Decreased paralysis and better motor coordination with microspinal versus PE10 intrathecal catheters in pain study rats

We compared the standard PE10 catheter to a smaller microspinal catheter for intrathecal (IT) catheterization in rats. The PE10 or microspinal catheter was implanted in the lumbar subarachnoid space through the atlantooccipital membrane in rats (21 each group). Surviving rats without paralysis were tested on a rota-rod treadmill for motor function on Postoperative Days (POD) 3-6. Different doses of IT butorphanol were injected to demonstrate the functionality of the catheters by measuring tail-flick antinociception. Methylene blue was injected IT immediately before the spinal necropsy in each rat to identify the catheter tip location. For PE10 and microspinal catheters, the immediate death rate after the catheter implantation was 4 of 21 and 3 of 21 (no significant difference); paralysis rate was 8 of 21 and 2 of 21 (P < 0.05), and motor coordination recovery on POD 6 was 67% and 91% (P < 0.01), respectively. Rats in both groups showed a dose-dependent response to IT butorphanol. Intrathecal methylene blue stained the lumbar spinal cord but not the surrounding tissue in both groups. Therefore, the microspinal catheter is better than the PE10 for IT catheterization in rats because it causes less paralysis and provides faster recovery of motor function.