Purpose of a spinal tap
Spinal cord puncture is performed for:
Performing a spinal tap
collecting a small amount of cerebrospinal fluid (CSF). Subsequently, their histology is carried out; measuring the pressure of cerebrospinal fluid in the spinal canal; removing excess cerebrospinal fluid; introducing drugs into the spinal canal; facilitating difficult labor in order to prevent painful shock, as well as as anesthesia before surgery; determining the nature of the stroke; discharge tumor markers; cisternography and myelography.
Using a spinal tap, the following diseases are diagnosed:
bacterial, fungal and viral infections (meningitis, encephalitis, syphilis, arachnoiditis); subarachnoid bleeding (hemorrhages in the brain); malignant tumors of the brain and spinal cord; inflammatory conditions of the nervous system (Guillain-Barre syndrome, multiple sclerosis); autoimmune and dystrophic processes.
Often a spinal tap is equated with a bone marrow biopsy, but this statement is not entirely correct. During a biopsy, a tissue sample is taken for further research. Access to the bone marrow is achieved through a puncture of the sternum. This method allows you to identify bone marrow pathologies, some blood diseases (anemia, leukocytosis and others), as well as metastases in the bone marrow. In some cases, a biopsy can be performed during the puncture process.
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Results ↑
The purpose of a lumbar puncture is to obtain cerebrospinal fluid and its subsequent examination.
Based on the results of a spinal puncture, cerebrospinal fluid is examined, which can be presented in one of four options:
- Bloody: indicates the presence of hemorrhagic processes (initial stage of subarachnoid hemorrhage).
- Yellowish color: due to long-standing hemorrhagic processes (chronic hematomas, meningeal carcinomatosis, blockage of cerebrospinal fluid circulation in the subarachnoid region).
- Grayish-green color: often indicates the presence of brain tumors;
- Clear cerebrospinal fluid is normal.
Norm and pathology
The cerebrospinal fluid undergoes a complete examination:
- CSF pressure is measured;
- the liquid is assessed macroscopically;
- the volume of protein and sugar is determined;
- cell morphologies are examined.
Norm:
- Cerebrospinal fluid color: clear
- Protein content: 150 – 450 mg/l
- Glucose volume: from 60% in blood
- Atypical cells: no
- Leukocytes: up to 5 mm3
- Neutrophils: no
- Red blood cells: no
- The normal liquor pressure is 150-200 water. Art. or 1.5 – 1.9 kPa.
Deviation from the norm may indicate the presence of liquor hypertension.
Besides:
- With various pathologies, red blood cells, neutrophils and pus are detected in the blood.
- The presence of atypical cells may indicate a brain tumor.
- A low glucose value is an indicator of bacterial meningitis.
Photo: malignant cells in the cerebrospinal fluid
What can affect the result?
Unfortunately, the result of a lumbar puncture can be affected by:
- restless position of the patient during the procedure;
- obesity;
- dehydration;
- severe arthritis;
- previous spinal surgeries;
- bleeding into the cerebrospinal fluid;
- With proper puncture, it is impossible to collect cerebrospinal fluid.
Lumbar puncture can be invaluable in diagnosing diseases and infections that are dangerous to the body.
When performed correctly, the procedure is absolutely safe.
Indications for spinal cord puncture
Spinal cord puncture is mandatory for infectious diseases, hemorrhages, and malignant neoplasms.
Inflammatory polyneuropathy
A puncture is taken in some cases for relative indications:
inflammatory polyneuropathy; fever of unknown pathogenesis; demyelinating diseases (multiple sclerosis); systemic connective tissue diseases.
Preparatory stage
Before the procedure, medical workers explain to the patient why the puncture is being performed, how to behave during the procedure, how to prepare for it, as well as possible risks and complications.
Spinal cord puncture requires the following preparation:
Registration of written consent for the manipulation. Submission of blood tests, which evaluate its coagulability, as well as the functioning of the kidneys and liver. Hydrocephalus and some other diseases require computed tomography and MRI of the brain. Collection of information on the history of the disease, recent and chronic pathological processes.
The specialist must be informed about the medications the patient is taking, especially those that thin the blood (Warfarin, Heparin), relieve pain, or have an anti-inflammatory effect (Aspirin, Ibuprofen). The doctor should be aware of existing allergic reactions caused by local anesthetics, anesthesia drugs, iodine-containing agents (Novocaine, Lidocaine, iodine, alcohol), as well as contrast agents.
It is necessary to stop taking blood thinning drugs, as well as analgesics and non-steroidal anti-inflammatory drugs in advance.
Before the procedure, water and food are not consumed for 12 hours.
Women must provide information about their suspected pregnancy. This information is necessary due to the expected x-ray examination during the procedure and the use of anesthetics, which may have an undesirable effect on the unborn child.
Your doctor may prescribe a medication to take before the procedure.
The presence of a person who will be next to the patient is mandatory. A child is allowed to undergo a spinal puncture in the presence of his mother or father.
Technique of the procedure
A spinal cord puncture is performed in a hospital ward or treatment room. Before the procedure, the patient empties his bladder and changes into hospital clothes.
Spinal cord puncture
The patient lies on his side, bends his legs and presses them to his stomach. The neck should also be in a bent position, with the chin pressed to the chest. In some cases, spinal puncture is performed with the patient sitting. The back should be as motionless as possible.
The skin in the puncture area is cleaned of hair, disinfected and covered with a sterile napkin.
The specialist may use general anesthesia or use a local anesthetic. In some cases, a drug with a sedative effect may be used. Also during the procedure, heartbeat, pulse and blood pressure are monitored.
The histological structure of the spinal cord provides for the safest needle insertion between the 3rd and 4th or 4th and 5th lumbar vertebrae. Fluoroscopy allows you to display a video image on a monitor and monitor the manipulation process.
Next, the specialist collects cerebrospinal fluid for further research, removes excess cerebrospinal fluid or injects the necessary drug. The liquid is released without outside help and fills the test tube drop by drop. Next, the needle is removed and the skin is covered with a bandage.
CSF samples are sent for laboratory testing, where histology occurs directly.
Spinal cord cerebrospinal fluid
The doctor begins to draw conclusions based on the nature of the fluid coming out and its appearance. In its normal state, the cerebrospinal fluid is transparent and flows out one drop per second.
At the end of the procedure you must:
compliance with bed rest for 3 to 5 days as recommended by a doctor; keeping the body in a horizontal position for at least three hours; avoiding physical activity.
When the puncture site is very painful, you can resort to painkillers.
Execution technique
The technique is outpatient; if necessary, after it the person can return home, but it is still more often performed during inpatient treatment. The manipulation technique is simple, but requires accuracy and excellent knowledge of anatomy. The main thing is to correctly determine the puncture point. For some diseases of the spine, it is impossible to perform a puncture.
The set of instruments includes a 5 ml syringe, a Beer needle for puncture, sterile tubes for the resulting cerebrospinal fluid, forceps, gloves, cotton balls, sterile diapers, anesthetics, alcohol or chlorhexidine for skin disinfection, and a sterile napkin for sealing the puncture site.
Execution begins with clarification of all the details. The patient is placed on the couch in the fetal position so that the back is arched, this way the spine, all its processes and the spaces between them can be better felt. The area of the future puncture is covered with sterile linen, forming an operating field. The puncture site is treated with iodine, then the iodine is washed off with alcohol, and if necessary, the hair is first removed. Anesthetize the skin and subsequent layers with a local anesthetic and wait for its action.
The needle for spinal puncture (Bira) has a diameter of 2 to 6 mm and a length of 40 to 150 mm. Short and thin needles are used for children; the size for adults is selected according to the person’s constitution. The needles are disposable, made of medical stainless steel, and have a mandrin, or thin metal rod, inside.
The puncture is made layer by layer until it penetrates the spinal canal. CSF begins to leak from the needle, which is held in place by a mandrel. After removing the mandrin, the first step is to measure the pressure of the cerebrospinal fluid - attach a tube with divisions. Normally, the pressure ranges from 100 to 150 mm of water column.
Next, the patency of the arachnoid space is checked: the jugular veins are compressed and pressure is applied to the navel area with a fist. Normally, cerebrospinal fluid pressure during tests increases by 10 or 20 mm of water column.
Liquor is collected in 3 test tubes for general analysis, microbial and biochemical composition.
After removing the needle, you need to lie on your stomach for 2-3 hours, do not lift heavy objects or expose yourself to physical activity. In some cases, it is necessary to remain in bed for up to 3 days.
Indicators determined in liquor
The laboratory studies the following parameters:
- Density – increases with inflammation, decreases with “excess” cerebrospinal fluid, the norm is 1.005–1.008.
- pH is normal from 7.35 to 7.8.
- Transparency - normally the cerebrospinal fluid is transparent, turbidity appears with an increase in leukocytes, the presence of bacteria, and protein impurities.
- Cytosis, or the number of cells in 1 μl - different cells are found for different types of inflammation and infections.
- Protein - the norm is no more than 0.45 g/l, increases in almost all pathological processes.
The level of glucose, lactate, and chlorides is also examined. If necessary, a smear from the cerebrospinal fluid is stained, all cells, their type and stage of development are studied. This is important when diagnosing tumors. Sometimes bacterial culture is performed to determine the sensitivity of bacteria to antibiotics.
Risks
Adverse consequences after spinal cord puncture occur in 1–5 cases out of 1000. There is a risk of:
Intervertebral hernia
axial herniation; meningism (symptoms of meningitis occur in the absence of an inflammatory process); infectious diseases of the central nervous system; severe headache, nausea, vomiting, dizziness. The head may hurt for several days; damage to the roots of the spinal cord; bleeding; intervertebral hernia; epidermoid cyst; meningeal reaction.
If the consequences of the puncture are expressed in chills, numbness, fever, a feeling of tightness in the neck, or discharge at the puncture site, you should immediately consult a doctor.
There is an opinion that during a spinal tap the spinal cord can be damaged. It is erroneous, since the spinal cord is located higher than the lumbar spine, where the puncture is directly made.
Contraindications to spinal cord puncture
Spinal cord puncture, like many research methods, has contraindications. Puncture is prohibited in case of sharply increased intracranial pressure, dropsy or cerebral edema, or the presence of various formations in the brain.
It is not recommended to take a puncture if there are pustular rashes in the lumbar region, pregnancy, impaired blood clotting, taking blood thinning drugs, or ruptured aneurysms of the brain or spinal cord.
In each individual case, the doctor must analyze in detail the risk of the manipulation and its consequences for the life and health of the patient.
It is advisable to contact an experienced doctor who will not only explain in detail why it is necessary to perform a spinal cord puncture, but will also carry out the procedure with minimal risk to the patient’s health.
Hemorrhages
Among the consequences of hemorrhagic nature, the most serious should be considered:
- chronic and acute intracranial subdural hematoma;
- spinal subarachnoid hematoma;
- intracerebral hematoma.
Traumatic damage to the circulatory network can lead to bleeding, especially when the patient in the premorbid period took anticoagulant drugs, diseases of the blood coagulation system, or thrombocytopenia (less than 60 thousand platelets).
