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  1. Lumbar puncture (LP) is essential for the diagnosis of two treatable but potentially fatal conditions, central nervous system (CNS) infection and subarachnoid hemorrhage (SAH) with a negative computed tomography (CT) scan.

  2. LP can also be helpful in the differential diagnosis of other conditions including CNS malignancy, pseudotumor cerebri, and demyelinating diseases.

  3. Contraindications to LP include skin or soft tissue infection at the puncture site, acute spinal cord or head trauma, uncorrected severe coagulopathy, and brain shift secondary to a space-occupying lesion (SOL) or diffuse cerebral edema.

  4. Ultrasound-guided LPs reduce the risk of a failed or traumatic procedure, the number of needle insertions, and redirections compared to those performed without imaging.

  5. Complications from LP include brain herniation, headache, infection, spinal hematoma, and neurologic compromise.


Percutaneous needle LP was first introduced by Quincke in 1891.1 Since then, LP has become a fundamental method to access cerebrospinal fluid (CSF) in a variety of clinical settings. In the field of critical care, LP is often used to obtain CSF for analysis and to measure the opening pressure of the subarachnoid space. With the advancement of other diagnostic modalities, especially neuroimaging procedures such as CT scans and magnetic resonance imaging (MRI), the numbers of definite indications for LP have been reduced in recent years. However, analysis of CSF remains essential to the diagnosis of two potentially fatal but treatable conditions, which are CNS infections and SAH in patients with a negative CT scan. CSF analysis should always be correlated with history, physical examination findings, and other diagnostic tests. LP allows clinicians to access CSF in a relatively safe manner in the absence of significant contraindications, although on rare occasions harmful or even serious complications may result. This chapter will review the indications, contraindications, technique, and complications of performing LP in adults.


The primary indication for LP is to diagnose or exclude bacterial, viral, fungal, and parasitic infections of the CNS. LP is also an indispensable step in the exclusion of SAH when there is a strong clinical suspicion of SAH and brain imaging is nondiagnostic. In addition, CSF analysis and CSF pressure provide clinically valuable information in the diagnoses of many other noninfectious neurologic conditions such as CNS malignancies, pseudotumor cerebri, and demyelinating diseases including multiple sclerosis and Guillain-Barré syndrome.

CNS Infection

Meningitis refers to inflammation of the meninges and could be either infectious or noninfectious. Noninfectious causes of meningitis will not be discussed in this chapter. From 2003 to 2007, the United States had an estimated 4100 cases, including 500 deaths, of bacterial meningitis per year.2 The annual incidence has declined significantly since the introduction of Haemophilus influenzae type b (Hib) and pneumococcal conjugate vaccines. Despite these vaccines, bacterial meningitis continues to be a serious health threat, as both the morbidity and mortality ...

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