What are the risks and safety considerations of a lumbar puncture (LP) procedure?

Safety of Lumbar Puncture

Lumbar puncture (LP) is a generally safe procedure with low complication rates in patients with suspected neurological disorders, with less than 1% of patients experiencing serious complaints requiring specialist treatment. 1

Overall Safety Profile

• Large-scale evidence from studies involving >7,000 patients in clinical trials and >30,000 patients in routine clinical practice demonstrates that LP is safe when performed according to guidelines 1
• The largest prospective multicenter feasibility study involving 3,868 patients showed that while 31% reported post-LP complaints, only 0.3% required an epidural blood patch and 0.7% needed hospitalization for monitoring 1
• All patients who experienced complications had complete recovery after treatment 1

Common Adverse Events

Post-Lumbar Puncture Headache (PLPH)

• Incidence of typical post-LP headache ranges from 0.9% to 9.0% 1
• Typically develops within 3 days of the procedure and manifests as an orthostatic headache (worse when upright, better when lying flat) 1, 2
• More than 85% of post-LP headaches resolve without treatment 1
• Severe cases may require an epidural blood patch, which is effective and well-tolerated even in older patients 1

Other Common Adverse Events

• Back pain (reported in 17% of patients in one large study) 3
• Short-term numbness of the legs 1
• Nausea, vomiting, and dizziness 1
• Vasovagal symptoms such as hypotension or syncope (rare) 1

Risk Factors for Complications

Patient-Related Risk Factors

• Younger age (older adults have lower risk of post-LP headache) 1, 2
• Female sex (especially in women ≤40 years of age) 1, 2
• History of headache (increases risk of post-LP headache) 1
• Body mass index ≤25 kg/m² 1
• Fear of the procedure (patients who are "very worried" have higher risk of non-specific headache) 1
• Limited previous experience with LP 1

Procedure-Related Risk Factors

• Use of cutting-bevel needle rather than atraumatic needle 1, 2
• Use of large-bore (≤22 gauge) needle 1, 2
• Multiple LP attempts (risk approximately doubles with 2-4 attempts and increases five-fold with ≥5 attempts) 2
• Active rather than passive withdrawal of CSF 1, 2
• Withdrawal of >30 mL of CSF 1
• Sitting posture during procedure 1

Serious but Rare Complications

• Cerebral and spinal herniation (extremely rare when proper technique and indications are followed) 4, 5
• Infection (rare with proper sterile technique) 6, 5
• Bleeding complications (rare, especially when coagulation status is checked before procedure) 5
• Pneumocephalus and pneumorrachis (extremely rare) 6

Practices That Reduce Risk of Complications

• Use of atraumatic (non-cutting) needles 2, 5
• Smaller gauge needles (balanced with procedure time) 2
• Orientation of the bevel in a transverse plane 2, 5
• Replacement of the stylet before withdrawing the needle 2, 5
• Fewer attempts at dural puncture 2
• Gravity flow removal of CSF rather than active withdrawal 2

Practices Not Proven to Reduce Risk

• Bed rest after LP (systematic reviews show no significant effect on risk of severe post-LP headache) 2
• Reducing the volume of CSF taken 2
• Increased hydration 2
• Caffeine for prevention (though it may help treat PLPH) 2

Contraindications

• Elevated intracranial pressure with evidence of a mass lesion 4
• Space-occupying lesions with mass effects 1
• Coagulopathies (international normalized ratio >1.5 or platelet count <40 × 10⁹/L) 1
• Congenital spine abnormalities 1
• Skin infections at the puncture site 1

Clinical Implications

• LP is particularly safe in older adults with cognitive impairment, with individuals with MCI and dementia having lower risks of complications than those with normal cognitive function 1
• The procedure can be safely performed by properly trained healthcare professionals, regardless of specialty (physicians vs. nurses) 1
• A recent Australian study found that only 10.3% of patients experienced complications, with the majority (8.6%) being minor in severity 7

In conclusion, when performed with proper technique and patient selection, lumbar puncture is a safe diagnostic procedure with manageable risks and a high diagnostic yield.