Lumbar Puncture: Procedure, Site, Needle Direction, and Structures Pierced

Introduction

Lumbar puncture (LP), also known as a spinal tap, is a medical procedure used to collect cerebrospinal fluid (CSF) for diagnostic and therapeutic purposes. This article explores its procedure, site selection, needle direction, and anatomical structures pierced.

Procedure

A lumbar puncture is performed with the patient in a lateral decubitus position or sitting upright. A sterile technique is used to minimize infection risk.

Site Selection

The procedure is typically performed at the L3-L4 or L4-L5 intervertebral space to avoid damage to the spinal cord, which terminates at the L1-L2 level in adults.

Needle Direction and Structures Pierced

Skin
Subcutaneous tissue
Supraspinous ligament
Interspinous ligament
Ligamentum flavum
Epidural space
Dura mater
Arachnoid mater
Subarachnoid space (where CSF is collected)

Indications of Lumbar Puncture

LP is performed to diagnose infections such as meningitis, subarachnoid hemorrhage, and neurological disorders. It is also used therapeutically in cases like pseudotumor cerebri.

Contraindications

Increased intracranial pressure
Coagulopathy or bleeding disorders
Local infection at the puncture site
Spinal deformities

Conclusion

Lumbar puncture is a crucial diagnostic tool with specific indications and contraindications. Proper technique and site selection are essential to ensure patient safety.