The Importance Of A Lumbar Puncture

A lumbar punctureA procedure where a needle is placed in the lower part of the spine (the lumbar spine) to access cerebrospinal fluid. (LP) is an invasive procedure. It is part of an extensive workup when a neurological disorder is suspected. Also known as a spinal tapA procedure where a needle is placed in the lower part of the spine (the lumbar spine) to access cerebrospinal fluid., an LP can detect if an infection, bleeding, or an abnormal process (ie: cancer) is occurring in the central nervous system. As part of the Dandy CriteriaCriteria used for diagnosing patients with IIH., the information obtained from an LP is essential to make the diagnosis of IIH and in ruling out another cause that can be treated in another manner. Throughout the course of IIH, it may be necessary to repeat an LP several times to alleviate the high pressure in the brain.

Reasons to perform (indications) or not perform (contraindications) a lumbar puncture:

Image courtesy of REV MED, an online medical education platform for learners in healthcare.

A lumbar puncture is an invasiveinvolving the introduction of instruments or other objects into the body procedure used for diagnostic and therapeutic purposes. It is diagnostic because it can measure pressure in the brain (opening pressure) and the cerebrospinal fluidFluid that is made by specialized cells in the ventricles of the brain. obtained can be analyzed for appearance, and red blood cells, white blood cells, protein, and glucose can be quantified. The results of the CSFFluid that is made by specialized cells in the ventricles of the brain. fluid can detect if there is a viral or bacterial infection and diagnose some autoimmune disorders.

CSF Fluid	Normal	Viral	Bacterial
Opening Pressure	5-20 cm H₂0	Normal or elevated	Elevated
Appearance	Clear	Clear	Turbid
WBC	< 5 and no PMNs*	10-1000	> 100 and > 80% PMNs*
RBC	< 10	Normal (< 10)	Normal (< 10)
Protein	15-45 mg/dL	Elevated >50 mg/dL	Elevated > 50 mg/dL
Glucose	> 60% serum glucose	< 40% serum glucose	> 60% serum glucose

A lumbar puncture is also therapeutic as it helps decrease the pressure in the brain. This is a critical intervention used for idiopathicThe term idiopathic is used when there is no detectable reason for something. intracranial hypertension (IIH), if increased pressure from CSF fluid is causing papilledemaSwelling of the optic nerve that carries visual signals from the eye to the brain. leading to vision loss, debilitating headaches, and a wide range of chronic symptoms. Having CSF removed can help bring the pressure in the brain back to normal and can reverse some of the known signs and symptoms of IIH. It can be performed in an emergent or non-emergent setting depending on symptoms and physical exam findings.

An LP or spinal tapA procedure where a needle is placed in the lower part of the spine (the lumbar spine) to access cerebrospinal fluid. is performed by a trained medical professional such as an emergency medicine physician, a neurologistMedical doctor who diagnoses and treats nonsurgical issues related to the brain and nervous system. , interventional radiologist, or a neurosurgeonMedical doctor who diagnoses and treats surgical issues related to the brain, spine, and nervous system.. As with any other invasiveinvolving the introduction of instruments or other objects into the body procedure, there are risks of a lumbar punctureA procedure where a needle is placed in the lower part of the spine (the lumbar spine) to access cerebrospinal fluid.. Some of these risks can be minimized with proper positioning, the choice of needle, and use of imaging guidance such as ultrasound or fluoroscopy.¹

Images courtesy of REV MED, an online medical education platform for learners in healthcare.

Caution should be used in people with known extremely high pressure in the brain as this procedure can cause a herniationpushing of brain tissue into abnormal locations. An LP should be avoided if a spinal epidural abscess is suspected and in those at risk for bleeding (such as if one has thrombocytopenialow platelet count that causes easy bruising and bleeding or are on blood thinner medications).¹ There are interventions that can be done in those at-risk for bleeding prior to the procedure.

The most common risks of an LP are:

- Back pain (17%)
- Headache (19%)
- Postdural Puncture Headache (PDHP) (9%)²

*Rare risks of an LP are:

- Post-LP infection
- Spinal and subdural cerebral hematoma
- Cerebral Venous Thrombosis²

*Seen in less than 0.01% of a review of 3868 adult patients²

A postdural puncture headache (PDHP) is a challenging complication of a lumbar puncture. It is seen in about 9-11 out of every 100 lumbar punctures performed.³ The symptoms that typically occur are: headache that worsens when sitting upright, photophobiasensitivity to light, neck stiffness, and nausea. The exact reason why these symptoms occur after a lumbar puncture is unknown but it is theorized that a CSFFluid that is made by specialized cells in the ventricles of the brain. leak is occurring into the dural space from that hole that was made from the needle. When there is a CSF leak is greater than the rate of production of CSF, that causes a low pressure in the central nervous system; however, not all patients with a CSF leak have these symptoms.³ Some risk factors that may lead to a PDHP are: female gender, pregnancy, removal of large amounts of CSF, needle size and type, and orientation of bevel of needle.³ Depending on the severity of the symptoms, it will guide the management to treat PDHP that can range from bedrest to an epidural blood patch. PDHP will be discussed in detail in a future article.

By educating yourself with accurate information, you are serving as your own healthcare advocate. This will allow you to actively participate in your medical care and give yourself a sense of control. You do not have to travel on your medical journey alone. Involving family, friends, and others in the IIH community can help empower you to make the difficult medical decisions to come.

Thank you REV MED for allowing us to use their images. You can follow them on Instagram @REV.MED.

For a detailed step-by-step explanation of how a lumbar puncture is performed, please visit Merck Manual’s Professional Version under “How to do lumbar puncture” that contains illustrations and a complete video.

References

Johnson K, Sexton, D. Lumbar puncture: Technique, indications, contraindications, and complications in adults. In: UpToDate. Aminoff M (Ed.). Updated: October 7, 2021. Accessed March 1, 2023.
Engelborghs S, Niemantsverdriet E, Struyfs H, et al. Consensus guidelines for lumbar punctureA procedure where a needle is placed in the lower part of the spine (the lumbar spine) to access cerebrospinal fluid. in patients with neurological diseases. Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring. 2017;8:111-126.
Bateman B, Naida C, Sun-Edelstein C. Post dural puncture headache. In: UpToDate. Crowley M, Goddeau R (eds.). Updated: November 3, 2022. Accessed March 5th, 2023.

Edith Ruiz, PA-C

Edith Ruiz, PA-C is a certified physician assistant with over 14 years of clinical experience, including the care of neurological surgery and bariatric surgery patients. Additionally, she has several years of experience as a medical writer for healthcare companies to help connect patients to medical information.

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