Lumbar blood patching for proximal CSF leaks: where does the blood go?

SUMMARY Epidural blood patching (EBP) is an important therapeutic approach in managing spontaneous cerebrospinal fluid leaks. The mechanism of action of blood patching is likely to be twofold; fluid replacement having an immediate tamponade effect and the proximal flow of blood products having a ‘plug’ effect. The negative pressure gradient within the epidural space may be important to the rostral flow of injected blood and is possibly increased in intracranial hypotension. BACKGROUND Spontaneous cerebrospinal fluid (CSF) leaks are not uncommon and are associated with intracranial hypotension and postural headaches. Although a number of therapeutic approaches exist, first-line treatment generally consists of epidural blood patching (EBP) in the lumbar area, even in the setting of more proximal CSF leaks. We report a case of a cervical fluid leak being successfully managed with lumbar blood patching with follow-up imaging confirming that the blood ascended proximally within the epidural space. This case supports a twofold hypothesis: that the therapeutic response from lumbar blood patching initially results from a tamponade effect leading to immediate symptom relief and subsequently blood products ascending and forming a localised clot. The negative pressure gradient that exists within the epidural space may be essential to the rostral flow of injected blood products and this gradient is possibly augmented in the setting of intracranial hypotension.