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Analysis of cerebrospinal fluid

Medical expert of the article

Hematologist, oncohematologist
, medical expert
Last reviewed: 18.10.2021

The study of cerebrospinal fluid (CSF) is the main method of diagnosis, differential diagnosis and evaluation of the effectiveness of treatment of infectious diseases of the central nervous system (CNS). The cerebrospinal fluid for investigation is obtained by puncturing the subarachnoid space of the spinal cord (spinal puncture).

Indications for analysis of cerebrospinal fluid

  • Suspicion of infectious disease of the central nervous system.
  • Evaluation of the effectiveness of its treatment.
  • Endolumbal administration of antibiotics and other medicines.

Contraindications to the analysis of cerebrospinal fluid

Contraindications for spinal puncture: violation of vital functions, convulsive syndrome. In these cases, spinal puncture is performed after restoration of hemodynamics, respiration or transfer of the patient to artificial ventilation of the lungs (IVL), arresting seizures. Considering the exceptional importance of studying cerebrospinal fluid to provide effective care for a patient, with relative contraindications (suspicion of a volumetric process, brain dislocation), in doubtful cases, spinal fluid should be taken out by separate drops without removing the mandrel from the lumen of the needle, in a volume of not more than 2.0 ml .

Preparation for research

The planned study is carried out in the morning on an empty stomach, for emergency indications - at any time of the day.

Methodology of research

The spinal puncture is made with a special puncture needle (Vir's needle) 1.0 and 1.2 mm in diameter, 60.90 and 120 mm long, with a bevel angle of 45 ° and a cone-shaped needle head channel, which makes it easy to remove and insert the mandrane into the lumen needles. Spinal puncture is performed in the patient's position strictly on its side with legs clamped to the abdomen and a bent head. The puncture site is marked with a longitudinal line, applied with a solution of iodine along the spinous processes of the vertebrae from the top to the bottom, and a transverse line connecting the crests of the iliac bones. The place of their intersection corresponds to the gap between vertebrae L 3 and L 4 - most convenient for spinal puncture (puncture between L 4 and L 5 and between L 2 and L 3 is allowed ). Then, the skin around the intended site of the puncture is carefully treated with iodine within a radius of 5 cm and alcohol in a radius of 4 cm. Patients with acute neurologic symptoms are punctured without anesthesia. If necessary, anesthesia of the skin and subcutaneous tissue produced 1-2% solution of novocaine. An additional reference point for specifying the site of the puncture is the protruding spinous process L 4, which is fixed with the thumb of the left hand. The needle is inserted close to the finger, with a slight inclination of the back (30 °), strictly along the middle line, until a sensation of "failure" occurs when piercing the dura mater. After this, the mandril is slowly withdrawn from the lumen of the needle (do not allow spinal fluid to flow out by the stream!), The pressure of the cerebrospinal fluid is measured and sampled for research. After puncture, the patient should lie horizontally on the back for 2 hours without a pillow.

Errors in carrying out spinal puncture

Due to the wrong position of the patient (torso, pelvic rotation), the needle passes the vertebra and does not enter the spinal canal. In this case, it is necessary to check the correctness of the patient's position.

Because of incorrect tilt, the needle rests against the body of the vertebra. It is necessary to check the correct determination of the orientation and inclination of the needle and, after pulling the needle 2-3 cm outwards, repeat the puncture.

If there is no feeling of "failure" of the needle and it rests against the front wall of the spinal canal, pull the needle 1 cm apart and withdraw the mandril from the lumen of the needle.

In rare cases, with a technically correct puncture, a spinal fluid can not be obtained because of the high viscosity of the fluid or pronounced cerebrospinal fluid. In this case, you can try to get the liquid by careful suction with a syringe.

Complications of spinal puncture

  • Traumatization of the vascular plexus of the anterior wall of the spinal canal. In the first drops in the cerebrospinal fluid there is an admixture of blood ("path blood").
  • Touching the spine nerve root (cauda equina), hanging in the lumen of the canal. In this case, there is a reflex contraction of the muscles of the lower limb, the patient experiences a feeling of "electric shock".
  • Convulsions and respiratory disorders due to the dislocation of the brain are extremely rare.

In the first two cases, no special measures are required. In the latter case, it is necessary to inject 5-15 ml of sterile isotonic sodium chloride solution into the spinal canal, withdraw the needle, place the patient on the back with the lowered head end. In the absence of effect - to carry out emergency therapy (IVL, anticonvulsants).

After carrying out spinal puncture

  • Liquorrhea.
  • Post-puncture syndrome (headache, dizziness, nausea, vomiting).

In the case of liquorrhea, it is sufficient to apply a pressure bandage. In post-puncture syndrome should be assigned bed rest, copious drink, drip injection of 0.5 liters of polyionic solution, refrain from the appointment of any diuretics.

Taking a cerebrospinal fluid for examination

The cerebrospinal fluid for the study is collected in three tubes: 2 ml for a general analysis, 2 ml for a biochemical analysis, 1 ml for a bacteriological study in a sterile tube. Two or three drops of liquid for bacteriological examination are applied to a petri dish with a nutrient medium (chocolate agar with polyvayx) and two to three drops into a test tube with a semi-liquid 0.01% agar.

It is also recommended to take 1-2 ml of cerebrospinal fluid in a reserve sterile tube. Before transport to the laboratory, the spinal fluid for general and biochemical examination is stored in a domestic refrigerator, and for microbiological studies - in a thermostat at a temperature of 37 ° C. Transport of cerebrospinal fluid for these purposes must be carried out at the same temperature with the use of thermocouples if necessary.

trusted-source[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]

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