The lumbar sympathetic trunk: its visibility and distance to two anatomical landmarks.

OBJECTIVE: The lumbar sympathetic trunk's (LST) distance to two anatomical landmarks, the costal process and medial margin of the psoas muscle, was assessed due to its use as landmarks for lumbar sympathetic blocks: the costal process for fluoroscopic guided techniques and the psoas major for CT- and MRI-guided techniques. Based on the measurements, we evaluate the trunk's visibility in MR and CT images for accurate positioning of the needle. METHODS: A total of 54 cadavers embalmed with Thiel's method were investigated. The LST's distances to the psoas major's medial margin and to the base of the lumbar vertebrae's costal process were measured on the levels L2/3, L3/4 and L4/5. The measurements were compared to MR and CT images of 20 anonymous patients to identify the LST. RESULTS: LST's mean distance to the psoas major was 0.3 mm at L2/3, 3.1 mm at L3/4 and 4.6 mm at L4/5. The mean distance to the costal process was 31 mm at L2/3, 34 mm at L3/4 and 32.6 mm at L4/5. In both MR and CT imaging, a structure could be determined as the LST correlating to the measurements with decreasing possible identification from cephalad to caudad levels. CONCLUSIONS: The costal process is a usable landmark for fluoroscopic guidance and the psoas major for CT- and MRI-guided techniques. The LST is clearly visible in MR and CT images, which gives both techniques a decisive advantage over fluoroscopy concerning the block of the LST due to a visible target.

Reliability of Tuffier's line evaluated on cadaver specimens.

The aim was to evaluate the reliability of Tuffier's line usually used as sole method to identify lumbar spinous process for a correct needle placement. Fifty-eight cadaver specimens were placed in a lateral position and a flexion in the lumbar spine performed to achieve a neutralization of the lumbar lordosis. The iliac crests were palpated and the lumbar spinous process marked on the intercristal line with a pin; all specimens were dissected and the marked spinous process documented. The center of the L4 spinous process was hit in 24 male (41.38%) and 10 female (17.24%) specimens. In only two female specimens (3.45%), the upper vertebra was reached; a pin placed in L3 was not found in male cadavers. The inferior edge of the L4 spinous process was hit in male 4 times (6.90%) and in female cadavers 12 times (20.69%). In the fifth lumbar spinous process, pins were placed five times in female cadavers (8.62%) and in only one male cadaveric specimen (3.72%). In conclusion, the accuracy of the focused lumbar spinous process depends on the right bedding and the orientation of the given landmarks, so Tuffier's line stays the most important tool for anesthetists if palpation is performed very precisely.

Superior vestibular neurectomy: a novel transmeatal approach for a denervation of the superior and lateral semicircular canals.

OBJECTIVE: To assess morphologically a transmeatal approach to the lateral and superior ampullary nerves performable under local anesthesia and simultaneously with the existing approach to the singular nerve developed by Gacek during the same operation. MATERIALS AND METHODS: Eighty halves of human heads preserved with the Thiel method were operated on by an otologist. Two surgical approaches were tested on each specimen, 1 superior and 1 inferior to the tympanic segment of the facial nerve. The 80 specimens were divided into 2 groups. In the first group, the osseous canal of the nerves of the lateral and superior semicircular canal were previously probed and next operated. In the second group, the osseous canal of the nerves were operated prior assessment by dissection. Afterward, all 80 halves underwent computed tomographic investigation to measure the distance between the entrance point of the drill in the medial wall of the tympanic cavity and the osseous canal the ampullary nerves. RESULTS: Inferior approach to the canal of the nerves could not be done without wide opening of the vestibulum in all 80 specimens. In the superior approach, the nerve could be reached directly in 5 cases, and only via the osseous ampulla of the lateral semicircular canal in 28 cases in the first group. In 7 cases, the nerves could not be reached without damage to the membranous labyrinth. In the second group, the nerve could be reached directly in 2 cases, via the osseous ampulla in 36 cases, and was unreachable in 2 cases. Significantly, distances longer than 3 mm between the surgical access and the nerve were found on the inaccessible cases. CONCLUSION: A transmeatal approach is possible superiorly but not inferiorly to the facial nerve, although it is necessary to open the osseous ampulla but not the membranous labyrinth in most cases.