Introduction:
The injection of autologous blood into the epidural space is known as an epidural blood patch (EBP). Since 1955, this procedure has been practiced to treat headache associated with low intracranial pressure. This procedure is mainly intended to heal the dural leak by sealing or stopping the CSF leak. Initially, the EBP was done with 2-3 ml of blood by Gormley, then increased to 6-10 ml by Crawford in 1980 and showed 70% success. Now, it has evolved to 20 ml of blood with 96% success. This article briefs on the current indications, procedural considerations and modifications of EBP.
Procedural Considerations:
Commonly, EBP was indicated in the following conditions:
Low intracranial pressure with headache as per the International Classification of Headache Disorders – 3 (ICHD), like PDPH (post-dural puncture headache), CSF fistula, SIH (spontaneous intracranial hypotension), chronic daily headache with postural component, and CSF leak after spinal or thoracic surgery.
EBP should be performed after written informed consent and with antibiotic coverage and strict aseptic precautions for both blood collection and epidural puncture. Fluoroscopically guided interlaminar or transforaminal approach is better than a blind approach because with fluoroscopy, contrast epidurogram will guide the injection site and the rough area of blood spread. In case of PDPH, the insertion site of the epidural needle should be at one level lower than the dural puncture site. But in the case of SIH, the insertion site is preferred at the mid-thoracic or cervical level because, in the case of SIH, the commonest site of CSF leak would be in and around the cervical spine.
The two prominent theories that exist regarding EBP are the mass effect theory and the theory of epidural plug formation. The first one explains the mass effect produced in the epidural space that reduces the CSF leak. The next one is about the repair of the dural tear, thereby reducing the CSF leak. Usually, the headache will be relieved within 3 hours (mass effect), whereas other symptoms will take 48 to 72 hours. If the symptoms have not been relieved with the first attempt, then the second EBP can be repeated after 5 days with further neurologist opinion. Post-procedure, the patient should be in the supine position for 3-4 hours; this is to promote clot formation. Another precaution to be followed is avoiding strenuous exercise, Valsalva activity and travel. In the first attempt, the success rate of EBP is 95% to 97% if performed correctly. But for the second attempt, it will decline to 70%, even if it is performed correctly.
The complications associated with EBP are infections, blood clot-induced sudden weakness, meningism due to irritation of dura, seizure, transient bradycardia and cauda equina syndrome. Considering all these, EBP should be attempted only if the conservative and pharmacological methods have failed.
Conclusion:
To conclude, therapeutic EBP is particularly indicated in PDPH and SIH only after 7-10 days of failed conservative measures. EBP can be safely performed under fluoroscopic guidance with an epidurogram. The severity of the symptoms determines the timing of EBP, and the cranial nerve involvement, especially the abducens nerve (CN VI) warrants immediate initiation of EBP.
Dr. Karthickraja Velayutham
Senior Consultant Anaesthesiologist,
Kauvery Hospital, Chennai
