What is it about ?
A lumbar puncture is a medical examination that involves taking fluid from the spine. This is cerebrospinal fluid or cerebrospinal fluid. It is the fluid that is found in and around the brain and spinal cord.
The main function of this fluid is shock absorption and protection of the brain and spinal cord. This liquid also has other roles such as transporting nutrients and removing waste.
To perform a lumbar puncture, a needle is inserted into the lower back. The doctor will explain the entire procedure to you and make sure that you are sitting or lying down in the correct position. The fluid collected is then analyzed to find the cause of certain conditions and to be able to choose the most appropriate treatment.
When should it be used?
Lumbar puncture is almost always done in the hospital. In emergency situations, it makes it possible to diagnose inflammation of the brain envelopes (meningitis), inflammation of the brain (encephalitis), bleeding between the meninges (subarachnoid hemorrhage) and other infectious or inflammatory diseases of the central nervous system.
A lumbar puncture is usually done when there is a suspicion of multiple sclerosis (MS), a sarcoidosis, a neurological form of Lyme disease (neuroborreliosis) and sometimes in case of suspected tumor.
Contraindications of a lumbar puncture
Lumbar puncture is not indicated in the presence of neurological symptoms. In this case, it is the imaging exams that are recommended as a priority. Even if an increase in pressure in the brain is suspected, a lumbar puncture will not be performed because the procedure may compress the cerebellum. Symptoms of increased pressure in the brain (intracranial hypertension) are morning headaches, vomiting, and decreased consciousness. Intracranial hypertension can also be detected by looking at the back of the eye.
People who take anticoagulants should tell their doctor beforehand that they are taking these medicines. It may be necessary to stop the anticoagulants a few days before the puncture.
Complications related to lumbar puncture
The possible complications of a lumbar puncture are as follows:
- Compression of the cerebellum: this is extremely rare. The person loses consciousness immediately after the puncture or within a few hours.
- Headaches: These are caused by the loss of pressure of the cerebrospinal fluid in the head. This loss of pressure can occur as a result of a leak at the puncture site. Usually, the headache occurs mainly when standing and decreases in intensity when lying down. About 1 in 10 people will have a headache. Patients with a history of headaches or who have multiple sclerosis are more likely to have headaches. Lying down can relieve headaches, but it does not prevent pain. Pain relievers are usually not helpful. If the headache persists, it should primarily be treated in the hospital with a caffeine infusion. Sometimes a “blood patch” is applied: the patient’s blood is then injected into the region surrounding the puncture site.
What does the puncture detect?
The appearance of the cerebrospinal fluid may already give an indication of one or another condition the patient is suffering from. Normally, cerebrospinal fluid is clear and colorless. If it is cloudy, it may indicate bacterial meningitis. Reddish or yellow-red cerebrospinal fluid after centrifugation indicates recent bleeding. And the yellowish cerebrospinal fluid, in which we find white blood cells, is more indicative of an old bleeding. The liquid is then analyzed in the laboratory for the presence of certain cells (red blood cells, white blood cells, etc.), sugar (glucose) and proteins.
Want to know more?
- Lumbar puncture explained to children – plaster
- The spinal and lumbar punctures, here, Where to find on this page of Cliniques St Luc UCL
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