77.: Uncovering the therapeutic mechanism of blood patching for treatment of spontaneous cerebrospinal fluid leaks

Abstract

The mechanism of action for lumbar blood patches affecting a therapeutic response in a proximal cerebrospinal fluid (CSF) leak is thought to be via a tamponade effect. However, our case study reveals that blood products reach and pool at the site of a proximal CSF leak in the cervical spine – therefore we hypothesise that the therapeutic response results from a combination of a tamponade effect and blood products forming a localised clot in the proximal cervical region. We present a 41-year-old woman with a 12 month history of headache from postural hypotension. The patient’s general practitioner ordered a CT scan of the brain and lumbar spine as part of a workup which revealed that the patient had a cervical spine CSF leak. Subsequent MRI confirmed the CSF leak and intracranial hypotension. A 25 ml epidural blood patch was performed in the lumbar region together with conservative measures including a period of strict bed rest for days with increased hydration and caffeine intake. The patient reported an immediate symptomatic improvement following blood patching with a reduction in headaches. Subsequent imaging revealed resolution of the intracranial hypotension. We followed up the patient with serial MRI scans. These revealed blood reaching and pooling around the site of the CSF leak in the cervical spine. The current case report demonstrates that a lumbar epidural injection of blood reaches and pools around a CSF leak as far proximally as the cervical region. This supports the “plug” theory as the mechanism for persistent symptom resolution. However, the mechanism of immediate symptomatic improvement may still involve a tamponade effect. This two stage process appears to be the best explanation for the therapeutic response obtained from epidural blood patching on the basis of the available clinical, imaging and experimental data.