During a lumbar puncture, nerve fluid is taken from the spinal canal. This examination provides valuable information about a possible change in the composition of the fluid and thus about diseases of the nervous system.
What is a lumbar puncture?
During a lumbar puncture, nerve fluid is removed from the spinal canal. Lumbar puncture is a very important diagnostic tool for clarifying diseases and symptoms. The sample from the cerebrospinal fluid is taken through a small puncture in the spinal canal and examined for composition, cell components and color. The lumbar puncture is performed between the second to fifth lumbar vertebrae or the spinous processes located there. The nerve fluid that is sampled is also known as cerebrospinal fluid, which surrounds the brain and spinal cord. During a lumbar puncture, drugs can be injected into the CSF if necessary, or the pressure of the CSF can be measured. Approximately ten to fifteen millimeters of cerebrospinal fluid are removed from the spinal cord. The task of this clear fluid lies in its protective function: it primarily cushions the spinal cord in the event of shocks. If tumors form in the nervous system or inflammatory diseases, this change is also reflected in the composition of the nerve fluid. Lumbar puncture is one of the most common methods of sampling cerebrospinal fluid.
Function, effect, and goals
Lumbar puncture is performed in the recumbent embryonic position or bent forward in a sitting position. After disinfection and local anesthesia, a flexible puncture needle is used to obtain the sample. The nerve fluid pressure is determined with a riser tube. In healthy humans, the cerebrospinal fluid contains a maximum of four cells per microliter. In bacterial meningitis, the cell count is 1,000 cells per microliter in comparison. Increased protein levels may be due to bleeding in the cavities containing neural fluid and may indicate inflammation due to increased numbers of viruses, bacteria, or inflammatory cells. The level of lactate and glucose may indicate disruption of the blood-liquor barrier, because normally the glucose level is half the amount of glucose in the blood. An elevated lactate level detected on lumbar puncture may indicate tuberculous or bacterial meningitis. Especially when inflammatory and malignant diseases of meninges or the brain itself are suspected, such as multiple sclerosis, encephalitis or meningitis, lumbar puncture provides important markers. Thus, tumor cells, but also leukocytes and bacteria as well as glucose, lactate or free hemoglobin can be detected after bleeding. After collection, the samples are sent to the laboratory, microbiology or pathology for more detailed examination. In therapeutic applications, drugs such as chemotherapeutic agents are administered directly via the spinal fluid in exceptional cases. Because of the blood–brain barrier, it is often easier and more efficient to administer drugs via the spinal cord than via the blood. In addition, lumbar puncture is a way to relieve elevated cerebrospinal fluid pressure in the short term in cases of hydrocephalus or cerebrospinal fluid hypotension syndrome. In anesthesia, lumbar puncture is often performed as lumbar anesthesia, which aims to temporarily inhibit the function of certain nerve segments. It is an important anesthetic procedure for operations in the lower half of the body, such as hip replacement surgery or cesarean section. A lumbar puncture is helpful in determining whether there is bleeding in the brain, Lyme disease, or a tumor in the brain or spinal cord. Lumbar puncture is also an effective means of obtaining clarity about an existing inflammatory change in cases of a possible suspected cancer of the meninges, leukemia and lymphoma. Symptoms such as headache, nausea and vomiting may possibly indicate the increase in intracranial pressure, which is why lumbar puncture is not recommended. This intracranial pressure is triggered by brain tumors, brain hemorrhage or inflammation. The lumbar puncture, which takes about 20 minutes, is also performed on an outpatient basis. The aim of the lumbar puncture is to clarify possible diseases, especially nerve diseases. In the meantime, a lumbar puncture is also advisable in cases of suspected Parkinson’s disease and neurosyphilis, a certain form of syphilis.Lumbar puncture is an important tool in MS diagnosis and is also used therapeutically.
Risks, side effects, and hazards
Lumbar puncture should not be performed if there is a suspected increase in intracranial pressure. Furthermore, there is a contraindication in the case of a blood clotting disorder because of prescribed medications. Lumbar puncture is relatively painless, so local anesthesia is not always performed. A common side effect may be the onset of headache, which is reduced in the recumbent position. Preventive bed rest does not help. The headache usually subsides after a few days. There may be pain at the puncture site and radiating pain. Likewise, nausea and a feeling of dizziness have been reported as possible side effects. Serious complications such as nerve injuries or paralysis as well as infections occur rather rarely as a result of a lumbar puncture. Bleeding from blood vessels that are punctured by mistake is also possible. Other side effects of a lumbar puncture may include symptoms such as neck stiffness, photophobia, or ringing in the ears. Infections at the puncture site can be treated with appropriate ointments and antibiotics. A numb feeling when a nerve is struck may occur and may be an adverse consequence of lumbar puncture. Circulatory problems and respiratory problems, inflammation of the spinal meninges, or bleeding that might occur after a lumbar puncture is performed are more the exception. The blood-brain barrier may be disturbed in certain diseases. In this case, certain blood components then pass into the cerebrospinal fluid. During lumbar puncture, the protein and sugar content of the cerebrospinal fluid can then also be examined and the exact number of white and red blood cells can be determined.