention was appreciated by leading Russian experts in the field of neurooncology. Thanks to the development, patients with severe spastic syndrome occurring against the background of malignant lesions of the brain and spinal cord, various injuries, multiple sclerosis, stroke, meningitis, are able to stop the pain and improve the quality of life. Due to severe pain, patients had severe disorders of the musculoskeletal system, secondary irreversible fibrous changes in the joints.
Before the use of intrathecal implantable systems, physiotherapy methods were used in treatment, oral muscle relaxants were used, which had only a partial therapeutic effect.
Treatment of chronic pain with opiates
These systems for endolumbar administration of drugs are also used as palliative care for cancer patients. The presence of severe pain syndrome, which is evaluated on a visual-analogue scale at the level of 60-100%, is the main indication for use as analgesics of opioid drugs ("Morphine"). The system is installed for patients who have reached the age of majority and have provided written consent to use the system.
The operation is performed as follows:
- First, the individual sensitivity of the patient to the "Morphine" administered by the endolumbar pathway is determined. Special equipment with ultrasonic sensors helps to find out whether the microdose of the drug turned out to be effective.
- With a positive test and the absence of contraindications for implantation of the pump, they begin implantation.
- A catheter connected to a programmed pump is injected intrathecally under the skin within the spinal column.
- After installing the system, the doctor proceeds to configure the implanted device (fixes the speed of medication, provides the ability to turn on and off the pump, and also activates the option to urgently add a dose of the drug with increased pain).
The device needs refilling approximately once every several months, which the patient will be notified of: if the drug is over, the intrathecal pump squeaks. Chemotherapy using this system has not yet been conducted, but neurooncologists are already working on this issue.