Lumbar puncture is performed in the lumbar area of the lower back. It is also known as spinal tap. Lumbar puncture procedure involves insertion of a needle between two lumbar bones to get a cerebrospinal fluid sample. The spinal cord and the brain are surrounded by the cerebrospinal fluid to protect them from harm.
Lumbar puncture is used in the diagnosis of central nervous system disorders such as multiple sclerosis and Guillain-Barre syndrome, extreme infections like meningitis or cancers of the spinal cord or the brain. In certain cases, lumbar puncture may be employed by doctors to inject chemotherapy medications or anesthetic drugs into the cerebrospinal fluid.
- Doctors may perform a lumbar puncture for:
- Measuring the cerebrospinal fluid pressure
- Collection of the fluid for analysis in a laboratory
- For injecting radioactive substances or dye into the fluid for getting diagnostic images of cerebrospinal fluid’s flow
- For injecting chemotherapy medications, anesthetics or other drugs
- Lumbar puncture information can be used to diagnose:
- Presence of any bleeding in the brain
- Serious viral, fungal or bacterial infections such as syphilis, meningitis and encephalitis
- Some inflammatory disorders of the nervous system like Guillain-Barre syndrome, multiple sclerosis, etc.
- Some cancers that occur in the spinal cord or brain
Lumbar puncture procedure
Before performing a lumbar puncture, the doctor will check the medical history of the patient, conduct blood tests to verify the presence of clotting or bleeding irregularities, and do a physical evaluation. In some cases, the doctor may also advise a CT scan to verify the presence of any inflammation in or around the nervous system.
The doctor will also verify whether the patient is taking any anticoagulant or blood thinning drugs, in addition to the presence of any allergies in the patient to certain medications like local anesthetics.
Lumbar puncture is generally performed at a clinic or a hospital. The patient is asked to wear hospital robes and made to sit in certain special positions. These special stances loosen the back and enlarge the spaces between the vertebrae, which enable the doctor to insert the needle with ease.
During lumbar puncture
- Before the needle is inserted, the puncture site is numbed by injecting a local anesthetic into the lower back. There will be a brief stinging sensation as the local anesthetic is injected.
- A hollow and thin needle is inserted in the lumbar region between the two lower vertebrae, which passes through the spinal membrane into the canal of the spine. This section of the procedure may result in some pressure in the back.
- After the needle is in position, the patient may be asked to slightly alter the stance.
- The pressure of cerebrospinal fluid is measured, then a sample is removed and the pressure is checked again. In certain cases, a drug may be injected.
- The needle is removed, the back is cleaned with an antiseptic soap and then the puncture area is bandaged.
The entire procedure generally lasts for forty five minutes. The doctor may advise the patient to lie down after it is completed.
The sample of cerebrospinal fluid is sent to a laboratory for analysis. The results of the test are generally available a few days after the procedure. On occasions, it may take longer. It’s best to verify the time frame for the results with the health care provider. An explanation of the results should also be sought by the patient, once he/she receives it.
After lumbar procedure:
- The patient should take rest and not engage in strenuous activities. If the job is physically demanding, then one should take leave from work.
- Any pain can be treated with pain killer medications. Consult the doctor for further advice
Lumbar puncture side effects
Lumbar puncture is generally a safe procedure. However, there may be certain side effects of lumbar puncture, which include the following:
- Nearly forty percent of individuals who have gone through a lumbar puncture procedure develop a headache after the procedure. This is due to the leakage of cerebrospinal fluid into adjacent tissues. The headache generally commences either many hours or up to 2 days, after the lumbar puncture procedure. Other symptoms such as dizziness, vomiting and nausea may accompany the headache. The duration for such headaches can vary from a few hours to up to a week or more.
- The individual may experience discomfort, tenderness or pain in the lower back after lumbar puncture. Post-lumbar puncture pain can sometimes radiate to the hind portion of the legs.
- In very rare cases, increased intracranial pressure caused due to the presence of a brain tumor or some other type of lesion that occupies space can result in brainstem compression or herniation after the withdrawal of cerebrospinal fluid sample. One can verify the presence of excessive pressure within the skull by getting an MRI or CT scan of the brain before the lumbar puncture procedure.
- There may be bleeding from the puncture site. In rare cases, bleeding into the epidural space may also occur.