Epidural blood patch

Epidural blood patch is a treatment option for patients with craniospinal hypotension or post-lumbar puncture headaches. The procedure can be done blind or under fluoroscopic or CT guidance, and is performed predominantly by radiologists and anaesthetists. 

Indications

• craniospinal hypotension including post-lumbar puncture headache and spontaneous intracranial hypotension

Contraindications

• allergy to any of the planned medications
• local or systemic infection

Procedure

Epidural blood patches can be targeted (i.e. preprocedural imaging has demonstrated the site of CSF leak - see craniospinal hypotension) or non-targeted ².

Cannulation

At the beginning of the procedure, sterile venous cannulation (e.g. antecubital) is performed, the cannula connected to an extension tube (kept sterile) and flushed. 

Epidural access

Interlaminar approach

Interlaminar access to the spinal epidural space can be done under fluoroscopy or CT, and is essentially identical to one described in the article on lumbar interlaminar epidural injection.

Transforaminal approach

In cases where non-targeted or interlaminar blood-patches are unsuccessful, or where a ventral defect is demonstrated, then a transforaminal approach can be used typically with CT guidance ²⁰. 

With CT guidance a needle (e.g.12-15 cm 22 G or 25 G spinal or Quincke pointneedle) is advanced along an anteromedial trajectory through the transverse foramen and into the ventral epidural space. Ideally, given that radiculomedullary arteries are located anterior to the nerve in the upper third of the foramen, the needle should pass through the inferior third. This may also limit the frequency of intravenous injection ²⁰. 

Once the epidural space is entered, extravascular and extrathecal location is confirmed with the injection of a small amount of contrast. 

Depending on how well the contrast spreads craniocaudally and/or left to right repeated injections on the contralateral side or at the level above/below may be of benefit ²⁰. 

Injection

After an epidural location is confirmed, the patient's blood is withdrawn (discarding the first 10-20 mL). This can be mixed with contrast to aid in visualising its spread.

The blood is then slowly injected checking frequently with the patient for symptoms and performing neurological observations on the feet. The volume injected depends on the location and size of the epidural space. It can be low (e.g. 2-3 mL when performing targeted multi-needle thoracic injection) or high (e.g.10-25 mL in non-targeted lumbar epidural injection in capacious canals). 

Complications

Complications include ^3,5:

• transient back pain: most common; pain may last up to 4 weeks ⁶
• radicular pain
• intrathecal haematoma
• spinal subdural haematoma
• cauda equina syndrome
• spinal epidural abscess

Outcomes

The success rate of non-targeted epidural blood patch is variable, reported between 50-95% for craniospinal hypotension and 90-99% for post lumbar puncture headache. In successful procedures, the patient's symptoms will objectively improve (some only temporarily), and the imaging features of craniospinal hypotension will reverse ^1,4,5. Sometimes multiple blood patches are required for a successful outcome.