Uneventful extradural analgesia after unrecognized dural perforation.

A case is reported of an uneventful continuous extradural block in spite of unrecognized dural perforation. Although the perforation was recognized later during the block, the dura was probably pierced during the insertion of the catheter and only later the terminal hole came to lie in the subarachnoid space. Consequently both extradural and subarachnoid spread of the injected local anaesthetic occurred, preventing an extensive subarachnoid block.