Epidural blood patch
From Wikipedia, the free encyclopedia
| Epidural blood patch | |
|---|---|
 Diagram of an epidural blood patch | |
| ICD-10-PCS | G97.1 |
| MeSH | D017217 |
An epidural blood patch (EBP) is a surgical procedure that uses autologous blood, meaning the patient's own blood, in order to close one or many holes in the dura mater of the spinal cord, which occurred as a complication of a lumbar puncture or epidural placement.[1][2] The punctured dura causes cerebrospinal fluid leak (CSF leak).[1] The procedure can be used to relieve orthostatic headaches, most commonly post dural puncture headache (PDPH).
This procedure carries the typical risks of any epidural procedure. EBP are usually administered near the site of the cerebrospinal fluid leak (CSF leak), but in some cases the upper part of the spine is targeted.[3] An epidural needle is inserted into the epidural space like a traditional epidural procedure. The blood modulates the pressure of the CSF and forms a clot, sealing the leak.[4][5][6] EBPs were first described by American anesthesiologist Turan Ozdil and surgeon James B Gormley around 1960.[7]
EBPs are an invasive procedure but are safe and effective—further intervention is sometimes necessary, and repeat patches can be administered until symptoms resolve.[6][4][8] It is considered the gold standard treatment for PDPH. Common side effects include back pain and headache. Rebound intracranial hypertension in people with spontaneous intracranial hypotension (SIH) is common, and people with SIH may have less success with EBPs. While the procedure uses blood, it does not carry a significant infectious risk, even in immunocompromised people.[9] The procedure is not entirely benign—seven cases of arachnoiditis have been reported as a result of administration.[10]
EBPs are administered for treatment-related or spontaneous orthostatic headaches.[11] The procedure is most often used to relieve PDPH following an epidural injection or lumbar puncture.
Post dural puncture headache (PDPH) is a side of effect of spinal anesthesia, where the clinician accidentally punctures the dura with the spinal needle and causes leakage of CSF. Factors such as pregnancy, having a low body mass index, being a female and young, increase the risk of dural puncture.[12][7] The most common population at risk are pregnant patients, as they are usually young females, who commonly undergo epidural placements for pain control. It is estimated that the likelihood of a dural puncture occurring as a result of epidural catheter placement is 1.5%, with PDPH occurring in as much as 50% of these cases.[6][3]
Dural punctures usually present with a headache or backache within 3 days of the procedure.[13] The headache causes pain over the forehead and the back of the head. A distinguishing feature between PDPH and other types of headaches is the exacerbation of the headache with standing, and is non-throbbing like the common tension headaches.[13] As a result, many clinicians advise patients to lay flat and hydrate well to minimize the risk, but the efficacy of this practice has been questioned.[3]
Most PDPHs are self-limiting, so epidural blood patches are only used for people with moderate to severe cases who do not respond to conservative treatment.[2][9] In these patients, the headache is usually so severe that it affects the patient's ability to carry out normal daily tasks, and in cases of postpartum women, the concern is they are unable to care for themselves or their newborns.[13]
EBP is also used to treat spontaneous intracranial hypotension (SIH).[5][9] EBP has been used to treat pseudomeningoceles and leaks around intrathecal pumps.[14] For SIH, the same administration technique is used but at a different location with a different amount of blood injected.[15]
Technique
Anatomy
An epidural is injected into the epidural space, inside the bony spinal canal but just outside the dura. In contact with the inner surface of the dura is another membrane called the arachnoid mater, which contains the cerebrospinal fluid. In adults, the spinal cord terminates around the level of the disc between L1 and L2, while in neonates it extends to L3 but can reach as low as L4.[16] Below the spinal cord there is a bundle of nerves known as the cauda equina or "horse's tail". Hence, lumbar epidural injections carry a low risk of injuring the spinal cord. Insertion of an epidural needle involves threading a needle between the bones, through the ligaments and into the epidural space without puncturing the layer immediately below containing CSF under pressure.[16] For administration of an EBP due to PDPH, the level of prior epidural puncture is targeted;[15] blood injected for the most part spreads cranially.[4] For SIH with unidentified leakage spots, L2 and L3 are targeted initially.[15]
Insertion
For EBPs, autologous blood is drawn from a peripheral vein;[2][17] the procedure uses a typical epidural needle.[2] 20 mL of blood is recommended for EBPs, though injection should stop if not tolerated by the patient.[9] This amount of blood is also recommended for people in obstetrics.[18] Targeted EBP is performed under real-time fluoroscopy if the location of the CSF leak is known.[9] This fluoroscopic approach is standard,[15] but with cases of SIH two-site blind injection has similar outcomes. No randomized clinical trials have been conducted for this due to the rarity of SIH.[1] CT scanning can also be used.[9] Blood from EBPs is spread throughout several segments within the epidural space, so it does not need to be injected at the same level as the puncture.[17] For treatment of SIH, medication with acetazolamide before an EBP and administration in the Trendelenburg position is effective.[19]
Mechanism
When an EBP is administered a mass effect occurs which compresses the subarachnoid space, thereby increasing and modulating the pressure of the CSF, which translates intracranially. Blood maintains a pressures surge for a longer time than crystalloid fluids. Simultaneously, an "epidural plug" is formed as a result of clot formation; the clot adheres to the thecal sac, potentially becoming a permanent plug.[9][15][8] After about half a day the mass effect stops, and a mature clot is left.[8]
Contraindications
Epidural blood patches are contraindicated in people with bleeding disorders, infection at the puncture site, fever, and bloodstream infections or sepsis.[9] Some clinicians recommend obtaining blood cultures before administration of EBP to ensure the absence of infections.[8] EBP may be contraindicated in people with a spinal deformity, HIV/AIDS, and leukemia. Epidurals are recommended for perioperative COVID-19 patients over general anesthesia—EBPs have an extremely low risk of transferring an infection to the central nervous system even with an ongoing infection but are a last resort after conservative treatments and nerve blocks.[9] Though little large-scale clinical studies have been conducted, and no adverse effects have been reported thus far, EBP are a relative contraindication in patients with malignancies.[17]
Risks/Complications
Common side effects are headache, back pain, neck pain, and mild fever. Back pain is reported in approximately 80% of people, which might be a result of increased pressure. Radicular pain may also occur.[9] Rebound intracranial hypotension is very common in people with SIH after an EBP, and can be treated with acetazolamide, topiramate, or in severe cases therapeutic lumbar puncture; most cases are not severe. Rare side effects include subdural or spinal bleeding, infection, and seizure,[9] though EBPs do not carry a significant infectious risk even in immunocompromised people.[14] Neurological symptoms occasionally develop as a result of administration.[4] Seven cases of arachnoiditis have been documented.[10] As a result of the procedure, additional dural puncture can occur, which may increase the chance of inadvertently injecting blood intrathecally.[9]