Comparison of the median and intermediate approaches to the ultrasound-guided sacral erector spinae plane block: a cadaveric and radiologic study.

BACKGROUND: Erector spinae plane block (ESPB) is a well-established method for managing postoperative and chronic pain. ESPB applications for the sacral area procedures are called sacral ESPBs (SESPBs). This cadaveric study aimed to determine the distribution of local anesthesia using the median and intermediate approaches to the SESPB. METHODS: Four cadavers were categorized into the median and intermediate approach groups. Ultrasound-guided SESPBs were performed using a mixture of radiopaque agents and dye. Following confirmation of the solution distribution through computed tomography (CT), the cadavers were dissected to observe the solution distribution. RESULTS: CT images of the median group demonstrated subcutaneous pooling of the radiopaque solution between the S1 and S5 horizontal planes. Radiopaque solution also passed from the sacral foramina to the anterior sacrum via the spinal nerves between S2 and S5. In the intermediate group, the solution distribution was observed along the bilateral erector spinae muscle between the L2 and S3 horizontal planes; no anterior transition was detected. Dissection in the median group revealed blue solution distribution in subcutaneous tissue between horizontal planes S1 and S5, but no distribution in superficial fascia or muscle. In the intermediate group, red solution was detected in the erector spinae muscle between the L2 and S3 intervertebral levels. CONCLUSIONS: Radiologic and anatomic findings revealed the presence of radiopaque dye in the superficial and erector spinae compartments in both the median and intermediate groups. However, anterior transition of the radiopaque dye was detected only in the median group.

Hippocampal cell loss after an anterior and posterior anastomotic vein occlusion model in rats.

Estimation of the cell number after cortical venous ischemia/infarction induced by anterior and posterior anastomotic veins occlusion in a rat model is very important. Twenty male Sprague-Dawley rats were used in this experiment. Small burr-holes were made over the anterior (the crossing point of the line drawn from the posterior border of the orbital rim and the line drawn along the para-midline to the superior sagittal suture) and posterior (just inferior point of the posterior ending of the zygomatic arch) anastomotic veins. Bipolar coagulation technique and micro-scissor were used to sacrifice the venous vessels after final inspection and description. Specimens were evaluated by histopathological and unbiased stereological methods for microscopic evaluation and volumetric analysis, respectively. Significant cell loss was seen in the pyramidal and granule cells of the cornu ammonis and dentate gyrus of the hippocampus after venous ischemia. Cell loss was also pronounced when seen in the histological examination. The present results suggest that the sacrifice of anterior and posterior anastomotic veins can be used as an experimental rat model in the evaluation of pyramidal and granule cell loss in the hippocampus that often assesses the neural damage inflicted by this intervention.