What are blood patches and what conditions do they treat?

Blood Patches: Purpose and Applications in Medical Practice

Blood patches are procedures that involve injecting a patient's own blood into the epidural space to treat cerebrospinal fluid (CSF) leaks, primarily post-dural puncture headache (PDPH) and spontaneous intracranial hypotension (SIH). 1

What Are Epidural Blood Patches?

• An epidural blood patch (EBP) is a therapeutic procedure that involves injecting autologous blood (the patient's own blood) into the epidural space to seal a dural tear and stop cerebrospinal fluid leakage 2
• The procedure creates a clot that patches the hole in the dura mater, preventing further CSF leakage 1
• EBPs can be performed as either targeted (directed at a specific identified leak site) or non-targeted (performed at a presumed level without precise localization) 1, 3
• The typical volume of blood used ranges from 15-30 mL, depending on the clinical scenario 4

Primary Conditions Treated with Blood Patches

1. Post-Dural Puncture Headache (PDPH)

• PDPH is the most common indication for EBP, occurring as a complication of spinal anesthesia, epidural procedures, or diagnostic lumbar punctures 1
• Characteristics of PDPH include:
  • Postural/orthostatic headache (worse when upright, better when lying flat) 1, 3
  • Onset typically within 5 days of dural puncture 1
  • Often accompanied by neck stiffness and/or auditory symptoms 1, 3
  • Incidence varies from less than 2% to 40% depending on procedural and patient factors 1, 3
• EBP is highly effective for PDPH, with complete relief in approximately 75% of cases and partial improvement in another 18% 4
• EBP should be considered when PDPH symptoms are severe or do not begin to resolve after 2-3 days of conservative management 1, 3

2. Spontaneous Intracranial Hypotension (SIH)

• SIH results from spontaneous CSF leaks in the spine without any known precipitating procedure 1
• Characterized by orthostatic headache similar to PDPH but without a history of dural puncture 1
• First-line treatment is non-targeted EBP, which should be performed as early as possible 1
• If initial EBP fails, myelography is recommended to locate the specific leak site for targeted treatment 1

Effectiveness and Outcomes

• EBP provides complete symptom resolution in approximately 75% of PDPH cases and partial improvement in another 18% 4
• At 24 hours after treatment, headache persists in only 58% of patients receiving EBP compared to 90% with conservative management 5
• By 7 days, only 16% of EBP patients still have headache (mild) versus 86% with conservative treatment 5
• Factors affecting EBP success include:
  • Needle size used in original dural puncture (larger bore needles associated with higher failure rates) 4
  • Timing of EBP (performing within 4 days of puncture may be associated with higher failure rates in some cases) 4

Procedure and Management

• EBP is generally performed under strict aseptic technique, often with fluoroscopic guidance 2
• Conservative management should be attempted first for mild cases, including:
  • Adequate hydration 3
  • Multimodal analgesia (acetaminophen, NSAIDs) 3
  • Caffeine (maximum 900 mg/day in the first 24 hours) 3
• Relief from EBP typically occurs within 4 hours of the procedure 3
• In cases of failure, a repeat EBP may be considered 6

Complications and Considerations

• EBP is generally safe but can rarely be associated with serious complications 2
• Potential complications include:
  • Transient increase in intracranial pressure 2
  • Back pain at injection site 1
  • Rare but serious complications such as infection, hematoma, or nerve damage 1
• Contraindications include fever, local infection, coagulopathy, and patient refusal 2

Special Populations

• In patients with COVID-19, pharmacological approaches should be tried first, but EBP can be considered for severe PDPH, weighing the risks of neurological complications from untreated PDPH against theoretical risks of injecting potentially viremic blood 1
• In obstetric patients, EBP failure rates may be higher, often requiring multiple patches 6

Blood patches represent a highly effective intervention for CSF leaks, particularly for PDPH and SIH, with high success rates and relatively low complication rates when performed properly.