HEADACHE AFTER ATTEMPTED EPIDURAL BLOCK - THE ROLE OF INTRATHECAL AIR

Background: Postmeningeal puncture headache (PMPH) is typically attrib uted to che loss of cerebrospinal fluid (CSF). However, when it occurs after an attempted epidural puncture, it may be due to either CSF los s or, potentially, to the subarachnoid infection of air used as a part of ''loss-of-resistance'' testing. This study was performed to examin e the relation between intrathecal air and PMPH. Methods: Using a loss -of-resistance test with an air-filled (n = 1,812; air group) or salin e-filled (n = 1,918; saline group) syringe, epidural block was perform ed in patients with acute or chronic pain. The dura was judged to be p erforated nest only where backflow of CSF was recognized in the needle but also when signs and symptoms solely attributable to meningeal per foration were seen, such as high spinal blockade or severe motor block ade. The incidence, onset time, and duration of PMBH in the air and sa line groups were compared. In all patients with signs of meningeal per foration, brain computed tomography was examined. Results: The inciden ce of PMPH in the air group (32 cases) was significantly higher than t hat in the saline group (5 cases), although the occurrences of meninge al perforation between the air (48 cases) and saline (51 cases) groups did not differ significantly. Intrathecal air bubbles were detected o n brain computed tomography in both the deep supraspinal structures su ch as the ventricles, Silvian fissures and cisterns, and the superfici al subarachnoid space in 30 of 32 patients with PMPH in the air group, whereas no intrathecal air bubbles were seen in the saline group. PMP H was significantly more rapid In onset and shorter he duration in the air group than that in the saline group. Conclusions: The use of air for loss-of-resistance testing during epidural block was associated wi th a higher incidence of PMPH, which might be attributable to subarach noid air injection and CSF leakage.