Spinal Tap and Lumbar Puncture | FAQ
We understand that you may have a lot of questions when you learn that your child needs a lumbar puncture:
- What is it?
- Will my child need to be hospitalized?
- Why does my child need it?
- Will it hurt?
We’ve tried to provide some answers to those questions here, and your child’s doctor can talk more about the test with you when you meet.
Background on the brain and spinal cord — the central nervous system (CNS)
Your child’s central nervous system (CNS) made up of her brain and her spinal cord. It’s responsible for collecting information from and sending information to all parts of her body.
The spinal cord is a long, thin bundle of tissues and cells that extends downward from her brain. It’s nestled in the spinal canal and protected by the vertebrae, just as the brain is protected by the skull.
In the vertebrae, bones are stacked on top of one another and connected by joints, for flexibility. In between are disks that provide cushioning. The disks also create little spaces between the bones, spaces that are covered by a thin membrane. When we perform a lumbar puncture, we go through that thin membrane to get to the spinal canal.
The brain and the spinal cord are also bathed in (and protected by) a fluid produced in the brain called cerebrospinal fluid. This fluid can be useful in diagnosing a condition your child may have.
Frequently asked questions
A lumbar puncture is a common procedure in which we ask your child to curl up in a ball, and then we use a special needle to gain access to her spinal canal through her back. This lets us remove a bit of fluid for testing, deliver medications, or measure/relieve pressure in her spinal canal. This sounds invasive and painful, but while it may feel uncomfortable and some children have headaches afterwards, it feels more like a pinch that lasts a few minutes. Most children have lumbar punctures with local anesthesia, meaning that they’re alert, but the area of the puncture is extremely numb.
Your child’s doctor might request a lumbar puncture in order to:
- take a sample of the cerebrospinal fluid so that it can be examined in a lab
- inject medication (such as anesthesia or chemotherapeutic agents) directly into the CSF, so her body can use it most effectively
- remove excess cerebrospinal fluid (decreasing spinal canal pressure) in children with hydrocephalus or intracranial hypertension
- measure the amount of cerebrospinal fluid pressure in the spinal cord
If your child’s nervous system is damaged, it can cause delays in her normal development and functioning. Early detection means that we have a better chance of identifying the cause, can treat her quickly, and decrease the chance of long-term complications.
Conditions most commonly associated with lumbar punctures include:
- infections such as meningitis (bacterial, viral, parasitic, or fungal)
- lymphoma
- leukemia
- other cancers of the brain or brain system.
- inflammation of the blood vessels (vasculitis)
- auto-immune disorders such as multiple sclerosis
Most often, no special preparation is needed. If your child will have the procedure under sedation, her doctor will give you some preparation guidelines to follow.
Before coming to the hospital, explain to your child what will happen during the test and encourage her to ask questions and express her feelings.
Most children have lumbar punctures with local anesthesia, meaning that they’re alert, but the area of the puncture is extremely numb. Sometimes, we use intravenous (IV) sedation, which makes your child very sleepy. On rare occasions, the procedure is done under general anesthesia, in an operating room. You and your child’s doctors will decide together what is best for your child.
- Once your child is ready for the test, we’ll have her lie on her side and curl up in a tight ball so the physician can access her lower back. A technician or nurse stands beside your child to help her hold still and explains what the physician is doing. Remaining still is very important and will make the test go more smoothly.
- We feel your child's back for a space between the bones of the lower part of the spine to insert the needle. He or she will clean the spot with a special solution, and then apply a numbing cream to your child’s skin.
- We further numb the spot by injecting a special medication. This stings for a few seconds, but it makes the spinal tap less painful. Then, we put the special needle through the numbed skin and into the space where the CSF is found.
- Your child feels some pressure while the needle is being pushed in. It's important she stays still during this time. The cerebrospinal fluid will begin to drip out of the needle and a small amount will be collected in test tubes. We also measure the pressure in her spinal canal.
- If we need to inject medication in the spinal canal, we give it through the same needle after the cerebrospinal fluid is collected.
- We remove the needle and clean and bandage the area on your child’s back.
After the needle is inserted, the doctor attaches a hub with a three-way valve. One opening is connected to a manometer (a little tube that measures pressure). Cerebrospinal fluid rises up the manometer just like mercury or water rises up a barometer in response to atmospheric pressure, and can be measured that way.
About 30 minutes. We also ask that your child lie down immediately afterward here at the hospital for several hours before going home. Please be assured that during and after the test, we do everything we can to make sure she’s as comfortable as possible.
Lumbar punctures usually take place in a doctor’s office — most often a neurologist — that has been equipped to do this procedure.
Your child will be with her doctor or nurse practitioner performing the lumbar puncture, and a nurse or clinical assistant who will help. There may be another doctor in to assist or supervise, too. And parents are always invited to stay, if they think it will be helpful for their child to have them there.
After the test, your child will lie down immediately afterward here at the hospital for several hours before going home. You can read to your child or play quietly with her while she is in bed, and encourage her to drink lots of fluid.
We recommend rest and quiet activities for 24 hours. If your child has a headache, which is fairly common, have her drink lots of fluids and lie down for a few hours.
Most children do very well after a lumbar puncture, but contact your child’s doctor if:
- her headache persists into the next day, and she has been taking it easy and drinking a lot of fluids
- you notice (or your child complains of) anything that may be a neurological concern, such as:
- changes in vision
- unsteadiness on her feet
- significant discomfort at the site of the puncture
- changes in sensation in her legs
This all depends on which tests the lab(s) run. Simple tests are ready the same day, if not within a few hours. If we’re looking for bacteria, we’ll know the results within 72 hours. Other, more demanding tests may be ready in a matter of days or weeks; and specific biochemical tests that are looking for certain antibodies may take six to eight weeks to come back.
Once the results are in, your child’s doctor will explain the lab report to you, and then you’ll discuss next steps together.
We will give your child local numbing medication, so your child won’t feel anything as the needle goes in and out. Sometimes children have an electrical sensation in the leg, which shouldn’t last. Your child’s muscles may feel a little crampy as we have her curl up in a tight ball, but that goes away, too.
No. Lumbar punctures are done in an area of your child’s body that’s below the spinal cord, so there’s no risk of accidentally contacting it.
As with many medical procedures, there’s a risk of infection or bleeding. But we’re very careful, and the risk of infection here at Children’s is extraordinarily low.
Spinal Tap and Lumbar Puncture | Research
Boston Children’s Hospital is home to the world’s most extensive research enterprise at a pediatric hospital. We also have many partnerships with research, biotech, and health care organizations, and we work together to find innovative ways to improve kids’ health.
Avoiding unneeded spinal taps
When babies develop a fever high enough or abrupt enough to cause a seizure, frightened parents often rush them to the emergency room, where their workup frequently includes a spinal tap to rule out bacterial meningitis. Now, in the largest study to date, researchers at Boston Children's find that this procedure is probably not necessary in well-appearing children who have had a simple febrile seizure. Simple febrile seizures — a generalized seizure lasting no more than 15 minutes and not recurring within 24 hours — are common in infants and young children. "We might see at least one case per day in the emergency room," says Amir Kimia, MD, of Boston Children's Department of Emergency Medicine and the study's first author. "When it's a first event, it's pretty scary for parents — they usually call 911."
In the largest study to date, Kimia and colleagues in Boston Children's Emergency Department (ED) reviewed medical charts of 704 babies seen in Boston Children's ED between 1995 and 2006. During that time, they found no cases of bacterial meningitis. Kimia hopes these findings will reassure parents and save babies from unnecessary, invasive testing. Spinal taps requires local anesthesia and often sedation. "It's a safe procedure with an extremely low rate of complications," says Kimia. "But it's a needle and it's not fun. We're trying not to do it unless it's absolutely necessary."
Kimia hopes the findings will reassure anxious parents. "We have a hard time convincing parents in the ER that their child doesn't need a workup," he says. "Some, traumatized by the seizure, are convinced their child was about to die. But if their child is running around in our ER and is smiling and happy, lumbar puncture is probably not indicated."
