Epidural blood patch in a patient with multiple sclerosis: is it safe?

Multiple sclerosis (MS) is a chronic inflammatory and degenerative disease of the central nervous system resulting in demyelination and axonal injury. Epidural blood patch (EBP) to treat postdural puncture headache (PDPH) in an MS patient may be of concern because of the potential for this to interfere with axonal conduction. Even with normal axons, pressure can interfere with impulse conduction, and it is unknown whether affected axons of the MS patient are particularly vulnerable to the increase in epidural pressure that occurs as a consequence of the EBP. We describe our experience with EBP in an MS patient. While peridural pressure changes were not measured, we attempted to quantify any pressure-induced interference with axonal conduction by measuring changes in somatosensory evoked responses.

A 50-yr-old female MS patient required an EBP for a PDPH after a diagnostic lumbar puncture. The first EBP (20 mL autologous blood, L3-4 interspace) was followed by a transient improvement in PDPH and then a worsening with increased lower-extremity weakness. A second EBP was performed (12 mL autologous blood, L3-L4 interspace) with concomitant evoked potential recordings (stimulating electrodes over the left posterior tibial nerve and recording electrodes at CZ-FZ coordinates). Postdural puncture headache symptoms were permanently relieved, and the effects of the EBP on evoked P40 latency responses (39.7 msec and 44.3 msec pre- and post-EBP, respectively) were considered to be physiologically insignificant.

A report of EBP to treat PDPH in an MS patient is presented. We postulate that this type of patient may be at risk for impaired conduction of impulses in affected axons due to the increase in pressure produced by epidural injection of blood. Literature review indicates that pressure increases may be reduced by injecting the blood slowly. When EBP is considered in patients with axon conduction deficits, consideration should be given to concomitant monitoring of somatosensory evoked responses to help quantify interference with axonal conduction as a consequence of injection of blood into the epidural space.