Appearance of the Tracer Substance in the Spinal Cord following injection into or around the Coeliac Plexus

Chon, Jin Young; Choi, Joo Young

Abstract

The present study was undertaken in an attempt to explore the spinal cord after injection of a tracer substanee into the coe1iac plexus. We studied two groups of rabbits weighing 2.0 to 2.3 kg ; a normal control group and the experimental group. The animals were anesthetized with 20 % urethane 7 ml/kg body weight intraperitoneally. To make an injectable mixture of the tracer substance, 0.5 gm of ferric oxide (Iron sesquioxide) was mixed with 2 ml of lactated Ringer's solution just prior to injection. In normal control group (N=3), animals were killed after anesthetization by shedding blood and the segment of vertebrae from the 6th thoracic to 11th thoracic were removed and fixed in 10% formalin solution. The experimental group was subdivided into a subgroup of perineurial injection of the tracer mixture to the bilateral coeliac ganglia (the perineurial injection subgroup, N=5), a subgroup of intraneural injection of tracer mixture to the bilateral coeliac ganglia (the coeliac ganglion subgroup, N=5) and a subgroup of intraneural injection of the tracer mixture to the bilateral superior mesenteric ganglia (the superior mesenteric ganglion subgroup, N=3). In the perineurial injection subgroup, the bilateral coeliac ganglia were exposed under surgical microscope and 1 ml of the tracer mixture was injected bilaterally exterior to the perineurial connective tissue of coeliac ganglion. After the injection, the abdominal wall was closed and animals were then allowed to rest in the lateral position for 2 hours. In the coeliac ganglion subgroup and the superior mesenteric ganglion subgroup 0.6 to 0.7 ml of the tracer mixture was injected bilateraUy into the coeliac ganglia or the superior mesenteric ganglia. After the injection, the aMominal wall of the animals were closed and then allowed to rest in the lateral position for 90 minutes. At the end of experiment, animals of the experimental group were killed by shedding blood and the segment of vertebrae from the 6th thoracic to 11th thoracic were removed and fixed in 10% formalin solution. Following decalcification in 50% formic acid, histological study was performed with hematoxilin-eosin(H-E) stain or iron stain in transverse sections and sagittal plane of specimen which was obtained in one animal of the coeliac ganglion group. The results were as follows ; 1. In the perineurial injection subgroup, moderate density of the tracer substance was diffused into the dura mater. There was minimally infiltrated tracer in the area of lateral side of the formatio reticularis and the perivascular space of the white matter and pia mater. 2. In the coelic ganglion subgroup many tracer were diffused into the perineurial epithelial space of unmyelinated fibers and around the Schwann's sheath of fibers in the ventral and dorsal roots. The white matter was infiltrated uniformly with the tracer substance. there was evidence of diffusion of the tracer substance through the glia limitans of the white matter in the transversely or sagittally sectioned slides. 3. The superior mesenteric ganglion was tightly encased with the connective tissue capsule, thus we experienced moderate resistance to injection of the tracer mixture. There was most extensive diffusion of the tracer substance in the ventral and dorsal roots, dorsal horns of the gray matter, the area of the lateral side of the formatio reticularis and the remaining whole area of the white matter. And the tracer substance was infiltrated around the peripherally situated cells of gray matter. Our observation demonstrate that the tightly encased ganglion like the superior mesenteric ganglion is the candidate for paralysis when a neurolytic agent was injected intraneura1ly. In discussion we indicated the existance of small ganglion on the wall of upper abdominal aorta which is prone to produce paraplegia of the distal extremities in case of neurolytic coeliac plexus block.