Overview
Definition:
Lumbar puncture (LP), also known as spinal tap, is a diagnostic and therapeutic medical procedure involving the insertion of a needle into the lumbar subarachnoid space to obtain cerebrospinal fluid (CSF) or administer medication
Peri-operative support encompasses all measures taken before, during, and immediately after the procedure to ensure patient safety, comfort, and optimal outcomes.
Epidemiology:
LP is a frequently performed procedure across various medical specialties
Its incidence varies depending on the diagnostic indications, ranging from suspected meningitis and subarachnoid hemorrhage to therapeutic interventions like spinal anesthesia or intrathecal chemotherapy
Understanding peri-operative management is crucial for all residents involved in patient care.
Clinical Significance:
Effective peri-operative support for lumbar puncture is paramount for minimizing complications such as post-dural puncture headache (PDPH), infection, bleeding, and neurological injury
Proper preparation and post-procedure care directly impact patient experience and diagnostic accuracy, aiding in timely and appropriate management of various neurological and systemic conditions.
Indications
Diagnostic Indications:
Suspected meningitis or encephalitis
Evaluation of subarachnoid hemorrhage when CT is negative
Assessment of demyelinating diseases (e.g., Multiple Sclerosis)
Diagnosis of certain autoimmune or paraneoplastic neurological disorders
Detection of malignant cells in CSF (leptomeningeal carcinomatosis)
Evaluation of normal pressure hydrocephalus.
Therapeutic Indications:
Administration of intrathecal chemotherapy
Spinal anesthesia for surgical procedures
Intrathecal injection of medications (e.g., antibiotics, analgesics)
Therapeutic removal of CSF in conditions like idiopathic intracranial hypertension (pseudotumor cerebri) or certain types of hydrocephalus.
Contraindications:
Absolute contraindications include signs of significantly increased intracranial pressure (ICP) with potential for herniation (e.g., focal neurological deficits, papilledema, altered mental status suggestive of mass effect)
Local skin or soft tissue infection at the puncture site
Spinal column deformities that preclude safe needle insertion
Coagulopathy or anticoagulant therapy that cannot be reversed.
Preoperative Preparation
Patient Assessment:
Thorough history to identify risk factors: coagulopathy, anticoagulant use, prior spinal surgery, recent neurological symptoms
Physical examination focusing on neurological status, signs of increased ICP, and local skin integrity
Review of relevant laboratory data: complete blood count (CBC), coagulation profile (PT/INR, aPTT).
Informed Consent:
Detailed explanation of the procedure, its purpose, benefits, risks (including PDPH, infection, bleeding, nerve damage), and alternatives
Address patient concerns and questions
Document consent appropriately.
Patient Positioning:
Lateral decubitus position, with the patient curled on their side, knees drawn to the chest, and chin tucked to the sternum to maximize lumbar intervertebral space
Alternatively, the sitting position with the patient leaning forward over a bedside table, emphasizing spinal flexion.
Equipment Preparation:
Sterile lumbar puncture tray containing: sterile gloves, antiseptic solution (e.g., chlorhexidine or povidone-iodine), sterile drapes, local anesthetic (e.g., lidocaine 1-2%), spinal needles of appropriate gauge (e.g., 20-22 gauge for adults, 22-25 gauge for children) and length, CSF collection tubes (sterile, numbered), manometer for opening pressure measurement if needed, sterile dressings.
Procedural Support During Lp
Aseptic Technique:
Strict adherence to aseptic technique throughout the procedure is crucial to prevent CSF infection
This includes hand hygiene, sterile gloving, and preparing a wide sterile field with antiseptic solution.
Anesthesia And Analgesia:
Local anesthetic infiltration (e.g., 1% lidocaine without epinephrine) of the skin and subcutaneous tissues at the intended puncture site
Adequate waiting time for local anesthetic to take effect
Consider adjunctive analgesia or sedation for anxious patients or children.
Needle Insertion And CSF Collection:
Identify the L3-L4 or L4-L5 interspace (ilÃac crests usually align with L4)
Insert the spinal needle bevel parallel to the dural fibers in the midline or slightly paramedian, advancing slowly
Upon entering the subarachnoid space, CSF will flow
Collect adequate volumes for requested tests (typically 1-2 mL per tube for standard analysis)
Measure opening pressure if indicated.
Monitoring And Patient Comfort:
Continuously monitor the patient for signs of distress, pain, or autonomic changes (e.g., bradycardia, pallor)
Communicate with the patient throughout the procedure, explaining each step
Ensure comfortable positioning and support.
Postoperative Care And Management
Immediate Post Procedure:
After needle removal, apply sterile dressing to the puncture site
Patient is typically kept supine for a period (e.g., 30-60 minutes) to potentially reduce PDPH risk, although evidence for prolonged bed rest is mixed
Encourage fluid intake.
Monitoring For Complications:
Monitor for signs of PDPH (orthostatic headache, nausea, vomiting, photophobia, phonophobia), which typically worsens when upright and improves when supine
Observe for signs of infection (fever, nuchal rigidity, neurological deterioration) or bleeding (neurological deficits, back pain).
Management Of PDPH:
Conservative management: hydration, analgesics (NSAIDs, acetaminophen)
Caffeine citrate (oral or IV) is often effective
If conservative measures fail, consider an epidural blood patch (EBP) performed by an anesthesiologist, which is highly effective
The EBP involves injecting autologous blood into the epidural space near the puncture site to seal the dural leak.
Discharge And Follow Up:
Provide clear post-procedure instructions regarding activity restrictions, signs/symptoms of complications to report, and follow-up appointments
Reinforce the importance of reporting any persistent or worsening symptoms.
Complications
Early Complications:
Post-dural puncture headache (PDPH) is the most common
Other early complications include nausea and vomiting, neck stiffness (usually transient), back pain at the puncture site, and minor bleeding or bruising
Rarely, direct nerve root irritation, vasovagal syncope, or introduction of infection (meningitis, epidural abscess).
Late Complications:
Infection (meningitis, epidural abscess, arachnoiditis) can occur if aseptic technique is breached
Chronic PDPH is rare
Persistent CSF leak, spinal epidural hematoma, or arachnoid cysts are very uncommon sequelae
Increased intracranial pressure due to occult mass lesion can be exacerbated by LP.
Prevention Strategies:
Meticulous aseptic technique is paramount
Use of atraumatic spinal needles (pencil-point or non-cutting tips) may reduce PDPH incidence
Proper patient selection to avoid contraindications
Adequate hydration and post-procedure positioning
Prompt recognition and management of complications, especially PDPH and infection.
Key Points
Exam Focus:
Understand the indications and contraindications for LP, especially relative contraindications like coagulopathy and signs of increased ICP
Mastery of sterile technique and patient positioning is vital
Know the management of PDPH, including conservative measures and epidural blood patch indications and effectiveness.
Clinical Pearls:
Always obtain a coagulation profile if there is any doubt about the patient's hemostatic status
Use the smallest gauge atraumatic needle possible
If the initial attempt fails, repositioning may be more successful than multiple attempts with the same needle
Be aware of the possibility of a "dry tap" and its implications.
Common Mistakes:
Performing LP in the presence of absolute contraindications (e.g., suspected herniation)
Inadequate preparation of the sterile field or breach in aseptic technique
Failure to obtain a proper coagulation profile
Mismanagement of PDPH, leading to prolonged patient suffering
Insufficient CSF volume for analysis.