Background and aim: Several authors have focused on a causal link between the onset of neurological complications after lumbar injections and the fact that epithelial cells may be drawn into the vertebral canal during these procedures. Complications may arise both early (cephalea, septic and aseptic meningitis) and late (epidermoid tumours). The authors aimed to evaluate whether skin fragments which are carried down by the needle during subarachnoid anesthesia may even be present in the epidural or subarachnoid space three days later and may therefore justify the onset of the above neurological syndromes.
Methods: Five adult cats under narcosis underwent subarachnoid anesthesia using disposable 22G Quincke type needles. Between 0.7 and 1 ml isobaric bupivacaine at 0.50% was injected. The presence of the motor block of the lower limbs was ascertained once the effects of general anesthesia wore off. On the third day, again under general anesthesia, cardio-respiratory arrest was provoked by intravenous injection. Samples of meninges were collected in the injection area. After fixation in a phosphate glutaraldehyde buffer, dehydration in acetone, dehydration by critical point and gold metalisation, the samples were examined using SEM.
Results: No epidermal cells were found on the surface of the meninges. On the other hand, a squamous epithelial cell was observed which drained inside a sectioned epidural vessel towards the systemic circulation.
Conclusions: This study confirms the possibility that, after subarachnoid anesthesia using 22G Quincke needles, skin fragments may enter the spinal canal. The permanence or otherwise of the epithelial fragments on the third day depends on the size of the fragment drawn down and the efficacy of the drainage system which removes isolated epithelial cells. This phenomenon may justify the self-limiting character of cephalea and meningisms which, even if not treated, regress in a few days, as well as the scarce development of epidermoid tumours.