Lumbar Puncture

 a)Introduction

    It consists of obtaining cerebrospinal fluid that is performed for the diagnosis of neurological pathology or for therapeutic purposes.

    -Urgent indications: Suspected meningitis, encephalitis or meningoencephalitis, subarachnoid hemorrhage not confirmed by CT.

    -Contraindications: Suspicion of cranial hypertension (decreased level of consciousness, focal neurological deficit)-->Carry out prior CT scan, Skin infection in the puncture area or epidural abscess, Thrombocytopenia <50,000 uL or INR >1.5, Assess treatment to reverse coagulopathy.

b) Technique

1. Inform the patient and obtain verbal consent.
2. Patient position:
1. Lateral decubitus (recommended): In the fetal position, bending the knees towards the abdomen.
2. Sitting: leaning forward.
3. Draw an imaginary line between both iliac crests: intervertebral space L3-L4 (it can also be done between L4-L5).
4. Disinfection of the area and preparation of the sterile field.
5. Local anesthetic infiltration: 1% lidocaine or 2% mepivacaine.
6. Insert the spinal needle (20-22G) with the bevel following the longitudinal line of the back and perpendicular to the skin. It contains a stylet that will be withdrawn to see if liquid comes out. If the needle collides with the bone or acute radicular pain appears: withdraw to the subcutaneous region and redirect caudally.
7. Extract from 10 or 15ml (3-4 sterile tubes with about 10 drops each). Then replace the stylet and withdraw the spinal needle.

c) Complications

• Frequent: Pain in the puncture area, Posterior headache (it is treated with rest, hydration and analgesia).
• Low incidence: paresthesias, infection, bleeding. brain herniation

Bibliografy
1.Engelborghs S, Niemantsverdriet E, Struyfs H, Blennow K, et al. Consensus guidelines for lumbar punture in patients with neurological diseases. Elsevier. 2017;8: 111-26.
2.Uptidate[Internet]. Dsc [uptodate 2018 Jul 2; cited 2020 May 30]. Lumbar punture: Technique, indications, contraindications, and complications in adults.
3.C. Asencio Sánchez, P.González Rodríguez. Médico Interna Residente. ISBN 979-84-18068-36-2