A Most Unusual Subdural Block

COMPLICA TlONS: subduralCase reports of unusual epidurals, many presumed to be accidental subdural blocks, have been published frequently, including four confirmed cases in obstetric patients 1•4 since the first radiologically confirmed case in 1975.5 Although the features of subdural block may sometimes allow clinical differentiation from epidural or subarachnoid block,6 the presentation based on time course, extent of spread and associated complications appears quite variable.I • 5 .7 -9 This case report documents a very unusual obstetric epidural, atypical for either epidural or subdural block, in which subsequent injection of radiographic contrast via the epidural catheter demonstrated both subdural and epidural spread of solution.CASE REPORT A previously healthy 20-year-old, 152 cm primiparous woman was admitted at 30 weeks' gestation with severe pre-eclampsia.She was oliguric with severe generalised oedema, a recent ten kilogram weight gain and was suffering from acute bronchitis.Haematological and coagulation profiles were normal and epidural anaesthesia was chosen when she proceeded to elective caesarean section.Central venous and blood pressure monitoring were commenced prior to fluid preloading.The epidural space was located with a 16 g Tuohy needle at the L3-4 interspace using a midline loss of resistance to saline technique and left lateral positioning of the patient.The needle bevel was directed 'M.B.B.